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利用\(^{7}Be(d,p)^{8}Be^{*}\)中的共振激发解决宇宙锂问题

Resonance Excitations in ^{7}Be(d,p)^{8}Be^{*} to Address the Cosmological Lithium Problem.

作者信息

Ali Sk M, Gupta D, Kundalia K, Saha Swapan K, Tengblad O, Ovejas J D, Perea A, Martel I, Cederkall J, Park J, Szwec S

机构信息

Department of Physics, Bose Institute, 93/1 APC Road, Kolkata 700009, India.

Instituto de Estructura de la Materia-CSIC, Serrano 113 bis, ES-28006 Madrid, Spain.

出版信息

Phys Rev Lett. 2022 Jun 24;128(25):252701. doi: 10.1103/PhysRevLett.128.252701.

Abstract

The anomaly in lithium abundance is a well-known unresolved problem in nuclear astrophysics. A recent revisit to the problem tried the avenue of resonance enhancement to account for the primordial ^{7}Li abundance in standard big-bang nucleosynthesis. Prior measurements of the ^{7}Be(d,p)^{8}Be^{*} reaction could not account for the individual contributions of the different excited states involved, particularly at higher energies close to the Q value of the reaction. We carried out an experiment at HIE-ISOLDE, CERN to study this reaction at E_{c.m.}=7.8  MeV, populating excitations up to 22 MeV in ^{8}Be for the first time. The angular distributions of the several excited states have been measured and the contributions of the higher excited states in the total cross section at the relevant big-bang energies were obtained by extrapolation to the Gamow window using the talys code. The results show that by including the contribution of the 16.63 MeV state, the maximum value of the total S factor inside the Gamow window comes out to be 167 MeV b as compared to earlier estimate of 100 MeV b. However, this still does not account for the lithium discrepancy.

摘要

锂丰度异常是核天体物理学中一个著名的未解决问题。最近对该问题的重新审视尝试了共振增强途径,以解释标准大爆炸核合成中原始(^{7}Li)的丰度。先前对(^{7}Be(d,p)^{8}Be^{*})反应的测量无法解释所涉及的不同激发态的各自贡献,特别是在接近反应(Q)值的较高能量处。我们在欧洲核子研究中心的HIE - ISOLDE进行了一项实验,以研究在质心能量(E_{c.m.}=7.8) MeV下的该反应,首次使(^{8}Be)中的激发能达到22 MeV。测量了几个激发态的角分布,并使用talys代码外推到伽莫夫窗,从而获得了相关大爆炸能量下较高激发态在总截面中的贡献。结果表明,通过纳入16.63 MeV态的贡献,伽莫夫窗内总(S)因子的最大值为167 MeV·b,而早期估计值为100 MeV·b。然而,这仍然无法解释锂丰度的差异。

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