CHEMICAL DETERMINATION OF THE ISODOSE CURVE IN A Co$sup 60$ SOURCE "HOT SPOT Mk IV" OF 2000 CURIES DONATED TO THE PERUGIA ZOOPROPHYLACTIC INSTITUTE

A 2000 Co/sup 60/ Hot Spot Mk IV unit whose isodose curves were determined by the ferrous sulfate technique is described. The dose in the center of the chamber (8 cm x 14 cm) was about 500,000 rads/hr. Taking this figure to represert 100% of the dose, a 5% increase in the dose was found 1.5 cm from the center of the chamber laterally. The value increases from the center to the walls of the chamber. However, about 4 cm from the center of the chamber, proceeding toward its base, the value decreased 5%, and decreased progressively still more as measurements were made gradually nearer to the base. A table is presented from which the correction factors for Co/sup 60/ decay rate can be calculated. (auth)