학술논문
Measuring centrality with slow protons in proton-nucleus collisions at the AGS
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.
Source
Phys.Rev.C60:024902,1999
Subject
Language
Abstract
Experiment 910 has measured slow protons and deuterons from collisions of 18 GeV/c protons with Be, Cu, and Au targets at the BNL AGS. These correspond to the ``grey tracks'' first observed in emulsion experiments. We report on their momentum and angular distributions and investigate their use in measuring the centrality of a collision, as defined by the mean number of projectile-nucleon interactions. The relation between the measured Ngrey and the mean number of interactions, nu(Ngrey), is studied using several simple models, one newly proposed, as well as the RQMD event generator. RQMD is shown to reproduce the Ngrey distribution, and exhibits a dependence of Ngrey on centrality that is similar to the behavior of the simple models. We find a strong linear dependence of average Ngrey on nu, with a constant of proportionality that varies with target. For the Au target, we report a relative systematic error for extracting nu(Ngrey) that lies between 10% and 20% over all Ngrey.
Comment: 24 pages, 19 figures, submitted for publication to Phys. Rev. C, Formatted with RevTex Replacement: Fix typos, improve display figures, twocolumn format
Comment: 24 pages, 19 figures, submitted for publication to Phys. Rev. C, Formatted with RevTex Replacement: Fix typos, improve display figures, twocolumn format