Optical grade crystals of lithium fluoride (LiF) have been developed f
or high level (50 MGy) and high temperature (250-degrees-C) dosimetry
at GSF, based on optical density (OD) measurements. The measuring accu
racy however was limited by a relatively high coefficient of variation
(20%) for the interspecimen scattering of response. A method is descr
ibed to improve precision by individual probe calibration at a relativ
ely low dose level (1 kGy) by using F-centres only. It is shown that t
he calibration factors are applicable at high doses, where other centr
es are involved. By this procedure, the coefficient of variation for i
nterspecimen scattering can be reduced to less-than-or-equal-to 5%. Th
ermoluminescence (TL) and trace element analysis was performed to find
an explanation for the interspecimen scattering. While no correlation
could be found between optical density and trace element content and
between optical density and TL, a strong correlation was observed betw
een optical density and fluorescence.