A Joint Fermilab/SLAC Publication Dimensions of Particle Physics Issue

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dimensions volume 03 of particle physics symmetryA joint Fermilab/SLAC publication

issue 05

june/july 06 Cover Physicists at Fermilab ponder the physics of the proposed International Linear Collider, as outlined in the report Discovering the Quantum Universe.

Photos: Reidar Hahn, Fermilab

Ofﬁce of Science U.S. Department of Energy volume 03 | issue 05 | june/july 06

symmetryA joint Fermilab/SLAC publication

3 Commentary: John Beacom “In a global ﬁ eld, keeping up with all the literature is impossible. Personal contact is essential, and I always urge students and postdocs to go to meetings and talk to strangers.”

4 Signal to Background An industrial waterfall; education by placemats; a super-clean surface; horned owls; Garden Club for particle physicists; Nobel banners; US Congress meets Quantum Universe.

8 Voices: Milestones vs. History Celebrating a milestone is always enjoyable, but a complete and accurate historical record is invaluable for the past to inform the future.

10 A Report Like No Other Can the unique EPP2010 panel steer US particle physics away from a looming crisis? Physicists and policy makers are depending on it.

14 SNS: Neutrons for ‘molecular movies’ A new research facility at Oak Ridge National Laboratory has produced its ﬁ rst neutrons, presenting new opportunities for studying materials from semiconductors to human enzymes.

20 Battling the Clouds Electron clouds could reduce the brightness—and discovery potential—of the proposed International Linear Collider. Innovative solutions are on the way and might reduce the cost of the machine, too.

24 A (Magnus) Force on the Mound Professional baseball player Jeff Francis of the Colorado Rockies brings a strong arm and a physics background to the playing ﬁ eld: “I bet Einstein couldn’t throw a curveball.”

26 Deconstruction: Spallation Neutron Source Accelerator-based neutron sources such as the SNS can provide pulses of neutrons to probe superconductors, aluminum bridges, lighter and stronger plastic products, and pharmaceuticals.

28 Gallery: Ellis Paul Reading about astronomy, folk musician and songwriter Ellis Paul began to ask himself whether Galileo Galilei could embrace both science and faith. Paul wrote the song, “Did Galileo pray?”

30 Essay: Verlyn Klinkenborg “This country desperately needs to recommit itself to basic research…Do we continue to ask fundamental questions about the universe we live in, or do we not? To me, there is only one answer.” bc Logbook: First Vertex Detector The Mark II collaboration operated the ﬁ rst collider vertex detector in 1981. Today, these devices—now using silicon technology—are the centerpieces of high-energy collider experiments around the world. ibc 60 Seconds: Elementary Particle Physics What rules govern energy, matter, space, and time at the most elementary levels? How are phenomena at the smallest and largest scales connected? Particle physicists are going to ﬁ nd out. from the editor

Bold experiments can be convincing Physicists live to experiment: usually in a lab, but at times in different venues. The National Academies committee that recently looked into the future of US particle physics was a new kind of non-laboratory experiment for the physics community. Realizing that their field was facing a turning point—gradual decline versus bold steps toward an ambitious future—physicists effectively put their fate in the hands of those outside their profession. The EPP2010 committee, as it was known, included enough non-physicists to keep the physicists from automatically control- ling the decision-making. Thus, conclusions were not foreordained. Although the EPP2010 report makes no binding decisions and has no official influence, it is an important sign to policy makers from Congress’ independent science advisory body. The diverse group, whose members are accustomed to making high-level decisions about the futures of organiza- tions, recommended an admittedly risky path for US particle physics. But it emphasizes that all possible paths are risky: continuing the status quo only promises the field will wither over time. No set of recommendations can please everybody, especially those with strongly vested interests in particular projects. What is important now is how physicists respond to this report. At some point, physicists need to convince the wider community of the value in spending a lot of public money to pursue their plans and ambitions. Would physicists rather take the case directly to the public, where the processes of spin can easily dominate a debate? Or would they like to go directly to Congress, where political and time pressures might be deci- sive? The EPP2010 committee offered ample opportunity for rebuttal and discussion. Although by no means an easy group to convince, the EPP2010 committee proved to be more accepting than others might be. This risky approach paid off because of the careful attention and respect the physics community gave to the process. If particle physicists want to pursue their grandest ambitions, they will need to take more risks like this one; they will also need to play the next steps at least this carefully. A misstep could be the end of it all. For now, physicists should be very pleased that they can successfully convince important audiences that their plans are indeed worthwhile. David Harris, Editor-in-Chief

Symmetry Editor-in-Chief Publishers Print Design and Production PO Box 500 David Harris Neil Calder, SLAC Sandbox Studio MS 206 650 926 8580 Judy Jackson, FNAL Chicago, Illinois Batavia Illinois 60510 USA Executive Editor Contributing Editors Art Director Mike Perricone Roberta Antolini, LNGS Michael Branigan 630 840 3351 telephone Dominique Armand, IN2P3 630 840 8780 fax Managing Editor Peter Barratt, PPARC Designer www.symmetrymagazine.org Kurt Riesselmann Stefano Bianco, LNF Aaron Grant Tara Kennedy [email protected] Staff Writers Reid Edwards, LBNL Elizabeth Clements Petra Folkerts, DESY Web Design and Production (c) 2006 symmetry All rights Heather Rock Woods Catherine Foster, ANL Xeno Media reserved Siri Steiner Barbara Gallavotti, INFN Hinsdale, Illinois Kelen Tuttle James Gillies, CERN symmetry (ISSN 1931-8367) Silvia Giromini, LNF Web Architect is published 10 times per year Interns Jacky Hutchinson, RAL Kevin Munday by Fermi National Accelerator Jennifer Lauren Lee Youhei Morita, KEK symmetry | volume 03 issue 05 june/july 06 Laboratory and Stanford Chandra Shekhar Marcello Pavan, TRIUMF Web Design Linear Accelerator Center, Krista Zala Mona Rowe, BNL Karen Acklin funded by the US Department Yuri Ryabov, IHEP Protvino Alex Tarasiewicz of Energy Ofﬁce of Science. Yves Sacquin, CEA-Saclay Web Programmer Boris Starchenko, JINR Mike Acklin Maury Tigner, LEPP Jacques Visser, NIKHEF Photographic Services Linda Ware, JLab Fermilab Visual Media symmetry Tongzhou Xu, IHEP Beijing Services

2 commentary: john beacom worldwide well enough to talk comfortably with tostrangers. talk students andpostdocstogomeetings and urge always I and essential, is contact Personal dozen new papers daily on the arXiv.org server. several are there impossible: is literature the all with up keeping field, global a In are. you who know they if papers your read papers—they’ll won’t get toknowwhoyouarebyreadingyour A factoflife foraspiringphysicistsisthatothers Family Business Astrophysics Group.Will Kinney, nowafaculty Theoretical Fermilab the of students and docs it in another (well, usually). can gain membership in one family without losing and cousins. It’s not quite like mafia families: one position brings new mentors, and more siblings are extended and complicated, and each postdoc a family resemblance in style. Physics families same mentor, evenifseparatedintime,willbear yearstolearnbyexample. Studentsofthe take in isolation. Methods of thinking and judgment too, since no one can learn to do physics research and predecessors. peers their to applicants the compare they how and ever”?), “best the student every (is years to who’swriting,whattheywroteinprevious Letters havetobecarefully calibratedaccording others. than equal more are some good—but we hadn’tmet. At first,theletters soundequally applicants about mostly reference, of letters postdoc search and read more than a thousand At Fermilab, Iorganizedourannualastrophysics provide theopportunitytobejudgedonmerits. can connections these but meritocracy, a is families arefinallyincludingmorewomen.) “grandfather,” andsiblingsare.(Nowadays,these “father,” PhD our who know We all comed. wel is input Community spires/hepnames/). hepnames genealogy.math.ndsu.nodak.edu/). until Gaussorsomeotherheroicfigure(http:// advisor’s advisor, and so on through the begats genealogy basedontheirPhDadvisor, andtheir will beonthefinalexam. nections between thelivinganddead,it con of web changing and intricate, vast, a of of separation”looksimple.Physicistskeeptrack a culturalconstructionthatmakes“sixdegrees gaps inourknowledgeofotherpeople?With andsohowdowefillinthe is hardlyeveryone, out reintroduction, and that’s not unusual. But this I mustknowseveralhundredotherphysicists In May, we hadagatheringofformerpost But these family ties have a deeper meaning, Connections accelerate identification. Physics A partialphysicsfamilytreeisgivenin Mathematicians haveawell-documented (http://www.slac.stanford.edu/ spires

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3 given the freedom to develop their own research greatly appreciatedhowthey’dsimilarlybeen international institution it is today. dom and responsibility to build the group into the the young Rocky Kolb and Mike Turner the free andLeonDavid Schramm Lederman, whogave bythegodfathers group wasfoundedin1983 eccentric relatives. The ing heard about, and tell meeting people I’d only iar faces again, finally reunions: seeing famil family other like the group. It was much the current head of it with Scott Dodelson, reunion and organized the initiated Buffalo, SUNY at member fnal.gov/alumni/reunion.html http://www-astro-theory. at available is reunion Astrophysics Theoretical Fermilab the on Information cousins. physics of lot a has he that meaning uncles, and aunts many with Vogel, Steve Koonin, Baha Balantekin, and Adrian Melott, along Kolb, Mike Turner, Rocky Petr counts he mentors, primary his Among Ohio. Columbus, in University State Ohio The at Astronomy and Physics in member faculty a is (2000–2004), John Beacom,thefirstDavidN.SchrammFellow atFermilab John Beacom table. kids’ the at sit to have don’t you as long as there, being like nothing still there’s but connections, facilitate email and ideas andmaketheworkmorefun.The web new spark to interactions personal on depend seminar talks. tovisitandgive withinvitations collaborations new seeding and detail, in projects ongoing ing a lotofseriousbusiness.This includeddiscuss had 100), ‘inflation’ there in was the title?”—about many ofthe1000+paperswrittenbygroup the daywithatriviagame(questionslike“How ended we While similar. remarkably were group tives working on very different things, but our perspec are and met, never had us of Many level. est high the at perform to challenged being while A common reunion theme was that everyone A commonreunionthemewasthateveryone Even the most technical physics projects projects physics technical most the Even stories onresearch andwhatwelearnedinthe about our

