Submicrosecond isomer in45117Rh72and the role of triaxiality in its electromagnetic decay rate

Abstract

The neutron-rich nucleus 117 Rh was synthesized in the fission of relativistic 238 U beam produced at the GSI laboratory in Darmstadt, Germany. An isomeric state with t 1/2 = 138(17) ns decaying by a single γ-ray was observed, providing the first information on the excited states in this nucleus. The experimental data is discussed in terms of systematics and interpreted by using Woods-Saxon deformed shell model and Triaxial-Rotor-plus-Particle calculations. The origin of the isomer is explained as being due to a hindered E2 transition to the ground state.

Excited levels in the multishaped Pd117 nucleus studied via β decay of Rh117

“…Prolate-type deformation is predicted for ground states and an oblate-type for the isomers in Pd isotopes [59,60]. Deformed shell-model calculations for eveneven palladium isotopes [1] predict quadrupole deformation with β 2 > 0.2.…”

“…Consequently the β feeding values observed in this work, which are shown in Table II The knowledge of the spin parity of the ground state of 117 Rh is of prime importance for assigning spins and parities to levels in 117 Pd, populated in the β decay of 117 Rh. An axially asymmetric deformation is proposed for rhodium isotopes to explain the nuclear structure observed in spectroscopy measurements [1,38,39]. Theoretical calculations of the potential-energy surface for 117 Rh, based on the FRLDM macroscopic-microscopic model, show a single minimum for the axial-asymmetry coordinate γ ≈ 45…”

“…The levels and transitions in 117 Pd, populated in the β − decay of 117 Rh, currently represents the most rich spectroscopy information at the neutron-rich side of the A = 117 isobaric chain. In the next more exotic nucleus 117 Rh, there is only one excited level known, a submicrosecond isomer, which decays by a single γ ray of 321 keV [1].…”

β -decay rates of Rh115,117 into Pd115Ferretti1, Kotila2, Vsevolodovna3 et al. 2020Phys. Rev. C11021View full textAdd to dashboardCite

“…is the fermion single-particle matrix element, where g and g s are the single- In what follows, we use our IBFM-2 predictions for M1 transitions to discuss the J P quantum number assignments for the 115,117 Pd ground states; the experimental data can be found in Refs. [20,21,23,29,32,[59][60][61]. This critical analysis can be useful due to the conflicting nature of the previous experimental results.…”

New insights into triaxiality and shape coexistence from odd-mass Rh109

“…For higher Z (≥42), the evolution of structure and shape coexistence becomes less clear, however it is well known that axial asymmetry begins to play an important role in the low-energy structure [16,24,34,[39][40][41][42][43][44][45][46][47].…”