Statistical gamma-ray decay studies at iThemba LABS

¹ iThemba LABS, PO Box 722, Somerset West 7129, South Africa
² Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
³ University of California, Berkeley, California 94720-1730, USA
⁴ Lawrence Livermore National Laboratory, Livermore, California 94550-9234, USA
⁵ Stellenbosch University, Matieland 7602, South Africa
⁶ University of the Western Cape, Bellville 7535, South Africa
⁷ University of Oslo, 0316 Oslo, Norway
⁸ UM-DAE Centre for Excellence in Basic Sciences, Mumbai 400098, India
⁹ University of Zululand, KwaDlangezwa 3886, South Africa

^a e-mail: wiedeking@tlabs.ac.za

Published online: 13 September 2017

Abstract

A program to study the γ-ray decay from the region of high-level density has been established at iThemba LABS, where a high-resolution gamma-ray detector array is used in conjunction with silicon particle-telescopes. Results from two recent projects are presented: 1) The ⁷⁴Ge(α,α′γ) reaction was used to investigate the Pygmy Dipole Resonance. The results were compared to (γ,γ′) data and indicate that the dipole states split into mixed isospin and relatively pure isovector excitations. 2) Data from the ⁹⁵Mo(d,p) reaction were used to develop a novel method for the determination of spins for low-lying discrete levels utilizing statistical γ-ray decay in the vicinity of the neutron separation energy. These results provide insight into the competition of (γ,n) and (γ,γ′) reactions and highlights the need to correct for angular momentum barrier effects.