Pions to Quarks

NEWS from the Summer Conferences will appear in our next issue. data last year, the noise seems to discussed evidence for the exist• The Symposium, which was un• be abating.) ence of the top quark based on der the auspices of Tel Aviv Uni• New preliminary results coming UA1 data. The quoted mass limits, versity, was ably organized by from the UA5 detector at the between 30 and 50 GeV, were de• Jacob Grunhaus, and all the par• CERN Collider caused a great stir. termined from semileptonic de• ticipants owe him a vote of thanks. The data was taken while operat• cays of W bosons. From Errol Gotsman ing the Collider in a pulsed mode John Ellis held the attention of at a record collision energy of 900 the audience with his talk on 'Su- GeV (see May issue, page 131). persymmetry and anything be• Pions to quarks John Rushbrooke made a beautiful yond the Standard Model in This was the title of an interna• presentation of the data, stressing hadron interactions,' however in tional symposium on particle the new features that are seen. the light of the new UA1 and UA2 physics in the 1950s, held at Fer- These include the fast increase of data presented by Peter Watkins milab from 1-4 May and which at• the average number of charged and Michele Livan, this lecture tracted 170 participants from ten particles with energy, and viola• took on a speculative tone. countries, as well as other visitors tion of so-called 'KNO' scaling Arnon Dar gave a fascinating from Fermilab and the surround• over the collision energy range survey of Cosmic Accelerators, a ing area. The main sessions dealt 200 to 900 GeV. A new form of topic which seems to have be• with new particle discoveries in scaling manifests itself in the cen• come an integral part of high en• the cosmic rays; with strong, tral region, and there is approxi• ergy physics, and a novel way of weak, and electromagnetic interac• mate scaling in the fragmentation studying reactions at ultra high tions; with accelerator and detec- (quark interaction) region. A energies. Recent data measured at search for Centauro-like events, the Fly's eye detector in Utah have Abdus Salam addresses the International seen in cosmic rays and possibly Symposium on Particle Physics in the confirmed that the source of the 1950s, held at Fermilab from 1-4 May. expected at these energies, turned ultra high energy cosmic rays and out to be negative. Gosta Ekspong, the 3K background radiation are also of UA5, showed that his ex• extragalactic and not local. The na• periment's particle multiplicity dis• ture of the ultra high energy neu• tributions could be well tral particles emanating from parametrized by a negative binom• Cygnus X-3, and other stars (see ial distribution, however the un• page 264) still remains an enigma. derlying mechanism remains a Summarizing the 59 papers pre• mystery. sented over the week, Harari The session on 'fragmentation' stressed the paucity of experimen• models was well attended. The tal clues that might suggest some• three most popular schemes for thing beyond the Standard Model describing the release of hadrons (SM) is required. Among the phe• by quarks and gluons were each nomena which cannot be accom• defended by a leading protago• modated in the SM, he mentioned nist: the case for the cluster model that if the universe is not baryon- by Bryan Webber, the Lund model antibaryon symmetric, or that mo- by Gosta Ekspong and the revised nojets exist, or CP symmetry is ad• Isajet model, including gluon ra• ditionally violated, then theoretic• diation corrections, by Frank ians will have something to occupy Paige. The first two models appear themselves. Until there is experi• to successfully reproduce the ex• mental confirmation for any of the perimental data, while Isajet still above phenomena, Harari feels has problems with at least elec• that the smart money is on quark tron-positron annihilation produc• substructure rather than super- ing three jets. Anne Kernan symmetry and grand unification. Arthur Roberts, one of the fathers of the Rochester Conference series, sings his fa• mous ballad "Take back your billion dollars and let's do physics again'. • (Photos Fermilab) tor developments; with social, political, and institutional dimen• sions of particle physics in the 1950s; and with the hopes and ex• pectations of particle physicists during that era. This symposium continued the historical work begun at an earlier symposium held at Fermilab in May 1980, devoted to the birth of particle physics in the 1930s and 1940s. The proceedings of that meeting - The Birth of Particle Physics edited by Laurie Brown and Lillian Hoddeson - was pub• lished by Cambridge University Press in 1983. More work has been needed to unravel the history of particle physics and bring it within reach of scholars and the public. The symposia identify the major con• tributors to the field and help to understand how the physics re• search fits into the larger context of science and culture. Finally the symposia examine science from a eries in cosmic rays were tor to the period, served as resi• long range perspective, thereby reviewed with Don Perkins (Ox• dent historian for the topic. helping to guide future projects. ford) covering the emulsion work One of the most striking features For example, the course of particle and George Rochester (Durham) of the physics of the fifties was the physics in the fifties has important reviewing the cloud chamber re• advent of accelerators and the in• bearings on the proposal to con• sults. creasing sophistication of the de• struct a superaccelerator in the The rapidly evolving concept of tectors. Peter Galison (Stanford) 1990s. strong interactions was covered acted as the history rapporteur for Such meetings are also cross- with talks by a number of distin• the detectors while Ernest Courant cultural gatherings. They bring to• guished contributors. Robert Hof- (Brookhaven) and Mathew Sands gether humanists and scientists. stadter (Stanford) discussed (Santa Cruz) reviewed the acceler• An important distinguishing fea• nucleon structure as seen with ator developments. Owen Cham• ture of this history symposium electron scattering. Luis Alvarez berlain (Berkeley) knitted the two was that it included one or more and Willy Chinowksy (Berkeley) themes together with the story of historians of science as speakers noted the impact of hydrogen bub• the discovery of the antiproton at at nearly every session. For exam• ble chambers on progress in un• the Bevatron. ple, the opening session, intro• derstanding strange particles, The startling developments in duced by Leon Lederman while Robert Walker (Caltech) re• weak interactions were the subject (Fermilab), was shared by C.N. viewed the pion resonances seen of another session. One question - Yang (Stony Brook) and historian in photoproduction. Jack Steinber- why parity violation was not dis• John Heilbron (Berkeley). ger (CERN) reminisced about parti• covered earlier - was probed by The meeting covered the entire cles and their properties circa Allan Franklin (Colorado). Dick Dal- gamut of developments in the fif• 1950. Abraham Pais (Rockefeller), itz (Oxford), Val Telegdi (Zurich) ties. The important particle discov• an important theoretical contribu• and Val Fitch (Princeton) showed .

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