LEP dominates LP-HEP

Janet Carter of Cambridge and Opal - Preci­ sion tests of the Standard Model with LEP.

CERN's LEP electron-positron col­ lider was the star of this year's ma­ jor physics meeting - the Joint In­ ternational Lepton-Photon Sympo­ sium and Europhysics Conference on High Energy Physics (LP-HEP) - held in Geneva from 25 July - 1 August. All major results so far from LEP, and there are plenty of them, are in accord with the Standard Model of physics - a dual picture with the el- ectroweak unification of the elec­ tromagnetic and weak nuclear forces on one hand coupled with the quantum chromodynamics (QCD) field theory of inter-quark forces on the other. Summarizing the meeting, CERN Director General Carlo Rubbia pointed out the need to probe this picture in as much detail as pos­ sible. Far from being a closed book, the Standard Model covers a lot of uncharted territory, with the long-awaited sixth ('top') quark and the neutrino sector still being 'terra incognita', while the spontaneous symmetry breaking ('Higgs') me­ chanism at the heart of the elec- troweak unification, and the details of QCD dynamics, are still far from clear. LEP apart, the meeting reflected the continuing reluctance of the neutrino to give up all its secrets. The long-standing difficulty of pin­ ning down the delicate violation of combined particle/antiparticle 'beauty') quark, and the contribu­ Closing the meeting, Sheldon left/right switching (CP) symmetry, tions which could be made with the Glashow of Harvard highlighted the known for more than a quarter of a next generation of proton colliders. changing face of physics. For a century but still not understood, In their keynote talks on the final century, researchers had been used was also a talking point. For both day, Rubbia and neutrino summariz- to a steady stream of surprises to neutrino and CP-violation physics, er Rudolf Mossbauer surmised that keep them on their toes and stimu­ insights from new areas are eagerly the lower energy region, relying on late thinking. According to Gla­ awaited. reactors and the Sun, would supply show, the last major particle phy­ With CP violation effects so far the bulk of new neutrino informa­ sics surprise dates back to 1977, confined to the neutral kaon sector, tion. Mossbauer also looked for­ with the discovery of the fifth Rubbia pointed out the need for ad­ ward to the advent of cryogenic quark through the upsilon particle ditional CP violation investigations detectors to open up new neutrino at Fermilab. using B mesons (carrying the fifth fields of study. The proposed big proton collid-

CERN Courier, September 1991 1 I Safety and ease in use is guaranteed by LEMO's self-latching system I Very small size allowing a high density of connectors I This series served as the norm for NIM-CAMAC-CD/N 549 widely used in nuclear physics I Impedance: 50 Q with VSWR < 1.2 up to 1.2 GHz LEMO P.O.Box 194 CH-1024 Ecublens Tel:+41/21/691.16.16 Fax:+41/21/691.16.26 I

jbergoz) SPARROW CROZET P.O. BOX 6102 01170 GEX, MISSISSIPPI STATE i it FRANCE , , ; / i l f ) ii I l i m I t i --^§,39762 USA TEL: 50 41 00 89 iiiiiiiiiifi i i i i s TEL: (601)324-0982 FAX: 50 41 01 99 _ FAX: (i The direct link from Macintosh II to CAMAC and VMEbus with full support in the Kmax environoment. ACCELERATOR AND MAGNET TECHNOLOGY METRAfto Ambitious La securite grace a FABS Technologies, Versatile Laboratories Une nouvelle ere de la technique de mesure avec des multimetres a and Distinguished commence. ABB INSTRUMENTATION SA presente «MetraHit», une serie Manufacturing de multimetres avec securite automatique! Les multimetres haut de gamme travaillent avec un tout nouveau concept de securite qui exclut

toutes les erreurs de manipulation dues a I'inattention ou au manque

d'habitude. Et cela, grace a TABS! ABS, I'automatisme de blocage de

securite des douilles • reduit les dangers pour les utilisateurs et les instal­ Injection Beamline with Beam Diagnostic System for the Cooler Synchrotron COSY (Forschungszentrum Julich) lations • augmente la securite contre la surcharge et le court-circuit

