Response of TSEE dosemeters of foil-covered BeO thin films to beta radiation

The TSEE of foil-covered BeO thin film detectors is well suited for the measurement of Hs(d) because of the extremely small escape depth of exoelectrons. Even for the low energy beta radiation from 147Pm there is no need for correction factors. The sensitivity is almost the same as to gamma radiation from 60Co with a lower detection limit of some 10 μSv. Detectors have been covered with tissue-equivalent foils of various thicknesses and exposed to beta radiation sources on a flat Perspex phantom at different angles of radiation incidence. Their response corresponded to the conversion coefficients determined by extrapolation chamber measurements for angles of radiation incidence ≤ 60o. At large angles the response to beta radiation from 90Sr/90Y is affected by the side wall of standard detectors. (author)