The Authors of this paper have taken part in interlaboratory comparison experiment for the 1988 Fission Track Dating Workshop held in Besancon. Data obtained by the fission track group of Pisa are shown in tab. 1. The results of the experiment recently published by Miller et al. (1990) support these conclusions: - 3 out of 4 samples, 88-1, 88-3 and 88-4, seem to be adequate for interlaboratory comparison. Sample 88-2 seem to be affected by some characteristics which produce a wide range in measured ages; - the absolute calibration based on lambda <sub>F</sub> = 8.46 X 10 (super -17) a (super -1) and neutron dosimetry by metal monitors (Au, Co) produces systematically underestimated ages; - one of the characteristics which produces a wide range in measured ages of apatite 88-2 is the large intergrain uranium content fluctuation; POP and SUB ages obtained by few tens of grains present a very large standard deviation; - the standard error of some of the ages seems to be greatly underestimated; - there is an evident correlation between most of the EDM-Zeta ages of apatites 88-2 and 88-3 reported by the same analysts, very probably due to some bias inherent in this dating strategy.

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