MSI-8 and MPR-16 preamps have nominal differential output ranges of +/-1.8V and +/-1.2V respectively at maximum input (ie 5GeV).
All our FEBEX cards are now modified to accept +/-2V range. If serious pileup occurs, this could make it difficult to disentangle events for the n-sides.
To test whether out preamps satisfied this output range, we attempted to calculate the expected height from a 500mV pulser. This should have been:
input height * (pulser coupling range / preamp energy range) * nominal output range
Mesytec noted that all coupling components are only tested to be within +/-10%, including the pulser coupling capacitors. Thus exact testing is challenging.
The pulser inputs of our MSI-8 cards are:
MMPR-1: Pulser inputs:
Type: 2GeV Pulser : 330MeV/V
Type: 5GeV Pulser : 330MeV/V
Type: 20GeV Pulser: 1GeV/V
Thus in the attached table, we can see the 2GeV and 5GeV cards are well within tolerance, but the 20GeV card is a bit outside. Thus we should probably expect a large output range from those cards.
We also tested the MPR-16 cards. However these cards do not have a terminated pulser input, and it is not clear to us what impact that would have. In the attached table, it seems to have a pretty consistent
factor of 4 difference though. |