High-precision spectroscopy and exotic nuclear structure

高精度光谱和奇异的核结构

• 批准号: SAPIN-2016-00028
• 负责人: Garrett, Paul
• 金额: $ 12.09万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=693945
• 关键词: precision; spectroscopy; exotic; nuclear; structure

This grant application support my group - currently consisting of 1 Research Associate, 4 PhD, 3 MSc, and 3 undergraduate students - in their research that is aligned along three major themes; development of the DESCANT detector at the TRIUMF-ISAC facility for neutron detection in both*nuclear reactions with accelerated beams, and beta-delayed neutron*measurements, nuclear structure studies to understand the origin and nature of collectivity in nuclei, and nuclear structure studies of nuclei important for fundamental symmetry tests and searches for physics beyond the Standard Model. ***DESCANT, a $2M CFI project, is an array of 70 deuterated benzene liquid scintillator detectors that can be used, in combination with the GRIFFIN gamma-ray spectrometer to take advantage of the new capabilities offered by TRIUMF with the development of the ARIEL facility that will provide intense beams of neutron-rich nuclei, many of which will have substantial beta-delayed neutron emission branches. When coupled to the TIGRESS gamma-ray spectrometer, it offers a sensitive channel selector for reactions induced by accelerated neutron rich beams. ***Our nuclear structure studies have probed the development of collectivity, mainly in the Cd region. Combining results from measurements of nuclear lifetimes with very-high-statistics beta-decay measurements enables a detailed mapping of collectivity. The Cd isotopes were believed to be some of the best examples of spherical vibrational motion, but our recent work has called this into question. We are extending our research into the region above Z=50, namely the Te and Xe isotopes, with high-statistics beta-decay experiments. Our investigations include studies with nucleon transfer and inelastic scattering reactions performed with the Q3D magnetic spectrograph at the Maier-Leibnitz Laboratory in Garching, Germany.***In addition to the above investigations, my group has also been actively pursuing nuclear structure studies to support fundamental symmetry tests. Using the Q3D spectrograph, experiments were performed to test the accuracy of the structure calculations underlying the isospin symmetry breaking correction terms important in superallowed Fermi beta decay - used to derive the Vud element of the CKM matrix. ***A major new initiative undertaken is the investigation of nuclei in the vicinity of 199Hg with the aim of constraining models of the 199Hg Schiff moment. The most stringent limit on the existence of an atomic electric-dipole moment is that for 199Hg. Models of the Schiff moment of 199Hg have been hampered, however, by the lack of spectroscopic data, most notably of the E1, E2, and E3 strength distributions. In the first phase of our program, we are studying 198,200Hg via the inelastic scattering (d,d') reactions and single-neutron transfer into 199Hg. These studies will be extended to gamma-ray measurements via the (n,n'gamma) and (p,p'gamma) reactions. **

该资助申请支持我的团队（目前由 1 名研究助理、4 名博士、3 名硕士和 3 名本科生组成）开展与三个主要主题相一致的研究；在 TRUMF-ISAC 设施中开发 DESCANT 探测器，用于加速束核反应中的中子检测和 β 延迟中子*测量、核结构研究以了解原子核集体的起源和性质，以及核结构研究原子核对于基本对称性测试和寻找标准模型之外的物理非常重要。 ***DESCANT 是一个价值 200 万美元的 CFI 项目，是由 70 个氘化苯液体闪烁体探测器组成的阵列，可与 GRIFFIN 伽马射线光谱仪结合使用，以利用 TRIUMF 开发的新功能ARIEL 设施将提供富中子核的强束流，其中许多将具有大量的 β 延迟中子发射分支。当与 TIGRESS 伽马射线光谱仪耦合时，它为加速富中子束引起的反应提供灵敏的通道选择器。 ***我们的核结构研究探讨了集体的发展，主要是在镉区域。 将核寿命测量结果与极高统计量的β衰变测量结果相结合，可以绘制出详细的总体图。镉同位素被认为是球形振动运动的一些最好的例子，但我们最近的工作对此提出了质疑。我们正在通过高统计β衰变实验将我们的研究扩展到Z=50以上的区域，即Te和Xe同位素。我们的研究包括使用德国加兴 Maier-Leibnitz 实验室的 Q3D 磁谱仪进行的核子转移和非弹性散射反应研究。***除了上述研究之外，我的小组还一直积极开展核结构研究以支持基本对称性测试。 使用 Q3D 摄谱仪进行实验来测试同位旋对称性破缺修正项下的结构计算的准确性，这些修正项在超允许费米 beta 衰变中很重要，用于推导 CKM 矩阵的 Vud 元素。 ***一项重大新举措是研究 199Hg 附近的原子核，目的是约束 199Hg 希夫矩的模型。 原子电偶极矩存在的最严格限制是 199Hg。然而，由于缺乏光谱数据，特别是 E1、E2 和 E3 强度分布，199Hg 希夫矩的模型受到了阻碍。在我们计划的第一阶段，我们正在通过非弹性散射 (d,d') 反应和单中子转移到 199Hg 来研究 198,200Hg。这些研究将通过 (n,n'gamma) 和 (p,p'gamma) 反应扩展到伽马射线测量。 **