Collective features of Cr and Fe isotopes

Abstract

The question of the sudden increase of collectivity in neutron-rich nuclei when approaching N = 40 has recently interested both experimentalists and theorists. In this paper we study the development of collectivity along the chromium and iron isotopic chains. The calculations are performed within two different perspectives, namely, the proton-neutron interacting boson model (IBM-2) and interacting shell model (ISM) and compared with the available experimental data. The onset of collectivity is studied through nuclear quantities and observables that suggest differences in the nuclear structure of Cr and Fe isotopical chains. Furthermore, a prediction for the shape transition from a spherical vibrator to γ -soft rotor with nucleus 58 Cr standing at the critical point is discussed.

Reduced transition strengths of low-lying yrast states in chromium isotopes in the vicinity ofN=40

“…The values are compared to former experimental results taken from Coulomb excitation experiments at intermediate energies [23,54]. In addition, the results are compared to calculations performed with the shell model using the LNPS interaction [27] and the proton-neutron version of the interacting boson model (IBM-2) [32]. The present B(E2; 2 + 1 → 0 + 1 ) values in 58,60,62 Cr are in agreement with previous results [23,54].…”

“…By including the neutron 0g 9/2 and 1d 5/2 orbitals in the valence space, calculations within the spherical shell model formalism using the LNPS interaction [27] are able to reproduce the rapidly evolving quadrupole collectivity in neutron-rich Fe and Cr isotopes. Shell model calculations in a large model space using realistic interactions [31] and calculations with the proton-neutron version of the interacting boson model (IBM-2) were performed recently [32]. In general, the available experimental information in neutron-rich Cr isotopes with A ≥ 58 is sparse.…”

Nuclear matrix elements for double-βdecay

“…4 Dy have just been published [108]. A paper with those for 48 Ti is in preparation [109]. The quality of these, as well as of the unpublished results for 96 Zr is equal to that of the results obtained previously [95][96][97][98][99][100][101][102][103][104][105][106][107].…”

New limits on double electron capture of40Ca and180W

“…In this paper, we derive experimental limits on the half-lives of 2ν2EC and 0ν2EC processes for 40 Ca and 180 W. The latter is one of the best candidates to observe resonant 0ν2EC [5,16]. A summary of the processes studied in this work is shown in table 1.…”