Systematic study of low-mass electron pair production in p-Be and p-Au collisions at 450 GeV/c
- Agakichiev, G
- Appenheimer, M
- Averbeck, R
- Ballester, F
- Baur, R
- Brenschede, A
- Diaz, J
- Drees, A
- Faschingbauer, U
- Ferrero, JL
- Fraenkel, Z
- Franke, M
- Fuchs, C
- Gatti, E
- Glassel, P
- Gunzel, T
- de los Heros, CP
- Hess, F
- Holzmann, R
- Iourevitch, V
- Irmscher, D
- Jacob, C
- Kuhn, W
- Lenkeit, B
- Löhner, H.
- Marin, A
- Marques, FM
- Martinez, G
- Metag, V
- Notheisen, M
- Novotny, R
- Olsen, LH
- Ostendorf, R
- Panebrattsev, Y
- Pfeiffer, A
- Ravinovich, I
- Rehak, P
- Sampietro, M
- Schon, A
- Schukraft, J
- Schutz, Y
- Shimansky, S
- Shor, A
- Simon, RS
- Specht, HJ
- Steiner, V
- Tapprogge, S
- Tel-Zur, G
- Tserruya, I
- Ullrich, T
- Wilschut, H.
- Wurm, JP
DOIAbstract
In a joint effort the CERES/NA45 and TAPS collaborations have measured low-mass electron pairs in p-Be and p-Au collisions at 450 GeV/c at the CERN SPS. In the range covered up to approximate to 1.5 GeV/c(2) the mass spectra from p-Be and p-Au collisions are well explained by electron pairs from decays of neutral mesons. For p-Au our result is new. For p-Be, the simultaneously measured electron pairs and photons served as a direct measure of the eta Dalitz decay contribution to the inclusive pair spectrum in which instrumental uncertainties are highly reduced. We confirm the earlier finding of HELIOS-1 with significantly reduced systematic uncertainties of 23% in the mass:range below 450 MeV/c(2), and of 28% in the mass range above 750 MeV/...