Fast neutron and γ-ray dosimetry with imaging plates

An imaging plate (IP) is a passive integrating detector capable of medium-term storage of ionizing energy. A visible laser scan can be used to liberate a number of visible photons proportional to the amount of energy trapped. An IP is sensitive to ionizing particles of any energy, whatsoever, to neutrons and to photons. It is linear in response over 4–5 decades. We have studied the response of IPs to neutrons emitted by Pu–Be and Am–Be sources in differential measurements that correct for the γ-ray component from the neutron source. The dose threshold for fast neutrons, as well as for 60 Co γ -rays, could thus be determined.