Proceedings of the Seventeenth LAMPF Users Group Meeting Los Alamos National Laboratory Los Alamos, New Mexico November 7-8,1983

H0T1C6

LA—100C0-C

ability. DS84 01413 4

Compiled by James N. Bradbury

Editing and Production Kit Ruminer Beverly Talley

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Refer- ence herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Los Alamos National Laboratory Los Alamos, New Mexico 87545 ABSTRACT

The Seventeenth Annual LAMPF Users Group Meeting was held November 7-8, 1983, at the Clinton P. Anderson Meson Physics Facility. The program included a number of invited talks on various aspects of nuclear and particle physics as well as status reports on LAMPF, A panel discussion on the LAMPF II concept provided an exchange of views among an advisory group, Users, and LAMPF staff. The LAMPF working groups met and discussed plans for each of the secondary beam lines.

IV LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory CONTENTS

PROGRAM 2

STATUS OF LAMPF, Louis Rosen 4

OPERATIONS REPORT, Andrew Browman 15

STATUS REPORT ON THE PULSED SPALLATION NEUTRON SOURCE AT THE LOS ALAMOS NATIONAL LABORATORY. Charles D. Bowman 20

STATUS OF LAMPF II. H.A. Thiessen 28

PANEL DISCUSSION OF LAMPF II PROPOSAL 37

NEW APROACH TO POLARIZED PROTON SCATTERING BASED ON DIRAC DYNAMICS. Stephen J. Wallace 45

MUON-NEUTRINO PHYSICS BEFORE THE PSR, G. J. Stephenson, Jr 62

ENERGY AND ANGULAR DEPENDENCE OF THE TENSOR POLARIZATION

r20 IN nd ELASTIC SCATTERING. W. Griiebler 66

TENSOR POLARIZATION IN PION-DEUTERON ELASTIC SCATTERING, R. J. Holt 76

NUCLEON-NUCLEON PHASE-SHIFT ANALYSIS UP TO 800 MeV. C. Lechanoine-LeLuc 86

A STUDY OF NEUTRINO-ELECTRON ELASTIC SCATTERING. H. H. Chen .... 98

SIMPLE FEATURES OF (pn~) REACTIONS NEAR THRESHOLD. Steven Vigdor (not available) 107

WORKING GROUP MEETINGS 108 Energetic Pion Channel and Spectrometer (EPICS) 108 Solid-State Physics and Materials Science •. 108 Nucleon Physics Laboratory (NPL)/Polarized Facilities 110 Muon-Spin Rotation (uSR) Ill Low-Energy Pion (LEP) Channel Ill Nuclear Chemistry 112 High-Resolution Spectrometer (HRS) 113 High-Energy Pion (P3) Channel 114 Stopped Muon Channel (SMC) 115 Computer Facilities 116 Neutrino Facilities 117

November 1983 LAMPF USERS GROUP PROCEEDINGS V Los Alamos National Laboratory PARTICIPANTS 126

LAMPF USERS GROUP NEWS 134 1984 Board of Directors of the LAMPF Users Group, Inc 134 1984 Working Group Chairmen 134 Notice of Date for Next Users Grou}, Inc., Meeting 135 LAMPF Program Advisory Comm.itee (PAC) 135 1984 Technical Advisory Panel (TAP) of the LAMPF Users Group. Inc 136 Science Policy Advisory Committee (SPAC) 136

LAMPF USERS GROUP, INC.. (LUGI) MINUTES 137 Board of Directors 137 Technical Advisory Panel 138

SUMMARIES OF RECENT LAMPF PROPOSALS 141

VI LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory PROCEEDINGS

OF THE

SEVENTEENTH LAMPF USERS GROUP MEETING

Los Alamos National Laboratory November 7-8, 1983

November 1983 LAMPF USERS GROUP PROCEEDINGS 1 Los Alamos National Laboratory PROGRAM

SEVENTEENTH ANNUAL LAMPF USERS GROUP MEETING

Los Alamos National Laboratory November 7-8. 1983

Chairman: George Igo, University of California at Los Angeles Chairman-Elect: Charles Glashausser, Rutgers College

Monday, November 7 LAMPF Auditorium, Laboratory-Office Building (MPF-I, TA-53)

MORNING SESSION

George Igo, Presiding

8:00 - 9:00 a.m. Registration 9:00 - 9:15 Welcome — Warren F. Miller, Associate Director of the Los Alamos National Laboratory 9:15 - 10:00 LAMPF Status Report — Louis Rosen, Director of LAMPF 10:00 - 10:30 LAMPF Operations Report — Andrew A. Browman (Los Alamos) 10:30 -11:00 COFFEE BREAK 11:00 - 11:15 Annual Users Group Report — George Igo, Chairman of Board of Directors General Business Session Election Results Winner of Louis Rosen Prize Treasurer's Report 11:15 - 12:00 Proton Storage Ring Research — Charles Bowman (Los Alamos) 12:00 - 1:30 p.m. LUNCH — Buses to the Laboratory Support Complex Cafeteria

1:30 p.m. LAMPF Auditorium, Laboratory-Office Building (MPF-1, TA-53)

AFTERNOON SESSION

Charles Glashausser, Presiding

1:30 - 2:15 p.m. Steven J. Wallace (University of Maryland) — "New Approach to Polarized-Proton Scattering Based on Dirac Dynamics" 2:15 - 2:45 Henry A. Thiessen (Los Alamos) — "Progress Report—LAMPFII" 2:45 - 3:15 Gerard Stephenson (Los Alamos) — "Muon Neutrino Physics Before the PSR" 3:15 - 3:30 COFFEE BREAK 3:30 - 5:00 Round table discussion on the present LAMPF II concept in the context of nuclear and particle physics needs Jie 1990s — SPAC Committee and Board of Directors Moderator — Erich W. Vogt (TRIUMF) 7:00 p.m. BANQUET at RANCHO ENCANTADO (Tickets to this event must be purchased in advance.)

2 LAMPF USERS GROUP PROCEEDINGS November 7983 Los Alamos National Laboratory Tuesday, November S LAMPF Auditorium, Laboratory-Office Building (MPF-I, TA-53)

MORNING SESSION 8:30 - 9:00 i.m. Wilii Griiebler (ETH), "Energy and Angular Dependence of the Tensor Polarization T20 in 7td Elastic Scattering" 9:00 - 9:30 Roy Holt (Argonne) — "Tensor Polarization in Pion-Deuteron Elastic Scattering" 9:30 - 10:15 Steven Vigdor (Indiana University) — "Simple Features of(pn~) Reactions Near Threshold" 10:15 - 10:45 COFFEE BREAK 10:45 -11:30 Catherine Lechanoine-Leluc (University of Geneve) — "pp and np Phase Shifts up to SOOMeV" 11:30-12:15 p.m. Herbert Chen (University of California, Irvine) — "Status of Exp, 225, A Study of Neutrino- Electron Elastic Scattering" 12:15 - 1:30 LUNCH — Buses to the Laboratory Support Complex Cafeteria

1:30 p.m. LAMPF Auditorium, Laboratory-Office Building (MPF-I, TA-53)

AFTERNOON SESSION 1:30- 2:15 p.m. A. Trivelpiece, DOE

2:15-3:30 p.m. WORKING GROUP MEETINGS

EPICS (Energetic Pion Channel Susan Seestrom-Morris (Los Alamos), Chairman LAMPF, Room A-234 and Spectrometers LEP (Low-Energy Pion Channel) Barry Preedom (University of South Carolina), Chairman LAMPF, Room D-105 Neutrino Facilities Herbert Chen (University of California. Irvine), Chairman LAMPF Auditorium NPL (Nucleon Physics Laboratory) Olin van Dyck (Los Alamos), Chairman Polarized Facilities Michael McNaughton (Los Alamos), Chairman LAMPF. Room A-114 Computer Facilities Michael McNaughton (Los Alamos), Chairman SMC (Stopped Muon Channel) Gary Hogan (Temple University), Chairman (Appointed) LAMPF, Room A-142

3:30- 5:00 p.m.

HRS (High-Resolution Kevin Jones (UCLA), Chairman LAMPF, Room A-234 Spectrometer) uSR (Muon Spin Rotation) Carolus Boekema (Texas Tech), Chairman LAMPF, Room A-228 Nuclear Chemistry Jan Wouters (Los Alamos), Chairman LAMPF, Room D-105 P3 (High-Energy Pion Channel) William Briscoe (George Washington University), Chairman LAMPF, Room A-218 Solid-State Physics and Walt Sommer (Los Alamos), Chairman LAMPF. MP-14 Materials Science Conference Room

4;30-5:30 p.m.

Computer Facilities Michael McNaughton(Los Alamos), Chairman LAMPF Auditorium (5-year plan)

November 1983 LAMPF USERS GROUP PROCEEDINGS 3 Los Alamos National Laboratory STATUS OF LAMPF

Louis Rosen, Director Los Alamos Meson Physics Facility Los Alamos National Laboratory

Introduction

This, the 17th meeting of the LAMPF Users Group, Inc., (LUGI) may represent a turning point in your association with LAMPF. The winds of change are very strong. The federal laboratories have been studied and some of them have been found wanting. The most severe criticism is that many of them have outgrown their original mission; others are perceived as having diversified to such an extent as to compromise their major goals. More than one laboratory will be redirected and reorganized, hopefully for the better. The Los Alamos National Laboratory is, in my opinion, among the most fortunate because its primary mission and primary goal are clear and vital. LAMPF is triply fortunate. First, it strongly supports the national quest for excellence in science that Pete Miller alluded to awhile ago. Such excellence is absolutely crucial if Los Alamos is to fulfill its national security mission. Second. LAMPF provides unique technical resources in direct support of the Los Alamos primary mission—the Weapons Neutron Research (WNR) facility, the Proton Storage Ring (PSR). and isotope production. And third and probably most important, LAMPF is an important factor in providing the knowledge base and people base for the nuclear science Louis Rosen enterprise in this country and for the derivative technologies that are so essential to industrial, defense, and medical applications. From a recent in-depth review of nuclear science in the constant between science and the way people live is a United Kingdom (and I urge all of you to have a look at very strong one. this review). I show you an interesting compilation The next 5 years will be golden ones for LAMPF in (Fig. 1). This is an amazing correlation between gross terms of the quality and quantity of research to which we national product per capita and the number of nuclear can look forward. But unless definitive and major steps physicists per capita. In all fairness I should tell you that are now initiated, the ability of LAMPF to continue to if you substitute scientists for nuclear physicists, you fulfill its mission during the 1990s will be in serious would probably get the same correlation. But the thing jeopardy, and it is this point that is my main focus this that is important, and the thing that our policy makers morning. and lawmakers should observe, is that the coupling

4 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory I5r-

Swtzerland

, , , , I , r , I

Nuclear Physicists per 10 People

Fig. 1. Correlation between gross national product per capita and the number of nuclear physicists per capita for European countries and the United States.

Immediate Past act of Congress was twofold: (1) Congress mandated that $3 million of defense-program moneys be allocated Fiscal year 1983 was a good year even though we to LAMPF operations, and (2) they also specified in experienced our most severe technical challenge to the their continuing resolution that additional funds be physical maintenance of the facility—that is, we appear allocated for all of nuclear science, some of which were to have surmounted the most difficult remote-mainten- earmarked for LAMPF. The act of Don Kerr comprised ance tasks that one could reasonably foresee. We a decision to decrease, for 1 year, the amount of moneys therefore are well on the way toward developing remote- that the Laboratory is obliged to put aside for so-called maintenance capabilities that can be used to cope, in a fringe benefits. reasonable time, with any currently forseeable eventu- These developments, taken together, permitted us not ality. only to operate the planned number of hours (in fact, we Fiscal year 1983 was a vintage year in other respects. exceeded the 3100h that we had promised—not by We hosted 402 experimenters from about 80 institutions much, but by about 50), but also to alleviate budgetary in this country and foreign lands, and a total of 95 constraints on a number of LAMPF improvements and experiments received beam time. experiments. I have in mind One reason for our successes was that, even though • the neutrino experiment east of the beam stop; there was no appropriations bill, our budgetary situation • the development, in conjunction with P Division, of was viable. As a result of innovative budgetary measures Line E for another neutrino experiment; by the DOE, but also as a result of an act of God, an act • progress on the Low-Energy Pion (LEP) channel of Congress, and an act of Don Kerr, we had adequate spectrometer and progress on the time-of-flight funds to support our staff and LAMPF Users in a cost- spectrometer; effective way. • the Crystal Box initiative; and The act of God had to do with heavy snows the past • the large multinational collaboration on the High- winter that made available relatively inexpensive Resolution Spectrometer (HRS). hydroelectric power in greater quantity than normal. The

November 7983 LAMPF USERS GROUP PROCEEDINGS 5 Los Alamos National Laboratory Unfortunately, even a comparatively good budgetary To have such a plan, we must ask whether the physics year cannot exhaust the large backlog of maintenance remaining to be done with polarized protons at our and improvements that has accumulated over the years, energies justifies the expenditure that would have to be and new ones are continually emerging. I mention two of made. My personal perception is that indeed it does; in these, because to me they loom as of the most immediate fact, that was also the perception of the Vogt Panel, importance. which, in one of its rare criticisms of our procedures over 1. It has now been almost 10 years since we laid the past 20 years, wondered why we hadn't done this out a comprehensive plan for the development of a sooner. I think I know why and I think they know why, computer-based data-acquisition and control system at but it was good that they wondered. It is, however, for LAMPF. You Users were heavily involved in the devel- you to say, because you are the ones who will propose opment of these plans, and it is clear in retrospect that and implement the experiments. our final decisions were both wise and realistic. We have I therefore have asked Mike McNaughton to enjoyed an adequate data-acquisition and control sys- coordinate the studies necessary to determine on the one tem, but the system that controls the accelerator and hand whether a $2- to $3-million expenditure for a primary beam transport now must be updated out of dire polarized ion source at LAMPF is scientifically necessity. justifiable, and on the other, whether we see a commit- What happened was that the company that built the ment from appropriate people—from among you—to computer no longer exists. It was the only computer, at help realize that capability and then make proper use of that time, that could serve these functions (I remind you it. In the meantime, Don Hagerman, Andy Browman, that LAMPF was the first major facility designed to be Olin van Dyck, and others will determine which ion completely computer controlled). Anyway, that com- source is the most likely to succeed and also is most pany went out of business a few years ago, parts no affordable in money and time. longer are being made for their computer, and we simply I am sorry to report to you that the pion therapy have no choice but to move to another control computer. program has not been reinstated, although our ex- And we are doing that. perience is being utilized at SIN and TRIUMF. The system that is dedicated to the experimental NOTE: Now I will tell you something that happened programs is now also becoming obsolete, and mainten- just a few days ago that didn't have time to get into this ance costs are getting very high, almost at the talk. A proposal (with principal investigator, Mudundi $1 million/year level right now. At the same time, more Raju) to do radiobiology in support of the SIN and powerful and more cost-effective hardware and software TRIUMF therapy programs was given very high marks systems are foreseeable. It is therefore time to plan for by a National Cancer Institute (NCI) high-level committee. I am sure, 95% sure, that this proposal will be the next 10 years, and once again it is crucial that you be funded and that we will therefore resume our activities in heavily involved in the planning and decision-making this field. My hope and expectation, assuming the SIN- process. TRIUMF experiments proceed as well as they are now I therefore asked, some months ago, that Earl Hoff- proceeding, is that in about 2 years NCI will insist that man convene whatever is necessary by way of study we resume treating patients at this facility. Those of you who come back here 2 years from now can judge panels and workshops to address the problem; Martha whether or not I am a reliable prophet. Hoehn is devoting a lot of time to this. I urge all of you, and especially the Board of Directors and the Technical However, I do want to emphasize and reemphasize that Advisory Panel (TAP), to assign appropriate priority to our efforts in practical applications are continuing. I this planning activity. Your participation, as in the past, would like to bring this to your attention as forcibly as I need not involve any financial burden on your research can. To this end, I quote from a letter that I recently sent contract support. to a high-level staff member of an important Con- 2. On a second matter, it now appears that high- gressional committee. It says, in part: intensity polarized H~ ion sources are sufficiently under- "I want to tell you about some unusual spinoffs stood that it is possible to choose the best one for from our basic research program, since I think LAMPF purposes. Again, as for the computers, this is a your committee may enjoy knowing about these. big-ticket item that must be budgeted over a number of "In collaboration with the medical community, years. But we must have a firm plan of what is required. techniques and instruments have been developed

6 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory which are used for heating human tissue with isotopes for biomedical applications are also localized radio-frequency current fields for the proceeding very well. Most of the dividends from treatment of cancer and the treatment of human science do not come immediately in terms of vision problems. As a direct result of this work, six keeping our country militarily and economically private firms in the United States have produced secure. The payoff usually follows the research by instrumentation based upon the Los Alamos many years. However, some of these dividends are prototypes, and a large number of human and paid very promptly and I just thought you might animal tumors have already been treated with this enjoy learning about a few of them with which you new method. Four U.S. patents have been issued to have, through your committee, been closely as- the Department of Energy and licenses have been sociated. granted to a number of private corporations. A "Although scenarios, such as the above, are number of veterinarians, county agents, and quite commonplace at Los Alamos and other state- ranchers now use this government-developed in- of-the-art laboratories, I have the feeling that strument to treat "cancer eye," a common disease sometimes they tend to get lost as elements in- in Hereford cattle [at least in this part of the fluencing 'he decision-making process." country and in other parts of the world]. An inexpensive, effective treatment for this animal Well, that is what I said to that gentleman. And to you disease even affects the price of beef. [Why do you I say that next month (December 5 and 6) we are think the price of beef is so low?] convening a miniworkshop to assess our practical- applications program and' to explore options for the "Los Alamos National Laboratory has loaned cancer therapy units to a variety of American future. Anyone who would like to attend should contact research institutions and a research hospital in Jim Bradbury. To make plans for the next 10 years, there Shanghai, PRC {People's Republic of China], will be some very good people here, not many, but very where neurosurgeons are using the instrumentation good ones—Richard Garwin, Ted Puck, Tom Tom- to treat brain tumors in humans [tumors that are brello, Al Clogston—to help us brainstorm. not treatable by other means]. As with the computer problem, we have now fulfilled our first 10-year practical-applications program. We are "Another spinoff has been a new technique for the treatment of vision disorders. We have de- going strong, but we want to ask the questions, Are the veloped a radio-frequency probe which is being things that we are doing really as good as we internally used at the University of Oklahoma to treat vision see them to be? And whether or not they are, Are there disorders. It appears that this new instrument may better ones that we should be looking at for the future? allow a large number of patients to undergo a relatively simple office-call procedure rather than have an expensive and comparably more danger- The Present ous corneal transplant. .. . "The hyperthcrmia instrumentation (for cancer Fiscal year 1984 should be another banner year. It treatment) developed at Los Alamos has resulted in appears that we have close-to-adequate funding to again commercial veterinary products from five com- operate for 3100 research hours, to continue support of panies located in Colorado, New Mexico, Arizona, all approved experiments for which beam time can be and Oklahoma. allocated, and to push strongly ahead with developments "More recently, we have learned that the Los presently under way and perhaps with one new Alamos R & D has led to the formation of a one—replacing the A-l target system, which is threaten- company in California, Arts & Science Tech- ing to present real problems to us. nology, Inc. This firm was organized to manufac- Again, in FY 1984 our budgetary situation was con- ture hyperthermia instruments for human cancer siderably enhanced by Congressional allocation of therapy; their products are based upon the Los $3 million of defense program moneys to operations and Alamos prototypes developed during the by the appropriation of additional moneys for nuclear 1970's. ... physics, some of which were earmarked for LAMPF. I "Our programs of practical applications related am also pleased to report to you that the appropriation to national security and the production of radio- of defense program moneys for support for -AMPF

November 1983 LAMPF USERS GROUP PROCEEDINGS 7 Los Alamos National Laboratory operations is now generally recognized as appropriate LAMPF UPGRADES (PAST) and will, I believe, become a continuing feature of future budgets, but in a way that will provide LAMPF with a I. High-Resolution Proton Spectrometer (HRS) single budgetary source—namely, Clarence Richardson, II. Biomed Facility Enloe Ritter, Jim Lease. They will have all these funds and can allocate them from their office. That is by far the III. Weapons Neutron Research (WNR) Facility best way to do it. I hope that this process will be initiated starting next fiscal year. IV. Neutrino Facility V. Isotope Production Facility

The Future VI. Radiation Damage Facility I

So the immediate prospects for LAMPF both scientifi- Vu-Graph 1. cally and budgetarily permit a measure of optimism. However, prudence as well as common sense dictates that even when the present looks tolerable, it is essential national security. All of these benefit from, and even to worry about the future; otherwise there will be no require, a high level of accomplishment in nuclear future. It is this we need to discuss much more intensely science as a means of furthering our understanding of the than we have at previous annual meetings. At issue are forces of nature and the laws by which they are our responsibilities and opportunities during the next governed. LAMPF is helping to discharge these respon- decade. By responsibilities I mean those (and here I will sibilities. paraphrase some of the things Pete Miller said) that have So what about the future? to do with national goals in science and technology, Even with all the improvements to LAMPF in the those that have to do with the health of our science, and past and those scheduled for the next several years, we those that have to do with the cultural values associated face the near certainty that LAMPF, as it exists today, with our discipline, because we are among the major will not provide adequate capabilities during the 1990s. custodians of nuclear science. Vu-Graph 1 shows some of the major LAMPF improve- We have now held three workshops on what we call ments made in the past; I have left out many minor ones. LAMPF II. I would like to take a moment and repeat to Vu-Graph 2 shows what we might be planning for the you parts of my introduction to the last of the work- future: shops, because it represents, as well as I can state it, my • neutrino facilities II and III; philosophical convictions and attitudes concerning the • a time-of-fiight and magnetic spectrometer; evolution of LAMPF. I know a few of you have heard this—my apologies to you—but most of you have not. All of us, as scientists and as citizens, have a continuing general responsibility to look ahead and plan LAMPF UPGRADES (FUTURE) for the future. This responsibility weighs particularly I. Neutrino Facilities II and Ml (1984) heavily on those of us with management duties, but it does not excuse the rest of us. The decision process is not II. Time of Flight and Magnetic Spectrometer (1984) always clear-cut or even completely rational, but it almost always tries to address knowledge, experience, III. Low-Energy Pion (LEP) Channel (1984) and wisdom. That is one reason for the workshop we Spectrometer held; that is also one reason you are here today. IV. Proton Storage Ring (PSR) (1985) What are our long-term responsibilities to the discipline we pursue? As I see it, we have a major duty to V. Helium Jet for On-Line Isotope Separation (1986) help develop and maintain the people base and knowl- VI. Neutrino and Pulsed Muon Facilities (1988) edge base necessary to advance the science of the nucleus and the derivative technologies. These impact VII. LAMPF II, Stage I (1991) our intellectual well being, our educational enterprise, our health, our high-technology civilization, and our Vu-Graph 2.

8 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory • the Low-Energy Pion (LEP) channel and pion In my opinion, the key to LAMPF II is achieving a spectrometer. These are now under way, they are consensus, among a substantial fraction of the nuclear not in doubt; and subnuclear science community, that LAMPF II is • the Proton Storage Ring (PSR), which is being built where they want to work in the next decade. But what is and will be completed reasonably on schedule; the basis on which we might hope to achieve such a • the helium jet for on-line isotope separation. This is consensus? in the talking and thinking stage, but I have high Our understanding of the structure and dynamics of hopes it will command funding and come to frui- the nucleus and its applications is still woefully inade- tion; quate. If you agree with that, as I suspect most of you • a neutrino and pulsed-muon facility. We had in- will, the next question is, What can we do about it? We tended during this year to make a proposal for this, know that different probes and therefore different facili- but have deferred it. The reasons are too lengthy to ties are required to reveal the various aspects of nuclear discuss here, but we want another year of consider- structure and nuclear properties. We also know that ation of where we are going with neutrino facilities, increased knowledge of the nucleus and the technology in which we are investing a lot of resources, and required to achieve this increased knowledge have led to with the pulsed-muon capabilities; and more and better applications of nuclear science and • LAMPF II. technology to medicine, industry, national defense, and The jewel of our future hopes resides in LAMPF II. And energy production, and to the accelerated study of mrny it is my considered opinion that without LAMPF II the other sciences. future, the 1990s, will become quite grim. Now I don't We have models that relate the systematics of nuclear think any of you can accuse me of trying to forward my properties to the structure of nuclei, which in turn can be own career by proposing a facility that will not run until related at some level to interactions of nucleons in a the 1990s. However, most of you will be around then, nucleus, to each other, and to the rest of the nucleus. and I urge you to give very serious attention to where However, we do not have a comprehensive and useful you want to go during the next decade. unified model of nuclear structure and nuclear reactions All right, what are our options? based on first principles, and we have yet to relate Frankly, one option is to continue with relatively convincingly any model to the constituents of nucleon modest improvements and hope that new, exciting op- structure. So, much remains to be done in the domain of portunities will emerge that can be addressed with the essentially classical nuclear science. capabilities at hand. To my mind, this approach would High-energy physics is different; it has focused on be irresponsibly risky. In view of what is at stake, I think discovering new particles, unifying the basic interactions, we are obliged to pursue the more conservative approach and determining the limits of symmetry and conservation of planning and implementing a new major capability. laws. It appears that the answer to some of these But what shall that be? fundamental questions may come equally well from the Any major endeavor, I remind you, to be successful lower energy domain, provided one can perform ex- must embody at least three characteristics. quisitely precise experiments, which, however, require beams of quality and intensity heretofore inaccessible. 1. There must be strong and enthusiastic indigenous The U.S. "flagship" of nuclear science, as LAMPF is support at the host institution. As you have heard identified in the Vogt Report, is still operating at full from Pete Miller and I'm sure you found out for steam, but it will start slowing down by the end of this yourselves by talking to many people here, this is decade as we bring to completion many of the major already true, in spades, at Los Alamos. experimental programs for which it was designed. It 2. The scientific community must be sufficiently seems clear that for LAMPF to continue to contribute to enthusiastic about the new initiative to pledge their national goals at an appropriate level during the next support and their efforts toward its implementation decade and beyond, a major improvement in capability and utilization. To determine the extent of this must be put in place. We must be cognizant of the support is one purpose of the workshops we have fact—this is very important—that the exploration and been holding. exploitation of the energy frontier are driving particle 3. Agency and Congressional support must be physics to colliding-beam experiments, which are ex- achievable. quisitely beautiful and absolutely essential, but which

November 1983 LAMPF USERS GROUP PROCEEDINGS 9 Los Alamos National Laboratory severely limit the number of experiments that can be Nuclear Physics Division of the American Physical addressed each year. Therefore, the major part of the Society. Now the reason I was persuaded to do this is education function will necessarily shift more and more that I was told by people I respect very highly that there to those facilities that not only work on very important is an unfortunate division, a rift in the nuclear science problems but also accommodate many groups simulta- community, between those who like medium-energy neously, as is now the situation here. physics of the kind practiced at LAivIPF and those who Well, that is what I said at the last LAMPF II are partial to heavy-ion or classical nuclear physics or Workshop. But what really matters is what you think other areas. I think this should not be permitted to and, even more, what you intend to do about it. The time proceed. It is very dangerous for the nuclear science has come when, if you want to impact the future of community and for the nation for such a thing to LAMPF, you will have to stand up and be counted. happen. And I was persuaded that if I would only take To properly plan for the future, we need a consensus this job (of course, there is a hope that I won't get on a course of action. The Board of Directors is working elected—nonetheless, if I am elected I will serve con- assiduously toward this, but they cannot and should not scientiously), I could help avoid this kind of division. It is come to a consensus without broad input from you, the very destructive and we must do whatever we can to Users of LAMPF, and from the rest of the scientific keep it from progressing. community. I know that a few of you—not very many, but a few of you—feel that the vein of ore we are presently mining is so rich that only relatively minor Extending Our Horizons improvements in mining equipment will permit us to fulfill our mission for the next 10 years. I happen to The most serious criticism I have heard pbout strongly disagree, but those of you who believe that LAMPF II is that the menu presented, although large should make that case as strongly as you can. Others of and diverse, does not contain enough really choice items you are convinced that nothing short of a full-scale and that can make a difference to the direction of physics. fully implemented LAMPF II, with its half-billion-dollar The best answer I can give is to refer the critics to the price tag and many experimental areas, should be put proceedings of the LAMPF II workshops. The last one is forward at this time. Well, those of you who believe that the most important, and the proceedings will be available should so advocate as strongly as you can. Still others of in December. There are a thousand pages of these you may be willing to settle for a staged approach as the proceedings, which reflect the thoughts of 300 eminent one that is most likely achievable. I happen to belong to scientists who participated vigorously and enthusias- that group. The point is that all opinions must now be tically in this workshop. vigorously, but expeditiously and fully, debated in the But let me say a little more than that. I have often hope that we can achieve a consensus with which our stated that in my opinion the greatest dividend that canonical constituency and also a reasonable fraction of LAMPF can pay is to present a great arena where the particle physics community can live and about which teachers and students together can teach and learn the we can all be enthusiastic. art and science of interdisciplinary problem solving. I still In order that our final decision reflect as fully as think this is our most important function, and we have possible the combined wisdom of the scientific com- been doing it. How can LAMPF continue to serve that munity, I am encouraging several initiatives, including an function? By continuing to attract some of the brightest invited paper session at the Washington meeting (and I and most creative scientists and students that our society understand that this will actually take place). Jim produces. How can we do that? By catalyzing very Bradbury and I have proposed that the Nuclear Physics exciting world-class research programs. So what does Division sponsor a workshop on the interface between LAMPF II offer that is so exciting? I will give a few nuclear and particle physics. The American Physical examples, again with the stamp of my own prejudices. Society has offered to have a 1-day workshop following LAMPF II, more than any facility proposal I know the Washington meetings, and that might be fine, but I about, will help to unify nuclear and particle physics by think in addition we need a 1- or 2-week workshop to addressing important problems from atomic to particle really explore this at an early time. physics. I have personally agreed to risk the ultimate I do not know of any options anywhere that are more sacrifice—to stand for election to chairmanship of the exciting and have the potential for greater impact on the

10 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory way we see the universe than testing quantum elec- Neutrino scattering and muon capture can be used to trodynamics, our most successful field theory, or than study the spin-isospin structures of the electroweak the scattering of neutrinos by electrons and the precise interactions, thus permitting investigation of CVC, measurement of the angular distribution in such scatter- PCAC, and neutral currents of the standard theory. ings. This is the way to study weak interactions in their It is not unreasonable to assume that there is a purest form. What greater discovery could anyone make transition region between the meson-nucleon and quark- than to identify neutrino oscillations or to measure the gluon degrees of freedom in nuclear matter and that this neutrino mass? The Russians claim, on the basis of a region is subject to exploration by hadronic probes of beautiful experiment, that there is a neutrino mass; I high quality, as would be generated by LAMPF II. Dick don't know. Silbar has pointed out that LAMPF II should enable The standard theory of electroweak interactions repre- study of hypernuclei under conditions that have the good sents a great advance but presents many puzzles. How possibility of providing signals that reflect the quark better to shed light on these puzzles than through the structure within nuclei. study of muon-number nonconservation? Do we know To those of you who get most excited by the discovery the momentum-transfer dependence of conserved-vector of a new particle, I would only pose the question of current (CVC) and partially conserved axial current whether it is ruled out that rare kaon decays might hold (PCAC)? I think not. Neutrino-electron scattering and some real surprises. Is it unreasonable to speculate about muon-capture experiments can help. The standard the- such things as axions or photinos? The point is that if ory assumes that neutrinos are massless and that lepton these particles exist, the best hope for finding them may flavors do not mix; muon number is supposed to be reside in LAMPF II. conserved. But these are assumptions and are not part of Finally, one must ask whether, in terms of operating grand unification as presently imagined. LAMPFII and construction costs, Los Alamos is an appropriate offers, in my opinion, one of the best chances, if not the place to build another large accelerator facility. The best chance, of testing these assumptions to meaningfully answer to this lies in the results of an in-depth study, high levels of precision. conducted 8 months ago, of LAMPF budgetary ex- Many people have recognized that the nucleus is a perience over a period of 6 years. Figure 2 and Vu- superb laboratory for the study of both strong and weak Graph 3 present some of the results of this study. I do interactions. This laboratory will be much enhanced by not have time to go into this here, but let me just say that the availability of intense, pure, high-quality beams of we built a model based on FY 1979 because that was the protons, pions, muons, kaons, and neutrinos at first year we really had budgetary pains. We followed LAMPF II energies. Quantum chromodynamics should through on all the different kinds of expenditures at have a field day, as should also Dirk Walecka's quantum LAMPF in their proper proportions to determine what hadrodynamics, because a major question is to confront, the escalation factor was year by year. Finally, we in a detailed way, the predictions of these theories with compounded these into a numerical figure that says by high-quality experimental data. The standard theory how much we have to multiply our FY 1979 budget to assumes universality—the coupling of a lepton pair to a have the same purchasing power as we had then, by the hadron pair independent of the flavor involved. How end of this fiscal year. Of course, we estimated using good is this assumption? 1984 and 1985 escalation factors. The matter of charge-parity (CP) nonconservation Vu-Graph 3 shows the compounded index. As you deserves much more study. Kaon decay affords op- will notice, Los Alamos, the whole Laboratory, is 1.74, portunity for such study. which is quite good in relation to the producer price There is presently impetus for building a heavy-ion index that is from data from the Department of Defense collider to study the quark-gluon plasma, and I support tables of major deflators. You also notice that LAMPF is this, but I would point out that such studies also might be higher than the Los Alamos Laboratory as a whole. That undertaken with intense beams of antiprotons. is because we use so much electrical energy. We use, The entire field of hypernuclear physics is wide open. when we run, as much electrical energy as all the rest of Herman Feshbach and Dirk Walecka have pointed out the Laboratory combined. However, what you should that by using the nucleus as a filter, that is, by identifying look at in asking about construction costs and operating specific final states, one can focus on a specific compo- costs is whether this number, 2.07, compares with those nent of a given reaction—just a marvelous possibility.

November 1983 LAMPF USERS GROUP PROCEEDINGS 11 Los Alamos National Laboratory FY 79 80 81 84 85

—— Operation* R««tarch —-.GPP AIP Capital

\ . Cumulative , fOver/(Under)-J Funding

-30 Fig. 2. LAMPF budgetary experience, projecting estimated escalation factors forjl984-85 (see text).

VARIOUS MEASURES OF INFLATION

FY FY FY FY FY FY 1979-80 1980-81 1981-82 1982-83 1983-84 1984-85 Combined3

LAMPF Operations 13.2 16.4 13.0 9.7 13.3 11.7 Model 2.07 Los Alamos 5.2 11.5 12.1 8.1 11.4 9.7 1.74 b BNL 8.8 15.0 15.0 8.5 8.4 9.8 1.86 b SLAC 10.0 13.1 14.9 7.5 10.2 12.3 1.90 Consumer Price6 13.5 11.6 9.1 5.8 6.0 6.0 1.64 Index Producer Price0 13.4 13.4 12.4 10.5 11.0 10.0 1.95 Index

'Comparison of the escalation rates is expressed as a compounded rate for the six- year period expressed as a multiplicative factor. "Trie SLAC and BNL figures are national laboratory composites provided by their respective Budget Offices. cData are from the Department of Defense table of major deflators.

Vu-Graph 3.

12 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory STAGES OF A PROJECT Los Alamos; (2) you, the Users of LAMPF; and (3) my spouse, who at this stage in our lives deserves a majority Unbounded Enthusiasm stockholder option as to what we do next. And she will Total Confusion have it (if she were here, she would say, "When?"). I simply do not know how much longer I will remain persuaded that I am uniquely and transparently useful to I LAMPF in my present capacity or how much longer it will be feasible for me, from a personal standpoint, to Disillusionment Onset of realism defer my next involvements. I do know that it is Search for guilty Renewed enthusiasm important, for many reasons, to identify one or more people with whom you would be comfortable and who Punishment of innocent Successful completion would be able and willing to assume directorship of this facility. A search committee, as Pete Miller has told you, Promotion of nonparticipants Scientific justification involving members of the LUGI Board of Directors, has Vu-Graph 4. been at work on at least a related problem. I know that your suggestions would be helpful and welcome and appreciated.

for the Stanford Linear Accelerator Center and I also know that if you are counting on my help in Brookhaven National Laboratory. You see that we do assuring the long-term future of LAMPF, it would be not compare badly with other major laboratories that are prudent for you to act expeditiously in making known known for their efficient operation; we compare really your priorities for the shape of that future. A coherent quite well. (The report containing this table is available, if effort by the LAMPF Users to make your case in you distrust my conclusions or wish to study it at your Washington is absolutely essential. leisure.) Finally, I would like to acknowledge a milestone, again So where do we stand with LAMPF II (Vu-Graph 4)? of a personal nature. I don't know whether all of you are I suggest that we are on the optimistic path. aware that Herb Anderson was given the Fermi award some months ago. I would just like to add my congratula- tions and I know you would like to add yours to those of A Personal Note the President of the United States, who presented this award to him. As a result of your great successes as Users of LAMPF and as a result of the fact that together we have invariably kept our promises and have always dealt with Questions After Talk the federal establishment with complete honesty and candor (we were not always right, but we were always Question: Can you tell us why it is very important at this truthful), we presently enjoy an unusual measure of good time for the Users to get more involved in our future, in will in the United States Congress and in other places as what we are calling LAMPF II? well. We can today be very effective in transforming our Rosen: As all of you know, the lead lime for new image into support for a consensus plan for the future of facilities is now very long, for a number of reasons I will LAMPF, provided it has DOE support. not go into. It is clear to me that by the end of the next But a good consensus plan is a sine qua non. I must calendar year fundamental decisions will be made about alert you to the fact that some of us are not getting any future nuclear and particle physics facilities in this younger, at least not noticeably. At my age, one starts country. If we miss that window, we may have to wait a seeing the world as divided, like ancient Gaul, into three long time for another chance. I therefore feel that the parts—one part will do whatever they can to keep you next 12-14 months are critical ones for us to get our act from retiring, another part wishes the hell you would, together and decide which way we want to go, and for and the third part couldn't care less one way or the other. you then to organize yourselves. We at Los Alamos will How much longer I will consider it useful to continue organize ourselves; Don Kerr, Pete Miller, and other with my present responsibilities must take into account senior members of this Laboratory will do their fair share the wishes of at least three factions: (1) my colleagues at in convincing whoever needs to be convinced that a

November 1983 LAMPF USERS GROUP PROCEEDINGS 13 Los Alamos National Laboratory beacon like LAMPF is really vital to a great laboratory Question: How are we going to overcome the opposition like Los Alamos. We will do that, but it will be of no of the Nuclear Science Advisory Committee (NSAC) to avail if the scientific community does not make its case LAMPF II? for basic science and education, and make it within the Rosen: It was clear from my conversations with both next 12 months. Enloe Ritter and Clarence Richardson that there is no way, even if it were appropriate, to bypass NSAC. They Question: Why was the proposal for a pulsed-muon are an official, legal player in this game and we simply facility deferred? must find effective ways to interact with them. I think we Rosen: Let me give you a summary of the reasons for have not found those ways yet. Again, the interaction deferring a proposal for a pulsed-muon facility. As we must not only be from people here, it must also be from looked at this facility, it became crystal clear that outside Los Alamos. Perhaps that could be our most without a neutrino facility to share the full cost, perhaps serious roadblock, because there are plenty of people in $30 million would fall on this one facility. As I talked to Washington who know what to do with the kind of my good friend Enloe Ritter, and others in Washington, moneys we are asking for, and if they can say, "Look, it did not take a genius to see that this kind of cost label NSAC is lukewarm to this enormous expenditure of on that kind of facility, which is only one-quarter nuclear funds," it would be enough to kill it. So NSAC has to physics, just did not fill him with the kind of enthusiasm come on board. to make him draw his sword and go forth in Washington You know I have talked with the members of NSAC. and lop off heads to get funds for us. That is one reason. They are all reasonable, competent people, and my So then you ask, Okay, why not ask the other three- feeling is that if the scientific community presents its quarters—atomic physics, particle physics, solid-state case, NSAC will listen. And if NSAC listens, DOE will physics—to contribute a fair share? Well, it is going to listen. With Congress there will be no problem. It's an take longer than we have for the next cycle to galvanize amazing situation, but that's the way it is. those communities into action, if it indeed can be done—a very difficult job. Those are the reasons.

14 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory OPERATIONS REPORT

Andrew Browman Los Alamos National Laboratory

Don Hagerman is out of town this year, as you know, so I will try to give a short summary of the highlights of our operation. The year 1983, as you have already been told, was a pretty good year for us. Vu-Graph 1 shows what happened during the year in terms of run cycles. Notice that the P~ beam now has an availability approaching that of the H+. For many years P~ availabilities have been 10% (or more) lower; the P~ source is now a mature source. Vu-Graph 2 compares last year's running with some previous years. The scale on the left shows the hours when the beam was actually hitting the target at production currents. A few years ago we took a dip in the number of hours, but we have held constant at about 3100h since then. The right-hand scale shows milli- ampere hours. The X indicates the number of hours that H+ beam was available in Area A this year. Since the amount of beam current delivered on target for both the WNR and the P~ beam is negligible, the lower curve actually is total H+ beam and is essentially the beam in Area A. Notice that the number of pions delivered has stayed constant, in spite of fewer hours. I hope this year that the number of hours will go up, that the current will again go up, and that you will therefore have more pions Andrew Browman than ever before.

FY 1983 OPERATION

Cycle Length Availability (%) Cycle (h) (mA-h) H+ H"

35a 800 430 80 89 — 36 828 506 94 91 82 37 860 476 89 80 90 38b 908 544 81 80 81

"Cycle 35 spanned FY 1982 and 1983. "Cycle 38 spanned FY 1983 and 1984.

Vu-Graph 1.

November 1983 LAMPF USERS GROUP PROCEEDINGS 15 Los Alamos National Laboratory LAMPF — H+ Beam on Target FACILITY HIGHLIGHTS —1983

woo - 1. 1200-pA test run in February at 10.5% duty factor 2. 900-|iA production running in cycle 39

3. Transition Region installed

4. A-2 target cell replacement

5. Staging area and remote-handling buildings complete 6. 67 different experiments set up and run I m Vu-Graph 3.

be able to count on that. The improvements to the facility represent intellectual challenges, complexities, and, unfortunately, expenses that are basically the equivalent of the largest experiments in the experimental areas.

1977 1978 1979 1980 '-581 1982 Figure 1 shows one of the facility installations; this happens to be the TR. It was a big job; there are 8 Vu-Graph 2. bending magnets, 12 quadrupoles, 12 steering magnets, and a pile of diagnostics that are working well. Of course, the bottom line on all these is the physics that we I do not see much chance of the running time of can do with these improvements. 3100h changing, as Louis has already told you, but I Vu-Graph 4, a picture shown on the operator's think we are making slow, steady progress in increasing console last week, shows the currents as they proceed the amount of beam delivered to the experimental areas. from the accelerator down the experimental area (the Vu-Graph 3 shows some cf the successes we have had current decreases as it goes through the targets). We are in this last year. The first one was a test run; we ran for a now able with the A-2 improvement to run a very thick couple of hours at well over 1-mA average current and at target at A-2, thus producing more particles there. I 10.5% duty factor. The machine and the experimental warn you that we do not produce beam in the A-6 area are now capable of handling powers approaching a region; you are now looking at the limits of the current megawatt. We have run for something like 3 weeks at monitor capabilities. 900 uA: this is production, steady running. Last week- Not everything goes as well as anticipated. As I end we reduced the current to 800 uA. We have vacuum mentioned before, although the A-2 repairs are looking problems in the A-1 target box. extremely good, the H+ beam came on about 4 or 5 A new Transition Region (TR) has been installed and weeks later than planned, and that resulted, as a good works well. The only people who are probably aware of number of you already know, in last-minute changes in this are those who were called out 2 days early at the the running schedule. Again, this points up the difficulties beginning of this run cycle when the production beam in remote handling. On the other hand, as Louis said, current was ready 48 h ahead of schedule. The A-2 target we've been able to perform remotely any repair in a cell replacement, made this last year, was instrumental in target box — it takes a long time, but we can do it. allowing us to get to these higher beam currents. Other things have happened. The staging area and NOVEMBER 1983 remote-handling buildings are complete. I noticed that Louis said 95 different experiments, instead of 67; he •974 LACM4 1ACM2 2ACM3 3ACM1 5ACM1 6ACM1 included WNR, too. We hope, of course, that further RP, UA902.9 898.8 820.9 687.8 687.1 688.6 work in the experimental area will allow us to run higher beam currents routinely, and I think we probably should Vu-Graph 4.

16 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory c o

DO .is E S u u J3

November 1983 LAMPF USERS GROUP PROCEEDINGS 17 Los A/amos National Laboratory Next, Vu-Graph 5 lists some activities that are either Let me now go back to the PSR-related activities. under way or being started; I am not going to cover them These activities are necessary to make the PSR facility all in detail, but show them to give you a feeling for what as transparent as possible to the present users. The PSR is going on around here now. I will talk in more detail facility needs a high-current H~ source, and that has about these Proton-Storage-Ring- (PSR-) related ac- been developed. We are now building a production tivities later on. Looking at the other ones, we hope to model; it will be installed and should begin operation by replace the A-l target cell. That is the only target cell April. We have a lot of beam-dynamics studies to do remaining that is still the way it was many years ago, and with the high-current source once it is installed; we will it is starting to show signs of trouble at higher beam be running it during production next year, debugging it. currents. After every 6-month running period, we always The new transport lines and the new switchyard are have a collection of problems that arise in each target cell necessary to make the time sharing of the beams to the — mainly water leaks, occasionally vacuum leaks. PSR facility and the rest of our facilities as noninterfer- There is a plan to rebuild the beam-stop area in 1985. ing as possible. This construction will occur next year We hope in the coming shutdown to start some signifi- and represents extremely large changes to the facility. cant work on both the spectrometer in the Low-Energy Once these changes are embarked upon, no beams will Pion Channel and the time-of-flight spectrometer in the go to any experimental areas until the changes are switchyard. We are working on neutrino experiments in completed successfully. We are committed to make these Line E and at the beam stop. (Line E, for those of you changes early enough that we can meet the PSR comple- who don't recognize the term, is the extension of Line D tion date, which at the present time is scheduled for April out beyond the Weapons Neutron Research area). The 1985. accelerator control computer conversion is just about This brings me to Vu-Graph 6.1 show this with some dene; we are starting now to transfer the FORTRAN trepidation; it is a possible schedule for LAMPF for the programming into the new control computer. It is hooked next year. The reason I show it with some trepidation is up to the accelerator, and I expect that this next year it that so many things are being done by so many different will become an essential part of the facility. people that it is more difficult than usual to predict exactly what is going to happen. I will be very surprised if this doesn't get changed sometime in the next 6 months. ONGOING AND NEW PROJECTS — 1983 As you can see, there is no H~ beam; those of you that take the tour down in the injector region will see a big 1. PSR-related activities hole where the H" injector used to be. We expect to turn off beam about the first of February, and during this time a. H~ ion source we think that repairs to the A-l target cell will be possible and that we will be installing and testing the new H~ ion b. New transport lines source. Beam will come back on in the summer, possibly c. New switchyard in July. At the present time the PSR people have informed us that they will be ready to take H~ beam 2. Replace A-1 target cell sometime in April 1985. If that is the case, we must shut down sometime in October to have enough time to make 3. Repair other target cells as needed the necessary switchyard and transport modifications to 4. Rebuild beam-stop area deliver beams in April 1985. That is basically what I have to say. With Vu- 5. LEP and TOFI spectrometers Graph 7,1 would like to warn you of something going on 6. Neutrino experiments (Line E and beam stop) in the experimental area right now. There are a tritium target and a very large liquid-hydrogen target in the 7. Accelerator control computer conversion experimental areas. We do not want uncleared people going in the experimental areas. You can tour the Vu-Graph 5. machine if you want to, but not the experimental areas. Thank you.

18 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory NOVEMBER 1983

LAMPF PRODUCTION PERIODS

.. 1983 1984 1985 AMJJASOND JFMAMJJASOND JFMAMJ

H+

START PSR CHECKOUT AND RESUME PRODUCTION AS POSSIBLE

Vu-Graph 6.

PLEASE NOTE

NO EXPERIMENTAL AREA TOURS ALLOWED

ALL VISITORS TO THE EXPERIMENTAL AREA MUST HAVE RADIATION BADGES

(TRITIUM AND LARGE LIQUID-HYDROGEN TARGETS IN USE)

Vu-Graph 7.

