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北美退伍军人节(Veterans Day),12 日无更新
arXiv 2004.10520physics.ins-dethep-ex
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LHC运行3的ALICE时间投影室升级

Upgrade of the ALICE Time Projection Chamber for the LHC Run 3

Adam Laszlo Gera

摘要:

大型强子对撞机(CERN)的实验之一ALICE正在进行第二次长时间关闭(LS 2)期间进行雄心勃勃的升级。这个项目的主要目标是访问罕见的事件和以前无法访问的物理观测。增加的Pb-Pb和pp碰撞率需要在LHC的下一个运行3中相应地更高的TPC操作率。到目前为止使用的操作门控MWPC读出不能以如此快的速率使用。因此,需要一种新的读出室,采用新技术,并且在动量和能量分辨率上没有任何妥协。作为解决方案,应用了气体电子倍增器(GEM)技术。这种新的读出室由内(IROC)和外(OROC)读出室组成,具有4级GEM级联,以减少后漂移离子空间电荷。这些四重堆叠已被证明提供足够的离子阻挡能力。这种结构还保持了固有能量分辨率,并将空间电荷失真保持在可容忍的水平。GEM在运行过程中无法修复,因此为了尽量减少不合适的箔片,开发了质量保证体系。这些洁净室测量研究孔尺寸均匀性、增益均匀性和电稳定性。由于连续读出,更高的读出速率是可能的。新的ASIC-SAMPA就是为此而开发的。在ROC组装之后,一些腔室在ALICE洞穴中进行了测试,并在CERN的GIF开始了对ROC主体的进一步测试。

英文摘要:

ALICE, one of the experiments at the Large Hadron Collider (CERN), is undergoing ambitious upgrades during the ongoing second long shutdown (LS2). The main goal of this project is to access rare events and previously inaccessible physics observables. The increased Pb-Pb and pp collision rates need a correspondingly higher TPC operation rate in the next Run 3 of the LHC. The operational gated MWPC readout used so far cannot be used at such fast rates. Therefore a new readout chamber is needed with a novel technology and without any compromise on the momentum and energy resolution. As a solution the Gas Electron Multiplier (GEM) technology is applied. This new readout chamber consists of inner-(IROC) and outer (OROC) readout chambers with a 4 stage GEM cascade in order to reduce back-drifting ion space charges. These quadruple stacks have proven to provide sufficient ion blocking capabilities. This structure also preserves the intrinsic energy resolution and keeps the space-charge distortions at a tolerable level. The GEMs cannot be repaired during operation, therefore to minimize the unsuitable foils, the Quality Assurance system is developed. These cleanroom measurements investigate the hole size uniformity, the gain uniformity and the electrical stability. Due to the continuous readout, higher readout rate is possible. The new ASIC-SAMPA has been developed for this purpose. After the ROC assembly some of chambers were tested in the ALICE cavern, and a test campaign started for the further testing of the ROC bodies at GIF at CERN.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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