Statistical gamma-ray decay studies at iThemba LABS

M Wiedeking,K Sowazi,B V Kheswa ,S N T Majola ,L A Bernstein ,K L Malatji ,T Nogwanya ,M Guttormsen ,A Görgen ,D Negi ,A C Larsen ,B L Goldblum ,S Siem ,C.p Brits ,D L Bleuel ,B R Zikhali

doi:10.1051/epjconf/201714605006

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 74 Ge(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 95 Mo(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.

Highlights

An incredible wealth of information can be obtained from experimental investigations of the low-energy tail of the Giant Electric Dipole Resonance
The Photon Strength Function (PSF), which represents the ability of nuclear matter to absorb and emit photons, is one of the quantities that can be successfully used to extract information in the region of the quasi-continuum
2.1. 74Ge For 74Ge three relevant data sets are available from the reactions 74Ge(3He,3He ) [7] and 74Ge(4He,4He ) [8], and 74Ge(γ, γ ) [9], which were obtained through an international effort of several institutes

Summary

Introduction

An incredible wealth of information can be obtained from experimental investigations of the low-energy tail of the Giant Electric Dipole Resonance. The Photon Strength Function (PSF), which represents the ability of nuclear matter to absorb and emit photons, is one of the quantities that can be successfully used to extract information in the region of the quasi-continuum. Most of the knowledge of the underlying nuclear structure is obtained by combining results from several experimental approaches and techniques. Significant experimental effort has been invested to study the γ -ray decay from the region of high-level density below the particle separation energies at many laboratories worldwide. Coordinated measurements have taken place, selecting specific nuclei and extracting the PSF through several experimental methods or beam/target combinations

Results

Discussion

Conclusion