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SLAC BEAM LINEIn science there's nothing more tragic than theslaying of a beautiful theory by an ugly fact.

Thomas Huxley

Volume 19. Number 2 April 1989

The First Z° Particle Appears at the SLC

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2 SLAC Beam Line, April 1989

With this issue the Beam Line grows to a full 20pages, due mainly to a new feature that will appearregularly -a compendium of the scientific publica-tions issued by SLAC during the previous quarter.These comprise one of the principal end products ofthe lab's efforts, and the Directors have asked thatthey be listed herein.

They have also instituted an Editorial AdvisoryBoard for the Beam Line, whose purpose is to over-see its editorial direction and help suggest authorsand topics to be covered in these pages. The firstBoard includes John Matthews of Johns Hopkins,Associate Director John Rees and Marvin Weinsteinof the SLAC Theory Group. They are interested inhearing your opinions and suggestions.

Once again, our sincerest thanks to the hard-working individuals in the Publications Departmentwho helped us put this issue together. In partic-ular, Terry Anderson provided excellent drawings,Shirley Boozer gave invaluable aid with the typeset-ting, and Sylvia MacBride did precision paste-up ofthe camera-ready copy from which it was printed.Bette Reed and Crystal Tilghman handled relationswith photo services and printers. We could not havedone it without their efforts.

-the Editors

FROM THE DIRECTOR'S OFFICEAs you all know, we celebrated the production and

detection of the first Z° particle at the Stanford Lin-ear Collider (SLC) with an all-hands get-together onFriday afternoon, April 14. As I write this brief noteon the following Monday, the count of Z°'s recordedby the Mark II collaboration is up to four, with threemore having been produced over the past weekend.The SLC ran well thoughout the weekend, and thereis a pretty good chance that we already have anotherone or two more in the bag, waiting to be uncoveredby computer analysis of the data tapes.

All of this is of course very good news, but it isimportant to remember that the SLC is still a longway from reaching the performance levels for whichit was designed. Its ultimate success depends notonly on our ability to keep it operating efficiently andwith good beam characteristics in the days, weeksand months ahead, but also on our ability to makemajor improvements in its reliability and in the rateat which Z°'s are produced.

We have already learned a great deal about thisnovel collider, and the prospects for better opera-tion in the future are bright. As a small token ofour appreciation for all the hard work of the SLACstaff, which was crucial to the success of the SLC, theDirectors are enclosing with this issue of the BeamLine a color print of the first Z° to be produced atthis collider. Thank you all for your untiring effortsthis past year.

Burton Richter

Note added in proof: As this issue of the BeamLine went to press (May 10), the count of Z0's pro-duced by the SLC and observed by members of theMark II collaboration is over ten. During the dayshift on Monday, May 8, the SLC energy was loweredslightly in order to begin mapping out the shape ofthe Z°-production curve. Thus we are now well intothe process of getting important research informa-tion from the data on Z° production and decay.

The linear collider continues to work well, oftenoperating in a colliding-beam mode for better than50 percent of the time. We will soon begin takingsome steps that will increase the rate at which Z°'sare being produced. Let's keep up the good work.

BR

SLAC BEAM LINEMail Bin 80, (415) 926-2282Bitnet Address: BEAMLINE @ SLACVM

Editor: Michael RiordanAssistant Editors: Nina Adelman Stolar, Bill KirkEditorial Advisory Board:

John Matthews, John Rees, Marvin WeinsteinPhotography: Joe Faust, Tom NakashimaGraphic Arts: Walter ZawojskiProduction: Publications Department

IN THIS ISSUE:

From the Director's Office ........ 2The SLC Makes Its First Z° Particle . . . 3Still at It After 25 Years . . ...... 6SSRL Makes Advance in Angiography ... 7SLD Drift Chamber Stringing Finished .. 9Linear Collider Workshop ........ 10Internal Target Conference ........ 12The PEGASYS Proposal. ........ 12March SL UO Meeting .......... 13Dates to Remember .. . ...... 14Recent SLAC Publications .. ... . 14SLAC People in the News ........ 19Doug Dupen Heads Back to Campus . . . 20

Stanford University operates SLAC undercontract with the U.S. Department of Energy.

COVER PHOTO: Computer-generated image ofthe first Z° particle created at the SLC. It wasproduced at the center and decayed immediatelyto a pair of quarks, which converted into two back-to-back 'jets" of hadrons that left the tracks re-constructed here. (Photo by Joe Faust)

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THE SLC MAKES ITS FIRST Z° PARTICLESby Michael Riordan

The long wait is over. On April 11 the StanfordLinear Collider created its first Z° particle. Thearduous commissioning of this novel collider, whichbegan little more than two frustrating years ago, isfinally complete. SLAC again has a machine to doforefront research at the energy frontier. High-energyphysics has begun on the SLC.

Like the machine itself, the first Z° to be recordedat the SLC did not come without a struggle. It wascreated when an electron and positron annihilatedeach other at 7:32 a.m. on Tuesday, April 11. Thisfirst Z° disintegrated in a fraction of an eyeblink intoa pair of heavy quarks, which in turn converted al-most immediately into two back-to-back jets of sub-atomic particles that left telltale traces in the sur-rounding Mark II detector. One jet tore into thenorth endcap of the Mark II and the other slammedinto the south.

Fortunately the detector triggered on this event,which however slipped past the on-line computeranalysis. Its only remains, an innocuous string ofones and zeroes, was unceremoniously deposited onmagnetic tape for later off-line analysis. But the

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wrong tape number was entered into the Mark IIrunlog by weary physicists just ending the owl shiftthat morning, so the tape went unanalyzed - andthe event unrecognized -for almost another day.

At about 7:30 the next morning, April 12, Caltechpostdoc Barrett Milliken noticed that this tape hadjust been analyzed only a few hours earlier. He isone of a group of Mark II physicists calling them-selves the "fire-eaters" who had been poring throughthe data in search of the first Z°. Eagerly he beganrunning a program on the SLAC IBM 3090 computerthat enabled him to scan this recent data remotelyfrom his Caltech office.

His program identified two potential Z° candidateson tape number SC8725, but that was nothing out ofthe ordinary. "There were usually two or three suchcandidates on every tape," he said later, but a closerlook had always shown them to be "junk." This wastrue of the first candidate, too, but when Millikenbrought up the computer-reconstructed image of thesecond, he knew almost immediately that it was dif-ferent. The backgrounds in the detector were low,there was lots of momentum in charged particles, and

Muon System

Liquid ArgonCalorimeter

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Cut-away view of the Marak II detector, with the endcap removedand central drift chamber shifted left along the beam axis.

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Side view of the first Z° created at the SLC.

plenty of energy in the endcap calorimeters. "OnceI saw there was at least 25 GeV in the endcaps,"Milliken admitted later that day, "I knew it had tobe a real event."

But was it in fact a Z°? There are other kinds ofevents that can mimic it. Milliken began bringingup more images that showed the same event fromdifferent perspectives. He could discern one clear jetof four hadrons emerging toward the bottom and ahigh-energy track headed in the opposite direction,hitting the south endcap near a big energy deposit.There seemed to be two back-to-back jets of hadrons!

Just then Chris Hawkes, another Caltech fire-eater, strolled into the office and Milliken, excited,showed him the computer images of the event."Yeah," Chris agreed. "That's a Z°!"

Milliken put in a call to Jonathan Dorfan, headof SLAC Group C and a spokesman of the MarkII collaboration. Finding him at the Main ControlCenter (MCC) just before eight, he told Dorfan thathe thought they had a Z° and wanted him to take alook at it. Jonathan asked him to print off the imageson the MCC laser printer as soon as possible. Thenhe went into the MCC Conference Room to attendthe daily 8 o'clock meeting of physicists, engineersand technicians who for more than two years havebeen struggling to bring the SLC to life.

At this meeting there was plenty of head-scratching and hand-wringing going on. The previ-ous week outdoor air temperatures had hit a record95°F, and daytime brownouts had shut down theSLC, bringing back haunting memories of the pre-vious summer. But on Sunday evening, cool Pa-cific fogs once again began creeping over the Santa

Cruz Mountains, carrying with them ocean-like tem-peratures and ideal conditions for running the col-lider. The past few days the Mark II physicists hadbeen able to log data better than 25 percent of thetime. They were witnessing plenty of Bhabha scat-tering -glancing collisions between an electron anda positron. But no Z0 's had appeared yet. Not asingle one.

It was beginning to be a major quandary. Wherewere the Z°'s? Was 92 GeV the wrong energy atwhich to be searching for them? Already the MarkII had recorded 2.2 "Z-equivalents" worth of data, orenough total luminosity to have produced 2.2 Z°'s,had they been sitting right on the center of the Z°peak. And still none had appeared.

