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

Z.H. Yang , Y. Kubota , A. Corsi (1) , K. Yoshida , X.-X. Sun , J.G. Li , M. Kimura , N. Michel , K. Ogata , C.X. Yuan , Q. Yuan , G. Authelet (1) , H. Baba , C. Caesar , D. Calvet (1) , A. Delbart (1) , M. Dozono , J. Feng , F. Flavigny (2) , J.-M. Gheller (1) , J. Gibelin (3) , A. Giganon (1) , A. Gillibert (1) , K. Hasegawa , T. Isobe , Y. Kanaya , S. Kawakami , D. Kim , Y. Kiyokawa , M. Kobayashi , N. Kobayashi , T. Kobayashi , Y. Kondo , Z. Korkulu , S. Koyama , V. Lapoux (1) , Y. Maeda , F.M. Marqués (3) , T. Motobayashi , T. Miyazaki , T. Nakamura , N. Nakatsuka , Y. Nishio , A. Obertelli (1) , A. Ohkura , N.A. Orr (3) , S. Ota , H. Otsu , T. Ozaki , V. Panin , S. Paschalis , E.C. Pollacco (1) , S. Reichert , J.-Y. Roussé (1) , A.T. Saito , S. Sakaguchi , M. Sako , C. Santamaria (1) , M. Sasano , H. Sato , M. Shikata , Y. Shimizu , Y. Shindo , L. Stuhl , T. Sumikama , Y.L. Sun (1) , M. Tabata , Y. Togano , J. Tsubota , F.R. Xu , J. Yasuda , K. Yoneda , J. Zenihiro , S.-G. Zhou , W. Zuo , T. Uesaka

1 DPHN - Département de Physique Nucléaire (ex SPhN)
2 IPNO - Institut de Physique Nucléaire d'Orsay
3 LPCC - Laboratoire de physique corpusculaire de Caen

A kinematically complete quasifree (p,pn) experiment in inverse kinematics was performed to study the structure of the Borromean nucleus B17, 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 1s1/2 and 0d5/2 orbitals, and a surprisingly small percentage of 9(2)% was determined for 1s1/2. Our finding of such a small 1s1/2 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 B17. 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.

Keywords: Nuclear Physics

Domains: Nuclear Experiment [nucl-ex]

Z.H. Yang, Y. Kubota, A. Corsi, K. Yoshida, X.-X. Sun, et al.. Quasifree Neutron Knockout Reaction Reveals a Small $s$-Orbital Component in the Borromean Nucleus $^{17}$B. Phys.Rev.Lett., 2021, 126 (8), pp.082501. ⟨10.1103/PhysRevLett.126.082501⟩. ⟨hal-03150577⟩