Green's-function approach to the atmospheric albedo neutron-transport problem. Master's thesis

Technical Report · Fri Mar 01 00:00:00 EST 1991

OSTI ID:6137645

Culp, D R

This study investigated the reflection of neutron radiation off of the earth's upper atmosphere, with the goal of generating a quick-running computer algorithm to estimate the albedo free field flux at any point above the atmosphere. This thesis involved analytic development in the construction of the algorithm and employed Monte Carlo simulation for generating the energy and angle distributions of the reflected radiation. The Green's function approach to modeling the neutron transport process involved approximating each energy bin of the source spectrum as a Dirac pulse in energy and summing the contribution from each source bin. The computer program integrates over the surface of the atmosphere and uses the Monte Carlo data to calculate the albedo flux at any specified time and location. Run time was maximum of six minutes for a flux calculation, but a gain on the order of one thousand should be achieved on mainframe computer systems. The albedo flux from an instantaneous point source raises quickly to a maximum and then falls off over time. Albedo fluxes as much as 10(-16) (neutrons/square cm sec/source neutron) were calculated. The accuracy of the algorithm is greatly affected by the fineness of the energy bins involved.

• Research Organization: Air Force Inst. of Tech., Wright-Patterson AFB, OH (United States). School of Engineering
• OSTI ID: 6137645
• Report Number(s): AD-A-238884/1/XAB
• Resource Relation: Other Information: Master's thesis
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
EARTH ATMOSPHERE
ALBEDO
NEUTRONS
REFLECTION
ACCURACY
ALGORITHMS
CALCULATION METHODS
EXOSPHERE
GAIN
GREEN FUNCTION
MONTE CARLO METHOD
NEUTRON TRANSPORT THEORY
SIMULATION
SPECTRA
AMPLIFICATION
BARYONS
ELEMENTARY PARTICLES
FERMIONS
FUNCTIONS
HADRONS
MATHEMATICAL LOGIC
NUCLEONS
TRANSPORT THEORY
661320* - Auroral
Ionospheric
& Magnetospheric Phenomena- (1992-)