"When the number gets up to three Z-equivalents,the argument will begin among the Mark II collabo-ration that it's time to change energy," observed BurtRichter at meeting's end. "When it gets to five, therebels will win out!"

"Yeah," added Dick Taylor sitting next to him,"And then there'll be an argument about whether togo up or down!"

Dorfan had kept silent the entire meeting. Hewanted to see those images before saying anythingto anybody. They arrived about 8:15, shortly afterthe meeting ended. He picked them up and lookedat them intently. The view along the beamline wasnot entirely convincing, Dorfan recalled, but whenhe saw the side view, he was pretty sure they hadthe first Z° at last.

He called over Gary Feldman, head of SLACGroup H and another Mark II spokesman, to showhim the pictures. Then they both took Richter, whohad been standing nearby, into their confidence. Allthree agreed it was a strong Z° candidate, but de-cided not to broadcast the news until the collabora-tion could meet later that day to decide the mattercollectively.

But this was the kind of news that simply couldnot be suppressed. After more than a year of unan-ticipated technical problems that had delayed theSLC startup, the long Z°-drought was finally over.By mid-morning the SLAC corridors were hummingwith rumors of the great event.

Computer messages were flashing across oceansand continents, spreading the word far and wide tothe rest of the high-energy physics community. At10 o'clock, Richter received a BITNET message fromMario Greco in Rome, congratulating him on his suc-cess. Another came in just before noon from CERNDirector Carlo Rubbia, who had shared the 1984 No-bel Prize for discovering the Z° in 1983. "Congratu-lations," it read. "And welcome to the club."

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By the time the Mark II collaboration met earlythat afternoon in the SLAC Auditorium, the iden-tity of the event was a foregone conclusion. "I don'tthink there's anybody here who's seen this event anddoesn't think it's a Z°," said Dorfan, opening themeeting. Having flown up from Pasadena that morn-ing, Milliken presented his images next and explainedwhy it had to be a Z°. John Bartelt, a postdoc inGroup H, showed results of further analysis in whichhe relaxed certain cuts on the data. Two or threemore tracks became visible, reinforcing the interpre-tation of two back-to-back jets. "I haven't seen thismany smiling faces in a long time," observed Dorfanas the meeting ended with little doubt remaining inanybody's mind.

Corks popped and champagne flowed among theredwoods of the Panofsky Grove beginning at 4:00that afternoon, just as a press release went out fromStanford News Service letting all the world knowwhat had happened at SLAC. Richter took the op-portunity to clamber up onto a picnic table and ad-dress the couple hundred people who had gathered tocelebrate. "The significance of the event is not thatit represents a revolution in science," he cautioned."It's that the machine we struggled so hard to makework is starting to perform as it's supposed to."

By 6 o'clock TV crews were converging on SLAC tocover the day's events for the evening news. AndrewHutton, an accelerator physicist who heads the BeamDelivery group, had rushed home to change into coatand tie. (An hour earlier he was wearing sneakersand a T-shirt with a big green and yellow blob onit labeled "SUMO" in large red letters.) He handledthe interviews with graciousness and aplomb, even

Burton Richter congratulating SLAC staff in thePanofsky Grove (Photo by Edward Souza).

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Computer-reconstructed image of the fifth Z°produced at the SLC, showing three hadron jets.

though Channel 4's Sylvia Chase introduced him as"Dr. Burton Richter, Director of SLAC."

"A Triumph for Stanford's Huge Collider," crowedthe page-one headline on Thursday morning's SanFrancisco Chronicle. "Stanford's 2-Year StruggleYields an Elusive Z Particle," read the San Jose Mer-cury News. SLAC could finally bask in favorablepress coverage again.

At the 8 o'clock meeting that morning, Richtercongratulated everybody who had labored so longand hard to make the SLC work, but urged them notto let up. "One leaf," he quipped, "does not make alaurel wreath." He became increasingly fond of thissound bite as the day wore on and other TV crewsvisited SLAC to cover the previous day's excitement-the most we've had in a decade.

It felt as if a great weight had been lifted fromour shoulders and we could begin to breathe freelyagain. Only six months earlier, the SLC had beenshut down for repairs after a disappointing summerin which only 30 hours worth of data had been loggedand not a single Z° produced.

The fall and winter SLC upgrades have certainlymade a big difference, however, because the Mark IIhas been able to collect data about 30 percent of thetime lately - a vast improvement over last summer'sdiscouraging performance. That, and a doubling ofthe current in both electron and positron beams, arethe primary reasons the SLC can now produce Z°sat the rate of about one or two per day, as it provedthe weekend after making its first. Four more Z°swere recorded in less than three days' running.

While still not a wreath, there were five leaves inthe headband by week's end, an encouraging startfor the first linear collider ever built.

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STILL AT IT AFTER 25 YEARS

One of the original reasons for building SLAC andthe spectrometers in End Station A (ESA) was tomeasure the fundamental properties of what werethen considered elementary particles -the pro-ton and the neutron. Among these properties aretheir charge and magnetization currents, or how thesources of electric and magnetic fields are distributedwithin these particles. Never quite completed, theseimportant studies were taken up again early this yearin yet another ESA experiment, labelled NE-11.

One way to determine these two currents is to mea-sure the chances that an electron will scatter elasti-cally (i.e., bounce off the proton or neutron, leavingit intact) as a function of a single kinematic vari-able, generally chosen to be the momentum trans-ferred from the incident electron to the target parti-cle, or Q2. If the electron scatters at large or back-ward angles, the cross section or scattering probabil-ity is proportional to the magnetic form factor GMof the particle. At forward angles the cross section

depends on both GM and its electric form factor GE,which is related to its charge distribution. By makingmeasurements at forward and backward angles, bothform factors can be determined simultaneously (inwhat is called a Rosenbluth separation). To makean accurate determination of GE, however, requiresvery precise measurements of the elastic cross sectionover a wide range of scattering angles.

The task of measuring the proton and neutronform factors with high precision was recently takenup by a collaboration of nuclear and particle physi-cists using the ESA spectrometers. Led by Amer-ican University, the NE-11 collaboration includesphysicists from Lawrence Livermore Laboratory, theNational Bureau of Standards, Stanford Univer-sity, SLAG, and the Universities of Maryland, Mas-sachusetts, Pennsylvania and Rochester.

Over the years, many improvements have beenmade to the detectors in the 8 and 1.6 GeV spec-trometers in ESA to increase their reliability and re-producibility. A recent floating-wire measurement ofthe 8 GeV spectrometer led to a much better under-standing of its optical properties. These and other

t'he End Station A spectrometers. 'he 1.6 GeV spectrometer stands at left,behind the ESA pivot, and the 8 GeV spectrometer sits at right-center.

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improvements now allow cross sections to be mea-sured with relative systematic errors at or below the1 percent level.

For the NE-11 experiment, electron beams withenergies of 1.5 to 10 GeV were produced using theNuclear Physics Injector (NPI) and directed onto liq-uid hydrogen and deuterium targets in ESA. Elec-trons scattering at forward angles were detected inthe 8 GeV spectrometer, while those rebounding atlarge angles (greater than 60 degrees) were simulta-neously collected in the 1.6 GeV spectrometer. Thelatter device had been modified to increase its solidangle (and hence data collection rate) by a factor offive.

Beam was delivered a remarkable 50 percent ofthe time during a six-week running period in Januaryand February. A record for the peak current intensity(6.5 x 1011 electrons per beam pulse) was set, prin-cipally because the new 6045 klystrons produced forthe SLC had finally been installed throughout linacsectors 25 through 30 (those used to accelerate NPIbeams). The highest energy used, 10 GeV (runningin the SLED mode), was also an NPI record. Andbeam stability was much enhanced due to the manyimprovements made for the SLC.

From the measured elastic e -p cross sections, theproton form factors were separately determined up toQ2 = 7 (GeV/c) 2. Neutron cross sections were mea-sured up to 4 (GeV/c) 2 by scattering electrons from adeuterium target and subtracting contributions fromelastic e - p scattering. In both cases, NE-11 haseffectively doubled the Q2 range over which Rosen-bluth separations of the nucleon form factors havebeen performed. The full results of this experimentshould be published within a year.

Peter Bosted

SSRL MAKES MAJORADVANCE IN ANGIOGRAPHY

On March 15 a team of physicians and scientistsfrom Stanford University, Lawrence Berkeley Labo-ratory and Brookhaven National Laboratory made amajor advance in the imaging of human coronary ar-teries. Led by Edward Rubenstein of Stanford Medi-cal School, they employed dual beams of synchrotronradiation produced in a dedicated run on the SPEARstorage ring. Sharp, high-quality images were ob-tained by a noninvasive process imposing much lessrisk on patients than methods commonly use in hos-pitals today.

