Run 4848:
- HVs for 1--10 on, pulser on
- LED #5, #10 plugged in
- Pedestal run
- T8 trigger dominated (others prescaled away)
= Noise present on ADC inputs 1, 2 (2nd and 3rd)
Run 4849:
- Pedestal run
- T8 trigger dominated (others prescaled away)
- swapped 60Hz filter at ADC: WAS #6, now a new filter "#12"
= No effect on noise at input 1, 2
Run 4850:
- Pedestal run
- T8 trigger dominated (others prescaled away)
- swapped signal inputs 0, 1 at the patch panel just upstream of
the ADC
= Noise followed the cable
Run 4851:
- Pedestal run
- T8 trigger dominated (others prescaled away)
- swapped signals back to original inputs
- HV off on 2nd PMT (ADC input 1)
= Noise is still there (unaffected by HV on/off)
Run 4852:
- Pedestal run
- T8 trigger dominated (others prescaled away)
- HV still off on 2nd PMT (ADC input 1)
- swapped signal cables right at the PMTs for PMT 1, 2
= Noise unchanged (i.e. NOT coming from the PMT/base)
Run 4853:
- Pedestal run
- T8 trigger dominated (others prescaled away)
- HV still off on 2nd PMT (ADC input 1)
- signal cables swapped back at the PMTs (now normal)
- swapped signal cables right at the front-end electronics
amplifier inputs for PMTs 1, 2
= Noise stayed on same ADC channels, but the right-edge amplitude
went from channel 400 to 600... The little peak around channel
110 also seems suppressed now.
= ADC channel 0 has _no_ noise in it, not even the low-level
'normal' background. It is now viewing PMT 2 that has the HV
turned off.
Run 4854:
- same setup as 4853, just jiggled the cables a bit before
rerunning to make sure they're seated.
= same results as 4853
Run 4855:
- same setup as 4853, but HV OFF on PMT 1 now (as well as off on
PMT 2)
= No effect
Run 4856:
- ALL HVs turned OFF, signals 1,2 still swapped at FE amplifier.
= No effect on noisy ADC inputs 1, 2, but no background noise in
ADC 3 channel any more (it goes away when the associated PMT HV is
Off).
= It looks like the problem is downstream of the FE amplifier, and
upstream of the ADC.
[ Fed pulser into PMT 2 signal cable at PMT to confirm where the
signal came out at the DAQ weldment, Pulser stayed unplugged after
this. ]
Run 4857:
- ALL HVs turned OFF,
- signals 1,2 swapped back at FE amplifier (normal now)
- swapped the PMTs signals at the first patch panel at the DAQ
weldment (ie. cables E-01R and E-02R).
= noise was on ADC 0, not on ADC 1
Run 4858:
- ALL HVs turned OFF,
- swapped back the PMTs signals at the first patch panel at the
DAQ weldment (all back to normal now)
= ALL noise went away now... everything looks good... weird.
Run 4859:
- ALL HVs turned OFF,
- swapped signal cables 1,2 at the the first patch panel at the
DAQ weldment again (same as run 4857)
= Everything is still clean. Problem solved itself... Bad
cable, flaky connection, who knows...
[ Plugged pulser back into PMT 20's LED input. This is the
configuration from run 4857. ]
Run 4860:
- ALL HVs turned OFF,
- pulser plugged back in to LED input on PMT 20 (now the same as
for run 4857)
- signal cables 1,2 still swapped at the the first patch panel at
the DAQ weldment (same as run 4857)
= noise is back on ADC inputs 0 and 2
Run 4861:
- ALL HVs turned OFF,
- signal cables 1,2 swapped back at the the first patch panel at
the DAQ weldment
- all signal cables back where they should be
= all noise is gone again...
Run 4862:
- repeat of 4860 configuration
- cables 1,2 swapped at DAQ weldment PP
= noise is back on ADC inputs 0 and 2
Run 4863:
- repeat of run 4859
- pulser unplugged from PMT 20 LED input again
= noise remains (contrary to run 4859)
Run 4864:
- cables 1,2 swapped back at DAQ weldment
- all signal cables back to normal again.
- this is the same as 4861, but with pulser unplugged from PMT 20
LED input
= all noise is gone again...
Run 4865:
- second run with 4864 config (no changes at all)
= still clean (no noise)
Run 4866:
- turned on HV for PMT 2 only
= noise back on ADC channels 1 and 2
Data are inconsistent... Not sure where the problem lies. Will try again
tomorrow.