S3 ENVIRONMENTAL DISTURBANCES

Transcription

1 S3 ENVIRONMENTAL DISTURBANCES Acoustic Mitigation Update, Gravel Truck Bursts, Dust Bursts, and Pulsed Heaters Robert Schofield, University of Oregon AND MANY OTHERS

2 During S3 PEM injections (with predicted displacement noise from ambient sound) m or GPa / sqrt(hz) Acoustic coupling, H & H *T0=07// :29: *Avg=0 *BW= Hz ramped sawtooth played through speaker. Possible dust glitch at low f in H spectrum H0:PEM-LVEA_MIC H:LSC-AS_Q H2:LSC-AS_Q HPredictedAmbient H2PredictedAmbient SRD L coupling levels were about as bad as H2 around 00 Hz, but as good as H at higher frequencies For H, we have reached our goal (a factor of 000 improvement), but bar has been raised for H & H2 to improve stochastic b.g. upper limits. 4

3 CURRENT COUPLING LOCATIONS AND SEVERITY FROM PROPAGATION DELAYS Acoustic burst near H PSL: Time series H0:PEM-PSL_MIC H0:PEM-ISCT_MIC Signal Time (s) T0=2/0/ :59:55 Avg= Time series 0.3 H:LSC-AS_Q Signal Time (s) T0=2/0/ :59:55 Avg= 5

4 S3 coupling sites ranked by severity, strongest coupling first H: reflected port table PSL table H2: dark port reflected port table L: reflected port table or input optics table (I would guess REFL) Recent investigations of H reflected port table and PSL table suggest that, in both cases, injections near the periscope produce the strongest AS_Q signal. 6

5 LOW FREQUENCY COUPLING, and predicted displacement noise from ambient sound levels. 5 Hz ramped sawtooth played through large woofer 0m from ISCT4: m or GPa / sqrt(hz) H Low Frequency Acoustic Coupling H:LSC-AS_Q H0:PEM-LVEA_MIC PredictedAmbient PredAmbDifferentLoc SRD *T0=06/02/ :0:00 *Avg=5 *BW=

6 What can be done to reduce acoustic contribution to noise at low frequency? HVAC is main source, shutting it off reduces acoustic and acceleration levels by only about 5 though, and indications are that in-duct mufflers would not help - much of it comes directly through wall of mechanical room. Enclosures don t help much at these low frequencies; ours reduce the sound level by about 3, but the accelerations on the table by less than that. Floating legs may be best hope for reducing low f acoustic-seismic coupling. 8

7 COMPARISON OF RIGID AND FLOATING TABLE LEGS ON ISCT3 Red: current leg; Orange: tall tripod; Blue: minus-k; Black: pneumatic Rigid Legs normal leg 34" tripod leg Floating Legs minus-k leg air leg Displacement [m/hz /2 ] Frequency [Hz] Sum in quadrature of 3 accelerometer axes, converted to displacement 9

8 GROUTING OF RIGID LEGS REDUCES RMS VELOCITY BY ABOUT 5 Displacement spectra from accelerometers on ISCT4: red: before caulking, blue: after 0-8 ) 0-9 /2 Magnitude (m/hz H0:PEM-ISCT4_ACCX(REF6) H0:PEM-ISCT4_ACCY(REF8) H0:PEM-ISCT4_ACCZ(REF0) H0:PEM-ISCT4_ACCX H0:PEM-ISCT4_ACCY H0:PEM-ISCT4_ACCZ 0 2 *T0=07/02/ :37:8 *Avg=0 BW= Before recommending grouted rigid legs: ) decide if the displacement spectra are better, or at least as good as, for current legs, 2) try grouting current legs? Floating legs best in velocity and amplitude by about 0; ready to be tested on ISCT3.

9 RECOMMENDATIONS I. REDUCE CONTINUOUS SOURCES (factor of 3 to 5) A. Continue with plans to acoustically house or remove electronics cabinets B. Insulate pipe-feed through from mechanical room C. Insulate PSL chillers II. REDUCE COUPLING (factor of 5 for H & L, less for H2) A. Clipping ) Replace AS and REFL periscopes with V3 of new design 2) Enlarge or remove /2 lambda plate and polarizer in REFL path 3) Damp PSL periscopes 4) Damp mounts and dumps etc. 5) Continue testing floating legs for low f B. Backscattering from table (out of prudence - we haven t seen coupling) ) Grouted damped rigid legs, unless interferes with clipping reduction above III. ACOUSTICALLY ISOLATE WORST COUPLING SITES A. REFL port enclosures with internal absorption kits? Reevaluate after above REFL work. 2

