Development of Large Deformation inCr62

Abstract

The structure of neutron-rich isotopes 60Cr and 62Cr was studied via proton inelastic scattering in inverse kinematics. The deformation lengths (delta) for 60Cr and 62Cr were extracted as 1.12(16) and 1.36(14) fm, respectively, providing evidence for enhanced collectivity in these nuclei. An excited state at 1180(10) keV in 62Cr was identified for the first time. We adopted 4;{+} as its spin and parity, leading to the rapid increase of the Ex(4;{+})/E_{x}(2;{+}) ratio, which indicates the development of large deformation in 62Cr near N=40. Importance of the admixture of the gd-shell component above N=40 is also discussed by comparing with a modern shell model calculation.

Collective nature of low-lying excitations in70,72,74Zn from lifetime measurements using the AGATA spectrometer demonstrator

“…Recent shell model calculations using a larger valence space (pf shell for protons and pf 5/2 g 9/2 d 5/2 for neutrons with a 48 Ca core) [17] indicate an important role of the νd 5/2 orbital to describe the onset of collectivity below 68 Ni. Similar conclusions have been drawn from the spectroscopy of neutron-rich Cr isotopes [18,19] and are supported by recent mass measurements of heavy manganese isotopes [20]. A slightly increasing occupation of the νd 5/2 orbital in Fe isotopes with increasing neutron number is also predicted by beyond mean-field calculations [21], but remains small.…”

Single-particle and collective structures inCr55andV55Deacon1, Steppenbeck2, Zhu3 et al. 2011Phys. Rev. C11120View full textAdd to dashboardCite

“…The low-lying states of the even chromium isotopes exhibit first-excited state energies that are consistent with developing collectivity towards N = 40. Indeed, the development of large deformation in the low-lying states of 62 Cr is also evident in measurements of cross sections from proton inelastic scattering [19]. The recent extension of the knowledge of excited states to 64 Cr [20] displays a continued fall in the E(2 + 1 ) values and a corresponding rise in the ratio E(4 + 1 )/E(2 + 1 ) at N = 40, indicating the collective nature of these levels.…”

Collective features of Cr and Fe isotopes

“…This latter model space is also good enough to account for the spectroscopy of moderately neutron-rich Mn [37] isotopes. However, when approaching N = 40 these fpg calculations fail to describe the structure of neutron-rich nuclei, in particular, [60][61][62] Cr [6,8,38] and 66 Fe [23]. It is the inclusion of the neutron d 5/2 orbital which favors quadrupole correlations and the development of quadrupole collectivity in this mass region, as suggested already in Ref.…”

“…Unstable nuclei in this region exhibit many interesting phenomena such as the appearance of new magic numbers and the development of new regions of deformation for proton or neutron numbers that are magic near stability. In particular, for heavy Cr and Fe nuclei, there is a sudden increase in the collectivity approaching N = 40, as observed from the lowering of the energies of the 2 + 1 states and the sudden increase of the quadrupole transition probabilities to the ground state in the neutron-rich even-even isotopes [6][7][8][9][10][11][12][13][14].…”