The Newsletter ofthe Fermi National Accelerator Laboratory

The search for the top quark THE TOP QUARK MAY HOLD has been underway ever since the bottom quark was THE KEY TO EXCITING discovered at Fermilab in NEW PHYSICS 1977. This search has not been an easy quest. For nearly 20 years it has domi- nated the efforts of thou- sands of people worldwide and has turned out to be one of the greatest chal- lenges faced by experiment- ers in high-energy physics.

WHAT'S SO SPECIAL ABOUT THE TOP QUARK?

Large international experiments at CERN (Geneva, Switzerland), DESY (Hamburg, Germany), KEK (T sukuba, Japan), SLAC (Stanford, California) THE FERMILAB TEVATRON IS THE ONLY ACCELERATOR and FERMILAB have all searched for ABLE TO WORK AT THE ENERGY LEVELS REQUIRED TO the top quark. Each experiment searched PRODUCE TOP QUARKS. ONE OF THE GOALS OF for many years and involved a large EXPERIMENTERS AT CDF AND D0 IS TO FIND THE TOP number of universities and laboratories. QUARK AND MEASURE ITS MASS.

Physicists have made predictions about Fermi News the mass of the top quark based on mathematical models and the experi- Friday, April 1, 1994 Volume 17, Number 6 mental evidence gained from past Peoples Testifies for HEP ...... page three searches. A little over a decade ago, many physicists believed that the top Deer Population on Rise ...... page five quark would be observed in experi- Main Injector Enclosure Contract Awarded ...... page five ments then being conducted at DESY. At that time the mass of the top quark People and Events ...... pages six through seven 2 was predicted to be about 15 GeV/c • continued to page two TOP QUARK continued from page one

Since the search began, experimental evidence has led to a steady rise in the 2 mass limit of the top quark. Recent PETRA at DESY 1984- 15-22 GeV/c results from the CDF and D0 experi- PEP at SLAC 1985 ments show that the top quark mass 2 must be at least 130 GeV/c • 2 (See Table I) Tristan at KEK 1988 26 GeV/c

"Scientists now know that the top quark SLC at SLAC 1989 41 GeV/c2 is at least that heavy because if the top 2 quark were lighter than 130 Gev/c , 2 we would have already discovered it," LEP at CERN 1990 45 GeV/c says G.P. Yeh, CDF.

HOW ARE TOP QUARKS PRODUCED? Tevatron at 1988 49 GeV/c2 Today, the Fermilab Tevatron is the PERMILAB and only accelerator able to achieve the SppS at CERN energies necessary to confirm the exist- ence of the top quark. If the mass of the top quark is less than 180 2 2 SppS (UA-1) 1990 60 Gev/c GeV/c , it should be discovered at Fermilab in the near future. One of the at CERN goals of CD F and D0is to find the top quark and determine its mass. SppS (UA-2) 1990 69 GeV/c 2 at CERN Tops are produced in pairs when a light quark in the proton and a light Tevatron (CDP) 1990 72-77 GeV/c 2 antiquark in the antiproton annihilate to form a top-antitop pair. Since the at PERMILAB Standard Model predicts that the top should almost always decay into a W Tevatron (CDP) 1992 91 GeV/c 2 particle and a bottom quark, we expect a top-antitop event to produce a w+w- at PERMILAB pair and bottom and antibottom quarks. This assumption must be T evatron (D0) 1994 131 GeV/c 2 tested. The top is so massive, it might decay in ways not included in the at PERMILAB Standard Model. "Nature is the ulti- mate arbiter; she tells us if we are right Table I: There has been a steady progression in the mass limit ofthe top quark or wrong," says Stephen Parke, RD/ ftom 15 GeV/c2 to the most recent published limit of131 GeV7c2. The Theory Department. Standard Model requires that the top mass be less than about 200-250 Ge V/c2. Ifthis mass range can be completely explored then either the top quark will be discovered or the Standard Model will be shown to be incorrect. If current predictions are correct, the T evatron and its upgrade, the Main continued to page four

2 FermiNews April 1, 1994 PEOPLES TESTIFIES FOR HEP "The United States has a BEFORE SCIENCE superb capability for SUBCOMMITTEE forefront research in elementary-particle phys-

