Development of a detector for the measurement of ambient dose equivalent, H∗(10) at low and medium photon energies.

Ionization chambers are used as secondary standards for the dosimetric measurement of photon radiation as the current generated in it are directly proportional to the conventional true value of the monitoring quantity (i.e. air kerma, dose or ambient dose equivalent). The wall thickness of ionization chamber plays an important role in the dosimetric measurement of photon energies below 200 keV. A 10 mm thick, poly methyl methacrylate walled, cylindrical ionization chamber having 225 cm3 volume was developed to study ambient dose equivalent rate based response at photon energies below 200 keV. The developed ionization chamber shows a near flat energy response for the monitoring of ambient dose equivalent in the energy range 30-200 keV. It also fulfills the ISO 4037-4 requirements concerning the quality of a secondary standard dosimeter in the energy range ∼15-200 keV.