November1983 LAMPF USERS GROUP PROCEEDINGS 19 Los Alamos National Laboratory STATUS REPORT ON THE PULSED SPALLATION NEUTRON SOURCE AT THE LOS ALAMOS NATIONAL LABORATORY

Charles D. Bowman Los Alamos National Laboratory

Introduction Facility Status

The Los Alamos National Laboratory is constructing The WNR facility has operated well during the past a high-intensity spallation pulsed neutron source for year for both neutron scattering and nuclear physics neutron scattering and nuclear physics research. The experiments. About 60% of the beam time has been facility will accept beam from the Clinton P. Anderson devoted to the 5-us-long pulse mode for neutron scatter- Meson Physics Facility (LAMPF) and accumulate it in ing and about 40% to the 0.2-ns microstructure mode for the Proton Storage Ring (PSR) now under construction. nuclear physics. A summary of the operation for the The proton beam will then be ejected in intense bursts most recent running period is given in Table I. During and transported to a neutron-production target that will this period, WNR operation was restricted to nights and be an upgrade of the existing Weapons Neutron Re- weekends because of the construction of the building to search (WNR) target. The initial design objective for house the PSR. Clearly, the multiplexed magnet system, 1986 is an average neutron-production rate of the WNR beam transport, and the target are operating 16 1.2 x 10 n/s over 4n with a pulse rate of 12 pps. excellently with only 3% downtime. The construction of Figure 1 is our most recent drawing of the WNR/PSR the building to house the PSR will be finished ahead of facility. The principal elements for the future are identi- schedule. We received beneficial occupancy of the fied as the beam-transport channel from LAMPF ©, the magnet-ring hall in August. Proton Storage Ring ®, and the WNR target area ©. The experimental program has been going well. Sev- Major changes in the facility are planned that will eral new spectrometers operated very effectively, result- significantly change the appearance of the facility around ing in a major improvement in research productivity. the target. These are described,in this report. Presently operating spectrometers include a single- A neutron-scattering research program was begun at crystal diffractometer, a constant-Q spectrometer, a the WNR in 1982 at an average source intensity of beryllium difference spectrometer, and an electron-volt 3 x iO14 n/s. Research at the WNR will continue inelastic-scattering spectrometer, the latter in collabora- throughout the construction period, with primary tion with the spallation neutron source (SNS) laboratory. emphasis on developing new fields of research that can A general-purpose powder diffractometer will be brought be studied with intense pulsed neutron sources and on on line in 1984. construction of the new class of spectrometers required We have begun a formal user program this year for pulsed neutron-scattering research. We believe that starting with two instruments—the beryllium difference all elements necessary to complete a world-class center spectrometer and the single-crystal diffractometer. The for pulsed neutron scattering will be in place in 1986: an number of instruments in the program will be increased unsurpassed proton source, an optimally designed each year. At the end of 1986, 10 spectrometers should neutron-producing target, new space for accommodating be operational and two-thirds of the neutron-scattering experiments, and an array of new spectrometers specially research time will be available to outside users. designed for pulsed neutron-scattering research. Plan- Any user is eligible to apply for research time on these ning is under way for neutron-intensity enhancement by spectrometers. Proposals should be sent to Richard N. as much as a factor of 10 beyond the 1986 objective. Silver at Los Alamos. These proposals are then for- warded with comments to a joint review committee of

20 LAMPF USERS GROUP PROCEEDINGS November 7983 Los Alamos National Laboratory WNR FACILITY LOS ALAMOS NATIONAL LABORATORY © — HIGH-CURENT TARGET AREA ®— LOW-CURRENT TARGET AREA © _ PROTON STORAGE RING ® — CONTROL & DATA CENTER © — NEUTRON TIME-OF-FLIGHT PATH ® _ PROTON BEAM FROM LAMPF ®— 40-m EXPERIMENTAL BUILDING

Fig. 1. Overview of the WNR/PSR facility. With the completion of the PSR building

the Los Alamos and Argonne National Laboratories, Table I. WNR Operating Summary" which allocates the spectrometer time among the most (May 1982-February 1983). promising experiments. For the first running period at Time the WNR for the experimental progr; m this fall, 24 (h) (%) proposals were received for the 2 spectrometers and experimental time was made available for 18 of these. Scheduled operating time 3066 Beam available from LAMPF 2778 Beam available for WNR experiments 2696 Facility Upgrade Program for Neutron Scattering Overall availability 88 WNR efficiency 97 Many changes now under way will contribute to the development of the WNR facility into an international a Daytime/weekend-only operation because of PSR construc- center for neutron-scattering research. These include the tion. construction of the PSR, the upgrade of the target- moderator system for intense proton current and optimal

November 1983 LAMPF USERS GROUP PROCEEDINGS 21 Los Alamos National Laboratory neutron spectrum for several classes of experiments, a part of the experimental floor area, quiet rooms adjacent major expansion of the experimental area to allow to the floor for assessment of progress on experiments, comfortable placement of at least 15 spectrometers, a and space for data-collection systems. In all other computer-development program that will provide each spallation sources, the beam strikes the target in a spectrometer with a dedicated data-collection system, horizontal direction with limitations in spectrometer floor and a formal plan for developing the spectrometer array. space associated with beam transport to the target and Each of these efforts is discussed separately below. with target-servicing facilities. It is important in our planning to take advantage of our full circle of spectrometer locations made possible by the vertically Proton Storage Ring directed proton beam. Also, the arrangement should allow for a number of long (~200-m) drift tubes for The Proton Storage Ring (PSR) will enormously neutron nuclear physics. increase the power of the facility for both the neutron- The arrangement of the area is shown in Fig. 2. The scattering and nuclear physics programs. A comparison existing experimental hall will remain essentially as is of the two capabilities is given in Table II. Note that the except for some outfitting that will provide a better pulse width will be shortened by a factor of 20 and that environment for experiments. Two large halls are shown the intensity per burst for neutron-scattering experiments on the east and west sides of the present experimental will be increased by a factor of about 300. As mentioned area. Each hall is spanned by a 10-ton overhead crane. earlier, construction of the PSR is on schedule (the Space is set aside in each hall for a staging area. Support current status was summarized recently by G. P. Law- space is also provided adjacent to the experimental floor. rence1). An output-current level in the long-pulse mode An access channel from the northeast is provided so that of 20 uA is expected to be achieved at 12 pps by the fall a fork lift can be operated on the existing experimental of 1985; the full 100-uA intensity is expected in 1986, hall floor in the north, east, and south sectors. Generally along with substantial current in the 1-ns mode. By 1987 the experiments requiring the highest neutron intensity full operation in both modes is expected and work will will be located in the northwest quadrant of the existing begin on several PSR upgrade possibilities. experimental hall; the higher resolution systems and more bulky experiments, in the two outer halls. Note that the low-current target area identified as ® in Fig. 1, Additional Experimental Space where we now conduct moderator studies, etc., will be replaced by the west hall. The present experimental space at the WNR is totally Figure 2 shows 19 drift tubes, which are required to inadequate for the outstanding source intensity that will fully use the present and proposed experimental space. be available with the PSR. A plan has been proposed for However, the biological shield was originally constructed an increase in space by a factor of 5 to provide ample with only 12 drift tubes. It will be necessary, therefore, to area for a full array of spectrometers, a staging area as drill several new drift tubes through the 4.6-m- (15-ft-)

Table H. WNR/PSR Performance Characteristics.

WNR PSR

Neutron Nuclear Neutron Nuclear Scattering Physics Scattering Physics

Proton energy (MeV) 800 800 800 800 Pulse width (ns) 5000 0.2 270 1 Repetition rate (pps) 120 6000 12 720 Average current (jiA) 3 0.2 100 12 Average neutron rate (n/s) 4 x 1014 1.3 x 1013 1.2 x 1016 1.5 x 1015

22 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory LOWER LEVEL FLOOR PLAN -

Fig. 2. Ground-floor plan for augmentation of the WNR/PSR experimental area. The existing WNR target area at the center of the figure will be expanded with the addition of two large halls. New drift tubes to be drilled will increase the total for neutron scattering to IS; the 4 drift tubes in the southeast quadrant will be used for neutron nuclear physics research. thick 80% iron/20% concrete shield. A new drift tube Target, Moderators, and Shielding was drilled this past year to demonstrate that installing new drift tubes is practical. The four drift tubes pointing The intense PSR beam currents will require a com- in the southeasterly direction will be devoted to long- plete redesign of our present target-moderator system. flight-path nuclear physics experiments. This leaves 15 We must accommodate the needs of nuclear physics for flight paths for neutron-scattering research. Taking into 0.25- to 10 000-eV neutrons, cold moderators for both account the possibility of two spectrometers on some of neutron scattering and nuclear physics, and tailored the beam lines, it is expected that space will be available moderators for particular neutron-scattering spec- for 20 or more spectrometers. trometers. A large variety of moderators is therefore

November 1983 LAMPF USERS GROUP PROCEEDINGS 23 Los Alamos National Laboratory required. A target-moderator geometry now under con- the neutron pulse by the reflector. Calculations by sideration is shown in Fig. 3. Russell2 show that the neutron pulse is not broadened by A key element of this concept is a split target arranged the reflector beyond the 270-ns width of the proton pulse so that equal neutron intensity is produced in the upper from the PSR except at lower energies where moderation and lower segment and a relatively large volume of time in hydrogen dominates. uniform flux density is created that is relatively free of The clear separation between the moderator and the tapet-cooling paraphernalia. Several moderator types neutron-producing target is expected to be beneficial if therefore can be placed in this region to service different the facility intensity is upgraded by additional beam spectrometers. Isolation from background associated current, by emphasizing a 238U target, or by means of a with high-energy neutrons also should be optimized in fission booster. For a possible future fission booster the this geometry. A through-tube geometry is possible, reflector also could serve as a large heat sink for after- which might be valuable for some experiments. It also heat in case the target-cooling system malfunctions. In will be possible to use wing geometry if additional summary, this geometry allows 360° access to mod- moderator types are required. erators, separates moderator and target-cooling ap- The inner region of the target assembly is surrounded paratus, reduces streaming of high-energy background- by a beryllium reflector that in turn is surrounded by a producing neutrons down the drift tubes, creates a region nickel annular cylinder serving as a second neutron of uniform flux for placement of moderators, and reflector and as additional biological shielding. The substantially increases the effectiveness of the biological complete assembly is about 1 m in diameter and 1 m shield. The target-moderator system has been described high. We have addressed the question of broadening of in greater detail by Russell. 2

MODERATOR NICKEL REFLECTOR SHIELD

UPPER TARGET WING MODERATORS

NEUTRON* FLUX TRAP MODERATORS

LOWER TARGET

Fig. 3. Prospective WNR target-moderator-reflector assembly. The target consists of a split target surrounded by an inner beryllium reflector and an outer nickel reflector. The beam enters from the top. The facility can accommodate several moderators and also a through-tube flight-path geometry.

24 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Spectrometer and Data-Collection Development redesign of several of the critical power components it is hoped that 400 uA will be achievable at 48 Hz. The PSR Neutron-scattering research began in 1982 with sev- also will produce 1-ns bursts at the rate of 720 Hz and at eral exploratory spectrometers that performed suc- an average current of 12 uA. This latter capability is cessfully. Two of these, the filter difference spectrometer particularly powerful for million-electron-volt neutron and the single-crystal diffractometer, were brought into time-of-flight experiments. Initially the PSR will run in operation in 1983 as fully engineered spectrometers. either the long-pulse or short-pulse mode, but upgrading Adequate resources are expected to allow two additional to allow multiplexing of the two modes is under consider- fully engineered spectrometers to be brought on line in ation. The PSR has very attractive capabilities for a 1984 and 1985 and perhaps three or four in 1986. broad spectrum of experiments and it will be used for Therefore, at the close of 1986, 10 fully engineered experiments other than neutron scattering, although spectrometers are expected to be operational. Approx- neutron scattering will carry the highest priority. Pres- imately one spectrometer per yjptr will be added after ently the most prominently discussed additional pro- 1986. User input on the priority of instrument construc- grams include neutron nuclear physics, neutrino re- tion and user participation in spectrometer design and search, and muon condensed matter and nuclear physics construction will be solicited for spectrometers to be research. Such programs for spailation sources have installed after 1984. been reviewed in detail in a report by Dombeck.3 A brief The high average neutron intensity of the WNR/PSR summary of plans for the WNR/PSR is given here. and the low 12-Hz repetition rate will require the handling of very high instantaneous data rates from the spectrometers. A computer system to handle these rates Neutron Nuclear Physics is under construction. The system provides a data- collection computer for each spectrometer and a central The WNR/PSR will provide outstanding character- computer at the WNR/PSR for data reduction and istics for neutron nuclear physics studies from the analysis. A coaxial cable link to the Los Alamos ultracold neutron energy range up to 250 MeV. This is National Laboratory Central Computing Facility wis well illustrated in Figs. 4 and 5 prepared by Aucham- completed in 1983 that will make accessible to paugh,4 where the average neutron flux on a sample is WNR/PSR scientists and users world-forefront capabil- shown as a function of neutron energy. The optimum ity in data processing and the most advanced data- flight path has been chosen to allow a resolution of storage facilities. approximately 0.1%. The pairs of numbers in paren- In summary, a fully equipped world-class neutron- theses are the repetition rate and the flight path, respec- scattering facility should be operational in 1986 with tively. The numbers in parentheses after the facility 100 uA of 800-MeV average proton current at a repeti- acronym are the pulse widths. The curves for WNR tion rate of 12 pps. Ten fully engineered spectrometers show the capability with and without the PSR. The with a separate data-collection computer for each should facilities referred to by acronyms are located as follows: be operational in the newly completed and greatly ORELA (Oak Ridge National Laboratory), Gelina enlarged experimental space. At least three separate |Central Bureau for Nuclear Measurements (CBNM), moderators should be operational, each optimized for Belgium], KFK (Karlsruhe), and HELIOS (Harwell). different neutron spectral capabilities. A 238U target Note the enormous gain of the WNR/PSR over the probably also will be operational at that time. The WNR WNR and the performance of the WNR/PSR relative to will be conducting a full experimental program through- facilities elsewhere. Its greatest potential relative to other out the 1983-86 construction period, including an active sources is for experiments above and below the 10- to user program. 1000-keV range. At the lowest end of the range, the combination of a cold moderator and a mechanical Doppler system for neutron velocity reduction into the Other PSR-Related Programs ultracold range (about 7 m/s) will allow collection of densities of ultracold neutrons that might reach 250/cm3. The PSR is being constructed with components that A collaboration between the Los Alamos and Argonne should allow rapid upgrading to 200 uA at 24 Hz; with National Laboratories is under way to develop this for

November 1983 LAMPF USERS GROUP PROCEEDINGS 25 Los Alamos National Laboratory 1 3 ,-2 *IO° I0 10* I0 10* IO» 10' 10"' 10° >0f 10* NEUTRON ENERGY (tV I NEUTRON ENERGY (MeV)

Fig. 4. Fig. 5. Comparison of neutron facilities for the low-energy Comparison of neutron facilities for the high- region. The two quantities in parentheses represent energy region, presented as in Fig. 4. pulse rate and flight path to achieve maximum neutron flux in the energy internal AE for the given resolution. The quantity in parentheses by the Experiments now under way at the WNR in fission- facility name represents pulse width in fragment angular-distribution studies and neutron- nanoseconds. There are presently no plans for induced y-ray emission will be greatly improved. Nuclear operating the PSR in the 35-ns mode. data measurements, particularly those of interest to the fusion programs, will be greatly facilitated by the enhanced intensity. Depending on the degree of future possible use in a high-sensitivity attempt at measurement program development in million-electron-volt neutron of a neutron electric-dipole moment. nuclear physics studies, it might be appropriate to Neutron nuclear physics in the region below 1 keV has provide another target cell downstream from the PSR been relatively inactive in recent years, but the factor of and WNR where such measurements could be pursued 1000 advantage made possible by the PSR should be a 100% of the time. Preliminary studies indicate that it strong stimulus to this field. Studies, such as Doppler- should be possible to multiplex the short- and long-pulse free resonance neutron spectroscopy and resonance total modes of the PSR so that both classes or experiments reflection, and studies with polarized beams, etc., which could run simultaneously with separate targets. have not been performed thus far, should be possible. There is much in this energy range of interest at the interface of nuclear and condensed matter physics, and Neutrino Physics these two fields might well mesh here with mutual benefits to both. Since the WNR/PSR will operate 80% The attractiveness of neutrino physics using the in- of the time in the long-pulse mode, which is suitable for tense proton pulses and associated low duty cycle of the electron-volt neutron nuclear physics, an aggressive PSR has been well documented,5 and facilities for a program in this field would be possible. neutrino physics program are under development that For the million-electron-volt region, the WNR/PSR would eventually use PSR beam. A neutrino experiment will be operated in the short-pulse mode for approx- is being constructed at the end of the long channel that imately 20% of the time. Although this fraction is small, transports beam between LAMPF and the WNR. An the very high intensity can be used to pursue experiments additional beam-transport line is being built into this that cannot be done now or experiments that can be done channel that will allow LAMPF beam to be multiplexed in less time with associated increases in productivity. past the PSR and the WNR and onto a target for

26 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory production of muon neutrinos. The first experiments are amined to strengthen the Los Alamos National Labora- planned for 1984. An extensive neutrino research pro- tory research base. Promising programs include neutron gram can be pursued for several years with the LAMPF nuclear physics, neutron nuclear data, neutrino physics, beam while the PSR is brought on line and upgraded. and muon nuclear and condensed matter physics. It also After meeting the first PSR design objectives of can provide forefront capability for several branches of 100 uA in the long-pulse and 12 uA in the short-pulse nuclear physics research. Development of the PSR modes, the long-pulse capability will next be upgraded to research facilities in these directions will be pursued, with 200 nA, at which point 100 nA of beam would become highest priority continuing for neutron-scattering re- available for neutrino research. Further increases in PSR search. current to as much as 400 uA would be allocated to neutron scattering, to neutrino physics, or to both, in accordance with relative priorities and support levels. REFERENCES

1. G. P. Lawrence, "Los Alamos Proton Storage Ring," Muon Physics International Collaboration on Accelerator-Based Neutron Sources (ICANS) VII Proceedings, Chalk The facilities for production of muon neutrinos for River Nuclear Laboratories, Chalk River, Ontario, neutrino research naturally produce copious intensities Canada (1983). of pulsed muons. A low-duty-cycle high-intensity source of muons is highly attractive for use in condensed matter, 2. G. J. Russell, "WNR Targets and Moderators," atomic physics, and nuclear physics research. Studies by International Collaboration on Accelerator-Based Heffner6 indicate that muons can be collected and Neutron Sources (ICANS) VII Proceedings, Chalk transported effectively from the same target used for River Nuclear Laboratories, Chalk River, Ontario, muon-neutrino production so that studies using both Canada (1983). neutrinos and muons can be conducted simultaneously. It also appears that muon research and neutron nuclear 3. T. W. Dombeck, "Nuclear and Particle Physics with physics research could share the same target, provided High Intensity Pulsed Neutron Sources," Interna- that a separate target cell for this purpose were available tional Collaboration on Accelerator-Based Neutron downstream from the WNR/PSR. Sources (ICANS) VII Proceedings, Chalk River Nu- clear Laboratories, Chalk River, Ontario, Canada (1983). Summary 4. G. F. Auchampaugh, reproduced from the paper Much progress has been made in WNR/PSR facility "Status and Comparison of New, Planned, and development and in planning and implementing a full Upgraded Pulsed White Neutron Source Facilities research program since the last International Collabora- Since 1970," Nuclear Cross Sections for Technology, tion on Accelerator-Based Neutron Sources (ICANS) National Bureau of Standards Special Publication meeting. Construction of the PSR continues on schedule, 594(1980), pp. 920-928. a significant neutron-scattering research program is under way at the WNR that can continue through the 5. G. J. Stephenson, Jr., "A National Facility to Provide construction period, and a formal neutron-scattering user a High Intensity Neutrino Source," Los Alamos program was begun this year. The problem of National Laboratory proposal to the Department of bothersome backgrounds at the WNR has been solved, Energy, Los Alamos, New Mexico, December 31, and a versatile and effective target-moderator design has 1982. been developed. Plans are being implemented for spectrometer construction, data-collection and -analysis fa- 6. R. H. Heffner, in the "Proceedings of a Workshop on cilities, and a major augmentation in experimental space. Muon Science and Facilities at Los Alamos," Los Other areas of research besides neutron scattering Alamos National Laboratory report LA-9582-C, Los made possible by the PSR have been thoroughly ex- Alamos, New Mexico, March 15-18, 1982.

November 1983 LAMPF USERS GROUP PROCEEDINGS 27 Los Alamos National Laboratory STATUS OF LAMPF II

H. A. Thiessen Los Alamos National Laboratory

I will give you a report on progress since the beginning of the summer, including the physics that "we learned at the July workshop. One way of organizing the physics we would like to do at LAMPF II is to order it by the needed energy of '' e proton beam. This list is presented in Table I. One of the stars of the LAMPF II program will be muon-neutrino physics, which would be quite interesting if we had a 5-GeV proton beam. We could make a better muon factory than LAMPF, even with the 5-GeV beam. We would obtain variable-energy polarized protons and higher energy pions; most likely the nuclear chemists would see, in the first 5 GeV, the bulk of the changes in the reaction mechanism that occur between 1 and 10 GeV. At 12 GeV we get kaon physics [charge-parity (CP) violation is one of the important things—the study of the rare decays, the hypernuclei]; we get kaon-nucleon scattering; we get a way to study the spectrum of the hadrons, some of which are missing (low-energy K-N scattering has lots of holes in the data); we get kaon- nucleus scattering; and we have more flux of pions, H. A. Thiessen muons, and neutrinos. If we attain a 32-GeV class of machine, then we have a decent antiproton factory, we can have much higher energy kaons and pions, and a much higher flux of low-energy kaons than we would Table I. Physics at Various Proton Energies. have with lower energy protons. And if we have a machine above Brookhaven, then we begin to get into 5 GeV Neutrino physics new territory; we could have a machine with the capabil- Improved muon physics ity of the highest energy polarized protons available Polarized protons anywhere, as well as improved kaon and antiproton flux. High-energy pions What I saw in the July Workshop was the best Nuclear chemistry workshop ever held here on any subject. We brought in 10 GeV Kaon physics: charge-parity violation some new physics topics, including the high-p exclusive ± Rare decays processes that Glynnis Farrar talked about. We had Hypernuclei some fine talks on high-energy antiproton physics (high Kaon-nucleus scattering energy means well above LEAR but nowhere near the More flux of pions and muons collider energies). We briefly discussed extending the. energy range of polarized protons, and we talked about 30 GeV Antiproton physics glueballs. We learned that the long lifetime of the B Higher energy fCs meson and the apparent large mass of the top quark may More kaon flux make some huge differences in the details of our write-up of the kaon decays, but they may in fact make it even 50 GeV Higher energy polarized P more interesting. Better antiproton beams

28 LAMPF USERS GROUP PROCEEDINGS November 7983 Los Alamos National Laboratory PROPOSED LAMPFII LAYOUT SLOW-EXTRACTED BEAM X- ' ' EXPERIMENTAL AREAS ..THIN TARGET * * FACILITY

LAMPF H ACCELERATOR 4 STRETCHER

PROTON UTORAOe RINO |P8A>/ WEAPONS NEUTRON RESEARCH

t 100 100 300 400 SCALE IN f EET 24 JUNE «M3

Fig. 1. LAMPF II site layout.

You should receive the Proceedings of the Third 20% extra for contingencies raised the total to roughly LAMPF II Workshop about January 1. I would like to $500 million. We had a very expensive proposal as shown thank Tarlochan Bhatia (he managed to solicit from you in Fig. 1, and that did not include cooled antiprotons, every talk save one, which was held up in the French which may cost, as a wild guess, another $100 million. postal strike) and the Proceedings production staff. It is a At the end of the summer, the system consisted of the beautiful job—this is the best workshop we have ever following: we had a 32-GeV accelerator and its stretcher, had, and the best documented one. but we also had a booster. We did not know exactly what At the end of the workshop, we were talking about a energy booster we wanted, and still do not, but the 32-GeV machine, something like the biggest machine at proposal included a booster, and because of a need for 12 kG that will fit on the mesa. This machine is shown in polarized beam, it had a stretcher on the booster so the Fig. 1. It would be injected by H~ beam; it would be unused pulses of the booster could be used for variable- tunneled under the existing machine and would have four energy polarized proton beam. We have not carefully major experimental areas: a neutrino pulsed-muon area priced this, but it costs about the same to build a 32-GeV and three slow-extractive beam areas with a thin target machine with a booster or without. The big machine gets upstream. cheaper if we have a booster, but first we have to make up Our cost estimate for the 32-GeV machine was started the additional cost of the booster. before the workshop, but the numbers came out later. We The last day of the workshop I talked about a staged had a machine that cost about $130 million. We had a proposal; we would build the facility in several stages. stretcher that might cost half that, thus the total was $200 The first stage, for example, might be just the injection million for the machine and stretcher. We had four line in the neutrino area. The second stage might be a experimental areas at about $50 million each, with beams booster that could feed that neutrino area, and maybe it and detectors. So that gave us $400 million, and adding would have one experimental area in addition, with the

November 1983 LAMPF USERS GROUP PROCEEDINGS 29 Los Alamos National Laboratory booster set up so that the next stage, which would be a The first stage would be operational in 1991 or 1992; higher energy machine, could use the same experimental that means 1987 construction money, at the earliest. If area. And then we would add experimental areas and we submit a document requesting such a facility, there probably add the p's last. So, the features were: we had a would be no commitment beyond whatever is the first booster, we had a higher energy machine, we had several stage. I would say that at minimum, that first stage must experimental areas, and we build them one at a time. produce kaons. I would like to hear all of your comments Just before the workshop, the news hit that the Nuclear on this point, namely, that the first stage should at least Science Advisory Committee group making a long-range produce kaons. plan decided that there should be a heavy-ion collider, At present, we are trying to come up with the minimum and that such a collider represented a unique opportunity factory that we could build here. It would be at least a 12- in the area of nuclear physics. Given the constraints of GeV, 100-uA kaon factory. We have several ideas for that report, it is not possible to have two expensive reducing the cost. We can reduce the energy, which facilities, so LAMPFII was postponed for a very long means reducing the counting rate, and thus it may be time. I see no way, as the committee is now possible to eliminate the stretcher. Eliminating the constituted and the ground rules are now set up, to build stretcher would dictate that the duty factor be one-third the full facility, even in stages, because it is recognized instead of 1, but that goes with the counting rate and so it that ihe whole accelerator is going to be very expensive in is probably acceptable. And as you saw, if we had no the end, and what difference does it make if it is staged? money in the accelerator, it would still cost $200 million Now what does constituted mean? There are a lot of for the experimental areas, so we are thinking about ways things that could be constituted differently. I will let you to run with about half the number of beams talked about decide what that means. at the workshop. (I think we had 15 or 16 beams at the We must step back and ask, in some order, what does end of the workshop.) And we may be able to save some the country need? Let us say that it needs a next- money by reconfiguring the existing experimental areas. generation e+e~ or u+u~ collider somewhere. It needs a I remind you about the flux arguments. Figure 2 shows Desertron. I think we need some kind of a factory for a plot on linear paper of the kaon yield at fixed 1.4-GeV fixed-target physics that includes the physics we have secondary energy as a function of proton energy. You been talking about. We appear to need a heavy-ion can see that there is no sharp structure in the region collider, and we are already committed to a 4-GeV proposed. The kaon yield is about 5 times more at electron machine. What seems to have been decided this 24 GeV than at 10 GeV, so the first factor we have lost in summer is that the heavy-ion collider and the electron lowering the energy is the beam power, and then maybe machine are what we call nuclear physics. The high- another factor of 2 at most. It is a penalty we have to pay energy people will strip everything else off to get the if we lower the beam energy, but it is not a dramatic one, Desertron, even closing existing machines. And so we are and there is no clear threshold in the region 10-24 GeV caught in a crack, and that crack includes the fixed-target for kaons. For p's it is different. If we go down much programs and the polarized-beam programs at existing below 32 GeV, we lose fast on them's. machines. It is complicated because the problem might be Let us propose a 12-GeV machine like the one shown solved either by moving LAMPF II down toward nuclear in Fig. 3. It would have 10 times the flux of the existing physics or up toward high energy, such as making use of Brookhaven AGS slow-extracted beam, and 20 times the one of the boosters of the Desertron. Who knows whafs flux of kaons below 1 GeV. Of course at Brookhaven going to happen? But in any case there seems to be a plan they have to divide the beam many ways. We have to to get going on three of these, forget LAMPF II al- + divide the beam many ways; let us call that even. So as a together, and someday get to the e e~ collider. That is kaon factory, it is 20 Brookhavens. A 12-GeV machine is what the world in Washington seems to be saying. smaller, there may be a cheaper site, and we have a way What do we do in that rather discouraging situation? to do it with no interference with the PSR. Figure 3 is a Louis Rosen said we must have a staged plan because the scheme in which we reconfigure Area A; that means at whole plan will not sell; at the end of the first stage we least a shutdown like the Great Shutdown for Area A. must have a first-class physics facility that stands on its And in that picture, Areas B and C are not easily used own, the first stage should include an accelerator, and the after we go to LAMPF II. cost should be on the order of $150 million. If these To see this concept in its simplest form, let us put a conditions are met, there is some chance to fund it. ring, as shown, where it does not cross through the forest

30 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory When there are stopping beams, the energy is rarely varied. So this scheme might work for kaons even though l-cm CARBON TARGET they are coupled and even though it is an awkward arrangement for muon beams at existing meson factories. 1.40-OeV/c SECONDARIES The ".ext target cell might include two medium-energy beams, and two examples might be an EPICS II and the 1.8-GeV kaon beam. Anything could go there, but, I SANFORD-WANG + KR o looking at that target, they may have to be non-zero- PRESENT DATA degree beams independent of each other. The third target cell would contain the high-energy 10- beam. If the machine is only 12 GeV, then the beam would be about a 6-GeV nJC.P beam and it could share UJ 8- that target with a K° beam. Bob Macek has suggested putting a bending magnet right upstream of the target and aiming the proton beam toward the south side of the building so that 0° for K°'s points into a useful ex- 4- perimental area, and then bending it back to get onto the dump. There could be a muon beam produced at this 2- thick target. We would have the best duty factor and the best muon rate. There could also be a test beam at this target. So for the slow-extracted beams, we would get a 10 18 24 nice set containing most of the secondary-beam physics E PRIMARY (GeV) shown in the proposal. Another idea for the fast-extracted beam is to let it go Fig. 2. on down the same beam line, with rotating targets with Energy dependence of production cross sections on holes, or with the beam kicked around the upstream l-cm carbon target normalized to 10-GeV cross targets, or with slow- and fast-extracted beam scheduled section. during different time periods. In any case, there is a fourth target, which is used as a neutrino target and a pulsed-muon target. For neutrinos, there is a horn with of existing buildings. It could be built at the same the existing Line A as the decay region, putting the elevation as the present linac, and it could be injected off neutrino area downstream of the present beam stop. We the present Line B and reinjected into the switchyard with might even be able to use the Biomed beam as a pulsed- minimum trouble. We could then reconfigure Area A to muon beam if we add a vacuum chamber. So we have have some very useful beams in it. Should we decide to beautiful neutrino physics, beautiful pulsed-muon phys- have a booster for such a machine, there is a natural ics, beautiful kaon physics up to 6 GeV, and a facility location for it in the present parking lot for Area B, and providing a not-too-expensive, low-energy, variable- there could be an experimental area for the booster. energy polarized beam. If we choose to have no booster, Figure 4 is a blown-up drawing of Area A reconfigured we could put a jet target in Area B. Polarized proton for 12 GeV. It is conceptual only. The idea is to extract experiments could be done at variable energy by just from the accelerator at one point and to provide, down a watching what happens as the circulating beam energy single line, the capability of alternating pulses of a fast- changes. The beam could be polarized; we certainly will extracted beam and a slow-extracted beam. On the slow- design the accelerator for polarized protons. extracted pulses, which would have duty factor of about What does this scenario cost? Table II shows the one-third, the beam would hit th.r: first three targets. accelerator cost estimate. We scaled the cost estimate we The first target might be used Tor making a stopping had for the 32-GeV machine and came up with the K+ and K~ beam off the same target, with a first magnet following set of numbers, which says that for about $60 being a bending magnet common to both. This system million, we could build such a machine. We made a guess, gives very clean beams, and it is clear that there is a need not yet verified, that we really can have efficient slow for both stopping K+ beams and stopping K~ beams. extraction from a single ring that goes along with a lower

November 1983 LAMPF USERS GROUP PROCEEDINGS 3 1 Los Alamos National Laboratory I •5

E .2 1

32 LAMPF USERS GROUP PROCEEDINGS November 19B3 Los Alamos National Laboratory i r- C ii S3 MPF n AL AK£AS K1.II.HU/U 1M-M1 Fig. 4. A conception of Area A reconfigured for 12 GeV.

•5 « Table II. Accelerator Cost Estimate, October 28,1983. Dollars Accelerator (in Millions) Magnets and power supplies $ 15.8 rf system 13.6 Diagnostics and controls 12.0 Vacuum 6.0 Extraction systems 2.0 Fast dampers 1.5 Injection 1.4 Fast abort and dump 1.0 Collimator system 1.0 Bucket rotator 1.0 LAMPF injector modules 0.3 Installation 7.5 $ 63.1

Buildings 3 electromechanical equipment 5.4 15OO-ft tunnel @ $2000/ft 3.0 Support lab 2.0 Office for 100 people 2.0 Control building expansion 1.3 Ring entrance building 0.2 $ 13.9

Experimental-area modules See Table III 68.0 TOTAL 145.0 Contingency +20% 29.0 TOTAL (in 1984 dollars) $174 x 106

intensity overall, a lower beam power overall. It may costs for shielding, beam transport, etc., are shown. The have a booster with a similar total cost. We have not biggest single item is the beams, seven beams guessed at proved that we can do it, but we are working on it. $5 million apiece. The buildings are mostly mechanical equipment build- So we have a rather cost-effective experimental area ings for this new ring. We are making very good use of where at least half of the funds go directly into things we what we already have, so we need only a small number of want, namely, into the beams. By using Area A, we save additional buildings. shielding, beam transport, water, power, and buildings, Table III shows the cost of the experimental area. and we can use the existing remote-handling equipment; Macek suggests reworking about two-thirds of the steel the final savings is over $30 million. The total cost, and concrete that we already have. We add 10 kilotons including a contingency in this year's dollars, is about (kt) of new steel, some train—or canyon—fill (filling the $175 million, which is sufficiently close to Louis Rosen's trains containing the secondary beam lines out to a guideline of $150 million to meet his request. standardized cross section), and some new concrete. The

34 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Table III. LAMPF II Experimental Area Cost Estimates, October 28, 1983. Dollars (in Millions) Shielding installed $18 Cost Per Total (Kilotons) ton (in Millions) Reworked steel 20 $ 200 $ 4 New steel 10 800 8 Train fill 4 1000 4 New concrete 10 200 2 $18 Primary beam transport 6 Primary beam tunnel rework 1 Targets and target chambers (4 targets) 4 Rework beam-stop area and neutrino-area construction 5 Secondary beam lines (7) 35 Extend building 2 TOTAL $71

Questions After Talk

Question: I remember your talk about a 32-GeV ma- Question: One of the difficulties, I believe, is that NSAC chine and the three experimental areas. Why have you has told Washington that a heavy-ion collider has higher chosen only one experimental area? priority. Thiessen: It could be phase I of a higher-energy ma- Thiessen: I do not have a good way to face that problem. chine—those of us at Los Alamos know that we never We need your help. I do not propose to fight it. I think added another secondary beam, so the first plan had that if you believe the heavy-ion colliders are a good better have a good set in Area A. thing, there is some chance that is right and you should do it. I do not know what we will do; we could get in line Question: The configuration—could the 12-GeV ma- after the electron machine and heavy-ion collider. The chine inject a 32-GeV machine? real question is not physics. The reason our plan was Thiessen: Yes, I can see the two. If we have only one it is rejected, for the most part, was that the other was an a fine booster for the next one. Not everyone agrees that exciting nuclear physics prospect, and the committee is it is a fine booster, but it is usable as a booster for the next supposed to consider only nuclear things. Something is one exactly as it was located before. Nothing gets in the wrong with the system. way. Question: What is the add-on cost for a 5-GeV injector? Question: Would you comment on the choice of beam Thiessen: I do not know yet. Our first guess was that the current? total of a machine plus its booster is somewhere in the Thiessen: I used to say that the price of the machine was same bail park as a machine alone. It is more com- proportional to the current, but I think it is true that plicated, it takes more people to build it, but we save about half of the costs are fixed, so maybe half of the cost something on the big machine by having a booster. I can is proportional to the current, proportional to the energy, give you the details after we have done that cost estimate, or to the product of the two. That is about the machine not before. part.

November 1983 LAMPF USERS GROUP PROCEEDINGS 35 Los Alamos National Laboratory Question: What was involved in preempting a facility Question: What does the high-energy community think that accelerates heavy ions and produces kaons at Los of LAMPF II? Alamos? Thiessen: There is a high-energy problem as well. It is Thiessen: As you know, we once discussed that. The my belief that the high-energy community will shut off all right heavy-ion facility, if you think that one should be low-energy ~ ^d-target physics in order to get their built at all, is a collider, and you need some sort of coil'der. Th s not a physics question as much as the injector for that collider. LAMPFII would be the best view that "we really want to go for that high-energy injector for such a collider, whether it was a 30- or 60-Hz machine; we will do anything it takes." The high-energy machine. There are many pulses available to feed that community will shut off the AGS even though there is collider without much effect. It would take a new linac. universal agreement that we need a good factory for One of the big virtues of LAMPF II is that we are using stopping K's. the existing LAMPF for an injector; it is a beautiful injector. But we would need a new one for heavy ions. Question: What about Krisch's suggestion about a 50- And it would take a community that wants to use it; the GeV machine? community that you and I talk to here at Los Alamos Thiessen: I think we saw that 50 GeV would fit on the does not include the heavy-ion people. So we do not have mesa, but I'm not sure. the constituency here for a heavy-ion machine. That may be the biggest reason why it has not appeared so far. Question: What about the frequent changes of energy for LAMPF II? Question: From the- heavy-ion point of view, you say Thiessen: The real problem is to build a big enough team there is a real need for a collider, but there might be an to do a good cost estimate; we are nearly finished intermediate set that they need. To do a collider building building this team. We can afford changes only for a little you need more data, so planning may be done. longer because we must decide by spring, with your help, Thiessen: Yes, but why wait 10 years for that? The same what the energy and scheme of the first stage isto be. We data would be available with a heavy-ion injector for the must try that on the community in the summer, and give AGS. <° it to the DOE and the appropriate committees by the end of the year. That is our announced schedule.

36 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory PANEL DISCUSSION OF LAMPF II PROPOSAL

[Paraphrased and abbreviated]

Glashausser: The Science Policy Advisory Committee We will focus the discussion today on four things that was formed in 1983 by the LAMPF Users Group Board have been emphasized by the Policy Committee: the of Directors to review the LAMPF II proposal. Their machine concepts, the experimental facilities, the physics recommendations and suggestions will be discussed this priorities, and the strategy to implement LAMPF II. afternoon. The moderator of the discussion is Erich Vogt, At TRIUMF we think of kaon as an acronym for who will speak now. K mesons, antiprotons, other hadrons, and neutrinos. The question seems to be in part whether you are going to Vogt: Louis Rosen refers to this Laboratory as the build something primarily for kaons or a full-blown flagship of nuclear physics. You know there are facility that might cost $500 million. Between these proposals for kaon factories outside of the United States extremes one has alternatives and the question of how as well. We have another nautical image; think of the one is going to stage a facility. I am going to ask Alan flagship as being a sleek sailing ship and we're thinking of Krisch to make a few comments on that. the America's Cup. I don't think anyone wants to have a strong contender withdraw from the race. Krisch: At its first meeting, the Policy Committee rec- Now let me introduce the characters on stage. On your ommended that serious efforts be made to explore the left, we have the left-wing radicals, the provocateurs, possibility of a 100-nA LAMPF II of about 50 GeV. This from the Policy Committee: Dirk Walecka, Peter Rosen, would allow a large program of exciting and unique Alan Krisch, Leonard Kisslinger, Akihiko Yokosawa, research on the high-intensity frontier of particle physics Sydney Meshkov, Malcolm MacFarlane, and Lee Teng. in addition to the frontier program of nuclear and particle They are going to make statements to which the responsi- physics that could be done with a LAMPF II of about 15 ble people from the Board of Directors on the other side GeV. Some examples of the extra physics are high- are going to respond. On stage right, from the right, are intensity neutrino, antiproton, pion, and kaon physics in Harold Jackson, Jim Bradbury, Andy Bacher, Bob the 30-GeV range, and high-p± nucleon scattering with Redwine, Charlie Glashausser, Arch Thiessen, and spin. George Igo, and I'm Erich Vogt.

Dirk Walecka, Peter Rosen, Alan Krisch, Leonard Kisslinger, Akihiko Yokosawa, Sydney Meshkov, Malcolm MacFarlane, Lee Teng, Erich Vogt, George Igo, Arch Thiessen, Charles Glashausser, Robert Redwine, Andrew Bacher, James Bradbury, and Harold Jackson.

November 1983 LAMPF USERS GROUP PROCEEDINGS 37 Los Alamos National Laboratory We cannot deny the magnitude of problems associated transition from hadron to quark degrees of freedom, to with building a 100-uA facility of about 50 GeV. I will establish the structure of low-lying exotic states, and also mention three highlights of these considerations. (1) A to see high-/^ phenomena and exotic atoms. Finally, as a 30-Hz superconducting main ring does not seem sensible fifth category, we have meson-nucleus interactions; here because it would probably use about 200 MW of energy we need a high-intensity pion-beam facility for glueball in eddy-current losses. (2) The large main ring need not and meson spectroscopy and for studies of high-p^ be exactly in the present LAMPFI area because beam phenomena in exclusive meson-nucleus interactions. transport is really quite cheap. The 50-GeV ring might be either uphill where the mesas are wider, or down in one of Vogt: Thank you very much. The third statement is one the canyons, which is something that should be con- of the most important; it has to do with physics priorities. sidered by the LAMPF II staff. (3) The staged approach Louis Rosen said this morning that one needs to identify seems an excellent idea. With a booster of about 5 GeV the choicest menu items. Leonard Kisslinger has agreed injecting into a ring of about 50 GeV, there would be today to give his selection of the three-star physics to be some important advantages, including the following. done at the kaon factory. a. The main-ring repetition rate could be reduced to 5 Hz or less, and the rf would need little frequency Kisslingc' I am reporting on a subcommittee consisting modulation. These would significantly reduce the rf of Syd Meshkov, Malcolm MacFarlane, Fred Reines, Val cost. Fitch, and me. I want to discuss some of the three-star b. A physics capability of 5 GeV might begin around problems of international importance, many of which 1990, possibly in the present LAMPF I experimen- have come out of work at medium-energy accel- tal area. erators—Brookhaven's AGS, Argonne's ZGS, KEK in c. The booster could produce variable-energy Japan, and LAMPF. polarized protons in the 1- to 5-GeV range. In strong-interaction physics, the first group of three- d. Phased-in costs over a longer period might help the star items has to do with the revolution in particle approval of the entire project. theory. We now picture a theory in which there are quarks and gluons as quantum chromodynamics; nuclear Vogt: Thank you, Alan. Next, Aki Yokosawa will tell us physics is now playing and will be playing an important about experimental facilities for the highest scientific role. priorities. The first important part of this program is meson and baryon spectroscopy. In spectroscopy, the three-star item Yokosawa: I would like to quote briefly the conclusions is the glueball—these are quarkless excitations of the made by Peter Rosen, Peter Parker, and me. These vacuum. Then you have two-baryon physics. The three- facilities are associated with five kinds of physics and I star item goes under the general category of dibaryons, will mention those five in random order. First is a the six-quark states (approximate eigenstates) of neutrino facility, including the high-intensity neutrino chromodynamics. This is a complementary program to experimental area and neutrino detectors, enabling high- the National Electron Accelerator program studying the statistics experiments on neutrino and antineutrino elec- six-quark cold phase in nuclei. Then there is the high-/?^ tron scattering, neutrino-nucleus interactions, and neu- spin physics and high-p± nonspin physics. At the trino masses. Kaon-hyperon physics is a second cate- LAMPF II Workshop, Alan Krisch discussed this very gory, with high-intensity K beams up to 10 GeV/c, and nice theory. The goal is to find the effective quantum also a stopping K beam. Those facilities will be for studies chromodynamics (QCD) Hamiltonian. of charge-parity rare decays, stopping X's with hydrogen The second three-star item is hypernuclear physics, and other targets, hypernuclei, and K+ nucleus scattering. where we make y*'s, the strange baryon resonances, in The third kind is antiproton physics; we need enriched nuclei. We know how interesting that is from what was beams, and then a polarized antiproton beam, which done at LAMPF; in the 1970s we learned about delta would have to be developed. The facility would be for pp propagation in these interactions. This has many of the reactions, possibly quark-gluon plasma, and the Jl\/ elements of the entire three-star program. scattering amplitude from the nucleus. Fourth, for Next comes the electroweak-interaction theory. We nucleon-nucleon physics we need a variable-energy dealt with this three-star item this morning, and we feel polarized nucleon facility up to 6 GeV for study of the that it is presented rather well in the LAMPF II proposal,

3 8 LAMPF USERS GROUT- PROCEEDINGS November 1983 Los Alamos National Laboratory which covers rare K decays and CP violation, and scientific approval for a national electron accelerator. It neutrino physics. Our feeling is that this is a crucial item has also established priority for a heavy-ion collider. The in building our community interests in medium-energy high-energy physics community through the High- physics with nuclear and particle people. One should Energy Physics Advisory Panel (HEPAP) and the think seriously about a kaon flux 100 times the AGS Division of Particles and Fields (DPF) has recently kaons. established their top priority; it is my perception that once they set priorities, they will do what it takes to get Vogt: Before Dirk Walecka talks, let me make one or there and eliminate what appears to detract from that two remarks as moderator and a person from the outside. goal. I think it would be very foolish to take a position of I will end with some questions. First, where is the despair about the kaon-factory aspirations in the United scientific representation of the people meeting here as States or about the long-range plan being cast in stone. users of this facility? Second, where do working inter- There was a romantic movement for something called a mediate-energy and high-energy physicists see their fu- heavy-ion collider that excited a lot of people; it excited ture? Third, how can a users group such as this make an me. On the other hand, it still remains to be seen whether interest develop? I do not have the answers, but it is that will make a concrete proposal and whether the absolutely essential that there are some. 1 would physics can be obtained with any machine one can paraphrase Louis Rosen's comment this morning, that it propose (I think it would be). is essential for the Users Committee to make a coherent Also, I think the high-energy physics community at case in Washington for the future of LAMPF II. present is caught up in the euphoria of the SSC (Des- ertron), which is likely to get funded rather early because Vogt: I invite the people at the front of the room to make of pressures from Europe and because of election year. comments now, and then we'll open it up to the audience. Once that occurs, I do not believe that the high-energy physics community is going to want to put all its eggs in Jackson: We seem to be moving in the direction of a one basket; it is going to take a much firmer interest in staged program; is there a three-star area of physics that things like the high-intensity frontier. should have such high priority that it should drive the In addition, I do not believe that in the United States staging? the imperatives of the national laboratories will fail to be recognized, which are to keep strategic national laborato- Kisslinger: Yes, from the three-star list, it would be kaon ries such as this one operating in a very vital way; nor do decays and neutrino beams. I believe that the users behind LAMPFII will fail to grab the ball and run with it. With that, I want to ask Dirk to MacFarlane: We have learned one thing in nuclear speak on strategy. physics in the last 10-15 years—you cannot just build an accelerator and do experiments in isolation. You need all Walecka: Let me give you a few observations, most of sorts of different probes. If nuclear physics gets itself into which already have been said in one form or another. a bind building a new electron accelerator and closing First, I think the physics motivation for LAMPF II is down everything else but a heavy-ion collider, the proper very strong; it involves both nuclear physics and particle use of the electron accelerator would not be possible. We physics. One of the strongest arguments for LAMPF II is need hadron probes of the greatest variety obtainable, up the variety of probes you can bring to bear on important to, say, 15 GeV. physics questions. We should not lose sight of what you can do with the many types of probes—we are talking Question: Do you think by going to this particular about LAMPF II being complementary to what you can energy that substantial numbers of high-energy-particle do with electromagnetic probes (say, at an electron people would be more interested in a LAMPF II? accelerator) and with heavy-ion probes. These are com- Krisch: Yes, with a 50-GeV high-intensity machine one plementary ways of studying the questions involved. would have a frontier capability for doing elementary- The nuclear physics community, represented through particle physics. There are, as you know, 30-GeV ma- the Nuclear Science Advisory Committee (NSAC) at the chines that have been around for some time and can funding agencies and the Division of Nuclear Physics easily expand to considerably higher intensity. The only (DNP) in the American Physical Society, has given machine in the range of 50 to 70 GeV is Serpukov, which

November 1983 LAMPF USERS GROUP PROCEEDINGS 39 Los Alamos National Laboratory does not have very high intensity. I feel that high px, were mentioning completion around 1994; that is 10 which is one thing you can reach with high intensity, is an years from now. We must be careful when we are important frontier capability. Certainly not 100%, but planning a machine so that we do not build in some bias some fraction, perhaps about one-half, of the high-energy toward cutting off later stages; 12 or 14 GeV has that physicists will not end up at the Desertron. problem.

Teng: It is very obvious that at higher energies the Kisslinger: There has been a beautiful unification of number of facilities is low. The Desertron is really one physics in the last 20 years through the quark-gluon experiment. It is not possible to put in enough crossing theory. My feeling is that we should call for a 50-GeV regions for all the high-energy physicists looking for high-intensity accelerator. In the physics we already quarks. know, a large part of the interactions involve spin. We know that gluons are very much related to spin and Question: What are the costs of the first stage? magnetism.

Thiessen: We have not finished the cost study. However, Freedom: When do we let reality in? We are now talking I heard Lee Teng say that our first-guess estimate for 32 about 50 GeV; are we going to get the money from the GeV was $140 million, which was about $70 million high-energy physics community? I doubt it. above what I was talking about. Vogt: The NSAC did not say that this physics was not Question: I want to make a comment about the staging interesting. It looked at two other very interesting op- approach. It was essentially unanimous that the first tions, and put one ahead of the other. It said, in addition, stage should go above kaon threshold, that it should be a that we need to keep a watch on how these projects kaon factory. develop. If you want to view that as an NSAC rejection of the kind of physics aspirations that we have, I think Teng: I would like to add a general requirement to the you are dead wrong. staged approach. Each stage has to drive the next. MacFarlane: That was a slightly evasive response. It is Vogt: If you have a 30- tc 50-GeV machine in mind and true that the NSAC priorities are not engraved on tablets you want to build a booster, probably you would not of stone. On the other hand, if one puts forth a proposal make it 12 GeV. You would build a 5-GeV machine, and for a $500-million 50-GeV accelerator without any then 50 GeV. change in the internal constitutions of the funding agency, it will just sit there for so long that the accelerator people Teng: If I were to aim for 50 GeV, I would pick a 3-GeV may have to look for other things to do with their lives. booster. Thus, the physics argument already pushes it up One can ask about the possibility of a reversal of NSAC's to 5 (or better, 12) GeV. But then the next stage is a recommendation. Unless it becomes clear that the esti- factor of 4 only; that is not cost effective. mates of the energy density created in 50-GeV heavy-ion colliding beams come out to be way off, I would say the Thiessen: If you break the machine somewhere around chances with the present NSAC are essentially zero. I 4 GeV ± 1, the second stage costs half as much per watt. don't know about the next NSAC, obviously. On the That was one of two cost-saving features of the booster other hand, because the present NSAC is a fair represen- approach. The other one is that the aperture of the second tation of the community, representing the people who get stage is likely to be smaller, but that has to be tempered money from the nuclear physics section of DOE, the next with our recent desire to add slow extraction to it. We committee is likely to agree with them. I do agree that assumed it would be smaller, and we came out with the reality has to be in the discussion here; reality is that same total cost. $500 million is not now available from nuclear physics.

