<p>An apparatus includes an integrator (120) that produces a pulse having a peak amplitude indicative of the energy of a detected photon. First discharging circuitry (136) discharges the integrator (120) at a first discharging speed, and second discharging circuitry (124) discharges the integrator (120) at a second discharging speed. The first discharging speed is less than the second discharging speed.</p>
