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Measurement of 23Na(α,p)26Mg at Energies Relevant to 26Al Production in Massive Stars and Nucleosynthesis in Type 1a Supernovae

Tomlinson, Jessica (2015) Measurement of 23Na(α,p)26Mg at Energies Relevant to 26Al Production in Massive Stars and Nucleosynthesis in Type 1a Supernovae. PhD thesis, University of York.

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Abstract

26Al is an important radionuclide in astrophysics. Its decay to 26Mg results in the emission of a 1.8 MeV gamma-ray which is detected and mapped across the galaxy, providing evidence of ongoing nucleosynthesis in the universe. Its origin is still not understood, however observations suggest massive stars as a possible main production site. A post processing network calculation study modelled nucleosynthesis in the C/Ne convective-shell before the core collapse of a massive star and found that the 23Na(α,p)26Mg reaction is important for the synthesis of 26Al in this environment. Due to large uncertainties in previous experimental measurements of this reaction, theoretically calculated Hauser-Feshbach cross sections were used to calculate the 23Na(α,p)26Mg reaction rate for the post processing calculations. This theoretical rate has large uncertainties as the statistical model used to calculate the cross sections is not thought to be applicable for the level density of the compound nucleus 27Al. The 23Na(α,p)26Mg reaction is also found to play an important role in the nucleosynthesis of several nuclei in type Ia supernovae explosions by several sensitivity studies. Again these studies used the reaction rate from Hauser-Feshbach statistical model cross-section calculations. A measurement has been made of the 23Na(α,p)26Mg reaction cross section in inverse kinematics using the TUDA scattering chamber at TRIUMF laboratory in Canada. The cross sections were calculated in the energy range Ec.m. = 1.28 - 3.15 MeV and found to be in reasonable agreement with the Hauser Feshbach model calculations. A new reaction rate has been calculated providing tight constraints on the uncertainty in the production of 26Al in the C/Ne convective shell of massive stars due to the 23Na(α,p)26Mg reaction.

Item Type: Thesis (PhD)
Academic Units: The University of York > Physics (York)
Identification Number/EthosID: uk.bl.ethos.684626
Depositing User: Miss Jessica Tomlinson
Date Deposited: 27 Apr 2016 09:42
Last Modified: 08 Sep 2016 13:34
URI: http://etheses.whiterose.ac.uk/id/eprint/12576

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