Restoration of the natural E(1/21+) - E(3/21+) energy splitting in odd-K isotopes towards N = 40

• DOI: 10.1016/j.physletb.2020.135215
• Publication Date: 2020-01-16T11:30:42Z
• Authors: Y.L. Sun; A. Obertelli; P. Doornenbal; C. Barbieri; Y. Chazono; T. Duguet; H.N. Liu; P. Navrátil; F. Nowacki; K. Ogata; T. Otsuka; F. Raimondi; V. Somà; Y. Utsuno; K. Yoshida; N. Achouri; H. Baba; F. Browne; D. Calvet; F. Château; S. Chen; N. Chiga; A. Corsi; M.L. Cortés; A. Delbart; J.-M. Gheller; A. Giganon; A. Gillibert; C. Hilaire; T. Isobe; T. Kobayashi; Y. Kubota; V. Lapoux; T. Motobayashi; I. Murray; H. Otsu; V. Panin; N. Paul; W. Rodriguez; H. Sakurai; M. Sasano; D. Steppenbeck; L. Stuhl; Y. Togano; T. Uesaka; K. Wimmer; K. Yoneda; O. Aktas; T. Aumann; L.X. Chung; F. Flavigny; S. Franchoo; I. Gašparić; R.-B. Gerst; J. Gibelin; K.I. Hahn; D. Kim; T. Koiwai; Y. Kondo; P. Koseoglou; J. Lee; C. Lehr; B.D. Linh; T. Lokotko; M. MacCormick; K. Moschner; T. Nakamura; S.Y. Park; D. Rossi; E. Sahin; D. Sohler; P.-A. Söderström; S. Takeuchi; H. Törnqvist; V. Vaquero; V. Wagner; S. Wang; V. Werner; X. Xu; H. Yamada; D. Yan; Z. Yang; M. Yasuda; L. Zanetti
• Keywords: CHARGE RADII; QC1-999; Shell evolution; [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]; Astronomy & Astrophysics; 530; Spectroscopy ; Shell evolution ; 51K ; 53K; 01 natural sciences; Physics, Particles & Fields; Spectroscopy; Shell evolution; 51K; 53K; K-51; 0103 physical sciences; K-53; Spectroscopy; 53K; Science & Technology; 51K; NUCLEI; HOLE STATES; Physics; 540; Physics, Nuclear; Physical Sciences; SHELL-MODEL; 53 K; 51 K

We report on the first γ -ray spectroscopy of 51, 53 K produced via the 52, 54 Ca( p , 2 p ) reactions at ∼250 MeV/nucleon. Unambiguous final-state angular-momentum assignments were achieved for beam intensities down to few particles per second by using a new technique based on reaction vertex tracking combined with a thick liquid-hydrogen target. Through γ -ray spectroscopy and exclusive parallel momentum distribution analysis, 3/2 + ground states and 1/2 + first excited states in 51, 53 K were established quantifying the natural ordering of the 1d3/2 and 2s1/2 proton-hole states that are restored at N = 32 and 34. State-of-the-art ab initio calculations and shell-model calculations with improved phenomenological effective interactions reproduce the present data and predict consistently the increase of the E (1/2 1+ ) - E (3/2 1+ ) energy differences towards N = 40.