Perturbation correction of a cylindrical thimble-type chamber in a graphite phantom for60Co gamma rays

Abstract

An experimental determination has been made of the perturbation correction to be applied to a graphite cylindrical (thimble-type) ionisation chamber used for the measurement of absorbed dose in graphite. The results show that the magnitude of this correction increases with depth and depends on the size of the cavity. The knowledge of this correction makes possible the use of such a chamber as a standard dose in graphite for ⁶⁰Co gamma rays.