Acquisition of a Helix SFT Noble Gas Mass Spectrometer

购买 Helix SFT 稀有气体质谱仪

• 批准号: 1826965
• 负责人: Kenneth Farley
• 金额: $ 34.34万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2019-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1826965&HistoricalAwards=false
• 关键词: Acquisition; Helix; SFT; Noble; Gas

This grant supports continued innovation and application of techniques of He isotope geochemistry to address Earth science problems. The grant will be used to purchase a new He isotope mass spectrometer capable of making precise and accurate He isotope abundance measurements even on very small quantities of helium. The instrument replaces a decades-old predecessor and requires no modification to the existing hardware for extracting gases from rocks and minerals for analysis. This instrument will be used in support of many Earth science subdisciplines and will be the main tool used by multiple undergraduate and graduate students and postdoctoral investigators in their studies.The two isotopes of He, 3He and 4He, provide a wealth of information on the origin and history of terrestrial rocks. 4He in rocks is almost exclusively derived from α-decay of the elements U and Th. Accumulation of 4He in minerals allows a unique form of chronometry. Because He diffuses out of minerals at elevated temperatures characteristic of burial to a few km depth in the crust, the accumulated 4He in minerals can be used to determine when rocks were brought to the Earth's surface by erosion or faulting. Such data provide important insights to key geologic processes such as the timing and causes of mountain building. 3He in rocks and minerals can come from more unusual sources. For example, 3He is produced when cosmic rays interact with the elements that make up minerals in the uppermost ~ 2 meters of the crust. This too acts as a chronometer, but a chronometer that can be used to measure erosion rates and also to establish when rocks first became exposed at the surface. The latter technique is one of the central tools in establishing the glaciation history and Milankovitch-driven climate change over the last few tens of thousands of years. In marine sediments, 3He is derived from the accumulation of cosmic dust. By measuring 3He concentrations in sequences of marine sediments it is possible to establish sedimentation rates (another key indicator of time) and, in some cases, to identify major cosmic-dust producing events such as the rare destructive collision of many-km-sized asteroids.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该赠款支持氦同位素地球化学技术的持续创新和应用，以解决地球科学问题。 这笔赠款将用于购买一台新的 He 同位素质谱仪，即使对极少量的氦，也能进行精确的 He 同位素丰度测量。该仪器取代了已有数十年历史的前身，无需修改现有硬件即可从岩石和矿物中提取气体进行分析。该仪器将用于支持许多地球科学分支学科，并将成为多个本科生、研究生和博士后研究人员在研究中使用的主要工具。He 的两种同位素 3He 和 4He 提供了有关起源的丰富信息和陆地岩石的历史。 4He在岩石中几乎完全来源于元素U和Th的衰变。 4He 在矿物中的积累形成了一种独特的计时方式。由于 He 在埋藏至地壳几公里深度的高温下从矿物中扩散出来，因此矿物中积累的 4He 可用于确定岩石何时通过侵蚀或断层带到地球表面。这些数据为关键地质过程（例如造山的时间和原因）提供了重要的见解。 3岩石和矿物中的氦可能来自更不寻常的来源。例如，当宇宙射线与地壳最上面约 2 米的矿物元素相互作用时，就会产生 3He。这也可以用作计时器，但计时器可以用来测量侵蚀率，也可以用来确定岩石第一次暴露在地表的时间。后一种技术是建立过去几万年冰川历史和米兰科维奇驱动的气候变化的核心工具之一。在海洋沉积物中， 3He 来自宇宙尘埃的积累。通过测量海洋沉积物序列中的 3He 浓度，可以确定沉积速率（时间的另一个关键指标），并且在某些情况下，可以识别主要的宇宙尘埃产生事件，例如数公里大小的小行星罕见的破坏性碰撞该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。