A multi-purpose particle detector for measurement of decays of highly-charged ions in storage rings

用于测量存储环中高电荷离子衰变的多用途粒子探测器

• 批准号: SAPEQ-2020-00004
• 负责人: Dillmann, Iris
• 金额: $ 10.91万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Research Tools and Instruments
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=718758
• 关键词: multi; purpose; particle; detector; measurement

The measurement of decay properties of ions orbiting in a storage ring is a complementary path to conventional measurement techniques. It has been proven to be a very successful tool for the simultaneous mass measurement of dozens of ions injected in the storage ring. Also exotic decay modes of ions with only a few or no electrons, so-called "highly-charged ions" (HCI) have been discovered and measured for the first time in storage rings. Examples are the "bound-state beta decay" that leads to an acceleration of the decay of some nuclei in the fully ionized state, e.g. 187Re(75+) decayed 1 billion times faster than in the neutral state, and stable neutral 163Dy becomes radioactive and decays with a half-life of 45 days when transferred into the fully-ionized 66+ charge state. It is a modern nuclear physicists dream to be able to "manipulate" how fast material can decay. Nuclear transmutation, the transformation of long-lived radioactive waste into something that decays faster, could greatly benefit from these studies- however the strong acceleration of decay modes has so far only been observed for a few cases that are not the main contributors of radioactive waste. For the measurements in the storage rings two types of detectors are needed: one for the destruction-free detection and identification of the ions while they orbit in the storage ring, and one detector for the detection of the decay products if they cannot be stored in the storage ring due to its limited momentum acceptance. For the destruction-free identification of the ions and respective mass measurement a device called "Schottky pickups" is used. For the detection of decay products that leave the acceptance of the ring particle detector telecopes are used. The foundation for this proposal has been laid by my Helmholtz Young Investigators Research Group in 2010-15. In collaboration with the TU Munich my group has constructed the prototype detector "CsISiPHOS" (CsI-Silicon Particle detector for Heavy ions Orbiting in Storage rings) and tested and commissioned it with beam in 2015. CsISiPHOS is a multi-purpose detector that has been built to detect various particles emitted in decay processes in the Experimental Storage Ring (ESR) and/or Collector Ring (CR) and is an integral part of the ILIMA (Investigation of LIfetimes and MAsses) program at FAIR. The detector has to provide a position resolution corresonding to the beam diameter in the ring after cooling, as well as unique particle identification in mass A and nuclear charge Z to allow a clear separation of isobaric contaminants. Several improvements have been suggested for the upgraded version of this detector which have been described in the TDR that has been submitted to the FAIR ECE council in 2017/18. If funded, this new detector and the new data aquisition system will be used in upcoming FAIR Phase-0 experiments starting in summer 2021.

测量存储环中绕轨道运行的离子的衰变特性是传统测量技术的补充途径。它已被证明是一种非常成功的工具，可以同时测量存储环中注入的数十种离子的质量。此外，还首次在存储环中发现并测量了只有少数电子或没有电子的离子的奇特衰变模式，即所谓的“高电荷离子”(HCI)。例子是“束缚态β衰变”，它会导致一些处于完全电离状态的原子核加速衰变，例如187Re(75+) 的衰变速度比中性态快 10 亿倍，而稳定的中性 163Dy 在转变为完全电离的 66+ 电荷态时变得具有放射性并衰变，半衰期为 45 天。 现代核物理学家的梦想是能够“操纵”材料衰变的速度。核嬗变，即长寿命放射性废物转变为衰变速度更快的物质，可以从这些研究中受益匪浅——然而，迄今为止，仅在少数情况下观察到衰变模式的强烈加速，而这些情况并非放射性废物的主要贡献者。 对于存储环中的测量，需要两种类型的检测器：一种用于在存储环中绕轨道运行时对离子进行无破坏的检测和识别，另一种检测器用于检测衰变产物（如果衰变产物由于其动量接受能力有限而无法存储在存储环中）。为了无损地识别离子并进行相应的质量测量，使用了一种称为“肖特基拾音器”的设备。为了检测离开环形粒子探测器验收的衰变产物，使用了望远镜。 我的亥姆霍兹青年研究者研究小组在 2010-15 年为这项提案奠定了基础。我的小组与慕尼黑工业大学合作，建造了原型探测器“CsISiPHOS”（用于存储环中重离子轨道的 CsI 硅粒子探测器），并于 2015 年用光束对其进行了测试和调试。CsISiPHOS 是一种多用途探测器，用于检测实验存储环 (ESR) 和/或收集环 (CR) 中衰变过程中发射的各种粒子，并且是一种 FAIR 的 ILIMA（生命周期和质量调查）计划的组成部分。探测器必须提供与冷却后环中光束直径相对应的位置分辨率，以及质量 A 和核电荷 Z 中的独特粒子识别，以实现同量异位污染物的清晰分离。 针对该探测器的升级版本提出了多项改进建议，这些改进已在 2017/18 年提交给 FAIR ECE 理事会的 TDR 中进行了描述。如果获得资助，这款新探测器和新数据采集系统将用于 2021 年夏季开始的 FAIR Phase-0 实验。