Validation of the stamping method for CaSO4:RE + Teflon® pellets production

Abstract

The IPEN method for the CaSO₄:RE + Teflon^® production, developed and patented at the Dosimetric Materials Laboratory – LMD/IPEN in the earlier 1980’s, [1] is highly time-demanding, so that the use of the stamping method, already widely industrially applied, would enhance the CaSO₄:RE + Teflon^® pellets production. Thus, validating the stamping method, by comparing the dosimetric properties of a batch of pellets produced by each method, became a must. The stamped batch presents the same mean non-irradiated signals either after sintering or annealing while IPEN batch mean non-irradiated signals vary in 23%. The mean TL signal after irradiation was about 50 nC, but the standard deviation varies from 20% to 33% for IPEN batch and keeps in 10% for the stamped batch. 24 h after the irradiation, the TL signal decreased to about 35 nC, with no differences in IPEN batch standard deviation and a decrease to 5% in stamped batch standard deviation, for the five performed essays. Calibration curves present a linear behavior over the entire studied dose range and the same coefficients for both methods, however, the uncertainties in the coefficients determined to the calibration curve obtained with stamped pellets are significantly smaller, leading to a more precise dose determination. This results show that the stamping method produces more homogeneous batches, with pellets that maintain the dosimetric characteristics of the detectors produced by IPEN method, in such a way that the stamping method can substitute with advantages the IPEN method in the CaSO₄:RE + Teflon^® dosimetric pellets production.