MSc Thesis Presentation: Investigation of excited 0+ states populated in the 162Er(p,t) reaction

MSc Thesis Presentation

Candidate: Christina Burbadge

Abstract

Interpreting the nature of excited states in well-deformed nuclei has been an ongoing challenge in our understanding of nuclear structure. Some of the approaches that have been implemented to interpret the occurrence of low-lying excited 0+ states include vibrational excitations in β-phonons and γ-phonons, as well as pairing excitations. One of the difficulties in resolving the nature of these states is that there is a paucity of data, particularly for excited 0+ states, in the rare earth region.

Two-neutron transfer reactions are ideal for probing 0+ → 0+ transitions in deformed nuclei. One of the intriguing features of the rare-earth region are the strongly-populated 0+ states that emerge in both (p,t) and (t,p) two-neutron transfer reactions that have been interpreted as signatures of shape coexistence and pairing isomerism. In the present work, excited 0+ states have been studied via the 162Er(p,t)160Er reaction at the Maier-Leibnitz Laboratory in Garching, Germany using 22 MeV and 24 MeV proton beams and the reaction products were momentum-analyzed with the Q3D magnetic spectrograph. The variance in the cross section of these low-lying excited 0+ states, with the 02+ state population around 18% of the ground state strength, suggests a special character for this state which is inconsistent with a β-vibration interpretation. The similarity of the population of the 02+state in 160Er with low-lying 0+ states in N=90 isotones suggests that the nature of these excitations are quite similar, with the possibility that the 02+ state is an example of shape coexistence. Results of the relative population of the excited 0+ states in 160Er will be presented, and placed into context with similar experiments in the N = 90 region.

Examination Committee

• Dr. Robert Wickham, Chair
• Dr. Paul Garrett, Advisor
• Dr. Carl Svensson