At the present time, the diagnosis of coronary ar-terial diseases requires a risky angiographic proce-dure in which a peripheral artery is punctured anda catheter is carefully threaded back to the heart it-self. The tip of the catheter is then guided into theartery to be examined. Injection of a contrast agentcontaining iodine through the catheter permits thesuspect artery to be imaged using conventional X-raytechniques. Diagnostic-quality images result, but atconsiderable risk to the patient. The catheter cancause a heart attack or stroke, or it can trigger car-diac arrhythmias. About five patients in a thousandsuffer some ill effects from the exam, and about onein a thousand dies as a result of it.

Human angiogram made by the new method de-veloped at SSRL. The dark areas are the aortaand ventricles; the rings at upper left are su-tures remaining in the patient from previousheart surgery (SSRL photo).

Segre Dead at 84We regret to hear about the passing of Emilio

Segre Emeritus Professor of Physics at the Uni-versity of California, Berkeley. He died of a heartattack while walking near his home in Lafayette,California, on Saturday, April 22.

Segre earned his Ph.D. in physics at the Uni-versity of Rome, working on nuclear physics underthe tutelage of Enrico Fermi. While a professor ofphysics at Berkeley, he teamed with Owen Cham-berlain to discover the antiproton on the Bevatronparticle accelerator, for which the two men wereawarded the 1959 Nobel Prize in physics.

Segre authored many books, among them Nu-clei and Particles, a textbook, and From X-rays toQuarks, a history of nuclear and particle physics.His broad-ranging talents will indeed be missed.

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Artist's conception of angiography procedure developed at SSRL. Two beams of X-raysare passed through the patient's heart simultaneously and their images recorded by twoseparate detectors. By subtracting one image from the other, the effects of soft tissuesand bone can be eliminated, enhancing the contrast.

A safer procedure called intravenous angiographyentails placing the catheter into a major vein ratherthan an artery. In this approach there is no riskof heart attack, stroke or arrhythmia. But the con-trast agent is diluted by the blood before reachingthe coronary arteries, which consequently cannot beimaged using conventional X-ray techniques.

The high-intensity, monochromatic X-ray beamsavailable at the Stanford Synchrotron RadiationLaboratory (SSRL) have allowed researchers to en-hance the image contrast markedly, thereby permit-ting use of the intravenous approach. By using twobeams simultaneously, one with an energy just belowthe K-edge of iodine (33.16 keV) and the other justabove it, they can make the coronary arteries standout distinctly. Because the absorption of one beamby iodine is six times greater than the other whilethere is little change for soft tissue and bone, thedifference between the images made with each beamwill reveal contrast only from the iodine and not thesurrounding tissues.

The imaging apparatus used in the March run wasmuch improved over that used in previous (1986-87)SSRL tests on human patients. The recent exper-iments were performed on beamline 4-2, which is

illuminated by an 8-pole, 18 kG wiggler magnet (seeJanuary 1989 Beamline, p. 3, for a discussion of wig-glers). The 3 mm high by 12 cm wide beam of 33 keVsynchrotron radiation strikes two separate diffract-ing crystals, which produce the two X-ray beams (ofslightly different energy) simultaneously. The twobeams converge into a single horizontal line at thepatient's heart and then diverge toward two arrays ofposition-sensitive detectors. As the patient is movedvertically through the beams in a specially designedchair, two separate images are recorded electroni-cally, and a full two-dimensional image of the bloodcirculation is obtained by logarithmic subtraction.The total X-ray dosage absorbed by the patient isfar less than the typical dosage in hospital-based an-giograms today.

The image quality obtained in the 1989 experi-ment was significantly better than that obtained inprevious tests. Although preliminary results are veryencouraging, however, final judgment must await adetailed analysis of the twenty-odd images obtained.The angiography group owes a debt of gratitude tothe many people at SSRL and SLAC who contributedto the success of this experiment.

George Brown

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Connie Reeve prepares a bundle of sense wiresand guard wires for testing and installation.

SLD DRIFT CHAMBERSTRINGING IS FINISHED

The stringing of the SLD central drift chamber(CDC) was completed early in April, a little morethan six months after it had begun. Filled with gas(mostly argon and carbon dioxide), this cylindricalchamber will eventually sit at the core of the SLD,detecting the passage of charged particles, which ion-ize the gas molecules. The ions drift to "sense wires"under the influence of electric fields set up by "fieldwires" running parallel to the chamber axis. Thepattern of particle tracks thus deposited on the sensewires is reconstructed by computer, providing a vi-sual image of an e+e - collision.

There are ten layers of wires in the CDC, groupedinto 640 cells. Each cell contains 25 field wires plus8 sense wires surrounded by an array of 20 "guardwires." Every one of this total of more than 30,000wires had to be painstakingly strung and then putthrough a series of rigorous tests before being in-serted into the chamber through precision-drilledholes in the aluminum end plates. In an averageweek 30 cells were strung, tested, and installed inthe chamber.

There is still plenty of work remaining to be done,however, before the CDC becomes a useful, func-tioning particle detector. Gas manifolds and cooling

After a rigorous series of tests, the bundles ofwires are individually inserted through the endplates of the cylindrical drift chamber.

loops must be installed; high-voltage distributionand signal-processing circuitry will be added. Oncethese tasks are finished this fall, the detector willbe moved from its clean room in the Light Fabrica-tion Building and installed inside the SLD magnetyoke (see January 1989 Beam Line). Commissioningshould begin by the end of 1989.

_ Michael Riordan

Interior view of the SLD drift chamber.

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LINEAR COLLIDER WORKSHOPThe International Workshop on Next-Generation

Linear Colliders was held at SLAC between Novem-ber 28 and December 9, 1988. There were 113participants including 28 from outside the UnitedStates representing Novosibirsk in the USSR; CERN,DESY, Frascati and Orsay in Europe; and KEK inJapan. Such broad participation indicates the world-wide interest in linear colliders. The purpose of theworkshop was to discuss the research programs onlinear colliders around the world, to identify areasthat are common or complementary in their goalsand to advance these programs by collaboration.

Plenary sessions were held the first two and onehalf days in the auditorium, where representativesfrom various laboratories and institutions presentedtheir latest linear collider designs and research pro-grams. For most of the next week, the partici-pants formed seven working groups to discuss in moredetail specific programs on individual subsystems.During this period, there was a lively exchange ofideas within and between the groups. Their resultswere summarized and presented in two days of ple-nary sessions at the end of the meeting.

The Parameters working group examined the ex-isting designs for high-energy linear colliders, whichsport the acronyms CLIC, ILC, JLC, TLC andVLEPP, and tabulated their design parameters ina consistent form to aid comparisons. Another group

John Rees and Perry Wilson, Co-Chairmen ofthe Parameters working group.

working on Beam Dynamics and Wakefields stud-ied emittance preservation (i.e., keeping the electronbunches compact and focused) from damping ringsthrough to the final focus and the problems associ-ated with the use of multibunch trains of particles.The group of specialists studying Damping Ringsand Sources concluded that the desired emittancescould be achieved in several different designs, all ofwhich require wiggler magnets in the rings.

One of the largest working groups concentratedon the topic of RF sources. This key problem re-quires a continuing worldwide effort to explore al-ternate and complementary solutions. The researchprograms discussed included many "small" sourcesof "modest" power, sources with peak power outputsof more than a gigawatt, and two-beam acceleratorswhere energy of the drive beam ranged from tens ofMeV to several GeV. This RF power is needed to

Workshop Chairman Ewan Paterson (left) talks energize novel Accelerator Structures, a topic whichwith Witold Kozanecki and John Seeman dur- had its own working group that discussed new con-ing one of the coffee breaks between sessions. struction techniques, experiments on RF breakdown

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SLAC Beam Line, April 1989 11

SLAC's Andrew Hutton (right) sampling wineswith noted French oenophiles Joel LeDuff (left)and Michel Davier of LAL-Orsay.

limits, and designs that damp out wakefields to allowmultibunch operation.

The working group on Instrumentation exploredthe precision and tolerances needed in various de-signs of damping rings and accelerators. Many tech-niques for component alignment and beam diagnos-tic measurements were explored, but considerableresearch is clearly required to achieve the desiredperformance level. One problem identified is theextreme difficulty in collimating high-power, low-emittance beams.

A large working group studied problems associatedwith the design of the Final Focus. Participants dis-cussed the geometry around the collision point us-ing different crossing angles and "crab" crossing toprovide head-on collisions. The biggest surprise of

the particles radiate in the electromagnetic fieldsbunch populations, these "beamstrahlung" photonscan generate electron-positron pairs by interactionswith the opposing beam. Subsequently deflected tolarge angles, these pairs can cause severe backgroundproblems for the detector surrounding the interac-tion point. The whole subject of beamstrahlung pairproduction and deflection will need much more studybefore collider and final focus parameters can ever beoptimized.

