热核物质中12C,16O激发态α团簇性质研究及其在天体物理中的应用

3α过程和12C(α,γ)16O反应在恒星氦燃烧过程中最为关键的反应，不仅决定恒星中C,O丰度比，也影响大质量恒星演化与结构以及核合成过程。恒星热核反应中的等离子体效应是核天体物理学的重要研究课题。针对恒星等离子体中核物质对3α过程和12C(α,γ)16O反应的影响依赖12C,16O近阈(7.27MeV,7.16MeV)激发态性质这一关键科学问题，基于前期积累的关于恒星Li丰度问题和12C激发态团簇性质研究，本申请项目拟利用兰州重离子加速器开展15MeV/u的40Ca+12C反应实验测量，研究热核物质中的12C,16O激发态α团簇性质及其对3α过程和12C(α,γ)16O反应的影响。同时，收集现有数据，结合本项目实验与理论计算进行细致的天体核数据评价。利用MESA程序计算大质量恒星演化与核合成，进一步弄清新评价的核数据对弱s-过程核合成元素丰度的影响。

3α process and 12C(α,γ)16O reactions play important role in the stellar helium burning process. They determine the relative stellar abundance of C,O and have significant effects on subsequent stellar evolution and structure and on the resulting nucleosynthesis. Study of the plasma effects to the stellar thermal nuclear reaction is the important research topic in nuclear astrophysics. The nuclear matter of stellar plasma effects to the 3α and 12C(α,γ)16O reactions depend on 12C,16O excited states close to the threshold. In this proposal, the nuclear reaction of 40Ca+12C at 15MeV/u will be experimentally measured in order to investigate the α cluster properties of 12C,16O excited states in hot nuclear matter and their impacts on 3α process and 12C(α,γ)16O reactions, based on the previous studies about stellar Li abundance problem and cluster property of 12C excited states. Meanwhile, the detailed nuclear data evaluations will be studied with collection of the existing data coupled with the present experiment and calculations. Massive star evolution and nucleosynthesis calculations will be performed with MESA code for making clear the effects of newly evaluated nuclear data on weak s-process nucleosynthesis element abundance.