Meshkov: I'd like to make an issue about the merits of Vogt: Let me give another answer. At the meeting when the staged approach. It would have to do with sociology. the priorities were hammered out, the high-energy I think a machine around 3 GeV is silly. Maybe we physicists were asked whether they would contribute to should get up to some higher number; how about 11? We your kaon factory. Charles Baltay was there, and he had

40 LAMPF USERS GROUP PROCEEDINGS November 19S3 Los Alamos National Laboratory just come from Woods Hole amidst euphoria with the Kisslinger: I see the quark matter in three ways: (1) cold- SSC (Desertron). His response was, as I remember it, "If quark matter seen with electron scattering; (2) hot-quark you ask them for $60 or 70 million, you might be talking matter with heavy-ion colliders, which is a very interest- business—if you ask them for the bulk of $250 million., ing subject; and (3) warm-quark matter. When we have the answer will be no." Mind you, that was said when an antiproton entering a nucleus, what is the temperature they were talking about closing up Fermilab and SLAC of the quark matter that forms? It is certainly going to and devoting all their resources to a single laboratory. It have quark-matter form, but it is not the phase transition is not useful to take up discussions with the High-Energy to the quark-gluon plasma. Committee until after the SSC is more or less on the way. After that, one could try to get a joint high-energy/ Vogt: Perhaps the LAMPF II proposal has suffered nuclear meeting to review the proposal, to take another from the effective way that LAMPF I has been able to pass, and to see how much high-energy physics there is in argue in Washington for its own funds. The Users have it. not gotten involved in defending the programs here as much as they might have. The Users now must get Freedom: This is very ecumenical, but I take the more involved in the way they have in other projects. naive view that LAMPFII is clearly lower priority. Krisch: I heard from several people the implication that Vogt: It's not written in stone. the total amount of money available is fixed, and that one or another institution is going to get it. I don't agree with Freedom: No, it's written on paper. that; that is not a proper way to think and is self- defeating. It is certainly self-fulfilling. If the people in P.Rosen: I agree with Barry. One of the elements of Congress and higher up hear us talking that way, they're reality is the tunnel at Brookhaven, with an experimental quite apt to accept it. If a number of physicists in different hall and other facilities at a cost (research and develop- areas of interest can all make an excellent case for their ment, plus actual construction) of about $200 million. I program, it strengthens the whole field. I also agree with think we will have a very hard time with either the high- some of the comments I heard earlier that one really does energy physics community or the nuclear physics com- have to come to terms with the tunnel on Long Island, munity, or some combination thereof, in persuading and until that is done in the proper way, both high-energy Congress to provide money for the SSC or an electron and nuclear physics are going to suffer. It may turn out machine or a heavy-ion collider or for anything else, until that putting a heavy-ion collider in there is really the best some good use is made of that tunnel and facilities. This is thing to do. the essential reality that affects both the high-energy physics community and nuclear physics community. Richardson: I'd like to ask about who it is in Washington that keeps getting mentioned. You don't want too many Kisslinger: In any case, the decision is going to be made people knocking on our office doors and telling us what in stages. We do not have a proposal for the heavy-ion we are supposed to do. I don't think that helps, because collider. We should be developing the best LAMPF II we are paying attention to your committees. You are proposal here. But I agree with MacFarlane about the talking about going to Congress. Do you really want $500 million not being available. The next stage will your decisions to be made in the political sphere? consist of looking at those proposals and the physics; there must be other committees looking because these are P. Rosen: There is a lot of first-rate physics that would very big proposals. be classified as nuclear physics, and there is a lot of first- rate physics we would classify as particle physics in the Redwine: In the midst of all this strategy, I have a LAMPF II plans. But somehow the impression has got- mundane physics question. Twice today, including in this ten abroad that the dominant interest at LAMPF II is in session, I heard the comment that high-energy anti- particle physics, and that is a fundamental problem. The protons might compete with heavy-ion colliders in creat- case has not been made strongly enough to the nuclear ing quark-gluon plasma, and I must admit that I was not physics community that there is indeed associated with aware of that possibility. LAMPF II very important, first-rate nuclear physics.

November 1983 LAMPF USERS GROUP PROCEEDINGS 41 Los Alamos National Laboratory That could be the heart of our problems in relation to could be done. For instance, I have to ask, can we get NSAC. such a machine funded? Is it going to satisfy enough of the community so that it will be viable? Kisslinger: I'd like to respond to Peter's comment. The problem is not nuclear vs particle physics. We are not Vogt: The single highest three-star item on their list was going to learn very much more about the ground state of kaons. That I think is clearly possible. nuclear matter in a conventional way. There are new aspects of nuclear physics; the problem of quarks is part Kissingler: Most of the three-star stuff is accessible if we of a physics problem, a nuclear physics problem. Your get high enough kaon flux. Glueballs are probably ruled proposal did not emphasize enough the strong interac- out, so we lose that aspect. The two-baryon quark tion. physics could be done. However, then you have a nuclear-particle facility and it is questionable whether one MacFarlane: There were all sorts of arguments in which could attract particle-physics support. LAMPF II proponents were not being heard by some people on NSAC simply because the committee thought MacFarlane: The message is clear that if you build the an attack was being made on their recent decision. On the 12-GeV accelerator, you have a beautiful facility that other hand, the LAMPF people (and this is clear at this could be sold to the nuclear community without too much meeting—I have heard this several times) have not done difficulty, but you would lose a sizable amount of the enough to study what it is that the main group of nuclear high-energy physics interest. Alan says that we should physicists is capable of listening to. I think they are not simply assume zero-sum games for money. Is there a willing to listen to and be excited by the beautiful nuclear vibrant new community that could generate its own new physics that one can do with LAMPF II. But you have to source of funding that does not come from direct com- understand just what they think is the central topic of petition with HEPAP or NSAC? nuclear physics. Many nuclear physicists feel they are in the business of studying the response of many-hadron Krisch: It is important to build a variety of first-class systems to external probes and to probes made internally, facilities that have unique capabilities to probe in different like the delta. If you can state it in those terms, then you directions. To put all our eggs in one basket seems very will get people to listen. You can say, for example, that unwise; if one can come up with a LAMPF II or an LAMPF has done magnificent work, forcing attention on AGS II proposal for a first-class, unique facility, there is the creation and propagation of the delta in the nucleus, a good chance that more funding will become available. and kaon physics can do the same thing in terms of Y*'s But if one cuts too many corners, the physics is less and excitations with strangeness. Nuclear physicists will exciting, and there is a fair chance we will not get listen to that. anything.

Hintz: Leonard, would you be willing to state your three- Vogt: At NSAC this summer, we heard a statistic on star list of nuclear physics with LAMPF II that was dollars for nuclear physics in various countries. It is a neglected in the LAMPF II document? factor of 2 lower in the United States than in Germany, France, Switzerland, Canada, and most of the countries Kisslinger: The three-star list in strong-interaction phys- with which the United States is competing. ics includes quarks, gluons, dibaryons, high-p^ spin, hypernuclear, few-baryon, and meson spectroscopy. All Romanowski: I remember that way back when the AEC these will have a big impact on our understanding of was running basic research, high-energy physics was not quantum chromodynamics. separated. Maybe we are in a good position to demonstrate to Congress that these divisions are artificial. I Igo: If we build a 12-GeV high-intensity facility, it would think nuclear physics is different now because there are be a beautiful facility; it would do excellent work, work quarks and gluons. If we had a kaon factory, wherever that has not been done. I have not heard the board placed, it would be a rich machine that would develop its address or discuss that particular proposal. You have own group of both particle and nuclear physicists. Nu- gone ahead and talked about a high-energy facility; you clear physicists and particle physicists have essentially have not addressed the things that Arch brought up that

42 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory one goal in mind. And of course to do that, we have to Kisslinger: I am very optimistic; I feel very good about have some understanding in Washington. what has happened to nuclear physics—things are going extremely well, intellectually. I feel worried about particle Vogt: I want to put George Igo on the spot and ask what physics. It sounds like a funny thing to be worried about, he, as Chairman of the Users Group, is going to do about but without CBA (at Brookhaven) the opportunities are getting the message out about LAMPF to the whole narrow. One wonders about young particle physicists in nuclear physics community. the country. The planning for LAMPF II should not be too narrow. I think we should be very open-minded and Igo: That is a very important question. I agree with get plenty of particle-physics input. In fact, if the particle Clarence Richardson that it is not a political question, but physicists have strong arguments that we should have at a question of getting physics discussed and our organiza- least 18 GeV and more intensity, we should really listen. tion seen as a very active and energetic organization that wants the facility. One suggestion from Louis, who thinks P. Rosen: I disagree with some of these points. In the of most things before any of us, is for a workshop in high-energy community, SSC is certainly the biggest Snowmass this summer about this area between particle game in town, but not the only game. You have, after all, physics and nuclear physics. It looks like we may have an Fermilab with the Tevatron II program, which is a invited session at the Washington American Physical program of fixed-target physics that is starting right now; Society meeting, in which we would discuss this interface; you have TeV I, which is due to come on in a few years also we may have a 1-day workshop after the Washing- and will be a colliding-beam program at 1 TeV. Then at ton meeting. Stanford you have the SLC program. If you're optimistic, you will have a very viable program of physics at 50/50 Wallace: I would like to comment on the transition in GeV e+e", which will explore the Z° region. So to imagine nuclear theory. Nuclear theorists want to know how to that the high-energy physics community is sitting out build nucleons out of quarks and then how to build the there saying our only choices are going to be SSC or a nucleus out of nucleons so you get a nucleus out of kaon factory is, I think, a complete misconception. They quarks. Now I hear proposals for machines, but I do not have many options open to them. LAMPF II is a understand yet what experiments they are going to do. proposal that comes out of what is described, for better or That has to be articulated. worse, as the nuclear physics community. To persuade the NSAC and the community as a whole that Baer: I cannot see that we would have just the electron LAMPF II is something worthy of their support, you machines and maybe the Indiana cyclotron, and have must show them how it relates to their interests. Granted that be the end of traditional nuclear physics. The that interests may have evolved from 1960 through 1984 capability of high-resolution pion and kaon scattering as from nucleons to quarks and gluons, "nuclear science" is well as proton scattering strengthens the entire nuclear the way the community will lend to define itself; that is physics program at the other accelerators and the whole the body forming your main support. There is a lot of nuclear physics community. That is the tie with tra- interest in particle physics, and if the AGS is turned off as ditional nuclear physics. Then we also have the point of the particle physics machine, one would hope that a view that Kisslinger is pushing, and that is quarks and reasonable fraction, maybe 10%, of particle physicists the connection to high-energy physics. We have to use eventually would find it attractive to work at LAMPF II. both of these arguments. We have to convince the nuclear But we have to keep in mind that the essential community physics community about the importance of LAMPF II. that will provide the base of support defines itself as the nuclear physics community. Redwine: I am very sympathetic to Wallace's idea that it is very helpful to have specific experiments in mind. In all Phillips: I do not understand how this nuclear physics honesty, I've been shocked the past year while looking at community that I know suddenly decided that they want the experiments proposed in connection with the electron to put their graduate students on that colliding-beam facility and the heavy-ion facility; they don't seem to be a heavy-ion machine. deciding factor.

November 1983 LAMPF USERS GROUP PROCEEDINGS 43 Los Alamos National Laboratory Baer: I agree with Gerry's comments. Many physicists fact that an accelerator of that sort might well not have a certainly have enormous hesitation about signing up for broad program. It was a high-stakes gamble that we felt an experiment on the UA1 scale. Actually, one of the we had to take. It was not a close vote, and it was not a reasons we went to nuclear physics rather than particle statement that LAMPF II would be dead. That was physics is because of the smaller scale of the experiment. never, in any sense, in our minds. Otherwise, we would So how was the NSAC decision made? not have been able to make that decision.

MacFarlane: It was not a meeting dominated by heavy- Vogt: What people do about this particular love affair is ion enthisiasts, but dominated by people like me, Steve going to unfold in its own way. It is not going to help us to Vigdor, Ernie Moniz. Erich Vogt—people in the middle. polarize the community by attacking the collider. We Now the thing that really turned people on was the idea should leave this meeting feeling we have a strong physics that there may bo a different state of nuclear matter that case to make for our own proposal. It stands a good we can get to, or at least the possibility of studying chance for a variety of reasons, and some of those hadronic matter under completely different conditions. reasons were heard today. And finally, the users must go We felt that if we were really interested in many-body out and talk about the ideas they want to pursue with problems, we could not turn our backs on that. We were, LAMPF II. I want to thank the Science Policy Commit- however, concerned about people getting into an uncom- tee for discussing these issues, and all of you for listening fortable experimental style. We were also aware of the and responding this afternoon.

44 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory NEW APPROACH TO POLARIZED PROTON SCATTERING BASED ON DIRAC DYNAMICS

Stephen J. Wallace University of Maryland

Important measurements of proton-proton and neutron-proton scattering observables at 515-MeV laboratory kinetic energy at TRIUMF and>proton-proton measurements at 579 MeV at SIN5 have led to reasonably sharp determinations of all the needed nucleon- nucleon phase shifts to about 600 MeV.6 Work at LAMPF has provided high-precision proton-proton data to 800 MeV, and experiments are now beginning that will provide tht; missing measurements of neutron-proton spin-dependent observables. In the foreseeable future, sharp determinations of both the pp and np amplitudes to 800 MeV will permit more high-precision tests of multiple-scattering theory. The most significant tests to date have been for 500-MeV p + nucleus scattering. Two complex amplitudes, / and g, are sufficient to completely describe opin-I/2, spin-0 proton nucleus scattering, where g is the amplitude for spin-dependent scattering,

(1)

The three observables are the cross section

a=|/l2+!*l2 , (2) Steven J. Wallace the analyzing power

2 2 Introduction A \f+ig\ -\f-ig\

Recent events compel a fundamental change in our thinking about proton-nucleus scattering. Measurements = 2Re[f(ig)*]/v , (3) of complete sets of observables for elastic scattering of 7 spin-1/2 protons by selected spin-0 nuclei have and the spin-rotation function provided the first high-precision tests of nuclear multiple- scattering theories. These tests are based on the impulse Q = 2Im[f(ig)*J/<, . (4) approximation and rely upon knowledge of nucleon- nucleon scattering amplitudes at energies where obvious All three have been measured at the LAMPF High- corrections to the impulse approximation have his- Resolution Spectrometer. Note that the analyzing power torically played a minor role.3 involves the difference of two cross sections, since

November 1983 LAMPF USERS GROUP PROCEEDINGS 45 Los Alamos National Laboratory CTt - if+'Sl1 is the cross section for scattering of a (5) proton polarized in the +n direction (normal to the scattering plane) and c j = \f- ig\2 is the cross section In Glauber theory,9 one obtains essentially equivalent for scattering of a proton polarized in the -« direction. amplitudes, since the eikonal approximation is reason- As shown in Fig. 1, both of and o| exhibit similar ably accurate at the energies in question. The optical diffraction patterns that can be thought roughly to arise potential U++ is predicted (in the impulse approximation) from differing diffraction radii for the two spin channels. to be Although the individual diffraction patterns are simple, they are interleaved in a way that produces considerable A-\ oscillatory structure in the analyzing power Ay and spin rotation Q. The proton-nucleus cross section a is the average of a f and a \ and hence is less sensitive to spin X\A Z C effects. lab - Jr lab

where ® denotes a folding operation and where A and Nonrelativistic Impulse Approximation lab C/ab are spin-independent and spin-orbit nucieon-nucleon amplitudes in the Pauli spinor representation, In the Kerman-McManus-Thaler (KMT) theory,8 the proton-nucleus amplitudes are obtained by solving a f =A+ iC(o + c ) + B 5, • a Schrodinger equation with relativistic kinematics, NN ln 2n 2

For nuclei with spin-0, the B, D, and E amplitudes that involve flip of a target nucleon's spin cannot contribute to the elastic-scattering optical potential. Once the AW amplitudes are known and the matter densities are fixed (for example, using electron-scattering data for the proton density and reasonable assumptions about the neutron density), there are no free parameters.

Figure 2 shows proton-nucleus observables o, Ay, and Q for 497-MeV p-40Ca scattering together with predictions of the KMT impulse approximation.1 The cross section is quite satisfactorily predicted by the impulse approximation; however, the analyzing power Ay and spin rotation Q are in substantial disagreement with the experimental data. There are several possible causes for such a breakdown of the impulse approximation for spin observables, one of them being the possible modifications of the free AW amplitude due to the nuclear medium. Particularly at lower energies (100-200 MeV), effective AW interactions have been found to substantially improve some impulse- approximation results for inelastic proton scattering.10 Another possibility is relativistic effects. Fig. 1. Spin-up cross section a j (solid line) and spin- down cross section o | (dashed line) for 500-MeV p-40Ca elastic scattering.

46 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory a. o

10* 10 20 30 ec.m.(de9)

Fig. 2(a)-(c). Proton-nucleus observables for 497-MeV p-^Ca elastic scattering based on KMT impulse approximation (Refs. 1 and 34). o o

Dirac Impulse Approximation

Analyses of proton-nucleus scattering have been performed over the past 10 years by B. C. Clark and L. G. Arnold and collaborators"'12 based on a phenomenological approach employing the Dirac equation. This Dirac phenomenology used typically 12 parameters -I whose values were fixed by fitting the proton-nucleus (cleg) data. cm. The phenomenology was not predictive in the sense of the KMT impulse approximation; however, when spin observables became available, a very suggestive predic- A more fundamental basis for the Dirac tion did emerge. Fits to the two observables a and Ay phenomenology has been discovered in the past year that based on Dirac phenomenology provided successful permits all the free parameters to be eliminated.13 In this predictions of the third Q (Ref. 11). No such natural formalism, one solves the Dirac equation with a combina- linking of spin observables was found in the tion of scalar (S) and vector (V) potentials plus a small nonrelativistic calculations. tensor potential (T) as foliows:

November 1983 LAMPF USERS GROUP PROCEEDINGS 47 Los Alamos National Laboratory {Ey° - y . p - S(r) - fV(r) - 2iy° y • r T(r)} V^= 0 Typically, the scalar potential has a large negative real part (200-400 MeV, attractive) whereas the vector poten- (8) tial has a large positive real part (200-400 MeV, repulsive). This feature now is seen to come directly from Energy E = \Jk2 + m2 is fixed in terms of the incident the Dirac AW amplitudes of Eq. (9) when these are momentum k. The potentials are predicted from nucleon- calculated from nucleon-nucleon phase shifts. There are nucleon amplitudes in the Dirac-spinor represen- profound consequences for nuclear physics. 14 15 tation - • In the first parameter-free Dirac calculation,17 the small tensor term of Eq. (8) was omitted. The results for 5OO-MeV/5 + 40Ca are shown in Fig. 3. The cross section shows minor differences from the nonrelativistic results; (9) however, the spin observables^y and Q are dramatically improved. Note that there are large relativistic effects at and nuclear densities small scattering angles and thus at small momentum transfer q ~ 1-2 fm"1. The energy transfer is strictly zero, since E is fixed in Eq. (8); thus the four-momentum transfer is also small.

V(r) = (10b) Comparisons of Oirac and Nonrelativistic Ap- proaches

One important feature of the relativistic and T(r) = (10c) nonrelativistic approaches is that they give the same results in Born approximation provided that the target nucleon wave functions have the "free" ratio of lower to In Eqs. (10a)-(10c) the on-shell AW amplitudes Fs, etc., are invariant functions of the ene' y and four-momen- upper components. This result follows from the definition tum transfer. These amplitudes a. folded with scalar, of the five Dirac amplitudes of Eq. (9) in terms of five 4 vector, and tensor nuclear densities based on Dirac Pauli amplitudes of Eq. (7) for free AW scattering. ' single-particle wave functions for the nucleus as follows: It is instructive to see how this works when the AW amplitudes are approximated by their forward (9 = 0)

values: Fso, Fv0, etc. The key relation is the connection 111 (lla) between the Dirac and Pauli amplitudes 0

2/+1 (12) Pvfr) == V (lib) m 4TI

2/+1 2m(EL + m) V (lie) o 4n . (13) where 0 indicates an occupied single-particle state and where u0 and !>0 are the corresponding upper and lower Then one finds under the stated conditions components of the Dirac wave function. In a nonrelativistic mode], one has ps = pv and pT = 0, since ~Us,(k') Us(k) there are no lower components. Relativistic Hartree wave functions predict that the l\ part of the baryon 16 (14) density pv contributes 2-3% to the normalization.

48 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory 1.0

0.0

- 1

: (*» -10. I,I, 10 20 30

Fig. 3(a)-(c). Results for 500-MeV /? + 40Ca elastic scattering based on Dirac impulse approximation (Ref. 17).

+ where U *(k,k') is the Fourier transform of Eq. (6) and = Us,(p'J us(p) ,(15) where us(k) denotes a positive-energy, free Dirac spinor. Equation (14) shows the equality of the Born approxima- which is just the statement of the equivalence of the Born tion for the Dirac and the KMT impulse approximations. approximation in relativistic and nonrelativistic theories.

The A/A - 1 factor is intrinsic to the KMT approach. Thus if UDlrac is a local potential in the sense that it Note that the Dirac scalar and vector amplitudes occur depends only on (p-p1)2 in momentum space (r in in the linear combination mFS0 + ELFvl) in the scalar coordinate space), then UKur(p,p') cannot also be a local amplitude A^ab and thus there are strong cancellations of potential because of the momentum dependence of ihe the attractive and repulsive parts. Dirac wave functions ufp) and u(p'). This means that There are three sources of difference between rel- solving the Dirac equation with local potentials as in ativistic and nonrelativistic results. The first is a different Eq. (8) automatically builds in certain nonlocalities from treatment of nonlocalities in the optical potential. The the point of view of the KMT approach. KMT potential is given in momentum space by

November 1983 LAMPF USERS GROUP PROCEEDINGS 49 Los Alamos National Laboratory + + The second and third sources of difference between U ~[E + Er- U ] U provides a fundamental dif- relativistic and nonrelativistic results are both associated ference from nonrelativistic optical-potential approaches. with virtual pair effects. In momentum space, it is Ths virtual pair effect induces nonlinear density de- straightforward to rewrite the Dirac wave function as an pendence in the impulse approximation that is not small. expansion in terms of the positive- and negative-energy The third difference between relativistic and solutions of the free Dirac equation as follows: nonrelativistic results is the use of Dirac single-particle wave functions for the nucleus. This effect is significant but not large, as most of the qualitative difference Us(?) (16) between Figs. 2 and 3 can be accounted for in Dirac Then one finds that the expansion amplitudes ty* obey calculations based on equal scalar and vector densities, coupled equations, ps(r) = pv(r), which eliminates the effects of the lower components.18 (17) Some further understanding of the nonlinear density dependence induced by solving the Dirac equation is and obtained by casting it into the form of a mathematically equivalent Schrodinger equation.19' Defining a wave (18) function

++ where U is the positive-energy potential discussed S~V above and where U+~, U~+, and U~~ are similarly defined. For example. in terms of the upper component u^(f) of the exact Dirac 1 '.p) Xs = Us, (p ) vs(-p) (19) wave function vf^(r) defined by Eq. (8), one can show that $%(?) is a solution of the Schrodinger equation The potentials £/++, U+~, etc., are two-by-two matrices 2 7 involving the Pauli matrices. The coupling to negative- {V + k -Vc(r)-Vs(r)o.L} ^(f) = 0 , (21) energy states is not small when there are large scalar and vector potentials present, and thus \|/~ is not negligible. where the central and spin-orbit potentials are defined in The amplitude y~ corresponds to backward-in-time terms of the Dirac scalar and vector potentials S(r) and propagation of the proton through negative-energy states V(r). For simplicity, the tensor potential is omitted; of the free Dirac equation. In Dirac's hole theory, the however, it may be included as shown in Ref. 12. negative-energy states are all occupied and \|/~ is re- 2 2 interpreted as forward-in-time propagation of a virtual Vc(r) = IE V(r) + 2m S(r) + S (r) - V (r) + VD , (22) antiproton. In the language of Feynman diagrams, vj/" arises from virtual pair effects. VM. * V'(r)-S'(r) (23) It is convenient to eliminate \y~ by solving Eq. (18) S(r)~ V(r) ' and substituting the result back in Eq. (17). This procedure yields a single equation for the positive-energy part and of the Dirac wave function, and this part contains all the scattering information, since asymptotically far from the = J [B'(r)lB(r)Y - i B"(r)/B(r) (24) nucleus the potential vanishes and only \j/+ can be nonzero. The equation for *|/+ is where

S(r)-V(r) (20) B(r) = 1 + (25) E + m Nonrelativistic approaches contain only the U++ poten- Because the upper component Dirac wave function tial, which is linear in nuclear density in the impulse contains all the scattering information as r—>• oo and approximation. It is clear that the virtual pair term because s(r) = u%(?) outside the range of the potential,

SO LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory has the same scattering information as the full Multiple-Scattering Theory Based on Dirac Dirac solution. The equivalent Schrodinger equation Propagation exhibits the extra density and energy dependence that arises in the Dirac dynamics as compared with the Of the various differences between the Dirac and nonrelativistic formalism. The KMT optical-potential nonrelativistic results, perhaps the most interesting is the analysis (in its local form) is equivalent to solving virtual pair contribution. This contribution raises the Eq. (21) with only terms that are linear in density issue of how couplings to negative-energy states can be l Vc~2mS(r)+2EV(r) and Vs~r' (V-S')/(E + m). predicted based on the impulse approximation, which The quadratic terms S2(r)-V2(r) are of relativistic uses only positive-energy AW amplitudes as input. origin and they become comparable in size to the linear The answer is that one must have an underlying terms at low energy. The spin-orbit potential is amplified dynamics in the form of meson theory to unambiguously by the factor (E + m)l[E + m +S(r) - V(r)\ ~ 1.5 at low predict the negative-energy couplings. The form of AW energy in the Dirac dynamics. Both of these effects amplitudes chosen in Eq. (9) provides an analytic ex- depend on the presence of large, opposite-in-sign scalar tension off the positive-energy mass shell that is (1) and vector potentials of dynamical origin. compatible with existing meson theories of the AW force, A classical argument shows how the very important and (2) free of kinematic singularities. However, it does spin-orbit form involving vector minus scalar parts not account for the most general off-shell behavior of the 21 comes about. The vector potential in the Dirac equa- AW amplitude. tion is like a Coulomb interaction. Therefore an "elec- In this section, we outline some basic notions that go tric" field E = -VV(r) is present in the nuclear rest Frame. into a Dirac multiple-scattering theory based on an Transforming to the rest frame of the moving proton, a underlying meson theory dynamics. The theory embeds "magnetic" field B = v x E is seen to be present and this the basic physics that has led to the Dirac impulse gives rise to an interaction -jl • B with the proton's approximation. It eliminates ambiguities and extends the magnetic moment £ = o/2m in (units ft = c = 1). The 1/2 approach to other areas of proton-nucleus interactions. relating spin s = 1/2 5 to the Pauli matrix a is canceled Nucleon-nucleon scattering is successfully modeled in by the protons' g factor of 2. a Lorentz-invariant fashion by solving the Bethe-Salpeter These effects yield a spin-orbit interaction -r~xV'(r) equation,22 the Blankenbecler-Sugar equation,23 or the O'7xp/(2m2) involving only the vector potential. This Gross equation,24 using as input relativistic meson- argument must be corrected for the effects of the Thomas exchange forces.25 Considerable phenomenology is re- precession, wT = 1/2 a x v. of the proton's rest frame quired to fit AW scattering data using meson theory; for when it experiences acceleration a. Both the scalar and example, ad hoc form factors are generally used to avoid vector potentials cause acceleration of the proton: divergences. a = -V[S(r)+ V(r)]/m. The correction to the spin-orbit For our purposes, the important points are that meson energy due to the rotating frame is -<3T • 1 = theory provides a Lorentz-invariant formulation and a rl \S'(r) + V'(r)\c • f xp/{4m2). '/Vhen these two effects well-defined quasi potential for AW scattering. The are combined and multiplied by 2m2/(E + m), one has the fundamental linkage of the meson theory to an underly- Schrodinger spin-orbit interaction r~l\V'(r)-S'(r)\~s • ing quantum chromodynamics (QCD) is not understood, L/(E + m) involving the vector-scalar difference. and it is assumed that some of the "mesons" are simply Thus the spin-orbit interaction is mainly due to providing a convenient parameterization of the QCD Lorentz invariance in the presence of scalar and vector interaction for intermediate-energy nuclear physics. potentials. In Eq. (23) the Dirac spin-orbit interaction is With such considerations in mind, the nucleon- amplified by a factor (E + m)l[E + m + S(r) - V(r) ], nucleon / matrix is introduced based on the Gross which comes from virtual pair effects. These effects also reduction scheme where one particle is on-mass shell in have a classical interpretation in that the presence of a intermediate states as follows: vector potential modifies the energy E to E - V(r) and the presence of a scalar potential modifies the mass m to 2m\[+)(p) m + S(r). t = v + v 2E(p){y«\E- (26)

November 1983 LAMPF USERS GROUP PROCEEDINGS 5 1 Los Alamos National Laboratory Here, v is a quasi potential defined so that the t obtained Here, H is the target nucleus Hamiltonian, MA is the rest by solving Eq.(26) produces the free AW scattering mass of the nuclear ground state, amplitude. To a good approximation one may think of v as the sum of one-boson exchanges. However, in general, more complicated contributions are also involved. A key point is that Eq. (26) is only slightly different from the and KA(p) = EA(p)-MA. The energy shift KA(p) + H / matrix for scattering of a Dirac particle by a fixed represents the energy carried by the nucleus in inter- potential PF. The recoil energy, mediate states much the same as K(p) is the recoil energy in the nucleon-nucleon /matrix. We shall refer to 2 K(p) = \fpTm - m , Eq. (28) as a Dirac-Watson multiple-scattering expansion. representing kinetic energy of the on-shell nucleon, goes For elastic proton-nucleus scattering, one needs the to zero as w —* oo. This limit defines the fixed potential nuclear ground-state matrix element of T, namely case. Furthermore, the positive-energy projection oper- <0| T|0> = Tm. In an optical-potential formalism, Tw ator \\(p) for the on-shell nucleon goes to unity for the obeys an integral equation involving the elastic optical fixed potential case, as does the kinematic factor potential Uoo as follows in the proton-nucleus cm. frame, 2m/\2E(p)\. Thus, asm-*oo, Eq.(26) reduces to the fixed potential t matrix, obeying

1 , = vc + iv (27) - m + (31) Similarity of Eqs. (26) and (27) shows that nucleon- nucleon scattering is equivalent, within recoil corrections, where U is defined by the multiple-scattering series to scattering of a Dirac nucleon from a static mesonic quasi-potential setup by the target nucleon. V !, . (32) In proton-nucleus scattering, the incident proton scat- ters from the quasi potentials set up about each of the nucleons in the target nucleus. Provided that certain Here, TjQ and GQ are as given by Eqs. (29) and (30), crossed meson exchanges are neglected (as they are in except for the presence of a projection operator in the nonrelativistic theories), a multiple-scattering description propagator that disallows the nuclear ground state as an based on Dirac dynamics can be developed in a straight- 26 intermediate state. Equation (31) is analogous to the AW forward fashion. The proton-nucleus t matrix is written quasi-potential Eq. (26), except that now the nucleus is as an infinite multiple-scattering series of the Watson on-mass shell. form27 The impulse-approximation optical potential corresponds to retention of just the single-scattering terms in the optical potential of Eq. (32) and approximating them (28) in terms of the free AW amplitudes. With appropriate kinematic factors. where impulse _ -4nik T, = V| + f, G T; (29) m and where G is a recoil-corrected Dirac propagator for 2 ? the proton x V <0\F(q ,S) • i10> (33)

1 G = where/1 is given by Eq. (9). Note that a local approx- y°[E-H -KA(p)]-y -p- imation to the AW amplitudes is used in which F (30) depends only en momentum transfer q and the invariant

52 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory energy s. Straightforward analysis of Eq. (33) leads to arises entirely from the free AW amplitudes.14 Various Eq. (10), which has been seen to succeed in predicting points shown are phenomenological values based on polarized proton-scattering observables. Extension of fitting proton-nucleus data.12 Figure 4 shows that the this success to lower energy proton scattering seems to impulse approximation generally explains the necessary require that some lessons from meson theory and Dirac strengths of Dirac phenomenology for TL ^ 300 MeV, phenomenology be taken into account. including the curious fact that the scalar potential has a positive imaginary pan that corresponds to emission rather than absorption. Optical-Potential Strengths, Meson Contributions, The relation between Dirac and Pauli AW amplitudes and the Low-Energy Problem illuminates how the large scalar ?nd vector strengths of opposite sign come about. In general, a complicated five- The first predictions of the Dirac impulse approxima- by-five matrix connects the two representations for on- tion were the strengths of scalar and vector optical shell scattering2 as discussed in Ref. 14; however, a potentials.13 Figure 4 shows the real and imaginary transparent connection arises for forward scattering optical-potential strengths based on a constant nuclear (9 = 0) in the laboratory frame. density of 0.16nucleons/fm3. The energy dependence

2m(EL + m) C B m m [lab lab ' lab '-lab (34) 1 EL- m

600 1 1 \ReV (Q) 400 ---VS^ 200 - ^ XvnS <

I I o 200 400 600 800

0 (> —s— 8 "'ImV -200 - — " . •

-400 -•-"

i 1 1 -600 200 400 600 800 1000 200 400 600 800 1000 Kinetic Energy (MeV) Fig. 4(a) and (b). (a) Strengths of vector and scalar Dirac optical potentials for central nuclear density p = 0.16/fm3 vs laboratory kinetic energy of the proton. Dashed curves show imaginary parts and solid curves show real parts of the potentials based on impulse approximation. Dash-dotted curves show results at low energy based on Brueckner-Hartree-Fock analysis (Refs. 30 and 31). Points are results of Dirac phenomenology fits to p-nucleus data. (b) Ratio of real vector strength to real scalar strength based on impulse approximation (solid line) and the results of Dirac phenomenology (points). The dashed lines show m/E. . .

November 1983 LAMPF USERS GROUP PROCEEDINGS 53 Los Alamos National Laboratory m j. 2m(EL +m) r ^.R m Fso= + = Clab +Blab ~ P EL-m }

m Uab -lab (36) EL-m

Here, EL and i>L are the laboratory energy and momen- meson exchange to the optical potential. In the represen- tum of the proton. The large scalar vector difference tation [Eq. (9)] of the Dirac amplitudes, nucleon-ex-

arises because the spin-orbit amplitude C/a£ enters these change contributions can be rewritten using the same five expressions with opposite signs and is multiplied by an Dirac forms as for direct scattering by means of a Fierz 2 energy-dependent coefficient, 2m(EL + m)/PL (~5 for transformation. However, the variable q is replaced 500-MeV protons, ~8 for 100-MeV protons). Thus the by u, the exchange channel four-momentum squared, in observed AW spin dependence fixes C^ , and this in the nucleon-exchange cases.

turn fixes the scalar vector difference. Predominantly, it is The Dirac scalar amplitude Fs, which is obtained from the nucleon-nucleon p waves that matter. For energies on-shell AW scattering, naturally embeds the o-meson

below about 300 MeV, the local impulse approximation contribution. Although Fs is fixed in terms of positive- overestimates the Dirac phenomenology in Fig. 4, and energy scattering data, it naturally behaves as an much of this difficulty has been traced to the analytic function of q2 analogous to the one-meson- pseudoscalar pion exchange, which is implicitly assumed exchange amplitude. Prediction of the optical-potential

in the representation of Eq. (9). coupling to negative-energy states is made by using Fs 2 It is instructive to see the contributions that various for off-shell q values in just the same fashion as would mesons make to the optical potential. The invariant be done for o-meson exchange. Similarly, the vector 2 amplitude F used above is related to a Feynman amplitudes Fw(q ,S), analytically extended to off-shell 2 invariant amplitude £lf by a kinematic factor, that is, q values, also contribute to the negative-energy coupling in the same fashion as the cu-meson exchange that it embeds. F= ;ll/(2ikm) (37a) It is important to note that the negative-energy couplings that occur in the Dirac optical potential or involve small four-momentum transfer, q ~ 1-2 fm~", and so the amplitudes remain near the on-shell point. An (37b) important feature of the representation used in Eq. (9) is that it is free of kinematic singularities and hence does not disrupt the analytic continuation process that under- where k is the momentum in the AW center-of-mass NN lies the success of the relativistic impulse approximation. frame and 5 is the AW system's total four-momentum NN Alternative representations of the AW amplitudes can be squared. Notice that the optical potential of Eq. (33) is of given; however, they generally do not provide desirable the form ?p in terms of the I matrix defined by Eq. (37b). analytic properties, a point that was first emphasized by For c-meson exchange, the Feynman amplitude is Goldberger, Grisaru, MacDowell, and Wong in I960.15 The pion contributions listed in Table I show that the (38) nucleon-exchange diagram gives large, nonlocal con- m\-q2 tributions to S and V that are opposite in sign. In the local approximation, the M-channel momentum transfer 2 2 where q2 is the four-momentum transfer squared. In is replaced by the on-shell relation, u = 4m s-q = 2 addition, there is also a nonlocal contribution in which 2mTL - q , where TL is the proton kinetic energy. This the two nucleons are exchanged as dictated by the Pauli approximation treats nucleon-exchange contributions as principle. Table I lists the contributions of a-, to-, and n- energy-dependent, local contributions to S and V.

54 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Table I. One meson-exchange contributions to the scalar, vector, tensor, pseudoscalar, and axial-vector Feynman amplitudes. For example, row 1 shows that the scalar AW ampb'tude receives contributions from direct o-meson graph and from a-,«-, and it-meson exchange accompanied by Pauli exchange of the two nucleons. The isoscalar

proton-nucleus optical potential omits all terms proportional to f, • T2, but this leaves a part of the one-pion contribution associated with Pauli exchange. Direct Exchange

Meson Mass

1 gl Scalar -500 -_-2 4 ml- u /rty — u 8 ml- u

gl 1 gl gl 1 gl Vector co 780 4 ml- u m$- u 8 ml- u

1 gl 1 gl Tensor 8 mi- u 16 ml- u

gl T| • T2 1 ll gl 1 gl Pseudoscalar Tt 140 (3-T,.T2) 4 m\- u ml- u 8 ml- u

1 gl 1 gl 1 gl Axial + — (3-T,-T2)

It is clearly preferable to treat the nucleon-exchange Typically the optical potential obtained using such process as a nonlocality; however, this seems to not be effective parameters is in reasonable agreement with an important issue for 500- to 800-MeV, forward-angle Dirac phenomenology in the 0- to 100-MeV region.12 proton scattering. Nucleon-exchange processes are only In recent work by Shakin and collaborators,30"32 a important at backward angles or at low energy. They more predictive approach has been used that also is explain the rapid increase in scalar and vector strengths based on pseudovector nN coupling. Starting from a seen in Fig. 4 at low energy as being due largely to the mesonic quasi potential determined by fitting AW phase pseudoscalar pion contributions of the form shifts, Celenza, Pong, and Shakin31 calculate a rel- 2 ±gl/(ml + 2mTL-q ), which can be seen in Table I ativistic nuclear-matter g matrix and show that it is when u is replaced by its on-shell value. possible to predict the low-energy optical potential and A lesson from the quantum hadrodynamics model other low-energy phenomena. The physics is much the initiated by Walecka28 and extended by Chin, Walecka, same as the Walecka mode!; however, the free Serot, and Horowitz29 is that a pseudovector nN cou- parameters are eliminated by use of the g matrix. In pling is needed to explain low-energy phenomena such as essence, the low-energy optical-potential strength is ex- nuclear saturation and single-particle spin-orbit split- plained by the first term of Eq. (32), where T° is the tings. In the Walecka model, the optical potential at low Pauli-blocked AW / matrix and where the Dirac single- energy is given by one-meson-exchange contributions particle states of the nuclear ground state are self- using effective coupling constants and masses for o and consistently determined by the same potential. Dot- (o mesons. Saturation is not predicted but rather is used dashed lines in Fig. 4 indicate the nuclear-matter results as a constraint to fix the parameters of the model. of Celenza, Pong, and Shakin in the 0- to 200-MeV region.

November 1983 LAMPF USERS GROUP PROCEEDINGS 55 Los Alamos National Laboratory The success of the free NN interaction at These potentials have been calculated in Refs. 34 and 35,

TL > 300 MeV coupled with the success of the Pauli- and they are based on AW amplitudes calculated from a blocked, pseudovector / matrix at low energy is ex- recent phase-shift solution by Arndt and Roper. In the tremely suggestive. Work is in progress to test the nuclear interior, real scalar and vector potentials are very hypothesis that these ideas, together with appropriate strong but of opposite sign. The tensor potential is smaller treatment of nonlocalities, will extend the parameter-free by a factor of 100. Contributions to the tensor potential Dirac approach from 0 to 1000 MeV!33 due to scattering of the proton's anomalous magnetic moment by the Coulomb field of the nucleus are included in Fig. 5(c), and this accounts for the slow fall off with Proton-Nucleus Scattering at Intermediate Energy increasing r. Electromagnetic- and strong-interaction contributions to the tensor potential are comparable. For finite nuclei, the Dirac potentials tend to have The solid lines in Figs. 6 and 7 present impulse- shapes similar to the nuclear density, as shown in Fig. 5. approximation results for p + 40Ca and p + 208Pb at

SCflLRR POTENTIAL VECTOR POTENTIflL 200 400 (a) (b) *"*'"^ •"*. 200

w -'

-400 -200

-400 5 10 10 R(fm) P-CC40 "49/.S MEV B.F P-C«(0 197.5 MEV e.F 5ER0T DENSITIES SEROT DENSITIES U1IH TENSOR BNO UNO.HI WITH TENSOR fUO RNO.H

TENSOR POTENTIflL

(c)

Fig. 5(a}-(c). (a) Scalar potential S(r), (b) vector potential V(r), and (c) tensor potential 2T(r) for/>-40Ca scattering at 497 MeV. Solid lines show real parts and dashed lines show imaginary parts. e\i

-I 5 10

P-CS140 1197.5 MEV S.F R(fm) SEHOT OENSITIES KITH TENSOR flND UNO.nnG.HOH.

56 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory 10*, (deg) cm.

Fig. 6(a)-(c). Dirac impulse-approximation results (solid lines) compared with data and with KMT impulse approximation (dashed line) for 497-MeV p-40Ca scattering. Calculations are from Ref. 34.

497 MeV in comparison with Los Alamos data ' and 800 MeV. The fact that the tensor potential is of the order nonrelativistic results (dashed lines). These calculations of 1% of the scalar and vector potentials, but nevertheless are based on relativistic Hartree densities ps(r) and causes significant changes to Ay and Q observables, Pv(r)—the tensor term is omitted. Numerical folding of illustrates the sensitivity of the Dirac calculations to small the AW amplitudes was performed in the same fashion as changes. It is highly nontrivial that predictions based on for careful nonrelativistic analyses. The calculations the free AW amplitudes pass so closely to the experimen- confirm the results shown in Fig. 3 in that the Dirac tal points. Attempts to describe these data using effective approach provides much improved prediction of the spin AW interactions in the nonrelativistic framework of observables. Eq. (5), with AW parameters adjusted to optimize the fit, Figures 8 and 9 show the effects of the tensor term in have been comparatively unsuccessful. the optical potential. These effects are most significant at

November 1983 LAMPF USERS GROUP PROCEEDINGS 57 Los Alamos National Laboratory I.U i

(b) I 4 1 '»* 1 i H A 1,'ft L 0.5 / V. I 11 r 1W ! rfs Ii I1 1 • V I

10 20 30 40 ecm.

Fig. 7(a)-(c). Dirac impulse-approximation results (solid lines) compared with data and with KMT impulse approximation (dashed line) for 497-MeV /?-208Pb scattering.

o o

Fig. 8. Tensor term in Dirac impulse approximation, included in dashed curves but omitted from solid curves. Results are for 497-MeV p-40Ca.

58 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory pseudoscalar coupling treated in a local approximation causes too much scalar-vector difference and thus too large pair contributions. Once this problem is remedied, the Dirac optical potential is expected to be calculable from a nucleon-nucleon quasi potential over the range 0-lOOOMeV. For the energy region above about 300 MeV, the large scalar and vector potentials of Dirac phenomenology are accurately predicted by the impulse approximation. Work by Shakin and collaborators provides complementary results at low energy based on a nuclear-matter g matrix. A basic conclusion is that relativistic spin effects cannot be neglected in nuclear physics. Although it has been known for a long time that large scalar and vector potentials were needed to explain nuclear saturation and spin-orbit splittings of bound states, never before has the connection between these potentials and the on- shell AW amplitudes been as clear. The proton-scattering data obtained at the LAMPF High-Resolution Spec- trometer have provided our clearest signal that relativistic effects of dynamical origin are essential ingredients of nuclear physics. Support of the United States Department of Energy 30 and the University of Maryland Computer Science Cen- (deg) ter for this research is gratefully acknowledged.

Fig. 9. Tensor term in Dirac impulse approximation, in- REFERENCES cluded in dashed curves but omitted from solid curves. Results are for 800-MeV />-40Ca. 1. G. W. Hoffmann, L. Ray, M. L. Barlett, R. Fergerson, J. McGiil, E. C. Milner, K. K. Seth, D. Barlow, M. Bosko, S. Iverson, M. Kaletka, A. Saha, Summary and D. Smith, Phys. Rev. Lett. 47. 1436 (1981); and G. W. Hoffman, L. Ray, M. L. Barlctt, W. R. The Dirac impulse approximation has to date provided Coker, J. McGiil, G. S. Adams, G. J. Igo. F. Irom, dramatic improvement in our ability to predict, with no A. T. M. Wang, C. A. Whitten, Jr., R. L. Boudrie, J. free parameters, spin observables in proton-nucleus F. Amann, C. Glashausser, N. M. Hintz, G. S. Kyle, elastic scattering at intermediate energies. The key ingre- and G. S. Blanpied, Phys. Rev. C 24, 541 (1981). dients of this approach are Dirac propagation and the nucleon-nucleon invariant amplitudes. 2. L. Ray. G. W. Hoffmann, M. Bariett, J. McGill, J. So far, local approximations to the AW amplitudes Amann. G. Adams, G. Pauletta, M. Gazzaiy, and have been used. The standard AW representation (in G. S. Blanpied, Phys. Rev. C 23, 828 (1981); and A. terms of Dirac scalar, vector, and so on, parts) that is free Rahbar, B. Aas, E. Bleszynski, M. Bleszynski, M. of kinematical singularities seems to naturally predict the Haji-Saeid, G. J. Igo, F. Irom, W. D. Cornelius, M. correct coupling to negative-energy states for energies Barlett, G. W7' Hoffmann, C. Glashausser, S. above 300 MeV. At low energy this coupling is subject to Nanda, and M. M. Gazzaiy, Phys. Rev. Lett. 47, an ambiguity between pseudoscalar and pseudovector 1811 (1981). rcN-coupling mechanisms, and it is evident that the

November 1983 LAMPF USERS GROUP PROCEEDINGS 59 Los Alamos National Laboratory 3. L. Ray, Phys. Rev. C 19, 1855 (1979); D. A. 10. J. Kelly, W. Bertozzi, T. N. Buti, F. W. Hersman, C. Hutcheon, J. M. Cameron, R. P. Liljestrand, P. Hyde, M. V. Hynes, B. Norum, F. N. Rad, A. D. Kitching, C. A. Miller, W. J. McDonald, D. M. Bacher, G. T. Emery, C. C. Foster, W. P. Jones, D. Sheppard, W. C. Olsen, G. C. Neilson, H. S. Sherif, W. Miller, B. L. Berman, W. G. Love, and F. D. K. McDaniels, J. R. Tinsley, L. W. Swanson, P. Petrovich, Phys. Rev. Lett. 45, 2012 (1980); and H. Schwandt, C. E. Stronach, and L. Ray, Phys. Rev. V. von Geramb, The Interaction Between Medium Lett. 47, 315 (1981); L. Ray, Th? Interaction Energy Nucleons in Nuclei—1982, H. O. Meyer, Between Medium Energy Nucleons in Ed., AIP Conf. Proc. No. 97 (AIP Press, New York, Nuclei—1982, H. O. Meyer, Ed., AIP Conf. Proc. 1983), p. 149. No. 97 (AIP Press, New York, 1983), p. 121; and S. J. Wallace, in Advances in Nuclear Physics, J. W. 11. L. G. Arnold, B. C. Clark, R. L. Mercer, and P. Negele and E. Vogt, Eds. (Plenum, New York, Schwandt, Phys. Rev. C 23, 1949 (1981), and 1981), Vol. 12, p. 135. references therein.

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7. R. J. Glnuber and P. Osland, Phys. Lett. 84B, 157 18. L. Ray, invited talk presented at the University of (1979). Alberta/TRIUMF Workshop on Studying Nuclei with Medium Energy Protons, Edmonton, Alberta, 8. A. K. Kerman, H. McManus, and R. Thaler, Ann. 1983. Phys. (NY) 8, 551 (1959). 19. N. F. Mott and H. S. W. Massey, Theory of Atomic 9. R. J. Glauber, in Lectures in Theoretical Physics, Collisions, Third Ed. (Oxford Press, Oxford, 1965), W. E. Brittin and L. G. Dunham, Eds. (Interscience, p. 226. New York, 1959), Vol. 1, p. 315.

