Nuclear Structure aspects of gamma decay from giant resonances

Dipartimento di Fisica dell’Universitá di Milano e INFN, I-20133 Milano, Italy

Published online: 25 September 2014

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.