Colour Centres in LiF for Measurement of Absorbed Doses up to 100 MGy

Abstract

Radiation damage studies on electronic components, polymers, composites, ceramics, metals, and insulating materials exposed to very large doses of ionising photons and particles (i.e. electrons, protons, and neutrons) require reproducible and accurate passive dosimetry. Absorbed doses in the range 10 2 -2 x 10 6 Gy have previously been measured with optical quality, undoped LiF by spectrophotometry of radiation-induced absorption bands of stable colour centres. These include the relatively stable F centre (247 nm), M centre (443 nm), R 1 centre (315 nm), R 2 centre (374 nm), and N 2 centre (547 nm). It is now possible to extend this range to 10 8 Gy by spectrophotometry of the N 1 centre (517 nm) and an 'X' centre (785 nm). These dosemeters can be used from cryogenic (4 K) to relatively high radiation temperatures (up to 500 K). The radiation-induced coloration can be bleached for re-use of the dosemeters by a two hour thermal annealing treatment at 830 K.