Relativistic Heavy-Ion Physics at the University of Rochester

这笔赠款为罗切斯特大学物理和天文学系的相对论重离子小组提供了运作资金。 在这一年中，我们将完成对2001年和2003年在布鲁克海文国家实验室（BNL）的相对论重离子对撞机（RHIC）上使用PHOBOS探测器收集的数据的分析，并考虑PHOBOS探测器可能的升级方案。 PHOBOS是四个实验之一，旨在观察在RHIC中原子核碰撞时产生的极端能量密度。 人们相信，一种新的物质状态，即所谓的夸克胶子等离子体（QGP），将在这些碰撞中形成。 PHOBOS正在寻找这种新的物质状态，它的性质将提供有关极早期宇宙（大爆炸后几微秒）状态的重要和新的信息。 PHOBOS旨在以无偏的方式研究尽可能多的碰撞，并寻找p+p，p+A和A+A碰撞之间的显着差异。 收集的数据包括2001年Au+Au碰撞、2003年d+Au碰撞以及2001年和2003年p+p碰撞的研究。 预计QGP只会在Au+Au碰撞中形成，而对d+Au和p+p的研究是用来从Au+Au碰撞收集的数据中减去“正常”核子-核子物理的贡献。 由罗切斯特小组设计和建造的飞行时间阵列大大增强了PHOBOS的物理能力，使其粒子识别能力增加了一倍。 对于2003年的运行，我们增加了我们的阵列的飞行路径，允许使用识别粒子高达约4 - 5 GeV/c的动量。 2001年数据的分析已基本完成，2003年数据的分析才刚刚开始。

This grant provides operating funds for the relativistic heavy-ion group at the Department of Physics and Astronomy at the University of Rochester. During the year covered by this grant we will complete the analysis of the data collected in 2001 and 2003 with the PHOBOS detector at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) and consider possible upgrade options for the PHOBOS detector. PHOBOS is one of the four experiments looking at the extreme energy densities that are created when nuclei collide at RHIC. It is believed that a new state of matter, the so-called quark-gluon plasma (QGP), will be formed in these collisions. PHOBOS is looking for this new state of matter, and its properties will provide important and new information about the state of the very early universe (a few microseconds after the Big Bang). PHOBOS was designed to study as many collisions as possible, in an unbiased way, and to search for significant differences between p+p, p+A, and A+A collisions. The data collected sofar inlcudes studies of Au+Au collisions in 2001, d+Au in 2003, and p+p in 2001 and 2003. It is expected that the QGP will only be formed in the Au+Au collisions, and the studies of d+Au and p+p are used to subtract the contribution of "normal" nucleon-nucleon physics from the data collected in Au+Au collisions. The time-of-flight array, designed and constructed by the Rochester group, significantly enhances the physics capabilities of PHOBOS, by roughly doubling its particle identification capabilities. For the 2003 run we have increased the flight path of our arrays, allowing use to identify particles up to momenta of around 4 - 5 GeV/c. The analysis of the 2001 data is almost completed, and the analysis of the 2003 data is just getting started.