Citation
Dyer, Peggy Lynn (1973) The Reduced-Alpha-Width of the Lowest 1⁻ State of ¹⁶O. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/3PZ0-DY56. https://resolver.caltech.edu/CaltechTHESIS:10292015-105646231
Abstract
Cross sections for the reaction 12C(α,γ)16O have been measured for a range of center-of-mass alpha particle energies extending from 1.72 MeV to 2.94 MeV. Two 8"x5" NaI (Tℓ) crystals were used to detect gamma rays; time-of-flight technique was employed to suppress cosmic ray background and background due to neutrons arising mainly from the 13C(α,n)16O reaction. Angular distributions were measured at center-of-mass alpha energies of 2.18, 2.42, 2.56 and 2.83 MeV. Upper limits were placed on the amount of radiation cascading through the 6.92 or 7.12-MeV states in 16O. By means of theoretical fits to the measured electric dipole component of the total cross section, in which interference between the 1¯ states in 16O at 7.12 MeV and at 9.60 MeV is taken into account, it is possible to extract the dimensionless, reduced-alpha-width of the 7.12-MeV state in 16O. A three-level R-matrix parameterization of the data yields the width Θα,F2 = 0.14+0.10-0.08. A "hybrid" R-matrix-optical-model parameterization yields Θα,F2 = 0.11+0.11-0.07. This quantity is of crucial importance in determining the abundances of 12C and 16O at the end of helium burning in stars.
Item Type: | Thesis (Dissertation (Ph.D.)) | ||||||
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Subject Keywords: | (Physics) | ||||||
Degree Grantor: | California Institute of Technology | ||||||
Division: | Physics, Mathematics and Astronomy | ||||||
Major Option: | Physics | ||||||
Thesis Availability: | Public (worldwide access) | ||||||
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Defense Date: | 15 December 1972 | ||||||
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Record Number: | CaltechTHESIS:10292015-105646231 | ||||||
Persistent URL: | https://resolver.caltech.edu/CaltechTHESIS:10292015-105646231 | ||||||
DOI: | 10.7907/3PZ0-DY56 | ||||||
Default Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||
ID Code: | 9259 | ||||||
Collection: | CaltechTHESIS | ||||||
Deposited By: | Bianca Rios | ||||||
Deposited On: | 29 Oct 2015 23:18 | ||||||
Last Modified: | 16 Jul 2024 20:46 |
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