Collaborative Research: AMS Ion Source Development at University of California, Irvine, Woods Hole Oceanographic Institution, University of Arizona and National Electrostatics Corp

位于欧文的加州大学、伍兹霍尔海洋研究所和亚利桑那大学的Southon实验室使用加速器质谱法（AMS）测量宇宙成因同位素，主要是14 C，支持母机构和众多外部研究人员的研究。对这些分析的需求来自许多科学领域，包括：地质学、考古学、物理学、地理学、海洋学、大气科学、水文学、生物学、艺术史、法医学和工程学。 一个可靠稳定的离子源将感兴趣的样品转化为强负离子束，对AMS谱仪的整体性能至关重要。参与这项提议的三个AMS实验室目前使用四种版本的MC-SNICS Cs溅射离子源，由威斯康星州米德尔顿的国家静电公司（NEC）建造。 我们将与NEC合作开展一项为期2年的项目，对离子源进行改进，以提高输出功率、提高可靠性和改善可维修性。源输出低、可靠性差和源维护所需的时间是目前造成全球AMS实验室用户延迟和测量质量差的最大原因。 在加州大学欧文分校的工作将集中在改变铯饲料和铯和负离子的几何形状，旨在增加输出和提高可靠性。 伍兹霍尔将研究源的主动抽气和其他真空改进以增加输出，并将重新设计离子源提取区域以提高可靠性。 亚利桑那州将实施改进的内部安装安排的铯电离器组件和聚焦电极，加上改变样品对准程序，导致减少维修停机时间。 然后将对每个实验室最初开发的一整套修改进行评估，并将在三个机构的源和NEC生产的新源中纳入最佳设置。结果将传递给整个AMS社区，使许多使用AMS的学科能够从更好的源性能带来的测量质量改进中获得科学效益。

EAR-0326205SouthonLaboratories at University of California at Irvine, Woods Hole Oceanographic Institution, and University of Arizona use accelerator mass spectrometry (AMS) to measure cosmogenic isotopes, primarily 14C, supporting research at the parent institutions plus numerous external researchers. The demand for these analyses comes from many scientific fields, including: geology, archaeology, physics, geography, oceanography, atmospheric sciences, hydrology, biology, art history, forensic sciences and engineering. A reliable and stable ion source for converting samples of interest into intense beams of negative ions is absolutely critical to the overall performance of an AMS spectrometer. The three AMS laboratories collaborating in this proposal currently use four versions of the MC-SNICS Cs sputter ion source, built by National Electrostatics Corp (NEC) of Middleton, WI. We will collaborate with NEC in a 2-year program to modify the ion source for increased output, better reliability, and improved serviceability. Low source output, poor reliability, and time required for source maintenance are currently the largest causes of delay and poor measurement quality for users of AMS laboratories worldwide. Work at UC Irvine will concentrate on changes to the Cs feed and to the Cs and negative ion geometries aimed at increasing output and improving reliability. Woods Hole will investigate active pumping of the source and other vacuum improvements for increased output, and will redesign the ion source extraction region for improved reliability. Arizona will implement improved internal mounting arrangements for the Cs ionizer assembly and focusing electrodes, plus changes to sample alignment procedures leading to reduced servicing down time. A full suite of the modifications initially developed at each laboratory will then be evaluated, and an optimal set will be incorporated in the sources at the three institutions and in new sources produced by NEC. The results will be passed on to the AMS community at large, to allow the many disciplines using AMS to reap the scientific benefits resulting from improved measurement quality due to better source performance.