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Photo courtesy of The Ohio State University

symmetry | volume 03 | issue 05 | june/july 06 signal to background

An industrial waterfall; education by placemats; producing a super-clean surface; horned owls at SLAC; garden club for particle physicists; Nobel banners back on display; US Congress meets Quantum Universe. Photo: Diana Rogers, SLAC Photo: Diana Rogers, SLAC

SLAC’s water cycle vacuum systems, klystrons, by powerful fans on the cooling Along the Loop Road at magnets, and other parts that tower roof. On cool mornings, Stanford Linear Accelerator drive the accelerators. Cooling columns of steam rise from the Center, the roar of falling water Tower 101 lowers the tempera- cooling towers. Some loose and a refreshing mist filled ture of the chillers that cool water evaporates into mist. the air after six solid weeks of computer components in the To replenish one cooling California rain. But the water Computer Building. tower, SLAC recycles half a mil- cascading down the inside of Water flows through pipes lion gallons of water a year. In Campus Cooling Tower 101, next to hot equipment, soaking winter, crews from Conventional and landing in a frothy pool, is up the heat. The pipes run to & Experimental Facilities pump hardly scenic. The corrugated nearby heat exchangers, trans- rainwater out of manholes with metal building sprouts pipes ferring the heat to water in a truck called “The Dominator.” of all sizes. The bottom section another set of pipes. The cool- After filtering the water, they top

of the front façade is open ing water ﬂows back to the off Cooling Tower 1701, also symmetry | volume 03 issue 05 june/july 06 except for mineral-encrusted cooling tower, like blood known as “The Big One,” near slats, allowing Loop Road returns to the lungs for more the downstream end of the lin- walkers to experience an oxygen. Spray nozzles release ear accelerator. Just like its wild industrial facsimile of the small droplets of the cooling water— brethren, the Big One’s waterfall falls that spring to life in the completely safe tap water—into carries real California rain. winter hills of California. the tower. As they fall through Heather Rock Woods The perennial cooling tower open air, the droplets release is one of six at SLAC that cools heat into the rush of air created

4 Images courtesy David Ehrenstein

From placemat to are trying to see them coming out to that extent. We decided prodigy from binary black holes. That’s to do a standard treatment Over a half-eaten burrito or a when two stars are constantly that has been done for some bowl of spaghetti, Sam orbiting one another and when years now, and we got the Ehrenstein ponders the unan- they die they become superno- best result that you can hope swered questions of funda- vae and then they become to get at this stage.” mental physics. Yet Sam is no black holes and they get closer Etching essentially cleans experimental physicist or post- and closer and finally smash the cavity, with the BCP treat- doc brooding over his data–not into one another and that ment removing a damaged layer yet, anyway. releases gravitational waves,” typically 100 micrometers thick. The seven-year-old son of he said. “You wouldn’t know Then, a high-pressure water Physical Review Focus Editor if gravitational waves were com- rinsing scrubs the surface clean. David Ehrenstein, Sam became ing without LIGO because Says Padamsee: “We showed interested in particle physics when they hit something they no field emission, which means by reading science-themed make it longer and shorter that our process is very clean.” placemats. “When he’s particu- but that’s undetectable except Purchased from ACCEL larly interested in a placemat, when you have special equip- Instruments in Germany, the he often will use two—one for ment like LIGO does. It’s fun to cavity underwent mechanical his plate, and one to read learn about and it can also be measuring and testing at unobstructed,” says David. “We useful and stuff.” Fermilab before being sent to have a lot of placemats.” Sam says he’ll probably be the SMTF collaboration part- Sam displayed his surpris- a pilot or an astronomer when ners Cornell and Jefferson ingly complex knowledge he grows up. Lab. The cavity will next be to Mrs. Robertson, his first grade Kelen Tuttle sent to JLab for electropolish- teacher, by writing a persuasive ing, and scientists eventually essay about his love of science. A top gradient for expect a gradient of 35 MV/m. On the back, he drew pictures of cleanliness Elizabeth Clements

the Stanford Linear Accelerator After undergoing a buffered Cornell University Photo: Hasan Padamsee, Center (SLAC), the Laser chemical polishing (BCP) Interferometer Gravitational- treatment at Cornell University, Wave Observatory (LIGO), the the first US-processed and Relativistic Heavy Ion Collider tested International Linear (RHIC), and the International Collider superconducting cavity Linear Collider (ILC). achieved a milestone acceler- In his first but probably not ating gradient of 26 MV/m last interview, Sam admitted (megavolts per meter)—sur- to mixing particle physics with passing the first gradient goal astrophysics. “I know LIGO (25 MV/m). The joint effort of isn’t a particle physics experi- the SMTF (Superconducting ment,” he said. “I guess I just Module Test Facility) collabora- got carried away.” tion was a first test for the US symmetry | volume 03 issue 05 june/july 06 Sam then went on to explain facilities for ILC. LIGO’s purpose: to detect “This is a good [first] achieve- gravitational waves. “They’re ment,” says Hasan Padamsee waves that usually come of Cornell University. “ILC cav- out of space. They come from ities have not been tested a bunch of things in space like in the US yet, and none of our supernovae but now scientists facilities have been checked

5 signal to background

original owners. Could this will ﬁnd more than three acres explain the bad blood between of gardens, most surrounded the two avian families? The by chain link fences or wire owls declined comment. Had mesh to “keep out the critters.” a raven been asked if it would Half a dozen garden sheds repeat the experience, one of various colors and degrees suspects it might have said, of weathering speckle the “Nevermore.” property, and there is even an Chandra Shekhar orchard. “It’s a friendly atmo- Particle physics sphere—international,” says Jim takes ﬂight The particle garden Wendt, a linac technician who Welcome to SLAC’s End Mesons. Bosons. Pions. Muons. has been gardening with the Station B, where work on the Asparagus. Yes, asparagus. club since 1970, two years before International Linear Collider Physicists have spare time, too, it moved to its present location

Photo: Diana Rogers, SLAC (ILC) will help shape the future and a few of them spend it and became an official club. of particle physics—although in Fermilab’s Garden Club, with Plots are 40 feet by 20 feet some inhabitants don’t seem to roots almost as old as the lab and cost $5 per year, with give a hoot. Until last month, itself. It was 1969 when farm funds going into maintenance End Station B was home to a manager Bob Hines began of shared gardening equip- family of horned owls, who allocating land to Fermilab users ment (such as lawnmowers and claimed a piece of real estate and employees for recreational rototillers) and other repairs. on the building’s ledge. gardening. Now the Garden “It’s nice during the summer- “Horned owls are common in Club boasts nearly 90 members, time to take a little break, the US,” says SLAC’s Michael growing everything from sweet get a little fresh air, get a little Scharfenstein. “But it is unusual corn to strawberries. “As long exercise, and then come to find them nesting on End as it’s legal, people grow just back to work,” Berman says. Station B.” about anything,” says Computing Whether they are studying The adult owls were seen in Division’s Eileen Berman, a the cosmos or treating it for their new residence early in club member for over 20 years. aphids, Fermilab’s Garden March. By the end of March, End Drive down the narrow Club members remind us that Station B had exerted its irre- gravel road through the trees physics and nature are peas sistible romantic influence, and at the northeast corner of in a pod. two adorable little baby owls the Fermilab Village, and you Jennifer Lauren Lee

had emerged. One of the babies Photo: Reidar Hahn, Fermilab ended up on the ground in early April. Rescued by Scharfenstein, the little ball of ﬂuff went to live at a rescue center. A few days later, the remaining owls vacated their nest without giving notice. Scharfenstein, an amateur ornithologist, witnessed the entire saga. “Owls are really shy,” he says. “It was a unique opportunity to see them like this.” Moving into a new neighbor- hood carries its risks. The owls did not get along with a family of ravens nesting on the adja-

cent building, End Station A. symmetry | volume 03 issue 05 june/july 06 “There was heavy sparring between the ravens and the owls,” says Scharfenstein. “It was pretty amazing to watch.” Nobody saw the owls build their nest. A family of ravens— perhaps the ones on End Station A—may have been the nest’s

6 G. Segre (1959); Luis Alvarez I believe that some day we will (1968); Donald A. Glaser (1960); understand the fundamental Charles H. Townes (1964), and forces of the universe.” current Berkeley Lab Director Greene’s talk, “Reaching for Steven Chu (1997). Chemistry Einstein’s Dream: The Quest Laureates: Wendell M. Stanley for the Deepest Laws of the and John H. Northrop (1946); Universe,” headlined an event William F. Giaque (1949); Glenn hosted by Congresswoman T. Seaborg and Edwin M. Judy Biggert and Congressman McMillan (1951); Melvin Calvin Rush Holt, members of the (1961), and Yuan T. Lee (1986). Science Committee in the US Economics Laureates: Gerard House of Representatives, Debreu (1983); John C. Harsany to launch the new High Energy (1994); Daniel L. McFadden Physics Advisory Panel publi- Nobel banners (2000), and George Akerlof cation Discovering the Quantum restored at (2001). Literature Laureate: Universe, a companion volume Berkeley Lab Czeslow Milosz (1980). to the Quantum Universe. Holt Street banners honoring nine Berkeley Lab News is one of two physicists in of Berkeley Lab’s Nobel Prize Congress; the other is Vernon Photo: Lyn Hunter, LBNL Photo: Lyn winners, originally installed US Congress meets Ehlers of Michigan. along Telegraph Avenue in 2003, Quantum Universe The director of the have been mounted on poles Have you ever tossed a ball Department of Energy’s Office on Cyclotron Road leading at a wall, playing a game of of Science, Raymond Orbach, to Berkeley Lab in honor of its one-man catch? As you tossed presented the report, which 75th anniversary. Uncovered that ball again and again and explains the discovery oppor- recently in storage, the deterio- again, have you ever thought tunities at the Large Hadron rating vinyl banners were about the chance that it could Collider and the proposed restored by the Lab’s Vic go right through the wall? International Linear Collider. Haskett of the paint shop. According to quantum mechan- “We are living in a world that The original installation ics, this is a real possibility. we still don’t really understand,” of 66 banners, sponsored “It’s a small probability, but it is Orbach said. “We don’t know by University of California, there,” said renowned physicist what happened at the beginning Berkeley, and Telegraph and author Brian Greene, who of the universe, and the ILC— Avenue merchants, celebrated addressed the Congressional referred to as Einstein’s tele- the Berkeley campus’ 18 Nobel Research and Development scope—will allow us to go back Laureates—13 for scientific Caucus Advisory Committee in in time and see what hap- achievement, four for econom- Washington, DC, on May 9. pened. This is a wonderful time ics, and one for literary success. After explaining the theory for us to be alive. There are When John Hickey, design of relativity, quantum mechan- so many questions of wonder director for UC Berkeley’s ics, and string theory all in the and beauty that exist, and we Public Affairs office, began span of an hour, Greene also have a shot of answering them.” work on the 2003 Telegraph summed up the process that Elizabeth Clements

