Frontier Neutrino Physics: Ba ion tagging

中微子物理前沿：Ba 离子标记

• 批准号: SAPPJ-2019-00058
• 负责人: Gornea, Razvan
• 金额: $ 14.24万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Project
• 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=718954
• 关键词: Frontier; Neutrino; Physics; Ba; ion

Neutrino oscillation experiments have demonstrated that neutrinos are massive but their absolute scale cannot be established from such measurements. Neutrinoless double beta decay (0nbb) experiments are able to probe whether neutrinos are Majorana particles, help determine the neutrino mass spectrum and explore physics beyond the Standard Model. The observation of this lepton number violating process will demonstrate the existence of a new mass generation mechanism unrelated to the Higgs field and shed light on the primordial physics responsible for the matter dominated universe that we are witnessing. The next-generation 0nbb experiments require tonne-scale active mass and extreme low background. The nEXO collaboration is proposing a 5-tonne liquid xenon (LXe) time projection chamber with sufficient sensitivity to the half-life of Xe-136 0nbb decay to be able to explore the inverted mass hierarchy region of the parameter space. To go further and reach the ultimate sensitivity to the normal hierarchy, we propose to explore a sophisticated technique for background rejection which calls for the detection of the single Ba ion produced uniquely by the double beta decay of Xe-136. Previous 0nbb searches have been background limited. With Ba ion tagging, the residual radioactive background can be completely rejected. Events from the high energy tail of the allowed 2nbb decay can only be mitigated by excellent detector energy resolution. The nEXO collaboration conducts an intense R demonstrate efficient ion collection from LXe using radioactive ions [at Carleton university] demonstrate efficient ion extraction to a low-pressure analysis chamber using a RF ion funnel and a multi-reflection time-of-flight mass spectrometer [at McGill university] design, optimize and construct a high signal-to-noise ratio linear Paul trap with ion cooling and bunching capabilities [at TRIUMF] demonstrate optical discrimination of the Ba-136 ion against other natural occurring barium isotopes [at Carleton university] The refinement of the Ba ion tagging technique remains very challenging but the method provides a unique opportunity to fully eliminate the residual radioactive backgrounds and it will allow a future tonne-scale experiment to scan all the relevant parameter space associated with the normal mass hierarchy. Given the interdisciplinary nature of the program, we expect to attract many graduate students and provide great opportunities for training technicians and post-doctoral fellows.

中微子振荡实验已证明中微子质量很大，但无法通过此类测量确定中微子的绝对规模。无中微子双β衰变（0nbb）实验能够探测中微子是否是马约拉纳粒子，帮助确定中微子质谱并探索标准模型之外的物理现象。对这种违反轻子数过程的观察将证明存在一种与希格斯场无关的新质量生成机制，并揭示了我们所目睹的物质主导宇宙的原始物理学。 下一代 0nbb 实验需要吨级活性质量和极低背景。 nEXO 合作提出了一个 5 吨液氙 (LXe) 时间投影室，该室对 Xe-136 0nbb 衰变的半衰期具有足够的灵敏度，能够探索参数空间的倒置质量层次区域。为了进一步达到对正常层次结构的最终灵敏度，我们建议探索一种复杂的背景抑制技术，该技术需要检测由 Xe-136 的双 β 衰变独特产生的单个 Ba 离子。 之前的 0nbb 搜索受到背景限制。通过Ba离子标记，可以完全去除残留的放射性背景。来自允许的 2nbb 衰变的高能尾部的事件只能通过出色的探测器能量分辨率来缓解。 nEXO 合作进行了一次激烈的 R 演示，使用放射性离子从 LXe 中高效收集离子 [在卡尔顿大学] 展示使用射频离子漏斗和多重反射飞行时间质谱仪将离子有效提取到低压分析室[麦吉尔大学] 设计、优化和构建具有离子冷却和聚束功能的高信噪比线性保罗陷阱 [TRIUMF] 证明 Ba-136 离子与其他天然存在的钡同位素的光学区别[在卡尔顿大学] Ba 离子标记技术的完善仍然非常具有挑战性，但该方法提供了一个独特的机会来完全消除残留的放射性背景，并且它将允许未来的吨级实验扫描与正常质量等级相关的所有相关参数空间。鉴于该项目的跨学科性质，我们希望吸引许多研究生，并为培训技术人员和博士后提供良好的机会。