Low p{sub T} photon production in proton-nucleus collisions at 18 GeV/c

Journal Article · Fri Oct 01 04:00:00 EDT 1993 · Bulletin of the American Physical Society

OSTI ID:387179

Tinckneol, M; Gomez Del Campo, J; Ray, A ^[1]

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1. and others

Low p{sub T} photon production has been measured in p+Be and p+W collisions at beam momenta of 10 and 18 GeV/c at the BNL AGS. Two arrays of BaF{sub 2} crystals were used to measure low energy photons with excellent energy resolution and good time resolution to supress backgrounds. Inclusive single photon spectra were measured in the p{sub T} range from {approx} 10 MeV/c up to {approx} 1 GeV/c at several rapidities in the interval from -2.1 < y{sub cm} < 0.5. These spectra were used to determine the p{sub T} and rapidity distributions of {pi}{sup 0}`s in the kinematic range for which decay photons from {pi}{sup 0}`s contribute to the single photon spectra. The measured photon distributions are compared with the distribution expected from {pi}{sup 0} decays and hadronic bremsstrahlung in a search for new sources of {open_quotes}soft{close_quotes} photons at low p{sub T}. Preliminary results from the p+Be data indicate no significant excess of low p{sub T} photon production at y{sub cm} = 0 above that which is expected from conventional sources. However, a small but significant excess of low p{sub T} photons is observed in the p+W data. Some of these photons may result from the decay of the excited target nucleus, and further investigation is currently under way to determine their origin.

• OSTI ID: 387179
• Report Number(s): CONF-931044--
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 9 Vol. 38; ISSN BAPSA6; ISSN 0003-0503
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BERYLLIUM 9 TARGET
ELECTROMAGNETIC PARTICLE DECAY
PHOTOPRODUCTION
PIONS NEUTRAL
PROTON REACTIONS
TRANSVERSE MOMENTUM
TUNGSTEN