Dichromate dosimeter

The dichromate dosimeter solution is of importance mainly for radiation sterilization and food irradiation applications both for gamma and electron dosimetry. Due to its very good reproducibility, the system is classified as a reference standard system (ASTM E 2628-2009) in the 5-50 kGy dose range and used widely also as a transfer standard dosimeter. 

A personal NO dosimeter employs trapping of the gases on a glass filter impregnated with sodium dichromate and sulfuric acid (NO is oxidized to NO2), followed by passage of the NO2 through a silicone rubber membrane into an acidic solution of hydrogen peroxide in which nitrate is formed and measured by a nitrate ISE. 

This dosimeter relies on the radiolytic reduction of the dichromate ion (Cr207) to chromic ion in aqueous perchloric acid solution. In this aqueous solution the radiolytically produced hydrogen atoms reduce Cr(VI), while the hydroxyl radicals oxidize Cr. Matthews (1981) suggested adding silver ions to the solution, since these scavenge the oxidizing hydroxyl radicals. 

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