Proton Angular Distributions for (α, p) Reactions on C12, Al27, and P31

A. J. Lieber, F. H. Schmidt, and J. B. Gerhart
Phys. Rev. 126, 1496 – Published 15 May 1962
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Abstract

Angular distributions of protons corresponding to single and multiple levels of excitation have been measured for the reactions C12(α, p)N15, Al27(α, p)Si30, and P31(α, p)S34 using 42-Mev alpha particles. Distributions corresponding to the ground state and third-excited state of N15 and to the ground state and first-excited state of S34 show pronounced diffraction-like structure. Distributions from Si30 show a marked lack of structure. The data indicate that simple phasing relationships between distributions from levels of even and odd parity, predicted by models based on the plane-wave Born approximation, do not agree with experiment. The ground-state distribution from N15 is in agreement with the theories of Butler and Bhatia. However, the observed distribution from the third-excited state of N15 does not agree with the predictions of these theories. Total cross sections obtained for the ground state and third-excited state of N15 were large compared with those for low-level transitions in the reactions on phosphorus and aluminum. These in turn have much larger cross sections than those for Na23(α, p)Mg26, F19(α, p)Ne22, and Cl35(α, p)Ar38, which were too small to be investigated with our apparatus. There is some indication from this investigation that those distributions which show pronounced angular structure have cross sections that are more highly dependent on bombarding energy than those that lack structure.

  • Received 2 January 1962

DOI:https://doi.org/10.1103/PhysRev.126.1496

©1962 American Physical Society

Authors & Affiliations

A. J. Lieber*, F. H. Schmidt, and J. B. Gerhart

  • Department of Physics, University of Washington, Seattle, Washington

  • *Now at Palmer Physical Laboratory, Princeton University, Princeton, New Jersey.

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Issue

Vol. 126, Iss. 4 — May 1962

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