Ty ¢ exposure rate at tine 6 I) = exposure rate at wit tine & os tim Fe exposure between tines t and to, where t > 10 seconds. It is expected that the decay of the residual refistion will vary with weapon design. Por example, the presence of Iy*-? would tend to decrease the absolute value of the decay exponent for a period of tine. 1.3.3 Absorption in Air. The absergtion of mecattered game refiation in air is exponential with distence. Freon s point source af monoenergetic radiation, the variation of intensity with distance is expressed as; eH? Ips ite A ee: were: Ip « intensity et distance D XI, « source intensity n « liner abeorption coefficient (this varies with gume energy, anf is generally lower fer higher energies). D = distance ST. LOUIS FRC The absorption coefficient // in Equation 1.2 is applicable fer sarrow-beam geometry, andi a correction shoulé be made for field cenditions woere the detector is approximately a 277 sensing element. ‘This is done by adding a buildup factor B to Equation 1.2, te aceount for the scattered radiation that will be detected. Buildup factors for different energies and Gistances have been calculated (Reference 10), ami some valuss are