Using the Reset Preamp Inhibit Signal
The preamp reset event produces a large signal, which drives the amplifier into a se
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vere overload condition. The Model 2016 recovers from overload events rapidly and
monotonically, requiring approximately two non-overload pulse widths to fully re
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cover.
Converting events during amplifier overload may produce spectral distortion and it is
recommended that the SCA and amplifier be gated OFF during this time using the
preamp INHIBIT signal. The preamp INHIBIT signal width should be adjusted to en
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compass the full unipolar signal recovery. The INHIBIT signal from the Model 2101
Transistor Reset Preamp, the Model 2008 Optical Reset Preamp or the Preamp Reset
Module is positive true.
To properly make this adjustment:
1. Set the scope’s vertical sensitivity to 20 mV/div.
2. Using a clamp box, such as the Canberra Model LB1502 Schottky Clamp
Box, connect the Amp Out signal to one of the scope’s inputs.
3. Connect the Inhibit signal to the scope’s other input.
4. Trigger the scope on the leading edge of the Inhibit signal.
5. Adjust the width of the Inhibit signal so that it ends when the amplifier’s
output returns to within 2 mV of the baseline.
Triangular Shaping
The peaking time for triangular shaping is approximately 14% longer than Gaussian
shaping with an equivalent shaping time. The longer peaking time is equivalent to in
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creasing the shaping time. This effectively increases the choice of shaping time con
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stants from 6 to 12 when both shaping modes are considered.
The longer peaking time provides improved signal-to-noise ratio (SNR) and reduced
electronic noise. Triangular shaping is also less sensitive to the effects of detector bal
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listic deficit. Both factors benefit by improved resolution performance. But you should
be aware that the resolution improvement gained, due to the longer overall signal pro
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cessing time, is at the expense of reduced maximum throughput.
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Triangular Shaping
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