a Seventeen Chemical Corps smoke generators (modified M3's produced smoke screens of 300-yd maximum width 100-ft maximum thickness, and of concentrations ranging from 0.6 to 7.5 g/sa m. The results show that an oil fog consisting of particles approximately 0.1 »p in diameter and at a concentration of 1 g/sq m over flat terrain attenuates by approximately 75% the solar radiation incident at an inclination of 309, CRLR - 320 - PRELIMINARY CALCULATIONS ON THE CONCENTRATION OF FOG-OIL SMOKE REQUIRED FOR THERMAL ATTENUATION. Elmer H. Engquist, 5 April 1954. SECRET-RESTRICTED DATA The object of the work described in this report was to make an atomic weapons in order to determine the quantity of fog-oil smoke needed, uniformly dispersed over an area, to reduce the ground range of thermal effects to that of moderate blast effect. ae ee analysis of the range of blast, nuclear, and thermal effects of air-burst Data obtained from TM 23-200, Capabilities of Atomic Weapons, were used for analysis of the ground range of blast, nuclear, and thermal effects, The criterion established for calculating and predicting the required quantity of smoke was the amount necessary to reduce the thermal Fiux to 3 cal/sq cm at the range where blast overpressures were 8 1b/sq in, To make the preliminary estimates, data on attenuation of thermal radiation as a function of path length and concentration were necessary. Data ob- tained in laboratory experiments using a carbon are as a thermal source and data obtained in a field test using the sun as a thermal source, were emplcye= in this study. CRLR - 326 - EXPERIMENTAL-THEORETICAL ATTENUATION OF 1.2 MEV GAMMA RADIATION BY SIMPLE STRUCTURES. Ralph E. Rexroad, David L. Dunbar, and John C. ~Peale,———..15 September 1953. CONFIDENTIAL - The object of the work described in this report involved etermination of the following: 1. The minimum area to produce the effect of an infinite field, or total plane, of contamination. 2. The dose rate at various heights above a relatively flat, uniformly contaminated plane as a function of contamination density. REST A Gua” WNAG e