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Published November 1977 | public
Journal Article

Neutral Particle Background in Cosmic Ray Telescopes Composed of Silicon Solid State Detectors


The energy loss spectrum of secondary charged particles produced by the interaction of y-rays and energetic neutrons in silicon solid state detectors has been measured with a satellite-borne cosmic ray telescope. The products of these neutral-particle interactions are found to constitute a significant 'background' in typical spacecraft experiments designed to measure low energy cosmic rays. In the satellite measurements presented here two distinct neutral background effects are identified: secondary protons and alpha particles with energies of ≈2 to ≈100 MeV produced by neutron interactions, and secondary electrons with energies of ≈0.2 to ≈10 MeV produced by y-ray interactions. The implications of this neutral background for satellite measurements of low energy cosmic rays are discussed, and suggestions are given for applying these results to other detector systems in order to estimate background contamination and optimize detector system design. Our observations imply that the neutron induced background may be significant in many of the earlier quiet-time measurements of low energy cosmic ray protons and alpha particles in the so-called 'low energy turnup region'.

Additional Information

© 1977 by D. Reidel Publishing Company, Dordrecht-Holland. Received 16 August, 1976. Mr W. E. Althouse, Dr G. J. Hurford, and Dr J. E. Lupton made significant contributions to the design and development of the Electron/Isotope Spectrometer. In addition, Dr Hurford was responsible for some of the initial evaluations of neutral particle background in the EIS. Dr S. B. Vidor assisted in the neutron calibrations of the spare EIS instrument. This work was supported in part by the National Aeronautics and Space Administration under contract NAS5-11066 and grant NGR 05-002-160.

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