OnJanuary26, 1994, the Science Sub- cording to known physical laws. Yet ics for the next decade- committee of the House Science, Space despite its success, this picture also but it can be realized only and Technology Committee held a raises profound questions that only new hearing on the future of high-energy experiments can answer. These ques- if there is sufficient fund- physics research in the United States. tions present great opportunities for ing to make efficient use Director JOHN PEOPLES testified discovery. Throughout most ofthe long before the subcommittee, along with period of its development, the U.S. led of our existing world-class panelists Roberto Peccei, past chair- the world in making contributions to facilities."-john Peoples man of the American Physical Society's the understanding of matter and en- Division of Particles and Fields, and ergy. Today, the U.S. is still one of the Frank S. Merritt of the Enrico Fermi leaders in this global field of research. Institute of the Universtiy of Chicago. In spite of the termination of the SSC, offers the best prospect for U.S. experi- Previously, Martha Krebs, DOE's di- the U.S. can make many important mentalists to work at the energy fron- rector of Energy Research; John Gib- contributions to elementary-particle tier in the next decade," said John. bons, director of the Office of Science physics for the remainder of the de- Krebs agreed and spoke of a "vision of and Technology Policy, and Robert cade. But, afrer that, we will not remain the future" that could include the LHC. Eisenstern ofthe National Science Foun- among the leaders in the ensuing de- dation testified as part of the first panel. cades unless we rebuild our capability John said that U.S. participation in the to construct and operate world-class LHC will probably require a contribu- The panelists emphasized the impor- facilities." tion of roughly $500 million to CERN tance of maintaining sufficient fund- for the construction ofLHC and of the ing for the base high-energy physics John added that the funding for the two detectors. "This would require a program. "The most logical and cur- base program is no longer sufficient to 10 percent increase in high-energy phys- rent steps forthe U.S. program in high- "allow achievement of the great poten- ics funding, in addition to funding for energy physics are to complete in timely tial for discovery in the U.S. and it the base program over the 10-year pe- fashion the Fermilab Main Injector certainly does not allow for new projects. riod between 1995 and 2005-a very and the Stanford B-Factory (and) to Nevertheless, some superb opportuni- small number compared to the funds provide full operational funding for ties exist and they can be realized with previously allocated to the SSC," John these facilities once they are completed a modest increase in funding." commented. in order to achieve the most and best physics research," said Gibbons. There was also general agreement by The future of the program is now being the panelists that the U.S. high-energy assessed by a subpanel of DO E's High John Peoples said, "The United States physics program would benefit from Energy Physics Advisory Panel chaired has a superb capability for forefront the United States participation with by Sidney Orel!. They will issue a re- research in elementary-particle physics CERN in the construction of the Large port in May. for the next decade-but it can be Hadron Collider (LHC). "The SSC realized only if there is sufficient fund- has been terminated and we know that The American Physical Society's Divi- ing to make efficient use ofour existing research at the energy frontier will not sion of Particles and Fields has also world-class facilities. Research in par- proceed by that route in the U.S. for established a series of working groups. ticle physics over the past 60 years has the foreseeable future. The LHC pro- They will issue a report in about a year. produced a remarkably successful theo- posed by CERN is scheduled for retical picture describing matter and completion early in the next century. Full text of John's testimony can be energy as built of certain constituents, While it has only a third of the energy obtained from the Publications Office, interacting through specific forces ac- that had been planned for the SSC, it WH15SW, by requesting TM-1876.

April 1, 1994 FermiNews 3 particle. Various models and theories, TOP QUARK including the Standard Model, seek to continued ftom page two It is remarkable that the explain why quarks have mass. Pre- cisely measuring the mass of the top top quark, if it exists, is so Injector, should produce a large sample quark may give us real insight into of top quarks. From these studies physi- massive. The minimum what causes mass. That is why studying cists will be able to test the validity of top quark mass of 130 the top quark is so exciting. "We don't the Standard Model. 'The Standard know if the top is the Yeti or just the Model appears to be true. Right now GeV/c2 means that the top footprints of the Yeti," says Chris Hill, we are just confirming that people who quark is heavier than RD/Theory Department. "The Stan- have come before us are right. But, dard Model is not complete. We need because the top quark is so massive, nuclei of 53 of the I 07 something to explain the quark masses," there is the possibility we are on the elements in the Periodic says Stephen. Understanding the ori- verge of discovering completely new gin of mass would be "an achievement physics," says Stephen. Table, including tin and on a par with the greatest scientific silver. In contrast, the strides in history like Newton's estab- lishing the universal law of gravitation bottom quark, which is the WHY IS THE TOP QUARK SO or Einstein's connection of energy to HEAVY? heaviest among the first mass and the speed of light," says Chris. five quarks, has a mass of Why the top quark is so heavy remains The CDF and D0 collaborations have 2 a mystery and the answer to that ques- only 5 GeV/c • The proton set their sights on the discovery of the tion may lead to a whole new era of 2 top quark. After they find it, their focus has a mass of 0.9 GeV/c • physics. "Partly because it must be so will shift to the determination of its massive, the top quark may shed light - G.P. Yeh. mass and the observation of its major on the origin of mass, one of the most decay modes. urgent questions particle physicists can Continued to page five address," says John Huth, CDF.

