SGER: Redetermining the Half-Life of 187 Re

SGER：重新确定 187 Re 的半衰期

• 批准号: 0228307
• 负责人: Bernhard Peucker-Ehrenbrink
• 金额: $ 2.27万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-15 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0228307&HistoricalAwards=false
• 关键词: SGER; Redetermining; Half; Life; 187

Peucker-EhrenbrinkEAR-0228307In contrast to many widely used geochronometers, the uncertainty in the experimentally determined half-life of 187 Re (4.23 plus or minus 0.13 x 10E10 yr; Lindner et al., 1986, 1989) is large (~3%). This uncertainty currently limits the application of the Re-Os system as a precise chronometer. This proposal requests support for an experimental determination of the 187 Re half-life using 1 kg of Re originally used by Lindner et al. (1986, 1989) in their experimental determination of the 187 Re half-life. The aliquots will be sealed in glass stills equipped with break seals to prevent loss of volatile Os during storage. Storage periods of 0.5-2.5 years are sufficient to generate 187 Os/ 188 Os 1 in all except the first experiment, ensuring that the precision on the 187 Os/ 188 Os is not limited by the abundance of radiogenic 187 Os. Five independent determinations of the 187 Re half-life will be made using plasma ionization multicollector mass spectrometry on initially Os-free perrhenic acid. The expected overall uncertainty of the 187 Re half-life using this approach is 0.4%.

Peucker-EhrenbrinkEAR-0228307与许多广泛使用的地质计时仪相比，实验测定的187Re(正负0.13×10E10年；Lindner等，1986，)的半衰期的不确定度很大(~3%)。这种不确定性目前限制了Re-Os系统作为精密天文计时器的应用。该提案要求支持使用Lindner等人最初使用的1公斤Re对187 Re半衰期的实验确定。(1986,1989)对187Re的半衰期进行了实验测定。等分将被密封在装有破裂密封件的玻璃蒸馏器中，以防止在储存过程中挥发性O的损失。除第一次实验外，0.5-2.5年的存储周期足以产生187 Os/188 Os 1，确保187 Os/188 Os的精度不受放射性成因187 Os丰度的限制。用等离子体电离多收集器质谱对初始不含Os的高黎酸进行了5次187Re半衰期的独立测定。用该方法对187个Re的半衰期进行预测，总的不确定度为0.4%。