The experimental determination of C lambda using an absorbed dose calorimeter.

Abstract

The absorbed dose conversion factors, C lambda, were introduced, by Greene and Massey, as an interim measure until a primary standard for high energy photon dosimetry could be established. The theoretical basis of these factors has been discussed extensively and a more rigorous definition has emerged. Experiments have been carried out to determine the values of C lambda, for a Tufnol walled, Baldwin-Farmer ionisation chamber over a range of energies from cobalt-60 to 12 MV. The experimental results, based on measurements with a calorimeter, presented here support the more rigorous definition but it is shown that the values obtained depend, to a small extent, on the assumptions made about the detailed construction of the ionisation chamber for which C lambda is measured.