Physics monitor

Graham Ross of Oxford - looking beyond the Standard Model

ty) is not conserved (spontaneously Looking for violated) so that even the lightest new physics supersymmetric particle, stable un­ der R parity conservation, becomes unstable. The problem with the Standard Such processes could provide Model of particle physics is that novel signatures at LEP and/or at a while it is very successful, its pre­ tau factory (July/August, page 13), dictive power has run out of steam. and the underlying physics could A major objective now is to look help in understanding the long­ beyond this Model - the twin pic­ standing deficit of observed solar ture of particle physics in terms of neutrinos. the electroweak unification of elec- In the neutrino sector, the claims tromagnetism and the weak force and counter-claims for a 17 keV on one hand and the quantum particle (April, page 9) were reex­ chromodynamics theory of inter- amined, but no conclusions can yet quark forces on the other - to find be drawn. The solar neutrino ses­ out why it works so well. sion was enlivened by new results Thus the implications of recent from the American Germanium Ex­ accelerator and underground exper­ periment (SAGE), given by Tom iments came under scrutiny at a re­ Bowles of Los Alamos. He pre­ Corpuscular (IFIC) and sponsored cent International Workshop on El­ sented a series of measurements by Universidad Internacional Men- ectroweak Physics Beyond the carried out this year with 50 tons endez Pelayo (UIMP-Valencia) and Standard Model held in Valencia, of gallium. Taken at face value, other Spanish agencies. Spain. these results support the classic Supersymmetry is the most pop­ deficiency of solar particles seen From Jose. W.F. Valle ular way to extend the electroweak by the Kamiokande and Homestake sector for a deeper understanding. detectors. At Valencia, this was reviewed by The implications of solar neutri­ Electron-positron Graham Ross (Oxford) and by Luis no results were explored by spe­ Ibanez (CERN). Ross argued that cialists John Bahcall of Princeton colliders: looking at the minimal supersymmetric unified and Alexei Smirnov of Moscow future physics models are remarkably consistent (currently at Valencia). Taking the with precision low energy and LEP 17 keV neutrino seriously, organ­ data (April, page 3). izer Jose Valle showed how it With research and development This consistency underlines the could be reconciled with the solar work underway throughout the need to search for signs of super- neutrino observations. The out­ world towards high energy elec­ symmetry, where LEP has already come should be testable in the tron-positron linear colliders (April, contributed in several ways. One is next generation of solar neutrino page 10), interest turns to the new the search for supersymmetric experiments and laboratory physics these machines would Higgs bosons, a subject discussed searches for neutrino conversions. open up. by Spanish theorist M. Quiros, who The meeting concluded by look­ The first International Workshop stressed the importance of includ­ ing at the physics which will be on Physics and Experiments with ing radiative corrections in the ex­ opened up by increased energy at Linear Colliders was held recently perimental analyses. CERN's LEP electron-positron col­ in Saariselka in Finnish Lapland - There was also an interesting lider, by CERN's proposed LHC some 300 kilometres north of the presentation by Portuguese theorist proton collider, and by the Tau- Arctic Circle. The consensus was Jorge Romao on the rare decays Charm Factory now being dis­ that a compelling programme of expected in supersymmetric mod­ cussed in Spain. physics would be opened up by els where the conventional super- The Valencia meeting was colliders reaching 300-500 GeV, symmetry quantum number (R pari­ organized by Instituto de Fisica the major topics being precision

20 CERN Courier, December 1991 Technopolis Thoiry Geneva Moves With The Times

Geneva has been closely linked to science from the time it hosted crucial discussions on links between such diverse phenomena as light, chemical reactions and magnetism. Indeed, the city became the home of one of Europe's first major experimental facilities — a giant electrochemical pile designed to test Ampere's theories. This was built by de Saussure two decades after a visit by Volta to demonstrate a more famous, but much smaller, pile on his way to impress Napoleon.

