E.F. Zganjar

High-resolution γ-ray spectroscopy: a versatile tool for nuclear β-decay studies at TRIUMF-ISAC

High-resolution γ-ray spectroscopy is essential to fully exploit the unique, high-quality beams available at the next generation of radioactive ion beam facilities such as the TRIUMF isotope separator and accelerator (ISAC). The 8π spectrometer, which consists of 20 Compton-suppressed HPGe detectors, has recently been reconfigured for a vigorous research programme in weak interaction and nuclear structure physics. With the addition of a variety of ancillary detectors it has become the worlds most powerful device dedicated to β-decay studies. This paper provides a brief overview of the apparatus and highlights from recent experiments.

UNISOR on-line nuclear orientation facility (UNISOR/NOF)

The UNISOR on-line nuclear orientation facility (UNISOR/NOF) consists of a3He−4He dilution refrigerator on line to the isotope separator. Nuclei are implanted directly into a target foil which is soldered to the bottom accessed cold finger of the refrigerator. A 1.5 T superconducting magnet polarizes the ferromagnetic target foils and determines the axis of symmetry. Up to eight gamma detectors can be positioned around the refrigerator, each 9 cm from the target. A unique feature of this system is that the k=4 term in the directional distribution function can be directly and unambigously deduced so that a single solution for the mixing ratio can be found. The first on-line experiment at this facility reported here was a study of the decay of the191Hg and193Hg isotopes.

Shape coexistence and intruder states: theZ=82 region

The phenomena associated with shape coexistence and intruder states are illustrated with examples from the Pt, Au, Hg, Tλ, Pb and Bi isotopes which lie far from beta stability midway between closed neutron shells 82 and 126. The type of spectroscopic measurements which have already been developed to investigate these structures as well as those types of measurements needed to extend and quantify the analysis, such as on-line nuclear orientation, are discussed.

Structure of odd - odd : experiment and theory

The levels in have been studied employing the pn) reaction with the Bucharest tandem and the p) reaction at 95 MeV with the HHIRF tandem to enhance high spin states. New high spin states have been observed beginning at 1179.5 keV and they include a cascade up to 6092.2 keV, tentatively assigned . These results are compared with the theoretical calculations based on the VAMPIR models which also include neutron - proton mixing.

Detailed nuclear structure studies far from stability

State-of-the-art spectroscopy of nuclei far from stability has achieved an extraordinary level of sophistication and detail in the last ten years. In principle, if a state can be populated, it can be characterized by its energy, spin, parity, and major decay paths. Sometimes its lifetime can be measured. In practice, one is confronted with enormous complexity. To convert raw spectroscopic data into nuclear structure data involves a complex process of disentangling gamma rays and conversion electrons into decay schemes. Specifically, coincidence techniques, especially coincidence intensities, play a crucial role in this process. Recent examples and methods from work done at UNISOR are presented.