Coulomb Excitation of Proton-rich N = 80 Isotones at HIE-ISOLDE

R D Kern ,J Snäll ,L Kaya ,V Karayonchev ,V Werner ,T Kröll ,G Rainovski ,J M Keatings ,M Djongolov ,D Rosiak ,O Möller ,E Giannopoulos ,D Kocheva ,A Welker ,J Jolie ,J G Cubiss ,C Fransen ,P Reiter ,J Wiederhold ,N Warr ,S Thiel ,P.-A Söderström ,K Gladnishki ,H Hess ,L P Gaffney ,A Vogt ,M Scheck ,R Stegmann ,J Pakarinen ,A Boukhari ,N Pietralla ,G O’neill ,J Cederkäll ,R Zidarova ,A Blazhev ,M Stoyanova ,P Spagnoletti ,H De Witte

doi:10.1088/1742-6596/1555/1/012027

Abstract

A projectile Coulomb-excitation experiment was performed at the radioactive ion beam facility HIE-ISOLDE at CERN. The radioactive 140Nd and 142Sm ions were post accelerated to the energy of 4.62 MeV/A and impinged on a 1.45 mg/cm2-thin 208Pb target. The γ rays depopulating the Coulomb-excited states were recorded by the HPGe-array MINIBALL. The scattered charged particles were detected by a double-sided silicon strip detector in forward direction. Experimental γ-ray intensities were used for the determination of electromagnetic transition matrix elements. Preliminary results for the reduced transition strength of the of 140Nd and a first estimation for 142Sm have been deduced using the Coulomb-excitation calculation software GOSIA. The states of 140Nd and 142Sm show indications of being the main fragment of the proton-neutron mixed-symmetry state.

Highlights

The origin of quadrupole collectivity in most heavy open-shell nuclei is the attractive quadrupolequadrupole interaction between valence protons and neutrons
A theoretical approach to the modeling of quadrupole-collective heavy nuclei, which provides a bridge to the calculation of nuclear properties from fundamental nucleon-nucleon interactions to the collective model, is the interacting boson model (IBM) [2]
The IBM-2 [3], which distinguishes between proton and neutron bosons, predicts another class of states, the mixedsymmetry states (MSSs)

Summary

Introduction

The origin of quadrupole collectivity in most heavy open-shell nuclei is the attractive quadrupolequadrupole interaction between valence protons and neutrons. This interaction results in a coherent mixing of collective quadrupole excitations of the proton and neutron subspaces and leads to low-energy nuclear states, in which protons and neutrons collectively move in phase. The nucleus is considered as a homogeneous object with a certain shape, which can vibrate or rotate [1] This approach neglects the many-body character of the nuclear system. The IBM-2 [3], which distinguishes between proton and neutron bosons, predicts another class of states, the mixedsymmetry states (MSSs). The proton and neutron motions of these states are partly out of phase

Discussion

Conclusion