Dielectron cross-section measurements in nucleus-nucleus reactions at 1-A/GeV
/ Authors
R. Porter, S. Beedoe, R. Bossingham, M. Bougteb, W. Christie, J. Carroll, W. Gong, T. Hallman, L. Heilbronn, H. Huang
and 17 more authors
G. Igo, P. Kirk, G. Krebs, A. Letessier-Selvon, L. Madansky, F. Manso, H. Matis, Jeffrey Miller, C. Naudet, M. Prunet, G. Roche, L. Schroeder, P. Seidl, Zheng Wang, R. Welsh, W. Wilson, A. Yegneswaran
/ Abstract
We present measured dielectron production cross sections for Ca+Ca, C+C, He+Ca, and d+Ca reactions at 1.0 A GeV . Statistical uncertainties and systematic effects are smaller than in previous dilepton spectrometer (DLS) nucleus-nucleus data. For pair mass M{le}0.35 GeV/c{sup 2} we obtain (1) the Ca+Ca cross section is larger than the previous DLS measurement and current model results, (2) the mass spectra suggest large contributions from {pi}{sup 0} and {eta} Dalitz decays, and (3) d{sigma}/dM{proportional_to}A{sub P}A{sub T}. For M{gt}0.5 GeV/c{sup 2} the Ca+Ca to C+C cross section ratio is significantly larger than the ratio of A{sub P}A{sub T} values. {copyright} {ital 1997} {ital The American Physical Society}
Journal: Physical Review Letters