60 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory 20. S. J. Wallace and J. L. Friar, University of 30. M. R. Anastasio, L. S. Celenza, and C. M. Shakin, Maryland technical report ORO 5126-196, sub- Phys. Rev. Lett. 45, 2096 (1980); and L. S. Celenza, mitted for publication November 1983. B. Goulard, and C. M. Shakin, Phys. Rev. D 24, 912 (1981). 21. J. D.Jackson, Classical Electrodynamics, Third Ed. (Wiley, New York, 1983), p. 364. 31. L. S. Celenza, W. S. Pong, and C. M. Shakin, Phys. Rev. Lett. 47, 156 (1981); and Phys. Rev. C 25, 22. E. E. Salpeter and H. Bethe, Phys. Rev. 84, 1232 3115 (1982). (1951). 32. M. R. Anastasio, L. S. Celenza, W. S. Pong, and C. 23. R. Blankenbecler and R. L. Sugar, Phys. Rev. 142, M. Shakin, to be published in Phys. Rep. 1051 (1966). 33. J. A. Tjon, M. J. Iqbal, and S. J. Wallace, in 24. F. Gross, Phys. Rev. 186, 1448 (1969); and Phys. preparation. Rev. C 26, 2203 (1982). 34. B. C. Clark, S. Hama, R. L. Mercer, L. Ray, and B. 25. K. Holinde, Phys. Rep. 68C, 122 (1981); and J. D. Serot, Phys. Rev. Lett. 50, 1644 (1983); L. D. Fleischer and J. A. Tjon, Phys. Rev. D 21, 87 Miller, Phys. Rev. Lett. 51, 18O7(C) (1983); and B. (1980). C. Clark, S. Hama, J. A. McNeil, R. L. Mercer, L. Ray, G. W. Hoffmann, B. D. Serot, J. R. Shepard, 26. S. J. Wallace and J. A. McNeil, in preparation. and S. J. Wallace, Phys. Rev. Lett. 51, 1809(C) (1983). 27. M. L. Goldberger and K. M. Watson, Collision Theory (Wiley, New York, 1964). 35. B. C. Clark, S. Hama, R. L. Mercer, L. Ray, G. W. Hoffmann, and B. D. Serot, Phys. Rev. C 28, 1421 28. J. D. Walecka, Ann. Phys. (NY) 83,491 (1974); and (1983). Phys. Lett. 79B, 10 (1978). 36. M. L. Barlett, L. Ray, and G. W. Hoffmann, 29. S. A. Chin, Ann. Phys. (NY) 108, 301 (1977); B. D. University of Texas preprint (1983). Serot and J. D. Walecka, Phys. Lett. 87B, 172 (1979); B. D. Serot, Phys. Lett. 86B, 146 (1979); C. J. Horowitz and J. D. Walecka, Nucl. Phys. A 364, 429 (1981); and T. Matsui and B. D. Serot, Ann. Phys. (NY) 144, 107(1982).

November 1983 LAMPF USERS GROUP PROCEEDINGS 61 Los Alamos National Laboratory MUON-NEUTRINO PHYSICS BEFORE THE PSR

G. J. Stephenson, Jr. Los Alamos National Laboratory

As you all know, there is an active and productive neutrino program at LAMPF that views the Line A beam stop as a neutrino source. Experiment 31 established important limits on the form of weak interactions and early limits on oscillation phenomena, Exp. 225 is performing a crucial and fundamental measurement of

charge-current/neutral-current interference in vc-e scattering, and Exp. 645 will provide unique information on

possible vu —»• ve oscillations. The beam-stop source

produces predominantly ve, vu, and vu from the decays of K+ and u+ at rest, so the energy available in any of the neutrino species is insufficient to produce muons. These

experiments have concentrated on ve and ve measurements, discussed elsewhere in these proceedings. I concentrate here on the Laboratory's efforts to provide a

source of vu from n* decay in flight, which will produce

vu's with sufficient energy to produce u~, thereby opening up new experimental possibilities. As many of you also know, the Laboratory made a proposal to the USDOE for a major neutrino facility that would be fed by the Proton Storage Ring (PSR), which is currently being built on Line D. This coupling to the PSR was driven largely by the conclusions of the LAMPF Program Options Workshop. That group was motivated by two features, both related to the 270-ns- pulse structure of the PSR. The first was the suppression of cosmic-ray background because of the suppressed duty factor, and the second was the possibility of separating vu and vs in time. The workshop expressed great enthusiasm for the physics to be done with such a low-energy intense neutrino source. Gerard J. Stephenson, Jr. The proposal was reviewed by the Nuclear Science Advisory Committee and, following their advice, by a distinguished panel of neutrino experts from both the Nevertheless, the physics imperatives remain. With high- and low-energy nuclear physics communities. In that in mind, we have turned our immediate attention to the judgment of this panel, the physics to be done is the physics that can be done with the present LAMPF exciting and important and should be pursued in this beam. As you shall see, this is primarily vu physics from country. They had, however, technical reservations that in-flight pion decay. The rest of this paper is devoted to cannot adequately be addressed by the Laboratory until the vu physics that we believe can be done before the the PSR begins operation at large current. This is not PSR becomes operational for a neutrino source. likely until 1986; hence that full facility proposal is now The first steps of such an effort are already well under on hold. way. Experiment 764 is designed to use an existing

62 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory detector consisting of 44001 of liquid scintillator sur- close to threshold, and calculations with different models rounded by two active anticoincidence shields. As this for the final nuclear states give differences in total cross detector was originally designed to withstand severe sections of up to factors of 4 either way from the values elements, it will be adequately housed in a simple originally used to size detectors for various neutrino concrete block structure. The experiment also calls for a experiments. The first data will be from carbon; subse- neutrino flux produced by 20 uA of LAMPF beam on a quent measurements will obtain aluminum cross sec- bare target. "Bare target" here means a pion-production tions. In addition, the detector is sensitive to high-energy

target tha allows pions to escape into a decay volume electrons so that the process iyu —*• ve),

but that has ho pion-focusing device. To provide that (yc + A —*• e~ + X) can be observed. For a run next beam and target, a small portion of the facility proposal summer with 20 uA and a bare target, a limit of 10"3 on

is being implemented. The target station is located at the the probability of vu —*• ve oscillations around Ey of site specified in the proposal, and the by-pass beam line 150 MeV should be achieved.

(called Line E, as indicated in Fig. 1) is being installed. There are two developments that make further vu The primary aim of this experiment is to measure the experiments before the PSR more attractive. The first is

charge-current reactions (vH + A —> u" + X) at the neu- the success of Exp. 225 in suppressing cosmic-ray back- trino energies available at LAMPF. The energies are grounds with active anticoincidence shields. This fact,

NEUTRINO FACILITY BEAM TRANSPORT

Fig. 1. Artist's conception of Line E in conjunction with Line D, the Weapons Neutron Research (WNR) facility, and the Proton Storage Ring (PSR). LineE magnets are cross hatched. In the actual configuration, to avoid obstacles in the tunnel, Line E is above and to the west of Line D.

November 1983 LAMPF USERS GROUP PROCEEDINGS 63 Los Alamos National Laboratory coupled with the lower background at higher energy, and use the rest of Line A as a decay volume. The shows that it is possible to work with the LAMPF beam advantage here is the use of about 1 rnA of current, structure in very large detectors. The second develop- slightly degraded in energy. Of course the existing ment is the recognition by the Exps. 638/764 collabora- programs in the beam-stop area will have to be sup- tion that the LAMPF microstructure (0.5-ns pulses, 5 ns ported, either by constructing new facilities or by time apart) can provide additional information on the neutrino sharing with the neutrino mode. Then the neutrino energy. program would not take beam away from Area A, For this discussion, I assume the existence of a running time would be matched to that area, and the focusing device with the characteristics used in our beam stop would be optimized for neutrino physics. facility proposal. I return to the question of a focusing An additional advantage to the Line A proposal is the device, which is nontrivial, below, but the Monte Carlo ease with which it could be incorporated into several of calculations I show you are based on this assumption. the LAMPF II scenarios now under discussion. These Basically, the idea is that there is a correlation between options will be discussed intensively over the next few neutrino arrival time at the detector and neutrino energy. months, and extensive user input is sorely needed. This is obviously a time-of-flight technique, but it is Either scenario will require a strong effort to design based on the velocity of the parent pion, not the neutrino. and prototype a pion-focusing device. The facility The argument and calculations that I present here are proposal contemplated a pulsed horn similar to those from Tom Dombeck. used at high-energy facilities. For a pulse duration of If the total distance from the source to a particular 270 ns, pulsed power techniques are straightforward, but detector plane is L, the average distance toward the 750 us is another matter. While we are pursuing such detector traveled by the pion is £, and the velocity of the horn designs, we are also studying the possibility of using pion is Pc, then the time from production to detection is a dc device. Such a magnet has the disadvantage that pole pieces and coils cut out azimuthal solid angle, but has the advantage that the fields can be shaped for our low-energy pion spectrum. Preliminary design studies t_ I ^ L-t _ L| tl 1 [3c c c c \ p carried out last summer indicate that we can build such a device with the same gain as we expected from a horn. A small-scale prorotype is being constructed and will be used to verify magnetic-field calculations. We should The use of this is complicated by the factors of the have clear results by next summer. distributions of the energy of pions decaying at a particular I and the integral over I. To demonstrate this fact, Monte Carlo results are shown in Fig. 2. Clearly, then, the Laboratory is investigating the TIME SEPARATION OF ENERGY COMPONENTS IN THE NEUTRINO SPECTRUM possibility of providing a high-intensity source that uses 300 LAMPF beam and has pion focusing both for intensity TIME-INTEGRATED and for sign selection. Two possibilities are evident: (1) SPECTRUM to use Line E, or (2) to use the beam-stop area of Line A.

We will run Exp. 764 on Line E next summer and will 100 200 300 learn about its characteristics then. One may con- NEUTRINO ENERGY

64 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory In conclusion, I want to acknowledge the very strong months. Hence, we n.ed still more of your support and support that we have received from the user community, advice, which I know we can count on. especially from the collaborations involved in Exps. 31, 225, 638, 645, and 764. Without their help and en- couragement this program would have floundered. As Acknowledgement you see, it is still not up and running and several major decisions will have to be made over the next many This work was supported by the United States Depart- ment of Energy.

November 1963 LAMPF USERS GROUP PROCEEDINGS 65 Los Alamos National Laboratory ENERGY AND ANGULAR DEPENDENCE OF THE TENSOR

POLARIZATION t20 IN nd ELASTIC SCATTERING

W. Griiebler ETH, Switzerland

Introduction

For many years the study of nd elastic scattering has been the subject of intense theoretical calculations. These investigations are important for two fundamental processes: (1) the true absorption of a pion by two nucleons, and (2) the interaction of the two nucleons. In the domain of the elementary TV* resonances, particular interest is directed to the coupled nNN-N*N problem in order to investigate the N*N interaction. In the pion energy region where the (3,3) resonance dominates, only weak signals beyond the NA interaction are expected because the A resonance is rather broad (100-200 MeV). In recent years nd scattering has gained additional interest in the context of quark dynamics. Beyond the simplest q} nucleon and qq meson configurations, numer- ous authors have speculated on the existence of long- lived multiquark systems. One of the promising candidates is the six-quark system with nonconventional colored subclusters, which are different from nucleons and mesons and therefore are extremely interesting to explore in order to investigate the nature of the color degrees of freedom. This consideration leads to the possible existence of dibaryon resonances, which have been suggested in the analysis of Willi Griiebler nucleon-nucleon scattering, the photodisintegration of deuterons, and the polarization observables of nd Abstract scattering.3'5 From bag model calculations some dibaryon resonances are expected to have narrow widths, a feature that could be used as a signature for The tensor polarization t20 of the recoil deuterons from n V elastic scattering has been measured between this type of resonance.

Tn - 110 and 150 MeV. The angular distribution in the It is well known that spin-averaged observables like backward hemisphere shows large oscillations near differential and total cross sections have a reduced 134 MeV; a considerable flattening is observed at the sensitivity to resonance effects for small channel cou- lower and higher energies. An excitation curve of ?20 at plings. Whereas the vector polarization //,, stems always

0c m =150° shows a clear peak near the mass 2.14 GeV from the interference of at least two partial waves, the with a structure about 10 MeV wide; a phase-shift tensor polarization components can occur from a single analysis of all available n+d scattering data in this energy resonant matrix element, increasing the sensitivity of the range has been performed. The strong energy and observable to resonances considerably. The energy de- angular dependence is believed to manifest evidence for pendence of this spin observable is the most important near conventional dynamics. information for the evidence of individual resonances.

66 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory For these reasons, we have measured the tensor polariza- position in Fig. 2. The thickness of the 3He target and + tion t20 of the recoiling deuterons in n d elastic scattering hence the energy spread of the emitted protons can be in relatively smail energy steps over the energy range seen clearly by the length of the extended ridge in the between approximately 110 and 150 MeV. energy axis. The low-energy end of this peak is determined by the exceptionally high Q value of the 3He(^)4He reaction (Q= 18.4 MeV) and the trans- Experimental Arrangement mission mode used in the polarimeter. Because of the time structure of the n+ beam (pulse The measurements were carried out using the high- width 2 ns, repetition rate 50 MHz, corresponding to

intensity 71EI pion channel of the meson facility at the 20 ns), particles induced by pions in and near the LD2 Swiss Institute of Nuclear Research (SIN). A schematic and 3He targets, which are accidentally coincident with of the experimental arrangement is shown in Fig. 1. The deuterons, give rise to the two characteristic peaks in recoiling deuterons from the LD2 target are focused by Fig. 2 at approximately 3 and 23 ns. In general these quadrupole magnets in the deuteron polarimeter, which particles have a much lower energy-loss signal than the is based on the 3He(rf,p)4He reaction. The time of flight /, protons from the polarimeter reaction. A few protons between two scintillator detectors placed in front of the from the 2H(jr,it')p.« reaction can pass all preceding polarimeter, as well as corresponding energy windows in filters. They are faster than the deuterons and therefore the electronics, allows a clean identification of the appear on the right-hand side in the time spectrum at deuterons incident on the polarimeter. The size and the about 10 ns. It is clearly seen from Fig. 2 that the region position of these two detectors limit the deuterons around the desired events is practically free of back- accepted into the 3He cell. ground.

A second flight path with the time t2 between the first The data obtained with the above-described setup deuteron scintillator and the proton scintillator detectors have been checked by a two-arm arrangement, using the after the polarimeter, coupled with the energy measure- n+d coincidence technique in addition to previous filters. ment of the proton, gives enough suppression of un- This modification is also shown in Fig. 1 (pion telescope wanted events to allow clear recognition of the real with detectors H and G). protons from the 3He(d,p)*He reaction. The events that approximately fulfill the required time and energy conditions are stored event by event in a Deuteron Polarimeter PDP-11 computer. A typical example of such a plot is shown in Fig. 2. The finai data analysis is made off line The high-efficiency polarimeter is based on the reac- by software windows inspecting the number of counts as tion 'He^p^He. This reaction has been studied ex- a function of the time of flight t2 and the energy of the tensively in our laboratory in the energy range between 0 protons in the scintillator telescope of the polarimeter. and 40 MeV6 and calibrated absolutely with the well- 7 The time of flight t2 of the particles for a real event is known do. elastic scattering. The chosen polarimeter about 15 ns. This corresponds to the large peak at this reaction has the advantage that the tensor analyzing

X Q R ABC

H •' er , 'ABSORBER X X QUADRUPOLE: MAGNETS

Fig. 1.

Experimental arrangement for the measurement of t20 in nd scattering.

November 1983 LAMPF USERS GROUP PROCEEDINGS 67 Los Alamos National Laboratory 0

Fig. 2. Three-dimensional diagram of the particles detected in the proton telescope of the deuteron polarimeter.

power Tl0 is large and varies smoothly over a large where r0 is the ratio for unpolarized beam, which was deuteron energy range. In addition, it has an excep- found to be typically 0.7 • 1(T4. tionally high Q value so that the emitted protons are The calibration of the polarimeter has been performed easily distinguished from the protons of other reactions. with the polarized deuteron beam from the injector The 3He was contained in a cylindrical gas cell 3 cm in cyclotron at SIN. This calibration has been made over a diameter and 3 cm long. It had a pressure of 16 bars at a large energy range and has been repeated several times, temperature of 10 K. The emitted protons have been always giving consistent results. The sensitivity of r and measured in a forward cone of a half angle of 13° by a r20 to the position and angle of the incident beam was scintillator telescope ABC. The veto counter C rejects investigated and found to be quite uncritical for the small particles that do not meet the required energy conditions. target size and well-defined proton detector geometry. The polarimeter setup is shown in Fig. 3. The recoil deuterons in the n+d measurement have an The polarimeter works in a transmission mode—that appreciable energy spread. The energy spectrum of these is, the deuterons leave the target gas with an energy deuterons entering the polarimeter was measured by larger than about 6 MeV and are stopped in an absorber means of range curves, taken using absorbers between plate, in this way avoiding the steep slope in the detectors Q and R. This enabled correct averages of T20 6 excitation curve of the analyzing power below 5 MeV and r0 to be made over the appropriate energy range and the sharp resonance at 430 keV. The tensor using the point-by-point calibration data. polarization t20 of the incident deuterons is determined In the nd experiment the recoil deuterons are easily by the ratio r of the number of protons Np produced in identified at the entrance of the polarimeter by the energy J 4 the He(3,p) He reaction to the number of incident windows in the detectors Q and R and the flight time deuterons Nd. The tensor analyzing power ?20 is then between those detectors. A critical point could arise from given by the relation a loss of deuterons in the transmission from detector R through the 3He target cell, as can be seen from Eq. (1). This problem has been studied experimentally as well as by the computer ray-tracing program TURTLE.

68 LAMPF USERS GROUP PROCEEDINGS November 7983 Los Alamos National Laboratory 50 100 DETECTOR S

SCALE (mm)

3He CELL

DETECTOR ABC

ALUMINUM ABSORBERS^— -^

BEAM

\!SS APERTURE

HEAT SHIELD EXIT WINDOW

ALUMINUM ABSORBER

PHOTOTUBE DETECTOR R

Fig. 3. Cross section of the deuteron polarimeter.

For the transmission measurement, the deuteron ab- (1) optical ion loss by the divergence of the deuteron sorber that was after the 3He cell was removed and then beam, the ratio of the deuteron counts between the detectors S (2) loss of deuterons by scattering in the target cell and R was determined. The results of this investigation at windows and the 'He gas, and 134-MeV pion energy as a function of the scattering (3) loss of stopped deuterons in the exit window from angle 9d are shown in Fig. 4. The constant loss of 19% the low-energy tail of the deuteron energy distribu- stems from three different sources: tion.

November 1983 LAMPF USERS GROUP PROCEEDINGS 69 Los Alamos National Laboratory 1.0 1 1 1 1 selection of the correct events and the practical absence of background. Tests performed for this aim are

(1) warming up the LD2 target to 40 K (a change of density by a factor of 60) or emptying the target — •>• — completely,

(2) replacing the LD2 target with an LH2 target,

/ (3) stopping the deuterons by an appropriate absorber between detectors Q and R, (4) stopping the protons from the 3He(

angle 9d for Tn= 134MeV. protons and the accidental events [compare with the peaks in the three-dimensional plot (Fig. 2)] as a function of the kinematical conditions cor- Thp computer simulation of the deuteron trajectories responding to the different scattering angles. indicates a 12% loss from the ion optical divergence of In all these tests the spectra behave as expected. the beam. However, only a fraction of these deuterons are lost before they can induce the 3He(rf,/j)4He reaction (see Fig. 3). Results The same remark applies to the scattered deuterons in the target cell. The stopped deuterons in the exit windows Measurements of angular distributions have been

are a fictitious loss because all these deuterons pass the carried out at pion energies of Tn= 117, 125, 134, 142, 3He volume. These considerations show that the effective and 151 MeV. Samples of the angular dependence are

remaining loss is approximately 10%, which was taken shown in Fig. 5. The tensor polarization t20 is plotted in into account in the data analysis. However, this problem the laboratory system vs the angle 8C ra . The upper scales

introduces in the determination of ?20 an uncertainty in indicate the laboratory scattering angle between the the absolute value that could even change the sign of the incident pion beam and the direction of the recoiling polarization if the term deuterons. The open circles in Fig. 5 indicate the results with the i t vo-arm technique. Moreover, the angular distribution at 117 MeV was remeasured with a better focused beam (main user mode instead of the parasitic mode of the SIN in Eq. (1) were nearly unity. Allowing a variation of the jrEl channel). The new main user mode measurements at magnetic field in the quadrupole magnet of ± 1.5% from 117 and 151 MeV without n+d coincidence are indicated the ideal value induces a variation in the deuteron by triangles. transmission of +3%. The effective transmission change From Fig. 5 it is clearly seen that the angular and is even lower. The experimental magnt i netting has been energy dependence previously observed is confirmed in checked against the theoretical setting calculated from every respect. The data at Tn= 151 MeV show a similar the nd laboratory kinematics. behavior to those at 117 MeV. Whereas at 134 MeV a One of the most difficult problems in the nd experi- strong and fast oscillatory behavior is observed, the data ment is the low rate of real events in the proton telescope at lower and higher energies show a strong flattening of in the presence of a high background in the single the oscillations, thus indicating a rapid energy de- detectors. Many tests have been performed to assure pendence.

70 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory >r ctou 75° 60° 45° 50° 15° 0° 0.4' i " "

0.2 T,.N7 MeV / 0.2 t XI *i O i J *S. i i 0 "J* 0 t - \^ -0.2 -0.2 0° 30° 60° 90° 120° 150° 180°

a lab

9 75° 60° 45° 30° 15° 0° OR °° , n a

Fig. 5.

Angular distribution of t2f at T, = 117, 134, and 151 MeV. The open circles are daia taken with the two-arm arrangement. The triangles at 117 and 151 MeV represent data measured in the main user mode. At 134 MeV all data are obtained in the main user mode. The curves are fits from a phase- 0° 30° 60° 90° 120° 150° 180 shift analysis.

90° 75° 60° 45° 30° 15° 0° 0.4 0.4 0.2 TTT= 151 MeV 4 - 0.2

0 7^ ' r/ -•-' \ / -0.2 H-0i.2 \\ / -0.4 0.4 \ I -0.6 \ / -0.6 -0.8 o.e 30° 60° 90° 120° 150° 180°

The results for a fixed deuteron recoil angle A tensor polarization measurement of t20 also has 8 gjab_ ^ corresponding to 6cm = 150°, are shown in been carried out at LAMPF by Holt et al. The results at

Fig. 6. The upper scale indicates the mass of the system. 142 MeV and 0C m = 180° agree with the data presented It should be remarked that the peak value of t2g occurs here. The data at smaller angles measured by a different near the mass 2.14 GeV where pp scattering has already setup have consistently negative /20 values. Un- 1 independently suggested a 'D2 dibaryon resonance. The fortunately, no data have been taken in the most energy dependence in the measured region suggests a interesting angular region where the strong structures in structure approximately 10 MeV wide, much smaller our data are observed. than that indicated by the resonance circle in the Argand The data at the smallest scattering angle 0d=18°, plot of pp scattering. corresponding to 0c.m. = 144°, are shown in Fig. 7 in

November 1983 LAMPF USERS GROUP PROCEEDINGS 71 Los Alamos National Laboratory 2.15 2.16 GeV 2.12 2.13 2.14 2.15 2.16 GeV

J-0.2 -

110 120 130 140 150 160 MeV

110 120 130 140 150 160 MeV Fig. 6. b Excitation function of *2'g at 0,. m = 150° Fig. 7.

Comparison of data from Ref. 8 at 9cm. = 144° with the present data at 140° as a function of comparison with the SIN data at 140°. The most energy. pronounced difference between these two data sets is the sign of the polarization. In clear distinction to vector-polarization measure- It is clear from this limited data set that one cannot

ments, the sign of t20 is not determined by a left-right expect a unique phase-shift solution, but the aim of this asymmetry but by absolute measurements of polarized analysis is to investigate the possibility to fit all three and unpolarized cross sections—that is, by the absolute different observables at one energy by the same set of measurements of counting rates in two different experi- phase shifts and to find the most sensitive phases that are

ments, namely the calibration of the polarimeter and the responsible for the fast change of t2a in angle and energy. nd experiment. For this reason the determination of the For this goal, single energy fits have been carried out sign of the polarization with the present polarimeter with a general spin-1, spin-0 phase-shift code named arrangements is a difficult experimental task; therefore, ONEZERO, which takes into account all degrees of at present the sign difference should not be over- freedom such as splitting and mixing of phase shifts that estimated. On the other hand, both data sets show a may occur in strong interactions. These parameters may good structural agreement in the energy dependence be complex, and the number of partial waves is not when compared at similar angles. limited by the method of programming. Analyses have been made at 117, 134, and 151 MeV. Cross-section data at these energies have been inter- Analysis polated from Ref. 10. Since at the time the analysis was performed the vector-analyzing power measurements The observation of the remarkable structure as a existed only at 142 MeV3 in our energy region, these function of angle and energy has stimulated a phase-shift values have been used for all energies. This somewhat analysis of the experimental n+rf data in this energy artificial restriction is reasonable because this observable range. There are, in addition to the present tensor is quite insensitive, at least at the present level of polarization results, differential cross-section data be- accuracy. The orbit angular momentum was restricted to tween 116- and 180-MeV pion energy and the vector- I < 5 and the mixing between channels with I =J ± 1 3 analyzing power /Tj, at Tn = 142 MeV by Bolger et al.

72 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory was neglected. The resulting fits are shown in Fig. 5 by The polarizations depend on the Af-matrix elements the dashed, solid, and dash-dotted curves. through the relations The corresponding fits to the cross-section data and the vector-analyzing power are presented in Fig. 8 with = Tr(MM+ the same signatures as in Fig. 5. In the search for the best

fits the same starting values of the phase shift have been tkq being the spherical tensor operators. The /kq reach used at all energies. It is interesting to notice that their theoretical maximum values if the matrix elements satisfactory fits to all experimental data have been fulfill certain conditions. For the theoretical value obtained, thus demonstrating the consistency of the data = 1/^2, the conditions for the M matrix are

set analyzed. The fitted curves of iTn at 134 and M00 = Af10 = 0. This means that in the M matrix all 151 MeV show in the forward angular region a negative elements in the second line and the second column dip as has been observed experimentally for this compo- disappear. As a consequence, the observables nent at higher energy, but the minimum is shifted to itu = /2] = 0. Since the contribution of f22 to the value of b smaller angles in the energy range here under investiga- /2{j obtained by the necessary rotation of the coordinate tion. It is most remarkable that the cross section and vector-analyzing power fits, in spite of the strong oscillation in the t20 tensor components, show only very moderate structures, which are well within the experimental uncertainties of these data. This observation shows that in this case a much higher accuracy in the experimental data of iTn is required for the investigation of resonance effects. The oscillations of ti0 at 134 MeV induce a fast increase of the 3P, phase shift by about 20° between 117 and 151 MeV. Relatively large absorption is observed in all channels. The present phase-shift analysis favors a 1+ state. However, this result has to be considered with care since 30° 60° 90° 120° 150° 180° the parameter set found is not unique. Therefore no final conclusion for the assignment of resonance parameters can be made. For this purpose, data extending the present angular and energy range as well as complementary polarization components are required. A convenient way to describe the elastic scattering of projectiles with spin is the helicity formalism of Jacob and Wick." A three-by-three M matrix describes the scattering of spin-0 particles by a spin-l target. The scattering amplitudes Mv,v with the z projection v of the channel spin 5 are functions of the phase shifts. Parity conservation and time-reversal invariance reduce the number of independent-scattering amplitudes to four. The M matrix therefore can be written in a cm. helicity frame as Fig. 8. Phase-shift fits of the differential cross sections o Mu M lo and the vector-analyzing power iTu at 117 MeV M(6)= Moo Mio (broken curves), 134 MeV (full curves), and 151 MeV (chain curves). The data are from Refs. 3 -M, M,, n and 9.

November 1983 LAMPF USERS GROUP PROCEEDINGS 73 Los Alamos National Laboratory system is small, we conclude that the large values of f j;b

observed at 134MeVat6cm. = 150° (andpossibly 120°) are a strong indication that the stated conditions on the M matrix are almost fulfilled. The measurements by Bolger et al.3 shown in Fig. 8 are compatible with this requirement. The most recent result measured by the same group12 with much higher

accuracy is itn (150°) = 0.078 ± 0.020. Since the t20 does not quite reach the maximum value, the data are in the expected agreement.

400 Tensor-Analyzing Power t20 at 180°

The amplitude of the single-scattering process can be Fig. 9. described by the sum of a non-spin-flip part/and a spin- Comparison of t20 (180°) with single- and multiple- flip amplitude g. At a scattering angle 180° (0d = 0°), the scattering calculations (Ref. 13). The dot and bars spin-flip amplitude g vanishes and the scattering process are SIN results; the open circle, from Ref. 8. becomes particularly simple. The tensor polarization t2a

is then given by deuteron properties alone and t20 is a measure of the ratio G2/Go of the quadrupole (G2) to the Improvements in Future Measurements 13 monopole (Go) form factor of the deuteron. At 180° one expects t20 to fall and rise with a monotonic increase The conflict between the Argonne and the Zurich data in G2/Go. calls for a new method of measuring tensor polarization, 13 The /2O(18O°) has been calculated for single and in which the absolute calibration of the polarimeter no multiple scattering (results are shown in Fig. 9). In the longer depends strictly on an auxiliary experiment with a energy region around 140 MeV the contribution of the deuteron beam with different energetical and ion optical multiple-scattering effects is relatively small. Ex- properties. This conception is being approached pres- perimental results in this energy region are also plotted in ently in our laboratory, where we are designing a this diagram. There exist two real data points: one at polarimeter that depends on the 3He(rf,/>)4He reaction but 134 MeV from our group, and one at 142 MeV (circle) that also uses a telescope at a reaction angle of 0° and

from Ref. 8. The other values (bars) are extrapolations detectors at two other reaction angles 9(. in the left and from the measured angular distributions of which the right, up and down positions. Since the tensor-analyzing

largest angle is 170 or 175°. This extrapolation is safe, power /20 does not depend on the azimuthal angle <)>, ring

since t20 must have a horizontal tangent at 180°; detectors at these scattering angles 9; would be sufficient. therefore this value cannot be much different from Besides the technical problem of building such ring neighboring angular values. The general slope of the detectors, the splitting of the rings in four single detectors experimental results is very similar to the slope of the is an advantage because such an arrangement allows calculated curve, although the experiment suggests a simultaneously the measurement of other polarization

weak oscillation in the energy region of 140 MeV. components such as the vector polarization itn and, in

However, the experimental error bars are too large for addition to t20, the tensor components t2l and f22 this observation to be significant. Considerably more (compare with Refs. 14-16). precise measurements of ?2O(18O°) are needed. These features can be best understood when re- Whereas the slope of the experimental results is in membering the polarization measurements carried out good agreement with the multiple-scattering calculation, with accelerated polarized beams from a polarized ion the absolute values are too small. It is well known from source. Here, spin flipping or polarization sign-switching the three-body calculations, however, that true pion methods are used, where the sign of the polarization is absorption changes the values /2O(18O°) considerably. reversed and the absolute polarization value is constant. On the other hand, the problem of the absolute calibra- Then the geometrical effects in the experiments are tion of the deuteron polarimeter arises here again. canceled out.

74 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Technically we have no means to use the same Acknowledgments technique with polarized particles from a nuclear reaction. In this case, however, the basic method can be The author is indebted to M. P. Locher, W. R. Gibbs, replaced by using an analyzing reaction where the and A. S. Rinat for helpful discussions concerning the analyzing po«"er at two different angles provides the theoretical aspect of the present problem. For useful reversed sign. Nature is not so kind as to please us with information on experimental problems, discussions with the strict requirement of sign change and constant R. J. Holt, E. J. Stephenson, and E. Ungricht are absolute analyzing powers. Basically, the cancellation of gratefully acknowledged. I also thank J. Ulbricht as well geometrical effects also can be obtained by analyzing as the other members of the ETH group for assistance in powers at Q., which have a large difference in the preparing this manuscript. analyzing powers—that is, a large value at one angle and a vanishing value at the other, corresponding to a REFERENCES measurement using the switching between polarized and unpolarized beam. 1. A. Yokosawa, Phys. Rep. 64, 47 (1980). It is clear that in practice the design of such a polarimeter is a compromise between the different fea- 2. K. Ikeda et al., Phys. Rev. Lett. 42, 1321 (1979). tures a particular analyzing reaction can offer. Certainly this approach to the problem of the tensor polarization 3. J. Bolger et al., Phys. Rev. Lett. 48, 1667 (1982). measurement in nd scattering has great advantages and should be used in future experiments. It will resolve the 4. J. Ulbricht et al.. Phys. Rev. Lett. 48, 311 (1982). problem of the absolute calibration of t20 and will help solve the intriguing problem of determining the existence 5. W. Griiebler et al., Phys. Rev. Lett. 49, 444 (1982). of dibaryon resonances. 6. W. Griiebler et al., Phys. Rev. C 22, 2243 (1980).

Concluding Remarks 7. W. Gruebler et a!., Nucl Phys. A 334, 365 (1980).

The observed behavior of the tensor polarization t20 as 8. J. Holt et al., Phys. Rev. Lett. 47,472 (1981); and E. a function of angle and energy is quite unexpected. The Ungricht et al., preprint submitted to Phys. Rev. fast energy variation of f20 is not compatible with the Lett. known widths of the A resonance, unless one assumes a fine structure of this resonance. Comparison with con- 9. B. Jenny et al., Nucl. Phys. A 397, 61 (1983). ventional theoretical calculations shows systematic differences, providing strong evidence for new and unex- 10. K. Gabathuler et al., Nucl. Phys. A 350,253 (1980). plained dynamical effects. A phase-shift analysis shows that the present available 11. M. Jacob and G. C. Wick, Ann. Phys. (NY) 7, 404 different kinds of observables are compatible, and (1959). furthermore, that near maximum values of the tensor polarization t20 with the nearly vanishing vector polariza- 12. E. L. Mathie et al., submitted to Phys. Rev. C. tion itu are in agreement with the data. All these observations suggest a narrow dibaryon resonance near 13. W. R. Gibbs, preprint of Los Alamos National the mass 2.14 MeV. For a final proof of the existence of a Laboratory document LA-UR-83-245 (1983). resonance and an assignment of resonance parameters, further experimental results are needed. Data extending 14. G. G. Ohlsen, Rep. Prog. Phys. 35, 717 (1972). the present angular and energy range and further polarization components may be required for this goal. 15. W. Gruebler et al., Nucl. Instrum. Methods 203, 235 (1982).

16. F. Sperisen, W. Gruebler, and V. Ko'nig, Nucl. Instrum. Methods 204, 491 (1983).

November 1983 LAMPF USERS GROUP PROCEEDINGS 75 Los Alamos National Laboratory TENSOR POLARIZATION IN PION-DEUTERON ELASTIC SCATTERING

R. J. Holt Argonne National Laboratory

Abstract

The angular dependence of the tensor polarization b /2'jj of recoiling deuterons in nd elastic scattering was measured as a function of incident pion energy in the range 134-256 MeV. No evidence was found for rapid b energy or angular dependences in /2'jJ . The results agree most favorably with theoretical calculations in which the

Pn nN amplitude has been removed altogether. This agreement is consistent with a small effect of pion absorption on the elastic channel.

Introduction

During the past few years interest in the pion-deuteron system has been spurred by questions regarding the existence of dibaryon resonances, true pion absorption in nuclei, and the quadrupole form factor of the deuteron. Another more recent development involves the effect of a quark bag model on the rcAWand nNA components that enter the theoretical models. Presently, the theoretical calculations of the nd system have achieved a high level of sophistication. These calculations are typically three body in nature and include both the absorptive channel nd—*NN and pion scattering. The results of the latest theoretical calculations are summarized in Fig. 1. Here, the calculations of Blankleider and Afnan1 (Flinders), Betz and Lee2 (Argonne), Fayard et al. (Lyon). and Rinat and Starkand4 (Weizmann) are compared with measurements cf the differential cross section5'6 and the vector- analyzing power7 ;T,, for nd elastic scattering. The results shown here are for three pion energies,

7"T = 142. 180. and 256 MeV. which represent the A- resonance region as well as the energy region where Roy Holt dibaryon-resonance effects might be present. Although none of the calculations agree with the data in quan- calculations of Betz and Lee do not give reasonable titative detail, the work of Refs. 1, 3, and 4 agree values for the vector-analyzing power, since only the P33 reasonably well with both the cross sections and vector- channel is included in the nN amplitudes and since for analyzing powers at the lower energies. Of course, the the most part the vector polarization in nd scattering

76 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Gabathuler et al. Stanovnik et a I. Blankleider- Afnan Fayard etal. Rinat et al. Betz-Lee

T._.= l80MeV T= 256 MeV

• Smith etal.

-0.25 60 120 0 60 120 0° 60° 120° 180

Fig. 1. Comparison (Refs. 1-7) of current three-body calculations with measured differential cross sections and analyzing powers for nd elastic scattering.

arises from the interference between 5 and P waves in iTn becomes negative at forward angles, and this is not the nN amplitudes in this energy region. This considera- predicted by present three-body calculations, although tion of only the A channel may be responsible for the the prediction of Blankleider and Afnan is remarkably failure of this model to give an adequate account of the close in shape to the data. However, these new data do differential cross section. not exhibit negative values near 9= 130°, as suggested The discrepancy between the experiment and theory is by earlier data. The less oscillatory behavior of iTu greatest at Tn = 256 MeV. The vector-analyzing power weakens the argument for dibaryon-resonance behavior

November 1983 LAMPF USERS GROUP PROCEEDINGS 77 Los Alamos National Laboratory in this energy region. No other evidence for dibaryon- resonance effects exists in the nd system. Pion absorption in nuclei has emerged as a major issue in medium-energy physics. Although many measurements involving the nd—>NN reaction have been performed, the absorption process has not been explained adequately and the effect of pion absorption on the elastic amplitudes is poorly understood. To further investigate the effect of absorption on the

elastic channel, it is essential to focus on the Pn nN amplitude, since this amplitude is necessary for pion absorption. Mizutani et al.8 have emphasized that the

composition of the Pu nN amplitude into the pole and nonpole pieces is not known at present. The pole term is necessary for pion absorption whereas the nonpole amplitude contributes to pion rescattering in the nucleus. Experiments in nN scattering give a measurement of the sum of these two terms, whereas the relative strength of these two amplitudes is important in jt-nucleus scattering. The uncertainties in the composition of the />,, phase shift were demonstrated by Mizutani et al. and are illustrated in Fig. 2. Here, one can see that two very different sets of pole and nonpole phase shifts can give

rise to essentially the same KN PU phase shift. Previous experiments have imposed very little constraint on the Fig. 2. Comparison of two different sets of pole and pole and nonpole components of the Pu amplitude. n However, measurements of t2^ ' *w/ scattering are nonpole P(1 nN phase shifts (from Ref. 8) that give

expected to place an important restriction on the Pn rise to essentially the same total nN scattering amplitude. phase shift at low energies. b The sensitivity of /2'jJ to the Plt amplitude can be seen from the lower half of Fig. 3. Here, the angular b dependence of /^ is shown for 7",I=256MeV for discussed with regard to multiple-scattering and early several calculations. The primary differences among three-body calculations and led to an early interest in

these calculations are the manner in which the Pu measuring t20. The sensitivity of tI0 to the quadrupole amplitude is treated—that is, all of these calculations are form factor can be seen readily from a simple expression in good agreement, as shown in the upper half of Fig. 3, based OP. an impulse approximation. The expression is if the Pu amplitude is made to vanish! given in terms of the nN nonflip #(9) and spin-flip h (9)

Examples of the differences are that Rinat et al. use amplitudes as well as the ratio x of the quadrupole F2 to

both a Pu nN as well as a pN amplitude, whereas the monopple form factor Fo, Blankleider and Afnan and Fayard et al. employ only jtJV amplitudes. Moreover, the nNN coupling constants vary widely among the calculations. More discussion of this '20 =-( issue is given later in light of the present measurements of , lab '20 • The prospect of measuring the quadrupole form factor of the deuteron by observing t20 in nd scattering was

78 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory ANL-P-IT.ZTS ~ -(2) 0.5 Tr«256MeV BLANKLEIDER-AFNAN FAYARD «t al. RINAT etal. and thus depends critically upon x, the ratio of the quadrupole to monopole form factor. This dependence led several authors to sugge^. that tI0 in nd scattering at an angle of 180° would provide a measurement of the deuteron rf-state probability. Because the calculated values of t20 in nd scattering appear to depend strongly on the absorption, it is likely that the ratio .v might best be determined from t2a measurements in ed elastic scattering, and experiments 10 of this type have begun already at the Massachusetts Institute of Technology- Bates Linear Accelerator Center. However, if the absorption effect can be determined, nd elastic scattering would offer complementary information to ed scattering, particularly at high momentum transfer q > 3 fm~'. Unfortunately, there is some controversy1' concerning the measurements of t£b, which Willi Griiebler expressed (these proceedings), and I now discuss the experimental method and the results. 160

Experimental Method Fig. 3. The results of three-body calculations for t$ with The key feature for performing measurements of /jjb no P, i nN amplitude (upper panel), and the same in nd scattering is the development of a high-efficiency calculations with the P amplitude (lower panel). u deuteron tensor polarimeter. A prototype of the present This indicates the sensitivity of t\f to the P n polarimeter was used to perform the first measurement amplitude, and consequently to pion absorption. of tM in nd scattering; it is described in detail in Ref. 12. The present polarimeter was employed to measure (1) the first angular dependence13 of /^b in nd scattering, where x = F2/F0 and y = FjF0. Here, Fl is the di- h 10 pole form factor. At large scattering angles where (2) ?2'jJ in ed scattering for the first time, and (3) the 2 2 angular and energy dependence of t^ in nd scattering. | g | » | h | , then t is given by 20 Experiments and calibration procedures involving the new polarimeter are summarized in Table I.

Table I. Summary of Experiments with New Polarimeter.

Experiment Location Completion Date

Calibration Berkeley 88-in. cyclotron 1980, July nd-+nd(Exp. 483) Los Alamos (LAMPF, LEP channel) 1980, August ed+ed(Exp. 7920) MIT-Bates 1982, June Calibration check Los Alamos three-stage tandem Van de Graaff 1982, November nd—> nd (Exp. 673) Los Alamos (LAMPF, P3 channel) 1983, February

November 1983 LAMPF USERS GROUP PROCEEDINGS 79 Los Alamos National Laboratory Calibration of Polarimeter polarimeter for nonpolarized deuterons are shown as a function of energy for deuterons incident along the The polarimeter employs the 3He(tf,.p)4He reaction, central axis of the polarimeter. The calibration was which has a large cross section and tensor analyzing checked 2 years after the primary calibration by measur-

power T20 at forward angles and which has a large ing e0 again (see Table I) at the Los Alamos three-stage Q value, 18.4 MeV. The polarimetei was calibrated in a tandem Van de Graaff. These results are included in separate experiment at the Berkeley 88-in. cyclotron. The Fig. 4. We conclude from this test that the measurement

polarization of the deuteron beam was measured with of the efficiency €0 is reproducible to ~2%. respect to the well-known tensor analyzing power of 4 2- He elastic scattering at Ta = 35.0 MeV. The calibration of the polarimeter was determined as a function of Electron-Deuteron Elastic Scattering incident deuteron energies, position, and angle of incidence on the polarimeter. Further confidence in the present method can be

Typical results for the calibration are shown in Fig. 4. gained by examining the results of the t20 measurement in

Here, the analyzing power T20 and efficiency €0 of the ed elastic scattering, which was mentioned in Table I. The measurement with the present polarimeter was performed at low values of momentum transfer, q = 1.74 ANC-P-16,060 and 2.03 fin"1, at MIT-Bates. These measurements were performed as a feasibility study of the problems associated with performing polarization experiments in electron scattering at high momentum transfer. At low values of momentum transfer, reasonable models (Paris, Reid soft core, Hamada-Johnson, • BERKELEY Feshbach-Lomon) of the deuteron yield values of t20 that are in good agreement with one another. For example, X LOS ALAMOS effects such as meson-exchange currents and relativistic wave functions are expected to be relatively minor. It is especially gratifying that the present work agrees very well with these calculations, as shown in Fig. 5. This work provides additional confidence that the present

method of measuring /20 really is working. -0.6

Pion-Deuteron Elastic Scattering

The tensor polarization t^ of the recoil deuterons from Ttd elastic scattering was determined by measuring the efficiency e of the polarimeter for the scattered -1.4 b 20 22 24 26 deuterons. Then f2'2 was related to e and the calibration parameters Eo and T20 by the expression

Fig. 4. ,lab_ '20 ~ The results for the polarimeter efficiency for unpolarized deuterons (upper panel) for two separate calibrations, which were 2 years apart and The experimental apparatus designed to measure e is 3 performed at two different laboratories. The illustrated schematically in Fig. 6. Pions from the P -East analyzing power of the polarimeter is given in the channel at LAMPF were focused onto a liquid- lower panel. These results are for deuterons that deuterium target of thickness 2.5 or 5.0 mm. Recoil enter along the central axis of the polarimeter.

80 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory the 3He(d,p)4lle reaction from other sources of protons. The deuterons are defined by dEldx signals in the 51 and 52 detectors and by the time of flight between the -0.4 pion arm and 52. A contour plot of 51 vs 52 is shown in Fig. 7 for nd scattering at 7,= 134MeV and 9d = 18.O°. This kinematic condition was selected for illustration because t20 -0.8 Griiebler's results (these proceedings) in this energy and angular range show remarkable disagreement with the -PARIS (IA + MEC) present work. -1.2- ' •PARIS (IA) The contour plot shows a clear separation between -FL4.6 (IA + MEC) protons and deuterons incident on the polarimeter. The separation is even more dramatic than illustrated because the deuterons shown in the figure are prescaled by -1.6 a factor of 100 compared with the background protons. q (f nf') The protons from the 3He(rf,p)4He reaction are identified by first requiring a deuteron event and then dEldx in the Fig. 5. 53 scintillator, energy in the E scintillator, and time of The results of a measurement of tla for ed elastic Might between 52 and 53. scattering, in good agreement with existing calcula- This time of flight vs E is shown in the contour plot in tions. Fig. 8. The upper part of the figure indicates the results if no requirement is placed on the event that it be associated with a deuteron. Then, three distinct ridges pions were detected in an array of three plastic scin- emerge in the time-of-flight spectrum: (1) the tillators while the recoil deuterons were focused onto the 3He(d,p)AHe events are in the smallest ridge; (2) the polarimeter with a QQD system. protons that have a random pion in the pion arm lie in It is essential to clearly define the deuterons befor the center ridge; and (3) the largest component is the they enter the 3He volume, and to separate protons for protons from the (n,n'p) reactions that occur in time near

ANL-P-16,974

APPARATUS TO MEASURE t2Q IN ird SCATTERING

LIQUID-DEUTERIUM TARGET

VETO

7T3 7T2

J WEDGE E *l M 8. DEGRADER CELL Si (Li)

Fig. 6. b Schematic of the apparatus to measure (2'j; .

November 1983 LAMPF USERS GROUP PROCEEDINGS 81 Los Alamos National Laboratory ANL-P-I7.Z73

TT=l34MeV

lOOOr Fig. 7. Contour plot of dE/dx signals in scintillators 51 and 52. The deuterons incident on the 500- polarimeter are clearly separated from background protons. (No previous software cuts are placed on this spectrum.)

PULSE HEIGHT IN SI (channels)

ANL-P-17,274 VI34MeV

Fig. 8. Contour plot of the time of flight between detectors 52 and 53 vs the pulse height in detector E. The upper part indicates the proton spectra before any software cuts are placed on the 51-52 spectrum shown in Fig. 7. The protons from 3He(rf,p)4He are -20 TIME OF FLIGHT S2-S3 clearly visible without the software filter on (ns) deuterons. The lower figure illustrates the results with a filter only on 51 and 52. 1024 FILTERED BY Si-S2

100-

-20 TIME OF FLIGHT S2-S3 (ns)

82 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory the edge of the coincidence window of the pion and size at SIN is comparable with the polarimeter aperture, deuteron signals. Since these latter events occur near the it is possible that particles identified as deuterons enter- edge, the timing is shifted relative to the proton peak by ing the polarimeter hit a wall and never enter the 3He ~15 ns, the width of the 51-52 pulse. A contour filter on volume. This would result in a low-efficiency e and a 51 and 52, our most powerful filter, eliminates both more positive ?Jjjb. Clearly there is a geometry- components of background protons so that only the dependent correction to be made in the SIN experiment. 3He(d,p)4He ridge remains, as shown in the lower part of Since the deuteron trajectories are not measured in the Fig. 8. (We note that the filters that define the deuteron actual experiment, this effect might lead to the observed events in the SIN experiment are made by hardware disagreement. discriminator thresholds on their Q and R detectors and This problem is avoided in the LAMPF experiment in time-of-flight signals.) These spectra exhibit little back- two ways: (1) the aperture of the polarimeter is approx- ground, and further software cuts on 53, E, or pion time imately 3 times larger, as mentioned; and (2) two x-y of flight are redundant. This redundancy is lost for the wire chambers measure the trajectory of each deuteron data at Tn = 256 MeV and these filters become signifi- entering the polarimeter. The wire chambers are used at cant. the beginning of each run to tune the QQD system and

The final results at 6d= 18.0° are shown in Fig. 9. to align the polarimeter with respect to the deuteron There is no dramatic energy dependence in the data from beam. The second difference is that the energies of the 11 14 134 to 256 MeV. The results ' 9d = 15.0 and 20.0° deuterons incident on the LAMPF polarimeter are from SIN are shown also in the figure for comparison. measured by scanning the polarimeter aperture with 2.0- Clearly, there is remarkable disagreement between the and 3.0-cm-diam Si(Li) detectors. present work and that discussed by Griiebler. The importance of measuring the deuteron energy Although the exact cause of the discrepancy has not accurately can be seen from the rapid energy dependence yet been determined, it is useful to compare the two of e0 in Fig. 4. In the SIN experiment the deuteron methods in more detail. The main differences between energies are determined by allowing the deuterons to our method and that of the ETH group reside in the range out in aluminum foils. Although this method is polarimeter itself. Here, I highlight only two major generally accepted for finding the centroid of the deu- differences. First, the aperture of the SIN polarimeter teron energy spectrum, it is somewhat problematic to (3.0 cm) is approximately 3 times smaller than the determine the spectrum of deuteron energies. This is LAMPF polarimeter (8.9 cm). Since the deuteron beam important since the width of the deuteron energy spec-

trum at 7"d = 20MeV is typically 6 MeV in the SIN experiment. Of course, with the use of Si(Li) detectors ANL-P-17,272 this problem is avoided in the LAMPF experiment. 0.8 i 1 • 1 l8 0d= °J 0.4 PRESENT WORK, *% - 0 Results and Discussion fGRUEBLERetal. d c - 0.4 The final work is shown in Fig. 10 for Tn= 142, 180, 220, and 256 McV. The results are compared with the 0.8 t ] theoretical calculations of Blankleider and Afnan,2 Betz 1.2 and Lee, Fayard et a!.,3 and Rinat and Starkand.4 In addition, the dotted curve in the figure represents the 1.6 , i i 1 . 1 120 160 200 240 Blankleider-Afnan calculation with no Pn nN channel. (MeV) Omitting this channel has the effect of both removing

absorption and Pn nN rescattering from the calculation. Fig. 9. The remarkable result is that the present work is in best b Present measurements of *2'(J for a deuteron recoil agreement with the calculations that have no Pu chan- angle of 18.0° (darkened circles). These are com- nel. This observation is supported by the measurements

pared with the work of Refs. 11 and 14 at 8d = 15.0 of differential cross section and iTu at T7I= 142 MeV. and 20.0°'.

