Exposing radiochromic film with strontium-90 beta particles

Sheets of Gafchromic EBT3 radiochromic film are exposed to radiation from a strontium-90 pterygium eye applicator, causing the dye in the film to polymerize into its characteristic blue form. The influence of a magnetic field is investigated. In total, three sheets are irradiated for one hour each: 1) with no magnet present; 2) with the magnet in one orientation; 3) with the magnet in the reverse orientation.