Observation of M3 isomeric transition from 156mPm through the βdecay of 156Nd

Abstract

An M3 transition in a doubly odd nucleus of 156 Pm was identified by internal conversion electron measurement through the β-decay of 156 Nd which was separated from the fission products of 235 U using the on-line mass separator KUR-ISOL. The isomeric state at 150.3 keV de-excites to the ground state with the M3 transition, and the spin-parity is considered to be 1 −. Nilsson configurations are also discussed on the basic of the systematics.

Deformed band structures in neutron-rich Pm152–158 isotopes

“…Pm nuclei, with a wide isotopic range, are good candidates to explore the evolution of deformation with neutron number and possible role of octupole deformation in this region. It may be noted that there are no stable isotopes of Pm and that the isotopes beyond 151 Pm are known only through radioactive decay studies [18][19][20][21][22][23], proton transfer measurements [24,25] and spontaneous fission of 252 Cf source [26]. This is mainly due to non-availability of suitable target-projectile combination to produce the nuclei in fusion evaporation reaction with large cross section.…”

Structure of the yrast band in the odd-odd deformed nucleusPm156

“…The source reference quoted therein for this statement is Greenwood et al [1], which is a compilation of β-decay data for several radionuclides from 252 Cf spontaneous fission; however, it does not include any data for 156 Nd decay. The closest γ energy to the 85.6(3) keV transition of Hwang et al [8] is that of a very intense 84.7(1) keV γ seen in 156 Nd decay [3,10,16,17]; clearly, there is no overlap between the energies of these two transitions. The 85.6(3) keV transition in 156 Pm reported, alongside six other γ 's, by Hwang et al [8], does not match any γ so far reported from 156 Nd β decay.…”

“…Considering that these n-rich nuclides quickly undergo sequential β decays, studies of level structures of specified individual nuclides require an on-line mass-separator (ISOL) facility along with a sophisticated detector system [1][2][3][4]. Alternatively, γ -ray spectroscopy of secondary fission fragments has been pursued using large arrays of Compton-suppressed Ge detectors providing access to yrast or near-yrast structures [5,6].…”

“…and its 150.3 keV isomer identified in β decays of 156 Pm [2,10] and 156 Nd [3]. The analysis involved the mapping of the configuration space around the Fermi surface using experimental inputs on locations of neutron and proton Nilsson orbitals in the adjacent isotone and isotope, and also taking into account the Gallagher-Moszkowski (GM) coupling rule [11] and the rotor particle model [12] applicable to odd-odd deformed nuclei.…”

Configuration and bandhead spin assignments for the two-quasiparticle rotational bands in the neutron-rich nuclei Pm154,156

“…Recently, high-spin structures in the neutron-rich 152−158 Pm isotopes, including both odd-A and odd-odd nuclei, have been observed experimentally by the spontaneous fission of the actinide nuclei [13]. Compared with pervious experiments [14][15][16][17][18][19][20], these rotational bands either have been obtained for the first time, or have been extended considerably to higher spins. Unfortunately, these experimental data do not show any evidence of existing of octupole deformation in these Pm isotopes with neutron number N > 90.…”