Measurement and R-Matrix Analysis of the 15N(p,g)16O Reaction Cross Section

Doctoral Dissertation

Abstract

Along with the p-p chains, the CNO cycle is the main source of energy production inside of stars with masses larger than the sun. The 15N + p reaction is the first branch point of this cycle, where the (p,&alpha) reaction returns material to the CN cycle and the (p,&gamma) reaction leads to the NO cycle, and thus plays a role in determining the final energy production of the process and influences the abundances of oxygen isotopes.

This project involves obtaining new measurements for the 15N(p,&gamma)16O reaction. Dominated by two broad resonances at Ep = 338 and 1028 keV, measurements of this reaction were performed in the proton energy range from 1800 keV down to 130 keV. Particular attention was paid to the area between the two dominant resonances, along with the low energy region, as these are the most important regions in determining the S(0) extrapolations. To obtain this measurement, article accelerators at both the University of Notre Dame’s Nuclear Science Laboratory (NSL) and the Underground Laboratory for Nuclear Astrophysics (LUNA) in Gran Sasso, Italy were used. In both locations, high purity germanium detectors were used to detect &gamma-rays from the reaction of around 13 MeV.

It was not possible to measure down to energies corresponding to relevant stellar environment temperatures, and so theoretical fits and extrapolations to the data must be made. To this end, the multi-level, multi-channel R-matrix code AZURE was used. The resulting S factor calculations were used to calculate new reaction rates for different temperature values, and gives up to a factor of 2 difference from currently used compilations~cite{Angulo1999}.

Attributes

Attribute NameValues
URN
  • etd-06162010-150917

Author Paul James LeBlanc IV
Advisor Gary Bernstein
Contributor Michael C.F. Wiescher, Committee Member
Contributor Ani Aprahamian, Committee Member
Contributor Umesh Garg, Committee Member
Contributor H. Gordon Berry, Committee Member
Contributor Gary Bernstein, Committee Chair
Degree Level Doctoral Dissertation
Degree Discipline Physics
Degree Name PhD
Defense Date
  • 2010-04-16

Submission Date 2010-06-16
Country
  • United States of America

Subject
  • nuclear astrophysics

  • nitrogen 15

  • CNO cycle

  • hydroden burning

  • underground

Publisher
  • University of Notre Dame

Language
  • English

Record Visibility and Access Public
Content License
  • All rights reserved

Departments and Units

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