Degree

Doctor of Philosophy (PhD)

Department

Physics and Astronomy

Document Type

Dissertation

Abstract

The observation of the radioisotope 26Al is an indicator of ongoing nucleosynthesis in the Galaxy due to its short lifetime (t1/2 = 7.2 × 105 yr) on Galactic timescales. It is thought to be synthesized in several different environments in our Galaxy, one of which is in classical novae. Classical novae are stellar explosions that occur on the surface of a white dwarf in a binary system with a main sequence star. The isotopic production resulting from the nucleosynthesis that drives these explosions can be modeled with the input of nuclear reaction rates. In recent years, many of the reactions of importance to classical novae have been directly measured; one of the exceptions to this is the 26Alm(p, γ)27Si reaction, which is one of the primary destruction mechanisms for 26Al in novae. Because this reaction cannot be directly measured with radioactive ion beam intensities currently available, indirect experimental techniques are required. Here one such technique is discussed, including the installation and commissioning of the Silicon Array for Branching Ratio Experiments (SABRE), that is a vital part of the detector systems of the Super Enge Split-Pole Spectrograph (SE-SPS) at Florida State University. One of the first science runs conducted on this new experimental apparatus was the 27Al(3He,t)27Si(p)26Alg,m reaction, which was used to measure the proton branching ratios of states in 27Si of interest to the 26Alg,m(p,γ)27Si reactions. SABRE was able to detect proton decay branching ratios from resonance energies 200-400 keV lower than previously measured. This thesis will discuss this measurement and the commissioning of SABRE, which performs as expected. This will be followed by a discussion of the measurement of the branching ratios to the isomer state, the calculation of the 26Alm(p, γ)27Si reaction rate based on the results, and the effects this rate has on the synthesis of 26Al in classical novae.

Date

11-9-2020

Committee Chair

Deibel, Catherine

Included in

Nuclear Commons

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