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The structure of 72Se was investigated following the ϵ/β+ decay of 72Br produced in the 58Ni(16O, pn) reaction at 50 MeV. Using a beam chopping system, off-beam γ-ray decay data was collected with an array of clover Ge detectors. γ-γ coincidence measurements provided a significant modification of the prior level scheme, and γ-γ angular correlation measurements allowed spin determinations and multipole mixing ratio extraction. The new information on the non-yrast states was combined with previous in-beam data to investigate the issue of shape coexistence by comparing to various configuration mixing approaches. Clear evidence for shape coexistence is found, with a ground state of modest, or slightly oblate, deformation and a well-deformed prolate shape that would lie at an unperturbed excitation of 875 keV. The shape mixing is near complete at low spin. [ABSTRACT FROM AUTHOR]

A study of excited states in 63Ni up to an excitation energy of 28 MeV and a probable spin of 57/2 was carried out with the 26Mg(48Ca,2α3nγ )63Ni reaction at beam energies between 275 and 320 MeV. Three collective bands, built upon states of single-particle character, were identified. For two of the three bands, the transition quadrupole moments were extracted, herewith quantifying the deformation at high spin. The results have been compared with shell-model and cranked Nilsson-Strutinsky calculations. Despite the Z = 28 shell closure and the approach to the purported N = 40 subshell, the 63Ni isotope is able to sustain collective excitations at moderate and high spin. [ABSTRACT FROM AUTHOR]

The decay of K isomers in Cm (Z = 96) isotopes has been studied using inelastic and transfer reactions. The half-life of a previously identified 2-quasiparticle (qp) Kπ=8- isomer in 246Cm has been measured. A new 2-qp isomer is observed in 248Cm, its half-life measured and its decay scheme established. The reduced K hindrances extracted for the decay transitions from the isomers in 246,248Cm indicate K to be a robust quantum number and validate axial symmetry in these nuclei. The excitation energies of the 2-qp isomers in 246Cm (N = 150) and 248Cm (N = 152) support the persistence of a deformed subshell gap at N = 152 in the Z≈100 region down to Z = 96 nuclei. [ABSTRACT FROM AUTHOR]

A six-quasiparticle isomer with T1/2 = 57(2) ns has been established in the doubly-odd isotope 200Tl and its level scheme is significantly extended. Half-lives of previously reported isomers in 200Tl and 201,202Pb have been determined and revised values are reported in a few cases, with T1/2 = 397(17) ns and 7.0(5) ns for the Iπ = 5+ and 7- states in 200Tl, 52(2) ns for the 41/2+ level in 201Pb, and 93(4) ns for the 16+ state in 202Pb. Configurations for the isomers have been assigned and these predominantly involve intrinsic excitations of neutrons from the i13/2 subshell. The inferred transition rates for the decay of these isomers compare well with single-particle estimates attesting to their intrinsic character. [ABSTRACT FROM AUTHOR]

The structure of decoupled positive-parity and semidecoupled negative-parity bands up to high spin in 197,199Hg has been studied using multinucleon transfer reactions with the Gammasphere array. A positive-parity band in 199Hg with the (νi13/2)³ decoupled configuration that deexcites to levels in the negative-parity sequences is newly established. The semidecoupled sequences in both isotopes are extended to higher spin. Rotation-aligned angular momenta and crossing frequencies determined from experiment are in fair agreement with those from cranking calculations. A transition from oblate collective rotation at low spin to triaxial noncollective shapes at high spin is indicated. [ABSTRACT FROM AUTHOR]

The structure of the odd-A isotopes 193,195,197Pt, which lie along the line of stability, has been studied up to high spin through multinucleon transfer reactions. Positive- and negative-parity sequences in 193,195Pt have been considerably extended and multiple band crossings established. An isomer with T1/2=5.0(5) ns and Iπ=25/2- is present in 195Pt. The isotopes 193,195Pt are characterized by moderate oblate deformation, and angular momentum generation at high spin in the yrast, positive-parity sequences is attributed to the rotation alignment of i13/2 neutrons and h11/2 protons. A detailed understanding of the observed features is presented using calculations based on tilted axis cranking covariant density functional theory as well as others with the ultimate CRANKER code. [ABSTRACT FROM AUTHOR]