Influence of Reference Field Spectra on Calibration of Field Class Dosimeters

Abstract

Active electronic dosimeters are usually calibrated in Secondary Standards Dosimetry Laboratories in reference photon fields, with the uncertainty which is typically around 5 % (k=2). Reference fields are established in accordance with relevant international standards – usually ISO 4037 for photon radiation. Some differences in spectra between different laboratories are unavoidable, but the effect on reference dose rates is well studied and within the above mentioned measurement uncertainty, and this is confirmed by existing interlaboratory comparisons. However, many field class dosimeters have poor energy dependence, especially in the energy range below 100 keV, which could cause large differences in calibration factors determined in different calibration laboratories under nominally the same conditions. This may also have implications for dosimeter testing or verification. In this paper, preliminary results obtained in two different calibration laboratories are presented.

Aktivni elektronski dozimetri se najčešće etaloniraju u Sekundarnim standardnim dozimetrijskim laboratorijama u referentnim poljima fotonskog zračenja, sa mernom nesigurnošću od oko 5 % (k=2). Referentna polja se uspostavljaju u skladu sa međunarodnim standardima, obično ISO 4037 za fotonsko zračenje. Male razlike u spektrima u različitim laboratorijama su neizbežne, ali je efekat na referentne vrednosti dobro proučen i ostaje u okviru mernih nesigurnosti, što je potvrđeno postojećim međulaboratorijskim poređenjima. Međutim, mnogi korisnički dozimetri imaju lošu energetsku zavisnost, pogotovo u opsegu energija ispod 100 keV, što može da uzrokuje velike razlike u kalibracionim faktorima određenim u različitim laboratorijama u nominalno istim uslovima. To može da ima posledice i na ispitivanje ili overavanje dozimetara. U ovom radu su prikazani prvi rezultati dobijeni u dve različite laboratorije za etaloniranje.