Flux Attenuation in a Steel Side Shield at the AGS

The shielding properties of steel have been studied using an array of steel blocks near a target in the external beam of the AGS. Polyethylene foil detectors for 11C activation were used as beam monitors as well as to measure the flux distribution in the steel. Flux measurements were made on the face of the shield (10 in. from the beam axis) and at various locations in the array to a depth of 38 in. from the beam axis. In analyzing these results it is apparent that the usual models of exponential attenuation of flux with distance in the shield are unsuitable. A striking regularity is present; the ratio of radial distances from the target to isoflux lines is constant, independent of angle.