Polycarbonate Track Detectors with a Flat Energy Response for the Measurement of High Energy Neutrons at Accelerators and Airflight Altitudes

Abstract

For the polycarbonate detector routinely used at FZK, the two-step electrochemical etching was finally optimised after changing the detector thickness from 300 μm to 500 μm 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 Makrofol is now 130 tracks.cm -2 .mSv -1 within ± 30%. The linearity of detector response has been checked. The increase of the track density due to the neutron component of the natural background radiation at ground level has been measured during 1.5 y. Additional calibrations were performed in broad neutron beams at the PSI and CERN. The detector is suitable for monitoring the long-term occupational exposure at high 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 component of cosmic radiation.