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In an experiment at the HRIBF, Oak Ridge National Laboratory, USA, we have investigated excited states in 86Se populated in the beta-decay of 86As. Several new transitions were identified. Preliminary results are presented. [ABSTRACT FROM AUTHOR]

Decay-spectroscopy study of the67mFe isomer has been performed at GANIL. This isomer is found to have an energy of 387 keV and a half-life of 75(21) μs. An intermediate excited state is introduced at 367 keV. The results are interpreted in terms of various nuclear models, and a deformed shape is inferred for67Fe. [ABSTRACT FROM AUTHOR]

The very neutron-deficient isotope 50Ni was produced in fragmentation reactions between a 650 A MeV 58Ni beam and a 9Be target. For the first time the decay of this nucleus was investigated, leading to the determination of the half-life as 12+3 -2 ms and the branching ratio for β-delayed proton emission of (70 ± 20)%. [ABSTRACT FROM AUTHOR]

An experiment was performed at the National Superconducting Cyclotron Laboratory at Michigan State University to investigate β decay of very neutron-rich cobalt isotopes. Beta-delayed neutron emission from 71-74Co has been observed for the first time. Preliminary results are reported. [ABSTRACT FROM AUTHOR]

The β -decay properties of very neutron rich nuclei 86Ge and 86As were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Spectroscopic information on new excited states in 86As and in 86Se was obtained and is interpreted within an advanced shell model approach. These calculations, previously explaining well the structure of 84Ge and 85Ge, are not able to reproduce all the experimentally determined features of the measured level schemes of 86As and 86Se. The Gamow-Teller decay of 86Ge and 86As is also investigated in a shell-model framework. The fission yield for 86Ge is discussed. [ABSTRACT FROM AUTHOR]

The β-decay properties of neutron-rich 87As produced in the proton-induced fission of 238U were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The low-energy excited states in N = 53 87Se and N = 52 86Se were identified through β-γ and β-delayed neutron-γ decay of 87As, respectively. The experimental systematics of low-energy levels of N = 53 isotones, Z = 34 87Se, and Z = 32 85Ge, and along with an analysis of shell-model calculations, allow us to discuss the main features of excited states expected for the next N = 53 isotone, 83Zn. [ABSTRACT FROM AUTHOR]

The β-decay properties of neutron-rich 85Ga produced in proton-induced fission of 238U were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Data consisted of β - γ and β - γ - γ coincidences were collected at the Low-energy Radioactive Ion Beam Spectroscopy Station after high-resolution on-line mass separation. For the first time, the excited states in the N = 53 isotone 85Ge were established from β-delayed γ decay of 85Ga. The level scheme of the N = 52 isotone 84Ge was improved and includes now 0+, 2+, (2)+, 4+, and (0)+ states populated in the β-delayed-neutron-γ decay of 85Ga. Advanced shell-model calculations were used to analyze experimental data on 85Ge and 84Ge. [ABSTRACT FROM AUTHOR]

The g factors of the first-excited states of stable 124Sn and radioactive 126,128Sn were measured by the recoil-in-vacuum method with comparatively high precision. The experiments were performed at the Holifield Radioactive Ion Beam Facility by Coulomb exciting ~3 MeV/u beams in inverse kinematics on carbon and titanium targets. The results for 124Sn and 126Sn are in excellent agreement with recent shell-model calculations. For 128Sn the experiment suggests an increase in the magnitude of g(2+1), as predicted by some models. The present results provide a sensitive probe of the valence orbitais that contribute to the 2+1 wave functions as the double-shell closure at 132Sn is approached. [ABSTRACT FROM AUTHOR]

The β-decay properties of several neutron-rich germanium and arsenic isotopes were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The measurements of almost-pure radioactive sources were enabled by the combination of ion-source chemistry and two-stage mass separation. The half-life of 86Ge (226±21 ms) was determined for the first time, while those of 84,85Ge and 84-87As were remeasured. The results are compared to theoretical predictions of the gross theory of β decay, the finite-range droplet model, and the new calculations using the energy density functional DF3a with continuum quasiparticle random-phase approximation (CQRPA). We confirm the robustness and good predictive power of the latter model for nuclei near closed shells. These DF3a+CQRPA calculations were used recently to analyze r-process isobaric abundances. [ABSTRACT FROM AUTHOR]

The β-decay properties of neutron-rich Cu isotopes produced in proton-induced fission of 238U were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The data were collected using high-resolution online mass separation, reacceleration, and digital β-γ spectroscopy methods. An improved decay scheme of N = 49 78Cu and the first observation of N = 50 79Cu β-delayed neutron decay followed by a gamma transition are reported. Spin and parity (5-) are deduced for 78gsCu. The β-delayed neutron branching ratios (Pβn) for the 77Cu and 79Cu precursors are analyzed with the help of nuclear structure models. [ABSTRACT FROM AUTHOR]

An experiment to search for the a decay of 112Cs has been performed at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. The a decay of 112Cs was not observed, thus setting the upper limit of the &agr; branching ratio at 0.26%. The half-life of 112Cs was measured as 506±55μs. In the same measurement the decay properties of its proton decay daughter 111Xe were also reinvestigated. The newly measured a branching ratio for 111Xe is 10.4 ± 1.9 %. The experimental proton separation energies Sp for odd-Z nuclei above l0OSn were compared to shell model calculations. The calculated proton separation energies for 103Sb and 102Sb point to half-lives of the order of 10 ps and 1 ns, respectively. [ABSTRACT FROM AUTHOR]

The low-energy level structures of 6425Mn39 and 6625Mn41 were investigated through both the decay of Mn metastable states and the population of levels following the &bgr; decay of MCr and 64Cr and 66 Cr. The deduced level schemes and tentatively assigned spins and parities suggest the coexistence of spherical and deformed configurations above and below N = 40 for the odd-odd Mn isotopes. The low-energy deformed configurations are attributed to the coupling between a proton in a K = 1/2- level with neutrons in either the K = 1/2- or the K = 3/2+ levels originating from the π3/2, νp1/2, and νg9/2 single-particle states, respectively. [ABSTRACT FROM AUTHOR]