Investigation of the charge state breeding for the post acceleration of neutron rich Sn isotopes

位于TRIMUF的CANREB设施的目标是生产重放射性原子核的再加速高纯度束流。这将使各种各样的直接反应研究能够在ISAC II实验大厅的一套最先进的实验站进行。例如，它们包括核子转移反应或库仑激发。这些测量的目的将包括了解核中核壳结构和形状共存的演变，限制与重元素核合成相关的中子俘获率，以及探测超允许贝塔发射体的核结构信息，以测试CKM矩阵的统一性。这些实验变得可行的关键要求是获得高强度和高纯度的稀有同位素束流。*有效的重离子加速需要它们处于高电荷状态。在像ISAC或TRIUMF的Ariel这样的ISOL设施中，放射性离子是通过用高能粒子束轰击固体目标产生的。产物从靶外扩散，直接进入离子源。由于离子源离热靶很近，所以不可能在高电荷态下使用复杂的器件。因此，大多数单电荷离子可以产生，而电荷态的孕育对于加速是必不可少的。此外，同位素的生产和电离过程一般不是很有选择性。在大多数情况下，高度丰富的同量异位素的等压污染是无法避免的。在CANREB项目中，一个高分辨率质量分离器(HRS)将清除来自目标站的离子束中的大多数污染物。电子束离子源(EBIS)将用于电荷态育种。它的优点是离子是在超高真空中产生的，与其他高电荷态离子源相比，这大大减少了残余气体离子的污染。整个系统包括一个射频四极(RFQ)线性Paul陷阱，用于在注入EBIS之前进行聚束，随后是一个Nier型质谱仪，用于选择电荷状态。*拟议的项目将允许加速器和核物理专业的学生和博士后研究迄今为止最先进的稀有同位素后加速器系统。他们将对离子从生产目标通过HRS的传输进行模拟，在EBIS中进行电荷繁殖，并在实验中导致束流特性。此外，还将进行测量并确定最佳运行条件，首先是来自测试离子源的稳定离子，然后是来自ISAC或Ariel的放射性离子。我们的目标是使用富含中子的锡束进行模拟。富中子束转移反应测量意向书已经由TRIUMF SAP-EEC优先进行了评估，但仍在等待这里提出的发展。

The goal of the CANREB facility at TRIMUF is to produce re-accelerated high purity beams of heavy radioactive nuclei. This will enable a wide variety of direct reaction studies to be performed at a suite of state-of-the-art experimental stations at the ISAC II experimental hall. They encompass for example nucleon transfer reactions or Coulomb excitation. The aims of these measurements will include understanding the evolution of nuclear shell structure and shape coexistence in nuclei, to constrain neutron capture rates relevant for heavy element nucleosynthesis, and probing nuclear structure information of super-allowed beta emitters to test the unitarity of the CKM matrix. The key requirement for these experiments to become feasible is the availability of beams of rare isotopes with high intensity and purity.***Efficient acceleration of heavy ions requires them to be in a high charge state. Radioactive ions at an ISOL facility like ISAC or ARIEL at TRIUMF are produced by bombarding solid targets with high energy particle beams. The products diffuse out of the target directly into the ion source. With the ion source in close proximity of the hot target it is impossible to use complicated devices for high charge states. Thus, mostly singly charged ions can be produced and charge state breeding is essential for the acceleration. Furthermore, the isotope production and the ionization processes in general are not very selective. In most cases isobaric contamination of highly abundant isobars cannot be avoided. Within the CANREB project a high resolution mass separator (HRS) will clean up most contaminants in the ion beams from the target stations. An electron beam ion source (EBIS) will be used for the charge state breeding. Its advantage is that ions are created in ultrahigh vacuum, which substantially reduces the contamination from residual gas ions compared to other high charge state ion sources. The entire system contains a radio frequency quadrupole (RFQ) linear Paul trap for bunching before the injection into the EBIS followed by a Nier type mass spectrometer for charge state selection. ***The proposed project will allow accelerator and nuclear physics students and post-docs to investigate the most advanced rare isotope post-accelerator system to date. They will develop simulations of the ion transport from the production target, through the HRS, undergoing charge breeding in the EBIS and leading to beam properties at the experiments. This will be complemented by performing measurements and working out optimized operation conditions, first with stable ions from a test ion source followed by radioactive ions from ISAC or ARIEL. We aim to perform the simulations using neutron-rich Sn beams. Letters of intent for transfer reaction measurements with neutron-rich Sn beams have been evaluated by the TRIUMF SAP-EEC with high priority but are still waiting for the development which is proposed here.