Hadron Blind Detector for Diagnostics of The Quark-Gluon Plasma at RHIC

用于诊断 RHIC 夸克-胶子等离子体的强子盲探测器

• 批准号: 0521536
• 负责人: Barbara Jacak
• 金额: $ 25万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-11-01 至 2007-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0521536&HistoricalAwards=false
• 关键词: Hadron; Blind; Detector; Diagnostics; Quark

During the first 10 microseconds following the Big Bang, the temperature of the universe was so high that ordinary hadrons such as protons and neutrons could not form. Instead, the dominantform of matter was unbound quarks and gluons in a state referred to as quark-gluon plasma. The extraordinarily high temperature of the epoch just after the Big Bang, approximately 2 x 10**12 K (200 MeV in energy units), is achievable today only via accelerator-based experiments colliding heavy nuclei at very high energy at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab. Analysis of available experimental data indicate that the energy density reached is more than 10**30 J/cm**3, exceeding that of ordinary nuclear matter by two orders of magnitude, and more than a factor of 10 above the threshold estimated for quark gluon plasma formation. However, there is as yet no experimental information whatsoever about the temperature reached by the plasma.Measuring the temperature requires detecting thermal radiation emitted by the plasma. This radiation consists of photons also pairs of electrons and positrons from decays of virtual photons.Unfortunately, enormous backgrounds from decays of the thousands of other particles formed in the collision have prevented reliable measurement of the thermal radiation to date. This proposal aims to solve this problem by acquisition of a detector using novel technology to directly measure and reject the otherwise overwhelming background of electrons and positrons from those decays. The energy distribution of the remaining electron-positron pairs reflects the temperature of the quark gluon plasma created at RHIC. Furthermore, good background rejection will allow a search for evidence of restoration of chiral symmetry. As the universe cooled down from the quark gluon plasma state, condensation of the quarks spontaneously broke the chiral symmetry present at high temperature. This step gave rise to the masses of the particles in normal matter, which are large compared to the masses of the light quarks inside the particles. Extensive theoretical study of chiral symmetry predicts that the symmetry should be restored at the high temperatures reached by RHIC and that the properties of particles can be significantly different. We will measure the decays of rho, omega and phi particles into electron-positron pairs and look for evidence of changes in their masses and widths.

在大爆炸之后的前10个微秒内，宇宙的温度太高，以至于普通的底发（如质子和中子）无法形成。取而代之的是，物质的主导形式是被称为夸克 - 格鲁恩等离子体的状态下的夸克和咕un。大爆炸之后，时代的高度高温，大约2 x 10 ** 12 k（能量单位的200 meV），只有通过基于加速器的实验才能在相对论重的重离子碰撞器（RHRIC）在Brookhaven National Lab的相对性重离子碰撞器（RHRIC）处于非常高的能量上的碰撞。对可用实验数据的分析表明，达到的能量密度大于10 ** 30 J/cm ** 3，超过了两个数量级的普通核物质，超过10倍以上的数限夸克Gluon等离子体形成的阈值。但是，目前尚无关于血浆达到温度的实验信息。测量温度需要检测血浆发出的热辐射。这种辐射由光子组成，还对虚拟光子的衰减成对。不幸的是，碰撞中成千上万个其他颗粒的衰减的巨大背景可以防止对迄今为止热辐射的可靠测量。该提案旨在通过使用新技术来获取探测器来直接测量和拒绝这些衰减中电子和正面的压倒性背景来解决此问题。其余电子词素对的能量分布反映了RHIC产生的夸克gluon等离子体的温度。此外，良好的背景拒绝将允许搜索恢复手性对称性的证据。当宇宙从夸克gluon血浆状态冷却时，夸克的凝结自发地打破了高温下存在的手性对称性。此步骤产生了正常物质中颗粒的质量，与颗粒内的光夸克的质量相比，它们很大。手性对称性的广泛理论研究预测，在RHIC达到的高温下应恢复对称性，并且颗粒的性质可能显着差异。我们将将Rho，Omega和Phi颗粒的衰变评估为电子峰值对，并寻找其质量和宽度变化的证据。