Acquisition of Intrinsic Ge Gamma Spectrometers

收购本征 Ge 伽马能谱仪

• 批准号: 0650533
• 负责人: Carl Renshaw
• 金额: $ 9.54万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0650533&HistoricalAwards=false
• 关键词: Acquisition; Intrinsic; Ge; Gamma; Spectrometers

This grant provides support for the acquisition of two Germanium gamma ray scintillometers for the analysis of short lived radioisotopes (e.g., 7Be T1/2 = 53 d and 210Pb T1/2 = 22.3 yr). As a result of their short half lives, these fallout radionuclides make excellent tracers of short term riverine bed load residence times. Both 7Be and 210Pb are reactive and readily adsorb to fine grained minerals ( 2 mm) common in fluvial bed loads. Given the differences in their half lives, the activity ratio 7Be/210Pb decreases with increased residence time of the sediments since last exposure to the atmosphere where it acquired its initial fallout activity. The transport of fine sediment (nominal diameter of less than ~2 mm) controls the sequestration of contaminants in fluvial environments. In addition, fine sediment is often a significant component of overall sediment flux, and thus can be an important agent of geomorphic change. The proposed equipment will be immediately employed in NSF-funded research by PIs at Dartmouth College to study the bed residence time of fine sediment in mixed-load rivers with relevance to understanding the effects of dam construction and removal on sediment dynamics and the transport and fate of particle reactive deleterious substances (e.g., trace metals, hydrocarbons). The proposed equipment would impact research and teaching in the Departments of Earth Sciences, Geography, and Environmental Studies at Dartmouth College. The equipment will support undergraduate and graduate student research in riverine sediment dynamics. The PIs plan to involve undergraduate women participating in Dartmouth's Women In Science Program - a program designed to encourage women to enter and continue in science, math, and engineering through mentoring and early hands-on research experience.

这笔拨款资助购置两台锗伽马射线计数器，用于分析短寿命放射性同位素（例如，7 Be的T_（1/2）= 53 d，~（210）Pb的T_（1/2）= 22.3年。 由于其半衰期短，这些沉降物放射性核素成为短期河流推移质停留时间的良好示踪剂。 7 Be和210 Pb都是反应性的，容易吸附在河床负荷中常见的细粒矿物（2 mm）上。 鉴于其半衰期的差异，活性比7 Be/210 Pb的沉积物的停留时间增加，因为最后一次暴露于大气中，它获得了它的初始沉降物的活动。 细颗粒沉积物（标称直径小于2毫米）的迁移控制着河流环境中污染物的固存。 此外，细颗粒沉积物往往是总沉积物通量的重要组成部分，因此可能是地貌变化的一个重要因素。 拟议的设备将立即用于达特茅斯学院PI的NSF资助的研究，以研究混合负荷河流中细泥沙的床停留时间，以了解大坝建设和拆除对泥沙动力学的影响以及颗粒反应性有害物质（例如，痕量金属、碳氢化合物）。 拟议的设备将影响达特茅斯学院地球科学、地理和环境研究系的研究和教学。 该设备将支持本科生和研究生进行河流沉积动力学研究。 PI计划让本科生女性参与达特茅斯的女性科学计划--该计划旨在鼓励女性通过指导和早期实践研究经验进入并继续从事科学、数学和工程学。