• abaisse de facon drastique les frais d'entretien • minimise le pour- Engineering and manufacturing for: centage des pannes. Simple, mais efficace! LABS fonctionne ainsi: si une Normal and superconducting accelerator systems gamme de tension est choisie, le cable de mesure ne peut pas etre Normal and superconducting magnet systems branche dans la douille pour effectuer une mesure de courant. Si le cable UHV vessels / chambers RF components / cavities de mesure est branche dans la douille de courant, on ne peut pas choisir Cryogenic components and systems unegammede tension.Seuls les multimetres MetraHit de ABB METRAWATT Beryllium windows Beam Diagnostics sont equipes de TABS!

Interatom GmbH ABB INSTRUMENTATION AG Accelerator and Magnet Technology Glattalstrasse 63, CH-8052 Zurich Friedrich-Ebert-StraBe W-5060 Bergisch Gladbach 1 Telephone 01/302 35 35 Germany Telefax 01/30217 49 Telephone + 49 22 04 84 22 88 Telefax + 49 22 04 84 30 45 202 5^° it

CERN Courier, September 1991 3 Thomas Hebbeker of Aachen and L3 - QCD studies with LEP

The presented LEP data included more than a million hadronic Z de­ cays seen by the four experiments combined. Janet Carter opened the plenary sessions, setting the tone with a mass of precision data on the Z resonance, together with di­ rectional effects in lepton pair pro­ duction, tau spin orientation, charged hadron production in gen­ eral and B meson production in particular all supporting the Stan­ dard Model and sharpening knowl­ edge of specific parameters. The consistency of this informa­ tion, combined with precision measurements from other experi­ ments, provides powerful limits on the top quark, now confidently pre­ dicted to live somewhere between 120 and 160 GeV. One suggestion of a non-stan­ dard effect had come recently from Aleph, where the level of electron- positron annihilations into two tau leptons accompanied by a pair of charged particles was significantly higher than the analogous channels with two muons and with two elec­ trons. In a parallel session, Sau-Lan Wu of Aleph revealed that the latest data do not continue this trend, which moreover is not seen by Al­ eph and Opal at LEP, nor by the Mark II detector at Stanford's SLC Linear Collider (S. Wagner). Another non-standard hint had ers - LHC at CERN. and the US Su­ to summarize results from all come from L3 (Juan Alcaraz) in the perconducting Supercollider (SSC) around the ring. parallels, where high energy pho­ - will surely reach beyond the For the subsequent plenaries, tons accompanying an electron-po­ Standard Model, declared Glashow, the LEP presentations featured a sitron pair invited an explanation. but until then the task is to exploit speaker from each of the four ex­ Standard Model theorists were un­ and test the existing picture. periments - Janet Carter of Cam­ convinced. Nowhere is this happening better bridge and Opal (Precision tests of Speaking on LEP QCD results, than at LEP. The four big experi­ the Standard Model), Thomas Heb­ Hebbeker pointed out the advan­ ments - Aleph, Delphi, L3 and Opal beker of Aachen and L3 (QCD tages of LEP for QCD measure­ - at CERN's big ring were deftly studies), Michel Davier of Orsay ments - high energy, high precision treated at the meeting, with parallel and Aleph (Searches for new parti­ and relative freedom from hadronic session speakers using their own cles), and Patrick Roudeau of Orsay masking (fragmentation) effects. results as pointers but being careful and Delphi (Heavy flavour physics). The coupling strength of quark in-

