D.B. Fossan

Transverse BGO Compton suppression shield

The performance of a Compton suppressed Ge spectrometer, that utilizes a transverse BGO suppression shield, is presented. A comparison of the experimental measurements and Monte Carlo calculations is made.

A versatile electronic pulse-shape discriminator

Abstract A pulse-shape discrimination circuit designed for use with multidetector arrays has been tested. Each module, containing two channels, occupies a single slot in a standard nuclear instrumentation module (NIM) crate and can be used without alteration, tests have shown, with either NE213 liquid scintillator detectors for neutron-gamma ray discrimination or with NaI(Tl) detectors for charged particle identification. Variations of the circuit which minimize either the power consumption or the complexity are presented. Outputs are provided for either a charge-to-digital converter or a time-to-digital converter.

Neutron orbitals above the N = 74 shell gap at large deformation: spectroscopy in the superdeformed minimum of 133Ce

Abstract High-spin states in 133 Ce were populated via the 116 Cd( 22 Ne,5n) reaction at 120 MeV. Analysis of these data has revealed three new superdeformed bands in 133 Ce, two of which have transitions which are identical to those observed in the yrast bands of 132 Ce and 136 Nd. These bands have been interpreted as signature partners of the [530] 1 2 − orbital coupled to the 132 Ce yrast superdeformed core. The third band is believed to be built upon a π5 4 ν6 3 configuration at high rotational frequency and to show the effects resulting from an alignment of a pair of f 7 2 neutrons at ℏgω ⋍ 0.7 MeV. It is tentatively suggested that the sharp rise in the dynamic moment of inertia of this band at low rotational frequency may result from an admixture of the π5 4 ν6 1 configuration.

The g-factor of the 252+ isomeric state in 207At; evidence for neutron excitation☆

The g-factor of the 2117 keV 252+ isomer in 207At has been measured to be g = 0.30 ± 0.01, which strongly supports a (vi132−1)(vf52−1)9− ⊗ (φh923)92− structure. In addition, a calculation of the multiplet energies for this structure agrees with the observation that the lowest-lying member has a spin Jmax−1 = 252.

High-spin states in Zr 92

High-spin states have been investigated with the /sup 88/Sr(/sup 7/Li, p2n)/sup 92/Zr reaction by ..gamma..-..gamma.. coincidence, ..gamma..-ray angular distribution, and pulsed beam-..gamma.. timing measurements with Ge(Li) detectors. Decay schemes, level energies, and spin-parity information were obtained for /sup 92/Zr from the data. The high-spin states involving the (..pi..1g/sub 9///sub 2/)/sup 2/(..nu..2d/sub 5///sub 2/)/sup 2/ configuration were identified, with the (12/sup +/) member being at 4947 keV. Tentative identification of the members of the (..pi..1g/sub 9///sub 2/..pi..2p/sub 1///sub 2/)(..nu..2d/sub 5///sub 2/)/sup 2/ configuration has also been made. The observed experimental levels in /sup 92/Zr are compared with recent theoretical calculations. (AIP)

Neutron i 1 3 / 2 intruder band in Sm 139

The high-spin structure of [sup 139]Sm has been investigated with the [sup 110]Pd([sup 34]S,5[ital n]) reaction at a beam energy of 159 MeV at the Stony Brook Tandem/Superconducting LINAC facility. The TESSA3 spectrometer array was used to collect [gamma]-[gamma] coincidence data from which an extended decoupled band structure has been found. It is proposed that this band is based on the [ital i][sub 13/2] ([Omega]=1/2) neutron intruder orbital. The decay pattern, enhanced dynamic moments of inertia, and aligned spins are consistent with the [nu][ital i][sub 13/2] bands in neighboring odd-neutron nuclides. Total Routhian surface and cranked shell model calculations reproduce qualitative features of these nuclides, further supporting the proposed interpretation.

Intermediate and weak coupling in Ra 219

The level scheme of

Properties of high-spin states in Nb 91 and Zr 91 via Li 6 -induced reactions

^{219}\mathrm{Ra}

High-spin states in odd-mass /sup 113en-dash119/Sb:. delta. J = 1 bands on 9/2/sup +/ proton-hole states

established via a study of the

Deformed 9/2/sup +/ proton-hole states in odd-A I nuclei

^{208}\mathrm{Pb}