[en] This is a final report on a nuclear structure research program of long duration at Purdue University. A listing of research publications during the last five years is presented

[en] Excitations of nuclei close to magic ¹³²Sn have been investigated by analysis of fission product γ-ray data measured at Eurogam II using a ²⁴⁸Cm source. Results for the N=82 isotopes up to ¹³⁶Xe, for the one proton-one neutron nucleus ¹³⁴Sb, and for the N=84 isotones ¹³⁴Sn. ¹³⁵Sb, and ¹³⁶Te are summarized. The interpretation of the observed level spectra is mainly based on shell model calculations using empirical proton-proton interactions from ¹³⁴Te, neutron-neutron interactions from is ¹³⁴Sn, and proton-neutron interactions estimated (with scaling as A^-1/3) from the well-known ²¹⁰Bi spectrum

[en] Prompt and delayed γ-ray coincidence measurements have located (νh_11/2)ⁿ yrast isomers in ¹²⁵Sn and ¹²⁶Sn among the products of heavy ion reactions on ¹²⁴Sn targets. The decay properties of the two isomers are reported, and the results are related to those obtained for other tin isotopes in earlier works

[en] Prompt and delayed γ -ray cascades in doubly magic < hspace SPACE=''-0.167''>¹³²Sn and its neighbor < hspace SPACE=''-0.167''>¹³¹Sn have been studied at Gammasphere using a < hspace SPACE=''-0.167''>²⁴⁸Cm fission source. Isotopic assignments of unknown γ rays were based on coincidences with known transitions in A=112--116 Pd fission partners. The yrast level spectra of both tin nuclei are interpreted using empirical nucleon-nucleon interactions from the < hspace SPACE=''-0.167''>¹³²Sn and < hspace SPACE=''-0.167''>²⁰⁸Pb regions. Results include identification of the (νf_7/2 h^-1_11/2)9⁺ aligned state in < hspace SPACE=''-0.167''>¹³²Sn and of extensive (νf_7/2 h^-2_11/2) , (νf_7/2 d^-1_3/2 h^-1_11/2) and (νh^-1_11/2 x 3^-) multiplets in < hspace SPACE=''-0.167''>¹³¹Sn . The previously reported β^- decay of an unusual < hspace SPACE=''-0.167''>¹³¹In high-spin isomer to levels in < hspace SPACE=''-0.167''>¹³¹Sn is also elucidated

[en] Gamma-ray cascades in the two- and three-valence-particle nuclei ¹³⁴Sb and ¹³⁵Te have been studied with Gammasphere using a ²⁴⁸Cm spontaneous fission source. Isotopic assignments were based in part on coincidences with γ rays from complementary Rh and Ru fission partners. The ¹³⁴Sb and ¹³⁵Te level schemes have been considerably extended, with placement of many new high-energy γ rays; delayed γ-ray coincidences observed across a 0.51-μs yrast isomer in ¹³⁵Te were especially fruitful. The yrast level spectra of both nuclei are interpreted using empirical nucleon-nucleon interactions and compared with the known yrast excitations of their counterparts ²¹⁰Bi and ²¹¹Po

[en] Prompt γ-ray cascades in neutron-rich nuclei around doubly magic ¹³²Sn have been studied at Eurogam II using a ²⁴⁸Cm fission source. Here we report results for the four-valence-proton N=82 nucleus ¹³⁶Xe and for its N=83 neighbor ¹³⁷Xe. For both nuclei, the yrast level spectra have been considerably extended, and empirical nucleon-nucleon interactions have been used to assign probable shell model configurations for most of the observed levels

[en] Spectra of the E2 quasicontinuum γ rays feeding different spin regions of the ¹⁵⁴Dy yrast line have been extracted. These are compared with corresponding theoretical spectra obtained by numerical simulations based on temperature-dependent Hartree-Fock theory, with thermal shape fluctuations. In this manner, different regions of the spin-energy plane can be examined. The results support the predictions of a smeared-out phase transition at high spin above the yrast line. (c) 2000 The American Physical Society

[en] Excited states in the nucleus ¹³³Sb, populated in spontaneous fission of ²⁴⁸Cm, were studied with EUROGAM2. Medium-spin structure, described as the ν(f_7/2h_11/2^-1) multiplet of the ¹³²Sn core coupled to the odd proton in the g_7/2 orbital, has been identified in this nucleus. Levels corresponding to the octupole excitations of the ¹³²Sn core were also identified. Some uncertainties concerning isomeric decays in ¹³³Sb, observed in previous works, have been resolved. (c) 2000 The American Physical Society