POLYCARBONATE TRACK DETECTORS WITH A FLAT ENERGY RESPONSE FOR THE MEASUREMENT OF HIGH-ENERGY NEUTRONS AT ACCELERATORS AND AIRFLIGHT ALTITUDES

For the polycarbonate detector routinely used at FZK, the two-step ele ctrochemical etching was finally optimised after changing the detector thickness from 300 mu m to 500 mu m and applying a field strength of 42 kV.cm(-1). On the basis of calibrations with monoenergetic neutrons in the neutron energy range from 2 to about 70 MeV the response of Ma krofol is now 130 tracks.cm(-2).mSv(-1) within +/-30%. The linearity o f detector response has been checked. The increase of the track densit y due to the neutron component of the natural background radiation at ground level has been measured during 1.5 y. Additional calibrations w ere performed in broad neutron beams at the PSI and CERN. The detector is suitable for monitoring the long-term occupational exposure at hig h energy particle accelerators and the exposure of the aircrews with a lower limit of detection 0.2 mSv per year. Polycarbonate is the only neutron detector which is insensitive to the high energy proton compon ent of cosmic radiation.