1 S4 Environmental Disturbances Robert Schofield, U of O John Worden, Richard McCarthy, Doug Cook, Hugh Radkins, LHO Josh Dalrymple, SU I.Pre-S4 “fixes” II.Some S4 veto issues III. 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 produces beam-axis motion produces 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 2.1 Hz prediction ~ agrees, but 1.2 doesn’t Predicted cutoff ~12 Hz

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

10 Up-conversion with injection to mimic pitch during wind Optical lever during periods of wind, quiet and actuator injections to “match” wind 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 ETMX LHO ITMY (due to MICH) Brian’s LLO ETMX measurement

14 S4 H1-H2 coherence peak identification for Stochastic group 133 Hz: Neslab PSL chillers330 Hz HVAC turbine SF01

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

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

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

Hz peak goes away when power supply fan disconnected.

19 Summary I.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?) II.Some S4 Issues a. Up-conversion of low frequency “continuous” seismic noise b. Veto up-converting Hz seismic transients c. Continuous environmental sources can produce AS_Q bursts III.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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