Transport Calculations Pertinent to Satellite Detection of Delayed Gammas from an Atmospheric Nuclear Explosion.

A solution to the problem of measuring the transmission of delayed fission product gamma rays from atmospheric nuclear explosions from source to detector. Assuming detection by a VELA satellite or equivalent, calculations were made by means of a modification of the Rand x-ray and gamma-ray Monte Carlo program. For each of ten equal angular zones, ranging from directly below the detector to the horizon, gamma fluxes were computed at two satellite altitudes--110,000 and 35,000 km--for source heights of 55,000 ft, 65,000 ft, 75,000 ft, and 100,000 ft. Five thousand Monte Carlo histories were computed for each problem, requiring about 2.5 hours on the IBM 7044 for each. Numerical results are presented tabularly, in histograms, and with smoothed curves. Average standard deviation is 20 percent, and smoothing cuts it approximately 10 percent. A second run of 5000 histories was made for the 65,000-ft source, using a new set of initial random numbers, to check this deviation. Comparisons are made with results obtained using infinite medium buildup factors. 46 pp. Refs.