Measuring neutronfluences and gamma/x-ray fluxes with CCD cameras

This paper reports on the capability to measure bursts of neutron fluences and gamma/z-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 occur simultaneously. Volume and area measurements of transient radiation-induced pixel charge in English Electric Valve (EEV) Frame Transfer (FT) charge coupled devices (CCDs) from irradiation with pulsed neutrons (14 MeV) and Bremsstrahlung photons (4-12 MeV endpoint) are utilized to calibrate the devices as radiometric imaging sensors capable of distinguishing between the two types of ionizing radiation. Measurements indicate ∼ 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 indicate smearing over ∼ 1 to 10% of CCD array with charge per pixel ranging between noise and saturation levels