Outline

 
I. Coupling Mechanisms and Environmental Sources
    a) Acoustic
    b) Seismic
    c) Magnetic
    d) RF

II. Sensor Locations

III. Sensor Calibrations

IV. PEM Injections to Survey Coupling

V. Exercises and Help Wanted
 
 

Observed Mechanisms
 

1) Clipping or vignetting modulated by acoustically excited optic supports (biggest problem)

2) Back scattering modulated by relative motion of table optics and interferometer (one bad beam dump on
    ISCT1 increased acoustic coupling by a factor of10)

3) Microphonic electronics

4) Acoustic excitation of position sensing photo diodes (seen at optical levers)

5) Doppler shift of laser frequency by relative motion of PSL table and MC (likely seen at H2)

6) Index of refraction modulation of air by sound pressure (seen in pre-mode cleaner)

Worst Coupling Locations for S3
 

H1:
   1) reflected port table (ISCT1)
   2) laser table (PSL1)

H2:
   1) dark port (ISCT10)
   2) reflected port (ISCT7)

L1:
   1) reflected port (ISCT1)

Main Sources

 electronics fans (above 100 Hz)
 PSL chillers (around 100 Hz)
 HVAC (below 100 Hz)
 building creeks and thumps (broad band)
 close vehicles (50 - 150 Hz)
 aircraft (props: 50 - 100 Hz)
 wind (broad band)

 acoustic mitigation update Mar. 04   acoustic mitigation update Feb. 04   acoustic mitigation Nov. 03   acoustic mitigation Aug. 03   acoustic mitigation April 03

 acoustic coupling april 03
 

Observed Mechanisms
 

 
1) Up through seismic isolation stacks

2) Motion of optical levers relative to optic

3) Motion of optical tables

4) Tilt (e.g. wind tilts building and slab - potential coupling through microseismic feed forward)

5) Motion of buildings relative to each other (microseismic peak, earth tides)
 

Motors (0 to 10% below 60 Hz, 60/2, 60/3, 60/4  - 2, 4, 6, 8 pole asynchronous motors)
Wind (0.5 - 15 Hz)
Trucks (2 - 10 Hz)
Aircraft (50 - 100 Hz)
Building creeks (thermal expansion) 1 - 900 Hz (seismic below 20 Hz)
Dewar glitches (thermal expansion) 16 Hz
Counter propagating ocean wave fields 0.07 - 0.3 Hz
Earthquakes (far: 0.03 - 0.1 Hz; near: 0.1 - 1 Hz)
Solar system (12 hour and longer period)

 List of Mechanical Resonances
 
 
 

 SR10 gravel trucks Mar. 04   seismic coupling Mar 03   nuke fans, hood fans, controller fans Aug. 02   wind, construction, vit plant Mar. 02   pen taps Aug. 01

 wind farm Aug. 02   compressors, stomps, tank fire   Truck traffic, ground propagation velocity, Q, anisotropy ratio  earthquakes and wind storms

Observed Mechanisms
 

1)  Electronics and cables (seen at PSL, cable trays, satellite modules)

2)  Magnets on test mass (appears to be the dominant mechanism, at least at LHO MY and EY)
 

Main Sources
 

building heaters
large motors
lights

RADIO FREQUENCY COUPLING

Observed Mechanisms
 

1) RF photodiodes and cabling to demod boards

2) Other electronics

Main Sources
 

interferometer
motors
lights
external transmissions

 rf coupling Mar. 03

SENSOR LOCATIONS
Or what is ACCX and where is ISCT9?

 

H0:PEM-BSC5_MIC: microphone on BSC5 (end test mass vacuum chamber, 2k interferometer);
_ACCX: accelerometer, X-arm axis;
_MAGY: magnetometer, Y-arm axis;
_SEISZ: seismometer, vertical axis
H0:PEM-COIL_MAGX: vault coil magnetometer (this is the one case where X is actually north-south);
H0:PEM-RADIO_LVEA: radio receiver tuned to laser modulation frequency
H0:PEM-RADIO_CS1: broad band radio receiver, antenna on roof
_V1: voltage divider on mains power, phase 1.

