Electronic neutron dosimeter in high-energy neutron fields

In neutron fields including neutron energies above 20 MeV a conventional neutron dosimeter is not suitable for measurements of neutron personal dose equivalent, Hp(10), over the whole energy range. Therefore, for such fields an electronic neutron dosimeter has been developed recently at Helmholtz Zentrum Munchen (HMGU). In general, neutron dose measurements performed with this dosimeter at neutron energies below 2 MeV show an accuracy of about 30% [1]. Here we report the use of this dosimeter at the CERN-EU high-energy Reference Field (CERF) facility in Geneva, Switzerland. At this facility the available neutron fields include neutrons with energies below, but also above 20 MeV. In the present paper, personal dose equivalent (Hp(10)) values obtained with the ELectronic neutron DOsimeter (ELDO) are compared to neutron personal dose equivalent (Hp(10)) values obtained with the HMGU extended-range Bonner Sphere Spectrometer, and to reference values from FLUKA Monte Carlo simulations provided by CERF. It is shown that for continuous neutron spectra as those at CERF behind concrete shielding or secondary neutrons from cosmic rays, the dosimeter results are satisfactory for radiation protection purposes. However, in neutron fields including neutrons above about 7 MeV, where the major neutron dose contribution is from neutrons between 10 keV and several MeV (like those at CERF behind iron shielding), the doses provided by ELDO might be too small and care must be taken in interpreting the results.