Electron dosimetry with thermally stimulated exoelectron emission (TSEE)

The dependence of exoelectron emission from BeO and Al2O3 on primary electron energy has been measured over the 200 keV to 1.2 MeV range. Two types of measurements are made, firstly with the isotopes 90Sr + 90Y, 147Pm, 204Tl, and secondly for BeO with monoenergetic electrons from an accelerator. The TSEE response of covered BeO-dosemeters (cover of 7 mg cm-2 polyethylene) is independent from electron energies in the 200 to 700 keV range for constant equivalent doses (ICRP 21). The experimental results for uncovered TSEE-dosemeters and electron fluences are in agreement with calculations performed using a Monte Carlo program developed by Seltzer and Berger. The TSEE responses for electrons and photons in equivalent dose units are very similar. A lower detection limit of 20 mu Gy (absorbed dose in air) is found for this dosemeter.