Tests performed

• After leaving overnight noticed the pulser was not fully inserted into aida09
  • Little change in rates observed in 9 but otherwise nothing else
• Connected bias of aida02 (n+n ground) to aida06 (n+n ground) and likewise 4-8
  • No change observed in rates
• Also tested covering the snout in light tight material
  • No Changes
• Unplugged the system monitor from 6 and 8, no change
• Connected the snout to ground with copper tape
  • Rates became very unpredictable in the FEEs unsure if this was snout grounding related though
  • Removed the ground and powercycled and rates restored to where previously
• Changed the bias supply jumper inside to have the bias line connected to the rack ground
  • At the same time noticed that the ground cable connecting the adaptor board of aida06 to the FEE had become disconnected from the ring terminal
    • Recrimped and inserted again
  • Saw an improvment in the rates of the p+n strips and also the n+n strips - attachment 1
  • Pulser widths however larger than yesterday

p+n width

n+n width

• Connected up entire pulser circuit to n+n FEEs

Switching bias supply back

• because changes were made to the n+n ground, and the pulser circuit it was decided to go back and check the previous bias configuration with the module set in a floating configuration
• DAQ was then left overnight as had to leave to catch the bus
• Rates are observed to be back at their higher values - attachment 2
• n+n 1.8.L spectra - attachment 3
• p+n 1.8.L spectra - attachment 4

p+n widths

n+n widths

• The results show no improvment to slightly worse performance so will go back to having the bias module grounded internally and check the previous conclusions hold before making further changes

Return to grounded bias module

Widths

p+n

n+n

• Don't see a pulser peak in 4 or 2
• Will replace cable between 4 and 2 and 2 and 6
• Statistics at 0x64 with pulser on - atachment 5
• Now see peaks - attachment 6
• Statistics at 0xa - attachment 7

With the grounded bias in place in the module move the braid cable to the frame rather than being connected to bias line

• Still observe a triple peak in 4 and have worse perfromance in 2 and no improvement in p+n
• 0x64 stats - attachment 7
• 0xa statistics - attachment 8
• p+n 1.8.L - attachment 9
• p+n waveform - attachment 10
• n+n waveform - attachment 11
  • Same high frequency component in both
  • 35 channel spacing corresponds to a frequency of ~1.4MHz

Next tests

• Returned braid to FEE 4 and 8
  • Recovered earlier rates and performance
• Re-added the ground cable to the snout
  • Much worse noise performance across all FEEs
  • p+n rates in 200k
• Removed the ground from the snout
  • Got really good rates originally - attachment 12
  • Noticed 1 and 5 failed ADC calibration
  • Calibrated them and there rates increased massively - attachment 13
• Notice that the pulser peak in FEE2 and 6 keeps dropping out
  • As the cables have been changed multiple times thought it could be that an adaptor board was broken
  • 4 seemed the most likely suspect with its high rates and triple peaks
  • Replaced the adaptor board with one missing an outer ERNI pin (PIN doesn't interface with the FEE so didn't see any issues)
  • Pulser peaks were still muissing
  • Issue could be then with adaptor board 2 possibly

Conclusions

• Rates on the FEEs are in a better place now than they were at the start of the week
  • p+n in particular have shown a large amount of improvement
• There are still however issues with the n+n FEEs
• I think there is likely an issue with one of the adaptor boards
  • Possible aida02 at the pulser connection point
  • Could explain the triple peaking in aida04 and the pulser issues with aida02 and aida06 dropping out.
  • Would recomend swapping out aida02 as a test next week
• Other possible issues coiuld be the clingfilm around the cables has torn and we are grounding the cables to the inside of the snout
  • Nic would like to use something other than clingfilm in future
  • One suggestion would be mylar which could be held in place with strips of double sided tape
  • This would make the cables less likely to stick to each other which is an issue with the tightness of the snout
• Could also try removing LK3 from FEE3 and 7 leaving the PCB ground floating
• I am at a slight loss of what else to try

• I have left the daq running at 0x64 overnight to check for alphas
• Histograms and statistics zeroed