Measurement of Grenz rays

Abstract

The paper by Rollo, Katchis and Dauer (1968), "A Calorimetric Method for the Measurement of grenz rays ", leaves unanswered several questions, so that it is not obvious that the method described does in fact give results which are either correct for the radiation used, or consistent with theory.The calorimeter is designed so that the grenz rays traverse a path 10.2 cm long from the target to the absorber (during calorimetry) or to the ionization chamber (when measuring the exposure). In the first instance, there is a vacuum between the Melinex entrance window and the absorber, while in the second there is air, the window being removed. The distance from window to absorber is not stated but appears to be about 3.5 cm, and this amount of air will transmit less than 90% of 10 kv radiation 10 cm F.S.D., while the Melinex window transmits roughly 94%. A correction was applied for the latter but not apparently for the former. This factor will also produce quality differences between the respective beams.