Advancements in accuracy of the alanine dosimetry system. Part 2. The in ̄uence of the irradiation temperature

Systematic measurements of the temperature coecient for alanine electron paramagnetic resonance (EPR) response have been performed for irradiation in the temperature range (10±50)8C and in the absorbed dose range (1±100) kGy at the dose rate 9.5 kGy/h. During the Co -ray irradiation, -L-alanine dosimeters were kept in a sealed aluminum holder that provided an e€ective heat exchange with the temperature-controlled environment. The time between the irradiation and signal measurements was standardized, and a reference sample ®xed in the resonant cavity was used to correct the signals for small variations in the spectrometer sensitivity. The temperature coecient for each dose was determined from approximately 30 experimental points processed by the weighted least-squares technique after the necessary statistical tests were done. The temperature coecients thus determined were considerably lower than previously reported. The dose dependence of the temperature coecient features a minimum at (20±30) kGy (about 0.135%/K) with higher values at 1 kGy (0.17%/K) and at 100 kGy ((0.175±0.19) %/K). With the exception of very high doses, no signi®cant distinction was found between the temperature coecients of Bruker and NIST dosimeters, which di€er in shape and binder content. # 1999 Elsevier Science Ltd. All rights reserved.