High-spin structures of 124−131Te: Competition of proton- and neutron-pair breakings

Abstract

The 124−131 Te nuclei have been produced as fission fragments in two fusion reactions induced by heavy-ions ( 12 C + 238 U at 90 MeV bombarding energy and 18 O + 208 Pb at 85 MeV) and studied with the Euroball array. Their high-spin level schemes have been extended to higher excitation energy from the triple γ-ray coincidence data. The γ − γ angular correlations have been analyzed in order to assign spin and parity values to many observed states. Moreover the half-lives of isomeric states have been measured from the delayed coincidences between the fission-fragment detector SAPhIR and Euroball, as well as from the timing information of the Ge detectors. The behaviors of the yrast structures identified in the present work are first discussed in comparison with the general features known in the mass region, particularly the breakings of neutron pairs occupying the νh 11/2 orbit identified in the neighboring Sn nuclei. The experimental level schemes are then compared to shell-model calculations performed in this work. The analysis of the wave functions shows the effects of the proton-pair breaking along the yrast lines of the heavy Te isotopes.

High-spin structure in the transitional nucleus Xe131 : Competitive neutron and proton alignment in the vicinity of the N=82 shell closure

“…Based on the experimental data, a J π = 27/2 6. Evolution of excited states in the negative-parity band along (a) the odd-mass N = 77 isotones from Z = 50 to Z = 64 [72][73][74][75][76][77] and along (b) the odd-mass Z = 54 isotopes from N = 69 to N = 77 [16,43,78]. Newly discovered states in 131 Xe are marked with thick lines.…”

“…Figure 6(a) shows the evolution of the negative-parity yrast band states along the N = 77 isotones from Sn to Gd [72][73][74][75][76][77]. The newly established states of 131 Xe are marked with thicker lines.…”

Millisecond 23/2+ isomers in the N=79 isotones Xe133Kaya1, Vogt2, Reiter3 et al. 2018Phys. Rev. C5070View full textAdd to dashboardCite

“…Based on the OSIRIS result and the reevaluated M2 character, a reduced transition strength of B(M2; 23/2 + 1 → 19/2 − 1 ) = 2.0(3) × 10 −6 W.u. [2] was deduced. Shell-model calculations predict a ν(h −2 11/2 d −1 3/2 ) configuration for the J π = (23/2 + ) state and a predominant (νh −1 11/2 )(πg 2 7/2 ) configuration for the J π = (19/2 − ) state.…”

“…The 361-keV transition was proposed to be of E3 character, connecting the isomer with a J π = (17/2 − ) state. Finally, in a later fusion-fission experiment by Astier et al [2] utilizing the EUROBALL array, the negative-parity band on top of the J π = (19/2 − ) state was extended to excitation energies of approximately 4.7 MeV and spin J π = (35/2 − ). The determined lower limit of the half-life of the J π = (23/2 + ) state (T 1/2 10 μs) is in agreement with the previous experiment.…”

“…Furthermore, several J π = 19/2 + , 23/2 + , and 27/2 − high-spin isomers above the J π = 11/2 − 1 states were reported in the literature. These isomeric states are explained as high-spin members of the ν(h −2 11/2 d −1 3/2 ) and ν(h −n 11/2 ), seniority v = 3 multiplets [1][2][3][4][5][6][7][8][9]. Information on excited states in 129 Sn and 131 Te were mainly obtained from β decay and actinide fission studies.…”