The β– decay of 116m1In (Iπ = 5+), studied using the 8π array at TRIUMF-ISAC, predominantly populated 4+ states in the semi-magic daughter 116Sn, with 50 protons and 66 neutrons. The resulting electromagnetic decays to the ground state were studied through conversion-electron spectroscopy and through angular correlations of coincident gamma rays. Conversion-electron spectroscopy allowed measuring K-shell internal conversion coefficients (αK), and angular correlations of coincident gamma rays allowed determinations of E2/M1 mixing ratios (δ). These values are reported and used to infer aspects of the underlying nuclear structure of 116Sn. In the course of the analysis, several αK values were measured, of which three were measured for the first time in decay spectroscopy. Additionally, ten mixing ratios were measured, eight of which were not previously reported.The 819 keV mixing ratio was re-measured with excellent agreement to literature results, whereas the 931 keV mixing ratio re-measurement indicates that the previously reported measurement requires a sign change. The 138 keV mixing ratio and αK were combined to measure an E0 component, a possible signature of shape coexistence.Measured transition mixing ratios between 4+ states reveal that these highly-mixed states have similar M1 transition strengths among them, but the E2 transition strengths to lower-lying 2+ states suggest underlying wavefunction differences that should be explored and interpreted with current and improved theoretical models of tin nuclei.
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Thesis advisor: Andreoiu, Corina
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