Equation 1.6 indicates that a ray originating in the center of the sphere would traverse only '4 of the mass in the shell model that it would in the homogeneous model. The result would be an enhancement of radiation. Once the shell of material in the shock front passes the detector, an even greater enhancement results. As previously stated, the N'4 (n, y) componentof initial radiation is essentially emit- ted within 0.2 second. Since it takes at least one second for the shock front to reach a detector at a distance of 7,000 feet (even for devices in the order of 6 Mt), the N' (n, y) component is not significantly enhances. The fission-product gamnm.as continue to con- tribute during the first 30 seconds; therefore, this radiation is strongly enhanced by the shock wave. 17