4 CERN Courier, September 1991 Rudolf Mossbauer -15 major neutrino ques­ tions still to be answered.

gy upgrade. Also preoccupied with Higgs were John Ellis of CERN and Graham Ross of Oxford, investigat­ ing possible Higgs dynamics in talks on the Status of the Electro- weak Sector and Beyond the Stan­ dard Model respectively. Looking at heavy quark produc­ tion at LEP, Roudeau showed how b quarks are a powerful probe of directional effects (forward-back­ ward asymmetry), although ac­ count has to be taken of B particle mixing. Charmed particles too are also a good source of Standard Model information and are begin­ ning to be studied, while the para­ meters of B mesons and tau lep- tons now benefit from LEP data. Guido Martinelli of Rome des­ cribed the status of QCD, showing how precision is improving and how more and more processes are becoming amenable to calculation. In this difficult work, approxima­ tions are always attractive, but Martinelli remarked that perhaps teractions (alpha-s) is measured in but highly important, mechanism. only the unseen sixth quark is hea­ both Z hadronic decays and in the Whatever it might be, and there is vy enough to use this approxima­ production of collimated 'jets' of precious little indication, LEP exper­ tion confidently. hadrons. Comparison of the pro­ iments have now ruled out a lot of Neutrino sessions can always be duction rates of particles containing lower energy territory, and the counted on for controversy. With heavy and light quarks shows that Higgs must be heavier than 57 reports of 17 keV neutrinos from alpha-s is independent of quark fla­ GeV. 'The Higgs hunt is now on in several experiments (John Simp­ vour, while the variation of jet pro­ earnest,' affirmed Davier. son, Guelph) in conflict with a duction shows how alpha-s is 'run­ When the top quark is finally range of null results, the neutrino ning' with energy. seen (all the smart money is on the sector was in relative disarray. The experiments are beginning CDF experiment at Fermilab's pro- Speaking on cosmology and par­ to probe many detailed hadronic ef­ ton-antiproton collider) it might ticle physics, M. Turner of Fermilab fects, including the production of clarify the Higgs, but several speak­ was also worried about the 17 keV hyperons, etc. The average number ers emphasized that this was not neutrino. 'It fits nothing, so if it ex­ of charged hadrons produced is necessarily the case. ists it has to be important,' he re­ just above 20. Initial surveys indi­ Guido Altarelli had updated a marked. Neutrino summarizer cate that hadron jets arising from new parametrization method to Mossbauer called for careful neutri­ gluons are softer and broader than analyse detailed behaviour and help no experimentation in a sector so those from quarks. correlate Standard Model and non- vital to physics progress. Remarka­ With no new particles yet to re­ SM effects. This sort of evidence, bly little is known about such an port from LEP, Michel Davier con­ according to Davier, needs to be important particle, he admitted, dis­ centrated on the Higgs sector, monitored closely. On the evidence playing a list of no less than 15 where LEP is at last beginning to so far, Rubbia did not rule out a major neutrino questions still await­ shed some light on this obscure. Higgs sighting at LEP after its ener­ ing an answer.

CERN Courier, September 1991 5 During the Joint International Lepton-Photon Prize of the European Physical Society in re­ Symposium and Europhysics Conference on cognition of his many outstanding contribu­ High Energy Physics in Geneva in July, di­ tions to the subject. July. The prize was first stinguished Italian theorist Nicola Cabibbo awarded in 1989, when the recipient was (left), who is President of the Istituto Nazio- Georges Charpak of CERN. Right is European nale di Fisica Nucleare, was awarded this Physical Society President Maurice Jacob. year's High Energy and Particle Physics