Avenue project, he said he had physicists use to answer some Photo: Tissara Photography no idea what kind of an of the universe’s deepest mys- endeavor it would be. “We had teries. “We slam stuff together to work with some pretty old and see what happens,” he photos of Berkeley laureates,” said. Referring to the construc- he said. “Some were postage tion of the Large Hadron stamp-sized images that had Collider, Greene explained how been dug up from old depart- scientists can look at the ment files.” A few, fortunately, debris from the particle colli- were top quality, having been sions to learn if such ideas as shot by Berkeley portrait pho- dark matter, supersymmetry, tographer Paul Bishop; others and extra dimensions are real. had been shot more recently “This machine will test many symmetry | volume 03 issue 05 june/july 06 by his son, Paul Bishop, Jr. things,” he said. “If this experi- Quantum Universe Meets Hollywood: Actor Ernest O. Lawrence (1939) ment bears fruit, think about Alan Alda (left), a science supporter and was the first of Berkeley’s what that means. Every time host of the PBS series Scientific American Frontiers, chats with Brian Greene (center) Nobel Laureates in Physics. we put our minds to it, we have and Congresswoman Judy Biggert of Illinois Other Physics Laureates: been able to make progress. (right) at the R&D Caucus. Owen Chamberlain and Emilio We have never hit a wall, and

7 voices: milestones vs. history

Celebrating a milestone is always enjoyable, but a complete and accurate historical record is invaluable for the past to inform the future.

contrasts it to what he calls the “folk history” Looking Forward, phenomenon in particle physics: Looking Back: “...an increasingly unrealistic viewpoint of the pres- An Archivist’s ent generation of particle physicists regarding Perspective its past. The rich history...is increasingly distilled Last year the international physics community into a brief folk history. This was originally celebrated “The World Year of Physics.” A major designed for the non-specialist, but by now is reason for the timing of the celebration was used to teach new generations of students that 2005 marked the centennial of Albert as well. In the folk history, the Standard Model Einstein’s 1905 “Annus Mirabilis” (Miracle Year), was created as a relatively logical and straightfor- so called because Einstein’s three seminal ward process, while in reality it was a tortured papers—on the photoelectric effect, the size of one, with many false leads. It is hard for this gen- molecules and Brownian motion, and the theory eration of particle physicists to visualize the of relativity—were published in that historic year. rich environment of confusion, and the variety of What you might not know or remember is abandoned alternatives, from which the Standard that just two years ago, in 2004, the European Model ideology emerged. And it is difficult to particle physics laboratory, CERN, marked its now appreciate how hard it was to go from one 50th anniversary with a series of public events, step to the next...” a photo contest, an anniversary book of essays and photographs, and an “Open Day” at the lab. While distilled folk history has its place as a And that same year SLAC celebrated the 40th vehicle for communicating with non-specialists, anniversary of its founding with a series of special rich history is what specialists need, and what events, lectures, press releases, and publication archives strive to preserve. Why? Because the of a photo-history book. accuracy and comprehensiveness of rich history As an archivist, I am familiar with this sort of allow it to truly inform both the novice and the fuss about anniversaries and birthdays, and expert. I have even been known to initiate a bit of com- What Bjorken describes about the rich history memorative action myself. It is human nature of the Standard Model is true for the history to stop and look back when a milestone has of other scientific enterprises as well: rich history been achieved. Looking back is one way of shows that forward movement is often slow, taking stock, of reviewing the present in the and that breakthroughs are difficult. context of the past, and of coming to a better Rich history reminds those who study it that understanding—in the best of instances—of learning occurs even when mistakes are made both where one is going, and where one and sidetracks are followed, and that when you has been. (In addition, legitimate excuses for are on them, sidetracks can look very much like parties are never to be taken lightly!) main roads for a long time. The best milestone celebrations remind old Rich history is important because it is real, and hands, as well as teach new ones coming up, its reality can motivate and inspire present-day what it is that has become important about their novices and experts alike, because it reminds discipline’s or organization’s past, and what it them that the way forward has never been clear is about past achievements that still has value in or easy, and that those who succeed are those the present day. But a milestone celebration who bring a large measure of intelligence, energy, is just another party, however festive it may be, persistence, optimism, and, yes, luck, to bear on

unless the history it celebrates is meaningful, their research. symmetry | volume 03 issue 05 june/july 06 and meaningful history depends upon accuracy Accuracy and completeness in the historical in memory, accuracy and completeness in record, the foundation for rich history, does not records and documentation, and thoughtful his- mean that everything—every document, every torical analysis. presentation, every web page—has to be pre- In his recent book, In Conclusion: A Collection served. Before the advent of electronic media, Of Summary Talks In High Energy Physics the archival rule of thumb was that only 2-5 (2003), James D. Bjorken, Professor Emeritus percent of the paper documentation created by at SLAC calls such history “rich history,” and an organization or an individual is truly historically

8 Photos: Diana Rogers, SLAC Photos: Diana Rogers, SLAC valuable and warrants preservation. In the cur- works of leading scientists have resulted, and rent age of desktop, laptop, and handheld com- will continue to flow out, from the commemora- puting—and of the ubiquitous computer printer— tions of their milestone anniversaries. The books, the percentage of paper records deserving long- images, and archival deposits these celebrations term preservation has undoubtedly decreased, engender will continue to inform, instruct, and but the new era presents archives with a new inspire long after the celebrations themselves challenge: the need to develop best practices for have ended. preserving the small percentage of born-digital And in between celebrations, archives con- records that are historically significant, and that tinue their work of collecting and preserving are proving to be much less stable or permanent present-day records for future use, serving as than their paper-based counterparts. the bank vaults of rich history and paying divi- But archives and archivists have centuries of dends in the form of new conversations, new best practices to guide them in the digital era, reading, and new thinking about the past. and the methodologies that the profession has Archivists have a daily appreciation of the fact developed and used in the past to appraise that the past informs the future, and of the and select historically significant records are truth of what William Faulkner wrote, that “the now being adapted to 20th and 21st century past isn’t dead, it isn’t even past.” media. One critical difference is that the window Jean Deken of opportunity for the new digital media appears to be significantly smaller than that for paper- Jean Deken has been the archivist at the Stanford Linear Accelerator Center for 10 years. She is a Charter Member of the based records, which means that in this new era Academy of Certified Archivists, and is an investigator in the it becomes even more critical for archivists to US National Archives and Records Administration (NARA) have the active assistance and collaboration of Persistent Archives Testbed (PAT) research project to develop methods for archiving historically significant electronic records. records creators in the timely identification and She is currently collaborating with W.K.H. Panofsky on the selection for preservation of records of interest manuscript of a memoir of his life and career. She strongly to present and future historians. encourages you to check out the American Institute of Physics Center for the History of Physics web site Scientific Source Thoughtful historical analysis can only occur Materials: Saving Personal Papers and Archival Records when primary materials (documents, memoirs, in Physics and Allied Fields at http://www.aip.org/history/ images, interviews, etc.) are preserved and are source.htm for guidance on dealing with your records. available for research. This is one of the reasons In the interest of full disclosure, Jean would like to point out that why archivists kick their efforts into overdrive she is a veteran of the SLAC 40th anniversary celebration; the in support of milestone anniversaries and birth- SPEAR 25th anniversary celebration; and the NARA celebration days: their extra efforts are usually rewarded of the 50th anniversary of World War II; and that she is the proud recipient of a bottle of CERN’s 50th anniversary wine. with a better appreciation on the part of their

organization, and the public at large, of the rich symmetry | volume 03 issue 05 june/july 06 history of their parent organization; with higher visibility and use of the archives’ collections; with greater understanding of the archives’ mission; and with the addition of new, or—more accurately—newly re-discovered materials that further enrich the archival collections. New insights into and understanding of the histories of laboratories, and of the life and

9 A Report Like

Can the unique EPP2010 panel steer US particle physics away from its looming crisis? Physicists and policy makers are depending on it.

by Elizabeth Clements

Chuck Shank, former Director of Lawrence Berkeley National Laboratory (and not a particle physicist), carried the advocacy of the EPP2010 report to Fermilab. Shank told the crowd in Ramsey Auditorium: “I went from being an agnostic supporter to being truly excited about what you can do in this ﬁeld…The intellectual depth is just amazing.”

Photo: Reidar Hahn, Fermilab

10 No Other

An urgent joint summons in 2004 from the US Department physics occurred in 1998, Robin Staffin, Associate of Energy and the National Science Foundation described Director of High Energy Physics in the US Department an imminent crisis in the field of particle physics. of Energy’s Office of Science; and Michael Turner, Responding to the request, the National Research Council then-Assistant Director for Mathematical and Physical proposed a risky experiment: forming an advisory panel Sciences in the National Science Foundation, saw with broad representation within and beyond the science the need to advance the schedule for a new study. In community, and with particle physicists in the minority. November 2004, they charged the EPP2010 committee When this advisory panel, known as EPP2010, set out to: “Identify, articulate, and prioritize the scientific ques- on its investigations in late 2004, the membership included tions and opportunities that define elementary-particle an economist and president emeritus of Princeton physics. Recommend a 15-year implementation plan with University as chair; three Nobel Prize winners (two in realistic, ordered priorities to realize these opportunities.”

