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.

远不稳定的核素的原子质量提供了衰变和涉及这些奇特的、寿命短的原子核的核反应中释放能量的信息。这些结果是预测核反应速率和途径的重要组成部分，核反应为爆炸天体物理事件提供动力，这些事件被认为是导致重元素核合成（通过rp-， nu-p-和r-过程）的原因。这些数据还提供了对原子核具有极端中子质子比区域的核结构的看法，并为试图解释原子核性质的核物理理论的测试提供了机会。***加拿大Penning陷阱质谱仪（CPT）被用来测量在天体物理r过程的预期反应路径上或附近的非常富含中子的同位素的质量。所研究的核素是由阿贡串联直线加速器系统（ATLAS）上的加利福尼亚放射性离子束升级装置（CARIBU）通过原子在~1 Ci， 252Cf裂变源中的自发裂变产生的。对系统的改进使我们能够在接近裂变产生的10-5%的核素中进行10-7的精度（delta-m/m）测量。一种新的相位成像测量技术的实施使我们能够在减少观测时间的同时获得分辨率的显着增加，这是对半衰期短的核素测量的显着改进。我们的测量集中在那些在天体物理计算中被确定为对稀土峰中计算的丰度影响最大的原子核上。一个名为N = 126工厂的新设施正在开发中，它将使CPT能够接触到被认为对r过程的最后一个丰度峰值有贡献的类似原子核。******在第二个离子阱系统中，离子可以被困在一个充满气体的、低温的、开放几何的、射频四极离子阱（RFQ）中，这为研究β粒子和在被困离子衰变过程中发射的中微子之间的相关性提供了一个独特的机会。用该装置对A=8体系进行了弱相互作用粒子物理理论的实验研究。这个陷阱也可以用来观察裂变碎片在衰变过程中β延迟中子的发射。一个专门用于延迟中子工作的陷阱系统正在建造中。******所要求的数额将用于支付CPT质谱仪（完全由加拿大拥有）的操作和维护费用。加拿大团队的费用包括两名研究生的津贴，一名博士后的工资和往返该设施的旅费。