Dead time model for X-ray photon counting detectors with retrigger capability

We developed an analytical dead time model able to correctly describe the behavior of X-ray photon counting detectors equipped with retrigger capability, which allows the system to work in non-paralyzable mode by counting the time-over-threshold of piled-up signals in multiples of a predefined and selectable retrigger time. Having an analytical form relating the true interaction rate to the recorded interaction rate will help improving count rate correction routines with respect to the existing techniques, based so far on look-up tables generated through Monte Carlo simulations. The proposed model was validated through comparison with dedicated Monte Carlo simulations. We then used the derived formula as fitting function on a set of more realistic, arbitrary-shaped (non-rectangle) signals, exploring the limits of its validity and proposing an empirical interpretation of the fitting parameters when necessary.