Characterization of highly charged ion beams and post acceleration of neutron rich Sn isotopes using an electron beam ion sorce

使用电子束离子源表征高电荷离子束和富中子 Sn 同位素的后加速

• 批准号: SAPPJ-2021-00022
• 负责人: Ames, Friedhelm
• 金额: $ 1.46万
• 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: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=743118
• 关键词: Characterization; highly; charged; ion; beams

The goal of the CANREB facility at TRIUMF is to produce re-accelerated high purity beams of heavy short-lived rare isotopes. This will enable a wide variety of direct reaction studies like nucleon transfer reactions and Coulomb excitation to be performed. The aims include probing the evolution of nuclear shell structure and the unitarity of the CKM matrix, understanding shape coexistence in nuclei, and constrain neutron capture rates relevant for heavy element nucleosynthesis. A suite of state-of-the-art experimental facilities is in place at ISAC for performing these studies. Key requirement for these experiments is the availability of re-accelerated beams with high intensity and purity. This proposal will concentrate on the acceleration of neutron rich Sn isotopes. Experimental proposals for transfer reaction measurements with neutron-rich Sn beams have been evaluated by the TRIUMF experiments evaluation committee (EEC) with high priority but are still waiting for the development which is proposed here. Efficient acceleration of heavy ions in linear accelerators requires highly charged ions. Rare isotopes at an ISOL facility like ISAC and ARIEL at TRIUMF are produced by bombarding solid targets with high energy particle beams. The rare isotopes are extracted as a beam of mainly singly charged ions making charge state breeding essential for the acceleration. Furthermore, the isotope production and the ionization process are not very selective. Isobaric contamination of highly abundant isobars cannot be avoided. In the case of neutron rich Sn isotopes, the background consists mainly of Cs and Ba isotopes. Over the last few years, a new system for the charge state breeding and purification, CANREB (CANadian Rare isotope facility with Electron Beam Ion source) has been set up at TRIUMF. First tests and commissioning have started. An Electron beam ion source (EBIS) is used for the charge state breeding. 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. Highly charged ions are extracted as bunches at a pulse repetition rate of up to 100 Hz. CANREB and the ISAC accelerator will allow accelerator and nuclear physics students to investigate the most advanced radioactive ion post-accelerator system to date. The objective of this proposal is to develop tools and methods to characterize and optimize beam properties to match requirements at the experimental stations. Advanced beam optics simulations codes will be used to model the beam transport throughout the entire chain and outputs will be compared to measurements. It will include the development of methods to manipulate the pulse structure of the extracted ions and optimizing efficiency and purity by applying techniques like breeding to closed atomic shells in the EBIS. Within this proposal those methods will be applied to neutron-rich Sn isotopes.

TRIUMF的CANREB设施的目标是生产重短寿命稀有同位素的再加速高纯度束流。这将使各种直接反应的研究，如核子转移反应和库仑激发进行。目标包括探测核壳结构的演化和CKM矩阵的么正性，理解核中的形状共存，以及约束与重元素核合成相关的中子俘获率。ISAC拥有一套最先进的实验设施，用于进行这些研究。这些实验的关键要求是具有高强度和高纯度的再加速光束的可用性。该建议将集中于富中子Sn同位素的加速。用富中子Sn束测量转移反应的实验建议已经由TRIUMF实验评估委员会（EEC）以高优先级进行了评估，但仍在等待这里提出的发展。 重离子在直线加速器中的有效加速需要高电荷态的离子。ISOL设施中的稀有同位素，如TRIUMF的ISAC和ARIEL，是通过用高能粒子束轰击固体靶产生的。稀有同位素被提取为主要是单电荷离子的束，使得电荷状态繁殖对于加速至关重要。此外，同位素生产和电离过程的选择性不是很强。高丰度同量异位素的同量异位素污染是不可避免的。在富中子Sn同位素的情况下，背景主要由Cs和Ba同位素组成。在过去的几年里，一个新的系统的电荷态增殖和纯化，CANREB（加拿大稀有同位素设施与电子束离子源）已建立在TRIUMF。第一次测试和调试已经开始。电子束离子源（EBIS）用于电荷状态育种。整个系统包含一个射频四极杆线性Paul阱，用于在注入EBIS之前进行聚束，然后用Nier型质谱仪进行电荷状态选择。高电荷离子以高达100 Hz的脉冲重复率作为束被提取。CANREB和ISAC加速器将使加速器和核物理专业的学生能够研究迄今为止最先进的放射性离子后加速器系统。该提案的目的是开发工具和方法，以表征和优化光束特性，以满足实验站的要求。先进的光束光学模拟代码将用于模拟整个链中的光束传输，并将输出与测量结果进行比较。它将包括开发方法来操纵提取离子的脉冲结构，并通过应用EBIS中的封闭原子壳层繁殖等技术来优化效率和纯度。在这个提议中，这些方法将适用于富中子的Sn同位素。