Physics, one in Medicine); the former CEO of a technology Five years of flat federal funding, the start-up of symmetry | volume 03 issue 05 june/july 06 giant; an astronomer; a former national laboratory direc- the Large Hadron Collider (LHC) in Europe in 2007, and tor; theoretical physicists; a former White House Office of increasing uncertainty about the future of US particle Management and Budget official; condensed matter physics made such a rigorous report a necessity. Jonathan physicists; a former Presidential science advisor; and an Bagger, an EPP2010 committee member and particle array of distinguished particle and accelerator physicists. physicist at The Johns Hopkins University, is a veteran of The hope: a panel with such a unique make-up would many advisory committees. In 2001, he co-chaired a DOE- have a wider impact than previous scientific committees. sponsored committee with International Linear Collider With the release of Revealing the Hidden Nature Global Design Effort director Barry Barish, producing of Space and Time: Charting the Course for Elementary a report with the first strong recommendation for the field Particle Physics in April 2006, the first indications are of particle physics to make the ILC a high priority. that the experiment was a success. “The difference between now and five years ago is that “This is an important opportunity for the US physics then, we were looking forward to Run II and the LHC community,” says the University of Chicago’s Vice-President was farther off on the horizon,” Bagger says, referring for Research and for Argonne National Laboratory, to Tevatron Collider Run II at Fermilab. “Run II is a reality Thomas Rosenbaum, who closely followed the release of now, and the LHC is looming. We are just that much the report. “There is the importance of the physics itself closer to the time of transition, and that certainly and its ability to attract and retain the best talent in the increases the urgency, the opportunity, and even the peril.” world. The report is particularly impressive because it was The status of the particle physics program within not made up of just particle physicists. Having econo- US laboratories has changed dramatically. The primary mists, biologists, and science policy makers on the panel mission of Stanford Linear Accelerator Center has lends additional credibility to the report.” broadened to include a larger program in light sources and astrophysics. Fermilab will soon be the sole remain- Issuing the charge ing US lab focused on particle physics. The cancellation Once every decade the National Academies’ National of particle physics projects such as BTeV and RSVP in Research Council brings together committees of experts 2005 left the United States without a major accelerator- in all areas of science and technology to review each based experiment to follow the eventual shutdown of field. These experts serve pro bono to address critical Fermilab’s Tevatron in 2009. Because of the dramatic national issues and give advice to the federal govern- transitions in the field, the EPP2010 committee’s report ment and the public. Even though the last study of particle recommends as a priority second only to fully exploiting

11 the opportunities afforded by the Large Hadron Collider at CERN, that the United States “do what is necessary to mount a compelling bid to build the proposed International Linear Collider on US soil.” Outlined in priority order as designated by EPP2010, the report recommends that Why is this report different from others? the United States: Reaching this unanimous conclusion, however, was not a simple process. Skeptical at first, several members of 1 Fully exploit the opportunities afforded by the con- the panel required a great deal of convincing with a struction of the Large Hadron Collider at CERN. number of presentations from particle physicists across 2 Plan and initiate a comprehensive program to the country before endorsing the recommendations for become the world-leading center for research and future plans. “It was a tremendous intellectual challenge development on the science and technology of to learn how to communicate with people who are not par- a linear collider, and do what is necessary to be able ticle physicists, and it made us really hone our arguments,” to mount a compelling bid to build the proposed says Sally Dawson, head of the physics department at International Linear Collider on US soil. Brookhaven Lab and vice chair of the panel. “I feel like we took a test and passed—maybe even got an A.” 3 Expand the program in particle astrophysics and Distinguishing the EPP2010 report from all other pursue an international coordinated, staged program reports is the diverse make-up of the panel and the in neutrino physics. multitude of reactions following its release. “They took a very brave position,” says Marc Kastner, head of the physics department at MIT and chair of the National Research Council’s Solid State Sciences Committee. “It Reporting on the Future The EPP2010 report (top left) is formally titled: Revealing the might be a gamble to say that the ILC is the thing that Hidden Nature of Space and Time: Charting the Course for we must do to maintain leadership in high-energy phys- Elementary Particle Physics. Stating unequivocally that the program ics, but they are probably right.” in US particle physics faces a crisis, the report strongly recommended a “compelling” effort for the US to host the proposed Dawson credits the success of the unique group to International Linear Collider. Also issued under the auspices of the economist and EPP2010 Committee chair Harold National Academies, the report Rising Above the Gathering Storm Shapiro, who sat through hours of tutorial sessions with (top right) describes the crisis in science and technology education in the US. This panel was chaired by Norman Augustine, also physicists. His devotion to the task further validates the a member of the EPP2010 panel. The DOE-NSF High Energy conclusions in the report. At the press briefing, Shapiro cut Physics Advisory Panel has commissioned two recent reports on to the chase in addressing the pending future of particle particle physics. Quantum Universe (bottom left) portrays a revolu- tion in particle physics, with nine critical and interrelated questions physics: “We came to the conclusion that this might be about the universe charting the course ahead. Discovering the the most exciting moment for the field,” he said. “Exploring Quantum Universe (bottom right) explores the role of particle col- the Terascale and having the technology to do it is more liders in answering those nine questions. compelling than ever.” The entire panel went through an educational process that converted members from observers of particle physics to true believers. “I went from being an agnostic supporter to being truly excited about what you can do in this field,” says Chuck Shank, panel member and former director of Lawrence Berkeley National Laboratory. “I realized that the Higgs [the particle thought responsible for giving mass to all others] is just the tip of the iceberg. The intellectual depth is just amazing.”

Risky vs. riskier Still haunted by the 1993 demise of the Superconducting Super Collider (SSC), a $10-billion project in Waxahachie, Texas that Congress cancelled in 1993, scientists recognize that if one ﬁeld of physics is strong, all of the other branches will beneﬁt (or vice versa). “If we learned anything from the SSC, it’s that when big projects in particle physics are cancelled, it doesn’t help anybody else in physics,” Kastner says. “We all sink or swim together.” Physicists in condensed matter and solid state physics, for example, are more likely to support the ILC if it does not follow the same path as the SSC. “It is critical that the ILC not get started and then have big cost overruns and be cancelled,” says David Tanner, a condensed matter physicist at the University of Florida and chair of the

12 US-based programneedtobedeveloped.”US-based Wayshard torestart. amodestbutexciting tomaintain high-energyphysicscomestoastop,itwillbe US-based If States. United the within conducted be will iments exper of alinearcollider, nootherfederally-funded HEP construction and design of period 20-year the during experiment atFermilab. “Itseemslikelythat MiniBooNE equally fatal,” saysJanet Conrad,co-spokespersonofthe being from ‘cure’ Collider Linear the prevent to how ing thehigh-energyfrontier;howeveritdoesnotaddress “This report proposes a cure for the ‘fatal disease’ of los- alack ofproposalsforintermediateprojects. about worry strongly endorses the push for the ILC, some scientists “complete.” not report is the While report the that cerns oftheSSC.” onbudget andnotrepeatthemistakes stay must it but community, science physics high-energy Matter Physics.“The ILC seemslikethenext stepforthe Condensed of Division Society’s Physical American implementation.” to next advisory committees and the funding agencies for over handed is report way, the that In priorities. the of implementation the in flexibility and latitude tremendous panelsandleft differently fromotherNRC oritized very operations ofthefield,” Baggersays.“This committeepri advisory process so that it gets built into the day-to-day PanelEnergy PhysicsAdvisory (HEPAP) and theofficial is howfartherippleswillspread. releasemadeabigsplash.The questionnow EPP2010 attention fromnationalandinternationalpublications,the acrossthecountry.and atlaboratories Attracting media inWashington, onacircuitoftalks members started DC, Immediately followingthereleaseofreport,panel thereport Beyond now.” right are we where stay is do can we that thing riskiest find,”“The could says. we Shapiro that risky least the is it but investment, risky a is “It in theeyesofpanel,ILC isariskworthtaking. And returns. large yield can risks large terms, economic ics programcanbeconsideredrisky. Butspeakingin Ordaining theILC asthefutureforUSparticlephys will make up the next generation of particle physicists. who students graduate the of views the solicit to point ILC doesn’t happen,thenwhat?Isthatit?” expense of the neutrino program or other projects? If the when youplaceallofyourbets ontheILC. Isitatthe ple isthelack ofintermediatejobsintheUS,especially in responsetothereport.“The concernforyoungerpeo experiment, CDF Fermilab’s of member and Michigan of University from student graduate a Copic, Katherine non-physicists,” to says why and doing are we what communicated panel the on physicists the that know to good very is “It States. United the in field the of future long-term the about concern a share papers, publish to and theses their complete to data with experiments running require who postdocs, and students graduate Some inthecommunity,Some however, haveraisedcon High the by embraced be will it that is hope “Our a it made panel the world-tour, laboratory their On US horizon, the on projects intermediate no With

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13 prevent a report from just collecting dust on a bookshelf. expert legworkto whenitcomestodoingthenecessary an is address, Union the of State annual President’s US the influenced and October in headlines made that report Academies National the of head Augustine, Norman long-term. and real be will impact its that EPP the promote will community physics particle US the of members meantime, the In Rising abovedifferences Europe andtheentireglobalcommunity. a majorimpactonnationalscienceprogramsthroughout report. Council’s The recommendations CERN will have ment that will be the European equivalent of the EPP Council Strategy Group will issue a draft strategy docu 2006. September by Foundation Science National the and Energy of Department P States. United the in budgets their and projects specific prioritizing level, P foundation, a as report cle physicsoverthenext decade.UsingtheEPP Panel (P attacking eachattacking other.” to presentthecasetogether asacommunity, without country what this is and why it is important.” He adds: “Try this in budget the control who people the and public the tell to now groundwork the building “Start munity: the on talks 30 some given EPP the of Alsoamember becomesinevitable. crisis inthiscountry and outsources science and engineering jobs, economic argued thatasAmericafallsbehindinscienceeducation Even before thereleaseofP Prioritization Project Physics Particle the up, Next Augustine’s advice for the US particle physics com physics particle US the for advice Augustine’s Augustine’s report, 5 ) will propose a detailed roadmapforUSparti ) willproposeadetailed 2010 panel, Augustine estimates that he has has he that estimates Augustine panel, Rising Above the Gathering Storm 5 will submit a final report to the the to report final a submit will 5 Photo: DianaRogers,SLAC the field.” momentfor most important conclusion thatthismightbethe declared: “We cametothe Emeritus ofPrinceton University, economist andPresident Harold Shapiro,committeechair, will take the plan to the next next the to plan the take will Gathering Storm Gathering