 LLO

 LHO corner station , LHO Mid-X ,  LHO End-X , LHO Mid-Y , LHO End-Y
 

A more simple diagram of LHO vacuum chambers (tables are located by the HAM of the same number; e.g. ISCT3 is beside HAM3):

 

SENSOR CALIBRATIONS (simplified)

PEM installation records, equipment lists and locations etc.:

LHO PEM link    LLO PEM link

Best web source of frequency response, model numbers, specific calibrations etc:

Doug Lormand's LLO PEM Web Page

This simplified table can be used when the tabulated error is acceptable.
 

SENSOR	CALCULATION	CALIBRATION FACTOR	RANGE	AMPLITUDE  ERROR*	PHASE ERROR
Seismometers (Guralp e.g. PEM-MX_SEISZ)	((1 m/s) / 800 V) * (4 V /65536 counts)/10	0.0076 um/s per ADC count	0.1 - 20 Hz	22%	25 deg.
Tilt meters	(100 mR/V) * (4 V / 65536 counts)	0.0061 uR per ADC count	0 - 0.5 Hz	21%	no spec.
Microphones	calibration through DAQ system using sound std.	3.16 x 10-5 Pascals per ADC count	15 - 900 Hz except  LVEA_MIC, 15 - 7000 Hz	30%	no spec.
Accelerometers	((10 m/s2) / 100 V) * (4 V / 65536 counts)	6.1 mm/s2 per ADC count	1 - 900 Hz	35%	no spec.
Magnetometers	((100mT/ 10V) / (100)) * (4V / 65536 counts)	6.10 pT per ADC count above 10 Hz 6100 pT per ADC count below 0.1 Hz	0 - 900 Hz	25%	60 deg.

*15% uncertainty range for adc's (variation obtained from a couple of actual calibrations) + maximum variation of instrument calibration (e.g. the most extreme factory calibration for an individual seismometer axis is 816 instead of 800 giving 2% for a total uncertainty of 17%). When the calibration is through the entire DAQ system, the 15% is, of course, not included. To this number, I have added a percentage to account for amplitude response variation over the given frequency range.
 

S3 PEM INJECTIONS

Every science run, environmental coupling to AS_Q is tested by "injecting" acoustic, seismic, magnetic and radio signals in the various buildings. More details are given  here. The time of each individual burst during the S3 injections, as well as the relevant channels, are given here:
 

 PDF: S3PEMinjections  RTF: S3PEMinjections.rtf

Some examples of PEM injection coupling plots from Emelie and Masahiro:

 
 Emelie and Masahiro's S3 Plots

Fun exercises with PEM
 

 

1) Can you see injections in dtt time series and in dtt spectra (a good place to start is Dec 3, 2003 2:55:01 to 2:57:01 UTC, you should see injections every 5 s)?

2) Design filters to make injections more visible in time series.

3) Use engineering drawings linked above to obtain
        a) coupling site
        b) source location
        c) propagation velocity

4) What is the flight path of the airplane that made it through all Burst Group cuts (732000716)  movie ?

Help wanted:

1) Characterize and help find the sources of acoustic glitches in S3 (how often, where (triangulate) etc.) Develop monitor for acoustic glitches (e.g. variation of glitchMon).

2) Characterize and help find the sources of seismic glitches in S3. Develop monitor.

3) Characterize and help find the sources of magnetic glitches in S3 (how often, wave form, site-wide?). Develop monitor.

4) Characterize and help find the sources of voltage monitor glitches in S3. Develop monitor for large site-wide voltage glitches (could be a fairly simple modification of glitchMon).

5) Characterize and help find the sources of RF glitches in S3. Develop monitor.

6) More radio

a) Permanent rather than temporary RADIO_LVEA

b) Install broad band radio receivers at LLO.

c) Install last two broad band receivers at LHO.

d) LHO 4k LVEA radio receiver

e) Informed choice of radio bands to monitor.

f) Develop better setup for PEM injections of radio bursts.

7) Lightning monitor (Szabi)

8) Code that uses time of arrival differences at different detectors to give source direction (Szabi).

9) Install Bartington magnetometer in vault (Szabi).

10) Study wind coupling (how much will PEPI help).

11) Dewar glitch monitor. Which dewars are glitching at LLO & LHO (Emelie)

12) LHO version of Doug L.'s web page giving sensor details and standard spectra.

13) Airplane detector