Edward Herbert Seabury

K-isomers in Hf nuclei at and beyond the neutron-rich edge of β-stability

New high-K isomers are populated in {sup 180,181,182}Hf nuclei via inelastic excitation and transfer reactions, using pulsed {sup 238}U beams on Hf targets. The new data explore K-hindrances for different multipolarities and the role of residual spin-spin interactions for multi-quasiparticle (qp) configurations at the neutron-rich edge of the {beta}-stability line. The mapping of 4-qp K-isomers in the A {approx} 180 region is extended into neutron-rich territory.

Beta particle spectrometer for measuring aggregate beta spectra following fission

Abstract The beta spectrometer consists of a gated plastic scintillator suitable for measuring aggregate beta energy spectra following fission. This general utility spectrometer is very insensitive to the gamma rays accompanying the fission products, has good linearity, and adequate energy resolution for these continuous beta energy distributions. Response functions are measured below 1 MeV and trial sets of response functions are tested with known beta spectra extending to 5 MeV.

Unsafe coulomb excitation of 240–244Pu

The high spin states of 240Pu and 244Pu have been investigated with GAMMASPHERE at ATLAS, using Coulomb excitation with a 208Pb beam at energies above the Coulomb barrier. Data on a transfer channel leading to 242Pu were obtained as well. In the case of 244Pu, the yrast band was extended to 34ℏ, revealing the completed πi13/2 alignment, a “first” for actinide nuclei. The yrast sequence of 242Pu was also extended to higher spin and a similar backbend was delineated. In contrast, while the ground state band of 240Pu was measured up to the highest rotational frequencies ever reported in the actinide region (∼300 keV), no sign of particle alignment was observed. In this case, several observables such as the large B(E1)/B(E2) branching ratios in the negative parity band, and the vanishing energy staggering between the negative and positive parity bands suggest that the strength of octupole correlations increases with rotational frequency. These stronger correlations may well be responsible for delaying or supp...