High-precision gamma-ray spectroscopy for enhancing the application of radioisotopes

Precise knowledge of the radiation emitted by unstable isotopes is needed in a number of applications including nuclear medicine. Many isotopes were last studied over 30 years ago with primitive detectors and no particular use in mind. Since then, gamma-ray spectroscopy has made tremendous advances, now using multiple high-purity germanium (HPGe) detectors employing Compton-suppression and high efficiency gamma-gamma coincidence spectroscopy. In the present work, we utilize these new techniques to improve the decay schemes of several isotopes with potential for PET imaging.

Sources were produced either at the University of Wisconsin or the Brookhaven Linac Isotope Producer and then shipped to Argonne National Laboratory for assay using the state-of-the-art gamma-ray spectrometer, Gammasphere, consisting of 100 Compton-suppressed HPGe detectors. In all studies, the high-sensitivity of Gammasphere allowed for significant revisions to the decay schemes, including the observation of many new levels and gamma-ray transitions and reduction in the uncertainties of gamma-ray intensities and deduced beta-feedings. An overview of results on ⁷⁶Br, ⁸⁶Y, and ¹⁸⁸Ir will be presented.