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The absolute cross section for the reaction D(p,a)3 He from 400 Kev to 100 Kev Helmer, Richard Lloyd


The absolute cross section of the reaction D(p,ɣ)³He has been measured in the energy range from 400 Kev to 1100 Kev in the laboratory system. A target of deuterated polyethylene was used to measure the relative yield of the reaction over this range, and the results were normalized to an absolute measurement made with a deuterium gas target. The reaction is of interest because it enables some information to be obtained about the forces binding three nucleons together. It also has some significance in a number of astrophysical processes. In order to determine the cross section, the intrinsic efficiency of a 5 inch by 4 inch sodium iodide crystal scintillation counter was measured by simultaneous alpha particle and gamma ray counting on the 340 Kev resonance of the reaction ¹⁹F(p,[symbol omitted]ɣ)¹⁶0. The intrinsic efficiency of the detector was found to be .679 ± .03 for the 6.14 Mev gamma rays from this reaction, with the particular geometry used. The absolute cross section for the reaction D(p ɣ)³He was found by the gas target measurement to be 2.33 ± .07 microbarns for an incident proton energy of 643 kev.

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