EFFECT OF LOW IRRADIATION TEMPERATURE ON THE GAMMA-RAY RESPONSE OF DYED AND UNDYED PMMA DOSIMETERS

Temperature effects on dose responses of undyed and dyed polymethylmet hacrylate (PMMA) dosimeters were studied at doses of 2 and 25 kGy unde r irradiation temperatures from -196 degrees C to +45 degrees C. At 25 kGy, Radix RN15 has linear dependence with a coefficient of +0.15%/de grees C and +0.25%/degrees C for irradiation temperature below and abo ve -15 degrees C respectively, and Red 4034 and Amber 3042 have smalle r dependence in this temperature range, although Red 4034 has relative ly high responses at -196 degrees C and -78 degrees C. At a dose of 2 kGy, dose response of Amber 3042 increases nearly linearly with temper ature above -78 degrees C with a coefficient of about 0.5%/degrees C. The dose response of Gammachrome YR below -78 degrees C is almost 30% higher than that at 20 degrees C and decreases with increasing tempera ture above -78 degrees C with temperature coefficient of -0.3%/degrees C. Copyright (C) 1996 Elsevier Science Ltd