Search for noise sources Nuno Barros FNAL, Feb 24, 2016 1 Notes - - PowerPoint PPT Presentation

Search for noise sources

• Nuno Barros

1

FNAL, Feb 24, 2016

• FEMB8-11 has not been extensively tested as 2 ASICs

show to be current limited (drawing 1.5 A / max)

• I’m writing a small report on all tests performed over the

last 2 weeks (~2k runs taken)

2

Notes

• Turn on the ASICs with ~30 s interval
• Spikes in power observed each time
• FEMB15 and FEMB12 often induce an unrecoverable spike (run with noise)

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Reproducible noise situation

• Turn on the ASICs with ~30 s interval
• Spikes in power observed each time
• FEMB15 and FEMB12 often induce an unrecoverable

spike (run with noise)

• If ASICs are powered “quickly” one after the other, the

noise situation occurs less often

• Seems to suggest some capacitance in the system

4

Reproducible noise situation

• Once noise is induced by FEMB12-15 it spreads over

the whole detector

• Tests tried:
• Induce noise in FEMB12-15, take a run and then

turn on FEMB0-3

• Repeated with FEMB4-7 and FEMB12-15
• Only FEMB12-15 seems to be induced into noise by the

“spaced” powering up

• Tried FEMB0-3 and FEMB4-7

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Related observations

• Take data with different ASIC configurations (gain and shaping time)
• Sometimes when changing the configuration the runs would become noisy.
• No particular pattern observed
• Most likely related to the auto configuration of the ASICs every time the

DAQ is initialized (and the related spike in the power that is observed)

• Take data with only drift voltage for long period (about 8h)
• No problems
• Take data with only bias voltage for long period (about 4h)
• No problems
• But detector became noisy when ramping up the drift voltage

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Other tests

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Changes in power during normal operation

Initialize Start run

• Managed to recover from a noise condition twice
• Powering off FEMB14

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Curious observation

• Keep testing how to induce the noise
• Look for other noise sources
• This does not explain everything
• Try to understand whats going on with FEMB12-15
• Tests done so far show this is consistently the source
• f noise.

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Next steps