CDC Preamplifier Conclusion

Conclusions on the ASIC Preamplifier

After discovering that the gas mixing system at CMU had malfunctioned, we switched to a premixed 90/10 Ar-CO2 mixture. Using the premixed gas, we were able to reproduce the observed behavior of old preamplifier. We then proceeded to compare the new preamplifier with the old preamplifier.

1. The gain of the new preamplifier is about a factor of

two smaller than that of the old preamplifier.

1. We also observed that the output range of the old preamplifier was from 0V to 1V. E.g. we mapped 1V onto ~4000 channels in the FADC. The new preamplifier has an output range of 0V to 0.5V, with 0.5V being mapped onto ~4000channels in the FADC. This change was made to match the new 72-channel 125MHZ FADC.

PreAmp tests with premixed 90/10 Ar/CO2 - software threshold