Precision measurements with trapped radioactive ions using the Canadian Penning Trap Mass spectrometer and associated ion traps at the Argonne National Laboratory

使用阿贡国家实验室的加拿大彭宁阱质谱仪和相关离子阱对捕获的放射性离子进行精确测量

• 批准号: SAPPJ-2018-00028
• 负责人: Sharma, Kumar
• 金额: $ 10.2万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Project
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=664899
• 关键词: Precision; measurements; trapped; radioactive; ions

The atomic masses of nuclides far from stability provide information on the energy released in the decay and nuclear reactions involving these exotic, short-lived, nuclei. The results are an important ingredient in predicting the rates and pathways of nuclear reactions that power explosive astrophysical events thought to be responsible for the nucleosynthesis of the heavier elements (through the rp-, nu-p- and r-processes). The data also provides a view of nuclear structure in regions where the nuclei have extreme neutron to proton ratios and, provide an opportunity for tests of nuclear physics theories trying to explain the properties of nuclei.***The Canadian Penning Trap Mass Spectrometer (CPT) is being used to measure the masses of very neutron-rich isotopes on or near the expected the reaction path for the astrophysical r-process. The nuclides of interest are produced by the CARIBU (Californium Radioactive Ion Beam Upgrade) facility at the Argonne Tandem Linear Accelerator System (ATLAS) by the spontaneous fission of the atoms in a ~1 Ci, 252Cf fission source. Improvements to the system have allowed us to perform measurements with an accuracy of (delta-m/m) of 10-7 among nuclides approaching 10-5% of the fission production. The implementation of a new phase-imaging measurement technique has allowed us to gain a dramatic increase in resolving power while reducing the observation time simultaneously, a significant improvement for measuring nuclides with short half-lives. Our measurements have focussed on nuclei that have been identified in astrophysical calculations as having the most effect on the calculated abundances in the rare earth peak. A new facility called the N = 126 factory is being developed that will give the CPT access to similar nuclei that are thought to contribute to the last abundance peak for the r-process.******In a second ion-trap system, the ions can be trapped in a gas-filled, cryogenic, open-geometry, radio-frequency quadrupole, ion trap (RFQ) providing a unique opportunity to study the correlation between the beta particles and the neutrinos emitted during the decay of the trapped ions. We have been studying the A=8 system with this apparatus in tests particle physics theories of the weak interaction. The trap can also be used to observe the emission of beta-delayed neutrons from fission fragments during their decay. A dedicated trap system is being constructed for the beta-delayed neutron work.******The amount requested will cover the operation and maintenance costs of the CPT mass spectrometer (which is entirely Canadian owned). The costs of the Canadian part of the team include the stipends for two graduate students, the salary for a post-doctoral fellow and, travel costs to and from the facility.

远离稳定性的核素原子质量提供了有关这些奇异的、短暂的原子核在衰变和核反应中释放的能量的信息。这些结果是预测核反应的速率和路径的重要组成部分，这些核反应为爆炸性天体物理事件提供动力，被认为是较重元素的核合成(通过rp-、nu-p-和r-过程)。这些数据还提供了原子核具有极端中子与质子比的区域的核结构视图，并为试图解释原子核性质的核物理理论测试提供了机会。*加拿大彭宁陷阱质谱仪(CPT)正被用于测量天体物理r过程预期反应路径上或附近的非常丰富的中子同位素的质量。感兴趣的核素是由Argonne串联式直线加速器系统(ATLAS)的Cariu(加利福尼亚放射性离子束升级)设施通过a~1Ci，252Cf裂变源中的原子自发裂变产生的。对该系统的改进使我们能够在接近裂变产物10-5%的核素中进行(增量-m/m)10-7的测量。一种新的相位成像测量技术的实施使我们能够在大大提高分辨率的同时减少观测时间，这对于测量半衰期较短的核素来说是一个重大的改进。我们的测量重点是在天体物理计算中被确定为对计算的稀土峰丰度影响最大的原子核。一种名为N=126工厂的新设备正在开发中，它将使CPT获得类似的原子核，这些原子核被认为对r过程的最后一个丰度峰有贡献。在第二个离子陷阱系统中，离子可以被捕获在充满气体的、低温的、开放几何结构的射频四极杆离子陷阱(RFQ)中，这为研究被捕获离子衰变过程中发出的β粒子和中微子之间的关联提供了一个独特的机会。在弱相互作用的粒子物理理论实验中，我们一直在用这个装置研究A=8系统。这种陷阱还可以用来观察裂变碎片在衰变过程中发出的贝塔延迟中子。正在为贝塔延迟中子工作建造一个专用的陷阱系统。*所要求的数额将包括CPT质谱仪(完全由加拿大所有)的操作和维护费用。团队的加拿大部分的费用包括两名研究生的津贴，一名博士后研究员的工资，以及往返该设施的旅费。