Measurement of QEC by Penning-Trap Mass Spectrometry

通过 Penning-Trap 质谱法测量 QEC

• 批准号: 272258025
• 负责人: Professor Dr. Klaus Blaum
• 金额: --
• 依托单位: Max-Planck-Institut für Kernphysik
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/272258025?language=en
• 关键词: Measurement; QEC; Penning; Trap; Mass

Within the framework of the second phase of the ECHo project (ECHo-100k) the team of the PI has the goal to provide the ECHo experiment with an independently and directly measured Q-value of the electron capture (EC) in 163Ho with an uncertainty of a few eV. The tool to be used to reach this goal is the high-precision Penning-trap mass spectrometer PENTATRAP, which is located at the MPIK and is presently in the commissioning phase. An accomplishment of the ultimate goal depends on the successful realization of two main subprojects: The first subproject encompasses a development of a stable and reliable source of highly charged 163Ho ions. Since the sample contains just a few nanograms of 163Ho and a production rate of a few ten ions per second is needed, the source will be optimised with stable 165Ho. For this, a dedicated test setup is being under development. It is composed of an electron beam ion trap (EBIT), a 90° magnetic separator and a diagnostic station. In the EBIT various ion production techniques will be extensively investigated in order to find the one which would suit our demands best. A 90° magnetic separator with a mass-to-charge resolving power of about 400 will be placed after the EBIT to select a certain charge state of the ions which will then be sent to a diagnostic station consisting of a microchannel plate (MCP) with a phosphor screen. The results obtained with the test setup will allow us to build an ion source which will provide the Penning-trap mass spectrometer PENTATRAP with a sufficiently large number of highly charged ions of 163Ho. The second subproject consists of the commissioning of the Penning-trap mass spectrometer PENTATRAP. The mass spectrometer has been designed to measure mass ratios of highly charged ions with a relative uncertainty of 10E-11. It employs five Penning traps situated inside the cold bore of a 7T magnet and a dedicated detection system for image charge detection. The commissioning implies, first, a successful transport of various ions from an ion source to the mass spectrometer with successive trapping of the ions in a chosen charge state in any of the five traps for at least several hours. Second, the trapped ions must be prepared for measurements by cooling their trap motions by means of resistive ion cooling. Third, the traps must be optimized with reference ions, e.g., highly charged ions of argon. Fourth, the ability to determine the cyclotron frequency of the reference ions with a needed relative uncertainty of at most 10E-11 must be demonstrated with different phase resolving detection techniques. Finally, the mass ratio of two species with well-known masses, e.g. 187Re and 187Os, must be determined correctly with a relative uncertainty of about 10E-11. A successful realization of these subprojects will enable us to address our ultimate goal – the determination of the Q-value of the EC in 163Ho with an uncertainty of a few eV.

在ECHo项目第二阶段（ECHo-100 k）的框架内，PI团队的目标是为ECHo实验提供独立且直接测量的163 Ho中电子捕获（EC）的Q值，其不确定性为几eV。用于实现这一目标的工具是高精度彭宁阱质谱仪PENTATRAP，该仪器位于MPIK，目前处于调试阶段。最终目标的实现取决于两个主要子项目的成功实现：第一个子项目包括开发稳定可靠的高电荷163 Ho离子源。由于样品仅含有几纳克的163 Ho，并且需要每秒几十个离子的产生速率，因此将使用稳定的165 Ho优化源。为此，正在开发一个专门的测试装置。它由电子束离子阱（EBIT）、90°磁分离器和诊断站组成。在EBIT中，将广泛研究各种离子生产技术，以找到最适合我们需求的技术。将在EBIT之后放置质荷分辨能力约为400的90°磁分离器，以选择离子的特定电荷状态，然后将其发送到由具有荧光屏的微通道板（MCP）组成的诊断站。与测试设置所获得的结果将使我们能够建立一个离子源，这将提供潘宁阱质谱仪PENTATRAP与足够大量的高电荷离子的163 Ho。第二个分项目包括启用彭宁阱质谱仪PENTATRAP。质谱仪的设计是为了测量高电荷离子的质量比，相对不确定度为10 E-11。它采用了位于7 T磁体的冷孔内的五个潘宁陷阱和用于图像电荷检测的专用检测系统。调试意味着，首先，各种离子从离子源到质谱仪的成功传输，在五个阱中的任何一个中连续捕获处于选定电荷状态的离子至少几个小时。第二，被捕获的离子必须准备测量，通过冷却它们的陷阱运动的电阻离子冷却。第三，必须用参考离子优化阱，例如，高度带电的氩离子。第四，必须用不同的相位分辨检测技术证明以所需的至多10 E-11的相对不确定度确定参考离子的回旋频率的能力。最后，两个已知质量的物质，例如187 Re和187 Os的质量比必须正确确定，相对不确定度约为10 E-11。这些子项目的成功实现将使我们能够解决我们的最终目标-在几个电子伏特的不确定性的163 Ho的EC的Q值的测定。