Laser spectroscopy on exotic nuclei

奇异核的激光光谱

• 批准号: SAPPJ-2014-00023
• 负责人: Pearson, Matthew
• 金额: $ 8.38万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Project
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=589191
• 关键词: Laser; spectroscopy; exotic; nuclei

Fast beam, collinear laser spectroscopy has long been seen as a highly sensitive method with which to probe nuclear structure. When coupled with high intensity radioactive beam facilities where long chains of isotopes of many chemical elements are available this provides invaluable information on both the nuclear ground state as well as any long lived isomeric states. The use of high resolution laser spectroscopy on atomic electrons which in turn directly probe the nucleus leads to a non-destructive, highly sensitive probe that can extract effects in a largely model independent way. In general it is possible to extract the nuclear spin, magnetic dipole and electric quadrupole moments as well as the RMS charge radii. In some cases it is also possible to extract higher order affects such as the nuclear magnetisation radius. As such the results from this work have a far reaching impact across many areas of nuclear physics ranging from basic nuclear structure through weak interactions studies to fundamental symmetry tests of the standard model. This proposal aims to continue the work that has been ongoing for the past five years at the ISAC facility at TRIUMF as part of a collaboration between TRIUMF and the Universities of McGill and Manchester (UK). All measurements are performed at the ISAC facility at TRIUMF and utilise the unique capabilities of the facility. The use of Titan's radio frequency quadrupole buncher to bunch the continuous ISAC beam gives an increase in signal to background of over 3 orders of magnitude compared to conventional CW spectroscopy. Further refinments and improvements to the laser and data aquisition systems have allowed physics to be extracted from beams with intensities as low as a few thausand ions per second in only a few hours. The following initiatives are either planned or ongoing. Working with the Francium group at TRIUMF a study of the neutron deficient Francium isotopes has been started. To date this has yielded information on the nuclear magnetisation distributions from the neutron magic number N=126 out to the subshell closure at N=118. The group has also investigated the nuclear structure from Francium-208 out to Fr-204 confirming and identifying 2 isomers in each of Fr-206 and Fr-204 whilst showing an onset of deformation and change away from the expected single particle nature in this region of the nuclear chart. This study will be increased further with the idea of investigating the newly discovered isomeric states in the odd-A nuclei in this region. Working with the 8pi decay spectroscopy group as well as the Titan mass trapping group the structures of the neutron rich Rb isotopes have been investigated. This has led to the first direct confirmation of an isomeric state in Rb-98 - it is proposed to continue this study beyond Rb-100 where the nuclear structure is of astronomical interest. The collaboration between several experimental groups at ISAC allows for a fuller picture of areas of the nuclear chart to be investigated, a unique feature of the facility. This is most evident in the CKM matrix studies. This group has recently measured the charge radius of Rb-74 which was immediately used to refine the CKM matrix element calculations along with other measurements from ISAC. This collaboration intends to extend these measurements to include the next heaviest case of Ga-62. In addition to this technical development into both optical and ion manipulation techniques will allow the start of studies into the rare earth region with an initial view to investigating predictions of triaxial ground states within light La nuclei. The versitility of the technique allows for a varied and versitile programme with the flexibility to respond to requests and situations as they arise.

快速束，共线激光光谱长期以来一直被视为探测核结构的高度敏感方法。当有许多化学元素的同位素链的长链中，可提供许多化学元素的链条时，这提供了有关核基地状态以及任何长期寿命的同属状态的宝贵信息。在原子电子上使用高分辨率激光光谱法又直接探测细胞核会导致无损，高度敏感的探针，可以以很大的独立方式提取效果。通常，可以提取核自旋，磁偶极子和四极杆矩以及RMS电荷半径。在某些情况下，也可能提取高阶影响，例如核磁性半径。因此，这项工作的结果在许多核物理学领域都产生了很大的影响，从基本的核结构到弱相互作用研究到标准模型的基本对称测试。 该提议旨在继续在凯旋与麦吉尔大学和曼彻斯特大学（英国）合作的一部分，过去五年来一直在Triumf的ISAC工厂进行的工作。 所有测量均在Triumf的ISAC设施进行，并利用该设施的独特功能。与传统的CW光谱相比，使用Titan的射频四极束束束束束束束束的iSAC光束可将信号增加到超过3个数量级的背景。对激光和数据育种系统的进一步改进和改进使物理可以从低至几个小时的强度低至几个thausand离子的光束中提取。 以下计划是计划的或正在进行的。 与Triumf的Francium组合作，已经开始对中子缺乏的同位素的研究。迄今为止，这已经产生了有关中子魔术数n = 126到n = 118的子壳闭合的核磁化分布的信息。该小组还研究了从Francium-208到FR-204的核结构，确认并确定了FR-206和FR-204的每个异构体，同时显示了变形的发作，并从核图表的这一区域中的预期单个粒子开始变化。随着研究该区域奇数-A核中新发现的异构体状态的想法，这项研究将进一步增加。 已经研究了与8PI衰变光谱群以及泰坦质量捕获组一起工作的，已经研究了富含中子的RB同位素的结构。这导致了RB-98中异构体状态的首次直接确认 - 提议继续这项研究以外的RB-100，其中核结构具有天文学兴趣。 ISAC的几个实验组之间的合作允许研究核图表的区域，这是该设施的独特特征。 这在CKM矩阵研究中最明显。该组最近测量了RB-74的电荷半径，该半径立即用于完善CKM矩阵元件计算以及ISAC的其他测量结果。这种合作旨在扩展这些测量值，以包括GA-62的下一个最重的情况。 除了对光学和离子操纵技术的技术发展外，还将开始研究稀土区域，并初步观点研究光LA核内三轴基态的预测。 该技术的多功能性允许一个多样化的多样性程序，可以灵活地响应其出现的请求和情况。