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 (TESLA or GLC) -> synchrotron light source (PETRA III ….)

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

GÜRALP seismometer two of our sensors at DESY

Geophon system two geophones on the street

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

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

Typical PSD (interactive display) 1 /  4  drop microseismic peak (seven second hum) at Hz cultural noise above 1Hz synchronous measurement in the HERA tunnel (red) and on ground level direct above (black), 15min average coherence PSD (  m 2 /Hz)

Integrated view -> rms vs f cut 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

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

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 HERA tunnel at WL745m (red) and salt mine ASSE, depth: 900m (light red), 15min average at midnight DESY Salt mine ASSE

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

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

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

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

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

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

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

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

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

Site comparison (PSD)

Site comparison (integral view)

Site comparison (rms f>1Hz) locationminimum rms (nm)additional rms (nm) on weekdays Moxa Asse (depth: 900m) DESY and more DESY HERA tunnel and more Ellerhoop CERN5+ 10 CERN LHC tunnel2+ 2 ESRF and more SLAC5+ 5 Copper Mountain< 2 FNAL7+ 3 FNAL Numi3+ 3 APS15+ 2

Free access to our data ! All our data are „freeware“ -> -> linked via DESY machine status webpage -> special webpage coming soon

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 and Tsumoru Shintake from SPring8 Thorsten Bierer and Jürgen Grabe from TUHH