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symmetry | volume 03 | issue 05 | june/july 06 Successful launch at Oak Ridge: six labs collaborate on the largest unclassiﬁed science construction project in the United States. SNS: By Bill Cabage Neutrons for ‘molecular movies’

Image source: ORNL, Sandbox Studio 14 The scene is reminiscent of Mission Control for a 1960s Why neutrons? Why the SNS? space shot—minus the skinny ties, pocket-protectors, When a fast particle, such as a high-energy proton, bom- and cigarette smoke. But the intensity in the control bards a heavy atomic nucleus, some neutrons are “spalled,” room at 1:30 in the afternoon on Friday, April 28, 2006 or knocked out from the nucleus, in a nuclear reaction approximates that of a lunar landing. called spallation. Other neutrons are “boiled off” as the The eyes of operators, project managers, and a few bombarded nucleus heats up. It’s something like throwing special guests track the numbers and graphs on control a baseball at a bucket of balls, resulting in a few being monitors. DOE’s Spallation Neutron Source at Oak immediately ejected and many more bouncing around and Ridge National Laboratory is about to attempt to send falling out. For every proton striking the target nucleus, a beam of trillions of protons to a target. If the effort 20 to 30 neutrons are expelled. Wave guides channel succeeds, it will mark the completion of a seven-year, beams of spalled neutrons to instruments that probe mate- $1.4 billion effort, the United States’ largest unclassified rial structures and properties. science construction project. Neutrons are abundant in the universe, making up Among the furrowed brows in the control room, Jack more than half of all visible matter. But for research on Carpenter’s smile stands out. Wearing a navy blazer, physical and biological materials, neutrons of the right with an expensive-looking camera around his neck, brightness are in short supply. Just as we prefer a bright Carpenter is a special guest. He gets credit for proposing, light to a dim one to read the fine print in a book, back in the 1970s, the idea of a spallation neutron source researchers need a bright source of neutrons that will that would combine the advantages of a pulsed neutron give detailed snapshots of material structure and make source with time-of-flight neutron scattering instruments— “movies” of molecules in motion. The SNS will provide the key concepts at the core of the SNS. He’s often these bright neutrons. Like a flashing strobe light provid- come to Oak Ridge from Argonne National Laboratory to ing high-speed illumination of an object, the SNS will help with the project. Now launch day is here. produce pulses of neutrons every 17 milliseconds, with symmetry | volume 03 issue 05 june/july 06

15 more than 10 times more neutrons than are pro- The applications of neutron scattering seem duced at the most powerful pulsed neutron almost limitless. Neutron scattering probes the sources currently available. Like water spraying behavior of internal magnetic fields in advanced from a rock splashed by a garden hose, neutrons high-temperature superconducting materials from a beam “scatter” from a target material such as yttrium-barium-copper-oxide, allowing in a way that reveals its structure and properties. scientists to view these fields directly. Neutron Why pulsed neutrons? To analyze the results scattering also reveals the structure and molecular- of neutron scattering, scientists need to know level dynamics of semiconductors used in the the initial energy of the neutrons spraying off the race to develop new materials for the electronics material they are studying. When all the neu- industry. Small-angle neutron scattering—aiming trons leave the starting gate at the same time— the garden hose just so—can reveal clusters as in a pulse—the time it takes each neutron to small as 50 atoms that form, for example, in the reach the target material—its time of flight—is steel of reactor pressure vessels after years of known, revealing its velocity and hence its exposure to radiation from the reactor core. The energy. With this key piece of information on neutrons can show whether heat treatment neutron energy, scientists can interpret what removes defects from the irradiated steel, making neutron scattering is telling them about a mate- it less brittle and less susceptible to failure. rial under study. In contrast, neutrons from a reactor leave the source continuously, rather Something new? than in a single pulse, making time-of-flight With a beam power of 1.4 megawatts, the SNS will energy determination impossible. become the world’s leading facility for neutron Although there are fewer accelerator-based scattering research—eight times more powerful neutron sources than reactor-based sources, than next-brawniest ISIS. A power upgrade and accelerator-based pulsed spallation sources second target station—with a different assortment represent the state of the art. Japan’s J-PARC of specialized instruments to add to its 24 beam- will have a spallation source coming on line in lines—are already on the DOE Office of Science 2008–2009 with one-megawatt power. The drawing board. UK’s Rutherford Laboratory is upgrading the The development of the neutron as an ana- ISIS facility to give it a power boost and a lytical tool came largely as a spin-off from World second target station. War II weapons research. The initial discoveries

Deuteron

Secondary Neutron

Primary Proton Nucleus γ Ray

π Particle Spallation Product

To produce neutrons, scientists smash protons into a material α Particle made of heavy atomic nuclei, which contain many protons and neutrons. Each collision shakes loose some neutrons and other particles, a process called spallation. The secondary particles hit surrounding nuclei and create even more neutrons.

Source: ORNL

16 were made at Oak Ridge, originally a pilot plant Six-lab partnership for the reactors that would produce plutonium The SNS rose from the ashes of a reactor project. for the Manhattan Project. Scientists working at Scientists had proposed the Advanced Neutron Oak Ridge’s Graphite Reactor realized that light Source, a research reactor to succeed ORNL’s atoms as well as heavy ones could be probed High Flux Isotope Reactor, with state-of-the-art by exposure to neutrons. Two researchers, Ernest beamlines and instrumentation tailored particularly Wollan and Clifford Shull, approached ORNL’s to the mission of neutron research. When con- then-scientific director, the esteemed Eugene cerns over its $3-billion-plus cost and highly Wigner, with their work. “Maybe there is something enriched uranium fuel doomed the project in the new here,” Wigner remarked. mid-1990s, DOE’s Office of Science decided Now neutrons are a favored tool for investi- to pursue instead a more affordable spallation gating the properties of materials. Because a source located at Oak Ridge. neutron is electrically neutral—hence its name—it Project organizers developed an innovative can penetrate deep into a material. Unlike the plan to involve five DOE national laboratories in case of X-rays, the probability of neutron scatter- the design and construction of the project. ing does not depend on the number of protons The original partnership of Lawrence Berkeley in a material’s nucleus, so it can probe light ele- National Laboratory, Los Alamos National ments as well as heavy ones. Neutrons easily Laboratory, Brookhaven National Laboratory, reveal hydrogen atoms, a capability especially Argonne National Laboratory, and Oak Ridge useful in studying biological materials. National Laboratory represented one of the Neutrons are magnetic; the size and direction largest of its kind in US scientific history. Each of a neutron’s magnetic field is called its magnetic laboratory would design and build a key SNS moment. Beams of neutrons can be polarized component. Oak Ridge, the home base, would according to their magnetic moments and used put them all together and make it work. to investigate the magnetic properties of materials. The range of energies represented in thermal and chilled neutrons (those with short and long Top: Operators remotely maintain the SNS target wavelengths, respectively) makes them ideal for area. Bottom: The linear accelerator of the SNS is analyzing soft materials such as proteins and 330 meters long. polymers. Photos: ORNL The SNS will provide neutrons that are bright enough to create detailed characterizations of material structures, from crystals to DNA molecules; and to make “movies” of molecules in motion. Neutrons complement X-rays in studying proteins for critical information in pharmacology, agriculture and biotechnology. Determining the structure of enzymes in the human body, for example, will speed the development of more effective drugs. symmetry | volume 03 issue 05 june/july 06

17 Work began at the end of 1999. During the Researchers will use the Powder Diffractometer, planning process, advances in superconducting the most flexible and versatile of its kind, for study- technology led to the addition of a supercon- ing small samples and performing parametric—or ducting section to the SNS’s linear accelerator, effect-over-time—experiments. The Backscattering which would operate at a temperature two Spectrometer will probe atomic-scale dynamics degrees above absolute zero and greatly improve at high resolution, providing data up to 100 times the machine’s efficiency. Thomas Jefferson faster than existing instruments. Probing the National Accelerator Facility, which helped pio- dynamics of atomic or molecular motion is impor- neer superconducting accelerator technology, tant for materials with large surface areas. would deliver the cold section, completing the Researchers will use the Ultra-High Pressure six-lab collaboration. Diffractometer to study atomic structures at An SNS first is its target station, a modular ultra-high pressures equal to those found deep unit that recirculates 20 tons of liquid mercury. in the earth or in brown-dwarf stars. A Disordered Designers realized that mercury’s neutron-rich Materials Diffractometer will be used for small- atoms would be ideal receivers for the SNS’s angle studies of atomic structures of glasses and powerful, pulsed proton beam, which spalls neu- liquids, while the Single-Crystal Diffractometer trons from the nuclei of mercury atoms. will be optimized for rapid data collection from very small crystals, crucial for characterizing the Instruments of discovery large number of materials for which it is impos- Scientists from around the globe will come to sible to grow large crystals. do experiments using the instruments stationed The SNS will have a class of spectrometers on the 24 SNS beamlines. Some 2000 users called “choppers,” so named because a mechan- annually will be selected by Oak Ridge through ical device interrupts the neutron beam and a peer-reviewed proposal system. allows only neutrons of a certain energy to reach The SNS will have two highly specialized the sample. The speed of the neutrons as they instruments known as reflectometers. The bounce back from the sample gives researchers Magnetic Reflectometer is designed for studies the data they need to analyze the characteristics of thin films; the Liquids Reflectometer will, not of the materials. surprisingly, study liquids. The SNS beam intensity These chopper spectrometers offer research- will allow the added dimension of “off-specular” ers enhanced sensitivity, broader ranges, and measurements—that is, measurements of molecular structures parallel as well as perpen- dicular to the surface. The Extended Q-SANS (Small Angle Neutron Scattering) Diffractometer can cover a range of spatial scales from several hundred angstroms to a fraction of an angstrom in one measure- The SNS target station circulates 20 tons of liquid ment. The Extended Q-SANS instrument, with mercury, a material that contains a large number its ability to analyze multiple scales at once, of neutrons per atom. When hit by protons, neutrons will be especially suitable for studying complex emerge from the liquid and travel to the surrounding experimental areas with their instruments. materials, particularly biological samples such as cell components. Photo: ORNL

