No abstract available

[en] Short communication. 4 refs

[en] The (n,n'ß) reaction has been used to syudy systematically the low-lying level structures of stable heavy transitional nuclei. Detailed ß-ray excitation functions and angular distibutions have permitted the characeization of low-lyig nuclear states. Particular emphasis has been placed on understanding collective excitations of both positive and negative parity, and questions regarding nuclear shapes, deformation effects, and the applicbility of various nuclear models to these nuclei have been addressed. Completed studies of ₁₉₄Pt and ₁₉₈Pt reveal significant structural differences between these nuclei, while in complementary investigations the strucures of ₁₉₀Os, ₁₉₂Os, and ₂₀₀Hg have been examined. Comparisons of IBA and BET calculations with the properties of the positive-parity states are generally favorable, with only the low-lying O⁺ excitations providing significant inconsistences. Cross section symmematics for the (n,n'ß) reaction were explored and, where possible, ß-ray studies have been complemented by neutron detection time-of-flight measurements

[en] Systematic investigations of the nuclear level structures of stable heavy transitional nuclei are being performed by (n,n'γ) reaction spectroscopy. Detailed γ-ray excitation functions and angular distributions permit characterization of low-lying states, with particular emphasis on understanding collective excitations of both positive and negative parity. Questions regarding nuclear shapes, deformation effects, and the applicability of various nuclear models to these nuclei have been addressed. Completed studies of ¹⁹⁴Pt and ¹⁹⁸Pt reveal significant structural differences between these nuclei, and have led to studies of other transitional nuclei as the next step in a comprehensive examination of this mass region. Cross section systematics for the (n,n'γ) reaction are being developed and, where possible, γ-ray studies have been complemented by neutron detection time-of-flight measurements. 6 figures, 1 table

[en] An ¹⁶⁴Er target was bombarded by 620-MeV ¹³⁶Xe ions. The shape of the deexcitation gamma-ray line and the slowing-down time were used to determine lifetimes of high-spin states in ¹⁶⁴Er (8⁺, 3.69 ps; 10⁺, 1.46 ps; 12⁺, 0.8 ps). These values agree with rotational-model predictions within about 15%. 1 figure, 1 table

[en] The (n,nprimeγ) reaction has been used at the University of Kentucky accelerator facility to examine the detailed structure of a number of nuclei. The advantages of this method are reviewed, and recent developments are described. Examples of unique nuclear structure studies that have been carried out with this method are presented

[en] The level scheme of ¹⁶⁴Er was deduced from Coulomb excitation and ¹⁵⁰Nd(¹⁸O, 4nγ) reactions. A conventional backbending plot is included. 2 figures

[en] Gamma-gamma coincidences following the inelastic scattering of accelerator-produced monoenergetic neutrons have been experimentally observed. A coincidence system consisting of a neutron collimator and three HPGe γ-ray detectors, is shown to provide important information on the isotopic identification and placement of γ rays. The development and use of the system is described, and initial results are presented

[en] The inelastic neutron scattering (INS) reaction has been shown to populate both collective and non-collective nuclear states in a statistical manner. Moreover, with this reaction, it is often possible to probe excited states that cannot be examined with other reactions. Recent advances in Doppler-shift attenuation method (DSAM) techniques following INS have permitted the author to determine lifetimes in the femtosecond regime in heavy nuclei, and these measured lifetimes have been used to identify possible low-spin collective excitations. In two mass regions, he obtained evidence for fast E1 transitions; these transitions are offered as evidence for octupole-octupole and quadrupole-octupole excitations. However, he found the occurrence of fast E1 transitions to be a more common phenomenon than expected and was forced to question whether such transitions can unambiguously be taken as evidence of collective character. In the rare earth region, he has been able to observe γ-ray de-excitation from M1 scissors mode states and to measure the lifetimes of these states

[en] Using the (n,n'γ) reaction, five heavy transitional nuclei (sup(190,192)Os, sup(191,192)Ir, sup(194)Pt) belonging to two supersymmetric multiplets of the U(6/4) supersymmetry model were studied. Excitation functions permitted the placement of many new levels, while excitation function shapes, angular distribution measurements, and γ-ray decay systematics aided in spin-parity assignments. The abundance of spectroscopic data obtained for these nuclei permits meaningful evaluation of this model. (author)