November 1983 LAMPF USERS GROUP PROCEEDINGS 83 Los Alamos National Laboratory MH.-P-IT.ua ANL-P-IT,2T6 o.5r 142 MeV 220 MeV r = 142 MeV • GABATHULERetol. 100- x STANOVNIK «tol. - a HOLT«tal. (1979) p . _•_ BLANKLEIDER-AFNAN — u IBLANKLEIDER "'•°r NO p, No FjJ-AFNAN FAYARDatal. RINAT etal. H—I—^ 10

-1.5 >.*v*E¥ 40° 80° 120° I6Cf 0° 40° 80° 120° 160° ' I I ' I • SMITH etal. 0.50- Fig. !0. Present measurements of t£b (darkened circles), and the previous measurements of Ref. 13 (open 0.25- circles). The results agree best with the calculations

that contain no Pu nN amplitude, the dotted curve. 60° 120° 180° e:.cm. The available data for nd elastic scattering at Tn= 142 MeV are shown in Fig. 11. The solid curve in Fig. 11. the figure represents the full calculation of Blankieider Data points representing measurements of the and Afnan; the dotted curve, the calculation with no Pn differential cross section (upper panel) and vector- nN amplitude. Clearly, the calculation with no Pn gives analyzing power (lower panel) at T^ts 142 MeV. better agreement with the data. Again, the data seem to be in best agreement with A similar result is obtained with the calculations of the calculations with no Pu nN amplitude. Fayard et al. and Rinat and Starkand. At higher energies the result is not as striking as at 142 MeV. In fact, at

256 MeV there is worse overall agreement if the Pn absorptive amplitude that is believed to have the domi- channel is removed from the Blankleider-Afnan calcula- nant effect on the elastic channel occurs in the LNA = 2, tions. This may be an indication that the energy de- /" = 0+ channel. Thus, in terms of the calculation, + pendence oi the Pu amplitude is in error as well as the elastic-scattering data indicate that the 0 absorptive magnitude. Unfortunately, there are many open ques- channel is in error, while no claim is made about the 2+ tions at this high energy and no firm conclusions can be channel, which gives rise to most of the true absorptive drawn. On the other hand, at Tw= 142 MeV one might cross section. expect the theoretical calculation to be more reasonable A question that naturally arises from this work is since the momentum transfer is relatively small whether or not nd elastic scattering would be sensitive to 1 q < 2 fm~' and the deuteron wa function and AW possible dibaryon-resonance effects since elastic scatter- interaction are then reasonably v^ii known. Moreover, ing appears to be weakly dependent on the absorption dependence of the deuteron wave ; nction on relativistic channel and since the predicted dependence favors low corrections is not substantial at the lower energy. relative orbital angular momentum in the intermediate

Although omitting the Pn channel from the calcula- NN channel. In fact, Afnan and Blankleider predict that tion is a somewhat drastic measure, especially since the intermediate AW channel with Z,NN = 0 should have absorption is removed, it may not be as unreasonable as the dominant effect on elastic scattering. At present, the it appears. Afnan and Blankleider have shown that true evidence indicates that the nd elastic-scattering channel pion absorption can be expected to proceed primarily is not well suited for studies of possible dibaryon + through the LN& = 0 and J" = 2 channel, whereas the resonances.

84 LAMPF USERS GROUP PROCEEDINGS November 1983 JLos Alamos National Laboratory Another question that may now be asked is whether or 3. C. Fayard, G. H. Lamot, and T. Mizutani, Phys. not the quadrupole form factor of the deuteron can be Rev. Lett. 45, 524(1980). measured in nd scattering if absorption has a small effect on elastic scattering. 4. A. S. Rinat and Y. Starkand, Nucl. Phys. A 397, 381 (1983).

Conclusions 5. K. Gabathuler et a!., Nucl. Phys. A 350, 253 (1980).

The energy dependence of t\^ was measured in the 6. A. Stanovnik et al., Phys. Lett. 9413, 323 (1980). range TT= 134-256MeV. There is remarkable disagreement with the work at SIN: near Tn = 140 MeV we 7. G. R. Smith et al., Tenth Int. Conf. on Few-Body b observe a negative /2'jJ za -0.6, whereas the ETH group Problems in Physics, Karlsruhe, Germany, 1983; J. observes a positive t^b« 0.2. In the present work no Bolger et al., Phys. Rev. Lett. 48, 1667 (1982), and unusually dramatic energy dependence of ^jjb was 46, 167(1981). observed, and currently there is no apparent evidence for dibaryon-resonance effects in nd scattering. The 8. T. Mizutani, C. Fayard, G. H. Lamot, and S. measurements of Z^1" are m best overall agreement with Nahabetian, Phys. Rev. C 24, 2633 (1981). the calculations in which the Pn nN amplitude has been omitted. This suggests that the effects of pion absorption 9. W. R. Gibbs, Phys. Rev. C 3, 1127 (1971). are not properly taken into account by the existing theories. 10. M. E. Schulze, D. Beck, M. Farkhondeh, S. Gilad, S. Clearly, more theoretical effort is necessary to under- Kowalski, R. P. Redwine, W. Turchinetz, R. J. Holt, stand this simplest n-nucleus process, nd elastic scatter- J. R. Specht, K. Stephenson, B. Zeidman, R. M. ing. Future measurements of nd scattering should focus Laszewski, E. J. Stephenson, J. D. Moses, M. J. on polarization studies that cover a broader angular Leitch, R. Goloskie, and D. P. Saylor, Tenth Int. range and achieve a higher accuracy. Conf. on Few-Body Problems in Physics, Karlsruhe, Germany, 1983.

Acknowledgments 11. W. Gruebler, J. Ulbricht, V. Konig, P. A. Schmelzbach, K. Elsener, C. Schweizer, M. The collaborators for this experiment are W. S. Merdzan, and A. Chisholm, Phys. Rev. Lett. 49, 444 Freeman, D. F. Geesaman, J. R. Specht, E. Ungricht, B. (1982), and the Fifth Int. Symp. on High-Energy Zeidman, E. J. Stephenson, J. D. Moses, M. Spin Particles, Brookhaven National Laboratory, Farkhondeh, S. Gilad, and R. P. Redwine. In addition, 1982. we thank K. Stephenson, J. S. Frank, and M. J. Leitch for their substantial part in developing the new 12. E. J. Stephenson. R. J. Holt, J. R. Specht, J. D. polarimeter. Moses, R. L. Burman, G. D. Crocker, J. S. Frank, This work was supported by the United States Depart- M. J. Leitch, and R. M. Laszewski, Nucl. Instrum. ment of Energy under Contract W-31-109-Eng-38. Methods 178,345(2980).

13. R. J. Holt, J. R. Specht, K. Stephenson, B. Zeidman, REFERENCES J. S. Frank, M. J. Leitch, J. D. Moses, E. J. Stephenson, and R. M. Laszewski, Phys. Rev. Lett. 1. B. Blankleider and I. R. Afnan, Phys. Rev. C 24, 47,472(1981). 1572(1981). 14. V. Konig et al., Tenth Int. Conf. on Few-Body 2. M. Betz and T.-S. K. Lee, Phys. Rev. C 23, 375 Problems in Physics, Karlsruhe, Germany, 1983. (1981).

November 1983 LAMPF USERS GROUP PROCEEDINGS 85 Los Alamos National Laboratory NUCLEON NUCLEON PHASE-SHIFT ANALYSIS UP TO 800 MeV

C. Lechanoine-LeLuc University of Geneva, Switzerland

Catherine Lechanoine-LeLuc

Introduction have come primarily from TRIUMF and LAMPF, and clearly some more np data are needed. Currently existing AW data1 provide the possibility of In this report I concentrate on the Saclay-Geneva performing energy-dependent phase-shift analyses in the phase-shift analysis.* A comparison with the most energy region 10-800 MeV. For pp scattering the situ- recently available analyses3' is given. ation has greatly improved within the last 5 years because of the extensive work done mainly at LAMPF and SIN. Above this range there are only a few separate Formalism energies where the pp data are sufficient for an energy- independent analysis (for example, at 1000 MeV). This The amplitudes used in our analysis are the so-called should be remedied, however, by the ongoing work at invai'ant amplitudes a,b,c,d,e. They are related to those SATURNE II. For np scattering the situation is not as used by the authors of Refs. 3 and 4, and the relations satisfactory; here the amount of complex polarization data is about 6 times less, and this, mainly below 'Reference 2. Work was done in collaboration with 500 MeV and at angles greater than 50° cm. Results J. Bystricky and F. Lehar.

86 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory between them can be found in Ref. 5. The development where To is a fixed kinetic-energy value within the of these amplitudes into partial waves Ru and nuclear interval and where aUn are fitted parameters. The aUn bar phase shifts 5U is given in Refs. 5 and 6. The S- can be interpreted as the phase-shift value for T= To and matrix parameterization is then given for the singlet the value of the first, second, and third derivative of 5U l l ] states ( S0, Px, Z>2...) and for the triplet-uncoupled with respect to Tat point T= To. 3 3 states ( P,, D2,...)by Above the inelastic production threshold, the phase shifts can be complex. The imaginary part of these phase shifts is then written or (1)

"Un n Im8u(T) = (T-Tu) for T>TU , (4) 3 3 and for the triplet-coupled states ( 5,, ex, D,,...) by ~nT

2 5 1 •tos2eJe '' -'- "' 5 = . (2) 2i - i sin 26j Jl*M cos 2€j e

where €j is the mixing angle. where the threshold energy u is proper to each phase One-pion exchange is included through partial-wave shift and where the aU are treated as variable contribution*: to the unsearched waves for / > Jmn = 6. parameters. If the threshold energy Tu falls below the The pion-nucleon coupling constant/2 is introduced as a lower energy limit of the interval, the form of the energy fixed parameter (=0.08). dependence of ImbLI coincides with that of ReSu. Many The Coulomb amplitude is introduced in Ref. 7. For authors instead use an absorption coefficient T), angular momenta L higher than Lmax (=6) we have also added magnetic-moment corrections according to Breit (Ref. 8). This correction takes into account the elec- (5) tromagnetic interaction between the charge and magnetic moment of interacting particles and the form-factor contribution. This correction only influences the e giving inelasticities that are not in degrees but that are amplitude. dimensionless between 1 and 0. 2. First, the isospin /= 1 phase shifts were determined on the basis of pp data. The total number of Principle of Analysis individual data points in the four intervals is 5294. The pp data are well distributed between different experimen- Our analysis has the following characteristics. tal quantities and the resulting energy dependences of the 1. We have divided the energy range from 10 to phase shifts are smooth functions of energy. 800 MeV into four overlapping intervals (10-220, 3. The pp phase shifts, recalculated for np 140-450, 380-610, and 520-800 MeV). In each of them kinematics, are then used as fixed input in the np (pn) our energy expansion of the phase shifts 5LJ allows two analysis, where only the / = 0 phase shifts are calculated extremes, which permits a good fit of possible structures. from np and pn data. The 6030 experimental points The expansion used is (72% are differentia] cross sections) were used. The lack of forward-scattering experiments was compensated for

3 by introducing as "experimental data" the ratio of the real to imaginary part of the spin-independent forward- (3) 9 «=0 scattering amplitude calculated by Grein.

November 1983 LAMPF USERS GROUP PROCEEDINGS 87 Los Alamos National Laboratory 4. An important aspect is how information on the SIN.15'16 (Similar measurements will be avail- inelastic channels above the pion-production threshold is able at 470, 490, 515, 540, and 560 MeV and at introduced. In the energy region between 290 and a few energies between 240 and 400 MeV). 1000 MeV there exist only 8 independent measurements It is worth mentioning that the University of Geneva, of the total pp inelastic cross sections; on the other hand, working at SIN, has made a special effort toward the about 160 measurements of different inelastic-channel completeness of the data rather than separate individual cross sections are known. To use this information, we measurements. This has resulted in a largely over- have fitted the energy dependence of each reaction total determined complete set of spin-dependent parameters at cross section by polynomials in T. The total inelastic five energies between 34 and 90° cm., allowing a direct cross section was then calculated as a sum of all the reconstruction of the five complex scattering amplitudes^ reaction cross sections and introduced into the phase- Before performing the experiment, a careful study 17 shift analysis in 5-MeV steps with the calculated errors. was done to choose parameters to measure that would A similar calculation was applied to the np inelastic total assure an unambiguous reconstruction, taking into ac- cross sections. Here, the isospin invariance was not count theoretical and experimental requirements. The taken into account. Therefore, imaginary phase shifts in first direct amplitude reconstruction was published in 7 = 0 were allowed. i R 5. In addition, a fixed pp phase-shift analysis was 1981 at 579 MeV, providing an amplitude reconstruc- performed at 1 GeV where four different solutions were tion completely independent of any model and in ex- found (535 data points used in the energy interval cellent agreement with phase-shift analysis. Figure 1 960-1040 MeV). shows the same reconstruction at 445 MeV along with the phase-shift analysis predictions. ig • AaT — from TRIUMF (final va'ues) ; from LAMPF at 487, 639, and 791 MeV20; and from Data Base SATURNE II.21 22 The experimental data for the present analysis were • AcL — from LAMPF, from TRIUMF (final taken mainly from the compilation of Ref. 1. To denote values),19 and from SIN final results.23 the experimental quantities, we use a fo\r-subscript notation, Xa^y §, where a,P,y,6 refer to the spin oiiinta- Normalization factors multiplying measured data tion of the scattered, recoil, beam, and target particles, were introduced as variable parameters, mainly for respectively. Some recently appearing data also have differential cross sections. They were kept only if their been included as follows. influence was significant. Such normalization factors also were applied on AaL and AaT measurements. pp Scattering Figure 2 illustrates the experimental situation for AoL. A rather good agreement is observed between • Spin-correlation Aookk measured at 13 energies 24 22 23 at LAMPF.10 Argonne, LAMPF, and SIN results when the systematic errors quoted by the authors are considered. • Spin-correlation Aoonn measured at 90° cm. at A more severe discrepancy is observed with the LAMPF.11 TRIUMF19 results, which are systematically higher except for the two lowest energy points. We have • Differential cross section at small angles therefore chosen to normalize all the data on our SIN23 measured at Gatchina.12 results in the "500" interval where there is the most • Preliminary SATURNEII results on A at overlap between the different groups. five energies.13 A small normalization factor was found for the LAMPF data, 1.068 as compared with 0.78 for • Analyzing power, Wolfenstein parameters, and TRIUMF data. For the Argonne data a common spin-correlation A0^n measured at LAMPF at W normalization factor for AoL and Aookk was applied 650 and 800 MeV. separately at each energy. These normalization factors were then used in the other intervals as fixed parameters, • The polarization Pnooo and the spin-dependent except for the TRIUMF data at 202.7 and 325.4 MeV parameters Dnono, Knoon, Ds,oso, Ds,oku, Ms,osn, where almost no normalization is required. These two and Ms,okn at 448 and 579 MeV measured at

88 LAMPF USEBb viROUP PROCEEDINGS November 1983 Los Alamos National Laboratory lei S.B 445 MeV 4.0

1.0

« « S4 an ?* m '

Fig. I. Direct experimental reconstruction of the scattering amplitudes at 445 MeV. The full line is Saclay- Geneva phase-shift-analysis predictions. All amplitudes are normalized using |e| real.

points were therefore omitted. For A

tcrs are applied. The AoT exhibits the same energy

30 -

20 / V

'i - 1I 10 • '• J a

200 400 600 800 1000 T (MeV)

Fig. 2.

Compilation of available pp results on AoL (total) as a function of kinetic energy T. The full line shows Saclay-Geneva phase-shift-analysis predictions. Experimental points shown are data from TRIUMF O (Ref. 19), SIN X (Ref. 23), LAMPF A (Ref. 22), and Argonne :: (Ref. 24). The new SATURNEII • data, not yet introduced in the phase-shift analysis, are shown for completeness.

November 1983 LAMP? USERS GROUP PROCEEDINGS 89 Los Alamos National Laboratory np Scattering Several incompatible data sets exist in np scattering. The main disagreement is in the shape of the angular • The polarization parameter at 665 and 29 25 dependence of A measured at TRIUMF and A 738.8 MeV measured at KEK. oono ooon from LAMPF.30 In this case, normalization could not 26 • The AoL measurements at Argonne. completely remove the discrepancies. Both sets of data were kept with free normalization. • Aooon and AIOIW from Dubna.27 Altogether, 5294 independent pp data points and 6030 K 28 • onno' Kok«so, and Kos,,so from LAMPF. np data points were analyzed, as illustrated in Table I. In each of the four intervals, typical %2 data points were of

Table I. Summary of pp and np {pn) Data Between 10 and 800 MeV Used in the Phase-Shift Analysis. pp Data np/pn Data

Experiment Data Points (%) Experiment Data Points 17OJ

elastic a 453 7.5 opt 2.9 5 0.08 °inel 100 1.7 a = Re/Im 16 0.27 1.2 do/rffi 4328 371 71.8 P 809 13.4 cte/cKl 2017 38.1 19 P 1490 28.1 ~ nono o _ n 13 ~ s'oso 288 A=D, , 12 nono s'oko R=D 209 80 s'oso T~ onno 5.3 A=D 168 65 's'oko RT=Kos"so 20 13.5 38 R' = Dk'oso A D 7 ' = k'oko KT-Kok"so 17 R,R' 17 AT=Kok'ko 3 A.R 5 A 72 331 oonn c 9 15 14.3 a's"oo 262 Aooss A 141 Aookk oosk, M,sosn 48 48 1.8

ns"so

Sum 5294 Sum 6030

Spin dependent . Spin dependent 18.9% Spin independent 59% Spin independent

90 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory the order of 1.2/1.3 for pp, and slightly higher, 1.4/1.5, The Argand diagrams for the complex phases have for np. been studied: anticlockwise energy dependence is ob- l 3 served in the D2 phase, but the F3 phase is still increasing at 800 MeV, as can be seen in Fig. 7. Results We have investigated the well-pronounced structure observed in the experimental quantities AaL(tot), The energy dependence of the S, P, D, F, G, and H AoT(tot), and Aoom at 90° cm. around 750 MeV phase shifts and the mixing parameters together with (corresponding mass, 2.22 GeV) in terms of singlet- error bars are shown in Figs. 3-6 and compared with triplet amplitudes Mik. We found that the crossing of the Arndt's (dash-dotted line) and Dubois' (squares) analy- imaginary part of the spin-singlet amplitude through zero ses. The dotted line on the figures for higher partial waves at 750 MeV is responsible for the observed structure. are one pion exchange together with magnetic-correction During the np phase-shift analysis we have also tried 1 contributions. At lower energies, they compare well to to determine the pion-nucleon coupling constant f . The the fitted phase shifts. results in the four intervals follow. In' pp scattering a rather smooth continuation is observed between the different intervals. The four points Energy Interval 2 at 1000 MeV are\our four different solutions; two of (MeV) f 3 them are rather close. Note that for the P2 phase shift, two of them coincide whereas the two remaining are out 10-220 0.0742 ± 0.0048 of scale. Small discontinuities in pp phase shifts have a 140-450 0.0677 ± 0.0011 strong influence on the np analysis. In the np (pn) 380-610 0.0775 ± 0.0013 scattering, rather strong oscillations are still observed, 520-800 0.0768 ± 0.0010 showing the need for more data. The thresholds of the imaginary parts of S, P, D, and The coupling constant corresponds principally to the F waves were studied for pp and np, as well as G waves exchange of charged pions (np charge exchange) because l 3 for pp. The thresholds of the Im S0 and Im F4 are it is determined mainly by the large number of differen- higher than 800 MeV (even in the 1000-MeV solution the tial cross sections in or near the backward direction. In 3 contribution of Im F4 is negligible); the contribution the lowest energy interval this constant cannot be well 3 from the Im Pl wave is negligible up to 800 MeV. For determined, the n pole being far from the physical region 3 np the dominant inelasticity is found in Im D2 at low (1.26 at 80 MeV, 1.08 at 260 MeV). A slight energy energy, and no need for inelasticity other than Im 3Z>,, dependence is observed in the other intervals, the con- 3 Im D2 was found. stant approaching with energy to the value of 0.08 The different available recent phase-shii.. analyses known from np scattering. show good agreement for pp scattering up to 450 MeV, although there are still small discrepancies below—that is, in the 62 parameter. At higher energies, Arndt's Conclusion solution is smoother than ours. However, we have a better agreement with Dubois. A reason might be Our analysis of /= 1 phase shifts determines well the the absence of some of the Geneva group measurements phase shifts up to 580 MeV, the highest energy where in Arndt's analyses. intensive measurements of Geneva University are avail- At 800 MeV the differences in all three analyses are able. Some uncertainties remain at higher energies but most important, but these discrepancies are even more should be solved with the present approved experiments. striking in the imaginary parts. A general agreement is The lack of data between 800 and 970 MeV makes it 3 l found for Im F3 and Im D2 up to 600 MeV. The dashed difficult to extend the energy-dependent phase-shift lines are predictions calculated from the Paris analysis up to 1 GeV. With the planned experiments at 31 potential. Their prediction for Im 'Z)2 has the right LAMPF, SIN, and SATURNEII, the pp phase shifts shape, even if the potential was intended only for F and will be well determined up to 1 GeV. More data are 3 higher waves. The major disagreement comes in the P0 clearly needed at higher energies from SATURNE II, and 3P, waves. where Wolfenstein parameters would be desirable.

November 1983 LAMPF USERS GROUP PROCEEDINGS 91 Los Alamos National Laboratory I'll

40 \ 'S

20. - ^V -

20.

40.

T MeV 1 , t , 1 , 1 • t 1 ' 1

c ! - i 3Po 1 . 4. - -

2. - • -

-20. z -2. -40. - - \ -4. \ \ -ao. - - -C. TMeV " -ao. _

1 ' 1 ' 1 ' 1 ' -ico. I - i TMeV I -120. 1 . 1 1 i 10. - -

0. s I -10.

TMeV i -70. i . i . i . i

1 1 ' 1 ' 1 ' 1 1

33 B • s^*—""" " -•-. ~-.

-20. _ _

-40. - -

-to. - Fig. 3. The real part of pp phase shifts in degrees. The TMeV dash-dotted line represents predictions from Arndt et al. •ao. (Ref. 3), and the squares, Dubois (Ref. 4). The dotted line shows one-pion-exchange contributions.

92 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory i T 3F« - D 1 ? '

1-1 M J 1 i ^^^ ~'T" 1 J 1 -

TMeV TMeV i . i , i 1 | 0. 200. 400. 600. >90. 1000. 400. 690.

i tm 3Po

- -

/ J MeV i . i .y. • 0. 200. 7 SOS. 10S0. 0. 200. 400. 600. tOO. IOCS.

Im 3F 2 i -i

TMeV

200. 400. GOO. SCO. 1CC0. 200. 400 B20. 600. Fig. 4. Same as Fig. 3 but also for imaginary parts of pp phase shifts. The dashed lines are predictions calculated from the Paris potential (Ref. 31).

November 1983 LAMPF USERS GROUP PROCEEDINGS 93 Los Alamos National Laboratory 1 ' * 1 ' 1 " t

100 t- 1

•0 - \

•0

40. - \ -

20. -

o 0. 200. 400. «0O. too. 1000

20.

40. 1 . 1 , ^~"*-—*TM~eV7' 0. 200. 400. fOO. tOO. 1000.

0. . , . | I ' 1 ' 1

-10. - \ -

-20. -

0. 200. 400. iOO. tOO. 1000. -30.

J * i *i.l" Tl^eV- ' 2 -40. 1 ' •' ' t i ' 0. 200. 400. IGO. 100. 1°00. 0 ^ , .

-2. -

-4.

-f.

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0. 200. 400. (00. (00. 1000

\ ' ' ' 3 ' ' ' ' '

\\ -10

-20. -

0. 200. 400. tOO. tOO. 1000. -30. Fig. 5. ^^•TMeV_^ 1,1. -40. Same as Fig. 3 but for / = 0 phase shifts. 0. 200. 400. tOO. 100. 1000.

94 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory i • i 1 3G 3 2 : 3 1 G5 -

II 4 - -

-2. - 2. -

-4. ft

-t. -2.

...

10. -«. TMeV " TMeV " I.I.I -*. i i * 0. 200. 400. 100. 400. 1000. 0. 200. too. too. :ooo.

I 1 ' i 3 12. G4 .... 10. - J' - . -

6. -

2. -

0. 7 TMeV -2. I.I, 1 i 0. 200. 400. tOO. (00. 1000. o. 200. 400. too. aoo. 1000.

1 1 1 Im j

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T MeV 0. , 1 1 200. 400. E00. SOO. 1000. 200. 400 600. SOO. 1000.

Fig. 6. Same as Fig. 5.

November 1983 LAMPF USERS GROUP PROCEEDINGS 95 Los Alamos National Laboratory --0.2 X

-0.2 0.2

Fig. 7.

Argand diagrams for F3 and 'D2 waves. The symbols are the same as in Fig. 3.

The np data give less definite / = 0 phase shifts, even 4. R. Dubois et al., Nucl. Phys. A 377, 554 (1982). below 500 MeV. Some small-angle measurements are absolutely needed (that is, IKAR at SATURNEII). A 5. J. Bystricky et al., J. Phys. (Paris) 39, 1 (1978). crucial point for the determination of isospin 7=0 imaginary parts of phase shifts will be solved by a precise 6. H. P. Stapp et al., Phys. Rev. 105, 302 (1957). measurement of the partial total cross-section np —• npn" reaction. This reaction (except for one point measured at 7. N. Hoshizaki, Prog. Theor. Phys. Suppl. 42, 107 32 970 MeV at Birmingham ) has never been measured (1968). using free neutrons. The present LAMPF experiment on Aooss, Aookk, and Aooks is anticipated with great interest 8. G. Breit and H. Ruppel, Phys. Rev. 127, 2123 and will definitely improve the situation. But we think (1962). that additional measurements below and above 500 MeV of Wolfenstein parameters (Donon, Dos,,os, Dos,,ok, and 9. W. Grein, Nucl. Phys. B 131, 255 (1977). Kos,,so) are needed. Only 319 complex spin observables exist in this energy range, ~6 times less than what will be 10. S. J. Stuart, thesis, Los Alamos National Laboratory available in the pp system. An experimental effort in this report LA-9504-T (August 1982). direction is needed. 11. T. S. Bhatia et al., Phys. Rev. Lett. 49, 1135 (1982).

REFERENCES 12. A. V. Dobrovolsky et al., Nucl. Phys. B 214, 1 (1983); and V. A. Andrew et al., Yad. Fiz. 35, 1457 1. J. Bystricky and F. Lehar, "Nucleon-Nucleon Scat- (1982). tering Data," Fachinformationszentrum Karlsruhe No. 11-1, Parts I and II (1978), and Nos. 11-2 and 13. J. Bystricky et al., contribution to the Ninth Int. 11-3 (1981). Conf. on High-Energy Physics and Nuclear Struc- ture (ICOHEPANS), Versailles, France, 1981. 2. J. Bystricky et al., Saclay report DPhPE 82-12 (1982). 14. M. W. McNaughton et al., Phys. Rev. C 24, 1778 (1981); and Phys. Rev. C 26, 249 (1982). 3. R. A. Arndt et al., Phys. Rev. D 28, 97 (1983).

96 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory 15. E. Aprile-Giboni et al., AIP Conf. Proc. 95, 193 24. I. P. Auer et a)., Phys. Lett. 67B, 113 (1977). • (1982), G. M. Bunce. Ed. 25. M. Sakuda et al., Phys. Rev. D 25, 2004 (1982). 16. E. Aprile et al., Phys. Rev. D 27, 2600 (1983). 26. I. P. Auer et al., Phys. Rev. Lett. 46, 1177 (1981). 17. D. Besset et al., Nucl. Instrum. Methods 148, 129 (1978). il. Y. S. Bagaturiya et al., Sov. J. Nucl. Phys. 33, 659 (1981). 18. E. Aprile et al., Phys. Rev. Lett. 46, 1047 (1981). 28. R. D. Ransome et al., Phys. Rev. Lett. 48, 781 19. J. P. Stanley et al., Nucl. Phys. A 403, 525 (1983). (1982).

20. W. R. Ditzler et al., Phys. Rev. D 27, 680 (1983). 29. A. S. Clough et al., Phys. Rev. C 21. 988 (1980).

21. J. Bystricky et al., contribution to the Ninth Int. 30. C. R. Newson, thesis, University of Texas at Austin Conf. on High-Energy Physics and Nuclear Struc- (August 1980). ture (ICOHEPANS), Versailles, France, 1981. 31. J. Cote et al., Nucl. Phys. A 379, 349 (1982). 22. I. P. Auer et al., Phys. Rev. D 24, 2008 (1981). 32. A. P. Batson et al., Proc. R. Soc. London A 251, 23. E. Aprile et al., to be published in a Saclay preprint. 218(1959).

November 1983 LAMPF USERS GROUP PROCEEDINGS 97 Los Alamos National Laboratory A STUDY OF NEUTRINO-ELECTRON ELASTIC SCATTERING

R. C. Allen, V. Bharadwaj, G. A. Brooks, H. H. Chen, P. J. Doe, R. Hausammann, H. J. Mahler, A. M. Rushton, and K. C. Wang University of California, Irvine

T. J. Bowles, R. L. Burman, R. Carlini, D. R. F. Cochran, J. S. Frank, E. Piasetzky, and V. D. Sandberg Los Alamos National Laboratory

R. L. Talaga University of Maryland and Los Alamos National Laboratory

Presented by H. H. Chen University of California, Irvine

Abstract

The University of California, Irvine/Los Alamos Exp. 225 is currently taking data at the LAMPF beam-stop neutrino facility. Goals of this experiment are to study neutrino-electron elastic scattering; to search for anomalous sources of ve's from the beam stop—for + + example, from vu -*• ve oscillations, or u —>- e vtvu as allowed by the multiplicative lepton-number-conservation law; to study the inverse beta reaction on 12C; and to search for neutrino decays. Initial studies show that cosmic-ray backgrounds are being kept to the level of the expected neutrino-electron elastic-scattering signal and that beam-associated events occur approximately at the expected rate.

Introduction

At present the LAMPF accelerator delivers typically a 0.9-mA proton beam at 800 MeV. This beam passes through a sequence of meson-production targets and isotope-production targets in Line A before ending at the Herbert H. Chen beam stop. The residual proton current at the be n stop is about 0.68 mA with proton energy about "^jMeV, Neutrinos are produced in the beam dump from depending on the particular targets inserted upstream. + + The LAMPF accelerator operates usually at a macro decays of stopped 7t 's and stopped u 's. Because of the duty factor of either 6 or 9%—that is, it delivers either long pion and muon lifetimes relative to the LAMPF 80 or 120 macropulses per second of 750 us each. The beam microstructure, the neutrino source time structure macropulse consists of micropulses that are 0.25 ns wide follows the LAMPF beam macrostructure and duty separated by 5 ns. factor. The neutrino types and spectra are shown in Fig. 1.

98 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory 1 1 1 1 1 1 Table I. Neutrino Fluxes and Rates for Exp. 225.

1 + ^ — Proton energy 760 MeV /\ Proton current 600 uA / / \ + a / \ • Stopped n decay/proton 0.065 o / f : UaJ. / / \ Stopped it decay rate 2.4 x 10" s~ \ b 2 2 1 CO / / ve flux at 9 m 2.1 x 10' cm" day" / / \ 2 Enhanced v flux c 2.9 x 10' cm"2 day"1 / / \ e \ / / r> d / / \ KV-A 2.7 day-' 1 / / \ - 0.18 (mA-h)- ui / / \ • z / / \ /vWSG (sinow = 0.23) 1.8 day"' / / \ 0.12 (mA-h)-1 \ ^r i i t i till 7.4 day"' 10 20 30 40 50 60 1 NEUTRINO ENERGY (MeV) 0.51 (mA-h)-

Fig. 1. "Measured for 720-MeV protons in an instrumented beam stop Neutrino types and spectra from the LAMPF (Ref. 2): then scaled to 760 MeV from a comparison with the beam-stop neutiino source. results of a Monte Carlo calculation.

''The vu and vu fluxes are each equal to the ue flux.

The LAMPF beam-stop neutrinos are one-third ve's, cThe 20cm H,0 degrader is estimated to increase the neutrino whereas reactors produce primarily vc's and high-energy flux by ~40%. accelerators are sources of vu's and vu's. Stopped Jt"'s and stopped u"'s are absorbed so that fe\? u"'s decay. dCalculated for a 15-metric-ton detector using a 20-MeV 3 Thus the ve flux is suppressed by a factor of at least 10 . threshold. The neutrino flux from the beam stop has been determined from a measurement of the rate of stopped- rc+ decays per incident proton in an instrumented copper beam stop.2 Recently this flux has been enhanced by the addition of a 20-cm-thick water degrader just upstream of the isotope-production target and the beam stop. Details concerning this flux are shown in Table I. Protection against backgrounds associated with the beam stop is provided by a 6.3-m-thick iron shield. The iron thickness was chosen to reduce backgrounds from the beam stop to a level below anticipated neutrino signals.3 The large (6%/9%) duty factor at LAMPF poses a severe problem for neutrino experiments in that the rejection factor it provides against cosmic-ray backgrounds is very small compared to that typically avail- AF-rROX. 21.2 m FROM BK3MED able at high-energy accelerators. Furthermore, cosmic- TARGET TO NEUTRINO DETECTOR ray backgrounds are extremely serious at these low SCAIE 0 3? cm - 0 305 m energies. Therefore, the walls and roof of the LAMPF neutrino facility consist of iron 1.0 and 1.5 m thick, Fig. 2. respectively. This iron thickness was chosen to reduce LAMPF beam-stop neutrino facility layout. backgrounds from the hadronic component of the cosmic rays to a level below that arising from the muonic component. Figure 2 shows a schematic of this neutrino facility.

November 1983 LAMPF USERS GROUP PROCEEDINGS 99 Los Alamos National Laboratory Physics Goals l IO F

The large fraction of i/e's from the LAMPF beam stop LAMPF RATES FOR WEINBERG MODEL (NORMALIZED TO V-A) makes it a unique source of neutrinos. This uniqueness is 20-MtV THRESHOLD exploited in the planned experimental program, which 10 focuses on ve physics. WEINBERG The primary goal of Exp. 225 is to study neutrino- TOTAL RATE electron elastic scattering, with particular emphasis on

vee~ —*• vte~. The purely leptonic processes, unfettered by uncertainties associated with hadronic corrections, provide critical testing grounds for theoretical ideas. In the electroweak theory of Weinberg, Salam, and Glashow (WSG), a weak neutral-current interaction arises from Z° exchange. The strength of this interaction 2 is determined by sin 6w, the one new parameter in the theory. In the absence of this weak neutral-current { interaction, there is no Pu,e~ elastic scattering, and the weak charged-current interaction, already given by V-A theory, gives a well-defined {v\,e~ elastic-scattering cross section. With a neutral-current interaction, 'v'^e" elastic scattering exists, and V ,e" elastic scattering is modified by e i6s the addition of the neutral-current diagram in the scatter- 0.0 0.2 0.4 0.6 0.B 1.0 ing amplitude. Because the cross section is proportional X= *in to the square of this amplitude, an interference arises Fig. 3. between the two terms. This interference is well defined, and it is predicted to be destructive by the WSG Rates for neutrino-electron elastic scattering vs 2 electroweak theory.4 This interference between the sin 6w, normalized to V-A, with a 20-MeV charged- and neutral-current weak interaction cannot be threshold. measured anywhere else. Therefore, such a measurement would be a critical and unique test of the WSG Using a long-delayed coincidence capability to tag 12N unification of the electromagnetic and weak interactions. beta decay, we expect to detect the inverse beta reaction The V^e" and vt,e~ elastic-scattering rates from I2 n n on C, that is ve C -*• e~ N<*'. This would be the first WSG, normalized to the V-A rate with a 20-MeV direct observation of a neutrino reaction on a nucleus detection threshold, are shown in Fig. 3. The anticipated other than the deuteron where nuclear effects are rele- rates for Exp. 225, for V-A, and for WSG with 2 vant. sin Gw = 0.23 are shown in Table I. With this rate, we believe that an accurate measurement of the elastic- scattering cross section is possible. Thus we may both Detector System demonstrate the existence and determine the sign of this interference between Z° and W* exchange diagrams. The Exp. 225 detector system occupies the entire accessible volume inside the LAMPF neutrino cave. The With the anticipated suppression of the vt flux from n" and u" absorption in the beam stop down to the level of detector system layout is shown in Fig. 4. An active anticoincidence, consisting of four layers of a multiwire 10~\ an observation of a i>e flux substantially larger than this would imply new physics — for example, from proportional chamber (MWPC), is used to reject charged + + cosmic-ray events with very high efficiency or, in other vu —»- ve oscillations, or u —*• e ve vw as allowed by the 5 multiplicative lepton-number-conservation law. We antic- words, with a net inefficiency of a few times 10~ . Inside ipate a sensitivity to 5M2, assuming maximal neutrino this MWPC is a 13.34-cm-thick iron shield that absorbs mixing, at the level of 0.35 eV2; and to R, the branching neutrals (gammas) generated by muons. The iron shield + + ratio for u -* e ve v,,, at the 1% level. is augmented by an additional 2.54-cm-thick layer of lead on the north wall and on the roof.

100 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory F

swrowcfl—"—~~~—*— *

5 »LMH CM*MBEP «*DOUT A D£T(XTO4 5 V | ? 5 ft 1, N F °0 L u f L T 1 0 R

LIGHT . fT^TTT^TTrTTTT

Fig. 4(a)-(c). Schematics of the Exp. 225 detector system: (a) plan view, (b) elevation view, and (c) end view.

(b)

November 1983 LAMPF USERS GROUP PROCEEDINGS 101 Los Alamos National Laboratory The central target/detector system has a sensitive and after the trigger (top, middle, and bottom, respec- mass of about 15 tons. It contains 40 layers of NE114 tively). plastic scintillator (3.05 m by 3.05 m by 2.54 cm) alter- The MWPC anticoincidence system is shown sur- nated with plastic flash chamber modules (5x and 5j> rounding the plan view of the central detector. The alternating layers/module).5 The scintillation counters MWPCs in the walls are standing on end (vertically), and measure energy as well as dE/dx (particle those in the roof and floor are lying horizontally, identification).6 The flash chamber modules measure orthogonal to the central detector planes. position and angle within each module. Thus the effect of There are four layers of MWPCs in the walls and roof multiple scattering, which broadens the kinematic for- and one layer in the floor. The roof and floor MWPCs ward cone (<10°) of the scattered electron in v,e~ are shown above and below the plan view, respectively. scattering, is minimized. The filled-in boxes represent MWPCs in coincidence To identify cosmic-ray backgrounds, activity in each with the event in the central detector; those with crosses, of the 600 MWPCs and in each of the 160 scintillation a few microseconds earlier; and the open boxes, up to counters is stored for 32 us before a trigger with a time 32 us earlier. resolution of 400 ns. The time duration is dictated by the muon lifetime and by the anticipated cosmic-ray 1 stopped-muon decay rate of about 10'day" . Cosmic-Ray Rates n To identify the inverse beta reaction, ve C 1 1 —> e~ "N * , activity in each of the 160 scintillation About 5000 charged cosmic-ray particles traverse the counters is stored for 64 ms after a trigger with a time MWPC anticoincidence system per second. Of these, resolution of 16 us. The time duration is dictated by the some 1300 s"1 can generate triggers in the central 12 7 11-ms half-life of N; its anticipated rate is also shown sandwich detector. The on-line energy spectrum of these in Table I. events, with the scintillation counters tuned for large The detector system has been in full operation for the energy deposition events (proton tune), is shown in past few months. Data have been collected for LAMPF Fig. 6. This spectrum is labeled Tt (triple coincidence T, cycle 38, and data collection likely will continue for the with only a lower threshold per scintillator at about next couple of years. Our earlier difficulties with opera- 2 MeV, that is, integral mode /). tion of the vertical tubes in the flash chamber modules Application of a short (1.2-us) anticoincidence block, have been resolved, and the efficiency is now consider- 1 T, • As, reduces the trigger rate to about 20 s" . These ably improved. are generated primarily by stopped-muon decays, as can Examples of various events selected from our on-line be seen in the energy spectrum in Fig. 6 and in the computer display are shown in Fig. 5 and include (a) a pretrigger time distribution in Fig. 7. penetrating muon, (b) a stopped muon decay, (c) an Increasing the anticoincidence duration to 20 jis, 1 interacting neutron, (d) a high-energy electromagnetic T,-Ap, reduces the trigger rate to about Is" . The shower, and (e) an elastic-scattering candidate. The left majority of these are due to neutrons. If, in addition, one half of each figure shows the plan view and the right half applies an upper threshold per scintillator of about shows the elevation view with the detector bottom on the 20 MeV—that is, differential mode, TD-Ap—the re- right. The beam stop—that is, the neutrino source (at the sidual trigger rate becomes 0.2 s~K Thus the combina- top of the figure)—is located about 7 m from the tion of a 20-u.s anticoincidence duration and a 20-MeV detector. upper limit on energy deposition per scintillator reduces 4 The central box i.L the plan view outlines the sandwich cosmic-ray trigger rates by a factor of ~10 . detector. The horizontal lines in this box represent pulse With the scintillation counters tuned for low-energy heights in the corresponding scintillation counters. The deposition events (electron tune), the TD • Av trigger rate 160 counters are arranged in 40 planes of 4 counters is about 0.10 s"1. This trigger rate translates to about each. The 40 flash chamber modules are alternated with 800 events per day with 9% beam'ON duty factor. The the scintillation planes. The output from the vertical flash corrected scintillator energy spectrum for these events is tubes are shown on the left and the horizontal tubes are shown in Fig. 8 (total energy deposited in the detector is shown on the right. The three small boxes on the far right about 1.6 times that deposited in the scintillator). Most of show activity in the scintillation counters bjfore, during, these are from charged particles traversing the sandwich

102 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory POT'S ».U71E»29 POT'S 1.40012 i LTBOFT: •.•£•: 3» LTMFF: *: 0: • LTMN : •: •: • r— LT1O-I : •: 4:1" m 5"

- jF BEAM WAS OFF BEAM WAS ON TOTAL EMRGY < 33B HEV TOTAL DCFCY • 3«7 EVENT WW! i 183 EVEHT NUWER = 133 • MFC RATE i S864.B MJPC RATE = E719.9 1 SS 1:26:41 SHORT BLOCK a. 7/-B3 19:43:14 (a) (d)

POT'S O.307BE+2: POT'S LTBCFF: 2:E9:19 LTBOFF: LTBCN : 3:31: a LTJON : ..TPI'G (WE. 9.aes TSia AVE. TRIG LA?T 13.^ TRIG LAST

BEAM WAS OFF BEAM WAS ON TOTAL E>€RGV = 12 ICV EVENT W*«ES = 1Z37 TOTN. E>€BGT * Hf>C RATE EVEHT NUWER * «J=C RATE 9 (b) (e)

POT'S 9.718 LTBOFF: B:Z7:Z LTBOH : 9: Z:5 TRIG fl«E. 8.73» TRIO LOST 33~" Fig. 5(a)-(e). Selected events in detector from the on-line display: (a) traversal cosmic-ray muon, (b) stopped cosmic- ray muon decay, (c) cosmic-ray neutron interaction, (d) high-energy cosmic-ray electromagnetic shower, and (e) elastic-scattering candidate.

BEAM WAS OFF TOTAL ENERGY > B t£V EVENT HJHtK - 2m rfC RATE - G791.3 3/ «-« 6:37:12 (c)

November 1983 LAMPF USERS GROUP PROCEEDINGS 103 los Alamos National Laboratory 10 detector (anti-inefficiency, neutrals converting in the T, (!3T0/») gamma shield); neutrons interacting in the detector (producing the decay chain n —*• u —»• e); stopped cosmic-ray muons (decaying after 20 us); etc. Removing 10 these and focusing on low-energy (£40 MeV deposited in the scintillators) single-track events within the fiducial volume, the residual rate is about 7% of the TD • Ap rate. This spectrum also is shown in Fig. 8. PROTON TUNE Applying tighter constraints on these single-track events (single track in both views, cleaning up thresholds, dEldx cuts, energy deposition in a contiguous group of scintillators), the event rate drops, by another factor of 6, to 9 day"1 with 9% duty factor. An angle cut of 20° 10 1 1 CO (16°) reduces this rate to 1.3 day" (0.8 day" ) with 9% N. (0 duty factor. The energy spectra of these events also are I- shown in Fig. 8. The anticipated rate for neutrino-electron elastic scat- O 10.-"2 1 TjAp (0.98/S) tering is estimated to be about 1 day" after the cor- P ''-si responding cuts are implemented—for example, fiducial volume, dEldx, and tracking inefficiency. In this way cosmic-ray backgrounds are reduced to the level of the .-3 10 anticipated elastic-scattering signal.

Td-Ap{l/5O

Beam-Associated Rates 10{•*, 100 200 300 ENERGY (MeV) The trigger rate with beam (7"D • Ap • BG) is measured to be about 12(mA-h)"!. The corrected scintillator Fig. 6. energy spectrum is shown in Fig. 9. After imposing On-line cosmic-ray spectra with scintillators tuned additional requirements as for the cosmic-ray events, the for large energy deposition events (proton tune). corresponding two spectra are also shown in Fig. 9. Estimated energy loss in the flash chamber mod- These rates are about 2 and 0.3 (mA-h)"1, respectively. ules is included here.

Fig. 7. The on-line time distribution of scintillation activity before TD -As triggers. The muon lifetime is evident.

i DW'l. evr -i»™ a NO xm£ RUN i 17-Mus-az m- a. WR* a. Bi 1 CORE TST e 22:»t:22 SU*= 3381. INK a. ADO=

104 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory BEAM-ASSOCIATED EVENTS COSMIC-RAY RATES ELECTRON TUNE ELECTRON TUNE 10 10 z CD V. CO t- i^3200 i 150 EVENTS 10 •,000/day z 10' «00/9% doy) 111 00 > UJ u. 532 i4l EVENTS I o W oc 10 UJ I- m REQUIRE SINGLE TRACK -754 16 EVENTS o o

10 .0"'

WITHIN FORWARD 20 ANGLE 14/DAY (I.S/»% OAY) -I 10 15 30 45 60 75 90 105 15 30 45 60 75 90

SCINTILLATOR ESCINTILLATOR

Fig. 8. Fig. 9. Scintillation spectra of cosmic-ray events in milli- Scintillation spectra of beam-associated events in electron volts. Energy loss in the flash chamber milli-electron volts. Energy loss in the flash modules is not included (the total energy is esti- chamber modules is not included (the total energy is mated to be about 1.6 times the energy deposited in estimated to be about 1.6 times the energy de- the scintillator). Cuts used to reject backgrounds posited in the scintillator). Cuts used to reject are described in the text. backgrounds are described in the text.

The reduction factors for the beam-associated events are The anticipated v,e~ scattering rate of 1.8 per day in 2 not as large as those for cosmic rays, presumably because Table I, assuming WSG with sin 9w = 0.23, is reduced neutrino events are being detected. substantially when considerations such as (1) accelerator The cos 6 distribution of both the beam ON and beam operating efficiency (0.85), (2) detector operating effi- OFF events, passing all the above cuts, is shown in ciency (0.85), (3) anticoincidence deadtime effects (0.85), Fig. 10, where 9 is the electron track angle relative to the and (4) on-line computer deadtime effects (0.85) are direction from the beam stop. The beam OFF distribu- included. These factors produce an event rate written to tion is shown normalized to our beam ON live time from tape of less than 1 pier calendar day. the 6 weeks of running during LAMPF cycle 38. The The detection rate after analysis of data suffers from beam ON minus beam OFF difference is small but the application of cuts on the data such as (1) fiducial consistent with expectations, given the preliminary volume (0.80), (2) tracking efficiency, (3) dE/dx require- nature of this analysis and the large statistical uncertain- ments, and (4) energy deposition in a contiguous group ties. The two forward cos 9 bins (9 < 16°) contain of scintillators. These combine to give a net detection 19 ± 6 events, of which some number of background rate of less than 0.5 per calendar day. events, both neutrino induced and neutron induced, must be expected in addition to the v,e~ events.

