Upgrade of a Helium Isotope Mass Spectrometer

0549533 Kurz这笔赠款用于支持伍兹霍尔海洋研究所（WHOI）现有的氦同位素质谱仪的升级，该质谱仪专用于测量岩石和矿物。目前的质谱仪是全自动的，自20世纪80年代初以来一直在连续运行，但有许多过时的组件。 升级的组成部分将包括：（1）用一台运行视窗XP的现代化奔腾个人电脑取代PDP-11计算机控制系统;（2）升级低温系统，更换氦压缩机和两个冷头中的一个;（3）升级真空系统，新的分子泵和特高压阀;（4）安装新的离子光学器件、一个电子管探测器和开发一个新的离子源;以及5）获得新的四极质谱仪，以在进入惰性气体质谱仪的磁扇区之前预先测量样品气体。 所要求的升级预计将使系统的检测极限降低约10倍（至约1000个原子3 He）。这将通过安装离子计数检测电子设备和能量过滤器（在电子倍增器上）、升级离子源和升级超高真空部件来实现。升级后的质谱仪将有助于根据对地幔矿物中3 He/4 He比率的高精度、低检测限分析，包括对从夏威夷科学钻探项目回收的材料进行分析，对地幔动力学/脱气进行研究，因为该项目只有少量样品可供研究。宇宙成因3 He测量也将用于确定地球表面物质的暴露年龄，以支持古气候研究（例如冰碛物的年代测定）和景观演变研究。 升级后的He专用惰性气体质谱仪是WHOI成本中心（WHOI同位素地球化学设施）的一部分，将提供给WHOI科学家和麻省理工学院-WHOI联合博士学位的学生。该计划，以及更广泛的美国科学界。 将开发一个新的网站，宣传互联网治理论坛现有的分析能力。

0549533KurzThis grant supports upgrade of an existing helium isotope mass spectrometer dedicated to measurements of rocks and minerals at Woods Hole Oceanographic Institution (WHOI). The current mass spectrometer is fully automated and has been operating continuously since the early 1980s but has many antiquated components. Components of the upgrade would include: 1) replacement of a PDP-11 computer control system with a modern Pentium PC running Windows XP; 2) upgrade of the cryogenic system replacement of helium compressor and one of two cold heads; 3) upgrade of the vacuum system new turbomolecular pumps and UHV valves; 4) installation of new ion optics, a Channeltron detector and development of a new ion source; and 5) acquisition of a new quadrupole mass spectrometer to premeasure sample gases prior to inlet into the magnetic sector of the noble gas mass spectrometer. The requested upgrade is expected to lower the detection limit of the system by roughly a factor 10 (to ~ 1000 atoms 3He). This would be accomplished by installing ion counting detection electronics and an energy filter (on the electron multiplier), by upgrading the ion source, and by upgrading the ultra high vacuum components. The upgraded mass spectrometer would facilitate studies of mantle dynamics/degassing based on high precision, low detection limit analyses of 3He/4He ratios in mantle minerals, including analysis of materials recovered from the Hawaiian Scientific Drilling Project, where only small samples are available for study. Cosmogenic 3He measurements will also be used to determine the exposure age of materials at the earth's surface to support paleoclimate studies (e.g, dating of glacial moraines) and research on landscape evolution. The upgraded He dedicated noble gas mass spectrometer is part of a WHOI cost center (the WHOI Isotope Geochemistry Facility) and will be available to WHOI scientists and students in ther MIT-WHOI joint Ph.D. program, and also to the broader U.S. science community. A new web site will be developed to advertise the analytical capabilities available in the IGF.