Three types, Red 4034, Amber 3042, and Gammachrome YR are made from radiationsensitive polymethylmethacrylate pmma in the form of optically transparent pieces individually hermetically sealed in laminate sachets. They darken when irradiated, and the radiationinduced darkening, accurately measurable by means of a spectrophotometer, is a function of the radiation dose absorbed.

Address: 540 Becquerel Avenue, Harwell Science and Innovation Campus, DIDCOT, Oxfordshire OX11 0RA, United Kingdom
Telephone: 44 (0)1235 435707
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Website: http://www.harwell-dosimeters.co.uk/