November 1983 LAMPF USERS GROUP PROCEEDINGS 105 Los Alamos National Laboratory to our goals, and spurs us to continue the efforts that are NUMBER OF EVENTS necessary to get there. VI COS • 20 BEAM-ASSOCIATED EVENTS Acknowledgments

z m This experiment has received much support from both 05 COSMIC-RAY EVENTS the University of California at Irvine and the Los IS T Alamos National Laboratory. We thank M. Bander, J. Browne, G. Keyworth, F. Reines, L. Rosen, and many others at both institutions for their efforts on our behalf. The enthusiastic and able contributions of our technical support personnel, especially N. Colbert, C. Dalton, W. Johnson, Q. Jones, G. Krausse, C. Lindsay, M. Osborn, and J. Sena, have been and continue to be critical for the successful operation of this detector system. The steady beam available at the beam stop is a tribute to the LAMPF accelerator operations group and the LAMPF experimental areas group. This project is supported by the United States Depart- ment of Energy and by the National Science Foundation. 1.00 0.90 0.80 0.70 cos e REFERENCES Fig. 10. The cos 9 distribution of events, where 0 is the 1. LAMPF Users Handbook, Los Alamos National electron track angle relative to the direction from Laboratory document MP-D0-1-UHB (Rev.), the beam stop. Beam OFF data are normalized to Sec. 6B (December 1980). our beam ON data from LAMPF cycle 38. 2. H. H. Chen, J. F. Lathrop, R. Newman, and J. C. Evans, Nud. Instrum. Methods 160, 393 (1979). Conclusions 3. G. A. Brooks, H. H. Chen, and J. F. Lathrop, The combination of an extremely small cross section Neutrino '77 (1978), Voi. 2, p. 376; see also the (low data rate) and a potentially high cosmic-ray back- University of California at Irvine report UCI-Neu- ground rate makes the neutrino-electron elastic-scatter- trino No. 19(1977). ing reaction a very difficult process to study. The observed signal and background rates are encouraging 4. B. Kayser, E. Fischbach, S. P. Rosen, and H. from the standpoint of detection, although both can and Spivack, Phys. Rev. D 20, 87 (1979). should be improved, and we are working in this direction. For example, the on-line computer deadtime effects have 5. R. C. Allen, G. A. Brooks, and H. H. Chen, IEEE been reduced for cycle 39 data (the corresponding live- Trans. Nucl. Sci. NS-28, 487 (1981). time factor is now 0.95 instead of 0.85), and the collected data are being used to locate the weaknesses in our 6. K. C. Wang and H. H. Chen, IEEE Trans. Nucl. Sci. cosmic-ray shields (a factor of 2 or more improvement NS-28, 405 (1981). appears possible if these leaks can be plugged). The progress that has been made has brought us much closer 7. T. W. Donnelly, AIP Conf. Proc. 26, 454 (1975).

106 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory SIMPLE FEATURES OF (pn~) REACTIONS NEAR THRESHOLD

Steven Vigdor Indiana University

Steven Vigdor

(Note: Paper not available for publication.

November 1983 LAMPF USERS GROUP PROCEEDINGS 107 Los Alamos National Laboratory WORKING GROUP MEETINGS

ENERGETIC PION CHANNEL AND voted unanimously to recommend that MP-10 acquire a SPECTROMETER (EPICS) WORKING GROUP new technician because of the large amount of work involved at EPICS and HRS with complicated projects Susan Seestrom-Morris, Chairman such as back-angle scattering, double charge exchange, polarized targets, and, in the near future, the LEP R. Boudrie delivered the status report. Because a new spectrometer. aluminum target box is being designed, now is the time to make it known if EPICS users are interested in a larger ATTENDEES aluminum target. The group unanimously voted to Los Alamos National Laboratory express the Users' wish that a larger target be installed if James F. Amann at all possible. A majority of experiments on EPICS Richard L. Boudrie currently are beam-limited. Andrew Browman J. Amann reported on the implementation of the T. K. Li RSX-HM Q system at EPICS and its imminent avail- Christopher L. Morris ability on the VAXes. He estimates VAX replay to be 3.5 times faster than the PDP-11/45, and PDP-11/70 Other Institutions Peter W. F. Alons, University of Colorado replay to be 2.5 times faster. George R. Burleson, New Mexico State University The group unanimously recommended G. Burleson Edward F. Gibson, California State University, for the Technical Advisory Panel, and B. Zeidman and Sacramento B. Bayman for appointment to the Program Advisory C. Fred Moore, University of Texas Committee. W. Ccitingame was unanimously elected Susan Seestrom-Morris, University of Minnesota new Chairman. Benjamin Zeidman, Argonne National Laboratory The group commented on the tremendous support of the Group MP-10 staff, especially the technicians, and

SOLID-STATE PHYSICS AND MATERIALS ment in the new facility. A complete report on this work SCIENCE WORKING GROUP is available.1 To better understand the available radiation environ- Walter F. Sommer, Jr., Chairman ment, a threshold foil experiment has been designed and built. The radiation will be completed by the winter of W. Sommer reported progress on the upgrade of the 1984, and results will be compared to calculation. LAMPF beam-stop area that includes new facilities for M. Wechsler addressed the applicability of the new experimentation in nuclear physics and chemistry, LAMPF facility to radiation-effects studies in general. atomic physics, and radiation-damage effects. The basic He emphasized the large available volume (2401 in the philosophy has remained constant over the past year. neutron-irradiation area). In summary, the LAMPF Experiments can be placed into the direct proton beam facility provides a large experimental volume relative to or in the spallation neutron flux on the bottom of vertical other available and planned neutron-irradiation facilities shield plugs; services and instrumentation are routed up at a moderate neutron flux (~6 x 1013 cm ~2 s~'). In the through these plugs into an accessible area for on-line direct proton beam, the flux is higher by about 10 times, control and monitoring. Funds for the work have been and here the facility is unique, especially for the study of established, and the facility is scheduled for completion accelerator materials. For the neutron-irradiation area, in the spring of 1985. he introduced to this group a new figure of merit, dpa D. Davidson described her work on Monte Carlo- -,6/FPY (displacements per atom times liters of volume based calculations that estimate the radiation environ- per full power year), and compared" the facility, in

108 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory operation and planning, to others. The comparison that are candidates for structural material for the Ger- follows. man SNQ target station. Two alloys at two tempers each, along with some of Lundberg's molybdenum/- Facility dpa -J/FPY rhenium alloys, will be irradiated for 9 weeks beginning in late November 1983. Included also is ultra-high-purity INTOR (proposed)" 182 aluminum material that will receive about 0.5 dpa. The TASKA (proposed)8 1510 goal here is to compare void-density measurements as FMIT (design)8 5 deduced by position annihilation methods to those RTNS-II (in operation)" 0.0003 measured by transmission electron microscopy. Lawrence Livermore J. Cost, J. Stanley, Brown, and Hansen have been TASKA-M (proposed)8 550 studying the degradation of magnetic properties in LAMPF (design, construction)15 88 Mumetal as compared to amorphous alloys in an attempt to improve the lifetime of toroids that are used aReference 2. currently as monitors at LAMPF. M. Wechsler, private communication, November 1983. F. Clinard questioned the stability of the neutron spectrum in view of the variable isotope production target inventory. The extent of this variation has not yet Wechsler, Sommer, and Davidson, along with L. been measured, but since a threshold detector experiment Greenwood of Argonne National Laboratory, are ad- will be included with each neutron-irradiation experi- dressing the contribution of the "high-energy tail" in the ment, the final total fluence and spectrum will be known. spallation neutron spectrum to damage parameters, A second question concerned the secondary particle flux PKA spectrum and average PKA^, so that comparison (especially protons) that would also be incident on can be made to fission neutron-irradiation data as well as specimens in the neutron-irradiation ports. It was pointed the environment anticipated for fusion reactor materials. out that proper design can shield the experiments from A. Harvey asked about the existence of high-energy the secondary protons. neutrons at the LAMPF beam stop. To date, no M. Wechsler was nominated as a representative from experimental verification has been reported, although this working group to the Technical Advisory Panel. some attempts at measurements have been made. Harvey agreed to sort out the experimental work that W. Sommer was re-elected chairman for the next year. has been done. REFERENCES W. Talbert reported on his work on identifying short half-life isotopes produced by 800-MeV protons. In the 1. D. Davidson et al., "Calculated Radiation Environ- system planned for the LAMPF beam-stop area, a ment at a Proposed New Irradiation Facility at helium-gas jet will transport isotopes that have attached LAMPF," Los Alamos National Laboratory docu- to aerosol particles in a mass separator in a time frame of ment LA-UR-83-33 (January 1983). 300 ms. The high current at LAMPF is an advantage for 2. G. L. Kulcinski et al., "TASKA-M, A Compact this work. Fusion Technology Test Facility," presented at the L. Lundberg noted his interest in studying molyb- Third Topical Meeting on Fusion Reactor Materials, denum/rhenium alloys in the neutron flux as a possible Albuquerque, New Mexico, September 1983. material for core heat pipes for the SP100 SNAP system. This high-temperature alloiy exhibits acceptable ductility, ATTENDEES and the desire is to learn about radiation effects on ductility. Los Alamos National Laboratory C. Hansen reported on his work with R. Brown and Frank W. Clinard Lynn B. Lundberg others on a study of radiation effects on permanent Jay H. Cook Don M. Parkin magnet samarium/cobalt material. An in situ test to James R. Cost R. C. Potter determine field strength as a function of neutron fluence Dorothy R. Davidson Robert C. Reedy has been designed and built, and will be installed during David J. Farnum Walter F. Somrner the winter LAMPF run cycle. Calvin F. Hansen J. Stanley Alexander Harvey Willard L. Talbert W. Sommer described an experiment that uses an Michael E. Lazarus Monroe S. Wechsler isotope production stringer to study aluminum alloys

November 1983 LAMPF USERS GROUP PROCEEDINGS 109 Los Alamos National Laboratory NUCLEON PHYSICS LABORATORY (NPL)/ demand for the 120-Hz low-energy option is rather POLARIZED FACILITIES limited. WORKING GROUP The working group heard that a P~ buncher is not likely to be built for the present Lamb-shift source Olin van Dyck and Michael McNaughton, Chairmen because of its anticipated replacement. Several members said that availability of a bunched or chopped beam is Possible new interest in the Area BR neutron beam important for many neutron experiments, so this capabil- was expressed. The University of Colorado/Los Alamos ity should be a significant design constraint on the new collaboration in Line D has been studying the (p,n) P~ source. reaction with long flight paths on both p and n; D. Lind T. Bhatia was elected NPL/Polarized Working Group reports that neutron production from 7Li at 0° produces Chairman for 1984. The HRS representatives said that an ~1 -MeV-wide energy spike, much narrower than from the combined NPL/Polarized meeting was an adequate 2H and narrow enough to be useful as a beam for a great forum for their interest in polarized beam matters. deal of (n,p) nuclear physics. Since variable energy is wanted, a move from Line D to Area BR is desirable. A ATTENDEES high value of spin transfer in this reaction would be a Los Alamos National Laboratory great bonus, but apparently we don't know this number Edwin P. Chamberlin 7 yet. The possibility of Li as a good neutron-production Kevin W. Jones target in Line B might affect LAMPF plans for an John J. Krisch upgrade of the present LD2 target. Design of a medium- Joseph L. McKibben resolution spectrometer (MRS) for (n,p) has been Michael McNaughton sketched in Proposal 823; it would use pool magnets. Thomas M. Putnam Group MP-10 also has considered use of an MRS in Richard R. Silbar NPL as an augmentation for medium-resolution nuclear James E. Simmons Ralph R. Stevens, Jr. physics, such as polarized-target experiments, where the Olin B. van Dyck full capacity of the High Resolution Spectrometer (HRS) is not exploited. Other Institutions Nuclear physics with (n,p) also will require improved Tarlochan S. Bhatia, Texas A&M University/Los Alamos technology for monitoring the primary beam E and AE; Charles Glashausser, Rutgers University this technology is being developed by both the Colorado Carol Harvey, University of New Mexico group and the Proton Storage Ring (PSR) team. John C. Hiebert, Texas A&M University Other entries on the demand side of the ledger are the Charles L. Hollas, University of Texas Bugg aad Igo proposals employing polarized targets in Alan Krisch, University of Michigan Catherine C. LeLuc. University of Geneva the External,Proton Beam (EPB). David Lind, University of Colorado The working group discussed preference for two ways Bill W. Mayes II, University of Houston of slicing the low-energy (3%) beam Juty factor: either 40 Murray Moinester, Tel Aviv University Hz with full beam-gate width, or 120 Hz with one-third Gordon S. Mutchler, Rice University beam-gate width. It appears that the experiments without L. C. Northcliffe, Texas A&M University buffered electronics are helped by higher macropulse Gianni Pauletta, University of California, Los Angeles rates. Experiments with buffered electronics, found in Charles F. Perdrisat, College of William and Mary HRS and the EPB Case-Western Reserve University Gerry Phillips, Rice University trailer, are not strongly affected by duty factor slicing. Lawrence Pinsky, University of Houston The photodetachment experiment is planning to use a Glen A. Rebka, Jr., University of Wyoming 120-Hz Excimer laser that permits use of low-energy Peter Riley, University of Texas John UUmann, University of Colorado beam, preferably at 120 Hz. The Area BR neutron users (regrettably) do not often have trigger rates high enough for 40 or 120 Hz to make a difference; therefore, the

110 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory MUON-SPIN-ROTATION M. Leon emphasized that for nSR experiments, a WORKING GROUP higher duty factor is more important than muon beam intensity. This will be reiterated to L. Agnew. Carolus Boekema, Chairman S. Dodds was unanimously recommended as candidate for the Technical Advisory Panel, and A. Denison Following introductory remarks and discussion of the was elected chairman of the working group for 1984. minutes of the last meeting, it was noted that the resource paper on uSR facilities and programs in the United States ATTENDEES produced by a National Research Council Committee is Los Alamos National Laboratory in press. The USDOE pulsed-muon facility proposal and D. Wayne Cooke its deferral for 1 year were discussed at some length. Richard L. Hutson Without doubt, there is a need for a pulsed-muon facility Melvin Leon at LAMPF, tentatively planned to start operation in 1988 when funds are available. Other Institutions Short reports were then presented on the 3He/4He Carolus Boekema, Texas Tech University refrigerator, the chopped-muon beam experiment, and Roger L. Lichti, Texas Tech University the active and pending (xSR proposals.

LOW-ENERGY PION (LEP) CHANNEL was measured at different channel momentum bites. The WORKING GROUP Wharton tune was noticeably better only at a momentum bite of Ap/p= 0.1%. There was also some evidence for a Michael J. Leitch, Chairman-Elect dependence of the channel flux on beam tune, although this was not carefully studied. M. Leitch was selected by the working group as The other major finding was that the standard Chairman for next year; the working group also selected TRACE tune gives a beam at the correct height but Leitch for nomination to the Technical Advisory Panel. 0.5-i.O cm to the left relative to the beam-line mark on New front jaws are in and working well. Next spring, the new 2.56-cm-steel LEP floor. Fitzgerald intends to Ql and Q2 will be replaced along with another set of establish a permanent set of monuments in the LEP cave new CL1 and CL2 jaws. The channel vacuum is much so that experimenters can have alignment marks that are improved. A PDP-11/44 has replaced the old not moved or altered. Also, when using the MP-13 phase- PDP-11/45 that gave so many problems in the past. It space detector gear, the beam waist is typically located as was initially installed for a coincidence experiment that much as 75 cm in Z away from the TRACE-predicted needed more histogram space, but it is likely that it will position. remain permanently. It was noted that EPICS is asking that the aluminum- production target be increased to 6 cm from its present length of 3 cm. This would increase the LEP horizontal LEP Channel Status (D. Fitzgerald) source size by a factor of 2, resulting in a larger horizontal beam size. An extensive series of development studies has been Finally, it was agreed by the working group that a carried out recently by Group MP-13. One objective was removable collimator at the front of the LEP channel to investigate the properties of the so-called Wharton was necessary. tune. Carnegie-Mellon University found that this tune gives an improved energy resolution; it is identical to the TRACE tune except that Ql and Q2 are set about 5% Clamshell Spectrometer (R. Boudrie) lower. In the MP-13 studies, spallation products from the production target (d, a, and 3He) at 128 MeV/c were The new low-energy pion spectrometer (Clamshell) observed in solid-state counters, and the energy spread should be operational by June 1984. The iron and the

November 1983 LAMPF USERS GROUP PROCEEDINGS 111 Los Alamos National Laboratory vacuum chamber are on site and assembled. The coils than normal absorber at the center of the channel, the also are here at the Equipment Test Laboratory (ETL) differential energy loss between pions and electrons is and soon will be assembled with the iron at ETL. A enough to separate them substantially at the end of the scattering chamber is designed and out for bids, expected channel. The electrons then can be removed with a to be ~$40 thousand. It has a four-target paddle-type catcher slit. According to calculations, this reduces the target mechanism and a sliding seal between the scatter- nominal e+/n+ ratio of ~20-100 to less than 2%. It was ing chamber and the magnet. The magnet field clamp suggested that development time be used to see whether design will be a two- to three-iteration procedure because this is realized for the real channel. the problem is too complicated to model well. Recent tests at EPICS have proved that the Group MP-10 delay- ATTENDEES line drift chamber works well for an inclined focal plane, Los Alamos National Laboratory as will be the case with the Clamshell. A resolution of Richard L. Boudrie =;200 urn was achieved and the left/right ambiguity was Huan-Ching Chiang resolved. Virginia Polytechnic Institute will be responsi- Dan Fitzgerald ble for building the multiwire proportional chambers Earl Hoffman (MWPCs). There will be a low-energy pion physics Michael J. Leitch workshop just before the Program Advisory Committee Richard D. Werbeck meeting in January. Other Institutions Kazuo Gotow, Virginia Polytechnic Institute Harold E. Jackson, Argonne National Laboratory Very Low Energy Pions (K. Gotow) R. J. Peterson, University of Colorado Barry M. Preedom, University of South Carolina Several new experiments are planned that need clean Robert P. Redwine, Massachusetts Institute of Technology pion beams with energies between 5 and 15MeV. Barry G. Ritchie, University of Maryland REVMOC calculations indicate that by using a thicker

NUCLEAR CHEMISTRY WORKING GROUP data during cycles 39-41 to conclude this experiment, with particular emphasis directed toward measuring the Jan M. Wouters, Chairman masses of 20N and 24F. Several theoretical models indicate that these highly neutron-rich nuclei should be Y. Ohkubo was elected working group chairman for susceptible to deformation, which would be expected to 1984. The working group then nominated R. Korteling change the binding-energy trends of these nuclei. from Simon Fraser University to serve on the LAMPF G. Giesler reported on Exp. 728, "Study of Pion Technical Advisory Panel for a 3-year term. His appoint- Charge-Exchange Mechanisms by Means of Activation ment, which must be approved by the LAMPF Board of Techniques." He described an attempt to measure the Directors, will continue the representation of the nuclear single-charge-exchange cross sections at various energies chemistry community on this important committee. for the reactions "B(7C+,JI°)"C, 11B(n-,n°)llBe, C. Pillai, a graduate student from Oregon State 23Na(;i+,n0)23Mg, and 23Na(7r,;i0)23Ne. Data obtained University working with the Thin Target group, for the pion on sodium reactions are being ana- presented an update on phase II of Exp. 308, "An lyzed, with careful attention to possible sources of Attempt to Make Atomic Mass Measurements in the background such as secondary neutron reactions. Initial Thin Target Area." This experiment hopes to perform results indicate that the data exhibit a cross section vs direct mass measurements using a combined total energy target-thickness dependence that is contrary to previous and time-of-flight technique. To carry out this research, a results. However, Giesler cautioned that not all sources new gas ionization detector has been developed with an of background have been fully corrected for and that the energy resolution of 0.5% and a Z resolution of 3.1% at analysis is in very preliminary stages. a Z of 10. The Thin Target group plans to collect mass

112 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory R. Bhalerao, a visitor from India in the Group INC-11 charge exchange and the quantum mechanical inter- pion theory section, described the method being used to ference between the charge-exchange mechanism and the model the (n,2n) reaction on nuclei. To begin with, they qur.si-free scattering mechanism for I2C), and pion in- are doing numerical calculations of the JIW—>- nnN elastic scattering followed by single-nucleon evaporation reaction and comparing their results with data near for 48Ca. threshold and at higher energies (200 MeV to several GeV). The second step involves understanding the (n,nn) ATTENDEES reaction on the simplest nucleus (namely the Los Alamos National Laboratory nD —*• nnNN reaction) for which the theory has been R. S. Bhalerao Lon-Chang Liu worked out. The final phase is understanding of the Merle E. Bunker Yoshitaki Ohkubo (n,mi) reaction involving a general multinucleon system. Gilbert Butler Charles Orth This work will be complicated because of all the Bruce J. Dropesky James E. Sattizahn additional reaction pathways that will have to be in- Peggy Dyer David J. Vieira cluded beyond those already included for the deuteron Gregg Giesler Jan M. Wouters reaction. Darleane C. Hoffman Shu-Heng Yan Ohkubo summarized the results and calculations from Jutta Kunz Exp. 595, "A Study of Pion-Induced Single-Nucleon- Other Institutions Removal Reactions in 12C and 4!lCa." The goal of this Daeg S. Brenner, Clark University study is to reconcile the discrepancies between theory Ralph Korteling, Simon Fraser University and experiment for the cross-section ratios a(n~)/a(n+) in R. H. Kraus, Jr., Oregon State University neutron-removal reactions, and o(ji+)/o(7i~) in proton- Chandra Pillai, Oregon State University removal reactions. Ohkubo explained that the reactions James J. Reidy, University of Mississippi proceed dominantly through the quasi-free scattering Sayed H. Rokni, Utah State University mechanism (which is complicated by final-state nucieon Kamran Vaziri, Utah State University/Los Alamos

HIGH-RESOLUTION SPECTROMETER (HRS) now measured, and the instrument has been calibrated WORKING GROUP and shown to operate well. All components for the insertable Faraday cup have Kevin Jones, Chairman been acquired, and final assembly and testing are being planned. Work on the focal-plane shielding is continuing. The HRS facility report was presented by K. Jones. Design and loading studies have been finalized and The HRS continues to operate well and reliably; no construction and installation will be arranged in the near major changes have been made to the focal-plane future. We hope that the frame and base, at least, will be detection system in the last year. A high-resolution run at installed before cycle 41 in the summer of 1984.

333 MeV was accomplished successfully in cycle 37, The dual-flask LH2 and LD2 target is now operational, attaining an overall resolution of 40 keV. but some heat-leak problems that cause boiling of the Advances have been made in Line C instrumentation targets must be solved before cross-section measure- that facilitate beam tuning. Notably, the insertable-strip ments are possible. ion chambers (ISICs) that now exist on all Line C J. Amann reported on the status of the HRS com- televisions have been operated from the 160-fA to puters. The RSX-11M will be implemented at the several-nA level, and aid in reliable and reproducible beginning of cycle 40, and replay on the VAX machines beam tuning. It is planned to add two-dimensional will follow shortly. Thereafter, work will proceed on capability in the scattering chamber. The LineC implementing the array processor versions of acquisi- polarimeter has been upgraded to include 16 counters to tion and replay. It is hoped that the transition will be conform with the Line B and External Proton Beam smooth. Users are notified that customized software configurations. Considerably lower accidental rates are conversion will be the responsibility of the user.

November 1983 LAMPF USERS GROUP PROCEEDINGS 113 Los Alamos National Laboratory S. Greene reported on the Polarized Target Facility. A ATTENDEES successful JV-type run was conducted during cycle 38, Los Alamos National Laboratory and plans for installation of an L-type target during James F. Amann cycle 41 are well under way. ^ Richard L. Boudrie G. Hoffman and C. Whitten were nominated as can- Steven J. Greene didates for the LAMPF Technical Advisory Panel. Sug- Kevin W. Jones gested as replacement candidates for the HRS Program Olin B. van Dyck Advisory Committee were G. Bertsch, G. Crawley, and Other Institutions J. Shepard. Bjarne Aas, University of California, Los Angeles M. Gazzaly was nominated and unamimously elected Andrew Bacher, University of Indiana as the new Chairman of the HRS Working Group. M. Gazzaly, University of Minnesota Jones reported on the development of a Low-Energy Charles Glashausser, Rutgers University Polarimeter for use in the injector region. Approval has Norton Hintz, University of Minnesota . been obtained from LAMPF to continue development of George Igo, University of California, Los Angeles this device under the auspices of J. McClelland. Further D. Lopiano, University of California, Los Angeles development is expected to take place in February 1984. John A. McGill, Rutgers University The possibility of developing a medium-resolution Yugi Ohashi, University of California, Los Angeles spectrometer suitable for use in Area B was discussed. It Gianni Pauletta, University of California, Los Angeles was felt that a significant fraction of the HRS queue Susan Seestrom-Morris, University of Minnesota could be transferred to such a device, especially experiments of the nucleon-nucleon class. The feasibility of such a device will be considered by MP-10.

3 HIGH ENERGY PION (P3) CHANNEL Werbeck added that future plans for the P channel WORKING GROUP include the rebuilding of MS02. E. Hoffman reported on the computing aspects of the Jon Engelage, Chairman P3 channel. • Winchester drives have been installed in both the The working group first elected J. Engelage as the new P3-West and P3-East counting houses (eventually chairperson, and second, nominated W. Briscoe as a Group MP-1 will no longer support removable candidate for the Technical Advisory Panel (TAP). disks). With administrative matters settled, D. Fitzgerald • MP-1 will be supplying less software support in the spoke on channel improvements since the 1982 Users future because of the lack of manpower and Meeting, as well as on present conditions of the P3 because of higher priority items. Specifically, Q channel. support on RSX-1 ID will cease after July 1984. • The front-end quad doublet, QD01 and QD02, and • The installation of terminals to the VAX in the its associated jaws, MS01, were installed. counting house, discussed at the 1982 Users Meet- • A new A-2 target cell, complete with a 6-cm target, ing, has not been implemented. However, cabling to was installed. the VAX in the area and connections to the • The shorted windings in BM03 have been cor- counting houses could be made for a minimal cost. rected. Users therefore should reduce previous Need for such connections should be com- shunt settings by 18%.! municated to the LEEP committee chairman. • The collimating jaws, burned by the beam in late P. Gram. August, are not usable at this time. At this point, D.

114 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Considerable time was spent discussing Users' con- ATTENDEES cerns over the condition of the large-aperture spectrometer (LAS) and the overall running of LAMPF. Los Alamos National Laboratory B. Zeidman and H. Jackson of Argonne National Labo- Donald R. F. Cochran Dan Fitzgerald ratory both expressed deep concern over the mainten- Earl Hoffman ance and calibration of the LAS, citing loss of beam time Michael J. Leitch and difficulties with track reconstruction. A resolution Nelson Stein was drafted requesting additional manpower for Group Richard D. Werbeck MP-10 to cover adequate maintenance and repair of the wire chambers incorporated in the LAS. A second Other Institutions resolution by B. Nefkens, requesting that LAMPF run at Jon Engelage, University of California, Los Angeles appreciably higher duty factors for coincidence experi- Harold E. Jackson, Jr., Argonne National Laboratory ments, was also drafted and unanimously approved. George Kim, University of California, Los Angeles Ali Mokhtari, University of California, Los Angeles Finally, J. Engelage inquired as to the need for a Gordon S. Mutchler, Rice University computer network (for example, DECnet and BITnet) Ben Nefkens, University of California, Los Angeles linking LAMPF to other national laboratories and Charles F. Perdrisat, William and Mary College universities. The idea met with mild approval. Glen A. P.ebka, Jr., University of Wyoming Benjamin Zeidman, Argonne National Laboratory REFERENCE 1. "Proceedings of the Sixteenth LAMPF Users Group Meeting," Los Alamos National Laboratory report LA-9767-C (1983), p. 95.

STOPPED MUON CHANNEL (SMC) provements in the way the machine is run emphasize WORKING GROUP longer duty factors over higher peak currents. They also request that the beam-usage charge rate reflect the duty Gary Hogan, Chairman factor. G. Sanders was nominated for the Technical Advisory L. Agnew reviewed the status of the SMC. In the last Panel, and F. Mariam was elected as the next SMC year, the old counting house hr.s been removed and the Working Group Chairman. cave area expanded. New quadrupole magnets and electromagnetic separators have been installed, and the ATTENDEES low-current controls for the magnets have been im- Los Alamos National Laboratory proved. Lewis Agnew The beam-usage charge rate has been increased from Cyrus M. Hoffman 75 to 85%. Expected future usage is 50% for the Crystal Mel Leon Box, 25% for uSR, and 25% for others. The current Fesseha G. Mariam experimental backlog was reviewed. Gary H. Sanders The group expressed the strong and unanimous opin- Urs Sennhauser ion that the current experiments in the SMC and Biomed E. Brooks Shera channels can make excellent and productive use of Other Institutions higher duty factors whereas none of the experiments R. Baowkche, Yale University have any need for higher peak machine currents. The Carolus Boekema, Texas Tech University performance of some of the experiments, for example the Gary E. Hogan, Temple University Crystal Box experiment, improves as much as the cube James J. Reidy, University of Mississippi of the duty factor, but improves little, if at all, with higher John Zumbro, Princeton University peak currents. Users therefore request that future im-

November 1983 LAMPF USERS GROUP PROCEEDINGS 115 Los Alamos National Laboratory COMPUTER FACILITIES WORKING GROUP sentiment was expressed for the need to maintain at least the present level of consulting support for both data- James F. Amann, Chairman-Elect acquisition and analysis facilities. A proposal to phase out the Tektronix 4010 terminals in favor of some The first order of business was selecting potential compatible raster-scan terminal such as the Retro- nominees to the Technical Advisory Panel, and M. Graphics VT-640 was not opposed as long as some Oothoudt was nominated and approved unanimously. ability to make a hardcopy of the screen is maintained. Next, nominations for working group chairman were held and J. Amann was nominated and approved ATTENDEES unanimously. Then followed a discussion of the ten- tative recommendations of the computer facilities long- Los Alamos National Laboratory range planning committee as summarized by M. James F. Amann McNaughton. Gail Anderson The proposal to network the data-acquisition com- Peter Berardo puters to the Data-Analysis Center (DAC) was not Richard D. Bolton Harold S. Butler opposed, although there was some comment about how Dan Fitzgerald useful such a facility would be on older (18-bit) PDP-1 Is James F. Harrison with limited physical memory. It was suggested that Martha Hoehn terminal lines from the DAC into the counting houses Earl Hoffman would still serve a useful function. Mark O. Kaletka The proposal to develop a multiprocessor computing Thomas Kozlowski engine based on new Digital Equipment Corporation Michael J. Leitch (DEC) microprocessors, to speed up data processing, Robert J. Macek met with substantial confusion. Some questioned why Dean McMillan Frank Naivar such a device would be/needed and whether or not it Michael Oothoudt would be a good idea to use it in data acquisition. After it Eli Piasetzsky was explained that this would not be a required enhance- Ray Poore ment to the standard systems but rather is intended to Urs Sennhauser speed up analysis for those experiments that need it, E. Brooks Shera most concerns were eliminated. Steve Wilson The proposal to sfowly move toward VAXes for data- acquisition computers and to 1600/6250-bpi tape drives Other Institutions met with reasonable approval. No one objected to Carolus Boekema, Texas Tech University eliminating the ability to write 800-bpi tapes as long as George R. Burleson, New Mexico State University some capability for reading them is maintained on site. Kazuo Gotow, Virginia Polytechnic Institute and State University After some elaboration, the committee's recommenda- John C. Hiebert, Texas A&M University tions on front-end processing, (1) not to pursue the Harold E. Jackson. Jr., Argonne National Laboratory development of a second-generation microprogrammable George J. Kim, University of California branch driver (MBD), and (2) to gain experience with Don Machen, Scientific Systems International FASTBUS by collaboration with other Laboratory Kok-Heong McNaughton, University of Texas groups, were generally approved. Alireza Mokhtari, University of California, Los Angeles The recommendation to tailor the VAXes at the DAC Barry M. Preedom. University of South Carolina to optimize interactive response was approved in prin- Robert P. Redwine, Massachusetts Institute of Technology ciple. Some concern was expressed over exactly how this James J. Reidy, University of Mississippi goal would be implemented. In particular, there was John Ullmann, University of Colorado worry over long jobs being allowed to run interactively, Shen-Wu Xu, University of Texas thereby locking out batch processing. Benjamin Zeidman, Argonne National Laboratory John Zumbro, Princeton University The recommendation not to provide any major enhancements to Q past its extension to support data acquisition on the VAXes concerned some. Substantial

116 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory NEUTRINO FACILITIES WORKING GROUP been accomplished, and the rest should be completed in the next several months. The planned capability of Herbert H. Chen, Chairman LineE is for 20 uA operation, with the potential for upgrade to 200-uA operation. The Exp. 764 detector is T. Romanowski was elected working group chainnan the Exp. 609 detector with some improvements; it is for 1984. No nominations were made for the Technical located now in the assembly building and will be moved Advisory Panel because the neutrino working group has to Line E in the next month or so. Present plans are to two continuing representatives on the panel. run Exp. 764 with beam next year.

Status of Experiments Future Neutrino Beams at LAMPF

Results from preliminary analysis of data taken during The possibility of a neutrino beam from n decay in LAMPF cycle 38 (September 1 -October 17, 1983) for flight in Line A was indicated by R. Carlini. The produc- Exp. 225 were given earlier in the day by H. H. Chen; tion target would be at A-5, with the decay volume Exp. 225 is continuing to take data and likely "nil between A-5 and A-6. Such a facility would have high continue to do so for the next couple of years. intensity and could be relatively inexpensive, but it would Plans for implementing Exp. 645 (Ohio/Argonne/- preempt biomed and isotope production capabilities in Caltech/Louisiana State) were presented by T. Roman- their present locations. However, such a facility may owski. Detailed designs of the three major components couple naturally to stage 1 of LAMFFII. (tunnel, shield, and detector) are complete, and construc- G. Stephenson, Jr., stressed that the upgrade of Line E tion plans are being implemented. It is estimated that to higher intensity and coupling to the Proton Storage tunnel construction will begin during March 1984. Ring (PSR) also has many advantages to recommend it. Associated with this tunnel will be a 12.19- by 12.19-m Some problems are common to both Line E and Line A building for detector assembly and service, and a con- (for example, high-intensity, long di y-factor operation crete pad for shield assembly. The cosmic-ray shield requires an appropriate pion-focusing device). Investigat- design is now settled. It is a 4n shield that has an active ing these possibilities definitely should be pursued. component of liquid scintillator (15.24 cm thick) and a The following list of items (raised by T. Romanowski) passive component of lead and iron (12.7 and 5.1 cm appears appropriate and should be addressed by tl-3 thick, respectively). Bids are being sought for the con- neutrino working group within the next year. struction of this structure, which includes a cart and 1. Develop a coherent plan for neutrino physics at detector support. Production of the detector components LAMPF. ' -•'-"•: will begin shortly. Initial mounting of the detector system 2. Review possible options for neutrino beams with will occur in the assembly building. Test beam studies and without the PSR. with electrons, muons, and protons are intended in the 3. Investigate the following: next few months using prototype components, and a. maximum proton current in target areas, detector assembly should begin by April of next year. b. interference between neutrino and other There is a possibility that some data can be taken with LAMPF programs, beam bofore the scheduled shutdown in October 1984. c. the possibility of combining ;-. beam-dump neu- Over the past year, progress for Exp. 764 (Los trino facility with a pion decay-in-flight neutrino Alamos/New Mexico/Temple/Riverside/Valparaiso/ facility, UCLA) has been very rapid. T. Dombeck reported on d. cost studies for possible neutrino beams, and the status of this project. Implementation of Exp. 764 e. a time schedule for construction of possible requires the construction of Line E in order to produce neutrino beams. v's from (bare target) n decay in flight. Much of this has

November 1983 LAMPF USERS GROUP PROCEEDINGS 117 Los Alamos National Laboratory ATTENDEES Other Institutions Los Alamos National Laboratory Leonard B. Auerbach, Temple University Lewis E. Agnew Herbert H. Chen, University of California, Irvine Charles D. Bowman Hall Crannell, National Science Foundation Roger Carlini Gerald T. Garvey, Argonne National Laboratory Donald R. F. Cochran David Huang, Temple University Joey B. Donahue Gerald C. Phillips, Rice University David M. Lee Thomas A. Romanowski, Ohio State University S. Peter Rosen Elton Smith, Ohio State University Gerard J. Stephenson, Jr.

118 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Gordon S. Mutchler, Tarlochan S. Bhatia, and George Glass

November 1983 LAMPF USERS GROUP PROCEEDINGS 119 Los Alamos National Laboratory I

Clarence R. Richardson, Bob Hardekopf, and P. W. Keaton

Lee C. Teng, Pete Miller, Henry A. Thiessen, and Erich Vogt

120 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Steven Wallace and Kevin W. Jones

Robert Eisenstein

November 1983 LAMPF USERS GROUP PROCEEDINGS 121 LOS Alamos National Laboratory Louis Rosen and George Igo

Clarence Richardson

Ben Nejkens and Yugi Ohashi

November 1983 122 LAMPF USERS GROUP PROCEEDINGS Los Alamos National Laboratory Pete Miller

James J. Reidy, Barry M. Preedom, Peter Riley, Michael McNaughton, Charles L. Hollas, and Stanley A. Dodds

November 1983 LAMPF USERS GROUP PROCEEDINGS 123 Los Alamos National Laboratory Herbert Chen, James S. Frank, and Urs Sennhauser

William R. fVharton and Joe Comfort

Kenneth Crowe and Robert Sherman

124 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Joey B. Donahue, Dan Fitzgerald, and Richard D. Werbeck Charles Glashausser Chairman of the Board January 1984

John McGill and Norton Hintz

November 1983 LAMPF USERS GROUP PROCEEDINGS 125 Los Alamos National Laboratory PARTICIPANTS OF THE SEVENTEENTH LAMPF USERS GROUP MEETING

Bjarne Aas Andrew Bacher Richard D. Bolton UCLA/Los Alamos National Cyclotron Facility Los Alamos National Laboratory Laboratory Indiana University MP-4, MS H846 MS-H731 Bloomington, IN 47401 Richard L. Boudrie Lewis E. Agnew R. Baowkche Los Alamos National Laboratory Los Alamos National Laboratory Department of Physics MP-10, MS H841 MP-7, MS H840 Yale University New Haven, CT 06520 Charles Bowman John C. AUred Los Alamos National Laboratory Los Alamos National Laboratory Benjamin E. Bayman P-DO, MS D443 MP-DO, MS H850 Physics Department University of Minnesota James Bradbury Peter W. F. Alons Minneapolis, MN 55455 Los Alamos National Laboratory Fnysics Department MP-3, MS H844 University of Colorado Peter D. Barnes Boulder, CO 80309 Physics Department Daeg S. Brenner Carnegie-Mellon University Chemistry Department Jonas Alster Pittsburgh, PA 15213 Clark University Physics Department Worcester, MA 01610 Tel Aviv University Peter Berardo Tel Aviv, Israel Los Alamos National Laboratory Andrew Browman MP-3, MS H809 Los Alamos National Laboratory James F. Amann MP-DO, MS H832 Los Alamos National Laboratory R. S. Bhalerao MP-10, MS H841 Los Alamos National Laboratory Robert D. Brown INC-11, MSH824 Los Alamos National Laboratory Alan N. Anderson MP-7, MS H840 EG&G. Idaho Tarlochan S. Bhatia Idaho Falls, ID 8'

126 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Robert Burman Donald R. F. Cochran Kalvir Dhuga Los Alamos National Laboratory Los Alamos National Laboratory Physics Department MP-4, MS H846 MP-DO, MS H830 University of Pennsylvania Philadelphia, PA 19104 Gilbert Butler Eugene Colton Los Alamos National Laboratory Los Alamos National Laboidtory Stanley A. Dodds INC-11,MSJ514 MP-14, MS H847 Rice University Physics Department Harold S. Butler Joe Comfort Houston, TX 77251 Los Alamos National Laboratory Physics Department MP-DO, MS H832 Arizona State University Joey B. Donahue Tempe, A7 85381 Los Alamos National Laboratory Tom Carey MP-7, MS H831 Los Alamos National Laboratory Jay H. Cook P-3, MS D456 Los Alamos National Laboratory Bruce J. Dropesky MST-14, MS G 742 Los Alamos National Laboratory R.oger Carlini INC-11, MS H8?.4 Los Alamos National Laboratory D. Wayne Cooke MP-14, MS H847 Los Alamos National Laboratory Gerald Dugan MP-3, MS H844 Fermilab Edwin P. Chamberlin P. O. Box 500 Los Alamos National Laboratory James R. Cost Batavia, IL 60510 MP-11,MS H823 Los Alamos National Laboratory MST-5, MS G734 Peggy Dyer Herbert Chen Los Alamos National Laboratory Physics Department William Cottingame P-3, MS D456 University of California, Irvine New Mexico State University/ Irvine, CA 92717 Los Alamos National Laboratory Robert Eisen stein MP-10, MSH841 Physics Department K. W. Chen Carnegie-Mellon University Physics Department Hall Crannell Pittsburgh, PA 15213 University of Texas, Arlington National Science Foundation Arlington, TX 76019 1800 G Street N.W. Jon En gel age Washington, DC 20550 UCLA/Los Alamos National Huan-Ching Chiang Laboratory Los Alamos National Laboratory Kenneth Crowe MS H831 MP-4. MS H846 Lab. Bldg. 50, Rm. 205 Lawrence Berkeley Laboratory David J. Farnum Robert Chrien Berkeley, CA 94720 Los Alamos National Laboratory Physics Department MP-13, MS H838 Brookhaven National Laboratory Frank Cverna Upton. NY 11973 Los Alamos National Laboratory Dan Fitzgerald P-15, MS D406 Los Alamos National Laboratory David A. Clark 1V.P-13. MS H838 Los Alamos National Laboratory Robert P. Damjanovich P-9, MS H8O5 Los Alamos National Laboratory Gottfried Flik MP-8, MS H826 Max Planck Institute Frank W. Clinard Stuttgart, Germany Los Alamos National Laboratory Dorothy D. Davidson MST-5, MS E546 Los Alamos National Laboratory MP-3, MS H809

November 1983 LAMPF USERS GROUP PROCEEDINGS 127 Los Alamos National Laboratory Terry Fortune Charles Glashausser Carol Harvey Physics Department Physics Department University of New Mexico/ University of Pennsylvania Rutgers University Los Alamos National Laboratory Philadelphia, PA 19104 Piscataway, NJ 00854 MS H841

James S. Frank George Glass Rene Hausammann Los Alamos National Laboratory Texas A&M University/ University of California, Irvine/ MP-4, MS H846 Los Alamos National Laboratory Los Alamos National Laboratory MS H831 MS H831 Dan Fraser Los Alamos National Laboratory Terry Goldman Robert H. HefFner T-5, MS B283 Los Alamos National Laboratory Los Alamos National Laboratory T-5, MS B283 MP-3, MS H844 Gerald T. Garvey Physics Division, 203, F-139 Kazuo Gotow Leon Heller Argonne National Laboratory Physics Department Los Alamos National Laboratory Argonne, IL 60439 Virginia Polytechnic Institute and T-5, MS B283 State University Mohamed Magdy Gazzaly Blacksburg, VA 24061 John C. Hiebert Physics Department Cyclotron Institute University of California, Steven J. Greene Texas A&M University Los Angeies Los Alamos National Laboratory College Station, TX 77843 Los Angeles, CA 90024 MP-10, MS H841 Norton Hintz Donald F. Geesaman David Grosnick Physics Department Argonne National Laboratory University of Chicago/ University of Minnesota Argonne, IL 60439 Los Alamos National Laboratory Minneapolis, MN 55455 MS H831 Benjamin F. Gibson Martha Hoehn Los Alamos National Laboratory Wifli Gruebler Los Alamos National Laboratory T-5, MS B283 ETH MP-I, MS H810 CH-8093 Zurich Edward F. Gibson Switzerland Gary E. Hog an California State University Temple University/ Physics Department Calvin F. Hansen Los Alamos National Laboratory Sacramento, CA 95819 Los Alamos National Laboratory MS H838 MP-13, MS H838 Gregg Giesler Cyrus M. Hoffman Los Alamos National Laboratory Ron Harper Los Alamos National Laboratory INC-II, MS H824 Los Alamos National Laboratory MP-4, MS H846 MP-4, MS H846 Ronald Gilman Darieane C. Hoffman University of Pennsylvania/ James F. Harrison Los Alamos National Laboratory Los Alamos National Laboratory Los Alamos National Laboratory INC-DO, MSJ5I5 MP-10, MS H831 MP-1, MS H810 Earl Hoffman J. Ginocchio Alexander Harvey Los Alamos National Laboratory Los Alamos National Laboratory Los Alamos National Laboratory MP-1, MS H828 T-5, MS B283 AT-3, MS H8O8

128 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Charles L. Hollas M. William Johnson Alan Krisch University of Texas/ Los Alamos National Laboratory Physics Department Los Alamos National Laboratory Q-2, MS J562 University of Michigan MSH831 Ann Arbor, MI 48109 Kevin W. Jones Roy J. Holt Los Alamos National Laboratory Robert H. Kraus, Jr. Physics Division MP-DO, MS H841 Oregon State University Argonne National Laboratory Radiation Center Argonne, IL 60439 Steven E. Jones Corvallis, OR 97331 EG&G, Idaho David Huang P.O.Box 1625 Jutta Kunz Department of Physics Idaho Falls, ID 83415 Los Alamos National Laboratory Temple University T-9, MS B279 Philadelphia, PA 19122 James Kelly Los Alamos National Laboratory George P. Lawrence Ed Hungerford MP-4, MS H846 Los Alamos National Laboratory Physics Department AT-3, MS H808 University of Houston George Kim Houston, TX 77004 Physics Department Michael E. Lazarus University of California, Los Angeles Los Alamos National Laboratory Richard L. Hutson Los Angeles, CA 90024 MST-14, MS G742 Los Alamos National Laboratory MP-3, MS H844 Tom King Catherine Lechanoine-Leluc Los Alamos National Laboratory University of Geneva George Igo WX-11, MSC948 Geneva, Switzerland Physics Department University of California, Los Angeles W. Wayne Kinnison David M. Lee Los Angeles, CA 90024 Los Alamos National Laboratory Los Alamos National Laboratory P-DO, MS O443 MP-13, MSH838 Farokh Irom Los Alamos National Laboratory Leonard Kisslinger Michael J. Leitch MP-4, MS H846 Physics Department Los Alamos National Laboratory Carnegie-Mellon University INCH, MSH824 Harold E. Jackson, Jr. Pittsburgh, PA 15213 Argonne National Laboratory Melvin Leon Argonne, IL 60439 Harold B. Knowles Los Alamos National Laboratory University of New Mexico MP-3, MS H844 John J. Jarmer 11113 Brentwood Hills Blvd., N.E. Los Alamos National Laboratory Albuquerque, NM 87112 T. K. Li MP-7, MS H840 Los Alamos National Laboratory Ralph Korteling Q-l, MSE540 Nelson Jarmie Department of Chemistry Los Alamos National Laboratory Simon Fraser University Roger Lichti P-3, MS D456 Burnaby, British Columbia Texas Tech University Canada V5A IS6 Lubbock, TX 79409 Mikkel Johnson Los Alamos National Laboratory Thomas Kozlowski Raimond Liepins MP-DO, MS H85O Los Alamos National Laboratory Los Alamos National Laboratory MP-1, MS H828 MST-6, MS E528

November 1983 LAMPF USERS GROUP PROCEEDINGS 129 Los Alamos National Laboratory David Lind Bill W. Mayes, II Murray Moinester Physics Department Physics Department Physics Department University of Colorado University of Houston Tel Aviv University Boulder, CO 80309 Houston, TX 77004 Tel Aviv, Israel

Lon-Chang Liu Robert McAdams Alireza Mokhtari Los Alamos National Laboratory Physics Department Physics Department INC-11,MSH824 Utah State University University of California, Los Angeles Logan, UT 84322 Los Angeles, CA 90024 D. Lopiano Physics Department J. B. McClelland C. Fred Moore University of California, Los Angeles Los Alamos National Laboratory Physics Department Los Angeles, CA 90024 MP-10, MS H841 University of Texas Austin, TX 78712 Lynn B. Lundberg Robert J. McKee Los Alamos National Laboratory Los Alamos National Laboratory Christopher L. Morris Q-13, MSG576 P-DO, MS D443 Los Alamos National Laboratory MP-10, MS H841 Duncan MacArthur John A. McGill Los Alamos National Laboratory Rutgers University/ Joel M. Moss MP-4, MS H846 Los Alamos National Laboratory Los Alamos National Laboratory MS H841 P-3, MS D-'rS Robert J. Macek Los Alamos National Laboratory Joseph L. McKibben Gordon S. Mutchler MP-I3, MSH838 Los Alamos National Laboratory Physics Department P-9, MS K480 Rice University Malcolm MacFarlane Houston, TX 77251 Physics Department Dean McMillan Indiana University Los Alamos National Laboratory D. E. Nagle Bloomington, IN 47405 P-9, MS K480 Los Alamos National Laboratory MP-DO, MS H846 Donald R. Machen Kok-Heong McNaughton Scientific Systems International Physics Department Franklin J. Naivar 3491 B Trinity Dr. University of Texas, Austin Los Alamos National Laboratory Los Alamos, NM 87544 Austin, TX 78712 C 5, MS B255

Kazushige Maeda Michael McNaughton Ben Nefkens Tohoku University/ Los Alamos National Laboratory Physics Department Los Alamos National Laboratory MP-13, MS H838 University of California, Los Angeles MS H831 Los Angeles, CA 90024 Sydney Meshkov Fesseha G. Mariam National Bureau of Standards Charles R. Newsom Los Alamos National Laboratory Washington, DC 20234 Physics Department MP-13, MSH838 University of California, Los Angeles R. E. Mischke Los Angeles, CA 90024 Jill Marshall Los Alamos National Laboratory University of Texas, Austin/ MP4, MS H846 Michael M. Nieto Los Alamos National Laboratory Los Alamos National Laboratory MS H831 T-8, MS B285

130 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory L. C. Northcliffe Charles F. Perdrisat Glen A. Rebka, Jr. Cyclotron Institute Physios Department Department of Physics Texas A&M University College of William and Mary University of Wyoming College Station, TX 77843 Williamsburg, VA 23185 Laramie, WY 82071

