학술논문
Centrality dependence of Pi- Production and Stopping in p-A Collisions at 18 GeV/c
Document Type
Working Paper
Author
Chemakin, I.; Cianciolo, V.; Cole, B. A.; Fernow, R.; Frawley, A.; Gilkes, M.; Gushue, S.; Hartouni, E. P.; Hiejima, H.; Justice, M.; Kang, J. H.; Kirk, H.; Maeda, N.; Mioduszewski, S.; Morrison, D.; Moulson, M.; Namboodiri, M. N.; Rai, G.; Read, K.; Remsberg, L.; Rosati, M.; Shin, Y.; Soltz, R. A.; Sorensen, S.; Thomas, J.; Torun, Y.; Winter, D.; Yang, X.; Zajc, W. A.; Zhang, Y.
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Subject
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Abstract
First results are presented from BNL experiment E910 on pion production and stopping in proton-Be, Cu, and Au collisions at a beam momentum of 18 GeV/c. We characterize the centrality of the collisions using the measured number of "grey" tracks, Ngrey,and a derived quantity, nu, the number of inelastic nucleon-nucleon scatterings suffered by the projectile during the collision. We find that for the three targets the average backward rapidity shift of the leading proton follows a common trend versus nu with the projectile losing, on average, 2 units of rapidity in the first 2-3 scatterings. The average rapidity shift increases more slowly with subsequent scatterings reaching a maximum of 2.5 units. The pi- multiplicity measured within the E910 acceptance saturates with increasing nu in p-Au collisions while the pi- multiplicity in p-Be collisions increases faster with nu than expected from the wounded-nucleon model. Comparisons of our data with the RQMD cascade model suggest that in very central p-Au collisions most of the pions are produced near zero rapidity in the lab.
Comment: 5 pages, 13 figures, submitted for publication to Phys. Rev. Lett., Formatted with RevTex
Comment: 5 pages, 13 figures, submitted for publication to Phys. Rev. Lett., Formatted with RevTex