Merging conferences

This year's big physics meeting in Geneva was, as its convoluted name suggests, a one-off merger between two traditional series of biennial international conferences on high energy physics - the Lepton-Photon Symposium spon­ sored by the International Union of Pure and Applied Physics (IU- PAP), and the Europhysics meet­ ing organized by the European Physical Society. These meetings take place in odd-numbered years, with the Lepton-Photon event preferring a venue associated with an elec­ tron machine. With LEP now marking CERN's debut as an elec­ tron Laboratory, this year's merg­ er in Geneva was particularly apt. Even-numbered years see the traditional IUPAP 'Rochester' meetings, whose worldwide ve­ nues aim to reflect the growing geographical spread of high ener­ Prominent among them is the so­ With mixing well known and fair­ gy physics activity (Singapore in lar neutrino puzzle, where the flux ly accurately measured in the quark 1990, Munich in 1988, Berkeley of particles coming from the sun is sector, it is interesting to speculate in 1986, Leipzig in 1984, Paris in considerably less than the ex­ on what physics would look like if 1982.) Next year's event had ori­ pected value. New experiments - neutrinos behave in a similar way. ginally been scheduled for Mos­ Gallex in the Italian Gran Sasso Rubbia pointed out that the big cow, but Geneva IUPAP Particles Laboratory and SAGE in the USSR passive experiments needed to and Fields Commission Chairman - use gallium to get a more typical look at neutrino effects would also T. Fuji! announced that Moscow picture of the particles emerging be well suited to search for signs had backed down, and the 1992 from the deep solar interior, but it of proton decay, where the longest meeting would instead be held in Dallas, Texas, from 5-12 August. is still too early for these new lifetime from minimal grand unifica­ In 1993, the Lepton-Photon studies to contribute. Barry Barish, tion schemes has long been ruled and Europhysics events once summarizing non-accelerator exper­ out, but where other schemes more go their separate ways, in iments, looked forward to a first could still allow a tiny hole for ba­ Cornell (US) and Marseille crop of gallium solar neutrino data sic nuclear instability. respectively. next year. A relatively new feature of the In the coming year, the IUPAP Another outstanding neutrino neutrino sector is limitations on commission will review the rota­ question is neutrino masses. Moss­ neutrino parameters from cosmolo­ tion of venues for the Rochester bauer thought the improvement ex­ gy - reflecting the important role and Lepton-Photon series, includ­ pected from traditional measure­ these particles play in basic phy­ ing the definitions of the world sics. Graham Ross showed how regions on which the rotations ments is now limited, and that neu­ are based. trino oscillations - cyclic variations the 17 keV neutrino candidate is in neutrino type - would be more tightly constrained by cosmology. sensitive. Turner, in his cosmology talk, des-

6 CERN Courier, September 199 CKS NEWS : At last the long distance VME memory mapped CAMAC Crate Controller! VCC 2117: VICbus to CAMAC interface

Direct memory mapped CAMAC interface on • Up to 2 Mbytes global SRAM VIC bus • Can act in the CAMAC crate either as a CCA2 Optional 68030 List Processor, with dual ported or auxiliary crate controller memory and Ethernet controller • Transparent access and LAM handling Up to 1 Mbyte EPROM + 512 Kbytes SRAM • Fast transfer on the VICbus, 10 Mbytes/sec. local ressources

The board extends the VIC bus family directly to CAMAC and for maintenance and monitoring. makes it accessible to VME front end processors, UNIX/OS-9 • Multi-megabyte per second transfer speeds from CAMAC work stations, PCs and Macintoshes. It supports the complete achieved through parallelized read-out on the crate level. functionality of CAMAC and provides additional features for the most demanding applications using state of the art The VCC 2117 is delivered with OS-9 or Lynx-OS packages, technologies like memory broadcast, message posting, multi- including: NFS (if equipped with optional Ethernet), CAMAC mastership on the vertical bus, autonomous list driven intelligent driver and VMV/VIC data manager. crate read-out controllers. Up to 14 CAMAC crates can be connected to one 100 m VIC branch; parallel branches can be Both, modern data acquisition systems and monitoring and implemented. control systems, will benefit from the uniform interface to a number of popular peripheral buses. Any application requiring one or more of the following features is offered an optimal solution by this card: Associated modules: • Mixed systems with various peripheral buses accessible VIC 8250/1 -VIC terminator through a uniform interface in hardware and software (VME, VBAT 8218 - PC-AT to VMV interface VXI, FASTBUS, CAMAC) MAC 7212 - Mad I to VMV in ter face • Systems where direct access by personal computers is desired SVIC 7213 - SPARC to VMV/VIC interface

