Bochum 1998 – wissenschaftliches Programm
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HK: Hadronen und Kerne
HK 46: Heavy Ion Reactions V, Ultrarelativistic Energies
HK 46.7: Vortrag
Mittwoch, 18. März 1998, 16:15–16:30, P
Measurement of Photons from 158 A GeV Pb+Pb Collisions at Low Transverse Momenta* — •K. Reygers1, C. Barlag1, S. Bathe1, C. Blume1, Z. B"or"ocz1, D. Bucher1, H. B"usching1, S. Gorus1, R. Glasow1, S. Joerrens1, H. K"ohncke1, T. Kr"umpel1, T. Peitzmann1, R. Santo1, and WA982 — 1Institut f"ur Kernphysik, Universit"at M"unster, D-48149 M"unster — 2
Inclusive photon spectra for 158 A GeV Pb+Pb reactions have been measured with the leadglass calorimeter LEDA of the WA98 experiment at the CERN SPS. The distinction of photons and charged particles in the leadglass detector by analyzing the different lateral widths of electromagnetic and hadronic showers becomes ambiguous at low transverse momenta. Therefore the photon spectrometer is supplemented by a charged particle veto detector (CPV) which makes it possible to determine photon transverse momentum spectra down to 30 MeV/c. An excess of the measured photons compared to the VENUS Monte-Carlo model is observed. As as possible source of “soft” photons hadronic bremsstrahlung radiation from charged hadrons produced during the collision has been studied in a model calculation.
* Partly supported by the German BMBF and the GSI.