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S4 Environmental Disturbances

S4 Environmental Disturbances. Robert Schofield, U of O John Worden, Richard McCarthy, Doug Cook, Hugh Radkins, LHO Josh Dalrymple, SU. Pre-S4 “fixes” Some S4 veto issues Early coupling results from S4 PEM injections. Up-conversion of low frequency seismic noise.

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S4 Environmental Disturbances

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  1. S4 Environmental Disturbances Robert Schofield, U of O John Worden, Richard McCarthy, Doug Cook, Hugh Radkins, LHO Josh Dalrymple, SU • Pre-S4 “fixes” • Some S4 veto issues • Early coupling results from S4 PEM injections

  2. Up-conversion of low frequency seismic noise seismic noise from distant excavation night spectrum excites stack modes in AS_Q up-conversion reduces interferometer sensitivity night spectrum

  3. Optic motion, by itself, does not produce up-conversion. shaking ground at 1.2 Hz moves optic and produces up-conversion larger optic motion from actuator injection does not result in up-conversion

  4. Up-conversion depends on stack motion not floor motion. Small shaker on cross-beam and large shaker on floor adjusted to produce similar optic motion... ...produce similar up-conversion even though floor motion differs by 10.

  5. Ground shaking to excite specific motions Red: mainly beam-axis; Blue: mainly side-to side; Black: no shaking Beam-axis (AS_Q) Yaw (from optical lever) Pitch (optical lever) Side (from shadow sensor)

  6. Side-to-side shaking does not produce up-conversion. Ground shaking that producesbeam-axis motionproduces up-conversion, but shaking that produces side-to-side motion does not.

  7. Up-conversion for different shaking amplitudes Small fast-traveling seismic transient

  8. Simple model doesn’t work at all frequencies Predicted cutoff ~52 Hz Predicted cutoff ~12 Hz 2.1 Hz prediction ~ agrees, but 1.2 doesn’t

  9. Possible sources of up-conversion brushing cables on test mass support structure output telescope: consistent with lack of up-conversion for side-to side

  10. Up-conversion with injection to mimic pitch during wind Optical lever during periods of wind, quiet and actuator injections to “match” wind. 70-100 Hz band in AS_Q showing up-conversion during wind and actuator injection.

  11. Wind-simulating injection produced RF saturation Small fast-traveling seismic transient

  12. Wind likely produced saturation and “mystery” up-conversion. Black: wind; Red: ETMY 1.2 Hz pitch injection; Blue: quiet Up-conversion from wind differs from up-conversion from injection; wind still produced up-conversion at lower power.

  13. Up-conversion at different locations, similar velocities LHO ITMY (due to MICH) LHO ETMX Brian’s LLO ETMX measurement

  14. S4 H1-H2 coherence peak identification for Stochastic group 133 Hz: Neslab PSL chillers 330 Hz HVAC turbine SF01

  15. Pulsars in VME crates magnetometer near VME crate detects pulsar candidate frequencies. Magnetometers elsewhere don’t. Red: normal operation of VME crate Blue: VME crate on, but 7751 CPU board disconnected Black: 7751 CPU on but code not running

  16. Coherence between AS_Q and VME magnetometer 108 Hz peak magnetometer Broad-band coherence

  17. 108 Hz peak moves with air-flow to fans Blue: normal air; Red: extra air

  18. 108 Hz peak goes away when power supply fan disconnected.

  19. Summary • Pre-S4 partial fixes • a. Wandering chiller seismic peak (D.Q. flag for 16 Hz?) • b. 10 Hz from RFID • c. Transformers near test masses (ion pump supplies?) • d. Crab protection (LHO out-stations, LLO?) • Some S4 Issues • a. Up-conversion of low frequency “continuous” seismic noise • b. Veto up-converting 0.7-2 Hz seismic transients • c. Continuous environmental sources can produce AS_Q bursts • Preliminary coupling results from S4 PEM injections • a. LHO LVEA ambient sound level generally less than 1/5 SRD • above 60 Hz • b. LHO out-station ambient sound level generally less than 1/10 SRD • c. 60 Hz peak in AS_Q may be dominated by direct coupling of ambient • magnetic fields

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