A proposed Final Focus Test Beam at SLAC, usingthe SLC beam as input, was well received and muchdiscussed. Many groups expressed interest in collab-oration on both construction and use of this beam-line. Its unique capabilities will make it an importantpart of a linear collider R&D program where opticsideas, hardware and beam instrumentation can bedeveloped and tested. After the workshop there willbe continuing discussions on the organization of aninternational collaboration to construct and use thisfacility.

Overall, the workshop was a great success and con-tributed much to advancing our knowledge of futurelinear colliders. The excellent technical and socialinteractions which took place augur well for our con-tinuing collaboration.

-Ewan Paterson

(Editor's note: The Workshop Proceedings, consist-ing of the working-group summaries and copies ofthe transparencies of the final plenary-session talks,is available as SLAC Report No. 335.)

the workshop appeared in the general subject area Sergei Kazakov, Nilolay Solyak and Vasilliof beam-beam interaction effects. In the very strong Parkhomchuk (left to right) of Novosibirsk en-beam-beam interaction typical of linear colliders, of joying California wines with Samuel Heifets ofthe opposing bunch. Under conditions with high CEBAF. (All photos these pages by Elsi Stucki)


INTERNAL TARGET CONFERENCE

For the past few years an assortment of nuclear andparticle physicists from institutions such as Ameri-can University, Lawrence Livermore Laboratory andthe University of Massachusetts have been consid-ering a novel idea. They want to use the PEPstorage ring for fixed-target experiments. Whatmakes this sleight of hand feasible is the use ofa gas-jet target, which shoots a narrow stream ofatoms (hydrogen, helium, argon, xenon, for example)through the circulating electron beam. Pioneered atCERN and Novosibirsk, such "internal target" facil-ities will allow physicists to study electron-nucleonand electron-nucleus collisions in far more detail thanhas been previously possible.

From January 9 through 12, about a hundredphysicists from around the world met in the SLACAuditorium to discuss the prospects for and prob-lems of experiments in this growing field. The Top-ical Conference on Electronuclear Physics with In-ternal Targets drew large contingents from CERNand MIT; Caltech, Fermilab, Frascati, Livermore andNovosibirsk were also well represented. The Con-ference was organized and chaired by Ray Arnoldof American University, Coordinator of the NuclearPhysics at SLAC (NPAS) program; he was ably as-sisted by Lynn Hanlon and Elsi Stucki.

The opening session was devoted to a discussion ofthe physics accessible at electron storage rings withinternal targets. Stan Brodsky noted that electro-production experiments continue to be the definitiveway to resolve the structure of nucleons in terms oftheir constituent quarks and gluons. Recent surpris-ing revelations by the EMC collaboration at CERN,reviewed by Frank Close of Tennessee, suggest thatthe proton spin might not be due merely to the spinof the quarks, as previously supposed. Some theo-rists have proposed that the gluons are responsible,while others point to orbital motion of the quarks.Whatever the case, electron scattering from polar-ized targets should help provide some answers. Theentire question of how quarks are organized withinnucleons is still remarkably unresolved; it will benefitfrom the detailed studies that can be performed atinternal target facilities.

Hadronization of the struck quark in deep inelas-tic scattering was another subject of strong inter-est. By studying the hadrons produced when lep-tons strike different nuclei, noted Andreas Bialas ofCracow, physicists can gain added insight into thispoorly understood process. So far most such experi-ments have been accomplished with beams of muonsand neutrinos at CERN and Fermilab. The excellentduty cycle and high luminosities available at electron

The PEGASYS Proposal

PEGASYS (for PEp GAs-jet SpectrometersYStem) is a joint nuclear/high-energy physicsfacility being proposed for the PEP storage ring.It consists of a multi-gas cold-cluster jet target,a forward dipole spectrometer (of approximatelyone steradian solid angle) with full particle-identification capability, and nuclear physics de-tectors surrounding the target to measure decaysof spectator fragments.

Operation of PEGASYS will be fully compat-ible with both colliding-beam physics and syn-chrotron radiation research, which can occur onPEP simultaneously. Luminosities of1033 cm-2s- 1

will be possible with hydrogen and deuteriumtargets and 1030 is achievable with xenon. Thethin, pointlike target, the time structure of thePEP beam, and the large-aperture spectrometershould open up a whole new realm of multipar-ticle coincidence measurements of deep-inelasticelectron scattering that are impossible to carryout in End Station A.

The research anticipated for PEGASYS in-cludes experiments where nuclei are used as a"laboratory" to study the space-time evolution ofstruck quarks in deep-inelastic scattering (quarkpropagation and hadronization) and studies offundamental QCD processes for nucleons (virtualCompton scattering and "higher-twist" effects).Measurements of structure functions tagged onspecific nuclear decays should help to understandthe origin of the EMC effect. Also plannedare measurements of the high-momentum quarkcontributions to the deuteron wavefunction andsearches for neutral bosons decaying into leptons.

Formed in 1986, the PEGASYS collaborationhas now grown to include groups from twentyuniversities and research laboratories. The NPASProgram Advisory Committee approved the pro-posal at its January meeting and called for aformal Technical Review to be held early thisfall. The Nuclear Science Advisory Committee(the parallel body to HEPAP) warmly receiveda presentation of the project in February. If itpasses further review and receives appropriatefunding, now estimated at about $10 million,PEGASYS could begin experimentation by late1992 or early 1993.

- arl Van Bibber

storage rings, however, make them the ideal place toexamine the hadronization process in great detail.

The circulating electron bunches in a storage ringprovide high average currents that appear almostcontinuous to a particle detector. Such a beam is far

.

13

better suited for detecting several secondary particlesin coincidence than are the beams with short pulsedurations extracted from electron accelerators likeSLAC. With a large-acceptance detector, it becomesfeasible to analyze most of the spray of particles andnuclear fragments produced in electron-nucleus col-lisions. Karl Van Bibber of Livermore described thePEGASYS internal target facility (see box) proposedfor the PEP storage ring. The PEGASYS collabora-tion aims to study both the fate of the struck quarkas it hadronizes and the response of a nucleus to thesudden removal of one of its quarks.

Another advantage of gas-jet targets is the factthat they are so thin that slow particles and heavynuclear fragments are not absorbed in the target andcan thus reach detectors. A whole new class of nu-clear structure measurements therefore becomes pos-sible in which heavy-fragment "tags" are used at low-energy storage rings. Stan Kowalski outlined the 1GeV electron stretcher ring and internal target facil-ity under construction at the MIT-Bates linear ac-celerator, and Kees de Jager revealed similar plansfor NIKHEF in Amsterdam.

A major potential bonus of gas-jet targets is thepossibility of producing targets of polarized nuclei.The recent EMC surprises in muon scattering frompolarized protons have whetted theorists' appetitesfor similar measurements on the neutron, which willrequire targets of polarized deuterium or helium-3.The polarized targets of solid materials used pre-viously in external beams have often proved un-wieldly, but beams of polarized atoms are beginningto show promise. Richard Milner of MIT discussedrecent work on a novel polarized target with opticallypumped helium-3 atoms and described plans for anexperiment being proposed for HERA to measure thespin structure functions of the nucleons.

Several other speakers described the wide range ofgroups planning to use internal targets in circulatingproton or anti-proton beams. Louis Dick reviewedthe UA6 experiment, which used a "cluster-jet" tar-get of hydrogen atoms in the CERN pp collider tostudy pp collisions. And Martin Perl indicated howthe PEGASYS facility might even be used to per-form bona fide searches for new particles - such asneutral spin-0 and spin-1 bosons weakly coupled toelectrons.

At week's end, conference participants departedwith a new appreciation of the great variety of ex-periments that will soon be possible with internaltargets. They also had a much better idea of thework remaining to be done before such facilities be-come commonplace features at storage rings aroundthe globe.

- Michael Riordan

MARCH SLUO MEETING

After an extended period of relative inactivity,the SLAC-LBL Users Organization (SLUO) met onMarch 4. About 40 representatives of SLAC and thevarious universities engaged in research here gath-ered in the Orange Room for day-long discussions ofhow SLUO might take a stronger role in meeting thefuture needs of the users and SLAC itself.

Serving as acting chairman, Uriel Nauenberg ofColorado opened the meeting by reviewing the his-tory of SLUO. He indicated his willingness to serveas the official Chairman of the organization, replac-ing Richard Prepost of Wisconsin whose term endedrecently, but felt that an election more in accord withthe SLUO charter should be held for all the offices.

