Adsorbed gases, atmospheric, and temperature effects on TSEE from BeO

Oxygen, water vapor and/or carbon dioxide adsorbed on ceramic BeO before or after irradiation profoundly affect the thermally stimulated exoelectron emission (TSEE). In their presence the TSEE is dominated by a single peak at a surface temperature of ∼275°C. Removal of these adsorbates by outgassing during read-out causes the exoelectron emission to intensify with the TSEE curve becoming more complex. Apparently, sorption layers render inoperative certain traps effective for TSEE. Increased temperature during irradiation reduces the response (20% between 22° to 150°C). The influence of the gas surrounding the sample during irradiation was tested for the inert gases helium, nitrogen, neon, argon and krypton using 5.6 keV, 22 keV and 0.66 MeV photons. The enhancement in sensitivity for argon and krypton was much less than expected, which indicates that absorption of radiation in the volume of the solid is more important for excitation of the dosimeter than hitherto assumed.