for which values at only 1 MeV are available, the assatgtion must be made that the average value of the weapon's fast-neutron spectrum is 1 MeV. At stations where the full set of neutron activation detectors was not available, an average energy of 1 MeV for fast neutrons was assumed and only the neutron sensitivities at 1 MeV were used for ary gamma devectors Actually the neutron sensitivity values obtained for emulsions exposed. 548 and 649 and the thermoluminescent dosimeter were obtained by exposing them to a fission spectrum and reporting the values at an average energy of 1 MeV. 2.4 DETECTOR SHIELD CORRECTIONS (radiative capture) and fast neutrons (inelastic scattering) have bee uo pa nt2ractions (U) The corrections for the gamma dose produced by neutron in with-a number of popular shields have been reported in Reference 4 and are reproduced in Table 2.4. The contributions of thermal neutrons Induced activity in the shield is neglected (except taken into account. for aluminum shields), since calculations have shown thas its contriouThe inelastic scattering cross secfiors tion is less than two percent. below 0.63 MeV are negligible. (\) (erst As thé distance from ground zero increases, the gamma spectrum hardens (Reference 17) and the attenuation factor for shields would be expected to decrease. For surface and low-air bursts of less than 500 «t, the average gamma energy is considered to be 1 MeV at distances from ground zero to 1000 yards, 3 MeV from 1000 to 3000 yards, ard 5 MeV at greater than 3000 yards. The spectrum of gamma vadiation from weapons greater than 500 kt is expected to be consideratiy softer than that for low-yield weapons, since the major pertion oF tre dose is Melivered oy the hy ircdynarically enhanced fission-rrodu2ot radiation. For thes: weapo ic, the average ganma energy is considered to be 1 MeV up to 200) yards from ground zero and 3 MeV for grater distances. The snield avten- uation factors are reported in the initial gamma dose taoles 2.5 for each shot INTERACTION OF NEUTRONS WITH SOIL (U) The gamru contribution from the interaction of neutrons with the soil is reported but has not been used to correct the gamma data, inasmuch as the soil is part of the fixed environment. By means of the method outlined in Reference 5, phe gamma doses were calculated for various soils for fluxes of 1x10°? thermal neutrons per square centimeter 25