
Accession Number : AD0838387
Title : PHOTON TRANSPORT FROM A POINT SOURCE IN THE ATMOSPHERE.
Descriptive Note : Master's thesis,
Corporate Author : AIR FORCE INST OF TECH WRIGHTPATTERSON AFB OH SCHOOL OF ENGINEERING
Personal Author(s) : Bigelow, Winfield S., Jr
Report Date : JUN 1968
Pagination or Media Count : 205
Abstract : A moments calculation was performed for a point, isotropic source of photons in a homogeneous atmosphere. This calculation produces photon density as a function of position and energy. The calculation is carried out for steadystate sources, which means that the results are also applicable to timeintegrated photon densities produced by pulsed sources. The uncollided and oncescattered contributions are obtained analytically; the multiplyscattered component is obtained from spatial moments of the spherical harmonic moments of the photon distribution by an expansion in biorthogonal polynomials. In this technique, monoenergetic sources are treated directly, while continuous source spectra are treated by superposition of monoenergetic sources of appropriate strengths. Results are presented for a series of calculations for monoenergetic sources in the 20 KeV to 8 MeV range, and for two continuous source spectra. (These calculations did not account for pair production.) The angleintegrated photon densities are wellconverged out to at least 15 meanfreepaths. Angledependent densities, however, are poorly represented beyond one meanfreepath. (Author)
Descriptors : (*NUCLEAR EXPLOSIONS, ATMOSPHERES), (*PHOTONS, TRANSPORT PROPERTIES), ATMOSPHERE MODELS, FLOW CHARTING, COMPUTER PROGRAMS, INCOHERENT SCATTERING, PHOTOELECTRIC EFFECT, GAMMA RAYS, X RAYS, SPECIAL FUNCTIONS(MATHEMATICAL), MONTE CARLO METHOD, NUMERICAL ANALYSIS, POLYNOMIALS, SERIES(MATHEMATICS), THESES.
Subject Categories : Nuclear Physics & Elementary Particle Physics
Distribution Statement : APPROVED FOR PUBLIC RELEASE