Negative parity bands ofPd115and band structures inPd113,115

Abstract

Level structures of 113,115,117 Pd have been studied using the Gammasphere and a spontaneous fission source of 252 Cf. A new 85.1-keV transition was identified in 113 Pd. This indicates that the spin and parity of the isomeric state is 9/2 − rather than the previously assigned 11/2 − . New low-energy transitions are confirmed in 115,117 Pd. In 115 Pd, the 39.0.-and 49.0-keV transitions are shown to be in prompt coincidence. This coincidence relationship indicates a spin and parity assignment of 1/2 + for the ground state rather than the previously assigned 3/2 + .

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

“…[37]. Total intensity of 17.8 keV was estimated as 7 (3) Pd was confirmed in another study, using a 252 Cf spontaneous-fission source [9].…”

“…In the singles γ spectrum [see Fig. 2(a)] one observes, for the ion trap frequency set to 117 Rh, the 71.4-and 168.6-keV lines depopulating the isomer and the 63.3-keV line observed before in the spontaneous fission study [8,9]. The 63.3-keV line is not coincident with any other line in our β-decay data and this is why we think that it populates directly the 203.2-keV isomer.…”

“…In the chain of Pd isotopes a hint of a transition to the oblate regime was recently reported in 115 Pd [7] in connection with the new spin-parity assignment of 1/2 + to the ground state (g.s.) and of 7/2 − to the isomer in this nucleus [6,8,9]. Therefore, the extension of these studies to 117 Pd is a natural step towards the identification of an oblate deformation, which is still a rare phenomenon in nuclei.…”

“…[2] Skalski et al pointed to strong shape variations due to the predicted coexistence of prolate and oblate potential minima and a γ softness expected in Mo-Pd nuclei. Many examples of these phenomena have been observed experimentally in the 100 < A < 120 region, especially effects related to γ softness and triaxiality in neutron-rich Mo-Pd isotopes [4][5][6][7][8][9][10][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29].…”

“…In these early works, it was assumed that in all these Pd isotopes spins of isomeric levels were 11/2 − , corresponding to the spherical νh 11/2 excitation. Subsequent changes of some of these assignments [5,6,9] have shed new light on the effect. It is of interest to check whether any further changes in spin-parity assignments should be made in these isotopes, especially in 117 Pd.…”