An International Role The Opus One building at Technopolis Thoiry. Geneva's role in providing a testbed for unified theories of matter continues to this day at CERN where the LEP collider probes nature at the 10"18 metre scale by colliding elec­ trons and positrons circulating inside a high vacuum beam pipe buried up to 100 metres Focussing on Applied Physics below the Swiss and French countryside in a 27 kilometre circular tunnel. LHC, CERN's next major collider, proposed for the LEP tunnel, follows on from past CERN was conceived by scientists and politicians in the late-1940's as a step on the road achievements in calling for state-of-the-art superconducting magnets, advanced mate­ to post-war reconciliation via a major collaboration on the neutral ground of pure rials, sophisticated vacuum and cryogenic systems, high power electronics, and a wide research in a region with a long history of internationalism. With a staff of 3000 and a range of computer-based facilities to serve all aspects of the machine — from resource budget of some 900 million Swiss francs to provide facilities for scientists from 300 insti­ management to the imaging of particle collisions in its mega-detectors. tutes, CERN welcomes 6200 visitors each year. Technopolis aims to allow industry and institutes to participate in, and contribute to, the rich scientific and technical environment by serving as a closeknit interactive base for The Technopole Interface specialist organizations. In addition to enjoying a convenient window on CERN's exten­ Geneva continues to adapt its role as we move towards the 21st Century. Science parks sive sub-contracted requirements, they will be able to arrange collaboration on a formal represent one development and there are now about 300 in the industrialized world. In basis. Technopolis is also working to establish an Institute to provide an interface in offering a homogeneous blend of activities and facilities, they generally aim to enhance applied physics between teaching and research staffs, postgraduates and high calibre synergies in an increasingly competitive world. technicians coming from industry and R. and D. centres.

Unique among the science park concept is the Technopole approach where an outer A Superb Environment circle of commercial, governmental and institutional interests come together to promote an inner core of activities providing interfaces between science, technology, new busi­ Robert Hinterberger, Director of a Technopolis Thoiry based computer software com­ nesses, and higher education. Each Technopolis thus comprises a homogeneous blend pany, plages great importance on the "perfect working environment". This will continue of facilities and ancilliary services. to be preserved in a balanced development comprising space reserved for accomoda­ tion, technical and commercial companies, the technological institute, small scale R. and The Geneva region's Technopolis is situated just across the Franco-Swiss border from D. units, and hotels and conference services. the main CERN campus. The 27 hectare green field site on the outskirts of the village of Thoiry is therefore ideally located to interface with the international physics community. By the same token, while Mr. Benier, the Mayor of Thoiry, is "obviously interested in pro­ Being only five kilometres by road from Geneva's international airport and main line moting employment opportunities" he is "also concerned that we preserve the quality station is an invaluable advantage. of our local environment". Hence recent agreements for a national park in the Jura moun­ tains behind Thoiry, consolidation of road access from Switzerland through to the French motorway system, a cultural centre, a second international school, and the imminent construction of a major world-class shopping centre. Looking across the main CERN campus to Geneva from Technopolis Thoiry, outlined as an artist's image.

Organizations and companies wishing to set up at Technopolis Thoiry can choose between: - buying either complete buildings or office and technical space within a specific building; - renting floor space; - building to their requirements on a purchased plot.

For further information or to explore possibilities, please contact:

Technopolis Thoiry 1, avenue du Mont-Blanc Tel.: +(33) 50 42 02 02 F-01710 Thoiry, France Fax; +(33) 50 20 66 09

32 Circle advertisement number on reader service form At the recent electron-positron linear collider physics workshop in Saariselka in Finland, Bjom Wiik of DESY addressed the three big questions for such a machine - do we need it?, do we know how to build it?, and how do we get it?