18 improved intensity, in some cases by factors of Staffers gather in the lobby of the SNS Central approximately 100. They include the High- Laboratory. Project Director Thom Mason and Resolution Fermi Chopper Spectrometer, opti- ORNL Director Jeff Wadsworth stand on a stair- mized for single-crystal studies; the Wide-Angle well holding plastic flutes of champagne to lead Fermi Chopper Spectrometer, a lower-resolution the gathering in a toast to success. The Physics- instrument for wide-angle studies; and the 10-100 Diagnostics Station electronic logbook entry Microvolt Multi-Chopper Spectrometer, a flexible reads: “Here is what so many have labored toward general-purpose analytical tool capable of sending for so many years.” up to 100 times more neutrons to the sample. Clifford Shull, who, in the 1940s, along with Finally, the SNS will have a beamline dedicated Ernest Wollan saw the potential of neutrons for to the study of the neutron itself, addressing exploring the structure of materials, lived to questions about the big-bang theory and phys- share the 1994 Nobel Prize for his work in neu- ics beyond the Standard Model of particles and tron scattering. Shull also saw the beginnings their interactions. of the new neutron research facility on a ridge top in Oak Ridge overlooking the old reactor Wigner was right where he had worked just after the war. As the At 3:30 p.m., the control room at Oak Ridge breaks prescient Eugene Wigner foresaw, the SNS out in a roar. There is lots of back-slapping, hand- represents a long-awaited “something new” for shaking and cheering. The SNS, an hour and a the neutron science community. half after producing its first neutrons—and a first “We’ve come a long way,” says Jack Carpenter, round of cheers—has delivered its 1013 protons the control-room guest who proposed the SNS to the target—the beam power mark that signals idea more than 35 years ago. “I would have never official completion. envisioned how far.”

Instrument

The Spallation Neutron Source will deliver high- intensity neutron beams to a variety of instruments that feature special detectors to examine the Sample interaction of neutrons with biological samples or other materials. Detectors

Source: ORNL

Neutron Guides

10–80 meters

Moderator A moderator slows down the neutrons produced in the spallation process and illimi- nates a neutron guide. symmetry | volume 03 issue 05 june/july 06 Target Nucleus

Energetic proton When a high-energy proton bombards a heavy atomic nucleus, causing it to become excited, 20 to 30 neutrons are expelled.

19 Creating and then annihilating the tiniest and most powerful beams of electrons and positrons ever produced, the proposed International Linear Collider could open pathways to new particles, new dimensions, and new discoveries beyond our current imagination. But clouds could block the view. Like clouds of ice crystals or condensed water droplets ﬂoating in the sky and blocking the sunshine, these clouds of electrons could dim the accelerator’s brightness and block the view of new discoveries. Within the global effort to make the ILC shine brightly, Mauro Pivi of Stanford Linear Accelerator Center wants to channel these electron clouds into a gutter inside the machine. Lanfa Wang, also of SLAC, wants to attract and dissipate them with an electrical charge. Each is clear about the stakes: prospects for building the multinational, multi-billion-dollar ILC depend signiﬁcantly on its cost, and its cost depends in part on removing the clouds. “If we manage to cure the electron cloud problem,” Pivi says, “we could save one damping ring and hundreds of millions of dollars.”

20 Lots of collisions Physicists have built particle colliders for more than half a century, but designing a collider as complex as the up-to-40-kilometer-long ILC brings up lots of new questions along the way. To catch a glimpse of the universe’s fabric at the smallest possible scale, the ILC uses beams of tightly-packed electrons, smashing them head-on into beams of tightly- packed positrons, the antimatter counterparts of electrons. To maximize experimenters’ chances of making discoveries, the machine must produce as many collisions as possible. Accelerator physicists achieve this maximum by squeezing the largest number of particles into the smallest possible space, hurling these tiny, high-density packages of particles toward each other at close to the speed of light. When an electron in one Sending high-density pack- bunch hits a positron from another, the resulting annihilation provides ets of positrons through a the energy that creates new particles and exposes new forces. beam pipe produces electron clouds that diffuse the Making these high-intensity bunches, then shrinking them to a size one positron beam. ten-thousandth of the thickness of a human hair, is a science of its own. Starting at opposite ends of the ILC collider, the initial bunches of electrons Illustration: Sandbox Studio and positrons are far too diffuse to be of experimental value. Separate machines called damping rings, which are several kilometers long, transform loose streams of particles into tight, disciplined beams before their final acceleration toward the collision point at the center of the ILC. The design of the damping rings is determined by three factors: accom- modating the desired number of electron and positron bunches, meeting the stringent requirements for the size of the beam, and finding the least expensive solution. But before the final design can be approved, someone has to find out how to handle the electron clouds.

Cloud problems The electrons and positrons of the ILC travel along the center of vacuum beam pipes. Whenever they change direction, they emit light that hits the metal wall of the beam pipe and kicks out electrons from the atoms in the wall. The positron beam attracts these negative electrons, providing them with additional energy: the electrons bounce around inside the beam

pipe, repeatedly hit the surrounding wall, and cause an avalanche of addi- symmetry | volume 03 issue 05 june/july 06 tional electrons. “These electrons hit the wall and they multiply,” says Pivi. “From one electron they become two. Then four, eight, sixteen, thirty-two—after a little while you have a cloud of electrons and you cannot get rid of them.” Pivi is part of the international team designing the ILC damping rings. Together with his colleagues, he is working on a solution to the “electron cloud effect,” which diffuses the positron beam. The positrons are attracted to the surrounding negatively-charged electron cloud, causing

21 the positron beam to grow in size and sometimes even to wobble out of control. Such a beam would be too large and too diffuse for the main accelerator of the ILC, and would produce too few collisions. In existing electron and positron accelerators with low beam intensity, the clouds have been relatively easy to control. Wherever possible, electrically charged coils are wound around the beam pipe to trap the troublesome particles near the wall, leaving a clear path for the beam. For the ILC with its high-intensity beams, damping rings do not offer enough room for the same kind of coils. Scientists need to ﬁnd a new technique to brush the particles aside or they will have to eliminate the clouds altogether.

Bigger rings mean thinner clouds To combat the electron clouds, ILC designers looked at the optimal size and shape of the damping rings. Electron clouds only grow thick if positron bunches follow each other machine-gun-style right one after another. If designers increase the distance between the bunches by using a longer damping ring, the clouds are thinned. To give the bunches the preferred extra space, one initial design sug- gested a massive damping ring for the positrons shaped like a telephone receiver, about 17 kilometer in circumference. The sheer size of this ring, nicknamed the “dog bone” by physicists, would spread the bunches enough to eliminate any opportunity for the clouds to form. However, the dog-bone configuration is expensive, and Yunhai Cai, a SLAC physicist overseeing part of the design, says it doesn’t push scientists toward an innovative solution. Instead, ILC scientists are favoring two six-kilometer-circumference damping rings for the positrons. Each ring would handle one half of the total number of positron bunches, and the two rings could sit on top of each other in one tunnel, reducing the cost of construction. “The reason we want two rings is because we want the bunches separate enough so the electron cloud is not a problem,” Cai says. “If you only have space for damping two bunches, then you can only provide two collisions. If you have space for 3000, you are much better. It’s like bullets. The faster you can get them out, the better. But those bullets have to be really good bullets. You want them really sharp.” Cai also points out that a double-circle shape is an efficient, symmetrical design. However, while building two large rings will solve the electron cloud problem, in some ways it’s an expensive quick fix. Cai says more creative and permanent solutions are needed.

“If we manage to cure the electron cloud problem, we could save one damping ring and hundreds of millions of dollars.” Mauro Pivi

SLAC physicist Mauro Pivi and his colleagues are testing new technologies that may reduce the electron clouds in beam pipes. This prototype beam pipe is outﬁtted with grooves that trap electrons before clouds can form.

Photo: Diana Rogers, SLAC

22 A ‘groovy’ alternative What if scientists could get rid of the clouds altogether? Without the clouds, researchers could envision an ILC damping ring as small as three kilometers around to bring the electron and positron bunches into shape. The design would require loose electrons to be absorbed before they recruit more. Inspired by his colleagues Alexander Krasnov and Gennady Stupakov, Pivi has devised a solution featuring rectangular grooves cut into the chamber walls to trap the errant electrons. As the electrons bounce off the walls, Pivi’s grooves capture them: like golf balls being tossed into a rain gutter, the electrons bounce around inside a groove, lose energy, and are absorbed by the surface of the grooves. Pivi has designed and tested several models, one for the straight sections of the damping ring and others for those that curve. Grooves in the straight sections would be about one millimeter deep, while those on the corners would be a tenth that size—roughly the size of a strand of spaghetti versus a strand of human hair. Pivi is testing his larger grooves in the lab. By aiming a beam at several one-square-inch plates with grooves, he can see how well the grooves trap electrons. So far, results have been good. Without grooves, the secondary yield of the walls is about two: for every electron that hits the wall, two bounce back. With grooves, yields are down to 0.6, meaning fewer electrons escape than go in. The next step will come this summer when Pivi begins experiments using the larger grooves at SLAC’s PEP-II accelerator facility. “The latest lab measurements were great,” Pivi says. “We got what we expected. When we install chambers with these grooves in PEP-II we will see if there is an electron cloud or not. This will be the test.” The spaghetti-sized grooves are inexpensive and can be machined relatively easily. However, the tiny hair-sized grooves might present a challenge. Each panel of hair-sized grooves must be precisely cut, and the higher cost of the panels might make them prohibitively expensive.

An alternative approach Across the hall from Pivi, Lanfa Wang proposes a different solution to get rid of electrons. Rather than trapping the electrons, he plans to bribe them into leaving. “If we want to kill the electrons in the central region of the chamber, we should put in a strong electrode,” Wang says. Electrodes are electrical conductors through which a voltage can be applied to the surrounding area. In the case of Wang’s solution, a clearing electrode creates a positive charge along the interior of the beam pipe that is strong enough to pull electrons away from the center, creating a clear path for the positron beam. Out of reach of the beam, the particles slow down and dissipate. Scientists at the European laboratory CERN will test a similar promising technique using proton beams, but the method has never been used with the much lighter electrons and positrons so far. Wang and Pivi hope to test an optimized electrode design in SLAC’s PEP-II as early as this summer. At present, it remains to be seen how successful the various damping ring designs will be. Wang says if the electrodes meet his expectations, it might be possible to eliminate one of the two positron damping rings cur-

rently envisioned for the ILC, reducing the cost of the machine. The most symmetry | volume 03 issue 05 june/july 06 likely solution may be a combination of the two technologies. “There are many solutions,” Pivi says. “We have good artillery against the electron clouds. We will test all possibilities.” The best solution, of course, will be the one that provides the most unclouded view for the machine, and thereby for the science ahead.

