Decay spectroscopy with Solenogam at the ANU Heavy Ion Accelerator Facility

Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601, Australia

^a e-mail: matthew.gerathy@anu.edu.au

Published online: 5 September 2016

Abstract

Solenogam is a recoil spectrometer designed and constructed for use at the Australian National University (ANU) Heavy-Ion Accelerator Facility (HIAF). The design enables the study of nuclear excitations populated by the decay of long-lived states such as isomers and radioactive ground states. Solenogam is comprised of high-sensitivity γ-ray and electron detector arrays coupled to a new 8-T solenoid. While the installation of the 8-T solenoid proceeds, off-line measurements have been made to characterise Solenogam’s performance. Gamma-electron coincidences in the electron capture decay of ¹⁸²Re into ¹⁸²W were used to investigate conversion coeffcients and γ-e^– angular correlations. The measured conversion coeffcients show good agreement with theoretical calculations and have been used to extract E0/E2 mixing ratios for a number of J → J transitions. The angular correlations measured by the array are in qualitative agreement with theoretical calculations. However, the magnitudes of the correlations are attenuated by approximately 40% for reasons unknown at present. These results are the first full use of the Solenogam system for γ-e^– coincidence measurements and have proven that the system is capable of highly-sensitive internal conversion analysis of complex decays.