Pion Decay Experiments

介子衰变实验

• 批准号: SAPPJ-2022-00025
• 负责人: Malbrunot, Chloé
• 金额: $ 5.39万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Project
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=764744
• 关键词: Pion; Decay; Experiments

Tensions between some flavor physics measurements and Standard Model predictions are accumulating. In particular some discrepancies hint at non-universality of lepton couplings and non-unitarity of the CKM quark mixing matrix which are triggering great interest in high precision measurements. A new experiment, PIONEER, is being developed to provide highly precise measurements which could shed new light on both lepton universality and CKM unitarity. PIONEER is aimed at studying the pienu branching ratio (pion decay to positron over pion decay to muon), pion beta decay and other rare reactions. It may be located at TRIUMF, Canada or at the Paul Scherer Institut (PSI), Switzerland. These facilities can provide intense low energy pion beams which can be stopped in a target for precise measurements of rare pion decays. Proposals have been (or are being) submitted to both laboratories. The newly formed PIONEER collaboration consists of experts from the PIENU experiment at TRIUMF, PEN at PSI, as well as international collaborators who have been involved in rare kaon decay and low energy stopped muon experiments, in the Fermilab Muon g-2 experimental campaign and ATLAS. This application seeks initial support for the Canadian PIONEER team consisting of four principal investigators from TRIUMF and UBC. The application focuses on developments related to a central element of the experiment: the calorimeter. Targeting an order of magnitude improvement in precision with respect to existing measurements of the pienu branching ratio and pion beta decay, the calorimeter has to fulfill stringent requirements in terms of energy resolution and pile-up suppression to cope with higher pion rates and enable unequaled suppression of systematic effects. A large liquid xenon detector instrumented with state-of-the-art vacuum ultraviolet sensors is the leading contender but advanced simulation studies and associated R&D have to be performed to determine the optimal configuration and to predict the overall performance of the detector. These issues are addressed in this proposal.

一些风味物理测量和标准模型预测之间的紧张关系正在积累。特别是一些差异暗示轻子耦合的非普适性和CKM夸克混合矩阵的非幺正性，这引发了人们对高精度测量的极大兴趣。一个新的实验，PIONEER，正在开发中，以提供高精度的测量，可以揭示轻子普适性和CKM幺正性的新的光。PIONEER旨在研究pienu分支比（π衰变到正电子或π衰变到μ子），π β衰变和其他罕见的反应。它可能位于加拿大的TRIUMF或瑞士的Paul谢勒研究所（PSI）。这些设备可以提供强烈的低能量的π介子束，可以停止在一个目标的精确测量罕见的π介子衰变。已经（或正在）向这两个实验室提交提案。新成立的PIONEER合作由来自TRIUMF的PIENU实验，PSI的PEN的专家组成，以及在费米实验室Muon g-2实验活动和ATLAS中参与罕见K介子衰变和低能停止μ介子实验的国际合作者。该申请寻求对加拿大PIONEER团队的初步支持，该团队由来自TRIUMF和UBC的四名主要研究人员组成。该应用程序的重点是与实验的核心元素相关的发展：量热计。针对一个数量级的改进精度相对于现有的测量pienu分支比和π β衰变，量热计必须满足严格的要求，在能量分辨率和堆积抑制，以科普更高的π速率，并使无与伦比的抑制系统的影响。配备最先进的真空紫外传感器的大型液体氙探测器是领先的竞争者，但必须进行先进的模拟研究和相关的研发，以确定最佳配置并预测探测器的整体性能。这些问题在本提案中得到了解决。