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Wednesday, January 25, 2012

Proton Capture and p-n Reactions

I was wondering what those 6-7 MEV protons observed by Piantelli would do, since they is much lower than the 14.2 MeV thought to be required for capture. Even if it just a side effect, it is worth knowing. I found this article which seems to provide some answers and may be worth buying:

Phys. Rev. 54, 1021–1025 (1938)

Proton Induced Radioactivities II. Nickel and Copper Targets

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Charles V. Strain
The University of Rochester, Rochester, New York
Received 14 October 1938; published in the issue dated December 1938
Nickel bombarded with 6.3-Mev protons shows activities of half-lives of 10.5±0.6 min., 3.4±0.3 hr., and 12.8±0.8 hr., corresponding to known periods of Cu62, Cu61 and Cu64, respectively. The reactions are principally of the p-n type but there is evidence that in the case of Cu62 proton capture occurs at energies below the p-n threshold. The maximum β-ray energies obtained by absorption method are 2.8, 1.2 and 0.68 Mev for Cu62, Cu61 and Cu64, respectively. Thick target excitation curves are given. Copper bombarded with 6.3-Mev protons shows two activities of half-lives 38.3±0.5 min. and 235±20 days due to Zn63 and Zn65, respectively. Both must be formed by p-n reactions. The Zn63 positrons have a maximum energy of 2.3±0.15 Mev. Thick target excitation curve shows a threshold proton energy of 4.1±0.1 Mev in good agreement with the energy relations. Average (thick target) cross section for the Cu63(p-n)Zn63 reaction is 0.28×10-25 cm2. For protons of energy 6.1 Mev it is 0.95×10-25 cm.
© 1938 The American Physical Society

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