CR-200-X shaper modules

Shaping amplifiers are often used following the charge sensitive preamplifier stage and perform three functions: First, they provide an output pulse having a much faster return to the baseline than the charge sensitive preamplifier output pulse. This is especially important at high count rates, where pulses from consecutive events can ‘pile up’. Secondly, shaping amplifiers filter noise from the preamplifier output signal. Finally, shaping amplifiers can also be used to provide extra gain to the signal, which may be very small (sub mV) at the preamplifier output.

In the example below, two oscilloscope traces are shown: the input (blue) and output (yellow) of a shaping amplifier (1μs shaping time) reading pulses from a charge sensitive preamplifier in the presence of noise. Not only does the shaping amplifier amplify the small pulses, but more importantly the fall time is quickened, greatly reducing the problem of pulses ‘piling up’ on the tails of preceding pulses. Also, the filtering effects of the shaping amplifier significantly filters the noise. This allows for pulses to be clearly detected that would be otherwise completely buried within the noise.