准自由中子敲出反应揭示了硼烷核$^{17}B$中的一个小$s$轨道成分。

Quasifree Neutron Knockout Reaction Reveals a Small s-Orbital Component in the Borromean Nucleus ^{17}B.

作者信息

Yang Z H, Kubota Y, Corsi A, Yoshida K, Sun X-X, Li J G, Kimura M, Michel N, Ogata K, Yuan C X, Yuan Q, Authelet G, Baba H, Caesar C, Calvet D, Delbart A, Dozono M, Feng J, Flavigny F, Gheller J-M, Gibelin J, Giganon A, Gillibert A, Hasegawa K, Isobe T, Kanaya Y, Kawakami S, Kim D, Kiyokawa Y, Kobayashi M, Kobayashi N, Kobayashi T, Kondo Y, Korkulu Z, Koyama S, Lapoux V, Maeda Y, Marqués F M, Motobayashi T, Miyazaki T, Nakamura T, Nakatsuka N, Nishio Y, Obertelli A, Ohkura A, Orr N A, Ota S, Otsu H, Ozaki T, Panin V, Paschalis S, Pollacco E C, Reichert S, Roussé J-Y, Saito A T, Sakaguchi S, Sako M, Santamaria C, Sasano M, Sato H, Shikata M, Shimizu Y, Shindo Y, Stuhl L, Sumikama T, Sun Y L, Tabata M, Togano Y, Tsubota J, Xu F R, Yasuda J, Yoneda K, Zenihiro J, Zhou S-G, Zuo W, Uesaka T

机构信息

Research Center for Nuclear Physics (RCNP), Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.

RIKEN Nishina Center, Hirosawa 2-1, Wako, Saitama 351-0198, Japan.

出版信息

Phys Rev Lett. 2021 Feb 26;126(8):082501. doi: 10.1103/PhysRevLett.126.082501.

DOI:10.1103/PhysRevLett.126.082501

PMID:33709737

Abstract

A kinematically complete quasifree (p,pn) experiment in inverse kinematics was performed to study the structure of the Borromean nucleus ^{17}B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for 1s_{1/2} and 0d_{5/2} orbitals, and a surprisingly small percentage of 9(2)% was determined for 1s_{1/2}. Our finding of such a small 1s_{1/2} component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in ^{17}B. The present work gives the smallest s- or p-orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of s or p orbitals is not a prerequisite for the occurrence of a neutron halo.

摘要

为了研究长期以来被认为具有中子晕的硼同位素核(^{17}B)的结构，进行了一次运动学完备的逆运动学准自由((p,pn))实验。通过分析动量分布和排他性截面，我们得到了(1s_{1/2})和(0d_{5/2})轨道的光谱因子，并且确定(1s_{1/2})的比例小得出奇，仅为(9(2)%)。我们发现如此小的(1s_{1/2})成分以及先前实验中报道的晕特征，可以用连续介质中的变形相对论Hartree-Bogoliubov理论来解释，这揭示了(^{17}B)中存在确定但不占主导地位的中子晕。本工作给出了已知具有晕特征的原子核中最小的(s)或(p)轨道成分，并表明(s)或(p)轨道的主导占据并非中子晕出现的先决条件。