Immediately following Nauenberg, Burton Richterpresided over a lengthy and broad-ranging discus-sion concerning the future of SLAC and the nationalhigh-energy physics program over the next five to tenyears. One of the central concerns voiced was how tomaintain an active and vital research program dur-ing a period in which national resources are being di-verted toward building the SSC. Since research thereis at least ten years away, it is of utmost importancethat SLAC chart a course that will continue to of-fer forefront research facilities in the interim -thenext five to eight years. There is growing interest atSLAC in a number of possible new projects at SLAC;B factories, tau/charm factories, and SSC detectordevelopment were mentioned.

Richter expressed the need for a strong and activeSLUO organization to help in addressing these futureneeds, and offered secretarial and financial supportto achieve this goal. He encouraged SLUO input andsuggested that the organization become involved inoffering workshops to discuss possible future projectsat SLAC.

There was discussion about the membership ofSLUO, now that SLAC facilities are also being usedby nuclear physicists and scientists working with syn-chrotron radiation. The general consensus was thatthe former be included in SLUO because their needsclosely resemble those of the high-energy physicscommunity. SSRL users, a very large communitywith relatively short-term experiments, had differentneeds and their own organization to meet them.

In response to a question about the SLC, Richterreviewed the recent upgrades and discussed the per-formance of the collider through early March. Hesaw a marked improvement over last summer's per-formance and suggested that high-energy physics re-search would soon begin.

. I


1 S

After considerable discussion about election pro-cedures, nominations were made and the followingSLUO officers elected:

Chairman: Uriel NauenbergSecretary/Treasurer: Richard Kofler

Coordinator of Committees: Bruce Barnett

These officers will serve until the fall of 1989, a termconsistent with the charter, unless new officers arerequired earlier by a possible reorganization.

There was a wide-ranging discussion about such areorganization of SLUO, whose charter was formu-lated in 1975 and needs to be reexamined. Amongother things, the relationship between SLAC andLBL has changed, and the charter should be up-dated accordingly. The discussion culminated withthe nomination of members to serve on a SLUO Re-organization Committee.

From this list of nominees the chairman selectedRay Arnold of American University, Alberto Ben-venuti of INFN Bologna, Elliott Bloom of SLAC,Donald Coyne of UC Santa Cruz, Gail Hansen ofIndiana University, Michael Ronan of LBL, AlanWeinstein of Caltech and Richard Yamamoto of MITto serve on the committee.

It was a good start, but much remains to be donebefore SLUO becomes a truly effective organization.The next general meeting is scheduled for Fridaymorning, June 2, in the SLAC Auditorium.

-Dick Kofler

Dates to Remember

Scientific PolicyCommittee Meeting

Tau-Charm Factory Workshop

Experimental ProgramAdvisory Committee Meeting

SLAC-LBL UsersOrganization Meeting ....

SLAC Summer Institute . . .

SLD CollaborationMeeting (Kirkwood) . . .

International Symposium onLepton-Photon Interactions

May 4-6

May 23-27

May 30-31

. . June 2

July 10-21

July 31-August 5

August 7-12

SSRL Users Conference .... October 19-20

RECENT SLAC PUBLICATIONS

The following is a list of SLAC publications is-sued during the first quarter of 1989, from January 1through March 31. They are organized according tofive categories: Experimental High-Energy Physics,Theoretical Physics, Accelerator Physics, Instrumen-tation and Techniques, and Other Topics. To obtaincopies of these publications, write to the PublicationsDepartment, SLAC Bin 68, P. O. Box 4349, Stanford,CA 94309, U.S.A. Please be sure to specify authorand publication number in your request.

Experimental High-Energy Physics

MARK-III Collaboration: J. Adler, et al., "Mea-surement of the Branching Fractions for Do ->7r-e+ve and D > - K-e+ve and Determination of(Vcd/Vcs) 2 ," (SLAC-PUB-4745, Jan 1989; Submittedto Phys. Rev. Lett.).

J. Alexander, et al., "Search Strategies for HiggsBosons at High-Energy e+e - Colliders," (SLAC-PUB-4775, Jan 1989; Contributed to DPF SummerStudy: Snowmass '88, High Energy Physics in the1990's, Snowmass, Colo., Jun 27 - Jul 15, 1988).

D. Aston, et al., "Recent Results in StrangeoniumSpectroscopy," (SLAC-PUB-4773-Rev., Feb 1989;Revised version. Invited talk given at 1988 AnnualMtg. of the Div. of Particles and Fields of the APS,Storrs, Conn., Aug 15-18, 1988).

D. Aston, et al., "Recent Results from S = -3 BaryonSpectroscopy from the LASS Spectrometer," (SLAC-PUB-4821, Feb 1989; Invited talk given at SummerInst. on Elementary Particle Physics, Stanford, Cal.,Jul 17-28, 1988).

W.B. Atwood, "B Meson Physics with PolarizedElectron Beams at Linear Colliders Running at theZ°," (SLAC-PUB-4827, Dec 1988; Presented at DPFSummer Study Snowmass '88, High Energy Physicsin the 1990's, Snowmass, Colo., Jun 27 - Jul 15,1988).

C. Baltay, et al., "New Particle Searches ine+e- Collisions," (SLAC-PUB-4844, Jan 1989; Pre-sented at DPF Summer Study: Snowmass '88, HighEnergy Physics in the 1990's, Snowmass, Colo., Jun27 - Jul 15, 1988).

MAC Collaboration: H.R. Band, et al., "A Mea-surement of the e+e- - BB Forward - BackwardCharge Asymmetry at s = 29 GeV," (SLAC-PUB-4871, Feb 1989; Submitted to Phys. Lett. B).

J. Dorfan, "Z° Physics at the SLC," (SLAC-PUB-4816B, Feb 1989; Lectures at Banff Summer Inst.,

.

14I



Aug 1988 and NATO ASI on Techniques and Con-cepts of High Energy Physics, St. Croix, V.I., Jul

14-25, 1988).

G.J. Feldman, et al., "Report of the B Factory

Group. 1. Physics and Techniques," (SLAC-PUB-4838, Jan 1989; Contributed to DPF Summer Study:

Snowmass '88, High Energy Physics in the 1990's,

Snowmass, Colo., Jun 27 - Jul 15, 1988).

W.T. Ford, et al., "Measurement of a, from Hadron

Jets in e+e- Annihilation at /s of 29 GeV," (SLAC-PUB-4348, Jan 1989; Submitted to Phys. Rev. D).

K.K. Gan, "Searching for an Exotic Lepton and

Gauge Boson at High-Energy e+e- Colliders,"

(SLAC-PUB-4748, Jan 1989; Contributed to DPF

Summer Study Snowmass '88: High Energy Physics

in the 1990's, Snowmass, Colo., Jun 27 - Jul 15, 1988,

Submitted to Phys. Rev. D).

P. Grosse-Wiesmann, "H° at a 300 GeV e+e- Collider,"

(SLAC-PUB-4616, Dec 1988; Presented at Workshop

on Intermediate Mass and Nonminimal Higgs Bosons

at the SSC, Davis, Cal., Jan 4-6, 1988).

C.A. Hawkins and Martin L. Perl, "An Explorationof the Limits on Charged Lepton Specific Forces,"

(SLAC-PUB-4721, Nov 1988; Submitted to Phys.

Rev.).

C.A. Hawkins, "Tests of QED to Fourth Order in

a in e+e- Collisions at 29 GeV," (SLAC-0337, Feb

1989; Ph.D. Thesis).

C. Hearty, et al., "Search for the Anomalous Pro-

duction of Single Photons in e+e- Annihilation at

s- = 29 GeV," (SLAC-PUB-4684-Rev., Mar 1989;

Submitted to Phys. Rev. D).

D. Hitlin and W. Toki, "Hadronic and Radiative De-

cays of the J/b," (SLAC-PUB-4853, 1988; Publishedin Ann.Rev.Nucl.Part.Sci. vol.38, pp.497-532, 1988).

S. Klein, et al., "A+ Production and Semileptonic

Decay in 29 GeV e+e- Annihilation," (SLAC-PUB-

4696, Feb 1989; Submitted to Phys. Rev. Lett.).

Sachio Komamiya, et al., "Searches for NonliminalHiggs Bosons from a Virtual Z Decaying Into a Muon

Pair at PEP," (SLAC-PUB-4771, Jan 1989; Submit-

ted to Phys. Rev. D).

MARK-III Collaboration: U. Mallik, "Results from

MARK-III on the J/1 Decays," (SLAC-PUB-4828,Jan 1989; Invited talk given at Mtg. of BNL Work-

shop on Glueballs, Hybrids and Exotic Hadrons, Up-

ton, N.Y., Aug 29 - Sep 1, 1988).

Martin L. Perl, "Tutorial Guide to the Tau Lepton

and Close Mass Lepton Pairs," (SLAC-PUB-4739,

Oct 1988; Invited talk given at Int. School of Sub-nuclear Physics, The Super World III, Erice, Italy,

Aug 7-15, 1988).

