原子能科学技术2026，Vol.60Issue(8)：1548-1554,7.DOI:10.7538/yzk.2025.youxian.0744
γ-过程139La(γ,n)138La天体反应率研究
Investigation of 139La(γ,n)138La Reaction Rates for Astrophysical γ-process
摘要
Abstract
The synthesis of heavy elements beyond the iron peak remains a partially unresolved problem in nuclear astrophysics.About 99%of these heavy nuclei are produced via the slow and rapid neutron-capture processes.A small fraction of neutron-deficient isotopes are bypassed by them.These approximately 35 proton-rich nuclei,ranging in mass from Se to Hg,are known as the p-nuclei.Based on current models,the majority of p-nuclei is synthesized via photodisintegration reactions in the so-called γ-process,which occurs within the O/Ne-rich burning shells of core-collapse supernovae.The passage of the shock front through these layers induces a transient heating to temperatures between 2.0 and 3.5 GK,allowing the partial photodisintegration of pre-existing seed nuclei.In any case,network calculations are essential for reproducing p-nuclei abundances,requiring a network including nearly 20 000 nuclear reactions of almost 2 000 nuclei in the Ni-Bi region.The γ-process relies heavily on the Hauser-Feshbach(HF)statistical model and the various nuclear ingredients in such a framework.In reality,it remains a challenge to validate the reliability of the HF model and its inputs,and accordingly to put the γ-process calculations on a more reliable base.Therefore,it is imperative to constrain the HF models using the experimental data.Despite the success of the γ-process in explaining most p-nuclei,the origin of the 138La remains a key unresolved question in nucleosynthesis.138La is underproduced in all γ-process calculations performed so far.The low abundance of 138La has prompted the investigation of non-thermonuclear process.Although the νₑ capture on 138Ba has been shown to be the most efficient mechanism for producing solar 138La,a substantial thermonuclear origin cannot be excluded.This would require that the protosolar nebula was enriched in p-nuclei by sources other than typeⅡsupernovae.In particular,sub-Chandrasekhar mass white dwarf explosions are considered potential significant contributors.The thermonuclear origin of 138La critically depends on the competition between its production via 139La(γ,n)and its destruction via 138La(n,γ).To investigate the contribution of the γ-process to 138La production,a comprehensive illustration of constraining the HF theoretical models was presented using the 139La(γ,n)138La experimental data,and the most influential nuclear models were identified.The optimized models can be employed to evaluate the plasma reaction rates of the 139La(γ,n)138La.The extracted reaction rates of 139La(γ,n)138La were also compared with those from the JINA reaction library.Our recommended rate is more than a factor of two higher than that in the JINA at 2.5 GK.Such a discrepancy has the potential to partially mitigate the underproduction of 138La.关键词
TALYS 2.0/光核反应/天体反应率Key words
TALYS 2.0/photonuclear reaction/astrophysical reaction rate分类
数理科学引用本文复制引用
杨畅,程浩,叶杉,董秉坤,卢牧阳,徐永生,刘伏龙,贺创业,郭冰..γ-过程139La(γ,n)138La天体反应率研究[J].原子能科学技术,2026,60(8):1548-1554,7.基金项目
国家自然科学基金(U2441221,12305149,12205378) （U2441221,12305149,12205378）
中核集团"青年英才"项目(FY010260623371) （FY010260623371）
中核集团基础研究项目(FK010271224841) （FK010271224841）
国家重点研发计划(2022YFA1602403) （2022YFA1602403）
核数据重点实验室基金(6142A082024-4) （6142A082024-4）
稳定支持基础科研计划(18BJ010261224900) （18BJ010261224900）
中国原子能科学研究院核物理研究所所长基金(PA010271225775) （PA010271225775）
