Performance of some handheld dosimeters used for gamma-ray ambient dose rate measurements

A study was carried out on the performance of some handheld dosimeters that are used for measuring ambient gamma dose rates. A CsI scintillation-based and two GM-based dosimeters were used to measure the absorbed dose rates in an indoor environment, inside a lead shield, on different floors of a building, in a desert environment and in a boat on the Arabian Gulf. The study showed that while some instruments provide measurements of ambient gamma dose rates, which include contributions from both terrestrial and cosmic radiation components, others show the terrestrial/indoor gamma dose rate only. Tests also showed that some dosimeters may fail to operate in the very low background radiation environments unless a radioactive source is used for the start-up.