Radiation dosimetry with acetylene

Abstract

The suitability of acetylene as a gas-phase radiation dosimeter has been studied. Yields were obtained on an absolute basis, using ionization current dosimetry. Radiolysis of acetylene produces two products, benzene and polymer. The yield of benzene is dependent on dose, dose rate, presence of hydrogen or free radical scavengers, and temperature, and is of no value for estimating dose.     For ⁶⁰Co γ irradiation at a dose rate of 4.1 x 10¹³ eV cm^-3 mmHg^-1 hr^-1 and acetylene pressure 500 mmHg (6.6x10⁴ N m^-2) at 30°C, G(-C₂H₂) = 82.1±0.5.     1-MeV electron irradiation at a dose rate of 3.9 x 10¹⁶ eV cm^-3 mmHg^-1 hr^-1 gave a much lower yield, G(-C₂H₂) = 55.0±1.9, believed to be due to a dose rate effect. G(-C₂H₂) increased by about 67% when the temperature was increased from 25°C to 125-250°C.     Comparison with ethylene indicates the latter is the more useful dosimeter, as the yields do not vary significantly over a wide range of dose rates and temperatures.