High-precision spectroscopy and exotic nuclear structure

这项拨款申请支持我的小组-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-他们的研究沿着三个主要主题进行调整;在TRIUMF-ISAC设施中开发用于中子探测的下降探测器， 加速束核反应和β-缓发中子 测量，核结构研究，以了解原子核中集体的起源和性质，以及对基本对称性测试和寻找标准模型之外的物理学非常重要的原子核结构研究。 Descant是一个耗资200万美元的CFI项目，是一个由70个氘代苯液体闪烁体探测器组成的阵列，可以与GRIFFIN伽马射线光谱仪结合使用，以利用TRIUMF提供的新功能，ARIEL设施的开发将提供强中子丰核束，其中许多将具有大量的β延迟中子发射分支。当与TIGRESS伽马射线谱仪耦合时，它为加速富中子束引起的反应提供了灵敏的通道选择器。 我们的核结构研究探讨了集体的发展，主要是在Cd区。 将核寿命测量结果与非常高的统计β衰变测量结果相结合，可以详细绘制集体图。Cd同位素被认为是球形振动运动的最佳例子，但我们最近的工作对此提出了质疑。我们正在将我们的研究扩展到Z=50以上的区域，即Te和Xe同位素，并进行高统计的β衰变实验。我们的研究包括在德国加兴的迈尔-莱布尼茨实验室用Q3 D磁谱仪进行的核子转移和非弹性散射反应的研究。 除了上述研究，我的团队还积极进行核结构研究，以支持基本对称性测试。 使用Q3 D摄谱仪，进行实验以测试在超允许费米β衰变中重要的同位旋对称性破缺校正项的结构计算的准确性-用于导出CKM矩阵的Vud元素。 一个重大的新举措进行的是在199 Hg附近的原子核的调查，目的是约束模型的199 Hg希夫矩。 原子电偶极矩存在的最严格极限是199 Hg。然而，由于缺乏光谱数据，特别是E1、E2和E3强度分布的数据，199 Hg的希夫矩模型受到了阻碍。在我们的计划的第一阶段，我们正在研究198,200 Hg通过非弹性散射（d，d '）反应和单中子转移到199 Hg。这些研究将通过（n，n 'gamma）和（p，p' gamma）反应扩展到γ射线测量。

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.