Neutron-unbound states in Ne31
Neutron-unbound states in Ne31
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Ne31 中的中子游离态
DOI：
10.1103/physrevc.104.034313
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发表时间：
2021
影响因子：
3.1
通讯作者：
Frank, N.
中科院分区：
文献类型：
--
作者：
Chrisman, D.;Kuchera, A. N.;Baumann, T.;Blake, A.;Brown, B. A.;Brown, J.;Cochran, C.;DeYoung, P. A.;Finck, J. E.;Frank, N.
背景：与球壳模型相比，壳间隙附近的反转岛是单粒子能级重新排序的核的所在地。研究表明，它的基态有一个晕成分，其特征是价中子绕变形核心运行。这种分离能仅为 keV 的轻束缚核预计具有中子未束缚的激发态。目的：本实验的目的是研究单个中子发射衰变中的低激发态。方法：89 MeV/核子束撞击分段 Be 反应靶。通过二质子敲除反应形成中子未束缚态。国家超导回旋加速器实验室的 MoNA-LISA-Sweeper 实验装置检测到了衰变产生的碎片和相关中子。使用不变质谱重建二体衰变能（）。结果：二体衰变能谱表现出两个特征：MeV处的低峰和MeV处的广泛增强，每个特征都符合能量相关的不对称Breit-Wigner线形，代表连续谱中的共振。使用 NuShellX 内的 FSU 相互作用进行的壳模型计算，结合使用 Ekonal 反应理论的横截面计算，表明衰变能谱中的这些峰是由多个共振态引起的。结论：首次观察到激发态。从计算的壳模型最终状态到束缚态的转变与测量的衰变能谱非常一致。使用两个质子敲除填充态的横截面计算以及与 的衰变相关的光谱因子来检查壳模型期望范围内的结果。
Background:The island of inversion near theshell gap is home to nuclei with reordered single-particle energy levels compared with the spherical shell model. Studies ofhave revealed that its ground state has a halo component characterized by a valence neutron orbiting a deformedcore. This lightly bound nucleus with a separation energy of onlykeV is expected to have excited states that are neutron unbound.Purpose:The purpose of this experiment was to investigate the low-lying excited states inthat decay by the emission of a single neutron.Methods:An 89 MeV/nucleonbeam impinged on a segmented Be reaction target. Neutron-unbound states inwere populated via a two-proton knockout reaction. Thefragment and associated neutron from the decay ofwere detected by the MoNA-LISA-Sweeper experimental setup at the National Superconducting Cyclotron Laboratory. Invariant-mass spectroscopy was used to reconstruct the two-body decay energy ().Results:The two-body decay energy spectrum exhibits two features: a low-lying peak atMeV and a broad enhancement atMeV, each fit with an energy-dependent asymmetric Breit-Wigner lineshape representing a resonance in the continuum. Accompanying shell-model calculations using the FSU interaction withinNuShellX, combined with cross-section calculations using the eikonal reaction theory, indicate that these peaks in the decay energy spectrum are caused by multiple resonant states in.Conclusions:Excited states inwere observed for the first time. Transitions from calculated shell-model final states into bound states inare in good agreement with the measured decay energy spectrum. Cross-section calculations for the two-proton knockout populatingstates as well as spectroscopic factors pertaining to the decay ofintoare used to examine the results within the context of the shell-model expectations.