Late-Time Sources for Close-In EMP (Electromagnetic Pulses)
Final rept. 3 May 1971-2 Aug 1972
SCIENCE APPLICATIONS INC LA JOLLA CA
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The report describes calculations of ionization rates and electric currents in air and ground resulting from neutron sources. In particular, the report describes the numerical methods, nuclear data, and computer programs employed and presents results for a typical thermonuclear neutron spectrum. A discussion of fitting of earlier electromagnetic pulse EMP source calculations is also presented. The latest ENDFB neutron transport and gamma ray production data for air and ground are used and sensitivity of EMP calculations to cross section changes have been estimated. A new source energy band version of the Monte Carlo code 05RNIES has been developed which makes it possible to compute EMP sources by folding in various desired neutron spectra. New analytical approaches have also been introduced to accurately treat neutron capture events in air to times as late as one second. Analytical gamma-ray transport calculations away from the air-ground interface are used. Various neutron and gamma-ray contributions to ionization rates and electric currents have been tabulated as functions of fast and thermal reactions to assist in fitting of these quantities.
- Nuclear Physics and Elementary Particle Physics