Detection efficiency of fission tracks in apatite related to mica external detectors by the spike irradiation technique

Detection efficiency of fission tracks in non-annealed and annealed Durango apatite crystals related to mica external detectors for fission track dating was estimated experimentally using the spike irradiation technique [Suzuki, 2002a. s of 21st International Conference on Nuclear Tracks in Solids, p. 22]. The relation of the fission track density between apatite samples and mica external detectors is an important parameter for the determination of fission track ages using an absolute approach especially for crystalline minerals. Spike irradiation of uranium-235-induced fission fragments was carried out using a high uranium content glass, GE1497, fixed firmly on the sample surface. Experimental works were carried out for sections parallel and perpendicular to the crystallographic c-axis of apatite. The detection efficiency of fission tracks in non-annealed apatite related to the mica external detectors was estimated to be 0.90 for the prism face and 0.99 for the basal face. The fission track age of Durango apatite averaged for the prism and basal faces was estimated to be 30.6 (±2.5) Ma, which is concordant with reference values reported previously, using the detection efficiency data with a B0 value of the CN5 monitor glass and a U-238 spontaneous decay constant value of 8.46×10-17a-1. The results also indicate that the B0 age calibration method can be used effectively for the absolute evaluation of fission track ages of apatite.