Ultra-relativistic heavy ion collisions - Application for bridging support

超相对论重离子碰撞-桥接支撑应用

基本信息

批准号：
PP/F001061/1
负责人：
Peter Jones
金额：
$ 48.54万
依托单位：
University of Birmingham
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=PP%2FF001061%2F1
关键词：
Ultra relativistic heavy ion collisions

项目摘要

Most of the visible mass of the universe is in the form of protons and neutrons that make up the everday nuclei found within the elements we see around us. This might suggest that protons and neutrons are the fundamental building blocks of matter, but, in fact, protons and neutrons are themselves composed of more fundamental particles known as quarks. Quarks are strongly attracted to each other and are never seen in isolation. They owe their attraction to gluons, which are force particles that stick quarks together. What makes this attraction different from other types of forces is that the gluons attract each other too. It is this interaction amongst the force particles that makes the nuclear force so strong. It also has a rather surprising effect: the strength of the interaction decreases with distance. This suggests that at high enough densities quarks and gluons behave as if they are free particles. In this case protons and neutrons would not exist at all. Instead matter would be comprised of a plasma of quarks and gluons. This would have been what matter was like during the first fraction of a second after the Big Bang. Attempts are now underway to recreate the conditions of the Big Bang in the laboratory, albeit on a much smaller scale, by colliding heavy nuclei at very high energies. In a head-on collision between two nuclei a significant amount of kinetic energy is converted into new particles, producing matter which is both extremely dense and extremely hot. What is needed is an experimental probe that can tell us exactly how dense and how hot it really is. One way to do this is to study jets. Jets occur when quarks and gluons collide head-on and are scattered sideways. As free quarks and gluons are not observed, they shower into a jet of hadrons. This is a rare process, but sufficient numbers are produced to make them a powerful diagnostic tool. The key to their usefulness lies in the fact that they can be absorbed in the hot dense medium that is the quark-gluon plasma, making them an ideal tool for studying the properties of this new state of matter. This proposal seeks to unite two experimental groups at Birmingham University to study jets, amongst other observables, in heavy-ion collisions at the Large Hadron Collider (LHC), which is situtated at the European Centre for Nuclear Research (CERN) in Switzerland. The LHC will start colliding protons in late 2007 and the first heavy-ion beams are expected at the end of 2008. Compared to previous studies at the Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC), near New York, the LHC will achieve collision energies 30 times higher than seen before. It is expected that the initial temperature will be 4-5 times higher than the critical temperature required to observe a transition to quark deconfined matter. One of the groups at Birmingham is already heavily involved in preparations for the first collisions to be seen in the ALICE experiment. The other group has been involved in an experiment called STAR at the RHIC facility and bring with them experience of data analysis using a similar detector system. Together, it is hoped that the two groups will make a major impact on an international quest to discover what matter was like a fraction of a second after the Big Bang.

宇宙的大多数可见质量都是质子和中子的形式，这些质子和中子构成了我们周围所见的元素中至上的核。这可能表明质子和中子是物质的基本基础，但实际上，质子和中子本身是由称为夸克的更基本的颗粒组成的。夸克彼此强烈吸引，从未孤立地看到。他们的吸引力归功于胶子，这些振荡是将夸克粘在一起的力颗粒。使这种吸引力不同于其他类型的力量的原因是，振荡也相互吸引。力颗粒之间的这种相互作用使核力如此强大。它也具有相当令人惊讶的效果：相互作用的强度随距离而降低。这表明，在足够高的密度下，夸克和胶子的行为就像是自由颗粒一样。在这种情况下，质子和中子根本不存在。取而代之的是，物质将由夸克和胶子的等离子体组成。在大爆炸之后的第一秒钟，这就是重要的。现在正在尝试通过在极高的能量上碰撞沉重的核，重新创建实验室中的大爆炸状况，尽管规模较小。在两个核之间正面的碰撞中，大量的动能被转化为新颗粒，产生的物质既密集又非常热。需要的是一个实验探测器，它可以准确地告诉我们它的真正密度和真实程度。一种方法是研究喷气机。当夸克和弹力正面碰撞并侧面散落时，会发生喷气机。由于未观察到自由夸克和脾气，它们会淋到一架Hadrons中。这是一个罕见的过程，但是产生了足够的数字以使其成为强大的诊断工具。它们有用性的关键在于，它们可以在夸克 - 葡萄糖等离子体的热致密介质中吸收，这使它们成为研究这种新物质状态的理想工具。该提案旨在在伯明翰大学团结两个实验组，以研究喷气机，以及其他可观察的人，在大型强子对撞机（LHC）的重离子碰撞中，该碰撞位于瑞士的欧洲核研究中心（CERN）。 LHC将于2007年底开始碰撞质子，并预计在2008年底将在2008年底进行重型离子束。与以前在纽约附近的Brookhaven National Laboratory的相对论重离子对撞机（RHRIC）进行的研究相比，LHC将实现比以前30倍的碰撞能量。预计初始温度将比观察到夸克脱合物的过渡所需的临界温度高4-5倍。伯明翰的一个群体已经很大程度上参与了在爱丽丝实验中看到的第一次碰撞的准备。另一组参与了RHIC设施中名为Star的实验，并使用类似的检测器系统带来了数据分析的经验。希望这两个小组能对国际追求产生重大影响，以发现大爆炸之后的一秒钟，这是一秒钟的重要性。