NUCLEAR ASTROPHYSICS STUDIES WITH LASER INVERSE-COMPTON γ RAYS

利用激光反康普顿 γ 射线进行核天体物理研究

基本信息

批准号：
13640303
负责人：
UTSUNOMIYA Hiroaki
金额：
$ 0.45万
依托单位：
KONAN UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Quasi-monochromatic y rays produced from laser inverse-Compton scattering at AIST(National Institute of Advanced Industrial Science and Technology) were used to photo-disintegrate 1)^9Be of interest for nucleosynthesis in type II supernovae, 2)^<181>Ta for the p-process nucleosynthesis, 3)D for big bang nucleosynthesis, and 4) ^<186>W for the s-process nucleosynthesis. The following results were obtained.1)^9Be : Photoneutron cross sections were measured at energies from threshold to 6.1MeV. Electromagnetic reduced transition probabilities were determined for the 1/2^+,5/2^-,5/2^+ states in ^9Be and the astrophysical reaction rate for αα(n,γ)^9Be were evaluated.2)^<181>Ta : Photoneutron cross sections were measured at energies from threshold to 12MeV. The p-process origin of ^<180>Ta in O/Ne rich layers during explosions of massive stars as type II supernovae was discussed based on the Hauser-Feshbach model calculation with the QRPAγ strength function.3)D : Photoneutron cross sections were measured at energies from threshold to 4.6MeV. The reaction rate for p(n,γ)D was determined with 6% uncertainty in the energy region relevant to big bang nucleosynthesis, providing an experimental foundation for theoretical reaction rates.4)^<186>W : Photoneutron cross sections were measured at energies from threshold to 10.8MeV. Neutron-capture cross sections for a radioactive ^<185>W nucleus(T_<1/2>=75 days) were evaluated at 30keV using the Hauser-Feshbach statistical model. Constraints on neutron density allowed in s-process models were provided.

AIST（国家高级工业科学与技术研究所）产生的准单色射线用于拍照1）^9BE^9BE II型超级Novae的核旋转感兴趣，2）^<181> ta^<181> ta for p-Perocess osynthesis，for p-Perocess osynthesis，for for Big osynthesis，3） S过程的核相性。获得以下结果。1）^9BE：光线体横截面以从阈值到6.1Mev的能量测量。确定了^9BE中的1/2^+，5/2^ - ，5/2^+状态的电磁降低可能性，并评估了ααα（n，γ）^9BE的天体物理反应速率。2）^<181> ta：从theshold到12mev的能量，测量了在能量上的光线体交叉截面。在大规模恒星爆炸期间， ^<180> ta的p-过程起源是根据QRPAγ强度函数的Hauser-Feshbach模型计算讨论了II型超新星。 p（n，γ）d的反应速率用与大爆炸核渗透相关的能量区域的6％不确定性确定，为理论反应速率提供了实验基础。4）^<186> w：从阈值到10.8mev的能量，在能量下测量了光线体横切。使用Hauser-Feshbach统计模型评估了放射性 ^<185> W核的中子捕获横截面（T_ <1/2> = 75天）。提供了S过程模型中允许的中子密度的约束。