CERN Accelerating science

Preprint
Report number	arXiv:2409.07324
Title	$^{61}$Cr as a Doorway to the $N = 40$ Island of Inversion
Author(s)	Lalanne, L. (Leuven U. ; CERN ; Strasbourg, IPHC) ; Athanasakis-Kaklamanakis, M. (Leuven U. ; CERN) ; Dao, D.D. (Strasbourg, IPHC) ; Koszorús, Á. (Leuven U.) ; Liu, Y.C. (Peking U., SKLNPT) ; Mancheva, R. (Leuven U. ; CERN) ; Nowacki, F. (Strasbourg, IPHC) ; Reilly, J. (Manchester U.) ; Bernerd, C. (CERN) ; Chrysalidis, K. (CERN) ; Cocolios, T.E. (Leuven U.) ; de Groote, R.P. (Leuven U.) ; Flanagan, K.T. (Manchester U.) ; Garcia Ruiz, R.F. (MIT) ; Hanstorp, D. (U. Gothenburg (main)) ; Heinke, R. (Leuven U.) ; Heines, M. (Leuven U.) ; Lassegues, P. (Leuven U.) ; Mack, K. (Manchester U.) ; Marsh, B.A. (CERN) ; McGlone, A. ; Lynch, K.M. ; Neyens, G. (Leuven U.) ; Borne, B. van den (Leuven U.) ; Van Duyse, R. (Leuven U.) ; Yang, X.F. (Peking U., SKLNPT) ; Wessolek, J. (CERN ; Manchester U.)
Imprint	2024-09-11
Number of pages	6
Subject category	nucl-th ; Nuclear Physics - Theory ; nucl-ex ; Nuclear Physics - Experiment
Abstract	This paper reports on the measurement of the ground-state spin and nuclear magnetic dipole moment of $^{61}$Cr. The radioactive ion beam was produced at the CERN-ISOLDE facility and was probed using high-resolution resonance ionization laser spectroscopy with the CRIS apparatus. The present ground-state spin measurement $I = \frac{1}{2}$, differing from the previously adopted $I =(\frac{5}{2})$, has significant consequences on the interpretation of existing beta decay data and nuclear structure in the region. The structure and shape of $^{61}$Cr is interpreted with state-of-the-art Large-Scale Shell Model and Discrete-Non-Orthogonal Shell Model calculations. From the measured magnetic dipole moment $\mu(^{61}$Cr$)=+0.539(7) \mu_N$ and the theoretical findings, its configuration is understood to be driven by 2 particle - 2 hole neutron excitations with an unpaired $1p_{1/2}$ neutron. This establishes the western border of the $N=40$ Island Of Inversion (IoI), characterized by 4 particle - 4 hole neutron components. We discuss the shape evolution along the Cr isotopic chain as a quantum phase transition at the entrance of the $N=40$ IoI.
Other source	Inspire
Copyright/License	preprint: (License: CC BY-NC-SA 4.0)