The Physical Measurements of Electron Beams from 6 to 18 Mev: Absorbed Dose and Energy Calibration

Abstract

An aluminium calorimeter has been used to measure the G-values for the ferrous sulphate dosemeter for incident electron energies of 1325, 159 and 18 Mev. The ferrous sulphate dosemeter was then used to determine the correction factor to be applied to an ion chamber reading taken in a Lucite phantom to obtain absorbed dose in water. The factor was found to vary by 2% from 6 to 18 Mev, which can be correlated to the change in the average relative stopping power of the electrons in the phantom and the gas, taking the polarization effect into account. The absorbed dose calibration using the above method is accurate to within 2%. A quick and relatively accurate method has been described for determining the energy of the electron beam. Agreement within 3% has been found between this method and the method utilizing the measured electron range.