Date of Award

Spring 2012

Degree Type

Thesis

Degree Name

Master of Science (MSc)

Department

Physics and Astronomy

Supervisor

Alan A. Chen

Co-Supervisor

Donald Sprung

Language

English

Committee Member

Reza Nejat

Abstract

The astrophysical 30P(p,γ)31S reaction rate is a key quantity used in both classical nova and type I X-ray burst models that predict isotopic abundances produced during nucleosynthesis in the outburst. Currently, uncertainties in 31S structure parameters lead to a variation in the reaction rate by a factor of 20 at nova temperatures causing predicted isotopic abundance ratios in the Si-Ar mass region to vary by factors of up to 4. The 30P(p,γ)31S reaction rate can be determined indirectly by measuring transfer reactions populating excited states in 31S. Nuclear structure information for 31S resonant states above the proton threshold of 6131 keV and within the Gamow window that contribute most significantly to the reaction rate can be used to re-evaluate the rate for nova and type I X-ray burst temperatures and reduce current uncertainties. We have performed an experiment in order to study the level structure of 31S via the 32S(d,t)31S single-nucleon transfer reaction using the MP tandem accelerator and Q3D magnetic spectrograph at MLL in Munich, Germany. Excited states of 31S in the 6-7 MeV region were observed and spin-parity constraints have been suggested. In this work we describe the experimental setup, data analysis and results for both experiments and provide recommendations for further investigation of the 30P(p,γ)31S astrophysical reaction rate.

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