Hoff D E M, Kolos K, Misch G W, Ray D, Liu B, Valverde A A, Brodeur M, Burdette D P, Callahan N, Clark J A, Gallant A T, Kondev F G, Morgan G E, Mumpower M R, Orford R, Porter W S, Rivero F, Savard G, Scielzo N D, Sharma K S, Sieja K, Sprouse T M, Varriano L
Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Phys Rev Lett. 2023 Dec 29;131(26):262701. doi: 10.1103/PhysRevLett.131.262701.
Nuclear isomer effects are pivotal in understanding nuclear astrophysics, particularly in the rapid neutron-capture process where the population of metastable isomers can alter the radioactive decay paths of nuclei produced during astrophysical events. The β-decaying isomer ^{128m}Sb was identified as potentially impactful since the β-decay pathway along the A=128 isobar funnels into this state bypassing the ground state. We report the first direct mass measurements of the ^{128}Sb isomer and ground state using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. We find mass excesses of -84564.8(25) keV and -84608.8(21) keV, respectively, resulting in an excitation energy for the isomer of 43.9(33) keV. These results provide the first key nuclear data input for understanding the role of ^{128m}Sb in nucleosynthesis, and we show that it will influence the flow of the rapid neutron-capture process.
核同质异能素效应对于理解核天体物理学至关重要，特别是在快速中子俘获过程中，亚稳态同质异能素的丰度可以改变天体物理事件中产生的原子核的放射性衰变路径。β衰变同质异能素(^{128m}Sb)被认为具有潜在影响，因为沿着(A = 128)同量异位素的β衰变路径会绕过基态而汇聚到这个状态。我们报告了使用阿贡国家实验室的加拿大潘宁阱质谱仪对(^{128}Sb)同质异能素和基态进行的首次直接质量测量。我们分别发现质量过剩为(-84564.8(25))keV和(-84608.8(21))keV，从而得出同质异能素的激发能为(43.9(33))keV。这些结果为理解(^{128m}Sb)在核合成中的作用提供了首个关键的核数据输入，并且我们表明它将影响快速中子俘获过程的进程。
