Upgrade of Noble Gas Mass Spectrometer (VG5440) for Use in the Earth and Environmental Sciences

该合同将允许对已经运行了18年的惰性气体质谱仪(VG5440)的电子设备进行升级。此次升级将恢复并显着增强机器的测量能力，以便我们可以在霓虹灯和氮同位素地球化学领域启动新的研究。我们计划或正在进行当代Ne和N_2研究的4个领域的研究：(1)利用宇宙起源的~(21)Ne进行表面暴露测年。我们计划改进鉴定天然材料中宇宙射线产生的~(21)Ne的方法，特别是解决基于~(21)Ne、~(10)Be和~(26)Al核素的年龄差异。(2)大洋岛玄武岩(OIB)的Ne同位素系统学。我们计划在不同类型的OIB中寻找Ne同位素的不均一性。为了进一步评估He和Ne之间的关系，我们以冰岛(和其他OIB)样品为目标，这些样品的3He/4He值在全球名列前茅。(3)利用Ne同位素进行地下水补给研究。通过研究某些含水层系统中发现的“过剩空气”成分，霓虹灯有可能确定地下水的补给机制。(4)确定了“富集型”地幔的氮同位素体系。我们将冰岛和邻近的雷克扬斯山脊作为主要地点，以深入了解地球地幔的N同位素特征变化。此外，这项提议将更新一个专门的霓虹灯同位素设施，其主要作用是培训研究生和博士后访客。迄今为止，已有相当数量的研究人员利用斯克里普斯/加州大学可持续发展分校的实验室接受了惰性气体地球化学方面的培训，这笔资金将使这一传统得以延续。

This award will permit the upgrade of the electronics units of a noble gas mass spectrometer (VG5440) which has now been in operation for over 18 years. The upgrade will restore and significantly enhance the measurement capabilities of the machine so that we can initiate new studies in the field of neon and nitrogen isotope geochemistry. We plan to or are pursuing studies in 4 areas of contemporary Ne and N2 research: (1) Surface exposure dating using cosmogenic 21Ne. We plan improvements in the methodology of identifying cosmic-ray-produced 21Ne in natural materials, specifically to resolve discrepancies between ages based on 21Ne, 10Be and 26Al nuclides. (2) Neon isotope systematics of ocean island basalts (OIB). We plan to search for Ne isotopic heterogeneity in various classes of OIB. We seek to further evaluate the relationship between He and Ne by targeting Icelandic (and other OIB) samples which have amongst the highest 3He/4He values worldwide. (3) Groundwater recharge studies utilizing Ne isotopes. Neon has the potential to identify mechanisms of groundwater recharge through studies of the 'excess air' component identified in some aquifer systems. (4) Defining the nitrogen isotope systematics of the 'enriched' mantle. We have targeted Iceland and the adjacent Reykjanes Ridge as prime localities to gain insight into the characteristic N-isotope variations of the terrestrial mantle. Furthermore, this proposal will update a dedicated neon isotope facility whose primary role is training of graduate students and post-doctoral visitors. To date, a significant number of established researchers have received their training in noble gas geochemistry using the Scripps/UCSD laboratories and this funding will allow this tradition to continue.