23 A M a g n u s Force on the Mound Major league pitcher Jeff Francis brings an educated insight to the physics of baseball. by Mike Perricone

The Magnus force has made Jeff Francis what he is today: a 25-year-old left-handed pitcher on the rise in his second full season with Major League Baseball’s Colorado Rockies. A former physics and astronomy major at the University of British Columbia, Francis could hold court for the Rockies’ pitching staff and coaches to discuss the Magnus force and its deviational effects on the path of a 5.25-ounce baseball spinning through the air with a forward velocity of more than 90 miles per hour (or more than 132 feet per second), over a distance of 60 feet, six inches. Francis could clarify what puts the curve in a curveball, the “hop” in a fastball, the slide in a slider, the sink in a sinker. But he won’t be giving that talk any time soon. “As much as it might seem contradictory,” Francis says, “physics knowledge does not help much on the field. So much of playing baseball is ‘feel’ that explaining to someone what makes a ball curve would be almost meaningless. I get asked that a lot, and sometimes I say: ‘I never met him, but I bet Einstein couldn’t throw a curveball.’” On the other hand, Einstein did toss a memorable and gigantic curve at physicists’ concepts of matter, space, and time a hundred years ago. Francis is good, but he hasn’t yet matched that impact. At six feet, five inches tall and 200 pounds, the Canadian-born Francis would be a dominating presence in physics labs or lecture halls. On a baseball field, however, he is practically willowy. Most major league pitchers of his height (for example, Kerry Wood and Mark Prior of the Chicago Cubs) are 25-to-30 pounds heavier with a consequently more imposing appearance as they stare down at a hitter from the pitcher’s mound. But delivering a pitch is all about physics: the most efficient transfer of momentum from body to baseball; the maximum effectiveness of the arm as a lever; the rotational dynamics of the baseball leaving the fingertips. And within four-tenths of a second after Francis delivers a pitch, the batter faces his own challenge of physics and mechanics. In The Physics of Baseball, Robert K. Adair (Sterling Professor Emeritus of Physics, Yale University; Official Physicist to baseball’s National League, 1987–89) says a batter must react in less than one-fourth of a second. In the one thousandth of a second of bat-ball contact, Adair says, a superlative hitter such as Albert Pujols of St. Louis will deliver some 8000 pounds of force, compressing the ball to about half its original diameter—that is, if Pujols meets the ball precisely on the bat’s “sweet spot,” or vibrational node (point of no vibration), after analyzing and reacting to the Magnus force effects on the pitch thrown by Francis. The Magnus force was identified in 1852 when the German physicist Gustav Magnus demonstrated that a spinning object moving through

24 ficient tolifttheball,butsufficientdelivera fastball—the Magnusforceactsupward;notsuf Pujols).toward aright-handedbatter(advantage, Francis)from aleft-handed batter(advantage, but left away torightashewatches hisowndelivery; ball ofaleft-handed pitcher likeFrancis breaksfrom direction ofthespin.The sideways-spinningcurve and apitch withsidewaysspinwilldeflectinthe velocity andtotheaxisofspin.Atwistwrist, forceactsatrightanglestothedirectionofair tant tor isgreaterthanthevelocityofotherside.” The resul velocity throughtheairofonesideballatspinequa- a explains, Adair As path. its in deflection sideways a experiences fluid a research? Idon’tknowforsure.ButI’mhappywhereamright now.” interestedin…Maybeacareer in cancertreatment gram, which Iwasvery inscience,Francistaken muses:“At there isamedicalphysicspro UBC have might he direction a lectures.” about his of Asked some remember theclasses insuch greatwaysthat to thisday,says, “whotaught Istill on themound,thoughphysicsisanactivememory. itselfasaforceful presence.Hisheadandheartare team establishing onayoung Colorado in2002.Heisregardedasapitching mainstay ball tookprecedence,andhesignedhisfirstprofessional contractwith undergraduate majorattheUniversityofBritishColumbia.But base came easilytohiminhighschool,math, andchemistry leadingtohis “I can’tget anymorecrosswordcluesthananyoneelse.” Physics, beinganintellectual, although often teasehimgood-naturedlyabout turn, meanstheballwilljumpoffbatmore.” means ahigherfrequency, which meansharderwood,which, in then listeningtoitlikeatuningfork,knowingthathighersound theirbatwithhandand ple, you’llalwaysseehitterstapping being aroundbaseballandobserving,” Francis says.“For exam just by game the of aspects physical certain of aware are not, physicists. intuitive also are hitters that Francisobserves on thewaytowardsbatter.” regular amount,theballgivesillusionofrising Since theeyeissousedtoseeingitdrop fractionoftheregulardistance. a certain longer onthewaytohomeplate,dropping theaircanholditupjustabit is obtained, towards homeplate.Iftherightbackspin so thatit’sintheaironitsregularflight amountinthequarter-secondor a certain [is] an optical illusion. Normally, the ball drops ball’s flighttowardtheplate.The ballrising Baseball of class,” Francis recalls.“We read withanothersoftballplayerinthe presentation out Iwasaballplayer, andaskedmetodoa tion ofwhether afastballcouldactuallyrise. intotheques once conductedhisowninquiry Francis plate. the to way its on “hop” perceived spinning baseballexperiences animbalanceofforcesbecause“the On apitch withbackspin—the conventional Matthews,” Jaymie Francis named UBC] [at professor great a had “I Francis hisphysicsbackground saysteammatesknowingabout or “I thinkallbaseballplayers,whether they’resuperstars “hop,” the under but swing will hitter the Sometimes “My second-yearmechanics professor found , and one chapter was about the the about was chapter one and , The Physics

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Major League Baseball Photo courtesyof

symmetry | volume 03 | issue 05 | june/july 06 deconstruction: spallation neutron source

research has improved the quality of many everyday items: Neutron scattering Shatter-proof windshields, credit cards, pocket calcula- tors, airplanes, compact discs, and magnetic storage tapes are just some examples. Probing materials and biological samples with neutrons, scientists have learned more about high-temperature superconductors, aluminum bridges, lighter and stronger plastic products, and pharmaceuticals. The increasing demand for more and better neutron sources has led to the construction of the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory in Tennessee, designed and built by a partnership of six US Department of Energy national laboratories.

The linear accelerator of the SNS, about 330 meters long, speeds up the hydrogen ions with electric fields that provide a cumulative voltage of one billion volts. Along the way, a foil strips the electrons from the ions, leaving behind a beam of protons. The SNS linac is the first machine to accelerate protons using superconducting technology, featuring doughnut-shaped cavities that con- duct electrical currents without resistance. Operating at a temperature close to absolute zero, these high-tech devices provide extremely efficient acceleration, minimiz- ing the length of the SNS proton accelerator.

Neutrons are the neutral building blocks found The target area is surrounded by experimental sta- inside atomic nuclei. To produce beams of neu- tions with “instrument systems” that use neutrons for trons, scientists accelerate charged particles and scientiﬁc experiments and industrial development. smash them into heavy atomic nuclei containing When complete, the Spallation Neutron Source will lots of neutrons. The collisions shake loose the accommodate 24 experimental areas, used by neutrons in a process called spallation. At the researchers in physics, chemistry, biology, materials SNS, a front-end system provides a stream of science, and engineering. In contrast to X-rays, which negatively charged hydrogen ions (each ion con- cannot penetrate metal or dense materials, neutrons sisting of one proton and two electrons). traverse virtually all types of materials. With neutrons, scientists can determine molecular structures and observe the motion of atoms. The brightness of the SNS will yield snapshots with higher resolution than achieved at older neutron sources, and the high repetition rate of the SNS neutron pulses will allow for the recording of “movies” of molecules in motion.

26 Six national laboratories—Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge—designed and built the Spallation Neutron Source, which cost US$1.4 billion. Funded by the Ofﬁce of Science of the Department of Energy, the construction of the facility took seven years; the ﬁrst production of neutrons took place on April 28, 2006. The SNS is open to scientists and engineers from universities, industries, and government laboratories in the United States and abroad.

Graphic: Spallation Neutron Source Text: Kurt Riesselmann; SNS fact sheet

Neutron sources based on nuclear reactors provide a In the target hall, sixty times per second, batches of steady stream of neutrons. In contrast, accelerator- protons strike a container ﬁlled with liquid mercury. Like based neutron sources such as the SNS can provide a baseball hitting a bucket ﬁlled with tennis balls, each pulses of neutrons. To create pulses, the SNS has proton entering the mercury causes the emission of a storage—or accumulator—ring that collects the protons neutrons: some neutrons are ejected immediately with emerging from the linac close at the speed of light and high speeds; other neutrons rattle around for a while sends them a short time later, when enough protons before leaving the mercury container at lower speeds. have accumulated, to a neutron-rich target. For every proton striking a mercury nucleus, about 20 neutrons are expelled. symmetry | volume 03 issue 05 june/july 06

27 gallery: ellis paul

Ellis Paul performs annually at the Woody Guthrie Folk Festival in Okemah, Oklahoma, birthplace of Guthrie, who was also a frequent opponent of orthodoxy. Paul also performed at Guthrie’s posthumous induction into the Rock-and-Roll Hall of Fame in 1996.

