Investigations of Spectroscopic Factors and Sum Rules from the Single Neutron Transfer Reaction111Cd($\overrightarrow {\rm{d}} $,p)112Cd

D.S Jamieson,R Hertenberger,A.A Phillips,T Faestermann,K.G Leach,P.E Garrett,P Finlay,K.L Green,C.S Sumithrarachchi,S Triambak,G.A Demand,R Krücken,H.-F Wirth,G.C Ball

doi:10.1051/epjconf/20146602056

Abstract

Cadmium isotopes have been presented for decades as excellent examples of vibrational nuclei, with low-lying levels interpreted as multi-phonon quadrupole, oc- tupole, and mixed-symmetry states. A large amount of spectroscopic data has been ob- tained through various experimental studies of cadmium isotopes. In the present work, the 111 Cd(~ 112 Cd reaction was used to investigate the single-particle structure of the 112 Cd nucleus. A 22 MeV beam of polarized deuterons was obtained at the Maier-Leibnitz lab- oratory in Garching, Germany. The reaction ejectiles were momentum analyzed using a Q3D spectrograph, and 130 levels have been identified up to 4.2 MeV of excitation energy. Using DWBA analysis with optical model calculations, spin-parity assignments have been made for observed levels, and spectroscopic factors have been extracted from the experimental angular distributions of differential cross section and analyzing power. In this high energy resolution investigation, many additional levels have been observed compared with the previous (d,p) study using 8 MeV deuterons (1). There were a total of 44 new levels observed, and the parity assignments of 34 levels were improved.

Highlights

The energy spacings and spin-parity values of low-lying levels in the cadmium isotopes have a compelling similarity to the spectrum of a spherical harmonic vibrational system
The 111Cd(d,p)112Cd single neutron transfer reaction probes the single-particle components of states in 112Cd, which provides a good test of the assignments made for phonon states within 112Cd
The deuteron elastic scattering data were used to fix which global optical parameters to use in the DWBA analysis of the transfer data

Summary

Introduction

The energy spacings and spin-parity values of low-lying levels in the cadmium isotopes have a compelling similarity to the spectrum of a spherical harmonic vibrational system. Vibrational nuclear structure involves highly collective modes of excitation, where a 1-phonon state is a superposition over many two quasi-particle states near the Fermi surface. Quadrupole and octupole single-phonon and multi-phonon states have been proposed in the cadmium isotopes, as well as coupled quadrupoleoctupole states. A highly collective state, such a multi-phonon excitation, should be weakly populated in a single nucleon transfer. Bojowald et al (1988) Daehnick, Childs, and Vrcelj (1980) An and Cai (2006) Han, Shi, and Shen (2006)

Spectroscopic factors and sum rules

Summary and outlook