Nuclear Structure aspects of gamma decay from giant resonances

P Ádám,A Bracco,T.S Biró,S Ceruti,L Pellegri,S Varró,G.G Barnaföldi,P Lévai

doi:10.1051/epjconf/20147806002

Abstract

The gamma decay of the giant dipole resonance (including its tail region) is an important tool to probe the properties of these states, and thus to test the predictions of mean field theories. This paper focuses on two main aspects concerning the electric dipole excitation in nuclei. These are the study of the isospin character of the low energy tail of the Giant Dipole Resonance (GDR), the so-called Pygmy resonance, and the isospin mixing of nuclear systems at finite temperature. In the first case, the Pygmy resonance has been populated in the inelastic scattering reaction 17O+124Sn at 20 MeV/u. Its gamma decay has been measured using the AGATA Demonstrator and an array of 8 large volume LaBr3:Ce scintillators. In the second case, the gamma decay of the GDR in thermalized nuclear systems, formed in fusion evaporation reactions, has been used to investigate the isospin mixing in 80Zr. For this work the reactions 40Ca+40Ca at 3.4 MeV/u and 37Cl +44Ca at 2.6 MeV/u were used.

Highlights

The gamma decay of the high-lying electric dipole states up to the region of the giant dipole resonance is an important tool to address relevant physics questions of nuclear structure related to nuclear collectivity and isospin effects.This paper reports on preliminary results of two experiments performed at the LNL/INFN laboratory using the AGATA demonstrator array
The first is the isospin character of the low-lying part of the dipole response, commonly denoted as the Pygmy resonance, due to the much smaller size of its strength in comparison with the Giant Dipole Resonance (GDR)
The second topic concerns the investigation of isospin mixing at finite temperature by measuring the gamma decay of the GDR excitation

Summary

Introduction

The gamma decay of the high-lying electric dipole states up to the region of the giant dipole resonance is an important tool to address relevant physics questions of nuclear structure related to nuclear collectivity and isospin effects. The second topic concerns the investigation of isospin mixing at finite temperature by measuring the gamma decay of the GDR excitation.

Results

Conclusion