PROGRESS IN SOLID-STATE FAST NEUTRON PERSONNEL DOSIMETRY.

The poor stability of latent recoil proton tracks in photographic emulsions has frequently been underestimated due to unrealistic testing conditions.Thin polycarbonate foils to be evaluated by automatic spark-counting exhibit no fading for at least three months at 32°C and 95 % humidity.As one of several alternatives to the NTA film, optimized combinations containing 237 Np or' 232 Th and 10ym polycarbonate foils are described ( 237 Np covers a wide dose range of % 10" 3 to £ 10 rad, and neutron energies £ 0.6 MeV).The directional response is given for different neutron energies and detector-phantom distances.Another approach consists of the amplification of recoil nuclei etch pits to facilitate automatic counting.The inherently low fast neutron response of most solid-state detectors can be increased by intimate contact with a hydrogenous material.TSEE detectors based on BeO, for example, which are covered with a hydrogenous radiator, have been used successfully in recent tests of criticality monitoring systems at ORNL.The thin sensitive layer of exoelectron detectors makes this approach especially attractive for intermediate neutron energies.