## Abstract

In a previous publication [T. Abbott et al., E802 Collaboration, Phys. Rev. C 63, 064602 (2001); 64, 029901(E) (2001)], measurements of the A dependence and pseudorapidity interval [Formula Presented] dependence of midrapidity [Formula Presented] distributions in a half-azimuth [Formula Presented] electromagnetic calorimeter were presented for [Formula Presented] [Formula Presented] O+Cu, Si+Au, and Au+Au collisions at the BNL-AGS. The validity of the “nuclear geometry” characterization versus [Formula Presented] was illustrated by plots of the [Formula Presented] distribution in each [Formula Presented] interval in units of the measured [Formula Presented] in the same [Formula Presented] interval for [Formula Presented] collisions. These plots, with aperture corrected scale in the physically meaningful units of number of average observed [Formula Presented] collisions, were nearly universal as a function of [Formula Presented] confirming that the reaction dynamics for [Formula Presented] production at midrapidity at AGS energies is governed by the number of projectile participants and can be well characterized by measurements in apertures as small as [Formula Presented] A key ingredient in these analyses is the probability [Formula Presented] for no signal to be detected in a given aperture [Formula Presented] for the fundamental [Formula Presented] collision. In fact the measured [Formula Presented] is biased and the true [Formula Presented] for the detector aperture is the measured value times [Formula Presented] The issues and merits of measuring the [Formula Presented] distribution in units of [Formula Presented] or [Formula Presented] in the same [Formula Presented] interval are presented and discussed. This method has application at RHIC, where p-[Formula Presented] data could be used as the reference distribution for two participants. The [Formula Presented] distributions for [Formula Presented] collisions, with [Formula Presented] scale normalized by [Formula Presented] in the same aperture for [Formula Presented] collisions, would then be given directly in the popular unit “per participant-pair” [K. Adcox et al., PHENIX Collaboration, Phys. Rev. Lett. 86, 3500 (2001); I. G. Bearden et al., BRAHMS Collaboration, Phys. Lett. B523, 227 (2001); B. B. Back et al., PHOBOS Collaboration, Phys. Rev. C 65, 031901(R) (2002); C. Adler et al., STAR Collaboration, Phys. Rev. Lett. 89, 202301 (2002)].

Original language | English |
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Journal | Physical Review C - Nuclear Physics |

Volume | 68 |

Issue number | 3 |

DOIs | |

Publication status | Published - 2003 |

## All Science Journal Classification (ASJC) codes

- Nuclear and High Energy Physics