A pulse-processor based on rise time measurement of trapezoidal waveforms by using a count-up ADC

In order to raise the throughput of low-energy X-ray signals appearing in a background of high-energy pulses, a new pulse-processor that measures the rising time of a trapezoidal waveform instead of the peak height has been developed. A rectangular pre-filter and a gated integrator are used to make the wave-shape at the shaper output linear. A rectangular pulse is formed by adding a differentiated step signal and its integration. The rising time of the trapezoidal waveform is inversely proportional to the height of the input step pulse. Therefore, processing time for a high-energy pulse is shorter than that for low-energy ones. Consequently, the pile-up loss of the low-energy X-rays is reduced.