Martin L. Perl, "The Tau and Beyond: Future Re-

search on Heavy Leptons," (SLAC-PUB-4819, Jan

1988; Presented at 8th Int. Conf. on Physics in Col-

lision, Capri, Italy, Oct 19-21, 1988).

Martin L. Perl, "Tau Physics and Tau Factories,"

(SLAC-PUB-4855, Jan 1989; Presented at Rare De-

cay Symposium, Vancouver, Canada, Nov 30 - Dec

3, 1988).

MARK-III Collaboration: D. Pitman, "Evidence for

D+ -,e+X," (SLAC-PUB-4826, Jan 1989; Invited

talk given at 16th SLAC Summer Inst. on Ele-

mentary Particle Physics, Stanford, Cal., Jul 18-29,

1988).

N.A. Roe, "Resonance Production in Two Photon

Interactions," (SLAC-0338, Feb 1989; Ph.D. Thesis).

MARK-III Collaboration: R.H. Schindler, "Results

on Semileptonic DO and Ds Decays and Evidence for

Non DD Decays of the b(3770)," (SLAC-PUB-4694,Dec 1988; Invited talk given at 24th Int. Conf. on

High Energy Physics, Munich, West Germany, Aug

4-10, 1988).

MARK-III Collaboration: W. Toki, "Review of J/b

Decays," (SLAC-PUB-4784, Nov 1988; Invited talk

given at Mtg. of Div. of Particles and Fields of the

APS, Storrs, Conn., Aug 15-18, 1988).

W. Toki, "BNL Glueball Review," (SLAC-PUB-

4824, Dec 1988; Invited talk given at Mtg. on

BNL Workshop on Glueballs, Hybrids and Exotic

Hadrons, Upton, N.Y., Aug 29 - Sep 1, 1988).

E.M. Wang, et al., "Higgs - Four Leptons at the

SSC," (SLAC-PUB-4876, Feb 1989; Contributed to

DPF Summer Study: Snowmass '88, High Energy

Physics in the 1990's, Snowmass, Colo., Jun 27 - Jul

15, 1988).

Theoretical Physics

Changrim Ahn and Mark A. Walton, "Spectra of

Strings on Nonsimply Connected Group Manifolds,"

(SLAC-PUB-4870, Feb 1989).

Varouzhan Baluni, "Embedding and Breaking of

Gauge Symmetries," (SLAC-PUB-4825, Jan 1989;

Submitted to Phys. Lett.).

Geoffrey T. Bodwin, et al., "Effects of Initial State

QCD Interactions in the Drell-Yan Process," (SLAC-

PUB-4813, Dec 1988; Submitted to Phys. Rev. D).


Roger Brooks, "Topological Invariants and a GaugeTheory of the Superpoincare Algebra in Three Di-mensions," (SLAC-PUB-4799, Nov 1988; Submittedto Nucl. Phys. B).

Roger Brooks, "The Spectrum of Topological Quan-tum Field Theories on N Manifolds," (SLAC-PUB-4901, Feb 1989; Submitted to Nucl. Phys. B).

C.G. Callan and L. Thorlacius, "Using Reparametriza-tion Invariance to Define Vacuum Infinities in StringPath Integrals," (SLAC-PUB-4765, Oct 1988; Sub-mitted to Nucl. Phys. B).

Jong Bum Choi, "Annihilation Contributions in aWilson Loop Formalism," (SLAC-PUB-4842, Jan1989; Submitted to Phys. Rev. D).

Jong Bum Choi, "Linear Plus Coulomb Potential orT(6s)?" (SLAC-PUB-4854, Feb 1989; Submitted toPhys. Rev. D).

Savas Dimopoulos, et al., "Cross-Sections for Lep-ton and Baryon Number Violating Processes fromSupersymmetry at pp Colliders," (SLAC-PUB-4797,Sep 1988; Submitted to Phys. Rev. D).

Frederick J. Gilman, "Prospects in B Physics,"(SLAC-PUB-4829, Dec 1988; Invited talk given atRare Decay Symposium, Vancouver, Canada, Nov30 - Dec 3, 1988).

David Horn, et al., "Heisenberg Antiferromagnet ona Triangular Lattice," (SLAC-PUB-4880, Feb 1989;Submitted to Phys. Rev. D).

Kent Hornbostel, "The Application of Light ConeQuantization to Quantum Chromodynamics in(1+1) Dimensions," (SLAC-0333, Dec 1988; Ph.D.Thesis).

Yosef Nir, "The Mass Ratio mc/mb in SemileptonicB Decays," (SLAC-PUB-4847, Jan 1989; Submittedto Phys. Lett. B).

Yung Su Tsai, "Production of Neutral Bosons by anElectron Beam," (SLAC-PUB-4877, Mar 1989; Sub-mitted to Phys. Rev. D).

P. Voruganti, "Stable Static Solitons in the Nonlin-ear Sigma Model with a Topological Term," (SLAC-PUB-4807, Jan 1989).

Accelerator Physics

P. Bambade, et al., "Rollfix: an Adiabatic RollTransition for the SLC Arcs," (SLAC-PUB-4835,Jan 1989; Contributed to IEEE Particle AcceleratorConf., Chicago, Ill., Mar 20-23, 1989).

P. Bambade, et al., "Operational Experience withOptical Matching in the SLC Final Focus System,"(SLAC-PUB-4776, Jan 1989).

P. Bambade, et al., "Observation of Beam-Beam De-flections at the Interaction Point of the SLAC LinearCollider," (SLAC-PUB-4767, Jan 1989; Submittedto Phys. Rev. Lett.).

P. Bambade and A. Hutton, "Specification of Har-monic Corrections (Wirefix) for the SLC Arcs,"(SLAC-CN-370, February 1989).

Giovanni Bonvicini, et al., "First Observation ofBeamstrahlung," (SLAC-PUB-4856, Mar 1989; Sub-mitted to Phys. Rev. Lett.).

Pisin Chen, et al., "A Bootstrap Disruption SchemeUsing a Final Focus Under a Dense Plasma Lens,"(SLAC-PUB-4746, Oct 1988; Submitted to Phys.Rev. Lett.).

Pisin Chen, "Review of Linear Collider Beam-Beam Interaction," (SLAC-PUB-4823, Jan 1989;Contributed to U.S. Particle Accelerator School,Batavia, Ill., Jul 20 - Aug 14, 1987).

Pisin Chen, "Disruption, Beamstrahlung and Beam-strahlung Pair Creation," (SLAC-PUB-4822, Dec1988; Contributed to DPF Summer Study Snowmass'88, High Energy Physics in the 1990's, Snowmass,Colo., Jun 27 - Jul 15, 1988).

P. Emma, et al., "Online Monitoring of Disper-sion Functions and Transfer Matrices at the SLC,"(SLAC-PUB-4907, Mar 1989; Presented at IEEEParticle Accelerator Conf., Chicago, Ill., Mar 20-23,1989).

W.T. Ford, et al., "Interactive Beam Tuning Simu-lator for the SLC Final Focus," (SLAC-PUB-4915,Mar 1989; Contributed to IEEE Particle AcceleratorConf., Chicago, Ill., Mar 20-23, 1989).

H. Hanerfeld, et al., "Higher Order Correlationsin Computed Particle Distributions," (SLAC-PUB-4916, Mar 1989; Presented at IEEE Particle Accel-erator Conf., Chicago, Ill., Mar 20-23, 1989).

T. Himel, "Calculation of Detector Backgrounds atTeV Linear Colliders," (SLAC-PUB-4804, Nov 1988;Contributed paper to DPF Summer Study Snowmass'88, High Energy Physics in the 1990's, Snowmass,Colo., Jun 27 - Jul 15, 1988).

T. Himel and K. Thompson, "Energy Measurementsfrom Betatron Oscillations," (SLAC-PUB-4917, Mar1989; Presented at IEEE Particle Accelerator Conf.,Chicago, Ill., Mar 20-23, 1989).

Robert Jacobsen and T. Mattison, "Beam Loss Mon-itors in the SLC Final Focus," (SLAC-PUB-4909,Mar 1989; Presented at IEEE Particle AcceleratorConf., Chicago, Ill., Mar 20-23, 1989).

I -- -

SLAC Beam Line, April 1989I--

Ralph G. Johnson, "Stanford Linear Collider His-tory Data Facility," (SLAC-PUB-4885, Mar 1989;Contributed to IEEE Particle Accelerator Conf.,Chicago, Ill., Mar 20-23, 1989).

S. Kheifets, et al., "Bunch Compression for the TLC:Preliminary Design," (SLAC-PUB-4802, Dec 1988;Contributed paper at DPF Summer Study: Snow-mass '88, High Energy Physics in the 1990's, Snow-mass, Colo., Jun 27 - Jul 15, 1988).

