Measuring centrality with slow protons in proton-nucleus collisions at 18 GeV/c

I. Chemakin, V. Cianciolo, B. A. Cole, R. Fernow, A. Frawley, M. Gilkes, S. Gushue, E. P. Hartouni, H. Hiejima, M. Justice, J. H. Kang, H. Kirk, N. Maeda, R. L. McGrath, S. Mioduszewski, D. Morrison, M. Moulson, M. N. Namboodiri, G. Rai, K. ReadL. Remsberg, M. Rosati, Y. Shin, R. A. Soltz, S. Sorensen, J. Thomas, Y. Torun, D. Winter, X. Yang, W. A. Zajc, Y. Zhang

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


Experiment E910 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 N grey and the mean number of interactions v(N grey) is studied using several simple models, one newly proposed, as well as the RQMD event generator. RQMD is shown to reproduce the N grey distribution, and exhibits a dependence of N grey on centrality that is similar to the behavior of the simple models. We find a strong linear dependence of N grey on v, with a constant of proportionality that varies with target. For the Au target, we report a relative systematic error for extracting v(N grey) that lies between 10 and 20% over all N grey.

Original languageEnglish
Article number024902
Pages (from-to)249021-2490212
Number of pages2241192
JournalPhysical Review C - Nuclear Physics
Issue number2
Publication statusPublished - 1999 Aug

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics


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