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

EAR-0326205南加州大学欧文分校、伍兹霍尔海洋研究所和亚利桑那大学的实验室使用加速器质谱仪(AMS)测量宇宙成因的同位素，主要是14C，支持母机构和许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。用于将感兴趣的样品转换为强负离子束的可靠和稳定的离子源对AMS光谱仪的整体性能绝对至关重要。在这项提议中合作的三个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)制造。我们将与NEC合作一项为期两年的计划，对离子源进行改进，以提高产量、更好的可靠性和可维护性。信号源输出低、可靠性差以及维护信号源所需的时间是目前全球AMS实验室用户延迟和测量质量差的最大原因。加州大学欧文分校的工作将集中在Cs进料以及Cs和负离子几何结构的变化上，目的是增加产量和改善可靠性。伍兹霍尔将研究有源抽气和其他真空改进，以增加产量，并将重新设计离子源引出区域，以提高可靠性。亚利桑那州将改进Cs电离器组件和聚焦电极的内部安装安排，并对样品对准程序进行更改，从而减少维修停机时间。然后将对每个实验室最初开发的全套修改进行评估，并将在三个机构的来源和NEC产生的新来源中纳入最佳组合。结果将被传递给AMS社区，让使用AMS的许多学科从由于更好的源性能而提高的测量质量中获得科学上的好处。

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.