ground vibration measurements
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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-
3Tthree components: vertical, 2x horizontalfrequency range: 120s(360s) – 100Hzintegrated 24bit ADC, 200Hz sampling rateoutput signal: velocitydata acquisition via notebook
• Geophone system KEBE, SENSOR SM-6separate sensors for vertical or horizontal frequency range: 3Hz – 250Hznonlinear high gain amplifier16bit USB-ADC, 500Hz samplingoutput signal: velocitydata 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 0.1-0.2Hz
• cultural noiseabove 1Hz
synchronous measurement in the HERA tunnel (red) and on ground level direct above (black), 15min average
coherence
PSD (m2/Hz)
Integrated view -> rms vs fcut
rms f>1Hz:inside the tunnel:
48nmat 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:
40nmAsse, 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-value of vertical motion (nm), HERA tunnel at WL745m, calender week 13
0
20
40
60
80
100
120
140
160
180
200
82 83 84 85 86 87 88 89
time (d)
rms (f>1Hz) versus timerms 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: 5nm900m deep: 1nm
rms
ground level
900m deep
PSD
CERN P4: ground level and LHC tunnel
rms f<1Hz:Hall at P4, ground level: 6nmLHC tunnel at P4: 2nm
rmsPSD
LHC tunnel
hall
CERN LHC tunnel: P8 and P4
rms f<1Hz:LHC tunnel at P8: 2nmLHC tunnel at P4: 1nm
rmsPSD
P4
P8, near Geneva
SLAC: sector 10 and copper mountains
rms f<1Hz:sector 10: 6nmcopper mountain: 2nm
rmsPSD
copper mountain
sector 10
preliminary: KEK ATF
rms f<1Hz:Outside the radiation shielding: 86nmClose to the extraction line: 76nm
rmsPSD
at extraction line
outside shielding
Site comparison (PSD)
Site comparison (integral view)
Site comparison (rms f>1Hz)location minimum rms
(nm) additional rms (nm) on
weekdays
Moxa 0.6 + 0.5
Asse (depth: 900m) 0.8 + 0.5
DESY 40 + 100 and more
DESY HERA tunnel 40 + 80 and more
Ellerhoop 15 + 35
CERN 5 + 10
CERN LHC tunnel 2 + 2
ESRF 40 +120 and more
SLAC 5 + 5
Copper Mountain < 2
FNAL 7 + 3
FNAL Numi 3 + 3
APS 15 + 2
Free access to our data !• All our data are „freeware“
-> http://desyntwww.desy.de/~seismo/Seismometer/-> linked via DESY machine status webpage-> special webpage coming soon
acknowledgementsthe 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