A Compact System for Continuous-flow Accelerator Mass Spectrometry

0321045 Hayes马萨诸塞州伍兹霍尔海洋研究所（WHOI）获得的这项主要研究仪器奖为开发一种紧凑、连续流动的加速器质谱仪提供了资金，该质谱仪专门用于监测连续流动气流中14C（放射性碳）相对于其他碳同位素的水平。该仪器对放射性碳浓度（信号/噪声= 3）的反应显著（信号/噪声= 3），其浓度比现代大气中的放射性碳浓度低10倍，样品中碳含量小至1微克。它将能够连续分析色谱出水，并确定单个色谱峰中14C的丰度。以前的工作已经证明，对天然样品中单个有机化合物的放射性碳分布的调查可以揭示这些化合物的来源，而这种新仪器将有可能将这些结果扩展到不同样品中的各种化合物，解决有关自然环境中碳循环的重要问题。具体的初步计划应用包括研究二氧化碳向大气的释放和重建古代气候。油气循环研究将利用化石烃中缺乏放射性碳的特点，为石油等自然环境中的污染物提供强有力的负示踪剂。该仪器将由两个大磁铁、一个粒子加速器、一个静电偏转系统和一个粒子计数探测器以及一个微波离子源构成，微波离子源是一个关键子系统，利用微波能量产生等离子体，从中提取正碳离子。微波离子源的原型已经在WHOI的国家海洋科学加速器质谱（NOSAMS）设施中建立并进行了测试。新仪器将被安置在一个正在建造的新实验室中，以便扩大NOSAMS，并作为该设施的一部分进行管理。一旦建成，它将作为一个由联邦政府资助的合格研究人员和其他人共享使用的设施，类似于NOSAMS现有的加速器质谱仪。该仪器奖由美国国家科学基金会海洋科学部资助。伍兹霍尔海洋研究所从非联邦基金中提供费用分摊支持

0321045 Hayes This Major Research Instrumentation award to Woods Hole Oceanographic Institution (WHOI) in Massachusetts provides funds for development of a compact, continuous-flow, accelerator mass spectrometer, designed specifically for monitoring levels of 14C (radiocarbon) relative to other carbon isotopes in a continuously flowing gas stream. The instrument will respond significantly (signal/noise = 3) to concentrations of radiocarbon ten-fold lower than those in the modern atmosphere in samples as small as one microgram carbon. It will be capable of continuously analyzing chromatographic effluents and of determining the abundance of 14C in individual chromatographic peaks. Previous work has demonstrated that surveys of radiocarbon distribution within individual organic compounds from natural samples can reveal the sources of those compounds, and this new instrument will make it possible to extend those results to a wide variety of compounds in diverse samples, addressing important questions about carbon cycling in natural environments. Specific initial planned applications include study of releases of carbon dioxide to the atmosphere and the reconstruction of ancient climates. Research on hydrocarbon cycling will take advantage of the lack of radiocarbon in fossil hydrocarbons, thus providing a strong negative tracer for petroleum and other pollutants in natural environments. The instrument will be constructed from two large magnets, a particle accelerator, an electrostatic deflecting system and a particle-counting detector in addition to a microwave ion source, a key subsystem that uses microwave energy to create a plasma from which positive carbon ions can be extracted. A prototype of the microwave ion source has been built and tested previously at the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility at WHOI. The new instrument will be housed in a new laboratory being constructed to allow expansion of NOSAMS, and managed as part of that facility. Once built, it will be operated as a shared-use facility for qualified, federally-funded researchers and others, similar to the existing accelerator mass spectrometer at NOSAMS. This instrumentation award is supported by the Division of Ocean Sciences at NSF. Woods Hole Oceanographic Institution provides cost sharing support from non-federal funds.***