Geometry Factor in Fission Track Dating

An analysis of geometry factor on fission track dating using both the external and internal surfaces of zircon with external detectors is made in this note. The present experimental results suggest that the geometry ratio of track density of an external to that of an internal surface takes G = 0.52. This experimental value agrees with the value of G = 0.53 obtained from the minimum track length proposed by Green and Durrani (1978). A series of experimental results yields that the value of g' (i.e. the ratio of track density in an external detector to that in an external surface) takes 0.98. The fission track ages calibrated by using both G and g' values obtained from track density of internal surface, are approximately coincident with the ages calibrated by only g' value obtained from external surface