W. Kozanecki, "Where Do We Stand on the SLC?"(SLAC-PUB-4859, Feb 1989; Presented at Int. Conf.on Physics in Collision, Capri, Italy, Oct 19-21,1988).

G.A. Loew and J.W. Wang, "RF Breakdown andField Emission," (SLAC-PUB-4845, Jan 1989; Con-tributed to DPF Summer Study Snowmass '88, HighEnergy Physics in the 1990's, Snowmass, Colo., Jun27 - Jul 15, 1988).

T. Lohse and P. Emma, "Linear Fitting of BPMOrbits and Lattice Parameters," (SLAC-CN-371,February 1989)

K.C. Moffeit, "Polarization at the SLC," (SLAC-PUB-4764, Oct 1988; Invited talk at Int. Symp. onHigh Energy Spin Physics, Minneapolis, Minn., Sep12-17, 1988).

Katsunobu Oide, "Final Focus System for TLC,"(SLAC-PUB-4806, Nov 1988; Contributed to DPFSummer Study on High Energy Physics in the 1990's,Snowmass, Colo., Jun 27 - Jul 15, 1988).

Katsunobu Oide and Kaoru Yokoya, "The CrabCrossing Scheme for Storage Ring Colliders,"(SLAC-PUB-4832, Jan 1989).

R.B. Palmer, "Energy Scaling, Crab Crossing andthe Pair Problem," (SLAC-PUB-4707, Dec 1988; In-vited talk given at DPF Summer Study Snowmass'88: High Energy Physics in the 1990's, Snowmass,Colo., Jun 27 - Jul 15, 1988).

J.M. Paterson, "PEP as a Synchrotron RadiationSource: Status and Review," (SLAC-PUB-4899, Mar1989; Invited talk given at IEEE Particle AcceleratorConf., Chicago, Ill., Mar 20-23, 1989).

T. Raubenheimer, et al., "Damping Ring Designs fora TeV Linear Collider," (SLAC-PUB-4808, Dec 1988;Contributed to DPF Summer Study: Snowmass '88,High Energy Physics in the 1990's, Snowmass, Colo.,Jun 27 - Jul 15, 1988).

T. Raubenheimer, et al., "A Damping Ring Designfor Future Linear Colliders," (SLAC-PUB-4912, Mar1989; Presented at IEEE Particle Accelerator Conf.,Chicago, Ill., Mar 20-23, 1989).

R.D. Ruth, "Progress on Next Generation Lin-ear Colliders," (SLAC-PUB-4848, Jan 1989; Con-tributed to Proceedings of U.S. Particle AcceleratorSchool., Batavia, Ill., Jul 20 - Aug 14, 1987).

R.D. Ruth, "Multibunch Energy Compensation,"(SLAC-PUB-4541, Feb 1989; Invited talk given atICFA/INFN Workshop on Physics of Linear Collid-ers, Capri, Italy, Jun 13-17, 1988).

J. Seeman, "Beam Dynamics Verification in Linacs ofLinear Colliders," (SLAC-PUB-4752, Jan 1989; In-vited talk given at 1988 Linear Accelerator Conf.,Linac '88, Williamsburg, Va., Oct 3-7, 1988).

R. Siemann, et al., "Report of the B Factory Group.2. Accelerator Technology," (SLAC-PUB-4839, Jan1989; Contributed DPF Summer Study: Snowmass'88, High Energy Physics in the 1990's, Snowmass,CO, Jun 27 - Jul 15, 1988).

K. Thompson and R.D. Ruth, "Multibunch Insta-bilities in Subsystems of 0.5-TeV and 1-TeV LinearColliders," (SLAC-PUB-4800, Nov 1988; Presentedat DPF Summer Study, Snowmass '88, High EnergyPhysics in the 1990's, Snowmass, Colo, Jun 27 - Jul15, 1988).

K. Thompson and R.D. Ruth, "Controlling Multi-bunch Beam Breakup in TeV Linear Colliders,"(SLAC-PUB-4537, Jan 1989; Presented at Workshopon the Physics of Linear Colliders, Capri, Italy, Jun13-17, 1988).

K. Thompson and R.D. Ruth, "Multibunch BeamBreakup in High-Energy Linear Colliders," (SLAC-PUB-4873, Mar 1989; Presented at IEEE ParticleAccelerator Conf., Chicago, Ill., Mar 20-23, 1989).

K. Thompson, et al., "Operational Experience withModel Based Steering in the SLC Linac," (SLAC-PUB-4874, Mar 1989; Presented at IEEE ParticleAccelerator Conf., Chicago, Il., Mar 20-23, 1989).

J.W. Wang and G.A. Loew, "RF Breakdown Studiesin Copper Electron Linac Structures," (SLAC-PUB-4866, Mar 1989; Presented at IEEE Particle Accel-erator Conf., Chicago, Ill., Mar 20-23, 1989).

J. Weaver, et al., "Design, Analysis and Mea-surement of Very Fast Kicker Magnets at SLAC,"(SLAC-PUB-4897, Mar 1989; Contributed to IEEEParticle Accelerator Conf., Chicago, Ill., Mar 20-23,1989).

P.B. Wilson, "RF Pulse Compression and Alterna-tive RF Sources for Linear Colliders," (SLAC-PUB-4803, Dec 1988; Contributed to DPF Summer Study:Snowmass '88, High Energy Physics in the 1990's,Snowmass, Colo., Jun 27 - Jul 15, 1988).

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P.B. Wilson, "Introduction to Wake Fields andWake Potentials," (SLAC-PUB-4547, Jan 1989;Contributed to U.S. Particle Accelerator School,Batavia, Ill., Jul 20 - Aug 14, 1987).

Instrumentation and Techniques

J.V. Allaby, et al., "The MAC Detector," (SLAC-PUB-4833, Feb 1989; Submitted to Nucl. Instrum.Methods).

W. Ash, "Final Focus Supports for a TeV LinearCollider," (SLAC-PUB-4782, Nov 1988; Contributedpaper at DPF Summer Study Snowmass '88, HighEnergy Physics in the 1990's, Snowmass, Colo., Jun27 - Jul 15, 1988).

D. Aston, et al., "Development of CRID Single Elec-tron Wire Detector," (SLAC-PUB-4875, Feb 1989;Presented at Int. Wire Chamber Conf., Vienna, Aus-tria, Feb 13-17, 1989).

A.C. Benvenuti, et al., "A Nonflammable Gas Mix-ture for Plastic Limited Streamer Tubes," (SLAC-PUB-4687, Mar 1989; Submitted to Nucl. Instrum.Methods).

G.B. Bowden, et al., "Retractable Carbon Fiber Tar-gets for Measuring Beam Profiles at the SLC Colli-sion Point," (SLAC-PUB-4744, Jan 1989; Submittedto Nucl. Instrum. Methods).

R. Cassell and F. Villa, "High Speed Switching inGases," (SLAC-PUB-4858, Feb 1989; Invited talkgiven at 4th Workshop: Pulse Power Techniques forFuture Accelerators, Erice, Italy, Mar 4-9, 1989).

K.R. Eppley, "Design of a 100-Mw X-Band Klystron,"(SLAC-PUB-4900, Feb 1989; Contributed to IEEEParticle Accelerator Conf., Chicago, Ill., Mar 20-23,1989).

Z.D. Farkas, "Radiofrequency Pulse Compression,"(SLAC-PUB-4820, Dec 1988; Invited paper givenat Workshop on Physics of Linear Colliders, Capri,Italy, Jun 13-17, 1988).

Z.D. Farkas, et al., "RF Pulse Compression Experi-ment at SLAC," (SLAC-PUB-4911, Mar 1989; Pre-sented at IEEE Particle Accelerator Conf., Chicago,Ill., Mar 20-23, 1989).

Yehuda Goren and David U.L. Yu, "Computer AidedDesign of Three Dimensional Wave Guide LoadedCavities," (SLAC/AP-073, Feb 1989).

G. Hanson, et al., "Tracking Simulation and WireChamber Requirements for the SSC," (SLAC-PUB-4805, Nov 1988; Presented at Conf. on Future Direc-tions in Detector R&D Experiments at pp Colliders,1988 Summer Study on High Energy Physics in the1990's, Snowmass, CO, Jul 5-7, 1988).

G. Hanson, et al., "Wire Chamber Requirementsand Tracking Simulation Studies for Tracking Sys-tems at the Superconducting Supercollider," (SLAC-PUB-4860, Feb 1989; Presented at Wire ChamberConf., Vienna, Austria, Feb 13-17, 1989).