The top quark is by far the heaviest of all the funda- mental particles. It is currently pre- dicted to be about forty times heavier than the second heaviest quark, the bottom quark. (See Table II)

Although we do not know why the top quark is so heavy, some physi- cists believe that the mechanism that causes mass is somehow more closely connected to the top quark QUARKS than to any other Table II

4 FermiNews April 1, 1994 FERMILAB'S DEER POPULATION ON RISE

Fermilab's deer population is continu- Rod noted the distribution of deer has ing to grow, according to a recent aerial also changed since last year. Since the count of the site by ROD WALTON Main Injector project began, the deer of ES&H. Three hundred and forty population appears to have shifted into deer were counted this year during the the center of the ring. There were 159 March 1 helicopter survey. This is an deer inside the ring the day of the increase from last year's count of 305 count-a density of 140 deer per square deer. mile. "The optimum density is some- where in the neighborhood of 10 to "This is an 11. 5% increase in one year," 15." said Rod. "If this rate of increase con- tinues unchecked, the deer population Rod indicated he was somewhat sur- could double in less than six years. And prised by the increased deer popula- that is a lot more deer than we can tion. "I wouldn't have been surprised if 19 in 1993. handle." I saw less deer (during the count) than last year because I haven't seen many Rod said the Laboratory does not have Rod said he was concerned by the small deer while driving on site." But, as Rod enough statistics on the deer popula- size of some of the deer during the explained, one reason for the fewer tion growth to know what can be done count. "This may be due to decreased sightings could be the good growing to regulate their population right now. growth because of nutritional stress, season last year. There was ample food or, more likely, it may indicate a large for the deer and there was little need for "We won't do anything until we have a number of yearlings, which will likely them to move around the site to find it. better idea ofwhat is going on.We will begin reproduction next year." Either Although deer may have traveled less be looking for the natural environment situation is not good, for the deer and throughout the site, deer accidents with to curb the population. We'll wait and for the Lab, Rod added. vehicles increased from nine in 1992 to see. "

TOP QUARK MAIN INJECTOR ENCLOSURE continued from page four CONTRACTAWARDED According to John Huth, "We do not search for the sixth quark merely to fill in a blank. Without the top quark, the The contract for the construction of the The enclosure project entails carving Standard Model collapses. The Main Injector Enclosure was recently out a 10,600-foot oval ring to a level Fermilab T evatron can settle the issue awarded to a local construction com- between 20 and 30 feet below grade. by actually producing and measuring pany. Wil-Freds of Naperville was When complete, the interior dimen- the mass of the top quark. The situa- awarded the contract March 18 for the sions of the enclosure, which will house tion is tantalizing because we may largest single piece ofcivil construction at the accelerator itself, will be typically actually be entering a new era in which the Laboratory since its initial building. eight feet high by 10 feet wide. the Standard Model begins to self- destruct and our understanding of The Enclosure work will be done in Director JOHN PEOPLES said, "I am basic forces will actually be increas- two phases over 22 months and will delighted with the continued support ingly challenged." employ about 350 workers from local of DOE for this project. I believe this communities. This project is the sev- contract award is an important mile- This is a second in a series of enth bid package awarded since work stone as we upgrade Fermilab's accel- FermiNews articles written by Labo- on the Main Injector began in July erators for exciting physics research in ratory staff on the search for the top 1992. the near future." quark.

