β-decay measurements forN>40Mn nuclei and inference of collectivity for neutron-rich Fe isotopes

Low-energy structure of2766Co39and2768CoLiddick1, Abromeit2, Ayres3 et al. 2012Phys. Rev. CSelf Cite275291View full textAdd to dashboardCite

“…Such behavior is not completely unexpected given the rapid development of collectivity in other regions with the addition or subtraction of a few nucleons [5,6]. Within the N =40 region, the influence of the neutron g 9/2 , and to a lesser extent the d 5/2 , singleparticle states on the development of collectivity has been explored theoretically [7][8][9][10] and compared to a wealth of experimental signatures in the 24 Cr, 25 Mn, 26 Fe, and 27 Co isotopic chains. The systematics of the E(2 + 1 ) states in both Fe and Cr isotopes do not display a peak at N = 40 [11,12] but monotonically decrease in energy starting at N = 36 and N = 32, respectively.…”

Shape coexistence alongN=40

“…Contrary to simple expectations when bridging the N = 40 gap, the ground states of 65 Fe and 67 Fe are tentatively assigned 1/2 − spins and parities [27,28]. The 1/2 − ground-state spin and parity assignment of 67 Fe was explained using a deformation of ∼0.2 [11]. Referring to Fig.…”

“…Accumulated experimental data on nuclei in the vicinity of 68 Ni has since shown the N = 40 gap to be quite fragile [8][9][10]. Furthermore, evidence for the increasing influence of the intruder neutron g 9/2 single-particle state and the development of deformation has accumulated in the Fe and Mn isotopes [11][12][13][14]. Large-scale shell-model calculations along N = 40 near 68 Ni have had success interpreting even-even nuclei in this region and suggest a sharp transition from spherical to prolate deformed nuclei with the removal of two protons from 68 Ni to 66 Fe [15].…”

“…The ground states in both 65 Fe and 67 Fe are attributed to filling the K = 1/2 − level, suggesting small changes occur to the energy separation between the νp 1/2 and νf 5/2 single-particle states between N = 39 and N = 41. Further, based on half-life considerations for the unobserved isomeric level in 67 Fe, an assignment of 9/2 + [29] was excluded in favor of a 5/2 + spin and parity due to the K = 5/2 + level of the neutron g 9/2 single-particle state [11].…”

β−decay of65Mn to65Fe

“…A 420(13)-ns isomer was identified at 396.8 keV, which feeds the 363.3(5)-keV level by a 33.5(5)-keV transition [18][19][20]. The 33.5-keV transition was assigned as E1 [21] although no evidence was provided.…”