Effects of γ-irradiation on the electron lifetime and positive ion mobility in tetramethylsilane and tetramethylpentane

Abstract Two possible room-temperature liquids suitable for calorimetry, tetramethylsilane (TMS) and (2, 2, 4, 4) tetramethylpentane (TMP) were irradiated with γ-radiation of a 60 Co source up to doses of 1 Mrad and 10 Mrad, respectively. Electron lifetime and mobility of positive ions were measured as a function of radiation dose at two different dose rates. The liquid samples were kept in sealed ionization chambers made of stainless steel and ceramic. A decrease of electron lifetime with increasing dose was observed, which is attributed to the formation of compounds with double bonds. In TMP the positive ion mobility changed with irradiation, probably owing to the formation of high-molecular-weight compounds.