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Ground vibration measurements

Ground vibration measurements. Heiko Ehrlichmann, Wilhelm Bialowons, DESY, Hamburg, Germany. Motivation. Comparison of „cultural noise“ impact at several accelerator laboratories with always the same seismic equipment -> Site comparison for future accelerators -> linear collider

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Ground vibration measurements

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  1. Ground vibration measurements Heiko Ehrlichmann, Wilhelm Bialowons, DESY, Hamburg, Germany

  2. Motivation • Comparison of „cultural noise“ impact at several accelerator laboratories with always the same seismic equipment • -> Site comparison for future accelerators -> linear collider (TESLA or GLC) -> synchrotron light source (PETRA III ….)

  3. Equipment • Broadband seismometers GÜRALP CMG-3T three components: vertical, 2x horizontal frequency range: 120s(360s) – 100Hz integrated 24bit ADC, 200Hz sampling rate output signal: velocity data acquisition via notebook • Geophone system KEBE, SENSOR SM-6 separate sensors for vertical or horizontal frequency range: 3Hz – 250Hz nonlinear high gain amplifier 16bit USB-ADC, 500Hz sampling output signal: velocity data acquisition via notebook

  4. GÜRALP seismometer two of our sensors at DESY

  5. Geophon system two geophones on the street

  6. Application • Seismometer -> precision measurement • continuous data taking for long periods -> one week and more, 24h at least • one dataset every minute • -> 5GB raw data per week • Geophone -> short „snapshots“ • data taking for some minutes

  7. Data analysis (standard, automated) • one dataset per minute • FFT based on this file structure -> 1/60Hz lower frequency limit • integration (velocity -> motion) • -> power spectral density (PSD) of motion • integration above cut frequency -> rms-value of motion (in nm) • interactive Visual Basic programs • focus on: vertical component

  8. Typical PSD (interactive display) synchronous measurement in the HERA tunnel (red) and on ground level direct above (black), 15min average • 1/w4 drop • microseismic peak (seven second hum) at 0.1-0.2Hz • cultural noise above 1Hz coherence PSD (mm2/Hz)

  9. Integrated view -> rms vs fcut rms f>1Hz: inside the tunnel: 48nm at ground level: 53nm synchronous measurement in the HERA tunnel (red) and on ground level direct above (black), 15min average

  10. Cultural noise caused by the sum of • traffic on streets • railways • urban installations • transformers • heavy machines • industry

  11. Comparison:ASSE(salt mine) - DESY rms f<1Hz: DESY, in HERA: 40nm Asse, 900m deep: 1nm -> clear signal of cultural noise above 1Hz at DESY DESY Salt mine ASSE HERA tunnel at WL745m (red) and salt mine ASSE, depth: 900m (light red), 15min average at midnight

  12. Example for traffic <- raw data, 1min ->Truck passing HERA tunnel at NL605m (red) and salt mine ASSE, depth: 900m (light red)

  13. Modelling of cultural noise in Cooperation of DESY and TUHH (Technical University of Hamburg) Comparison of calculated PSD’s for different truck velocities and one measured PSD

  14. rms (f>1Hz)versus time rms value of vertical motion (nm),HERA tunnel at WL745m, calendar week 13

  15. accelerator laboratories: DESY CERN ESRF SLAC FNAL APS KEK SPring8 reference places Seismic station Moxa Salt mine ASSE DESY Zeuthen Hamburg downtown … Data taken at:

  16. ASSE: ground level and depth of 900m rms PSD rms f<1Hz: Ground level: 5nm 900m deep: 1nm ground level 900m deep

  17. CERN P4: ground level and LHC tunnel rms PSD rms f<1Hz: Hall at P4, ground level: 6nm LHC tunnel at P4: 2nm hall LHC tunnel

  18. CERN LHC tunnel: P8 and P4 rms PSD rms f<1Hz: LHC tunnel at P8: 2nm LHC tunnel at P4: 1nm P8, near Geneva P4

  19. SLAC: sector 10 and copper mountains rms PSD rms f<1Hz: sector 10: 6nm copper mountain: 2nm sector 10 copper mountain

  20. preliminary: KEK ATF rms PSD rms f<1Hz: Outside the radiation shielding: 86nm Close to the extraction line: 76nm outside shielding at extraction line

  21. Site comparison (PSD)

  22. Site comparison (integral view)

  23. Site comparison (rms f>1Hz)

  24. Free access to our data ! • All our data are „freeware“ -> http://desyntwww.desy.de/~seismo/Seismometer/ -> linked via DESYmachine status webpage -> special webpage coming soon

  25. acknowledgements the measurements were done with the help of: • Louis Emery from APS • Ralph Assmann, Williame Coosemans, Andreas Herty and Stefano Redaelli from CERN • Carsten Kluth from DESY • Lin Zhang from ESRF • Kai Desler, David Finley, Victor Kuchler from FNAL • Karl-Heinz Jäckel from GFZ Potsdam • Volker Behrens and Hui Fricke from GSF • Thomas Jahr, Matthias Meininger and Wernfrid Kühnel from University of Jena • Toshiaki Tauchi from KEK • Jerry Aarons, Fred Asiri, Frederic Le Pimpec, Marc Ross, Andrei Seryi and Javier Sevilla from SLAC • Sakuo Matsui andTsumoru Shintake from SPring8 • Thorsten Bierer and Jürgen Grabe from TUHH

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