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An Experimental Study of a Stellar Neutron Source: ¹³C(α, n) ¹⁶O


Davids, Cary Nathan (1967) An Experimental Study of a Stellar Neutron Source: ¹³C(α, n) ¹⁶O. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/1S8V-K872.


Described in this thesis are measurements made of the thick-target neutron yield from the reaction 13C(α, n)16O. The yield was determined for laboratory bombarding energies between 0.475 and 0.700 MeV, using a stilbene crystal neutron detector and pulse-shape discrimination to eliminate gamma rays. Stellar temperatures between 2.5 and 4.5 x 108 oK are involved in this energy region. From the neutron yield was extracted the astrophysical cross-section factor S(E), which was found to fit a linear function: S(E) = [(5.48 ± 1.77) + (12.05 ± 3.91)E] x 105 MeV-barns, center-of-mass system. The stellar rate of the 13C(α, n)16O reaction if calculated, and discussed with reference to helium burning and neutron production in the core of a giant star.

Results are also presented of measurements carried out on the reaction 9Be(α, n)12C, taken with a thin Be target. The bombarding energy-range covered was from 0.340 to 0.680 MeV, with excitation curves for the ground- and first excited-state neutrons being reported. Some angular distributions were also measured. Resonances were found at bombarding energies of ELAB = 0.520 MeV (ECM = 0.360 MeV, Γ ~ 55 keV CM, ωγ = 3.79 eV CM) and ELAB = 0.600 MeV (ECM = 0.415 MeV, Γ ˂ 4 keV CM, ωγ = 0.88 eV CM). The astrophysical rate of the 9Be(α, n)12C reaction due to these resonances is calculated.

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.
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 March 1967
Funding AgencyGrant Number
Imperial Oil LimitedUNSPECIFIED
Office of Naval ResearchUNSPECIFIED
Record Number:CaltechTHESIS:11232015-105123847
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9286
Deposited On:23 Nov 2015 19:33
Last Modified:15 Mar 2024 21:39

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