Neutron capture cross sections on /sup 138/Ba, /sup 140,142/Ce, /sup 175,176/Lu, and /sup 181/Ta at 30 keV:Prerequisite for investigation of the /sup 176/Lu cosmic clock
Neutron capture cross sections on /sup 138/Ba, /sup 140,142/Ce, /sup 175,176/Lu, and /sup 181/Ta at 30 keV:Prerequisite for investigation of the /sup 176/Lu cosmic clock
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30 keV 下 /sup 138/Ba、/sup 140,142/Ce、/sup 175,176/Lu 和 /sup 181/Ta 上的中子俘获截面：研究 /sup 176/Lu 宇宙钟的先决条件
DOI：
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发表时间：
1980
期刊：
影响因子：
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通讯作者：
F. Kaeppeler
中科院分区：
文献类型：
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作者：
H. Beer;F. Kaeppeler
在30 keV中子能量下，用活化技术测量了/sup 138/Ba，/sup 140，142/Ce，/sup 176/Lu，/sup 181/Ta的俘获截面和/sup 175/Lu对/sup 176/Lu中3.68h同质异能态的俘获截面.在3 MV脉冲货车德格拉夫加速器上，通过/sup 7/Li（p，n）反应产生中子。俘获截面对恒星核合成具有重要意义。用/sup 138/Ba和/sup 140/Ce截面计算了s过程的时间积分平均中子通量为0.22mb/sup-1/。利用这一结果，结合/sup 176/Lu的俘获截面和/sup 175/Lu对/sup 176/Lu中3.68 h同质异能态的俘获截面，对/sup 176/Lu宇宙钟进行了分析.太阳系凝固前太阳物质的平均s过程年龄估计为6 × 10 ~ 9/sup ~ 9/ yr。此外，还测定了Hf/Lu丰度比。
The capture cross sections of /sup 138/Ba, /sup 140,142/Ce, /sup 176/Lu, /sup 181/Ta and the capture cross section of /sup 175/Lu to the 3.68 h isomeric state in /sup 176/Lu have been determined at 30 keV neutron energy using the activation technique. Neutrons were generated via the /sup 7/Li( p,n) reaction just above the reaction threshold at a 3 MV pulsed Van de Graaff accelerator. The capture cross sections are of importance to stellar nucleosynthesis. With the /sup 138/Ba and /sup 140/Ce cross sections the time integrated average neutron flux for the s process was determined to 0.22 mb/sup -1/. This result, the capture cross section of /sup 176/Lu and the /sup 175/Lu cross section to the 3.68 h isomeric state in /sup 176/Lu were used to analyze the /sup 176/Lu cosmic clock. The mean s process age of solar matter before the solidification of the solar system was estimated to 6 x 10/sup 9/ yr. In addition the Hf/Lu abundance ratio was determined.