Part I. A Study of the Na²³(ρ,α)Ne²⁰ Reaction for Proton Bombarding Energies from 100 to 450 KeV. Part II. A Measurement of the Half-Lives of N¹² and B¹² Half-Lives

Author: Fisher, Thornton Roberts

Year: 1963

Degree: Dissertation (Ph.D.)

Advisor: Whaling, Ward

Committee Member: Unknown, Unknown

Option: Physics

DOI: 10.7907/9ND5-CW79

Abstract

Part I. The ^(Na)23(p,α)Ne^(20) reaction has been studied for proton bombarding energies in the range 100 to 450 kev. Four narrow, isolated resonances have been observed in this region at proton bombarding energies of 286, 338, 374, and 445 kev. Excitation functions have been taken at each of these resonances, and the alpha yield, width, and resonance energy has been determined for each resonance. On the basis of angular distribution measurements, spin and parity assignments have been made for the resonances at 286, 338, and 374 kev. Upper limits have been established for the non-resonant cross section factor S and for the alpha yield from any unobserved resonance in the energy region covered. This experimental data has been used to calculate reaction rates for the Na^(23)(p,α)Ne^(20) reaction in stars whose temperature is in the range 5 to 10 x 10^8 °K. This is the range of temperatures in which the carbon burning process takes place.

Part II. The half-lives of N^(12) and B^(12) have been measured with greater experimental precision than had been achieved in previous measurements. Using the improved values for the half-lives, accurate ft values have been calculated for the decays of N^(12) and B^(12) to the C^(12) ground state. It is found that ft(N^(12)/ft(b^(12)) = 1.14 ± 0.025 implying that the ratio of the nuclear matrix elements |∫σ|^2(B^(12))/|∫σ|^2(N^(12)) is 1.14. The significance of the 14% difference in these matrix elements is discussed briefly.

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