The 1992 workshop on Recent Developments in the Phenomenology of Particle Physics, held in October at the International Centre for Theoretical Physics, Trieste, Italy, and locally organized by Faheem Hussain (left) and by Nello Paver (right, of Trieste University), covered all aspects of modern quantitative research.
TRIESTE Feet on the ground
Established in 1964 by Abdus Salam, the International Centre for Theoreti cal Physics (ICTP), in Trieste, Italy, has naturally become one of the world's leading centres of particle physics theory. Attracting distin guished senior visitors from all over the world and with a full programme of regular symposia and workshops, it provides a valuable stepping stone to frontier research for young re searchers, particularly those from the developing countries, who would otherwise find it tough to make headway in this competitive field. Initial ICTP research interests concentrated on particle physics and plasma physics, but as interest, support and infrastructure steadily expanded, these interests widened to give a truly interdisciplinary centre with active groups in fundamental fundamental physics, be it the gen cated analyses, there is ample physics, condensed matter physics, esis of the Standard Model in the room for phenomenologists to get mathematics, plasma physics, 1960s, or supersymmetry in the 70s, aboard. superconductivity, aeronomy, micro to the more esoteric recent develop To underline and encourage this processors, climatology, and in laser, ments. In the 1980s, when shift in emphasis, in 1991 ICTP atomic and molecular physics. superstrings and other ambitious launched a workshop on phenom Originally set up under the auspices schemes for a grand picture of enology, the idea being to bring of UNESCO and the International fundamental interactions were in together the results and implications Atomic Energy Agency, ICTP has vogue, it was natural and welcome of modern precision measurements in recent years been funded mainly for ICTP to concentrate its efforts in and encourage participation in this by Italy. 1991 saw a hiatus in ICTP these fields. new style of 1990s research. funding (December 1991, page 30). But times have changed. Like the The 1992 workshop, held in Octo However the financial status of the downbeat world in which it lives, ber in collaboration with the Italian Centre is now secure as the Italian 1990s physics has discarded, at INFN and locally organized by government has approved support least temporarily, many luxuries and Faheem Hussain and by Nello Paver for the next eight years. With the frills to concentrate instead on (of Trieste University), provided an International School for Advanced basics. Spearheaded by the preci impressive scientific programme Studies a close neighbour and the sion measurements at CERN's covering all aspects of modern university a short distance away, LEP electron-positron collider, there quantitative research. Young re Trieste will surely remain an impor is a resurgence of worldwide interest searchers emerged with a well- tant research centre. in numerical accuracy and the rounded picture of frontier phenom In spite of having no major experi productive phenomenology which enology and collected many useful mental physics activity on site, ICTP comes in its wake. With experiments indications of where contributions are has always been at the forefront of increasingly encountering compli welcome.
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CERN Courier, January/February 1993 27 Around the Laboratories
The programme covered neutrino are only two experiments) as well as physics, LEP results and their impli FERMILAB total separation during injection, cations as tests of the Standard acceleration and low beta squeeze. Model and indications of any physics Tevatron upgrade The beams are brought into collision beyond, and heavy quark physics, at only two points when low beta is particularly the 'effective theory' for The Fermilab accelerator complex is reached. calculations. With a formalism con in the middle of a major upgrade to In contrast with LEP at CERN and structed from general symmetry increase the luminosity beyond the Cornell's CESR ring (both electron- principles, this approach sets out to original design goal. During Phase I positron collides), the Tevatron uses make calculations based on a series of this upgrade, there have been separators in both the horizontal and expansion in the reciprocal of the major modifications to the Tevatron. vertical planes to produce a helical quark mass, so that the heavier the These modifications were commis orbit. A helical orbit is accomplished quark, the faster the expansion sioned at the start of the latest by creating a betatron oscillation in converges. collider run and include the installa the horizontal and vertical plane such While heavy quark effective theory tion of electrostatic separators to that the phase between the two brings no new physics, it greatly separate the orbits of the stored oscillations is rW2 where n is an odd simplifies the description of heavy beams and new low beta insertions integer. Helical orbits were chosen to flavour reactions. It was singled out to squeeze the colliding proton and keep the beams separated every by Steve Weinberg in his summary antiproton beams at both experiment where in the ring so that when the at the major international meeting interaction regions. position of the bunches was cogged in Dallas last year (October 1992, These modifications have already from the injection location to the page 1) as being particularly promis enabled the Tevatron to achieve a collision location the beams remain ing. record peak luminosity of 6.93 x 1030 separated. Highly relevant in this context was a per sq cm per s and a record weekly The design goals were a minimum measurement (presented by Giorgio integrated luminosity of 1060 inverse separation of 5 sigma and a maxi Romano) from the WA75 emulsion nanobarns. The peak goal for the mum separation of 15 mm between experiment at CERN of the purely present run of 5.0 x 1030 has already beam centres. This goal has been leptonic branching ratio of mesons been exceeded. met. Operation has used separators carrying both charm and strange In the 1989 collider run the record as small as 3 sigma with no prob
30 quantum numbers (Ds). luminosity was 2.07 x 10 . The lems. The separators have been very Tevatron was operated with six reliable. There has been only one bunches colliding head-on in all separator spark during operations to locations (twelve collision points). date (1000 hours). The observed One of the luminosity limiting factors spark did not appreciably affect the was a maximum sustainable tune store in progress. shift of .025 due to the beam-beam During injection, acceleration and interaction. A similar value has also the low beta squeeze separation is been achieved at CERN with a achieved using the horizontal separa different working point in the tune tors at B17 and vertical separators at diagram and with different bunch C17. During the injection process the parameters. In addition to a tune horizontal separator at B11 is used to shift, the beam-beam interaction adjust the phase of the helix through causes a tune spread across the the injection Lambertson. Finally, the beam and enhances the strength of beams are brought into collision at various destructive non-linear B0 and DO and kept apart every resonances. In the Tevatron, where else with local electrostatic resonances up to 12th order must be three bumps in each plane. One pair avoided. An orbit separation scheme of bumps creates a helical orbit from was developed to eliminate the B11 to C49. The other pair of bumps unnecessary collision points (there keeps the beam apart from D11 to
28 CERN Courier, January/February 1993