For these and our other VME, CAMAC and FASTBUS modules, contact us: Headquarters: CES Geneva, Switzerland Tel: (022) 792 57 45 Fax: (022) 792 57 48 CES.F France Tel: (33) 50 31 55 00 Fax: (33) 50 31 55 10 CES.D Germany Tel: (6055) 4023 Fax: (6055) 82 210 CES Creative Electronic Systems SA 70, Route du Pont-Butin Case Postale 107 CH-1213 PETIT-LANCY 1 SWITZERLAND cribed how nucleosynthesis follow­ from these two experiments have In the plenary session, J.-M. Ger­ ing the Big Bang excludes the tau come in with different values for a ard of Louvain looked hard at the neutrino mass from the range be­ parameter related to the 'ratio of framework of CP violation, where tween 0.5 and 25 MeV. With the ratios' - the relative decay rates of the limited room for CP violation ARGUS experiment at DESY indi­ long- and short-lived neutral kaons appears to hinge on limitations on cating it to be lighter than 35 MeV into neutral and charged pion pairs. quark transitions, and on empirical anyway, the tau neutrino does not Now each with samples of more isospin selection rules long known have a lot of room left. than two million neutral kaon de­ but still not understood. CP-violation can be accommo­ cays, the experiments do not ne­ Looking to the future, with plans dated in, but not explained by, the cessarily disagree, but the agree­ for complementary particle physics Standard Model. Two major high ment could be better, making any machines to attack the high energy precision experiments, one (NA31) precise interpretation difficult. and high precision frontiers. Carlo at CERN and the other (E731) at A fresh CP violation feature was Rubbia was optimistic. 'Nature has Fermilab, have for several years a preliminary result from the CP put the answer to many questions been patiently accumulating and LEAR experiment at CERN's low within our reach,' he concluded. analysing data on the decay of neu­ energy antiproton ring, where evi­ tral kaons into pairs of charged and dence has been seen for different neutral pions. decay properties of particle and an- Over the years, batches of data tiparticle. By Gordon Fraser

Computing in high energy physics

The increasingly important role The sessions began with John workstations, linked by networks. played by computing and comput­ Thresher (CERN) who raised var­ The transition appears to be coher­ ers in high energy physics is dis­ ious questions on the computing ent. played in the 'Computing in High environment of the 1990s - the David Williams (CERN) asked 'Is Energy Physics' series of confer­ major factors being evolution of the role of the mainframe termi­ ences, bringing together experts in computing environments due to nated ?', anticipating a rundown of different aspects of computing - appearance of high-performance the mainframe emphasis in the next physicists, computer scientists, microprocessor-based worksta­ five years. But he is still worried and vendors. tions and world-wide large collabo­ about performance of the distri­ The meetings have been held ev­ rations for experiments at the plan­ buted system in data I/O and soft­ ery one or two years since 1980 ned big hadron colliders (SSC/LHC). ware and operational stability with­ when the series was initiated in Bo­ K. Amako (KEK), M. Delfino (Barcel- out the mainframe. logna, and are traditionally organ­ ona,CERN), D. Notz (DESY), and L.R. Cormell (SSCL) reported on ized under the initiative of the local T.Nash (Fermilab) reported on the the recent installation of the com­ organizing committee. For the re­ current status of HEP computing in puter facilities at the US Supercon­ cent conference in Tsukuba, Japan, their respective laboratories, each ducting Supercollider (SSC) Labora­ the local organizing committee was facing the transition from main­ tory, where a 'farm' has been in­ chaired by Shinkichi Shibata of the frame-based centralized computing stalled for batch jobs and interac­ Japanese KEK Laboratory with an to a distributed or collective com­ tive front-end workstations for international advisory committee puting environment with various physics/detector simulation of SSC through the LISTSERV electronic types of machine - mainframe, su­ experiments. There is no main­ conference system. percomputer, computer farm, and frame-like system.

8 CERN Courier, September 1991