These limits exceed the grasp of increased LEP energy, but are well within the reach of the next linear collider. A supersymmetry working group has concluded that a linear collider with a collision energy of 500 GeV is guaranteed either to find at least one Higgs (and most probably three neutral states and the charged states), or the Minimal Supersymmetric Standard Model will be ruled out. These new states generally appear with intermediate masses and investigation at hadron colliders is difficult. Historically electron-positron col­ liders have been ideal hunting grounds for new particles, and a wide variety of goals and strategies were presented at the workshop, covering such exotica as heavy Ma- jorana neutrinos and new vector bosons as well the more familiar predictions of supersymmetry. top quark physics, the physics of Another new sector would be On the machine side, control and gauge (W and Z) bosons, hunting the physics of W and Z boson in­ measurement of the beam energy for Higgs pgrticles, and new parti­ teractions. The static magnetic di- profile and of the beamstrahl spec­ cle searches. pole and electric quadrupole mom­ tra created during the beam-beam It looks as though the long ents of the charged W bosons interaction was considered to be awaited sixth ('top') quark will be could be measured more accurately important for much of the dis­ heavier than the W and Z boson than at LEP and at hadron colliders. cussed physics programme. carriers of the weak force. Under­ The study of W-W scattering Experience with the SLC Stan­ standing the role of the top quark will require TeV collision energies ford Linear Collider has shown that is an important goal, and analysis and very high luminosities, and will the detectors are an integral part of techniques and machine paramet­ be left for a future generation col­ the machine, and control of back­ ers were discussed and developed. lider. grounds is a challenge for accelera­ Scanning the threshold of top In the search for (scalar) Higgs tor physicists and particle physi­ quark production will fix the mass particles no loophole must be left. cists afike. to better than 500 MeV. This will Data samples well below the per­ Problems in beam collimation help understand the spectrum of formance expectations of various and detector shielding are being at­ quark masses, and, combined with machine designs will be sufficient tacked by a growing number of ac­ high precision measurements from to illuminate even the most com­ celerator and particle physicists, CERN's LEP and the precision plex Higgs spectra. As with LEP, especially the calculation of back­ measurements of the W mass from these studies are limited only by grounds produced in the interac­ the Fermilab Tevatron and from in­ the energy of the machine - tions of small intense beams. creasing the LEP energy, will con­ masses up to about 70% of the to­ The peripheral photon flux ac­ strain the mass of the Higgs parti­ tal energy are accessible. companying electron beams grows cle to about 20 per cent. Detailed Recent calculations increase the with energy and can lead to elec­ studies of the top quark, including upper limit on Higgs masses that tromagnetic and hadronic back­ its electroweak interactions and de­ can be tolerated by the Minimal Su- grounds if the luminosity produced cay properties, will be possible. persymmetric Standard Model. by the collider within the resolving

22 CERN Courier, December 1991 The island of Capri - scene of the second International Conference on Calorimetry in High Energy Physics, held from 14-18 October.

(Photo Mimmo Jodice) time of the detector becomes too large. This ultimately will constrain machine designs to favour higher repetition rates and lower luminosi­ ties per bunch crossing. The physics opened up by such a collider will probe the most puzz­ ling problems of today's Standard Model and its proposed exten­ sions. As summary speaker Bjorn Wiik of DESY concluded - 'the phy­ sics programme of a 300 - 500 GeV electron-positron collider with luminosity of ten inverse femto- barns per year has unique features, and is complementary to that of the hadron colliders LHC and SSC. The machine will demand inter­ national collaboration. As Burt Richter emphasized in his introduc­ tory talk - 'the world high energy physics community must begin to lay the foundation with govern­ ments for broad international effort to push this research frontier for­ periments at future big proton col­ mance of large systems, summar­ ward'. liders - the LHC at CERN and the ized on the final day by the parallel The meeting, jointly sponsored Superconducting Supercollider session conveners. by the International Committee on (SSC) in the USA. The picture which emerged Future Accelerators (ICFA), DESY The high energy and luminosity shows a large range of ongoing and CERN, and organized by the of those machines, together with R&D covering almost all calorimeter Finnish Institute for High Energy the short bunch crossing interval, is technologies and often involving Physics (SEFT), was attended by a real challenge for any detector experimental setups on the scale of 150 physicists from laboratories and in particular for calorimeters. small experiments. and universities in Europe, Russia, Moreover the large number of read­ Interesting results were pre­ Japan and America. The next out channels strongly constrains sented on the different options for workshop in the series will be held the cost of the detectors. LHC and SSC detectors - scintillat­ on the balmy shores of Hawaii in The Conference began with a ing fibres and tiles, ionization calo­ the Spring of 1993. series of review talks on general is­ rimeters (mostly liquid argon) and sues - performance limitations, crystals (for very accurate energy physics requirements, experience measurements). Important issues with existing large systems, large on radiation hardness, fast readout DETECTORS scale engineering, radiation damage electronics and actual realization of Calorimeters at Capri calculations, readout electronics, complex systems were also exam­ simulation studies, and applications ined. in non-accelerator physics. The session on physics require­ The second International Confer­ Subsequent parallel sessions ments established a direct link be­ ence on Calorimetry in High Energy covered physics requirements on tween the physics motivation of Physics, held from 14-18 October calorimetry, scintillation calorimet­ the future experiments and the on the island of Capri, included a ers, ionization calorimeters, homo­ choice of specific calorimetric de­ workshop dedicated to the import­ geneous calorimeters, electronics, tectors. Concluding the conference, ant problem of calorimetry for ex­ radiation hardness and perfor­ Klaus Pretzl of Berne stressed the

CERN Courier, December 1991 23