The Belle-II Electromagnetic Calorimeter Endcap

Belle-II 电磁热量计端盖

• 批准号: SAPEQ-2014-00009
• 负责人: Roney, Michael
• 金额: $ 8.01万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Research Tools and Instruments
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567993
• 关键词: Belle; II; Electromagnetic; Calorimeter; Endcap

Belle-II will probe the flavour sector of particle physics at the high-luminosity SuperKEKB e+e- collider, located at the KEK laboratory in Japan. Physics operations will start in late 2016, with the goal of collecting by 2022 thirty times the combined integrated luminosity of the two previous generation B-factories, PEP-II at SLAC and KEKB at KEK. This precision-frontier facility will open an exciting window on new energy scales beyond the reach of existing colliders, including the LHC, by virtue of quantum loop corrections that are sensitive to massive, and as yet undiscovered, particles. These hypothesized particles manifest themselves in precision measurements of processes involving bottom and charm quarks and tau leptons, such as CP violation and other asymmetries, rare decays, and processes that are forbidden within our current understanding of physics. This program is complementary to direct searches for new physics at the LHC. The funds requested will enable the Canadian group to finalize the research needed for the group's detector hardware contribution, and to develop the tools and expertise for the full hardware contribution. Belle-II will start data taking with the thallium-doped cesium iodide (CsI(Tl)) scintillator calorimeter from Belle, outfitted with new digitizing and feature-extraction electronics. This calorimeter had very good performance, but has a slow scintillation time constant (1 microsecond). At the increased luminosity of SuperKEKB, high occupancies from beam related backgrounds will cause significant deterioration of the performance of the forward endcap calorimeter. As its contribution to the Belle-II detector, the Canadian group is proposing to upgrade the high-occupancy regions of the forward endcap to pure CsI. Pure CsI is much faster than CsI(Tl), and is therefore much less sensitive to backgrounds. However, it has a much lower light yield. To deal with the characteristics of fast pulses, low light yield and large dynamic range, the CsI crystals will use different photosensors, amplifiers, digitizers, and feature-extraction algorithms than the existing calorimeter. The Canadian group will take responsibility for all aspects of this project, including procuring the crystals and photomultiplier tubes; developing and building the amplifiers, digitizing, and feature-extraction electronics; calibration systems and procedures; and modifications to the mechanical and cooling systems. We are requesting funds to develop and test a 25-crystal array together with the associated photosensors and electronics, approximately 8% of the full project. This will allow us to complete the R&D on the readout system, and verify that our proposed solutions satisfy the requirements at a system level in a test beam environment. It will also allow us to develop the crystal and phototube procurement protocols, including the equipment and tooling needed to verify the specifications. Understanding the beam-related backgrounds is an essential component of the project. Belle-II is developing a set of detectors to be installed in January 2015, which will quantify the backgrounds during the commissioning of SuperKEKB and enable comparisons to simulations. We have proposed to the collaboration that this set should include thermal neutron detectors, since this background component determines the lifetime of the existing calorimeter readout electronics, as well as that of other Belle-II detector systems, and is responsible for a noticeable component of the calorimeter occupancy. It is also the most difficult component to simulate accurately. We are requesting funds for He-3 neutron counters to undertake this measurement.

Belle-II将在位于日本KEK实验室的高亮度SuperKEKB e+e对撞机上探测粒子物理学的味道部分。物理操作将于2016年底开始，目标是到2022年收集前两代B工厂（SLAC的PEP-II和KEK的KEKB）合并的30倍综合光度。这个精确前沿的设施将打开一个令人兴奋的窗口，在新的能量尺度超出现有的对撞机，包括大型强子对撞机，凭借量子回路校正是敏感的大规模，尚未发现，粒子。这些假设的粒子在涉及底夸克、粲夸克和τ轻子的过程的精确测量中表现出来，例如CP破坏和其他不对称性、罕见的衰变以及我们目前对物理学的理解所禁止的过程。该计划是对LHC直接寻找新物理的补充。 所要求的资金将使加拿大小组能够最后完成该小组提供探测器硬件所需的研究，并开发提供全部硬件所需的工具和专门知识。 Belle-II将开始使用贝儿的掺铊碘化铯（CsI（Tl））闪烁体量热计进行数据采集，该量热计配备了新的数字化和特征提取电子设备。这种量热计具有非常好的性能，但具有慢的闪烁时间常数（1微秒）。在SuperKEKB的亮度增加时，来自束流相关背景的高占用率将导致前向端盖量能器性能的显著恶化。作为对Belle-II探测器的贡献，加拿大小组建议将前端盖的高占用区升级为纯CsI。纯CsI比CsI（Tl）快得多，因此对背景的敏感性低得多。然而，它的光输出要低得多。为了应对快脉冲、低光产额和大动态范围的特征，CsI晶体将使用与现有量热计不同的光传感器、放大器、数字化器和特征提取算法。 加拿大小组将负责该项目的所有方面，包括采购晶体和光电倍增管;开发和制造放大器、数字化和特征提取电子设备;校准系统和程序;以及修改机械和冷却系统。 我们正在申请资金，以开发和测试25个晶体阵列以及相关的光电传感器和电子设备，约占整个项目的8%。这将使我们能够完成读出系统的研发，并验证我们提出的解决方案在测试束环境中满足系统级的要求。它还将使我们能够制定晶体和光电管采购协议，包括验证规格所需的设备和工具。 了解光束相关背景是该项目的重要组成部分。Belle-II正在开发一套将于2015年1月安装的探测器，该探测器将在SuperKEKB调试期间对背景进行量化，并能够与模拟进行比较。我们建议合作，这套应该包括热中子探测器，因为这个背景组件决定了现有的量热计读出电子设备的寿命，以及其他Belle-II探测器系统的寿命，并负责量热计占用的一个明显的组成部分。它也是最难精确模拟的部件。我们正在申请资金，用于He-3中子计数器进行这项测量。