CDC old & new preamp noise scope trace study
A study was performed using three preAmps:
- Yves' old preAmp : the old preamp that changed behavior a month ago
- Beni's old preAmp: the old preamp used before by Beni.
- Naomi's preAmp : the new preAmp.
Left is always Yves' old preAmp, middle is Beni's old preAmp, right is Naomi's new preAmp [except mentioned differently]
First 2000V was put on the chamber and a random cosmic ray signal was selected:
OK, so far so good. Let's switch the HV off and look at the ringing: the highest amplitude ringing was selected,
so you are looking at the high end of the pedestal:
Channel 1
Channel 8
Channel 9
Channel 15 <- This channel is always used for Fe-55 measurements
The old preAmp has higher amplitude noise in chip2 -> channels 9-16 The new preamp has lower amplitude ringing compared to the old preAmp.
Now it comes: wierd peaks (see below) are seen in the Fe-55 spectra in yves' old preAmp and Beni's old preAmp. This is because those when those spectra are taken the straw is self triggering.
This is how it looks on the scope: (the new preAmp did not show this behavior) Channel 1
Channel 8
Channel 9
Channel 15 <- channel used for Fe-55 measurements
