Measuring neutron fluence and gamma/X-ray fluxes with CCD cameras

The ability to measure bursts of neutron fluences and gamma/X-ray fluxes directly with charge coupled device (CCD) cameras while being able to distinguish between the video signals produced by these two types of radiation, even when they occurred simultaneously, was demonstrated. Volume and area measurements of transient radiation-induced pixel charge in English electric valve (EEV) frame transfer (FT) CCDs from irradiation with pulsed neutrons and Bremsstrahlung photons were utilized to calibrate the devices as radiometric imaging sensors capable of distinguishing between the two types of ionizing radiation. Measurements indicated ≈0.5 V/rad responsivity with ⩾1 rad required for saturation from photon irradiation. Neutron-generated localized charge centers or peaks binned by area and amplitude as functions of fluence in the 10⁵ to 10⁷ n/cm² range indicated smearing over ≈1 to 10% of the CCD array with charge per pixel ranging between noise and saturation levels