用HPGeγ谱方法测定了一个采集自东太平洋的沉积物岩心的^(230)Th和^(231)Pa。对其深度分布规律及其所揭示的海洋学意义进行了研究,用^(230)Th_(ex)、^(231)Pa_(ex)和^(231)Pa_(ex)/^(230)Th_(ex)法计算得到完全一致的沉积速率,平均值为...用HPGeγ谱方法测定了一个采集自东太平洋的沉积物岩心的^(230)Th和^(231)Pa。对其深度分布规律及其所揭示的海洋学意义进行了研究,用^(230)Th_(ex)、^(231)Pa_(ex)和^(231)Pa_(ex)/^(230)Th_(ex)法计算得到完全一致的沉积速率,平均值为1.6 mm/ka。用^(231)Pa_(ex)/^(230)Th_(ex)比值法研究了100 ka时间尺度海洋输出生产力的变化,给出60～80 ka BP期间研究海域有高的输出生产力。展开更多
230Pa was produced through the 232Th(p,3n)230Pa reaction in the irradiated ThO2 powder targets with 35 MeV proton beam. Pa was radiochemically separated from ThO2 and other reaction products, and then thin sources of ...230Pa was produced through the 232Th(p,3n)230Pa reaction in the irradiated ThO2 powder targets with 35 MeV proton beam. Pa was radiochemically separated from ThO2 and other reaction products, and then thin sources of 230Paβ-230U were prepared. The polyethylene-terephthalate (lavsan) films were selected as solid track detector searching for the cluster activity of 230U. The gamma activity of 230Pa in the sources was measured using a HPGe detector. The lavsan films were etched in NaOH solution and the etched films were scanned under an optical microscope. The exotic nuclear decay of 230U by emission of 22Ne was observed. A branching ratio relative to α decay was deduced, B =λNe/λα= (1.3±0.8)×10-14 for 22Ne emission from 230U.展开更多
A new method suitable for determining specific activity of 230Th in uranium ore samples is built. The method is characterized by adding the 230Th/ 232Th standard dilution agent with lower activity ratio (Its 230Th/ 23...A new method suitable for determining specific activity of 230Th in uranium ore samples is built. The method is characterized by adding the 230Th/ 232Th standard dilution agent with lower activity ratio (Its 230Th/ 232Th activity ratio and Th have been known) to the samples and using isotopic dilution analysis. The method can be applied to analyses of 230Th specific activity in various 230Th/ 232Th activity ratio samples. The precision can also be improved.展开更多
We have pointed out that, after excluding operational errors, the 230Th/234U age of stalagmitic calcite shows a satisfactory internal consistency. However, good precision of the results, together with its coherence wi...We have pointed out that, after excluding operational errors, the 230Th/234U age of stalagmitic calcite shows a satisfactory internal consistency. However, good precision of the results, together with its coherence with stratigraphic sequence, is only a necessary but not a sufficient condition for ascertaining its validity.展开更多
文摘用HPGeγ谱方法测定了一个采集自东太平洋的沉积物岩心的^(230)Th和^(231)Pa。对其深度分布规律及其所揭示的海洋学意义进行了研究,用^(230)Th_(ex)、^(231)Pa_(ex)和^(231)Pa_(ex)/^(230)Th_(ex)法计算得到完全一致的沉积速率,平均值为1.6 mm/ka。用^(231)Pa_(ex)/^(230)Th_(ex)比值法研究了100 ka时间尺度海洋输出生产力的变化,给出60～80 ka BP期间研究海域有高的输出生产力。
基金Supported by the National Natural Science Foundation of China (No. 10075063) Chinese Academy of Sciences (TK95T-03)
文摘230Pa was produced through the 232Th(p,3n)230Pa reaction in the irradiated ThO2 powder targets with 35 MeV proton beam. Pa was radiochemically separated from ThO2 and other reaction products, and then thin sources of 230Paβ-230U were prepared. The polyethylene-terephthalate (lavsan) films were selected as solid track detector searching for the cluster activity of 230U. The gamma activity of 230Pa in the sources was measured using a HPGe detector. The lavsan films were etched in NaOH solution and the etched films were scanned under an optical microscope. The exotic nuclear decay of 230U by emission of 22Ne was observed. A branching ratio relative to α decay was deduced, B =λNe/λα= (1.3±0.8)×10-14 for 22Ne emission from 230U.
文摘A new method suitable for determining specific activity of 230Th in uranium ore samples is built. The method is characterized by adding the 230Th/ 232Th standard dilution agent with lower activity ratio (Its 230Th/ 232Th activity ratio and Th have been known) to the samples and using isotopic dilution analysis. The method can be applied to analyses of 230Th specific activity in various 230Th/ 232Th activity ratio samples. The precision can also be improved.
文摘We have pointed out that, after excluding operational errors, the 230Th/234U age of stalagmitic calcite shows a satisfactory internal consistency. However, good precision of the results, together with its coherence with stratigraphic sequence, is only a necessary but not a sufficient condition for ascertaining its validity.
