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 (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