Proposed post-S5 investigations

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• Carry out more extensive set of signal hardware injections (better statistics, higher strengths, new waveform morphologies?)
  • Investigate significance of overflows sometimes seen for loud injections (artifact of actuation?)
  • Verify nominal veto thresholds are truly safe
• Carry out more extensive PEM injections (post-S5, following calibration work), including:
  • Stimulate and study indirect H1-H2 couplings (e.g., response to common environmental disturbances)
  • Stimulate and study direct H1-H2 couplings (e.g., study specular reflections)
  • Introduce and study character of dust glitches (e.g., study dust glitches common to all AS photodiodes and particular to individual photodiodes. Introduction could mean merely opening the door and turning the HEPA filter off - filming dust flashes is an option. Adding a photodiode with a wide field of view to catch flashes is another possibility.)
• More spectral line studies, including:
  • Pin down definitively the nominal violin mode frequencies of each large mirror and identify suspected violin modes around 330 Hz. (This information is useful for S6 preparation too.)
  • Identify lines due to power supply ripple at LLO (several days work with occasional VME reboots necessary, but otherwise can go on in parallel with other studies.)
  • Study further the thermal absorption of mirrors via tracking of internal mode frequency changes - couple of days needed for long-time-constant measurements.)
• Calibration and noise budget at the FSR frequency
• Scatterometer measurements and beam spot imaging
• Pin down coupling mechanism of autoburt glitches on L1
• Pin down reason that rack door removal reduces noise (temperature-dependent beating between on-board oscillators suspected)
• Shake all cables (gently!) to check for glitches.
• Carry out extensive upconversion tests (dedicate ~week for integration time for low frequency measurements)
• Investigate PEPI tidal servo - relevant to S6 too.