Jan K. Novak R. J. Peterson Robert P. Redwine Los Alamos National Laboratory Nuclear Physics Laboratory Physics Department, 26-447 MP-7, MS H840 Campux Box 446 Massachusetts Institute of Technology University of Colorado Cambridge, MA 02139 Hal O'Brien Boulder, CO 80309 Los Alamos National Laboratory Robert C. Reedy INC-3, MSJ514 Gerald C. Phillips Los Alamos National Laboratory Bonner Nuclear Laboratories INC-11, MS J514 Yuji Ohashi Rice University University of California, Los Angeles/ P. O. Box 1892 Lawrence B. Rees Los Alamos National Laboratory Houston, TX 77251 Los Alamos National Laboratory MS H831 P-3, MS D456 Eli Piasetzky Yoshitaka Ohkubo Los Alamos National Laboratory James J. Reidy Los Alamos National Laboratory MP-4, MS H846 Department of Physics INC-11. MSH824 University of Mississippi Chandra Pillai University, MS 38677 Michael Oothoudt Oregon State University/ Los Alamos National Laboratory Los Alamos National Laboratory Clarence R. Richardson MP-1, MSH828 INC-11, MSH824 Department of Energy Nuclear Physics Division, ER-23 Charles Orth Lawrence Pinsky Washington, DC 20545 Los Alamos National Laboratory Physics Department INCH, MSJ514 University of Houston Peter Riley Houston, TX 77004 Physics Department Zack Os borne University of Texas Los Alamos National Laboratory Ray Poore Austin, TX 78712 WX-11. MS C948 Los Alamos National Laboratory P-9, MS K480 Barry G. Ritchie Takaharu Otsuka Physics Department Los Alamos National Laboratory R. C. Potter University of Maryland T-5. MS B283 Los Alamos National Laboratory College Park. MD 20742 MP-13, MS H838 Don M. Parkin R. G. Hamish Robertson Los Alamos National Laboratory Barry M. Preedom Los Alamos National Laboratory MST-5, MS G73O Physics Department P-3, MS D456 University of South Carolina Gianni Pauletta Columbia, SC 29208 Sayed H. Rokni University of California, Los Angeles/ Utah State University/ Los Alamos National Laboratory Thomas M. Putnam Los Alamos National Laboratory MS H831 Los Alamos National Laboratory INC-11, MS H824 MP-DO, MS H83O

November 1983 LAMPF USERS GROUP PROCEEDINGS 13 1 Los Alamos National Laboratory Thomas A. Romanowski Richard R. Silbar Willard L. Talbert Physics Department Los Alamos National Laboratory Los Alamos National Laboratory Ohio State University T-5, MS B283 INC-11, MS J514 Columbus, OH 43210 James E. Simmons Nobuyuki Tanaka Louis Rosen Los Alamos National Labora Los Alamos National Laboratory Los Alamos National Laboratory P-3, MS D456 MP-10, MS H841 MP-DO, MS H850 Elton Smith Lee C. Teng S. Peter Rosen Smith Lab. Fermilab Los Alamos National Laboratory Ohio State University P. O. Box 500 P-DO, MS D434 Columbus, OH 43202 Batavia, IL 60510

Richard D. Ryder W. F. Sommer Henry A. Thiessen Los Alamos National Laboratory Los Alamos National Laboratory Los Alamos National Laboratory P-9, MS H8O5 MP-13, MS H838 MP-14, MS H847

Vern Sandberg Gerard J. Stephenson, Jr. Alvin Trivelpiece Los Alamos National Laboratory Los Alamos National Laboratory Department of Energy MP-4, MS H846 P-DO, MS D443 Washington, DC 20545

Gary H. Sanders Ralph R. Stevens, Jr. Sun Tsu-Hsun Los Alamos National Laboratory Los Alamos National Laboratory Los Alamos National Laboratory MP-13, MSH838 MP-DO, MS H823 MP-10, MS H841

James E. Sattizahn Dan Strottman John Ullmann Los Alamos National Laboratory Los Alamos National Laboratory Physics Department INC-11, MS J514 T-9, MS B279 University of Colorado Boulder, CO 80309 Susan Seestrorn-Morris Harold Spinka University of Minnesota/ Bldg. 362 Olin B. van Dyck Los Alamos National Laboratory Argonne National Laboratory Los Alamos National Laboratory MP-10, MS H841 Argonne, IL 60439 MP-DO, MS H832

Peter Seidl J. Stanley W. J. van Dyke University of Texas/ Los Alamos National Laboratory Los Alamos National Laboratory Los Alamos National Laboratory MST-5, MS G734 MP-8, MS H826 MS H841 Nelson Stein Kamran Vaziri Urs Sennhauser Los Alamos National Laboratory Utah State University/ Los Alamos National Laboratory P-3, MS D456 Los Alamos National Laboratory MP-4, MS H846 INC-11, MS H824 Richard Talaga E. Brooks Shera Physics Department David J. Vieira Los Alamos National Laboratory University of Maryland Los Alamos National Laboratory P-3, MS D456 College Park, MD 20742 INCH, MS H824

132 LAMPF USERS GROUP PROCEEDINGS November 19.83 Los Alamos National Laboratory Steven Vigdor Monroe S. Wechsler Shen-Wu Xu Cyclotron Facility Los Alamos National Laboratory Physics Department Indiana University MP-3, MS H8O9 University of Texas, Austin Bloomington, IN 47405 Austin, TX 78712 Richard D. Werbeck Erich Vogt Los Alamos National Laboratory Peter Yamin University of British Columbia MP-7, MS H840 Brookhaven National Laboratory Vancouver, British Columbia Upton, NY 11973 Canada V6T 2A3 Gary Weston University of California, Los Angeles/ Shu-Heng Yan J. Dirk Walecka Los Alamos National Laboratory Los Alamos National Laboratory Physics Department MS H831 INC-11, MS J514 Stanford University Stanford, CA 94305 William R. Wharton Akihiko Yokosawa Physics Department Physics Department Donald I. Walker Carnegie-Mellon University Argonne National Laboratory Associated Western Universities, Inc. Pittsburgh, PA 15213 Argonne, IL 60439 142 East 200 South, No. 200 Salt Lake City, UT Robert A. Williams Vincent Yuan Los Alamos National Laboratory University of Illinois/ Steven Wallace MP-4, MS H846 Los Alamos National Laboratory Department of Physics MP-4, MS H846 University of Maryland John F. Wilkerson College Park, MD 20742 Los Alamos National Laboratory Benjamin Zeidman P-3, MS D456 Argonne National Laboratory John Walter Argonne, IL 60439 EG&G, Idaho Steve Wilson Idaho Falls, ID 84315 Stanford University/ Hans-Joachim Ziock Los Alamos National Laboratory University of California, Los Angeles/ Angel Wang MS H846 Los Alamos National Laboratory University of California, Los Angeles/ MS H831 Los Alamos National Laboratory Richard Woods MS H831 Los Alamos National Laboratory Klaus Ziock P-9, MS K840 Physics Department Robert F. Warner University of Virginia Los.Alamos National Laboratory Jan M. Wouters Charlottesville, VA 22901 MP-DO, MS H842 Los Alamos National Laboratory INC-11, MSH824 John D. Zumbro Princeton University/ Los Alamos National Laboratory MS H831

November 1983 LAMPF USERS GROUP PROCEEDINGS 133 Los Alamos National Laboratory LAMPF USERS GROUP NEWS

1984 BOARD OF DIRECTORS OF THE LAMPF USERS GROUP, INC.

The Board of Directors consists of a Secretary/Treasurer and seven members elected by the LAMPF Users Group, Inc., whose interests they represent and promote. They concern themselves with LAMPF programs, policies, future plans, and especially with how Users are treated at LAMPF. Users should address problems and suggestions to individual Board members. The Board also nominates new members to the Program Advisory Committee (PAC). The 1983 membership and term expiration dates are listed below.

1985 Charles Glashausser (Chairman) 1984 Andrew D. Bacher Rutgers University Indiana University 1986 Robert Redwine (Chairman-Elect) 1985 Peter D. Barnes Massachusetts Institute of Technology Carnegie-Mellon University 1984 George Igo (Past-Chairman) 1985 Barry Preedom University of California, Los Angeles University of South Carolina James Bradbury (Secretary/Treasurer) 1985 John D. Walecka Los Alamos National Laboratory Stanford University

1984 WORKING GROUP CHAIRMEN High-Resolution Spectrometer (HRS) Energetic Pion Channel and Computer Facilities M. Gazzaly Spectrometer (EPICS) James F. Amann University of Minnesota William Cottingame Los Alamos National Laboratory New Mexico State University/ Neutrino Facilities Los Alamos National Laboratory Solid-State Physics and Thomas A. Romanowski Materials Science Ohio State University High-Energy Pion (P3) Channel Walter F. Sommer Jon Engelage Los Alamos National Laboratory Stopped-Muon Channel (SMC) University of California, Fesseha Mariam Los Angeles Muon-Spin Rotation (uSR) Los Alamos National Laboratory Art Denison Nucleon Physics Laboratory (NPL)/ University of Wyoming Nuclear Chemistry Polarized Facilities Yoshitaki Ohkubo Tarlochan Bhatia Low-Energy Pion (LEP) Channel Los Alamos National Laboratory Texas A&M University/ Michael J. Leitch Los Alamos National Laboratory Los Alamos National Laboratory

134 LAMPF USERS GROUP PHOCEEDINGS November 1983 Los Alamos National Laboratory NOTICE The Eighteenth Annual Meeting of the LAMPF Users Group, Inc., will be held in Los Alamos on October 29 and 30, 1984.

LAMPF PROGRAM ADVISORY COMMITTEE (PAC)

The PAC consists of about 25 members appointed for staggered 3-year terms. Members advise the Director of LAMPF on the priorities they deem appropriate for the commitment of beam time and the allocation of resources for the development of experimental facilities. The PAC meets twice each year for 1 week during which time all new proposals that have been submitted at least 2 months before the meeting date are considered. Old proposals, and the priorities accorded to them, may also be reviewed.

Terms Expiring 1983

Richard Arndt Robert Redwine S. Peter Rosen Virginia Polytechnic Institute Massachusetts Institute of Technology Los Alamos National Laboratory and State University Louis Remsberg Stephen J. Wallace Dieter Kurath Brookhaven National Laboratory University of Maryland Argonne National Laboratory

Terms Expiring 1984

Franz L. Gross Leonard S. Kisslinger Darragh Nagle College of William & Mary Carnegie-Mellon University Los Alamos National Laboratory

Barry Holstein June L. Matthews Bruce VerWest University of Massachusetts Massachusetts Institute of Technology Arco Oil and Gas Company

Sheldon B. Kaufman Daniel W. Miller Robert Lee Walker Argonne National Laboratory Indiana University Tesuque, New Mexico

Terms Expiring 1985

David Axen Frieder Lenz Victor E. Viola, Jr. TRIUMF SIN Indiana University

Barry Barish Harold M. Spinka, Jr. Larry Zamick California Institute of Technology Argonne National Laboratory Rutgers University

Dietrich Dehnhard University of Minnesota

November 1983 LAMPF USERS GROUP PROCEEDINGS 135 Los Alamos National Laboratory 1984 TECHNICAL ADVISORY PANEL (TAP) OF THE LAMPF USERS GROUP, INC.

The TAP provides technica! recommendations to the Board of Directors and LAMPF management about the development of experimental facilities and experiment support activities. The TAP has 12 members, appointed by the Board of Directors, serving 3-year staggered terms. The Chairman of the Board of Directors serves as TAP chairman. The TAP membership and term expiration dates are listed below.

1984 Billy E. Bonner 1985 Christopher L. Morris Los Alamos National Laboratory Los Alamos National Laboratory

1984 Thomas J. Bowles 1986 Michael A. Oothoudt Los Alamos National Laboratory Los Alamos National Laboratory

1986 George R. Burleson 1984 Barry Preedom New Mexico State University University of South Carolina

1984 Gerald Dugan 1985 Thomas A. Romanowski Fermi National Accelerator Laboratory Ohio State University

1985 Donald Geesaman 1986 Gary Sanders Argonne National Laboratory Los Alamos National Laboratory

1985 KazuoGotow 1986 Charles A. Whitten Virginia Polytechnic Institute and State University of California, University Los Angeles

SCIENCE POLICY ADVISORY COMMITTEE (SPAC)

A Science Policy Advisory Committee was formed during 1983 to advise the Board of Directors on the long-term development of research and facilities at LAMPF. The first charge to the SPAC was the examination of the LAMPF II concept and justification in the context of nuclear and particle physics needs of the 1990s.

Barry C. Barish Frederick Reines California Institute of Technology University of California, Irvine

Leonard S. Kisslinger S. Peter Rosen Carnegie-Mellon University Los Alamos National Laboratory

Alan D. Krisch Lee C. Teng University of Michigan Fermi National Accelerator Laboratory

Malcolm MacFarlane Akihiko Yokosawa Indiana University Argonne National Laboratory

Sydney Meshkov John D. Walecka National Bureau of Standards Stanford University

136 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory LAMPF USERS GROUP, INC., (LUGI), MINUTES

BOARD OF DIRECTORS

The LAMPF Users Group Board of Directors (BOD) The criteria for thesis evaluation were discussed. In met on March 6-7, July 20-21, and November 8, 1983. addition to intellectual content, quality of presentation, All meetings were chaired by George Igo; selected topics and significance of results, the level of the contributions of discussion are provided below. to the work by the student is obviously important. The 1983 Annual Users Meeting was very successful. Contributions to the experiment design, data analysis, There were 222 registrants, of whom 119 were from and data interpretation are to be assessed by requiring outside the Laboratory. The panel discussion about explanatory letters from both student and advisor. LAMPF II, involving the BOD, the Science Policy Ad- The BOD selected Stephen A. Wood as the recipient of visory Committee (SPAC), and the attending Users, the Louis Rosen Prize for 1983. The title of the thesis is received favorable comments for being stimulating and "An Experimental Study of Inclusive Pion Double- informative. A summary of the discussion is provided in Charge-Exchange Reactions in the Delta Resonance these proceedings. Region." Sixty-one new proposals were received for review by MP Division has purchased a 10- by 55-ft trailer to be the Program Advisory Committee (PAC) at the January equipped as a Users lounge. The trailer will be located 1984 meeting. The breakdown by channel follows: to the east of the Data-Acquisition Center and will arrive EPICS - 15, HRS - 10, NPL - 7, LEP - 12, P3 - 11, about December-1, 1983. The lounge will contain space SMC-3, Neutrino-1, Radiation Effects-1, and Nu- for a library, kitchen, and computer terminal as well as a clear Chemistry- 1. Because of the proposal load, the large open area; some landscaping in the vicinity is Low-Energy Pion channel (LEP) and the High-Energy planned. Users representatives will be asked to consider 3 Pion channel (P ) PAC subcommittees will have one furnishings for the lounge and arrange for their purchase more member (either from the Laboratory or from with Users funds available for this purpose. another subcommittee) for the January meeting. George Igo announced the formation of a Science Those PAC members whose terms nominally expire in Policy Advisory Committee (SPAC) whose role is to 1983 have been asked, as usual, to serve in January and advise on the long-term development of research and also to serve at the summer meeting in 1984, as there was facilities at LAMPF. The following persons participated no meeting in the summer of 1983. The summer 1984 in an organizational meeting on July 26, 1983. meeting will thus be the "overlap" meeting. New PAC Barry Barish Caltech members will be recommended by the BOD at their next Leonard Kisslinger Carnegie-Mellon University meeting. Alan Krisch University of Michigan Four new members were appointed to the Technical Sydney Meshkov National Bureau of Standards Advisory Panel from the lists provided by the LUGI Fredrick Reines University of California/Irvine working groups. The appointees are Michael Oothoudt, Peter Rosen Los Alamos National Laboratory Computer Facilities; Gary Sanders, Stopped-Muon Dirk Walecka Stanford University Channel (SMC); George Burleson, Energetic Pion Chan- Akihiko Yokosawa Argonne National Laboratory nel and Spectrometer (EPICS); and Charles Whitten, High-Resolution Spectrometer (HRS). The first charge to the SPAC is to examine the present The Board agreed to employ Users Group funds to LAMPF II concept and physics justification in the establish and support a new award, the Louis Rosen context of nuclear and particle physics needs of the Prize. This prize, consisting of $1000 and a certificate, is 1990s. The committee is to advise the LUGI-BOD on to be awarded annually for the outstanding Ph.D. thesis • specific strengths and weaknesses in the LAMPF II based on LAMPF research. The judging is to be done by concept and justification, the Board of Directors. For consideration, theses should • the highest priority experimental programs and be submitted to the Users Group Office at LAMPF by facilities to be developed at LAMPF II, and August 31; announcement of the winner will be made at • the best strategies for advancing the case and the Users Meeting in November. To be eligible, a thesis developing support for LAMPF II in the nuclear must have been completed since the previous August. and particle physics communities.

November 1983 LAMPF USERS GROUP PROCEEDINGS 137 Los Alamos National Laboratory The SPAC met on October 22, 1983, at UCLA. Following a suggestion by Louis Rosen, plans are Preliminary reports were presented on four topics impor- being m de to hold a comprehensive workshop in May of tant to the LAMPF II concept: accelerator design (Alan 1984 on the interface between particle and nuclear Krisch), experimental facilities (Akihiko Yokosawa), and physics, "i >vo members of the SPAC, Alan Krisch and physics justification and community support (Barry Malcolm MacFarlane, have agreed to head an organizing Barish). George Igo will assemble the written reports and committee for this workshop. A one-half-day session of send them, together with a summary of the panel dis- invited papers on the interface region will be held at the cussion during the Annual Users Meeting, to the Users. spring APS meeting. This is a crucial period for LAMPF II because the To bolster the case for LAMPF II, it is important to concept and justification must become firm very soon in publicize the achievements of existing meson factories order to produce a proposal by the end of 1984. Strong and their impact on the development of nuclear physics. support of physicists in both nuclear and particle physics Members of LUGI are encouraged to give presentations must be garnered and maintained. Consequently the at universities and an article should be prepared for BOD feels that the SPAC should be requested to con- Physics Today. A semitechnical brochure on LAMPF tinue to provide input to the LAMPF II plan. A nuclear accomplishments could also be prepared for widespread physics subcommittee of the SPAC will be organized by distribution. C. Glashausser to define more precisely the potential of The Annual Users Meeting in 1984 will be held on LAMPF II in this area. October 29-30 (November 6 is election day). The next BOD meeting will be on February 17, 1984, at LAMPF.

TECHNICAL ADVISORY PANEL

The Technical Advisory Panel (TAP) met on July 29 Congress aware that they need and will use a LAMPF II. and November 6, 1983. Some excerpts of the minutes are In addition to the in-house work of Los Alamos in terms presented below. After noting that the budgetary position of proposal preparation, there must be a well-established of LAMPF appears reasonable for FY 1984, Louis effort by external users to define and support LAMPF II. Rosen made some general comments about the LAMPF Richard Boudrie reported that the new Low-Energy neutrino program. The proposed neutrino program using Pion Channel (LEP) spectrometer project is proceeding the Proton Storage Ring (PSR) is in abeyance at this time, very well. The spectrometer will be useful for pion primarily because the neutron scattering and defense inelastic scattering in the 20- to 80-MeV range and will programs have first priority on PSR beam and it is not provide <0.1% resolution with large acceptance. The clear that an adequate amount of current will be available pole pieces ?.r.d yoke are presently being machined at a for the neutrino program. However, as neutrino physics is cost much less than anticipated; the vacuum can has been an important component of LAMPF research, experi- cast and vacuum tests will soon be performed. It is ments are being conducted at the beam stop and Line E. expected that the poles, yoke, and vacuum can will be At Line E, neutrino cross sections will be measured using assembled and doweled at the machine-shop facility by a 5-ton liquid scintillator detector (Exp. 764). LAMPF late September. One coil has been fabricated and the will provide up to $200 thousand to prepare Line E, second coil is expected by October. which is expected to be ready to receive beam in January A conceptual design and drawing have been completed 1984. If approved by PAC, a modular detector may be for the scattering chamber and target mechanism. Com- constructed, which might eventually be used at ments are being solicited from potential users and engi- LAMPF II. neers. Studies have been made regarding the relative Louis Rosen commented that for long-term survival, merits of the vertical drift (VDC) and MP-10 drift LAMPF needs a major upgrade. He feels that the chambers for the focai plane. Tests of the MP-10-style Laboratory top management will support such a project, chambers at a 45° angle of incidence for the incoming as it clearly will provide important opportunities for particle will be made at the end of cycle 38 to evaluate performing high-quality research and for extending the their performance. The project is on schedule and within base for education of young scientists. Interested mem- the budget of $350 thousand. A working system ready to bers of the scientific community must make the DOE and accept beam is expected by April 1984.

138 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Helmut Baer reviewed the development history and continuation of this program are being reviewed. Design current performance characteristics of the n° spec- work for the HRS focal-plane shielding is complete, but trometer. Highlights of the reset "h program include the installation in 1984 will be in conflict with the polarized- studies of isobaric analogs to determine the isovector target setup. The shielding will be deferred until 1985 if component of the optical potential, and the studies of the polarized-target program is scheduled for 1984. giant resonances with (n^ir0) reactions. Of particular Planned modifications to the beam-stop area were significance is the presence of the nuclear monopole presented by Walter Sommer. The major design consider- signal. ations and goals are to provide The n° spectrometer is capable of obtaining a resolu- • improved environment for beam-line diagnostics, tion of 2-MeV FWHM, although 4 MeV is more typical. • improved shielding and elimination of cracks to To make a significant improvement in resolution, the y- reduce leakage of activated gas, ray energy resolution must be improved. If the photon • new facility for proton- and neutron-radiation- resolution were 5% FWHM at 100 MeV, the n° energy effects studies that allows multiple bulk samples and resolution could be improved to approximately 0.5 MeV control of irradiation parameters, FWHM. Monte Carlo design studies are being performed • improved facility for high-speed and ultra-high- to determine the advantages of replacing the lead-glass speed isotope transport and identification, photon detectors with either Nal or BGO modular • access for additional experiment initiatives in nu- arrays. Such an improvement might cost about $1 clear and solid-state physics, million. If the modification project is deemed worthwhile, • remote handling and shielded transport of radioac- the group will prepare a detailed proposal for evaluation tive material, and by the TAP. • one-day repair/replacement of components or ex- LAMPF may be able to acquire a new polarized ion perimental hardware. source with I to 2 orders of magnitude higher intensity Design of the new facility is nearing completion and than the present source at a cost of several million dollars accelerator improvement funds are available for the and several man-years of effort. Perhaps Accelerator project. Material procurement and fabrication have been Improvements Project (AIP) funds (estimated to be about initiated, and a schedule calling for completion in the $1 million per year after FY 1984) could be used. It is spring of 1985 has been established. necessary, however, to evaluate the physics justification A status report on the Long-Range Planning Commit- for such a source, and a workshop will be convened for tee for LAMPF Computing Needs was presented by that purpose in November. Martha Hoehn. The committee met for 3 days, October Billy Bonner discussed his investigation of new 24-26, 1983. polarized ion source possibilities for LAMPF. The Na- The committee generally discussed topics in two areas: tional Laboratory for High-Energy Physics in Japan data acquistion and data analysis. A few notable points in (KEK) has developed an optically pumped source with each section were presented to the TAP. demonstrated output of 10-25 uA and an anticipated Five topics were discussed for data acquisition: output of about 60 uA. An atomic beam ion source (1) front-end processing, (2) hardware standards, (3) buf- (Gruebler, SIN) has produced 6 uA with projections fer processors, (4) data acquisition program Q, and (perhaps optimistic) of 100 uA. A 20-uA source would (5) networks in the experimental area. These are briefly provide an increase in intensity by a factor of 50-100 over summarized below. the present LAMPF source. I. Front-end processing. The committee heard a pres- Lewis Agnew reported on experimental-area develop- entation by James Amann summarizing the status ment projects. The A-2 target cell was rebuilt during the of the committee looking into this topic. The micro- 1983 shutdown. Production currents up to 900 ,iA have programmable branch driver (MBD) does not been achieved on Line A. Replacement of the A-l target satisfy all the needs of the users, but there is no cell is phnned for the 1984 spring shutdown. Both the obvious candidate for a replacement. It appears LEP and time-of-flight isochronous (TOFI) spec- that auxiliary crate controllers may solve some trometers are making reasonable progress; first use of the problems for some applications. A new high-speed LEP spectrometer is planned for next summer. The flexible electronics system, FASTBUS, looks like a polarized-target program at the High-Resolution Spec- promising technology to pursue, and the committee trometer (HRS) was successful; plans for the 1984 recommended that Group MP-1 should do that.

November 1983 LAMPF USERS GROUP PROCEEDINGS 139 Los Alamos National Laboratory 2. Hardware standards. The committee felt that we capabilities, should be able to handle tapes effec- should be moving toward 32-bit VAX-class ma- tively, and should serve as a convenient computing chines for data acquisition, primarily to solve the tool for the LAMPF community. However, it 16-bit address space problem with PDP-lls. The should be recognized that the DAC cannot committee also felt that LAMPF should begin necessarily satisfy all the needs of the Users and upgrading tape units to 6250/1600 bpi. that LAMPF should be willing to use other re- 3. Buffer processors. Michael Oothoudt presented to sources at this Laboratory, namely the Central the committee a simple idea for taking advantage of Computing Facility (CCF). the processing capabilities of the new machines 2. Problems. Two main problem areas were identified: without adding overhead from peripherals. The (1) unacceptable interactive response time on the basic idea is to ?ita:h multiple processors to a current systems, and central unit. As an event comes in, it is sent to the (2) inadequate disk space. first processor, the second event to the second, and These problems are being addressed. so on. Thus, the analysis of events would be carried 3. External networks. The committee recognized a on in parallel and increase the computing capacity need to provide convenient communications with of the central unit. other locations. Specifically, MP-1 should investi- 4. Data-acquisition sysiem Q. The committee identi- gate implementation of a network system such as fied a few Q projects that should be completed: for Telenet and should provide a convenient method to example, VAX data acquisition and documentation dial out of the DAC. This communication enhance- of internals of Q. However, they felt that the ment can, for example, facilitate distribution of Q programmers should not spend time adding drafts of papers. "bells and whistles" to Q but should direct their The TAP members had several comments and ques- efforts in more productive areas such as FASTBUS tions concerning this presentation. These questions are and buffer processors. listed here. 5. Networks. Networks to the experimental area are • Did the committee consider small (personal) com- long overdue and should be implemented with a puters as a standard for data acquisition? high priority. • Has parallel processing been considered for the Three topics were discussed under data analysis: (1) DAC? Data-Analysio Center (DAC) functions, (2) problems, • Has the committee properly considered options for and (3) external networks. Each of these areas is dis- the long term—specifically, writing data-acquisi- cussed below. tion systems in portable languages? 1. DAC functions. The committee discussed at some • Has the committee considered other standard oper- length the functions that the DAC can serve and ating systems, such as UNIX? those that should be addressed elsewhere. Specifi- These points will be brought up at the Long-Range cally, the DAC shouid provide interactive graphics Planning Committee meeting before the final report is prepared.

140 LAMP? USERS SKOUP PROCEEDINGS Novembar 1983 Los Alamos National Laboratory SUMMARIES OF RECENT LAMPF PROPOSALS

Exp. 808 0° EXCITATION FUNCTION FOR TCp-* n°n Los Alamos National Laboratory M. Cooper and D. Fitzgerald, Spokesmen

No summary available.

Exp. 809 STUDY OF tr,p AND n+,p REACTIONS WITH EPICS University of South Carolina G. S. Blanpied, Spokesman G. S. Adams, B. M. Preedom, C. S. Whisnant Universite de Neuchatel, Switzerland J.-P. Egger, Spokesman D. Bovet, E. Bovet, F. Goetz, P. Gretillat, C. Lunke, E. Schwarz University of Maryland N. S. Chant, B. G. Ritchie, P. G. Roos Massachusetts Institute of Technology R. Redwine, S. Gilad Michigan State University B. A. Brown, B. H. Wildenthal

The purpose of this study is to determine the selectivity of the (n~,p) reaction and, if it is as emphatic as the (p,n~) reaction, to investigate both the reaction mechanism properties and nuclear structure by determining the systematics for this reaction over a range of energies and nuclei.

November 1983 LAMPF USCBS GROUP PROCEEDINGS 141 Los Alamos National Laboratory Exp. 810 Test Channel.

Exp. 811

STUDY OF UNNATURAL-PARITY STATES IN NUCLEI USING LOW-ENERGY PIONS

University of Maryland B. G. Ritchie, Spokesman N. S. Chant, P. G. Roos Los Alamos National Laboratory R. L. Boudrie University of Colorado R. J. Peterson, J. J. Kraushaar University of South Carolina G. S. Adams, G. S. Blanpied, B. M. Preedom, C. S. Whisnant Virginia Polytechnic Institute and State University K. Gotow, M. Blecher

Unnatural-parity states in nuclei will be investigated using the low-energy pion channel and the LEP spectrometer. Initial studies will examine the excitation of the 1+ doublet in 12C, which has been well studied at resonance energies. Examination of the energy dependence of the excitation of these states should reveal important information about the pion-nucleus reaction mechanism for spin-flip transitions below resonance. If the results prove fruitful, other levels, such as the 0+ state in 6Li, will be studied. We have requested 216 h of beam time for the initial studies.

Exp. 812

BACK-ANGLE CHARGE ASYMMETRIES FOR ELASTIC n-DEUTERON SCATTERING

University of Colorado R. J. Peterson, Spokesman J. J. Kraushaar, T. G. Masterson, J. Mitchell, R. A. Ristinen, J. L. Ullmann Los Alamos National Laboratory R. L. Boudrie New Mexico State University G. R. Burleson, W. Cottingame

It is proposed to study the asymmetry between jt+ and n~ elastic scattering from the deuteron at angles beyond 120° for beam energies of 143 and 256 MeV on EPICS. These data will test current models of the mechanism for this simple reaction and aid in the determination of the limits of charge symmetry in the strong interaction.

142 LAMPF USERS GROUP PROCEEDINGS November1983 Los Alamos National Laboratory Exp. 813 PION CHARGE ASYMMETRIES FOR "C AT LOW BEAM ENERGIES ON THE LEP SPECTROMETER University of Colorado J. J. Kraushaar andR. J. Peterson, Spokesmen P. W. F. Alons, J. Mitchell, R. A. Risn'nen, J. L. Ullmann

It is proposed to measure the difference between n~ and n+ transition strengths to states in 13C at beam energies of 150, 100, 80, and 65 MeV, using the new LEP spectrometer system. Data will be obtained at one angle where the M4 cross sections are expected to be maximum. Positive pion data to the 4" state of 12C will be taken under the same circumstances and supplemented by a coarse angular distribution at one low energy. This ensemble of data will examine the changing reaction mechanism for a set of transitions known to exhibit both charge symmetry and huge asymmetries for pion scattering.

Exp. 814 ni-NUCLEAR ELASTIC SCATTERING FROM NICKEL AND TIN ISOTOPES AT ENERGIES BETWEEN 30 AND 80 MeV Virginia Polytechnic Institute and State University M. Blecher, Spokesman B. Fick, K. Gotow, D. Wright Los Alamos National Laboratory M. Hynes, Spokesman R. L. Burman, E. Piasetzky Oak Ridge National Laboratory F. E. Bertrand, E. E. Gross, F. Obenshain University of South Carolina G. Adams, G. Blanpied, C. S. Mishra, B. M. Preedom, C. S. Whisnant University of Maryland N. Chant, B. G. Ritchie, P. Roos We propose to measure elastic scattering of positive and negative pions from nickel and tin isotopes at energies of 30, 50, 65, and 80 MeV. We will use the new LEP spectrometer and cover the angular range from 20 to 140°.

November 1983 LAWF USERS GROUP PROCEEDINGS 143 Los Alamos National Laboratory Exp. 815

MEASUREMENT OF AN0, Asu AND ALh INpp AT 500, 580,650, 720, AND 800 MeV

Queen Mary College, London D. V. Bugg, Spokesman University of Surrey A. S. Clough, R. Shy pit Becffbrd College, London N. M. Stewart University of Texas P. J. Riley, K. H. McNaughton, C. Hollas Los Alamos National Laboratory B. E. Bonner, M. W. McNaughton, R. Silbar, J. C. Peng, U. Stein Rutgers University J. McGill University of California, Los Angeles G. Igo, G. Weston, B. Aas

3 3 3 The objective is a determination of the relative phases of the AW 'D2, F3, P2, and Pt amplitudes —• pnn+, and hence a definitive conclusion as to whether there are dibaryon resonances in these states. 3 Parameters ANO and ASL have great sensitivity to these phases; ALL is sensitive to the magnitudes of F3 and \P, amplitudes. The experimental setup will sample a large part of the phase space for the inelastic process.

Exp. 816

RADIAT W EFFECTS ON THE FIELD STRENGTH OF SAM, RIUM-COBALT PERMANENT MAGNETS

Los Alamos National Laboratory R. D. Brown, Spokesman C. F. Hansen, W. F. Sommer, J. R. Cost Arizona State University J. T. Stanley

Permanent magnets of nominal composition SmCo5 and Sm2Co17 will be neutron irradiated in the LAMPF spallation neutron flux to fluences of about 1 :< 1019n/cm2. The magnets will be mounted on rotating disks so that the decrease in field strength can be measured during the irradiation by reading the voltage generated in a pickup coil. Control samples will be maintained in an oven in which the temperature is kept equal to that of the irradiated sampler, to determine temperature-induced decreases in field strength.

144 LAMPF USERS GROUP PROCEEDINGS November 19B3 Los Alamos National Laboratory Exp. 817

I. ELASTIC SCATTERING OF POLARIZED PROTONS FROM 3H AT INTERMEDIATE ENERGY

University of California, Los Angeles A. Azizi, M. Bleszynski, and C. I go, Spokesmen B. Aas, D. Adams, E. Bleszynski, D. Lopiano, G. Pauletta, A. Wang, G. Weston, C. Whitten University of California, Los Angeles/Los Alamos National Laboratory K. Jones

We propose to measure the polarization transfer observables in the reaction p(3H,3H)/j at 800 MeV to obtain the selective information on the components of the 3H wave function and contributions from the spin components of the AW amplitudes describing this reaction. The data should allow a comparative study of proton scattering from 3He and 3H nuclei and may provide useful constraints on the studies of the properties of the three-body nuclear systems in terms of the quark model.

Exp. 818

PROTON DEUTERON ELASTIC SCATTERING AT 800-MeV TWO- AND THREE-SPIN OBSERVABLES University of California, Los Angeles G. Igo, Spokesman B. Aas, D. Lopiano, Y. Ohashi, G. Pauletta, F. Sperisen, G. Weston, C. A. Whitten, Jr. University of Minnesota H. Fujisawa, M. M. Gazzaly Los Alamos National Laboratory B. Bonner, M. McNaughton, S.-W. Xu National Laboratory for High-Energy Physics (KEK), Japan S. Isagawa, S. Ishimoto, A. Masaike Hiroshima University, Japan H. Hasai, F. Nishiyama Kyoto University, Japan A. Okihana University of Texas C. L. Hollas, K. H. McNaughton, P. Riley

The two- and three-spin elastic proton-deuteron observables, associated v .i L-, N-, and 5-type polarized 800-MeV proton beams, and a polarized spin-frozen deuterated target will be measured in the four-momentum transfer ranges: two-spin observables 0.25 < |/| <0.8-1.0 (GeV/c)2, three-spin observables 0.25 < t < 0.7 (GeV/c)2. These measurements will extend the measurements being made in HRS Exp. 685 0.04 < |f| < 0.3 (GeV/c)2 to large mon sntum transfer. Measurements at HRS at small 111 cover the recoil interval up to | /1 values where the deuterons emerge with substantial kinetic energy from the target cryostat

t^- > 0.075 GeV 2m -

November 1983 LAMPF USERS GROUP PROCEEDINGS 145 Los Alamos National Labor*'nrv These measurements will increase the number of observables measured over the entire range of interest, 0.04 < |/| < 0.7-1 (GeV/c)2, from 9 to 18 (Af-type target to 17). In principal, 23 independent observables are required to determine the scattering amplitude; experience with AW amplitudes indicates that more observables are required in practice. These data will provide valuable input for theoretical descriptions performed at UCLA and elsewhere, based on multiple-scattering theory, to determine the scattering amplitude, to gauge the sensitivity to noneikonal corrections, to test the AW amplitude at small \t\, to provide data to test three-body AW interactions, and to determine the sensitivity to subnuclear (quark) effects. The experiment will require the use of the EPB area beginning in 1984-85 for installation and tests of the polarized target. This measurement requires 1300 h of beam time, including tuneup, target polarizations, datr taking, and background measurements.

Exp. 819 II. ELASTIC SCATTERING OF POLARIZED PROTONS FROM 3H AT INTERMEDIATE ENERGY University of California, Los Angeles A.Azizi, M. Bleszynski, and G. Igo, Spokesmen B. Aas, D. Adams, E. Bleszynski, D. Lopiano, G. Pauletta, A. Wang, G. Weston, C. Whitten University of Calffbrnia, Los Angeles/Los Alamos National Laboratory K. Jones

We propose to measure the polarization transfer observables in the reaction p (3H,3H)p at 800 MeV to obtain the selective information on the components of the 3H wave function and contributions from the spin components of the AW amplitudes describing this reaction. The data should allow a comparative study of proton scattering from 3He and 3H nuclei and may provide useful constraints on the studies of the properties of the three-body nuclear systems in terms of the quark model.

146 LAMPF USERS GROUP PROCEEDINGS November 1983 Lor, Alamos National Laboratory Exp. 820

PION-INDUCED PION PRODUCTION ON 3He Los Alamos National Laboratory E. Piasetzky and P. A.M. Gram, Spokesmen D. MacArthur University of Wyoming G. A. Rebka, Jr., Spokesman D. Roberts Tel Aviv University J. Lichtenstadt, Spokesman J. Alster, D. Ashery, M. Moinester, S. A. Wood Colorado College C. Bordner Massachusetts Institute of Technology E. R. Kinney, J. L. Matthews

We intend to measure pion-induced pion production on 3He by detecting a pion of charge opposite to that of the incident beam in the reactions n+ 3Hc —*• n'X. Comparing the doubly differential cross sections for pion production in JHe to those previously measured in hydrogen (Exps. 99 and 337) and deuterium (Exp. 783) is expected to provide detailed information on the two-nucleon mechanism. These observations may reveal evidence for or against dynamical processes such as an intermediate AA state. Thus, study of the pion-production process is clearly important for understanding A propagation in the nucleus. The doubly differential cross sections for the above reactions will be measured at three incident energies spanning the region of A-resonance excitation. For each energy the cross section will be measured at 25-50 separate angle and momentum settings of the spectrometer that are chosen to produce a uniform mapping of the cross section in the center-of-mass frame. We plan to measure these cross sections with about 5% accuracy limited chiefly by systematic uncertainties and normalization. We will employ the same magnetic spectrometer and associated instrumentation that performed very well in similar measurements of n~p~* n+n~n in Exps. 99 and 337 and Tt*^—>• n^X in Exp. 783. This spectrometer-detector system combined with the P3 beam is extremely well suited to these measurements by the following properties: (1) fully usable P3 intensity; (2) thorough filtering of opposite charges; (3) small detectors to reduce backgrounds; (4) constant 15-msr acceptance and 9.5% momentum bite; (5) short flight path; and (6) reliable detection of pions in the momentum range from 50 to 325 MeV/c. Experience with the previous measurements gives us confidence that the spectrometer-detector system can also handle this measurement satisfactorily.

November 1983 LAMPF USERS GROUP PROCEEDINGS 147 Los Alamos National Laboratory Exp. 821

PION CHARGE EXCHANGE TO DELTA-HOLE STATES OF COMPLEX NUCLEI University of Colorado R. J. Peterson, Spokesman P. W. F. Alons, J. J. Kraushaar, J. Mitchell, R. J. Peterson, R. A. Ristinen, J. L. Ullmann Los Alamos National Laboratory H. W. Baer

Charge exchange to the delta excitation of complex nuclei is to be examined with n+ and n~ beams, 3 using the existing n° spectrometer moved to the P beam line. At 450 MeV, targets of CH2, CD2, C, Ca, Zr, and Pb are proposed for both charge states of the beam. A limited excitation function for n+ beams on

targets of CH2, CD2, and C will supplement the study. All reactions are to be observed at one angle, and + a coarse angular distribution for 450-MeV n on the CH2, CD2, and C targets will be measured.

Exp. 822

INELASTIC n+ AND n" SCATTERING ON 48Ca AT 50 AND 75 MeV

University of Colorado J. J. Kraushaar and J. L. Ullmann, Spokesmen P. W. F. Alons, J. Mitchell, R. J. Peterson, R. A. Ristinen University of Georgia E. R. Siciliano

It is proposed to measure the cross sections for the inelastic excitation of the 3.83-MeV 2+ state in 48Ca using n~ and rc+ beams with energies of 50 and 75 MeV. The main object cf the experiment is to check the reaction mechanism in the low-energy region where there is interference between s-wave and p-wave amplitudes in the non-spin-flip channels. The 3.83-MeV state in ^Ca was chosen because it exhibits the largest ratio of neutron-to-proton matrix elements and because a similar experiment was carried out in the resonance region.

Exp. 823 DEVELOPMENT OF AN (n.p) REACTION CAPABILITY AT AREA B OR BEAM LINE D Los Alamos National Laboratory N. S. P. King, P. Lisowski, and J. D. Bowman, Spokesmen G. L. Morgan University of Colorado J. Shepard, Spokesman D. A. Lind, J. L. Ullmann, C. D. Zafiratos Indiana University Cyclotron Facility C. D. Goodman University of Tel Aviv N. Auerbach

Success with recent measurements of the (p,n) reaction at the WNR Line D at 800 MeV and the observation of the isovector giant monopole resonance in (n~,n°) reactions generated a study of (n,p)

148 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory reaction capabilities at LAMPF. As the only viable alternative to the (K ,K°) reaction for AT7-AT= I transitions, the (n,p) reaction should be exploited for investigations of p-matrix elements, isovector giant resonances, and the question of A-hole effects in nuclear structure. The 7Li(«,/>) has been confirmed as an appropriate source reaction. Design sudies on a spectrometer and associated counting-rate estimates have been done using results from the (p,n) studies. All factors indicate that the facility can be built with adequate luminosity and resolution to open up an alternative reaction for charge-exchange nuclear excitations. This is primarily a proposal for a facility development in that it does not currently require beam-time allocation but does involve a commitment of resources from the magnet pool and shops for the fabrication and assembly. Count-rate estimates are made to give the level of beam-time commitments needed for future experiments.

Exp. 824 A STUDY OF LOW-ENERGY PION SCATTERING AS A PROBE OF NUCLEAR MAGNETIC DIPOLE EXCITATION Argonne National Laboratory H. E. Jackson, Spokesman D. F. Geesaman, M. Green, R. J. Holt, E. Ungricht, B. Zeidman

Basic simple features of pion scattering suggest that the use of pions to study Ml excitations will be most effective at the lowest experimentally convenient energies. Distorted-wave impulse approximation (DWIA) calculations support this conjecture. We propose to explore low-energy pion scattering as a probe of Ml excitations in a series of measurements predominately at 50 MeV using the targets 12C, S0Ti, 58Ni, "Zr, and 208Pb. The I2.7-MeV 1+ state in carbon is chosen as a benchmark case. The other targets are known to have substantial concentrations of Ml strength from studies of (p,p'% (e,e'), and (y,Y') reactions. The TIVJI" comparison will be used to study the isospin character of the resonances. The pion energy dependence will be used to establish the spin-flip character of the transitions. Good-quality pion- excitation spectra should shed light on recently reported discrepancies in the distribution of Ml transitions observed in (p,p') and (e.e') experiments. The expected energy resolution of the measurements will be 250 keV, which should be adequate to isolate the Ml structure as it has been observed in (p,p'). Measurements will be made at the Low-Energy Pion (LEP) channel using the new LEP pion spectrometer when it becomes operational.

Exp. 825 INVESTIGATION OF THE N& INTERACTION VIA n+d-*pn+n Rice University G. S. Mutchler, Spokesman S. D. Baker, J. A. Buchanan, J. M. Clement, M. D. Corcoran, I. M. Duck, J. W. Kruk, H. E. Miettinen, J. B. Roberts, Jr., G. C. Phillips University of Houston B. W. Mayes, L. S. Pinsky

We propose to study the reaction n+d-+ «A++ —» npn+ in a kinematically complete experiment. By a suitable choice of kinematics, the NA interaction in the final state can be emphasized, whereas other processes, such as quasi-free scattering and nN and NN final-state interactions, are suppressed. We propose to study the excitation function of A++ production at 6£m- = 55 and 90° for beam momenta ranging from 275 MeV/c (Vs = 2.17GeV) to 600MeV/c (y/s = 2.42 GeV), and the angular distributions of A++ production from 30° < 6^m' < 150° at \fs = 2.23 and 2.28 GeV. The excitation functions

November 1983 LAMPF USERS GROUP PROCEEDINGS 149 Los Alamos National Laboratory l 3 l will cover the proposed D2 (2.17-GeV), F3 (2.22-GeV), and G4 (2.43-GeV) dibaryon resonances. The angular distributions correspond to a complementary measurement ofyd-+pA°—*ppn~. In addition, it is proposed to check on a narrow anomaly observed in the yd —*• pvTp reaction at \/s = 2.23 GeV with a width of ~40 MeV. The isospin of the yd channel can be either T= 0 or 1, but that of the xd channel can be only T=l. The n+d—>-pn+n reaction will be studied in the same kinematical region as the yd experiment from 300 to 400 MeV/c (y's = 2.19 to 2.26 GeV) in steps of 12.5MeV/c. We will use the P3 beam line with a magnetic spectrometer in coincidence with a straight, time-of-flight arm.

Exp. 826 ISOSPIN DEPENDENCE OF NONANALOG PION DOUBLE CHARGE EXCHANGE

Los Alamos National Laboratory C. L. Morris, Spokesman University of Texas C. Fred Moore, Spokesman L. C. Bland, M. K. Brown, R. R. Kiziah, P. A. Seidl University of Pennsylvania R. Gilman, Spokesman H. T. Fortune, P. Kurt New Mexico State University G. R. Burleson, W. B. Cottingame

All measurements obtained of pion double-charge-exchange transitions for which J\ =J* = 0+ and AF=2 show a consistent set of features. Some recent data indicate an enhancement of T= 1 to T=3 transitions over F= 0 to F= 2 transitions. We propose to further investigate the isospin dependence of nonanalog double charge exchange by extending measurements to targets with greater neutron excess.

Exp. 827

STUDY OF ISOBARIC-ANALOG STATES IN PION SINGLE-CHARGE-EXCHANGE REACTIONS IN THE 300- TO 500 McV REGION Tel Aviv University J. Alster, Spokesman J. Lichtenstadt, M. A. Moinester, S. A. Wood Los Alamos National Laboratory H. W. Baer, E. Piasetzky, and U. Sennhauser, Spokesmen J. D. Bowman, M. D. Cooper, D. Fitzgerald, F. Irom, M. Leitch University of Colorado i. J. Kraushaar, G. Peterson, R. Ristinen, J. Ullmann Arizona State University J. R. Comfort George Washington University W. Briscoe

It is proposed to measure (n \;i0) cross sections to isobaric-analog states (I ASs) at angles from 0 to 10° on targets 7Li, 14C, 60Ni, 90Zr, 120Sn, and 208Pb. Beam energies will be 300, 375, 450, and 500 MeV. The ;

ISO LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory nucleonic cross sections for n p —>• ir°« will also be measured at the same angles and energies. The proposed measurements are the first of their kind at energies above the A(3,3) resonance. In the 300- to 500-MeV region, the ratio isovector (AT= l)/isoscalar (AT=0) of interaction terms in the nN system reaches its largest value. The proposed measurements constitute the most direct determination of the AT= 1 term in the 7r-nucleus interaction. Also, this proposal extends the investigation performed in the 100- to 300-MeV region, where remarkably regular patterns were found for the 0° cross sections. A major motivation is to see if these patterns are continued into the higher energies.

Exp. 828 TOTAL AND DIFFERENTIAL CROSS SECTIONS FOR n+d—pp BELOW 20 MeV Virginia Polytechnic Institute and State University K. Gotow, Spokesman M. Blecher, B. I. Fick, D. Wright University of Virginia R. C. Minehart, Spokesman G. Das University of Maryland B. G. Ritchie, Spokesman N. S. Chant, P. G. Roos University of South Carolina G. S. Adams, G. S. Blanpied, B. M.' Preedom, C. S. Whisnant

The total and differential cross sections for n+d^>-pp will be measured at .hree energies: 5, 10, and 15 MeV. Uncertainties will be reduced to less than 5% for the total cross section. The low-energy beams will be developed by transporting a 16- to 20-MeV pion beam to the center of the Low-Energy Pion (LEP) channel, degrading the beam in energy at the channel midplane, and transporting the lower energy beam to the exit of the channel. Final degradation to the desired energy will be accomplished within the LEP cave using a multi-element scintillator hodoscope. This method should result in a pion beam with very small positron and tnuon contamination and low-energy spread (less than 2 MeV). The results from this experiment will provide a check on the only measurements available for the energy dependence of the total cross section (those by Rose) that possess large absolute uncertainties, and will bear directly on the theoretical predictions for s-wave pion production at very low energies. We request 91 shifts of beam time in the low-energy pion channel, in two phases of 50 and 41 shifts.

Exp. 829 A MEASUREMENT OF THE WIDTH AND POSITION OF THE A++ RESONANCE IN eLi AND I2C University of Virginia K. Ziock, Spokesman G. Das, J. R. Hurd, R. C. Minehart We propose to measure the quasi-free n*,n+p scattering cross section on 12C and 6Li. The aim of the experiment is to determine whether or not the A++ resonance is changed as to energy or width when the (n+p) interaction takes place in a nucleus. The special feature of the experiment is the elimination or at least reduction (in the case of 6Li) of the energy dependence of the initial- and final-state interaction through a judicious choice of the kinematics. To ensure the quasi-free nature of the interaction, only those events will be selected that lead to a discrete final state.