Photo courtesy of Ellis Paul

‘Did Galileo Pray?’ The sighting of Jupiter’s moons by Galileo Galilei resonates through science and history. Using a handmade telescope in January 1610, Galileo confirmed the Copernican theory that the planets moved around the sun; the Earth was not the center of the solar system. Galileo veri- fied a new truth, and threatened the orthodoxy of his time. Nearly four centuries later, while NASA’s Galileo mission was beaming back close-ups of Jupiter’s moons, folk musician and songwriter Ellis Paul began reading about astronomy. With a newly-purchased telescope, he gazed into the clear night sky above Boston in January 1998. He Portrait of Galileo, rediscovered Galileo’s new truth, and did what a songwriter does. The Assayer (1623). Writing “Did Galileo Pray?” Paul envisioned the inner conflict: Could Galileo embrace both science and faith? Could he continue to pray? After releasing the song, Paul received an invitation from the renowned History of Science Collections of the University of Oklahoma Libraries. “The curator brought me in because of the song,” Paul says. “She showed me one of Galileo’s original manuscripts of the Dialogue. She handed the book to me. It was the original edition, Galileo’s copy of the book. I was holding it. He had written his name on the book…I saw his notes, his crossouts. It was completely mind-boggling.” Paul links Galileo with civil rights marchers in the 1960s, and the student stopping a tank in Tian’anmen Square in 1988. “I picture that student stepping in front of the tank as a way of really going head-to- head, of putting his life on the line for change and understanding and truth,” Paul says. “Galileo went before the tanks of his day—the Catholic Church. Martin Luther King went before the racists, and a few hundred years of American history, by stepping right to the front of that line marching in Birmingham. I celebrate those people who confront the old way, who take that bold step, going head-to-head.” Paul admits his lyrics are slightly off-target: “Did he know…a prison cell / Would be where he’d lay his head down?” Galileo’s sentence of life imprisonment for disobeying the Church was com- muted to house arrest. Paul remembers his chagrin during one performance: “Some Columbia University students sat there shaking their heads at me.” But scientists are still going head-to-head with society over stem cell research, global warming, and even evolutionary biology. “The truth is in front of us all the time, that’s the thing that’s amazing to me,” Paul says. “The mathematics was there, the sky was there. It was just a matter of time before the truth came out through Galileo. The world was enlightened, but it took the Catholic Church until 1992 to forgive Galileo. That’s how the planet works, it seems. The truth gets in front of people, it gets too obvious to ignore, it beats people over the head, and still it takes some braver soul to be the poster child for the truth. There aren’t many like that through history. But Galileo, Martin Luther King, the student at Tian’anmen—they’re in that heroic vein.” Mike Perricone

28 Did Galileo Pray? by Ellis Paul

When he looked Into a starry sky upon Jupiter, With its cold moons Making their weary rounds. Did he know that the Pope Would claim that he ran with Lucifer And a prison cell Would be where he’d lay his head down? Was he wearing a thorny crown? When he plotted the motion of planets, Was Mercury in retrograde? But he found the truth when a lie was what was demanded. When the judges asked him pointedly He was a’ trembling that day. Chorus Did Galileo pray? Did Galileo pray? Did Galileo pray? Did Galileo pray? And he said, Tell Ptolemy, tell Copernicus, That the Sun is at the core of us The Church, the Pope Can’t deny the Milky Way And every ﬂower that follows the sun, Has known all along What God had done They whisper truth As the seasons each give way. Don’t shoot the messenger, The postman delivers Truth today. And Truth will march in Birmingham It will block the tanks in Tiananmen. Put the judges on the witness stand Let’s see what they all say. Chorus In the heavens you’ll see it As God has conceived it. Oh, believe it. Oh, what have you got to do to believe? Don’t shoot the messenger, Top image: Dialogue on the Two Chief World Systems (1632). Aristotle and Ptolemy (left) hold an Earth-centered armillary When the postman brings you truth today. sphere. Copernicus (right), holds a Sun-centered model Because truth will march in Birmingham of the solar system. It will block the tanks in Tiananmen symmetry | volume 03 issue 05 june/july 06 Middle image: In the Oklahoma Dialogue, the annotation in Put the judges on the witness stand, Galileo’s handwriting on the right page says the figure about Let’s see what they all say. falling bodies is upside down.

Bottom image: This page shows a new sentence by Chorus Simplicio to go before a long paragraph by Salviati, again Don’t shoot the messenger, don’t shoot the messenger… written by Galileo. Copyright Ellis Paul Music (SESAC) 2000. Reprinted with permission. All Galileo images copyright History of Science Collections, University of Oklahoma Libraries. Used with permission.

29 essay: verlyn klinkenborg

Bang. Moving further back in time—closer to the Big Bang—will mean bigger machines. At Fermilab, many people were looking almost wistfully over the horizon to 2007, when the Large Hadron Collider outside Geneva comes on line. That is where the coming generation of ground- breaking experiments will take place. The planning for the next particle accelerator after the Large Hadron Collider—the International Linear Collider, some 20 miles long—has already begun, and there is serious debate about where to build it. Recently, a National Research Council panel recommended that the United States should make a determined effort to build the International Linear Collider in this country as part of an international consortium. There’s no globalization like the globalization of science. A single major experiment at Fermilab

Photo courtesy of Verlyn Klinkenborg Photo courtesy of Verlyn often involves dozens, if not hundreds, of physicists and technicians from all over the world. The same will be true at the Large Hadron Collider, which is run by a 20-nation coalition. The research Renewing America’s in Illinois has shaped the research planned for Commitment to Switzerland, and those experiments will in turn shape the experiments planned for the High-Energy Physics International Linear Collider. But that doesn’t In October 2003, I gave an evening talk at the mean there aren’t significant advantages to Fermi National Accelerator Laboratory in Batavia, being the project’s host. If it isn’t built here, Illinois. The subject was nature on the familiar American scientists will go wherever it is built scale, the kind embodied in the restored prairie to do their research. The overwhelming risk, the on the Fermilab campus—some 1200 acres of panel concluded, is that without this project, compass plant and rattlesnake master and other the thrust of high-energy physics in this country species. But it’s impossible to visit a place like will simply die away. Fermilab without thinking about nature on This country desperately needs to recommit another dimension, the subatomic one being itself to basic research. In the 21st century, studied in the Tevatron collider, which looks from a particle collider 20 miles long happens to be the sky like an enormous, moated ring. one version of what basic research looks like. In the Tevatron, subatomic particles are accel- High-energy physics is hard to explain to the erated to extremely high speeds and crashed public. It cannot be justified in simple, pragmatic into each other within a detector chamber. That payoffs for American consumers, or simple, afternoon, I clambered through the scaffolding pragmatic payoffs for politicians. around the detector chamber as scientists tried But the justification is simple. Do we continue to explain to me what it all meant. To me it looked to ask fundamental questions about the universe like an incomprehensible array of electronics we live in, or do we not? To me, there is only one several stories high. The detector’s purpose is answer. The very soul of who we are as a spe- to capture a computerized image of the debris of cies, at our very best, is expressed in our undying each antiproton-proton collision. The particles curiosity. And in many ways, the very best of that emerge—varieties of quarks and mesons, who we are as Americans was expressed in the for instance—seem at first to have nothing to do commitment we made to basic research in the with nature as we know it on the human scale. 20th century. That commitment needs renewing.

Except, of course, that they have everything symmetry | volume 03 issue 05 june/july 06 Verlyn Klinkenborg to do with how the universe itself was formed. There is a basic rule about colliders. The Verlyn Klinkenborg writes The Editorial Observer column in The smaller or more evanescent the particle you are New York Times. This column originally ran on May 18, 2006. trying to observe, the more energy it takes. Copyright 2006, The New York Times Company. Reprinted with permission. Studying particle collisions at ever higher and higher energies is the only way to directly investigate the conditions that prevailed during the earliest microfractions of a second after the Big

30 logbook: ﬁrst vertex detector

collider at the Stanford Linear The Positron Electron Project (PEP)Accelerator Center produced its first collisions in 1979. All sorts of particles burst out, including the tau lepton, an ephemeral cousin of the electron. Theory had predicted the tau’s lifetime, but no one could measure it. John Jaros and his collaborators took on the challenge. “We built a precision drift chamber—the first collider vertex detector,” he says. The device had to pinpoint two vertices: a tau’s point of creation and its point of decay. Jaros’s team installed the new precision instrument at the center of the Mark II detector in 1981. That September, postdoc Nigel Lockyer overcame the intricacies of the Mark II software and, for the first time, transferred signals from the vertex detector to Mark II’s data acquisition system. This logbook shows his success—a cosmic muon traversing the entire Mark II detector—and notes “Nigel wins in overtime.” The vertex chamber (solid circle) had recorded with unprecedented precision the muon’s path (small crosses). The Mark II collaboration went on to map tau vertices and found the tau to wink into and out of existence over a scant 0.6 millimeters—long enough to scrutinize. By the following summer, the team reported a tau lifetime of about one third of a millionth of a millionth second, or 0.3x10-12 sec. Later, the collaboration used the chamber in one of the first lifetime measurements of the B meson, a composite short-lived particle containing a bottom quark. Today, vertex detectors—now using silicon technology—are the centerpieces of high-energy collider experiments around the world. Krista Zala Image courtesy of Mark II collaboration explain it in 60 seconds

What is elementary has demonstrated that the everyday Physics phenomena we experience are particle physics? governed by universal principles applying at time and distance scales far beyond normal human experience. Elementary particle physics is one avenue of scientiﬁc inquiry into these principles. What rules govern energy, matter, space, and time at the most elementary levels? How are phenomena at the smallest and largest scales of time and distance connected? To address these questions, particle physicists seek to isolate, create, and identify elementary interactions of the most basic constituents of the universe. One approach is to create a beam of elementary particles in an accelerator and to study the behavior of those particles—for instance, when they impinge upon a piece of material or when they collide with another beam of particles. Other experiments exploit naturally occurring particles, including those created in the sun or resulting from cosmic rays striking the earth’s atmosphere. Some experiments involve studying ordinary materials in large quantities to discern rare phenomena or search for as-yet-unseen phenomena. All of these experiments rely on sophisticated detectors that employ a range of advanced technologies to measure and record particle properties. Particle physicists also use results from ground- and space-based telescopes to study the elementary particles and the forces that govern their interactions. This latter category of experiments highlights the increasing importance of the intersection of particle physics, astronomy, astrophysics, and cosmology.

From Revealing the Hidden Nature of Space and Time: Charting the Course for Elementary Particle Physics (2006), Committee on Elementary Particle Physics in the 21st Century, National Research Council.

Symmetry A joint Fermilab/SLAC publication PO Box 500 MS 206 Batavia Illinois 60510 symmetryUSA

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