Physics for ISABELLE

Bill Willis puts the case for heavy ion collisions at the recent ISABELLE Workshop at Brookhaven.

After the recent successes with the new prototype superconducting ca­ ble , the future of the ISA­ BELLE 400 GeV -proton stor­ age ring project at Brookhaven sud­ denly looks much brighter (see Octo­ ber issue, page 353). While there is lot of work which remains to be done before the machine becomes opera­ tional, it is not too early to look at the physics possibilities which ISA­ BELLE will offer when it turns on, hopefully in 1987. This physics potential was well covered during this year's ISABELLE Summer Workshop at Brookhaven, which attracted some 250 partici­ pants. As well as speculating about new physics, this meeting also got down to some detailed groundwork for experimental areas and detec­ tors. The wide range of physics oppor­ tunities offered by the machine's high design luminosity (in the 10 32-33 region) is well reflected in the variety of designs for large detectors which mary physics goal at ISABELLE is the / Columbia / Stony Brook collabora­ are emerging. With many exciting search for the unknown. Rather than tion which has already carried out developments afoot in the fields of describing it as offering a new win­ experimental tests of large arrays of detectors and data handling, confi­ dow on physics, Samios preferred to lead-glass counters. A detector des­ dence is high that a lot of good phy­ view ISABELLE as opening a 'barn ign with uranium plates in a dipole sics can be extracted. door', and likened other approaches field is being prepared by Brookha­ Introducing the sessions, work­ to 'peepholes'. ven, Columbia and Pennsylvania. A shop co-chairman Nick Samios un­ ISABELLE's contributions to phy­ lot of development has already gone derlined the attractions of proton- sics could cover many existing ideas into the design of a muon detector proton machines — high energy and — properties of weak bosons, and incorporating large drift chambers luminosity, dedicated use and a rela­ exploring the source of symmetry (signal wires 5 m long) by a highly tively large number of available beam breaking, whether the long-awaited international group with physicists intersection regions. He pointed out Higgs particles, or 'technicolour' from , Japan and China as the performance of ISABELLE's fore­ effects. Searches could be made for well as the US. The aim is to achieve runner proton-proton machine, the extremely heavy new quark-anti- a mass resolution of one per cent at CERN Intersecting Storage Rings, quark bound states. However the 100 GeV. Another effort involves a which has outstripped all expecta­ detectors would probably have to toroidal . tions and still improves. On the other adapt to new and possibly unfore­ From the discussions during the hand proton-antiproton colliders, the seen experimental conditions. sessions on large detectors, it was newcomers to the physics scene, The variety of detector designs concluded that the development of a cannot rival proton-proton luminosi­ were covered in sessions organized high precision vertex detector to de­ ties, and have to share available by C. Baltay and H. Gordon. LAPDOG tect rare particle decays would be beam time with fixed target experi­ is a high resolution spectrometer for useful. Later this year, the ISABELLE ments. , photons and neutral pions management will start to consider a Samios emphasized that the pri­ envisaged by a Brookhaven / Brown schedule for proposals to occupy the

CERN Courier, November 1981 391 machine's six beam intersection re­ lenge to detector specialists, both in collisions, ISABELLE, like the CERN gions. the adaptation of existing techniques ISR, could eventually find itself being Sessions on detector research and and the eventual use of new meth­ used to collide beams of particles development were organized by ods still at the prototype stage. heavier than . With these ad­ T. Ludlam and W. Carithers with the In summary, Samios said that the ditions, ISABELLE could provide in aim of assessing current detector meeting reaffirmed luminosity and Samios' view 'the cornerstone' of know-how for ISABELLE's high energy as ISABELLE's big selling the US high energy physics pro­ event rates and the requirement for points. Reactions (whatever they gramme. selective triggers. The usefulness of might turn out to be) with cross-sec­ a detector component would be gov­ tions as small as 10"35 cm 2 could be erned by its ability to select and investigated. Recalling what had record useful data using trigger pro­ happened elsewhere, Samios cessors, and efforts to improve se­ pointed out that it is not always the lectivity at the detector/processor earliest accelerator to turn on which level were deemed important. Calori­ produces the new results. It is im­ meters, the central elements of most portant to do things right as well as of the current detector designs, must fast', he declared. have good spatial and energy resolu­ In addition to the physics objec­ tion at relatively low cost. Improved tives, extensions of the original ISA- electronics could help with specific BELLE idea of proton-proton colli­ problems for wire chambers and drift sions are being put forward. An elec­ chambers. Particle identification un­ tron-proton option using 10-20 GeV der ISABELLE conditions has its own electrons looks feasible and has sti­ special problems. In all, the require­ mulated a lot of interest. With more ments provide a considerable chal­ results now coming in from heavy ion

Participants at the Workshop had the chance to see the construction progress for the ISABELLE ring and experimental areas.

(Photos Brookhaven)

392 CERN Courier, November 1981