Dose response of radiophotoluminescent dosimeters in low-energy proton beams

Cilj ovog rada bilo je proučavanje odziva radiofotoluminiscentnih (RPL) dozimetara u protonskim snopovima niskih energija. Korišteni dozimetrijski sustav sastoji se od radiofotoluminiscentnog stakla (tip FD-7; dimenzija 16 × 16 × 1.5 mm^2) izvađenog iz držača RPL dozimetara korištenih za zračenja u okolišu (model SC-1; AGC Techno Glass Co) i čitača signala FGD-202. Standardno, prije ozračivanja dozimetre smo anilirali (poništili), a prije samog mjerenja signala stavljeni su u peć na predgrijavanje. Samo ozračivanje odvijalo se na Institutu Ruder Bošković (IRB), gdje smo pomoću dva elektrostatska ubrzivača (akceleratora) (6.0 MV EN Tandem Van de Graaff i 1.0 MV Tandetron) dobili protonske snopove energija 1, 2, 3 i 5 MeV. RPL stakla su tijekom ozračivanja stavljena na prikladna postolja i pomoću držača smještena u vakuumsku komoru povezanu s ubrzivačem. Broj protona zaustavljenih u dozimetrima bio je u rasponu od 3.3 × 10^6 do 1.3 × 10^8 što je odgovaralo dozama u RPL staklu u rasponu od 14.6 do 1464.9 Gy. Rezultati pokazuju da u ispitanom području doza, odziv RPL dozimetra ovisi linearno o dozi do odredene vrijednosti. U linearnom području porast odziva s dozom je strmiji (veći nagib pravca) za veće energije što ukazuje na energijsku ovisnost odziva dozimetra. Izračunata relativna učinkovitost RPL dozimetara raste s porastom energije protona i dobivene vrijednosti su bile u rasponu od 0.103 za protonski snop energije 1 MeV do 0.54, za protonski snop energije 5 MeV.Our aim was to study the dose response of radiophotoluminescent (RPL) glass dosimeters in low-energy proton beams. The dosimetric system used consists of radiophotoluminiscent glass (FD-7 type; dimensions 16x16x1.5 mm3) taken from the casing of environmental RPL dosimeters (SC-1 model; AGC Techno Glass Co) and a FGD-202 reader. Standard annealing procedures were used before irradiation and the dosimeters were preheated in an oven before dosimeter response values were measured. The irradiation took place at Ruder Bošković Institute (RBI), where two electrostatic accelerators ( 6 MV Tandem Van de Graaf and 1.0 MV Tandetron) were used to produce 1, 2, 3 and 5 MeV proton beams. During irradiation, the RPL glasses were mounted on a suitable stand and with the help of a helve, placed inside a vacuum chamber connected to the accelerator. The number of protons stopped inside the dosimeter was in the range between 3.3 × 106 and 1.3 × 108, which corresponds to doses in RPL glass of 14.6 − 1464.9 Gy. The results in the investigated dose range imply the dose response was linear up to a certain value. In the linear range the response increases as the dose increases, more so (greater line slope) at greater energies, which points to an energy dependence of the dosimeter response. The calculated relative effectiveness of the RPL dosimeter increases with increasing proton energy and the obtained values were in the range between 0.103 for 1 MeV proton beam energy and 0.54, for the 5 MeV proton beam energy