MSc Thesis Presentation: A study on low spin states in 154Gd using the (p, p′ γ) reaction

MSc Thesis Presentation

Candidate: Harris Bidaman

Abstract

The investigation of N = 90 nuclei have been the subject of many experimental studies.  These isotones, such as 154Gd and 152Sm, lie at the center of a region of rapid shape change between vibrational and rotational characteristics, and demonstrate striking similarities.  However, there are competing interpretations for the structure of these transitional nuclei.  In order to differentiate between them, a precise level scheme for each nucleus must be established.  The low-lying states of 154Gd were then investigated at the University of Jyväskylä accelerator laboratory in Finland, using the 154Gd(p, p′ γ) reaction.  A proton beam of 12 MeV was used to excite the 154Gd target, with the γ rays from the reaction detected with the JUROGAM II array, while the LISA charged-particle spectrometer was used for the detection of the inelastically scattered protons.  This experiment marked one of the first uses of the LISA spectrometer at Jyväskylä , and helped to distinguish between the (p, p′ ) reaction, and the much more copious (p, xn) channels.  By analysing the peaks obtained from the γ-γ, and γ-γ-proton coincidence matrices, a decay scheme has been built using the Radware software ESCL8R.  A total of 104 excited states are reported, with 36 being newly established in this work.  Experimental methods, new transitions, gamma branching ratios, and future steps will be discussed.

Examination Committee:

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