Comparison of the Beta-Spectra of Boron 12 and Nitrogen 12

Author: Hilton, Henry Hoyt

Year: 1960

Degree: Dissertation (Ph.D.)

Advisors: Gell-Mann, Murray; Feynman, Richard Phillips

Committee Member: Unknown, Unknown

Option: Physics

DOI: 10.7907/W0PW-BR58

Abstract

This thesis, a "Comparison of the Beta-Spectra of Boron 12 and Nitrogen 12," is an attempt to test the nature of the vector interaction in beta-decay. The ratio of the matrix elements of the Boron 12 and Nitrogen 12 beta-decays is expected theoretically to have an energy dependence of the form (1 + 16/3 aE), where a is of the order of 2/M for the Conserved Vector Current Theory in which the virtual pions surrounding the nucleons carry the beta-decay charge, and is of the order of 2/5M for the Fermi Theory in which the virtual pions do not. Inserting for M the value of the nucleon mass, the expected energy dependences are 1.41%/Mev and 0.3%/Mev. Two separate determinations of this energy dependence were made by measuring the momentum spectra of the two beta-decays. The first gave 0.2 ± 1.2%/Mev, and the second gave 3.1 ± 1.2%/Mev. About half of these errors are systematic, and are the same for both experiments. Hence it seems wiser not to average the two experiments. The Conserved Vector Current Theory seems slightly favored by these two experiments.

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