First Application of Mass Measurements with the Rare-RI Ring Reveals the Solar r-Process Abundance Trend at A=122 and A=123.-猫眼课题宝

DOI：

10.1103/physrevlett.128.152701

发表时间：

2021-12

期刊：

Physical review letters

影响因子：

8.6

通讯作者：

中科院分区：

物理与天体物理1区

文献类型：

作者：

H. F. Li-H. F.-Li-2162729369;S. Naimi;T. Sprouse;M. Mumpower;Y. Abe;Y. Yamaguchi;D. Nagae;F. Suzaki;M. Wakasugi;H. Arakawa;W. B. Dou;D. Hamakawa;S. Hosoi;Y. Inada;D. Kajiki;T. Kobayashi;M. Sakaue;Y. Yokoda;T. Yamaguchi;R. Kagesawa;D. Kamioka;T. Moriguchi;M. Mukai;A. Ozawa;S. Ota;N. Kitamura;S. Masuoka;S. Michimasa;H. Baba;N. Fukuda;Y. Shimizu;H. Suzuki;H. Takeda;D. Ahn;M. Wang;C. Fu;Q. Wang;S. Suzuki;Z. Ge;Y. Litvinov;G. Lorusso;P. M. Walker;Z. Podolyák;T. Uesaka

Rare-RI Ring （R3）是RIKEN放射性同位素束流工厂（RIBF）最近投入使用的一种类似回旋加速器的存储环质谱仪，专门用于测量远离稳定的外来核的质量。报道了R3质谱计在RIBF的首次应用。在R3中注入RIBF生成的稀有同位素-^{127}Sn、^{126}In、^{125}Cd、^{124}Ag、^{123}pd。测量了^{126}In、^{125}Cd和^{123}Pd的质量，从而提高了^{123}Pd的质量不确定度。这是首次报道在重离子回旋加速器上实现的新的存储环质谱技术，并采用预先识别的稀有原子核的单独注射。后者对于RIBF生产的最稀有同位素的未来质量测量至关重要。通过对具有不同电子分数Y_{e}的20个轨道进行反应网络计算，研究了新的^{123}Pd结果对中子星合并事件中太阳r过程丰度的影响。结果表明，^{123}Pd上的中子俘获截面增加了2.2倍，^{123}Rh上的β-延迟中子发射概率P_{1n}增加了14%。^{122}Pd上的中子俘获截面减小了2.6倍，导致物质在a =122处堆积，从而再现了太阳r过程丰度的趋势。研究了钯同位素链的双中子分离能（S_{2n}）的变化趋势。改进了不确定度的新质量测量排除了N=77时S_{2n}值的大变化。在N=82之前，S_{2n}值的大幅增加被认为可以替代N=82壳隙的淬火，以在A=112-124的质量区域重现r-过程丰度。

The Rare-RI Ring (R3) is a recently commissioned cyclotronlike storage ring mass spectrometer dedicated to mass measurements of exotic nuclei far from stability at Radioactive Isotope Beam Factory (RIBF) in RIKEN. The first application of mass measurement using the R3 mass spectrometer at RIBF is reported. Rare isotopes produced at RIBF-^{127}Sn, ^{126}In, ^{125}Cd, ^{124}Ag, ^{123}Pd-were injected in R3. Masses of ^{126}In, ^{125}Cd, and ^{123}Pd were measured whereby the mass uncertainty of ^{123}Pd was improved. This is the first reported measurement with a new storage ring mass spectrometry technique realized at a heavy-ion cyclotron and employing individual injection of the preidentified rare nuclei. The latter is essential for the future mass measurements of the rarest isotopes produced at RIBF. The impact of the new ^{123}Pd result on the solar r-process abundances in a neutron star merger event is investigated by performing reaction network calculations of 20 trajectories with varying electron fraction Y_{e}. It is found that the neutron capture cross section on ^{123}Pd increases by a factor of 2.2 and β-delayed neutron emission probability, P_{1 n}, of ^{123}Rh increases by 14%. The neutron capture cross section on ^{122}Pd decreases by a factor of 2.6 leading to pileup of material at A=122, thus reproducing the trend of the solar r-process abundances. The trend of the two-neutron separation energies (S_{2n}) was investigated for the Pd isotopic chain. The new mass measurement with improved uncertainty excludes large changes of the S_{2n} value at N=77. Such large increase of the S_{2n} values before N=82 was proposed as an alternative to the quenching of the N=82 shell gap to reproduce r-process abundances in the mass region of A=112-124.

First Application of Mass Measurements with the Rare-RI Ring Reveals the Solar r-Process Abundance Trend at A=122 and A=123.

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