Cross sections for production of the 15.10-MeV and other astrophysically significant gamma-ray lines through excitation and spallation of C12 and O16 with protons

F. L. Lang, C. W. Werntz, C. J. Crannell, J. I. Trombka, and C. C. Chang
Phys. Rev. C 35, 1214 – Published 1 April 1987
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Abstract

The ratio of the flux of 15.10-MeV gamma rays to the flux of 4.438-MeV gamma rays resulting from excitation of the corresponding states in C12 is a sensitive measure of the spectrum of the exciting particles produced in solar flares and other cosmic sources. These gamma rays are produced predominantly by interactions with C12 and O16, both of which are relatively abundant in the solar photosphere. Gamma-ray production cross sections for proton interactions have been reported previously for all important channels except for the production of 15.10-MeV gamma rays from O16. The first reported measurement of the 15.10-MeV gamma-ray production cross section from p+16O is presented here. A cyclotron was employed to produce 40-, 65-, and 85-MeV protons which interacted with CH2 and BeO targets. The resultant gamma-ray spectra were measured with a high-purity germanium semiconductor detector at 70, 90, 110, 125, and 140 deg relative to the direction of the incident beam for each proton energy. Other gamma-ray lines resulting from direct excitation and spallation reactions with C12 and O16 were observed as well, and their gamma-ray production cross sections, several of which have not been reported previously, are presented. The results are compared with previously reported measurements, as available.

  • Received 18 August 1986

DOI:https://doi.org/10.1103/PhysRevC.35.1214

©1987 American Physical Society

Authors & Affiliations

F. L. Lang and C. W. Werntz

  • Code 682, Solar Physics Branch, Laboratory for Astronomy and Solar Physics, NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 and Department of Physics, The Catholic University of America, Washington, D.C. 20064

C. J. Crannell and J. I. Trombka

  • Code 682, Solar Physics Branch, Laboratory for Astronomy and Solar Physics, NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771

C. C. Chang

  • Department of Physics and Astronomy, University of Maryland, College Park, Maryland 20742

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Vol. 35, Iss. 4 — April 1987

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