Antiproton Physics Research Articles

First Biennial Conference on Low Energy Antiproton Physics (LEAP 90)

First Biennial Conference on Low Energy Antiproton Physics (LEAP 90)

Some new features in low-energy antiproton physics

It is demonstrated that the recent experimental results show a large p-wave enhancement in p p scattering and annihilation. A theoretical explanation of this effect is given in the framework of a simple coupled channel model. The physical reason of the enhancement in question is the existence of near-threshold bound and resonant quasi-nuclear p-states in the N N system.

Antiproton physics with EHF

Antiproton physics with EHF

The Low Energy Antiproton Ring — LEAR

LEAR, a new facility for antiproton physics with intense and cold beams of antiprotons, started its physics programme at CERN during the last quarter of 1983.

Multiparticle production in antiproton collisions

The special interest in antinucleon-nucleon interactions is in particular connected with the unique possibility of studying annihilation reactions in which the initial baryons and antibaryons turn into mesons. A characteristic feature of these processes is the large multiplicity of produced particles (as compared with other reactions where about half the c.m. energy is carried off by leading particles) which allows one to study multiparticle production even at relatively low energy. This interest is reflected by the fact that a whole series of Conferences has been devoted to IVNinteractions: Chexbres (1972), Liblice-Prague (1974), Stockholm (1976), BarrStrasbourg (1978), Bressanone (1980) and Santiago de Compostela (1982). Similar symposia have also been organized in Argonne (1958), Syracuse (1975) and LomaKoli (1975). These conferences embraced also other interesting topics of antiproton physics, such as ~-atoms, baryonium spectroscopy etc., which will certainly achieve a: new qualitative level in near future with the help of antiproton cooling devices (e.g., LEAR project [1]) due to the enormous increase in beam intensity by a factor of 103 and the amazing mass resolutions of a few keV. The new exciting data at very high energies are expected to appear from the pp-collider, ingeniously exploiting equal proton and antiproton masses and opposite charges to accelerate and collide them simultaneously in the same accelerator. In fact, interesting results on multiparticle production at 540 GeV in c.m.s, have recently been obtained [2, 3], e.g. clear hard parton jets have been observed allowing a check of quantum chromodynamics (QCD) predictions. I will concern myself mainly with the questions of multiparticle production in pp,interactions and also in other processes and will discuss the experimental data in terms of Regge phenomenology and quark-patton models (QM). It should be noted that the simplest QM based on SU(6) spin statistics [4, 5] predicted abundant resonance production in agreement with experiment. Since resonances yield more direct and richer information on the production mechanism, as compared with pions, kaons or nucleons, the study of resonance production is of great interest. *) Lecture given at the Arctic School of Physics 1982, Ak/islompo, Finland, August 1-- 13, 1982.

Operational Experience with the Superconducting High-Luminosity Insertion in the CERN Intersecting Storage Rings (ISR)

The eight superconducting quadrupoles and their cryogenic equipment for this insertion were installed in the ISR at the end of 1980. The insertion has been used to assess the problems of running a superconducting insertion in a storage ring as well as to provide high luminosity for physics. The luminosity is increased at intersection 8 by a factor of 7. By means of dedicated collimators and orbit corrections, safe working conditions could be established for the superconducting magnets during injection, accumulation, stable beam periods and when dumping the beams. Quenches were mainly caused by large accidental beam losses. Operating parameters for all standard beam energies, including acceleration to 31.4 GeV/c, have been established. At 26.6 GeV/c, with currents of 30.6 A in ring 1 and 30.3 A in ring 2, a luminosity of 1.4 1032 cm-2s-1 was obtained in the insertion. This is the highest luminosity reached so far in storage rings and it was obtained during a physics run. Satisfactory beam conditions could also be provided for antiproton physics at 26.6 GeV/c in ISR with both low-s insertions on, in I1 and I8, respectively.

A Project to Operate the CERN Intersecting Storage Rings (ISR) with Antiprotons

The storage of antiprotons in the ISR for proton - antiproton physics is planned for 1981, using the 3.5 GeV/c, cooled, antiproton source, which is currently being built at CERN. Two schemes have been studied for achieving this aim. Firstly, the antiprotons could be injected at 3.5 GeV/c from the cooling ring and accelerated in the ISR or secondly, they could be injected into the ISR at 26 GeV/c after acceleration in the CERN Proton Synchrotron (PS). Although the latter scheme is more expensive, since it requires a new transfer line, it has been adopted as it is operationally more reliable and as it makes it possible to stack the antiprotons. With five full-intensity pulses, the circulating antiproton current would be 0.15 A, which, with a 30 A proton beam, would yield a luminosity of 1.3 × 1029 cm-2s-1 in a standard intersection and 9.2 × 1029 cm-2s-1 with the planned superconducting low-s scheme.