10 DURING S3, GRAVEL TRUCKS CAUSED IN-BAND AS_Q GLITCHES AND LOCK-LOSSES 3 Lock losses correlated with minute scale spikes in 3-0 Hz band M I N Actual Trend Data available from to Trend Ch 7: H:DMT-LOCKLOSS_BOTHarmsLOCK 0.8 None :5: :00: :45: :30: Trend Ch 4: H0:PEM-LVEA_SEISZ_3-0Hz None :5: :00: :45: :30:00 Culprits determined by training video camera on SR0; largest events were gravel trucks

11 Trucks also produce in-band noise by upconversion 64 second spectra; RED: seismometer; BLUE: AS_Q; SOLID: truck; DASHED: no truck Power spectrum 0 Magnitude H0:PEM-LVEA_SEISX H:LSC-AS_Q H0:PEM-LVEA_SEISX(REF0) H:LSC-AS_Q(REF3) *T0=03/2/ :38:35 *Avg=5/Bin=2L BW=0.875 Suggestion: veto periods when 3-0 Hz band of H0:PEM-LVEA_SEISZ exceeds 000

12 Power spectrum H0:PEM-LVEA_SEISX H0:PEM-LVEA_SEISX(REF0) 0 Magnitude *T0=03/2/ :38:35 *Avg=5/Bin=2L BW=0.875 Power spectrum 0 3 Magnitude H:LSC-POB_I H:LSC-POB_I(REF4) *T0=03/2/ :38:35 *Avg=5/Bin=2L BW=0.875

13 DUST CAUSES BURSTS IN AS_Q H AS_Q 6 sigma glitch rate after ISCT4 entry during S3 (3 day trend): M E A N Actual Trend Data available from to Trend Ch 3: H:LSC-AS_Q_DQGlitch_6_ None :00: :00: :00: :00:00 Dust monitor was installed after S3; dust count after ISCT4 entry (3 day trend): M E A N Actual Trend Data available from to Trend Ch 5: H0:PEM-LVEA_DST4_ unknown :00: :00: :00: :00:00

14 RED: spectra for dust flash times on video tape of AS_Q photodiode region; BLUE: spectra OFFSET +/- 0 s from dust flash on video tape Power spectrum Magnitude H:LSC-AS_Q(REF0) H:LSC-AS_Q(REF) H:LSC-AS_Q(REF2) H:LSC-AS_Q(REF3) H:LSC-AS_Q(REF4) H:LSC-AS_Q(REF5) H:LSC-AS_Q(REF6) H:LSC-AS_Q(REF7) *T0=5/0/ :24:24 Avg=5 BW=.5 Power spectrum Magnitude H:LSC-AS_Q(REF8) H:LSC-AS_Q(REF9) H:LSC-AS_Q(REF0) H:LSC-AS_Q(REF) H:LSC-AS_Q(REF2) H:LSC-AS_Q(REF3) *T0=5/0/ :28:7 Avg=5 BW=.5

15 Near periscope where beam is much larger Red: dust flash; Blue: offset from flash Power spectrum Magnitude H:LSC-AS_Q(REF4) H:LSC-AS_Q(REF5) H:LSC-AS_Q(REF6) H:LSC-AS_Q(REF7) H:LSC-AS_Q(REF8) H:LSC-AS_Q(REF9) H:LSC-AS_Q(REF20) H:LSC-AS_Q(REF2) *T0=5/0/ :46:37 *Avg=5 BW=.5 So dust produces large glitches when it passes through small beams.

16 DURING S3, HZ SPACED SIDE BANDS AROUND 60 Hz STARTED TO APPEAR IN AS_Q LLO: Power spectrum 0 L0:PEM-EY_MAGY L0:PEM-EX_MAGX L0:PEM-LVEA_MAGY L:LSC-AS_Q Magnitude T0=3/2/2003 3:00:00 Avg=00 BW= Coherence 0.8 L0:PEM-EX_MAGX / L:LSC-AS_Q L0:PEM-EY_MAGY / L:LSC-AS_Q L0:PEM-EY_SEISX / L:LSC-AS_Q Coherence T0=3/2/2003 3:00:00 Avg=00 BW=0.0787

17 LHO: Power spectrum H:LSC-AS_Q H0:PEM-BSC9_MAGX H0:PEM-BSC0_MAGX Magnitude T0=08// :30:00 Avg=400 BW= Coherence H0:PEM-BSC0_MAGX / H:LSC-AS_Q H0:PEM-BSC9_MAGX / H:LSC-AS_Q Coherence T0=08// :30:00 Avg=400 BW=0.0778

18 Level in AS_Q consistent with magnetic field coupling from PEM injections Traced to pulsed in-duct LVEA and VEA heating: Red: pulsed and staged heating on; Black: staged heating only Power spectrum Magnitude H0:PEM-LVEA_MAGY(REF48) H0:PEM-LVEA_MAGY(REF52) H0:PEM-LVEA_MAGY(REF54) H0:PEM-LVEA_MAGY(REF56) H0:PEM-LVEA_MAGY(REF58) H0:PEM-LVEA_MAGY *T0=06/03/ :45:30 Avg=6 BW=