Relativistic Heavy Ion Collision Studies with the RHIC STAR Experiment

该项目的主要物理目标有两个方面：1）通过加热/压缩正常核物质到足够高的温度/密度，在实验室中创造一种称为“夸克物质”的新物质状态，同样重要的是，2）唯一地确定这种向夸克物质的转化是否真的发生了。夸克物质是由“自由”夸克和胶子组成的，这些基本粒子被束缚成质子和中子，构成正常的核物质。它预言宇宙在大爆炸后百万分之一秒完全处于夸克物质状态。我们制造夸克物质的方法将是使以接近光速运动的重核束（例如铅对铅和金对金）发生碰撞。这些束将由位于长岛布鲁克海文国家实验室和日内瓦的欧洲核子研究中心实验室的最先进的粒子加速器产生。为了确定夸克物质是否真的在这些高能重离子碰撞中产生，将出现大粒子探测器来探测产生的次级粒子（主要是π和K介子以及一系列更奇特的粒子）。理论预测，夸克物质形成的独特特征可以从这些次级粒子获得的信息中提取出来。俄亥俄州州立大学小组在这些实验中的主要作用之一是领导对来自一种新型粒子探测器的数据的分析，OSU参与开发了这种新型粒子探测器，称为“硅漂移探测器”，并希望提取独特的夸克物质签名。

The main physics goals of this project are two-fold: 1) to create in thelaboratory a new state of matter called "Quark Matter" by heating/compressing normal nuclear matter to a sufficiently high temperature/density, and, equally important, 2) to uniquely determine whether such atransformation to Quark Matter has actually taken place. Quark Matter iscomposed of "free" quarks and gluons, the fundamental particles whichare bound into protons and neutrons which make up normal nuclear matter. Itis predicted that the Universe was entirely in the Quark Matter stateseveral millionths of a second after the Big Bang. The method which we will useto make Quark Matter will be to collide beams of heavy nuclei (e.g. leadon lead and gold on gold) moving at speeds near the speed of light.These beams will be generated by new state-of-the-art particle acceleratorslocated at Brookhaven National Laboratory on Long Island and at the CERNlaboratory in Geneva. To determine whether Quark Matter has actuallybeen created in these high energy heavy ion collisions, large particledetectors will be present to detect the secondary particles which are produced(mostly pi and K mesons and a range of more exotic particles). Theoriespredict that unique signatures for Quark Matter formation can beextracted from information obtained from these secondary particles. One of themain roles of the Ohio State University group in these experiments is to leadthe analysis of the data from a new type of particle detector which OSUhas taken part in developing called a "Silicon Drift Detector" and,hopefully, to extract unique Quark Matter signatures.5