Nucleon-nucleon correlations probed at far sub-Coulomb energies

S Szilner,F Scarlassara,A M Stefanini,N Soić,T Mijatović,G Montagnoli,L Corradi,J J Valiente-Dobón,D Mengoni,D Montanari,D Jelavić Malenica,A Goasduff,E Fioretto,G Pollarolo

doi:10.1051/epjconf/201716300058

S Szilner, F Scarlassara + Show 12 more

Open Access

https://doi.org/10.1051/epjconf/201716300058

Copy DOI

Abstract

Excitation functions of one- and two-neutron transfer channels have been measured for the closed shell 40 Ca+96 Zr and superfluid 60 Ni+116 Sn systems from the Coulomb barrier energy to energies far below. By using the unique PRISMA performance in terms of resolution and efficiency, measurements at very low bombarding energies have been performed. In the case of the 60 Ni+116 Sn system, a complementary particle-γ coincident measurements provide the ground and excited state populations.The experimental transfer probabilities have been compared with semiclasical microscopic calculations that incorporate nucleon-nucleon correlations, together with known structure information of entrance and exit channels nuclei and reaction dynamics. These calculations well reproduce, in the whole energy range, one- and two-neutron transfer channels in shape and magnitude.

Highlights

Pairing interaction induces particle-particle correlations that are essential in defining the properties of finite quantum many body systems in their ground and neighbouring states. These structure properties may influence in a significant way the evolution of the collision of two nuclei, i.e. the effects of pair correlations affect a variety of nuclear processes
The pair correlations have been studied in measurements of two-particle transfer reactions by extraction of enhancement coefficients, defined as the ratio of the actual cross section to the prediction of models using uncorrelated states
The experimental evidence obtained by these factors is often obscured by the fact that almost all existing studies involve inclusive cross sections at energies higher than the Coulomb barrier, where the reaction mechanism is complicated by the interplay between nuclear and Coulomb trajectories

Summary

Introduction

Pairing interaction induces particle-particle correlations that are essential in defining the properties of finite quantum many body systems in their ground and neighbouring states These structure properties may influence in a significant way the evolution of the collision of two nuclei, i.e. the effects of pair correlations affect a variety of nuclear processes. The pair correlations have been studied in measurements of two-particle transfer reactions by extraction of enhancement coefficients, defined as the ratio of the actual cross section to the prediction of models using uncorrelated states. Such enhancement factors, in principle, should provide a direct measurement of the correlation of the populated states. By taking advantage of the high energy resolution of γ detectors, such measurements allowed to define how the transfer strength is distributed over the single states

Sub-barrier measurements

The particle-γ coincident measurement

Nucleon-nucleon correlations

Findings

Summary and outlook