Inelastic Neutron Scattering on160Gd

S R Lesher,Z Tully,S W Yates,E E Peters,F M Prados-Estévez,B P Crider,R Ikeyama,I Marsh,A Aprahamian,J R Vanhoy,M K Smith,C Casarella

doi:10.1051/epjconf/20146602063

Abstract

The nature of low-lying excitations, Kπ=0+ bands in deformed nuclei remain enigmatic in the field, especially in relationship to quadrupole vibrations. One method of characterizing these states beyond excitation energies is through measurements of absolute transition probabilities. In the rare earth region of deformation, there are five stable Gd isotopes, 154Gd, 156Gd, and 158Gd have been studied to obtain B(E2) values, a fourth, 160Gd is the focus of this work. We have examined 160Gd with the (n, n′γ) reaction and neutron energies up to 3.0 MeV to confirm known 0+ states.

Highlights

Since the work of Bohr and Mottelson [1], the lowest excited 0+ state and the second excited 2+ state in deformed nuclei were expected to result from quadrupole vibrations built on the deformed ground state with a projection of K = 0 and K = 2 on the symmetry axis
The γ vibration is a shape change against the axis of symmetry, and is identified by collective transitions from the Kπ = 2+ band decaying to the ground state
The argument is two-fold - Does the band first excited K= 0+ band decay to the γ band or to the ground state, and is this decay collective, i.e., does it involve several nucleons or just a pair of nucleons? If the K= 0+ band decays to the γ band, it can be viewed as an excitation built on the K= 2+ gamma band

Summary

Introduction

Since the work of Bohr and Mottelson [1], the lowest excited 0+ state and the second excited 2+ state in deformed nuclei were expected to result from quadrupole vibrations built on the deformed ground state with a projection of K = 0 and K = 2 on the symmetry axis. The γ vibration is a shape change against the axis of symmetry, and is identified by collective transitions from the Kπ = 2+ band decaying to the ground state. The β vibration, is a shape change along the axis of symmetry and should be a collective Kπ = 0+ excitations.

Results

Conclusion