Sun, Y.L. ; Obertelli, A. ; Doornenbal, P. ; Barbieri, C. ; Chazono, Y. ; Duguet, T. ; Liu, H.N. ; Navrátil, P. ; Nowacki, F. ; Ogata, K. et al.
Restoration of the natural E(1/2 1 + ) – E(3/2 1 + ) energy splitting in odd-K isotopes towards N = 40
PHYSICS LETTERS B 802 Paper: 135215 , 7 p. (2020)
Published: 10 March 2020
We report on the first γ-ray spectroscopy of 51,53K produced via the 52,54Ca(p,2p) 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 51,53K were established quantifying the natural ordering of the and proton-hole states that are restored at N = 32 and 34. State-of-the-art ab initiocalculations and shell-model calculations with improved phenomenological effective interactions reproduce the present data and predict consistently the increase of the E(1/2) – E(3/2) energy differences towards N = 40.