A new simulated neutron workplace field at PIAF

The range of neutron energies encountered at workplaces extends from 10−2 eV to 107 eV or even higher neutron energies. The monoenergetic neutron calibration fields cover the neutron energy range from 104 eV to 107 eV. Hence calibrations in so-called realistic fields with a broad spectral distribution similar to those at workplaces are still essential for radiation protection equipment.This is the reason why PTB has developed a simulated workplace field. The field is produced using a proton beam on a thick Li or Be target installed in a moderating sphere which produces the intermediate and thermal part of the spectrum. Different target materials and compositions and different constructions of the target were investigated with special focus on the long-term stability of the neutron yield, as well as the stability of the spectral neutron fluence of the primary neutron spectrum. The spectral distribution outside the moderator sphere was measured using the PTB Bonner sphere spectrometer NEMUS and calculated using MCNPX.