April 1, 1994 FermiNews 5 People Events

ENGLER The Fermilab Arts Series presents the Winifred Haun & Dancers Choreographer's Showcase, highlight- RETIRES ing some of the best dance talent in the dance forms: tap and modern, to create area. This year's showcase brings back exciting and innovative performances. two familiar yet quite different compa- N O R B nies and presents a new force in the For reservations, call xARTS weekdays ENGLER, a dance community. Don't miss this from 9 a.m. until 4 p.m. long-time em- unique sampling ofgreat Chicago dance ployee in Tech- on Saturday, April 16 at 8 p.m. in nical Support, Ramsey Auditorium. Tickets are $10. TORNADO retired from the Lab March 31. A beloved mainstay in Chicago is Jo- SEMINAR Norb started working at Fermilab as a seph Holmes Chicago Dance Theater. contractor in January 1971. He be- Celebrating its 20th year, this modern COMING came a permanent employee in No- jazz company performs all original vember of that year. works, often using specially commis- sioned music. The Fermilab annual tornado seminar In his retirement, Norb said he plans to will be held Saturday, April 9, 1994 in "do nothing." "I look forward to hav- Winifred Haun & Dancers burst onto Ramsey Auditorium. Sessions will be ing more time to boat and motorcycle the Chicago dance scene in 1991 and held at 1 p.m. and 7 p.m. As in years and be 'Mr. Mom'-take my wife to has since captured the attention of both past, meteorologist Tom Skilling from work, do things at home .... It's going to audiences and critics, winning two Ruth WGN-TV will be the featured speaker. be nice." Page nominations for Choreographer of Among others scheduled to speak in- the Year. The company presents emo- clude Bill Hirt from the National Se- Norb said he first took the job at the tionally charged and compelling dance. vere Storms Forcast Center in Kansas Laboratory thinking it would be a tem- City, Missouri and Jim Allsopp from the porary position, but it turned out to be am/FM blends two distinctly American National Weather Service, Chicago. a permanent position-22 years worth. "It's been a good 22 years. I've learned a lot and many people helped me. This is the one place I've worked where the people I've worked with were col- leagues-that made it a nice place."

ARTS SERIES PRESENTS

The Choreographer's Showcase: Joseph Holmes Chicago Dance Theater, Winifred Haun & Dancers, am/FM

6 FermiNews April I, 1994 STOCKROOMS DO YOU ANT TO QUIT? TO CLOSE The Wellness Works Committee is to quit smoking (hopefully in early to organizing a support group for those mid-April). At this point you're prob- The Fermilab Stockrooms will be closed who are quitting smoking. The first ably thinking, "This is goofy, I'll just for annual inventory on the following meeting is Monday, April 4 at noon in quit on my own." But guess what? schedule: the Comitium. The group will meet Apparently group "quits" have a much twice weekly (Tuesdays and Thurs- greater success rate than other tech- Hall Stockroom: days), at noon, during April. On Thurs- niques. Other information and sup- Closed Friday, May 13 at 12 noon. Re- day, April 7, a clinical psychologist port we will present include nutrition open Monday, May 16 at 12:30 p.m. knowledgeable on cessation techniques, to help cravings, ex-smokers advice, Site 38 Stockroom: will speak to the group. At the first perhaps utilizing a buddy system and, Closed Monday, May 16 and Tuesday, meeting, we anticipate voting on 'The of course, the dreaded relapse. Don't May 17 all day, both days. Great Fermilab Smoke Out Date" - put it off, spring is the best time of year the day in which everyone will be ready to quit! -Audrey Hopper WELLNESS NO PAIN, NO GAIN

COMMITTEE Join the spring aerobics class Mondays cises. Men, women and beginners are and Wednesdays from 5:30 until 6:30 welcome. Class begins April 11. The SCHEDULE p.m. at the Recreation Facility. The cost is $2 per class. If interested contact class offers a combination of low im- Jean at x2548. You must be a current ANNOUNC:ED pact and step aerobics and toning exer- gym member to enroll in the class.

The Wellness Works Committee has announced its spring schedule ofevents. Mark your calendars for these "health- ful" events.

Wednesday, April 6, 1994: Infor- mational meeting on Weight Watch- ers, noon to 1 p.m., Curia II. Tuesday, April 12, 1994: Blood pressure checks, Wilson Hall Atrium, 11:30 a.m. to 1 p.m. Wednesday, May 18, 1994: Em- ployee Health & Fitness Day. (Watch Ferminews for further information.)

Director Emeritus Robert Wilson Honored Average number ofsesame seeds on a Former director Robert Wilson enjoys his birthday cake at the international symposium Big Mac: and tribute in honor ofhis 80th birthday held at the Laboratory March 4. The day- 178 long symposium featured talks and reflections by many of Wilson 'scolleagues and .friends. A video, created by Fermilab 'sVisual Media Services detailing Wilson 's Total value of the 96,000 refund professional life, was also presented. Alvin Tollestrup, john Peoples, Chris Quigg, checks returned to the I.RS. as un- Heidi Schellman, Leon Lederman and Lillian Hoddeson were among the many deliverable last year: presenters at the symposium who offered their reflections and outlined the contributions Wilson has made to Fermi/ab and to the world ofphysics. $50,000,000 (The cake was designed and made by Liz Stupak, ·a Fermi/ab cafeteria attendant.)

April 1, 1994 FermiNews 7 LIBRARY NEWS

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8 FermiNews April I, 1994 -(:{ U.S. GOVERNMENT PRINTING OFFICE: 1994-546-059/80017