November 1983 LAMPF USERS GROUP PROCEEDINGS 151 Los Alamos National Laboratory Exp. 830

THE REACTION (n,np) ON 3He AND "He AT ENERGIES ABOVE THE (3,3) RESONANCE University of Virginia R. Minekart, Spokesman C. Smith, L. Orphanos, G. Das, R. Whitney Los Alamos National Laboratory P. A. M. Gram Argonne National Laboratory D. Geesaman, R. J. Holt, H. Jackson, B. Zeidman, J. Schiffer Northwestern University S. Levenson, R. Segel

The differential cross section for the (n,np) reaction in JHe and 4He will be measured at energies of 350, 400, and 475 MeV at angles of 60, 90, and 120°. The scattered pions will be detected in the large- aperture spectrometer (LAS) in the P3 beam in coincidence with the protons detected in an array of scintillation counters. The results will be used to confirm measurements of inclusive scattering from Exp. 513 and will provide new detailed measurements on the exclusive pion-knockout reaction at energies above the strong (3,3) resonance. The data will be analyzed in the framework of the impulse approximation as a starting point for understanding the interaction. If the experiment is run in conjunction with a similar experiment (Exp. 628) at lower energy, no setup time would be required.

Exp. 831 THE [n+,p(pp)\ REACTION ON LIGHT NUCLEI

College of William and Mary C. F. Perdrisat, Spokesman H. O. Funsten, V. Punjabi University of Virginia R. Minehart, Spokesman G. Das, P. C. Gugelot, L. Orphanos, R. Whitney Los Alamos National Laboratory P. A. M. Gram George Mason University J. Lieb

An experiment is proposed to look for manifestations of a final-state interaction between a A and one or several nucleons. The nuclear targets will be 6Li and 7Li in a first phase, and 3He and 4He in a second phase. The kinematics is chosen so as to enhance the probability fhat the first proton be the signature of the excitation of a A, and the two other protons, the signature of the interaction of the A with a nucleon in A/V—>-AW. The result will bear on the question of the existence of bound isobar-multinucleon states and determine their invariant masses and decay rates. Particularly interesting may be the observation of a ANNN state, which we propose to search for in the reaction 6Li[n+ ,a\pp)}.

152 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Exp. 832 GAMMA-RAY ANGULAR CORRELATION FROM i2C(p,/>')I2C*(15.11 MEV) George Mason University B.J.Lieb, Spokesman Collge of William & Mary C. F. Perdrisat and H. O. Funsten, Spokesmen Rutgers the State University of New Jersey C. Glashausser Florida State University H. S. Plendl Technical University of Zurich, Switzerland E. Hermes

This is a proposal for running time on the EPB beam at LAMPF at a proton energy of 500 MeV to do gamma-ray angular correlation between the decay gamma from the 15.11-MeV 1+, T= 1 level in !'C and the momentum transfer direction, q. By the use of incident protons polarized in specific directions the angular correlation will yield information on several parts of the NN effective interaction and the nuclear transition densities. Because of the lack of gamma feeding from higher levels, the protons can be observed with a coincidence scintillator telescope arrangement.

Exp. 833 CONTINUATION OF THE INVESTIGATION OF LARGE-ANGLE PION NUCLEUS SCATTERING New Mexico State University G. R. Burleson, Spokesman W. B. Cottingame Los Alamos National Laboratory S. J. Greene University of Texas C. Fred Moore, M. Brown, R. Kiziah, C. Milner, D. Oakley, P. Seidl University of Minnesota D. Dehnhard, C. Blilie, M. Garakani, S. Seestrom-Morris

Investigation of pion-nucleus scattering in the backward hemisphere was begun at EPICS with Exp. 681. For that experiment, we initiated the design, construction, and testing of a modification of the EPICS system that facilitated measurements of pion-nucleus scattering between 115 and 180°. The work was carried out with major contributions from Groups MP-10, MP-8, MEC-2, and the LAMPF and New Mexico State University shops. The tuneup and initial data taking with the new apparatus were successfully carried out in late summer 1983. Even though we received only ~3/4 the total time allotted to us by the PAC because of external problems, we were able to make a full checkout of the system, verifying that it performed essentially as expected, and to accumulate an acceptable amount of useful data. We propose continuation of the work begun in Exp. 631, that is, to study the systematics of pion- nucleus scattering at large angles. Thp situation as described in Proposal 681 is essentially unchanged; the behavior of large-angle pion-nucleus scattering is still poorly known from an experimental point of view, and poorly understood from a theoretical point of view. The models of the pion-nucleus interaction discussed in that proposal describe elastic and inelastic scattering well over the angular range for which

November 1983 LAMPF USERS GROUP PROCEEDINGS 153 Los Alamos National Laboratory data are abundant (out to ~120°), but diverge drastically for larger angles. A realistic description of pion- nucleus scattering requires ample data in the backward hemisphere to constrain the calculations and reveal the systematics of that region. We are therefore proposing continuations of measurements of both angular distributions and excitation functions at 180° for targets for which there are now sufficient data at forward angles. Such a body of data should prompt serious theoretical investigation.

Exp. 834 THE PION-NUCLEUS INTERACTION STUDIED WITH THE 4/-» 3d TRANSITION OF RARE-EARTH PIONIC ATOMS Purdue University Y. Tanaka andR.M. Steffen, Spokesmen Los Alamos National Laboratory E. B. Shera, Spokesman M. V. Hoehn, W. Reuter University of Wyoming A. R. Kunselman Princeton University J. D. Zumbro

It is proposed to measure the x-ray energies and widths of the pionic 4/—• 3d transitions (M x rays) of 160Gd, 180Hf, 186W, and I92Os. Because of the strong absorption of the pion by the nucleus, the 3d orbit is the lowest level observed in rare-earth pionic atoms, and the strong-interaction energy . lifts (e = 11-23 keV) and widths (F = ll-43keV) of the Ms rays of these atoms can provide an important constraint on the optical-model description of the pion-nucleus interaction for pionic atoms in the A = 160-190 mass region.

Exp. 835 TARGET MASS DEPENDENCE OF THE ISOVECTOR CONTRIBUTION TO THE GIANT QUADRUPOLE RESONANCE University of Minnesota S. J. Seestrom-Morris, Spokesman S. Nanda, D. Dehnhard Los Alamos National Laboratory C. L. Morris, T. A. Carey, J. M. Moss, N. S. P. King, D. Drake University of Texas C. F. Moore, L. C. Bland University of Colorado J. Ullmann

We propose to measure cross sections for excitation of the giant quadrupole resonance (GQR) in 138Ba and 238U using K+ and K~ scattering at 162 MeV. Measurements of n+ and n~ scattering to the GQR in 40Ca, u8Sn, and 208Pb have shown that the ratio of the neutron to proton matrix elements MjMv is a steadily increasing function of A, and that the increase is faster than predicted by the hydrodynamical model. The present experiment is intended to extend the A dependence to a heavier target, 238U, and to add a target intermediate ir> mass to tin and lead.

154 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Exp. 836

ENERGY DEPENDENCE OF PION SCATTERING TO THE GIANT RESONANCE REGION OF M8Pb University qf Minnesota S. J. Seestrom-Morris, Spokesman S. Nanda, D. Dehnhard, N. M. Hintz Los Alamos National Laboratory C. L. Morris, T. A. Carey, J. M. Moss, N. S. P. King, D. Drake University qf Texas C. F. Moore, L. C. Bland University of Colorado J. Ullmann

We propose to measure n+ and n~ scattering to the giant resonance region of 208Fb at incident pion energies of 120, 200, and 230 MeV. These measurements are intended to help us understand the anomalously large ratio R = a(n~)/a(n+) observed for the giant quadrupole resonance with 162-MeV pions. If the large ratio is the result of actual differences in the number of protons and neutrons contributing to the transition, then measurements off resonance should yield the same value of R as previously measured on resonance.

Exp. 837 MEASUREMENT OF SPIN-FLIP CROSS SECTIONS UP TO 40-MeV EXCITATION IN 58Ni AND 90Zr

Rutgers University C. Glashausser and S. Nanda, Spokesmen F. DeAngelis, J. McGill Los Alamos National Laboratory T. Carey, K. Jones, J. McClelland, J. Moss University of Minnesota M. Franey, M. Gazzaly, N. Hintz, S. Seestrom-Morris

A large spin-flip cross section has been observed in Exp. 660 at excitation energies up to 25 MeV in 90Zr at 3.5°; data at 5°. which extend only to 16 MeV, are similar. This is the first observation of spin- excitation strength above the MX resonance. It is proposed to extend these measurements to 40 MeV with good statistics in excitation-energy bins 2-MeV wide (three magnet settings). The measurements will be carried out on 58Ni and 90Zr. over the angular range from 3 to 9° in 2° steps. The results should provide the first definitive measure of the spreading of spin-excitation strength in nuclei and some indication of the orbital angular momentum transfers involved.

November 1983 LAMPF USERS GROUP PROCEEDINGS 135 Los Alamos National Laboratory Exp. 838

PION-INDUCED PION PRODUCTION ON NUCLEI AT 400 MeV

Los Alamos National Laboratory M. J. Leitch and E. Piasetzky, Spokesmen R. S. Bhalerao, B. J. Dropesky, G. C. Giesler, L-C. Liu, Y. Ohkubo, C. J. Orth, P. A. M. Gram Tel Aviv University D. Ashery, J. Lichtenstadt, S. A. Wood

Recently, a series of measurements of pion-ir.duced pion production has been made on the deuteron (Exp. 783). Together with earlier measurements of pion production in tiN collisions, these studies have established the systematics of n~p —»• n~n+n and n~d —*• Jt+ (n"nn). In the meantime, we have measured by activation techniques the total cross sections of the (n,2n) reactions in nuclei 27A1,4SSc, S1V, and 63Cu, leading to all particle stable states (Exp. 730). The obvious question that still remains following the proton and deuteron measurements is what happens to the total (inclusive) pion-production cross section when this basic interaction is embedded in a larger nucleus. Any multinucleon reaction mechanisms that can contribute to pion-induced pion production should be apparent in the systematics of the differential cross sections. A comparison of the nuclear with the free-nucleon cross section should indicate how the free process is modified in a nucleus and whether more complex reaction mechanisms are involved. In previous experiments on the proton and the deuteron, double charge exchange was not possible, so it was sufficient to observe only the outgoing pion of opposite charge, that is, as in the channel n+A —>• K+n'A'. For pion production on a nucleus, it is necessary also to observe the second pion to distinguish pion production from pion double charge exchange. We propose to measure the differential cross section for the reaction 12C(7t+,jt+n") at 400 MeV using two large solid-angle, large-momentum-bite spectrometers in coincidence.

Exp. 839

PION INELASTIC SCATTERING FROM THE 1+ DOUBLET IN nC

University of Texas C. F. Moore, Spokesman L. C. Bland, P. A. Seidl, R. R. Kiziah Los Alamos National Laboratory C. L. Morris, Spokesman University of Minnesota D. Dehnhard, S. J. Seestrom-Morris University of Pennsylvania R. Gilman, P. Kutt, H. T. Fortune New Mexico State University W. B. Cottingame

12 We propose to measure o(9) for the reaction C(;t,jt') at three energies: Tn = 120, 180, and 230 MeV. Special emphasis will be placed on obtaining good statistics data for the (l+,0) and (1+,1) states at 12.71 and 15.11 MeV. These data will provide further information about the anomalously large cross sections for exciting the 15.11-MeV state at incident pion energies near 180 MeV.

156 LAMPF USERS GROUP PROCEEDINGS November19B3 Los Alamos National Laboratory Exp. 840

INELASTIC PION SCATTERING FROM 16O

AT Tn = 120 AND 200 MeV University of Texas, Austin L. C. Bland, Spokesman C. F. Moore, P. A. Seidl, R. R. Kiziah University of Pennsylvania H. T. Fortune, Spokesman R. Gilman University of Minnesota S. J. Seestrom-Morris, D. K. Dehnhard Los Alamos National Laboratory J. J. Kelly, C. L. Morris

We propose to measure i6O(rz+,n+') angular distributions to the low-lying, natural-parity excited states

at two incident beam energies: Tn = 120 and 200 MeV. These measurements will complement existing

data at Tn = 164 MeV, thus providing information about a variety of higher-order contributions to pion

inelastic scattering near the A33( 1232 MeV) resonance. In particular, the energy dependence of the magnitudes and shapes of the angular distributions should provide information about the role of coupled- channels effects, second-order contributions to the pion-nucleus optical potential, and possible density- dependent renormalizations of the pion-nucleus interaction.

Exp. 841

FORWARD-ANGLE PION INELASTIC SCATTERING ON LIGHT NUCLEI

University of Texas, Austin L. C. Bland and C. F. Moore, Spokesmen P. A. Seidl, R. R. Kiziah University of Pennsylvania H. T. Fortune, Spokesman R. Gilman University of Minnesota S. J. Seestrom-Morris Los Alamos National Laboratory C. L. Morris

We propose to measure forward-angle pion inelastic scattering from a series of light targets (4He, 9Be, I6O, 20Ne, J4Mg, "S, '"'Ca) to help establish the existence of the spin-flip El giant resonance. This systematic study should help to distinguish between assignments for these forward-peaking angular distributions of either monopole or spin-fip E1 t trength.

November 19B3 LAMPF USERS GROUP PROCEEDINGS 157 Los Alamos National Laboratory Exp. 842

u.SR SHIFT AND RELAXATION MEASUREMENTS IN ITINERANT MAGNETS

Tata Institute, India L. C. Gupta, Spokesman Los Alamos National Laboratory R. H. Hejfner, Spokesman D. W. Cooke, R. L. Hutson, M. Leon, M. E. Schillaci, J. L. Smith University of California, Riverside D. E. MacLaughlin, Spokesman Texas Tech University C. Boekema Rice University S. A. Dodds Hebrew University, Israel N. Kaplan

The proposed work uses muon spin rotation (uSR) and relaxation to examine local electronic structure and thermal fluctuations in transition-metal compounds that exhibit exchange-enhanced itinerant magnetism. The following local properties of such compounds are accessible via uSR: (1) the magnitude of the conduction-electron spin polarization at the interstitial sites; (2) the extent to which this local interstitial polarization is proportional to the bulk magnetization; (3) zero-field critical dynamic behavior of spin fluctuations in compounds that magnetically order at a nonzero transition temperature; and (4) specific temperature dependences of the muon spin-lattice relaxation rate, which are predicted by the self- consistent renormalized (SCR) theory of itinerant-electron magnetism. A number of specific compounds

will be studied. ZrZn2 is a weak ferromagnet (Tc ~ 19 K, us =; 0.12 uB), in which neutron scattering suggests strong interstitial conduction-electron spin polarization; uSR measurements will corroborate

this, and in addition permit zero-field studies of critical dynamics around Tc. Studies of the pseudobinary

alloys (Zr,Hf)Zn2 and (Zr,Ti)Zn2 will test some specific predictions of the SCR theory of these

compounds. In Mn,_xFexSi, magnetic order disappears at x=;0.2, so that local spin-fluctuation phenomena can be studied in paramagnets and ordered magnets within the same alloy system. In TiBe^Cu,,, exchange-enhanced paramagnetism is very large for x = 0, but the magnetic order suggested by neutron scattering tor x > 0.16 has no apparent effect on the specific heat. The nSR measurements would be helpful in determining whether magnetic order indeed sets in with increasing copper concentration.

158 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Exp. 843

A SEARCH FOR A3_3 COMPONENTS OF GROUND-STATE NUCLEAR WAVE FUNCTIONS Los Alamos National Laboratory C. L. Morris, Spokesman R. L. Boudrie University of Texan C. F. Moore, Spokesman L. C. Bland, P. A. Seidl, R. R. Kiziah University of Minnesota D. Dehnhard. S. J. Seestrom-Morris University ofPennsylvc, 'ia R. Gilman, P. Kutt, H. T. Fortune New Mexico State University W. B. Cottingame, G. R. Burleson Rutgers University J. A. McGill, C. Glashausser

We propose to search for the reaction wO(n+,TCp). Pions will be detected using the EPICS spectrometer and protons will be detected in a scintillator telescope to be mounted in the scattering chamber. The kinematics will be constrained to be those expected for the quasi-free reaction (n+,K+p). A significant cross section for this process will indicate a one-step mechanism for the double-charge- exchange reaction. Estimates using a simple data-to-data model for this process indicate it should be possible to place a limit on the probability of finding A in the nuclear wave function on the level of 10~5.

Exp. 844

MEASUREMENT OF ANN,ASS, AND^LS FOR THE REACTION pp -+p + n + n+ AT 800 MeV University of California, Los Angeles G. Pauletta, Spokesman. B. Aas, G. Igo, Y. Ohashi, G. Weston, C. Whitten University of Minnesota M. Gazzaly, Spokesman N. M. Hintz, H. Fujisawa Los Alamos National Laboratory N, Tanaka, Spokesman K.Jones, C. Morris, J. McClelland, S. Greene Hiroshima University, Japan H. Hasai National Laboratory for High-Energy Physics (KEK), Japan S. Isagawa, S. Ishimoto, A. Masaike

+ We propose to measure ,4NN, ,4SS, and ASL for the reaction pp —• p + n + n at 800 MeV. The experiment makes use of the HRS, the 5-type polarized target, and associated experimental equipment to be used for Exps. 709 and 790. We will take advantage of the good momentum and angular resolution of the HRS to eliminate background. The experimental arrangement for Exps. 709 and 790 will he augmented by a system of multiwire proportional chambers and counters designed to detect the pion. The momentum of the pion will be analyzed in the field of the superconducting solenoid. The proton will be

November 1983 LAMPF USERS GROUP PROCEEDINGS 159 Los Alamos National Laboratory detected in the HRS. We will study the region of phase space corresponding to pion production with missing mass approaching that of the conjectured 'Z>2 dibaryon resonance. Observation of missing-mass- dependent structure would constitute the most direct evidence in favor of such a resonance.

Exp. 845 PION INELASTIC SCATTERING FROM 9Be Los Alamos National Laboratory J. J. Kelly, Spokesman C. Morris University of Texas L. Bland Massachusetts Institute of Technology W. Bertozzi, J. M. Finn, C. Hyde-Wright, P.. Lourie

We propose to measure differential cross sections for the excitation of 'Be by n+ and n~ in the momentum transfer range between 0.5 and 2.5 fin"1, with particular emphasis upon the broad low-lying states. Many of these states have previously been studied with (e,e') and (p,p'). A careful line-shape analysis of the continuum has revealed well-defined broad states not previously known. These states are important to the understanding of the structure of'Be, a highly deformed system exhibiting both valence neutron transitions and collective alpha clustering phenomena. The unique isospin selectivity of pion scattering near resonance will be exploited to determine the neutron-like and the isoscalar (alpha-like) content of these various states of 'Be. Because some of the states of interest are broad and have relatively small cross sections, approximately 250 h of beam time at EPICS will be required.

Exp. 846 NN^-NNn: CROSS SECTIONS AND ANALYZING POWERS FOR THE 800-MeV pp ->- n+{np) AND pn -*- n~{pp) INCLUSIVE REACTIONS Texas A&M University :'f. S. Bhatia and G. Glass, Spokesmen •J. C. Hiebert, R. A. Kenefick, S. Nath, L. C. Northcliffe Los Alamos National Laboratory E. Colton, S. Greene, R. R. Silbar New Mexico State University G. Burleson, W. Cottingame Rutgers University J. A. McGill University of Montana R. H. Jeppesen Washington State University G. E. Tripard Rice University G. S. Mutchler, P. Pancella

We propose to measure cross sections and analyzing powers for the 800-MeV#p —»• jt+ (np) and/in —>• n (PP) inclusive reactions. We propose to cover the range from ~300 MeV/c to the maximum pion momentum at two angles. Liquid-hydrogen and -deuterium targets at the HRS will be used.

160 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Exp. 847 A PRECISION TEST OF NUCLEAR CHARGE SYMMETRY Texas A&M University T. S. Bhatia andJ. C. Hiebert, Spokesmen G. Glass, R. A. Kenefick, S. Nath, L. C. Northcliffe Los Alamos National Laboratory D. H. Fitzgerald, J. J. Jarmer New Mexico State University G. Burleson University of Montana R. H. Jeppesen Washington State University G. E. Tripard

We propose to measure the asymmetries for 800-MeV np and np elastic-scattering processes near 75° cm. We will scatter 800-MeV polarized neutron beam (n-type, polarization ~0.50) from a polarized proton target (n-type, polarization ~0.80) and extract np and tip asymmetries from a truly simultaneous measurement, thereby eliminating many types of systematic errors. From the measured asymmetries, zero-crossing angles 60(np) and 80(np) will be obtained. We will aim for an accuracy of better than 0.1 ° for each 0O, the comparison of which constitutes a test of nuclear charge symmetry.

Exp. 848 IN-FLIGHT ABSORPTION OF LOW-ENERGY NEGATIVE PIONS Los Alamos National Laboratory Y. Ohkubo, Spokesman B. J. Dropesky, G. C. Giesler, M. J. Leitch, L.-C. Liu, C. J. Orth

We propose to measure by activation techniques the ratio of the yields of the two-nucleon-out products, 15-h 24Na from an nn out and 3.4-min 24Ne from an np out, following the absorption of ~15- MeV jt" in 26Mg targets. The objective is to test a model-dependent calculated ratio of the probability for 7i~ absorption on an np vs app pair in a nucleus at low energies. This ratio shows a sharp drop in going from zero pion kinetic energy to ~30 MeV.

November 7983 LAMPF USERS GROUP PROCEEDINGS 161 Los Alamos National Laboratory Exp. 849 A. MEASUREMENT OF THE DIFFERENTIAL CROSS SECTION FOR iCp -* n°n AT 0° AND 180° IN THE MOMENTUM REGION 471-687 MeV/c B. TEST OF ISOSPIN INVARIANCE IN JIAT SCATTERING AT 180° IN THE MOMENTUM REGION 471-687 MeV/c Los Alamos National Laboratory D. H. Fitzgerald, Spokesman H. W. Baer, J. D. Bowman, M. D. Cooper, N. S. P. King, E. Piasetzky, J. C. Peng, N. Stein George Washington University W. J. Briscoe, Spokesman M. F. Taragin Abilene Christian University M. E. Sadler, Spokesman Catholic University of America D. I. Sober Tel Aviv University M. A. Moinester

We propose to measure differential cross sections for nN scattering at angles near 0 and 180° at momenta where measurements of the cross sections and analyzing powers at intermediate angles already exist: 471, 547, 625, 657, and 687 MeV/c. Measurements of n~p —*• n°n will be made in the cm. intervals 0-40° and 150-180° in order to overlap the existing measurements. Differential cross sections for n^p elastic scattering will be measured at 180°. The real part of the nN forward-scattering amplitude can be obtained from an analysis of 0° charge-exchange cross sections and ^p total cross sections; comparison to the results of forward-dispersion relations will provide an excellent test of the assumptions used in evaluating the dispersion relations. Charge-exchange measurements at both forward and backward angles are needed in partial-wave analyses to determine the contributions of higher partial waves and for dispersion-relation constraints. Data of high precision are almost completely lacking for forward charge- exchange scattering; at backward angles no systematic study has been made of the angular behavior of the cross sections. The measurement of cross sections for •xrp elastic scattering and n~p—* n°n at 180° will allow a model-independent test of isospin invariance in a momentum region where the lower isospin bound in the nN system is predicted to be saturated. The measurements can all be carried out using existing detectors, which are highly suited to the experiment: the JT° spectrometer will be used for the charge-exchange measurements and the Large-Aperture Spectrometer for elastic scattering. We are proposing the two experiments jointly, even though they require two separate detection systems, because the rationale for the elastic-scattering measurements at 180° depends on the existence of charge-exchange data at identical momenta.

162 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Exp. 850

STUDY OF THE MASS AND ENERGY DEPENDENCE OF LOW-ENERGY PION SINGLE CHARGE EXCHANGE AT 0°

Los Alamos National Laboratory F. Irom and M. J. Leitch, Spokesmen H. W. Baer, J. D. Bowman, M. D. Cooper, E. Piasetzky, U. Sennhauser, B. J. Dropesky, G. C. Giesler, Y. Ohkubo University of Colorado J. J. Kraushaar, R. A. Ristinen, J. L. Ullmann

We propose to measure the energy dependence of the 0° pion single-charge-exchange cross section to the isobaric-analog state for 1!N, 39K, and 120Sn, at pion energies between 35 to 70 MeV. At low energies the energy dependence of the deep minimum in the 0° cross section should help to illuminate the nature and importance of second-order effects such as true pion absorption and the Lorentz-Lorenz effect.

Exp. 85J

SEARCH FOR RECOIL-FREE A PRODUCTION AND HIGH-SPIN STATES IN THE 2O8Pb(p,r)2O6Pb REACTION AT£; a 400 MeV

University of Minnesota N. M. Hintz, Spokesman D. Cook, M. Franey, H. Fujisawa, S. J. Seestrom-Morris Los Alamos National Laboratory C. L. Morris Rutgers University C. Glashausser, J. McGill

We propose to search for recoil-free A production (q ~ 0) in the (p,f) reaction on 108Pb. This reaction satisfies the momentum transfer requirements for the production of a low-spin (N~3A) collective resonance in nuclei. As secondary objectives, we wish to study the excitation of high-spin pair-hole states at low excitation, and the high multipole components of the deep pair-hole function. The experiment will be done at the HRS. Because currents of =:5O-7O IL4 are required for the highland deep-hole region, we must use the unpolarized beam for this part The A region could be done with either polarized (any direction) or unpolarized bcm.

November 1983 LAMPF USERS GROUP PROCEEDINGS 163 Los Alamos National Laboratory Exp. 852

MEASUREMENTS OF (n*^) REACTIONS ON NUCLEAR TARGETS TO STUDY THE PRODUCTION AND INTERACTION OF n MESONS WITH NUCLEI

Los Alamos National Laboratory J. C. Peng, Spokesman H. W. Baer, T. A. Carey, D. M. Drake, D. H. Fitzgerald, P. A. M. Gram, M. J. Leitch, T. K. Li, J. M. Moss, N. Stein, J. W. Sunier University of Virginia R. R. Whitney We propose to study the production of T| mesons and their interactions with nuclei by measuring (JI^TI) reactions on nuclear targets. The n° spectrometer will be used to detect etas by their r| —• 2y decay mode. In the initial stages of calibrating and setting up the experiment on the P3 beam line, thep{n',r\)n reaction

will be measured on a CH2 target at 700 MeV/c where the cross section is known. After demonstrating the feasibility of n, production and detection from hydrogen, the (Ji+,n.) reaction will be measured at 0° on a series of solid targets from 7Li to 120Sn at incident momenta of 620 and 680 MeV/c. The aim of these measurements is to study the reaction mechanism for production of etas and to deduce information about the Ti-nucleus interaction from the selectivity, mass dependence, and energy dependence of the reactions. A close comparison will be made with existing (JI+,JI°) data to search for any connection between the (n+.r,) and (n+,n°) reactions. Differences as well as similarities between the n° and r\ mesons make the comparison of the two reactions an interesting but open question. If charge exchange plays an important role in the (n+,r\) reaction, then selective population of isobaric-analog states would be expected. Alternatively, there may be some other coherent process that governs r\ production from nuclei such as occurs in the coherent production of pions. We also propose to measure angular distributions for the two reactions }He(n~,T\)t and 7Li(7t+,r|)7Be, which should provide additional information on the r|-nucleus interaction. Another phase of this proposal is to measure the 3He(n~,t)r\ reaction by detecting forward- angle tritons in the Large-Aperture Spectrometer. This measurement corresponds to large-angle n production, and by combining with the forward-angle data from the (TC,T\) reaction, a complete angular distribution from 3He would be obtained. If the n° spectrometer were not immediately available for n, detection, we would propose to begin these experiments with the triton detection phase.

Exp. 853 MEASUREMENT OF WOLFENSTEIN PARAMETERS AT 650 MeV, AND da/dQ AT 500, 650, AND 800 MeV FOR pd~*pd ELASTIC SCATTERING

University of California, Loa Angeles G. S. Weston and G. J. Igo, Spokesmen B. Aas, D. Adams, A. Azizi, E. Bleszynski, M. Bleszynski, D. Lopiano, G. Pauletta, F. Sperisen, A. T. M. Wang, C. A. Whitten

We will measure Dss, DSL, DLL, DLS, and Ay for pd —>- pd elastic scattering at 650 MeV for lab angles 3-36°. We will also measure da/dQ from 3-36° for pd -* pd elastic scattering at 500, 650, and 800 MeV. The measurements will be done in Line C at the HRS using a LAMPF liquid-deuterium target for the

Wolfenstein parameters and a CD2 target for the cross-section measurements.

164 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Exp. 854

MUON SPIN RESEARCH IN OXIDE SPIN GLASSES Texas Tech University C. Boekema, Spokesman R. L. Lichci Los Alamos National Laboratory D. W. Cooke, Spokesman R. H. HefTher, R. L. Hutson, M. Leon, M. E. Schillaci Technical University, Eindhoven V. A. M. Brabers University of Wyoming A. B. Denison Rice University G. A. Gist, S. A. Dodds University of California, Riverside D. E. MacLaughlin

The muon-spin-rotation (uSR) technique will be used to study dynamical spin processes and internal magnetic-field distributions in select oxide spin glasses. Because for temperatures below room temperature the muon site in magnetic oxides is rather well known, the muon can be used as a powerful magnetic probe in the interstitial regions to investigate spin dynamics and ordering phenomena in oxide spin glasses. Initial uSR studies are planned on Fe-Ti and V-Ti oxide systems, b Mil of which exhibit interesting anisotropic spin-glass behavior.

Exp. 355

MEASUREMENT OF 2MPb-208Pb GROUND-STATE NEUTRON DENSITY DIFFERENCE

University of Minnesota N. Hintz, Spokesman D. Cook, M. Franey, M. Gazzaly, H. Fujisawa University of Texas G. Hoffmann, M. Barlett Los Alamos Motional Laboratory J. Amann

We propose to make a precision measurement (< ±0.5%) of the ratio of the differential elastic- scattering cross sections of 206Pb to 208Pb over a range of q =: 0.3 to 3.5 frrr1 at any proton energy from 650 to 800 MeV. These data, together with charge densities from electron scattering, will enable us to extract the neutron density difference to high accuracy. The purpose is to test the most recent many-body calculations (DDHFB) of the proton and neutron density differences. The neutron difference, being of first order in the nei'tron number, is much larger (~ xlO) than the proton difference. Thus this quantity must be measured to test the validity of the theory. The experiment will be done at HRS with standard equipment At forward angles, either a polarized or unpolarized beam can be used; at large angles, the unpolarized beam intensity is required. A total of 36 h of either polarized or unpolarized beam and 60 h of unpolarized beam is requested.

November 1983 LAMPF USERS GROUP PROCEEDINGS 165 Los Alamos National Laboratory Exp. 856

COMPARISON OF DOUBLE CHARGE EXCHANGE AND INCLUSIVE SCATTERING IN 3He

Los Alamos National Laboratory P.A.M. Gram, Spokesman D. W. MacArthur, E. Piasetzky Massachusetts Institute of Technology J. L. Matthews, Spokesman E. R. Kinney University of Wyoming G. A. Rebka, Jr., Spokesman D. Roberts Colorado College C. A. Bordner Tel Aviv University S. A. Wood

We propose to measure the doubly differential cross section for the three inclusive reactions n+ and n~ inelastic scattering and K~ double charge exchange on 3He at a series of identical incident energies and pion angles: 25, 50, 80, 105, and 130° at each of three incident energies, 120, 180, and 240 MeV. At each angle the pion energy spectrum will be measured from its high-energy threshold down to 10 MeV. Most of these measurements should have 5% accuracy limited by systematic uncertainties and normalization; some will have an accuracy limited to 10 or 15% by the counting statistics. Measurement, calibrations, and tests will be completed in 640 h and will use the same spectrometer-detector system that was successful in measuring 'Hefa*,^), "0(1^,1:*), and '"Ca^^n*) cross sections. The facilities required at LAMPF are (1) a 500-uA, 800-MeV primary proton beam on the standard A-2 target; (2) standard performance of the P3 beam for pions; (3) the same space in P3-East or P3-West as used in Exps. 99, 309, 337, 750, and 783; (4) the P3 beam delivered to its dump without obstruction; (5) a 500-kW (2000 A at 250 V) magnet supply and 40 gal/min at AP = 300 psi of 65°F deionized cooling water; (6) an active shunt for the top magnet of the spectrometer; (7) a standard PDP-11 computer and data-acquisition system; and (8) a liquid JHe target system for the existing scattering chamber.

166 LAMPF USERS GROUP PROCEEDINGS November 19S3 Los Alamos National Laboratory Exp. 857

INELASTIC PION SCATTERING FROM 16O

ATrn=50MeV University of Texas, Austin L. C. Bland and C. F. Moore, Spokesmen University of Minnesota S. J. Seestrom-Morris Los Alamos National Laboratory J. J. Kelly, C. L. Morris

l6 ± +l We propose to study the feasibility of measuring O(n ,n ) at Tn = 50 MeV with the new spectrometer to come on line at LEP in 1984. These measurements should help identify the important terms in the pion-nucleus optical potential for low-energy scattering. The importance of coupled-channels effects in low-energy inelastic scattering also will be investigated by these data.

Exp. 858

ADDITIONAL MEASUREMENTS OF 16O(n+,jr)l6Ne(g.s.)

University of Pennsylvania H. T. Fortune and R. Gilman, Spokesmen P. Kutt University of Texas, Austin L. C. Bland, M. K. Brown, C. F. Moore, P. A. Seidl New Mexico State University G. R. Burleson, W. B. Cottingame Los Alamos National Laboratory C. L. Morris

Recently obtained angular distributions for the nonanalog double-charge-excnange (DCX) reaction "T0(JT+,7Ol6Ne(g.s.) at energies of 120 and 200 MeV may indicate that the nonanalog amplitude is not diffractive. We propose to take additional points at each energy to further investigate the variation in shape of the angular distributions with energy.

November 1983 LAMPF USERS GROUP PROCEEDINGS 167 Los Alamos National Laboratory Exp. 859

STUDY OF THE A DEPENDENCE OF INCLUSIVE PION DOUBLE CHARGE EXCHANGE IN NUCLEI Los A lamos National Laboratory P. A. M. Gram, Spokesman D. W. MacArthur Massachusetts Institute of Technology J. L. Matthews, Spokesman E. R. Kinney University of Wyoming G.A.Rebka, Jr., Spokesman D. Roberts Colorado College C. A. Bordner Tel Aviv University S. A. Wood

We propose to measure the doubly differential cross section for the inclusive double-charge-exchange processes (it+,7t~) and (n~,7t+) for a series of nuclei at three incident energies in the vicinity of possible A- resonance production (120, 180, and 240 MeV). For each incident pion charge and energy, we expect to measure at three angles (25, 80, and 130°), and for each angle at 9 or 10 energies judiciously spaced over the allowed spectrum of the outgoing pion. Most of these measurements should have 5% accuracy limited by systematic uncertainties and normalization; some will have an accuracy limited to 10% by the counting statistics. Measurement, calibrations, and tests will be completed in 520 h and will use the same spectrometer detector system that was successful in measuring 4He()t±,7t:F), 16O()t±,jt:f), and ^C^Jt*,)!*) cross sections. The facilities required at LAMPF are (1) a 500-uA, 800-MeV primary proton beam on the standard A-2 target; (2) standard performance of the P3 beam for pions; (3) the same space in P3-East or P3-West as used in Exps. 99, 309, 337, 750, and 783; (4) the P3 beam delivered to its dump without obstruction; (5) a 500-kW (2000 A at 250 V) magnet supply and 40 gal/min at AP = 300 psi of 65°F deionized cooling water; (6) an active shunt for the top magnet of the spectrometer; and (7) a standard PDP-11 computer and data-acquistion system.

168 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Exp. 860

INELASTIC n* SCATTERING TO EXCITED 0+ STATES AT ENERGIES BETWEEN 30 AND 80 MeV

University of South Carolina B. M. Freedom and C. S. fVhisnant, Spokesmen G. Adams, G. Blanpied, C. S. Mishra Virginia Polytechnic Institute and State University M. Blecher, B. Fick, K. Gotow, D. Wright Oak Ridge National Laboratory F. E. Bertrand, E. E. Gross, F. Obenshain Los Alamos National Laboratory R. L. Burman, M. Hynes, J. J. Kelly, C. L. Morris, E. Piasetzky University of Maryland N. Chant, B. G. Ritchie, P. Roos, H. Breuer No summary available.

Exp. 861

MEASUREMENTS OF THE SPIN-CORRELATION PARAMETER FOR np ELASTIC SCATTERING AT 800 MeV

Texas A.&MUniversity L. C. Northciiffe, Spokesman T. S. Bhatia, G. Glass, J. C. Hiebert, R. A. Kenefick, S. Nath Los Alamos National Laboratory D. Fitzgerald, J. J. Jarmer New Mexico State University G. Burleson University of Montana R. H. Jeppesen Washington State University G. E. Tripard

A measurement of the spin-correlation parameter <4NN(0*) for np elastic scattering at 800 MeV is proposed. A vertically polarized neutron beam {p ~ 0.5) obtained by precession of the polarized neutrons given by longitudinal polarization transfer from the LAMPF polarized proton beam bombarding a liquid- deuterium target would be scattered from a vertically polarized hydrogen target. The recoil protons would be detected in a multiwire-proportional-chamber (MWPC) magnetic spectrometer whereas the conjugate neutrons would be detected in a neutron bar counter (NBC) scintillator hodoscope having moderate position resolution. The background coming from quasi-free np scattering in nonhydrogenous target components would be distinguished by a test of the coplanarity of the incident beam and the scattered nucleons. The angjlar range to be covered would be 80° < 0* < 165°.

November 19B3 LAMPF USERS GROUP PROCEEDINGS 169 Los Alamos National Laboratory Exp. 862 STUDY OF THE Ml TRANSITION IN 88Sr BY THE INELASTIC SCATTERING OF Jt+ AND n~ Uttiversity of Minnesota S. K. Nanda and D. K. Dehnhard, Spokesmen C. L. Blilie, M. Garakani University of Texas, Austin L. C. Bland Los Alamos National Laboratory R. L. Boudrie, C. L. Morris, S. J. Seestrom-Morris Rutgers University C. Glashausser Tokyo University, Japan K. Maeda Tokyo Institute of Technology, Japan H. Ohnuma

We propose to measure the ratio of the n+ to n~ differential cross sections for the pure proton A/1 transition in ""Sr at 3.48 MeV of excitation energy with Tn+ 116 MeV at 19° of scattering angle. Our previous measurements for the 48Ca Ml transition to the 10.23-MeV state strongly indicate proton admixture in the transition density that is in disagreement with the pure neutron Ml transition usually assumed for 48Ca. Further data on a supposedly pure proton Ml transition, such as 88Sr, will greatly enhance our understanding of the proton-neutron composition of the Ml transition density.

Exp. 863 STUDY OF GIANT RESONANCES IN THE PALLADIUM ISOTOPES VIA PION SCATTERING Northwestern University A. Saha andK. K. Seth, Spokesmen D. Barlow, B. Harris, R. Seth

We propose to study the giant resonance region (10 to 25 MeV) in the palladium isotopes via n+ and jt~ inelastic scattering. Recent pion-scattering experiments in "8Sn indicate a large isovector strength in the region of the isoscalar giant quadrupole resonance at 13.2-MeV excitation energy, v»hich is not explained by any simple conventional model. We propose to study the characteristics of this giant resonance across a series of palladium isotopes with greater statistical accuracy and also to study the isovector properties of the other giant resonances present in the region.

170 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Exp. 864 STUDY OF DEEPLY BOUND HOLE STATES IN THE TIN ISOTOPES VIA THE {p,d) REACTION Northwestern University A. Saha and K. K. Seth, Spokesmen D. Barlow, B. Harris

Single neutron pickup reactions,like {p,d), have been used in recent years to study the deeply bound hole states in nuclei. Most previous studies have been done at incident energies of 90 MeV or less. It would be of great interest to see what characteristics these states exhibit at higher incident energies where momentum matching would preferentially excite high-spin states. In this experiment, we therefore propose to do the (p,d) reaction at 400 MeV on the tin isotopes. Excitation to the low-lying "alence states also will be investigated. These results are of importance for this study because they give a measure for the reliability of any reaction mechanism to describe the data.

Exp. 865 SPIN-ROTATION MEASUREMENT ON "He AT 320, 500, AND 800 MeV University of California, Los Angeles B. Aas, M. Bleszynski, and G. Igo, Spokesmen D. Adams, A. Azizi, E. Bleszynski, D. Lopiano, C. Newsome, G. Pauletta, F. Sperisen, A. Wang, G. S. Weston, C. A. Whitten University of Minnesota M. Gazzaly La

We propose to measure the spin-rotation parameters on 4He at HRS at 320, 500, and 800 MeV out to -/ = 0.45 (GeV/c)2, that is, past the first maximum in the differential cross section. Since 4He is a spin-0 nucleus, this completes the measurements of differential cross section (da/dQ) and analyzing power (Ay) at 350, 500, and 800 MeV partly done by other groups and at other facilities. This measurement, together with similar measurements on other light nuclei, will serve as a test of multiple-scattering theories.

Exp. 866 NEUTRINO SOURCE CALIBRATION University of California, Irvine R. Hausammann, Spokesman V. Bharadwaj, H. H. Chen Los Alamos National Laboratory J. Donahue, Spokesman R. L. Burman, E. Piasetzky. V. Sandberg Ohio State University E. Smith

No summary available.

November 1983 LAMPF USERS GROUP PROCEEDINGS 171 Los Alamos National Laboratory Exp. 867

MEASUREMENT OF ISOVECTOR QUADRUPOLE TRANSITION DENSITIES IN THE PALLADIUM ISOTOPES

Northwestern University A. Saha and K. K. Seth, Spokesmen D. Barlow, B. Harris

We propose to measure angular distributions for the low-lying states in the palladium isotopes via medium-energy proton inelastic scattering. Using electron-scattering results on the same isotopes, one can extract separate neutron and proton transition densities to these states. Recent microscopic IB A-2 model calculations can predict separate neutron and proton transitic , densities of the low-lying 2+ states in the palladium isotopes. The proton inelastic scattering data therefore will provide the necessary tests of this or any other model that is capable of predicting isovector properties of these states.

Exp. 868

AN EXPERIMENTAL TEST OF THE A-HOLE MODEL OF NONANALOG DOUBLE CHARGE EXCHANGE

Northwestern University K. K. Seth, Spokesman Los Alamos National Laboratory M. Kaletka

From measurements made on light even-even self-conjugate nuclei, it has been inferred that the AT= 2 nonanalog double-charge-exchange (DCX) transitions have o(5°) proportional to A~>n. This observation has been used to suggest a delta-hole model for nonanalog DCX. Since the A'4'3 law is based on observations on a very special class of nuclei, it is argued that many different explanations are possible. It is suggested that measurements on heavy nuclei will readily tell if the A ~i/3 behavior is a real general feature, and if the A-hole model based on it has any justification. It is proposed to measure o(5°) for ground-state AT= 2 DCX transitions on 88Sr, U0Ce, and 208Pb at 180 MeV.

172 LAMPF USERS GROUP PROCEEDINGS November 1983 Los Alamos National Laboratory Exp. 869 HIGHER PRECISION MEASUREMENT OF THE LAMB SHIFT IN MUONIUivf Yale University V. W. Hughes and A. Badertscher, Spokesmen S. Dhawan, D. C. Lu, M. Ritter, K. Woodle Heidelberg University M. W. Gladisch, Spokesman H. Orth, G. zu Putlitz College of William & Mory M. Eckhause, J. Kane University of Mississippi J. Reidy Los Alamos National Laboratory F. G. Mariam

Following our results of LAMPF Exp. 724, we propose to make a measurement of the Lamb-shift 2 2 7 interval 2 S1/2 - 2 Pl/2 in muonium to 0.1% precision and of the hfs interval in the 2 Pin state to 1% precision. The technique will be an extension and improvement of our LAMPF 724 experiment.

November 1983 LAMPF USERS GROUP PROCEEDINGS 173 Los Alamos National Laboratory Exp. 870

SEARCH FOR NEW MAGIC NUMBERS: DIRECT MASS MEASUREMENTS OF THE NEUTRON-RICH ISOTOPES WITH Z = 4-9

Los Alamos National Laboratory J. M. Wouters, Spokesman G. W. Butler, D. J. Vieira Clark University D. S. Brenner Brookhaven National Laboratory L. P. Remsberg Utah State University S. H. Rokni, K. Vaziri Iowa State University and Ames Laboratory F. S. Wohn University ofGiessen, W. Germany H. Wollnik

The overall goal of the time-of-flight isochronous (TOFI) spectrometer project is to perform, in a systematic fashion, direct mass measurements of light nuclei far from stability and thus identify general, as well as isolated, trends in nuclear structure. In this report we propose to measure in a systematic fashion the masses of the neutron-rich isotopes with Z = 4 to 9 using the TOFI spectrometer. Obtaining the masses of these nuclei will aid in the general understanding of this region of deformed neutron-rich nuclei as represented by the heavy sodium isotopes beginning with 31Na. Of special interest to nuclear structure studies are the predictions by various theoretical models that several new "deformed" neutron magic numbers at N= 10, 14, and/or 16 should exist, since the large N to Z asymmetry of these nuclei make them susceptible to deformation. Discovery of new neutron magic numbers would permit the study of the phenomenon of mutual support of "magicities" far from the valley of p stability in the light-Z region. Mutual support of magicities is the phrase used to identify the strong correlation between proton and neutron binding energies that is especially noticeable in nuclei near double-shell closures. Finally, this experiment will more clearly define the location of the neutron drip line as well as test the many models that predict the masses for this region. Specifically, the masses of I4Be, 17

174 LAMPF USERS GROUP PROCEEDINGS November 7983 Los Alamos National Laboratory Exp. 871

COINCIDENT NUCLEAR y-RAY AND PIONIC X-RAY STUDY OF n ABSORPTION AT REST ON 12C George Mason University B.J.Lieb, Spokesman •. College of William and Mary H. O. Funsten, Spokesman C. F. Perdrisat Florida State University H. S. Plendl, J. MacKenzie Virginia State University C. E. Stronach Utah State University V. G. Lind, R. E. McAdams, O. H. Otteson

We propose to measure nuclear y rays from JI~ absorption at rest on I2C in coincidence with (2P-XS) pionic x rays. The simple decay scheme of 10B should allow for a determination of the yield of residual

states following n~ absorption when in = 0 and when £„= 1. We hope to test selection rules for it" absorption and understand the mechanism that inhibits production of Jn, T=0+, I states in such reactions.

Exp. 872

DIRECT ATOMIC MASS MEASUREMENTS OF NEUTRON-RICH ISOTOPES IN THE REGION Z = 13-17 USING THE T1ME-OF-FLIGHT ISOCHRONOUS SPECTROMETER Clark University D. S. Brenner, Spokesman Los Alamos National Laboratory G. W. Butler, D. J. Vieira, J. M. Wouters Brookhaven National • Moratory L. P. Remsberg Iowa State University and Ames Laboratory F. K. Wohn University ofGiessen, W. Germany H. Wollnik

We propose to use the time-of-flight isochronous (TOFI) spectrometer to measure the atomic masses of neutron-rich isotopes in the region (Z = 13-17). These isotopes will be produced as recoil products from fragmentation of 238U following bombardment with 800-MeV protons. Optimization of the spectrometer performance and mass measurements of neutron-rich neon, sodium, and magnesium isotopes are to be performed in a previous experiment (No. 7'2). In the experiment proposed here, we shall extend mass measurements into the adjacent higher Z region where we plan to measure the masses of the following previously unmeasured nuclides: """Al, """Si, 3741P, 3M1""S, and «-44-45Cl. In addition, we will determine the masses of nine other isotopes in this region with improved precision and accuracy. Three new isotopes are expected to be discovered, 38A1,40Si, and 46C1, but with too few data to permit a determination of mass. These measurements will provide data for evaluation of effects on the mass surface caused by microscopic structures such as shell closures at N = 20 and N = 28, and subshell gaps

November 1983 LAMPF USERS GROUP PROCEEDINGS 175 Los Alamos National Laboratory at N = 14 and Z = 14. In particular, the development of mass systematics in the neutron-rich region beyond 34Si will provide valuable information for evaluation of the mutual support of "magicities" expected to arise from the Z = 14 submagic and N = 20 magic configurations.

Exp. 873 PIONIC X-RAY STUDY OF THE CARBON ISOTOPES Los Alamos National Laboratory E. B. Shera, Spokesman M. V. Hoehn, W. Reuter University of Wyoming A.R. Kunselman, Spokesman Purdue University Y. Tanaka Princeton University J. D. Zumbro

It is proposed to measure the pionic 2p-\s transitions in 12'14C to determine the strong-interaction energy shifts and level widths of the pionic is states of these nuclei. The experiment is important in defining the pion-nuclear potential and represents a unique opportunity to obtain T= 1 data in very light nuclei. The data will be complementary to a growing body of elastic pion-scattering data.

Exp. 874 ELASTIC SCATTERING OF n+ FROM DEUTERIUM 3 IN THE REGION OF THE F3 DIBARYON RESONANCE University of Minnesota C. L. Blilie and D. Dehnhard, Spokesmen M. Garakani, S. J. Seestrom-Morris, S. K. Nanda University of Texas L. C. Bland, C. F. Moore Los Alamos National Laboratory R. L. Boudrie, C. L. Morris New Mexico State University G. R. Burleson, W. B. Cottingame Tohoku University K. Maeda

We propose to take precise n* elastic-scattering data from deuterium between Tn= 150 and 300 MeV, in 15-MeV steps. A detailed angular distribution over the range 70-180° will be measured at each energy. Combining these large-angle data with existing small-angle data, we will then carry out a 3 phase-shift analysis to search for possible effects of the F3 dibaryon resonance on n-deuterium scattering.

LAMPF USERS GROUP PROCEEDINGS U.S. GOVERNMENT PRINTING OFFICE: 19W 776026 November 1983 Los Alamos National Laboratory