Observation of abnormal three- and two-prong events in Canadian biotite

Abstract

One three-prong and two long two-prong events were detected in biotite mica samples from Bancroft, Canada, which had, prior to HF etching, been irradiated with 40 Ar (of total energy 108 MeV) and 32 S (32 MeV) ions. From spatial configurations of the tracks in all of these observed events it is concluded that they had probably resulted from the spontaneous fission of some heavy nuclei at rest. The three-prong events was found to be surrounded by a coloration ring of radius 26.2 μm. If the events are regarded as the result of nuclear reactions of Ar and S projectiles with U and/or Th nuclei in the mica, at energies well below the Coulomb barrier, the cross section of complete fusion must have been extraordinarily high when compared with the production cross sections of elements Z = 104–109 in heavy-ion reactions. Thus the fossil origin of the events cannot be ruled out, although scanning of a large area of the etched unirradiated samples did not show any other unusual event.