0000000000698411
AUTHOR
M. Giles
Lifetime Measurements of Excited States in $^{172}$Pt and the Variation of Quadrupole Transition Strength with Angular Momentum
Lifetimes of the first excited 2 + and 4 + states in the extremely neutron-deficient nuclide 172 Pt have been measured for the first time using the recoil-distance Doppler shift and recoil-decay tagging techniques. An unusually low value of the ratio B ( E 2 : 4 + 1 → 2 + 1 ) / B ( E 2 : 2 + 1 → 0 + gs ) = 0.55 ( 19 ) was found, similar to a handful of other such anomalous cases observed in the entire Segré chart. The observation adds to a cluster of a few extremely neutron-deficient nuclides of the heavy transition metals with neutron numbers N ≈ 90 – 94 featuring the effect. No theoretical model calculations reported to date have been able to explain the anomalously low B ( E 2 : 4 + 1 → …
Decay spectroscopy of 171,172Os and 171,172,174Ir
We report on a study of the α-decay fine structure and the associated Eα−Eγ correlations in the decays of 171,172Os and 171,172,174Ir. In total, 13 new α-decay energy lines have been resolved, and three new γ-ray transitions have been observed following the new decay branches to 168Re and 167W. The weak α-decay branch from the bandhead of the νi13/2 band in 171Os observed in this work highlights an unusual competition between α, β, and electromagnetic decays from this isomeric state. The nucleus 171Os is therefore one of few nuclei observed to exhibit three different decay modes from the same excited state. The nuclei of interest were produced in 92Mo(83Kr,xpyn) fusion-evaporation reactions…
Evidence for octupole collectivity in 172Pt
Excited states in the extremely neutron-deficient nucleus 172Pt were populated via 96Ru(78Kr,2p) and 92Mo(83Kr,3n) reactions. The level scheme has been extended up to an excitation energy of ~ 5 MeV and tentative spin-parity assignments up to Iπ = 18+. Linear polarization and angular distribution measurements were used to determine the electromagnetic E1 character of the dipole transitions connecting the positive-parity ground-state band with an excited side-band, firmly establishing it as a negative-parity band. The lowest member of this negative-parity structure was firmly assigned spin-parity 3-. In addition, we observed an E3 transition from this 3- state to the ground state, providing…
Spin-dependent evolution of collectivity in 112Te
The evolution of collectivity with spin along the yrast line in the neutron-deficient nucleus 112Te has been studied by measuring the reduced transition probability of excited states in the yrast band. In particular, the lifetimes of the 4+ and 6+ excited states have been determined by using the recoil distance Doppler-shift method. The results are discussed using both large-scale shell-model and total Routhian surface calculations. peerReviewed