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The ¹⁶O(α,γ)²⁰Ne and ²⁸Si(α,γ)³²S Reactions at Low Energy


Toevs, James Waldo (1970) The ¹⁶O(α,γ)²⁰Ne and ²⁸Si(α,γ)³²S Reactions at Low Energy. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/MHA9-5P97.


The ²⁸Si(α,γ)³²S and ¹⁶O(α,γ)²⁰Ne reactions have been investigated to provide data for the calculation of the stellar rates of these reactions. The gamma rays were counted with a NaI(Tl) detection system having a high detection efficiency which is approximately independent of the gamma-ray cascade structure of a nuclear level; the detection efficiency was determined experimentally. The reaction ²⁸Si(α,γ)³²S was studied for He⁺ bombarding energies from 1.4 to 2.7 MeV, and in this region, five new resonances were found, and their strengths, (2J+1) Γ_α Γ_γ/ Γ were measured. An upper limit for the cross section has also been established for bombarding energies below 1.7 MeV. The ¹⁶O(α,γ)²⁰Ne reaction was investigated in the energy region from 0.85 to 1.8 MeV; strengths for the previously known resonances were measured, and an upper limit for the cross section was determined for energies below 1 MeV. Stellar interaction rates and photodisintegration rates have been calculated from the measured resonance strengths, and semi-empirical fits to these rates have been given to facilitate astrophysical calculations.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Physics)
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Fowler, William A. (advisor)
  • Barnes, Charles A. (advisor)
Thesis Committee:
  • Unknown, Unknown
Defense Date:30 December 1969
Record Number:CaltechTHESIS:05172010-110558216
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:5813
Deposited By: Tony Diaz
Deposited On:17 May 2010 19:00
Last Modified:22 May 2024 18:02

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