W.B. Herrmannsfeldt, "Low Emittance ThermionicElectron Guns," (SLAC-PUB-4843, Jan 1989; Con-tributed to U.S. Particle Accelerator School, Batavia,Ill., Jul 20 - Aug 14, 1987).

King-Yuen Ng and Robert Lee Warnock, "Reac-tive Impedance of a Smooth Toroidal Chamber Be-low the Resonance Region," (SLAC-PUB-4783, Feb1989; Submitted to Phys. Rev. D).

S. Schwyn, et al., "Aerosol Generation by Spark Dis-charge," (SLAC-PUB-4817, Dec 1988; Submitted toJ. Aerosol Sci.).

E. Soderstrom, et al., "Fast Energy Spectrum andTransverse Beam Profile Monitoring and FeedbackSystems for the SLC Linac," (SLAC-PUB-4896, Mar1989; Contributed to Particle Accelerator Conf.,Chicago, Ill., Mar 20-23, 1989).

Robert Lee Warnock, et al., "Methods of Stabil-ity Analysis in Nonlinear Mechanics," (SLAC-PUB-4846, Jan 1989; Contributed to the Proc. of U.S.Particle Accelerator School, Batavia, Ill., Jul 20 -Aug 14, 1988).

Robert Lee Warnock, et al., "Construction andFourier Analysis of Invariant Surfaces from TrackingData," (SLAC-PUB-4927, Mar 1989; Presented atIEEE Particle Accelerator Conf., Chicago, Ill., Mar20-23, 1989).

Other Topics

William T. Achor, et al., "Fundamental Parti-cles and Interactions: a Wall Chart of ModernPhysics," (SLAC-PUB-4796, Dec 1988; Reprintedfrom Physics Teacher, p.556-565, Dec 1988).

David McGoveran and H. Pierre Noyes, "PhysicalNumerology?" (SLAC-PUB-4929, Mar 1989; Sub-mitted to J. Stat. Comput. Simulation).

H. Pierre Noyes, "Where We Are," (SLAC-PUB-4836, Jan 1989; Submitted to Proc. of 10th AnnualInt. Mtg. of Alternative Natural Philosophy Assoc.,Cambridge, England, Aug 25-28, 1988).

Fundamental Particles and Interactions Chart Com-mittee: Helen R. Quinn, et al., "Teachers' Re-source Book on Fundamental Particles and Interac-tions," (SLAC-PUB-4879, Jan 1989; To accompanythe FPICC Wall Chart).

SLAC Beam Line, April 19891I II

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SLAC PEOPLE IN THE NEWS

The 1989 Wolfgang K. H. Panofsky Prize has beenawarded to Richard Taylor of SLAC ExperimentalGroup A and Jerome Friedman and Henry Kendallof MIT for their leadership in the first deep-inelasticelectron scattering experiments. Sponsored by theDivision of Particles and Fields of the AmericanPhysical Society (APS), this prize is given annuallyto recognize outstanding achievements in experimen-tal particle physics. The award was presented toFriedman, Kendall and Taylor at the Baltimore APSmeeting held the first week of May.

According to the citation recognizing their achieve-ments, "These electron-nucleon scattering experi-ments, which were a vehicle for the discovery of the'scaling' phenomenon, gave the first direct evidencefor a charged, pointlike substructure inside the nu-cleon." Further experiments with electron, muon andneutrino probes established that these pointlike con-stituents were in fact the quarks predicted in 1964by Murray Gell-Mann and George Zweig. They alsosupplied the first evidence for the existence of glu-ons and provided experimental foundations for thedevelopment of QCD.

The leaders of the famous SLAC-MIT collabora-tion, Friedman, Kendall and Taylor were instrumen-tal in the conception and development of the EndStation A facilities during the 1960s. This power-ful complex of magnetic spectrometers (see photo onpage 6), detectors and computers -state-of-the-artequipment at the time -became the standard forlater fixed-target facilities at CERN and Fermilab.As testament to their far-sighted design, two of thethree spectrometers remain in productive use today,almost a quarter of a century after they were origi-nally built.

Led by Burton Richter and David Ritson, Exper-imental Groups C and F used the same spectrome-ters for studies of high-energy photon-nucleon colli-sions, while Friedman, Kendall and Taylor chose toconcentrate on elastic and inelastic electron-nucleonscattering. It proved to be a fortunate choice indeed.The SLAC-MIT experiments were what initially putSLAC on the map of high-energy physics.

Jack Steinberger of CERN, who shared the 1988Nobel Prize in physics, had the highest praise forthe SLAC-MIT experiment. Reviewing the field oflepton-nucleon scattering during Panofsky's 1984 re-tirement ceremonies, he observed that "No experi-ment in our time has had a greater impact on ourway of doing physics today."

In late December 1988, Professor Wolfgang Panof-sky, Director Emeritus of SLAC, was elected a for-eign member of the USSR Academy of Sciences.He was informed of his election in a telegram fromAcademy President G. I. Marchuk, who cited Panof-sky's scientific accomplishments in nuclear physicsand expressed his hope that this choice would "fur-ther strengthen the relations between USSR andUSA scientists."

Panofksy was one of only two U.S. scientistselected to the Soviet Academy in nuclear physics.The other was Professor Samuel Ting of M.I.T., whoshared the 1976 Nobel prize in physics with SLACDirector Burton Richter.

Panofksy came to Stanford from Berkeley in 1951and soon took the helm at the High-Energy PhysicsLaboratory down on campus. In 1961 he became thefirst Director of SLAC, remaining in that positionuntil 1984.

Since stepping down from that post, Panofsky hasbeen devoting most of his time to work on arms con-trol and future particle accelerators, including theSuperconducting Super Collider. He was a key advi-sor to Chinese physicists who designed and built theBeijing Electron-Positron Collider, now in the finalstates of its commissioning process.

When not away on one of his frequent trips, Piefcan be found almost daily at SLAC, working awayin his offices (dubbed Pief-a-Terre) on the first floorof the Central Laboratory.

* * *

Perry Baker Wilson was recently elected a Fellowof the American Physical Society. In honoring himthe APS cited his "significant theoretical and experi-mental contributions to accelerator science and tech-nology in the theory of particle beams and in thedevelopment of linear accelerators, RF superconduc-tivity, and high-power microwave techniques."

A Professor at SLAC (Applied Research), Wilsonis the leader of the Advanced Accelerator StudiesGroup. He devotes much of his time to research onRF pulse compression techniques and various othermethods of generating the intense microwave powerthat will be necessary for the next-generation of lin-ear colliders.

Wilson earned his Ph.D. in physics at Stanford in1958. He joined the SLAC Accelerator Departmentin 1969, and has worked here ever since.

- ichael Riordan

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DOUG DUPEN HEADS BACK TO CAMPUS

After spending over a quarter of a century at thelaboratory, Doug Dupen has accepted the position ofDeputy Manager of Employee Relations at StanfordUniversity. He will continue at SLAC on a part-timebasis, however, providing an important link betweenthe laboratory and campus. A multi-faceted per-son, Dupen plans to shoulder these new responsibili-ties while remaining involved in community relationsand serving as a knowledgeable member of the SLACstaff.

Though many have worked closely with Doug overthe years, few know the personal side of this quietman whose sense of humor is reflected in his extensivecollection of cartoons. Born in Sacramento, he holdsBA degrees in both Physics and Speech/English. Af-ter starting work at the laboratory in 1962, he earnedhis MS degree in Physical Sciences from StanfordUniversity in 1966. He and his wife Joanne have twosons, a daughter, and four grandchildren.

Doug's early interests included broadcasting. Hehas been an FCC licensed radio operator, an FAA li-censed pilot, and a DMV licensed bus driver. A con-scientious member of the community, he contributedtime and effort to local homeowners associations,worked with business, and even served as Mayor ofMenlo Park.

As the laboratory grew from Project M to thesprawling complex it is today, Doug grew with it.

From Technical Information Officer to Director ofPersonnel/Laboratory Relations he has worn manyhats -speaker, writer, supervisor, labor negotiatorand tour guide. Public speaking, handling the me-dia, and writing brochures describing the laboratoryare just a few of the activities that have involved hisenergies throughout his SLAC career.

Hosting conferences and tours with guests rang-ing from heads of state to the laboratory's neighbors,Doug has been able to convey enthusiasm for SLAC'swork to people from all walks of life. He has been

-and will continue to be -actively involved withthe Consortium, a program that supports minoritiesand women working towards graduate degrees in en-gineering.

Those who work with Doug will still find him inhis A&E office, occasionally burning the midnightoil as he makes progress on his infinite list of specialprojects.

Nina Adelman Stolar

Dupen chats with Marie Arnold of the SLACBenefits Office and cuts his cake during an April24 party given in his honor. (Photos by TomNakashima)

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SLAC Beam Line, April 1989I

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