ON THE DETERMINATION OF THE TRACK AGE OF SOME NATURAL CRYSTALS

The detailed investigations of annealing behavior of fission fragment tracks in muscovite mica, apatite and whitlocite crystals have been pe rformed. For muscovite mica the annealing procedure has been applied t o single fission fragment tracks, for apatite and whitlocite crystals - for binary events. As it has been observed, the controlled annealing produced the shortening down of fission fragment track length. Such p rocedure provides more direct comparison of the track length spectra d ue to spontaneous fission of U-238 and due to thermal neutron induced fission of U-235 in the same crystal; it allows one to obtain more cor rect value of the track age.