the search for and registration of the superweak angular ground motions n.
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The search for and registration of the superweak angular ground motions. JINR: J. Budagov, M. Lyablin., G. Shirkov. CERN: J-Ch. Gayde, D. Mergelkuhl. Original direction of the reflected beam. QPR. Laser. Direction the reflected beam after tilt base. θ. ψ. Base.

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the search for and registration of the superweak angular ground motions
The search for and registration of the superweak angular ground motions

JINR: J. Budagov, M. Lyablin., G. Shirkov.

CERN: J-Ch. Gayde, D. Mergelkuhl

main principle use reflected laser beam from horizontal surface liquid

Original

direction of the reflected beam

QPR

Laser

Direction

the reflected beam

after tilt base

θ

ψ

Base

The surface of the liquid

in case of horizontal basis

Cuvette with a liquid

The surface of the liquid

with tilt base

Main principle : use reflected laser beam from horizontal surface liquid

The principle of construction of the registration device to measure the seismic slope of the Earth’s surface.

experimental set up

50 cm

QPr

SM

CF

L

О1

50 cm

О

Sensor S

C

О2

Experimental set-up
  • L-laser
  • QPr-quadrant photodiode
  • O,O1,O2- bases
  • SM-semitransparent mirror
  • C-calibration screw
  • CF- collimator with changeable focus
  • frequency internal of 10-4Hz÷1Hz
  • The achieved inclinometer angular precision is 5 10-9 rad
the inclinometer tests the angular component of the earth quake
The inclinometer testsThe angular component of the Earth quake
  • The Earth quake in Siberia on February 26, 2011
  • Average amplitude of quake in Siberia was 6.5 units
  • The distance to Geneva (on the Earth surface) was determined: L=6160km
  • Calculation time of Earth quake begin Tcalc=6h 21 min in Siberia (world time)
  • practically coincides with the published Tpub=6h 17min (world time)
  • Amplitude angular oscillations consisted 2 10-6rad
earth surface single oscillation
Earth surface single oscillation.
  • The observation of an earth surface “single inclination” effect
  • Amplitude consisted few μrad
earth surface oscillations of an industrial noise origin
Earth surface oscillations of an industrial noise origin

Industrial origin noise:

high activity of auto– traffic,

works in the neighboring (with our set-up) Lab room,

people movement close to detecting set-up etc.

calculation sigma value angular ground motion from industrial noise
Calculation sigma value angular ground motion from industrial noise

Amplitude consisted

in work period 0.3 μrad

Amplitude consisted

In dinner time 0.04 μrad

measurement deformation value concrete floor
Measurement deformation value concrete floor
  • Concrete floor inclination due to man presence in 3 meters distance
  • from the experimental set-up
  • Amplitude consisted 0.3μrad
the microseismic peak observation by ground angular motion
The microseismic peak observation by ground angular motion

The seismogram of an earth surface angular oscillation at the “microseismic peak” frequency

fourier analyses oscillation at the microseismic peak
Fourier analysesoscillation at the “microseismic peak”

Amplitude Earth surface oscillation at the “microseismic peak” frequency

consist 0.03μradwith frequency fd=0.13Hz

Inclinometer sensitivity estimate on the level of ≈5·10-9rad

the long experimental setups space location stability and an earth surface angular oscillations

Experimental Hall

Linear accelerator-collider

Line of horizon

θmp

θmp

The Earth surface fixed time picture:

surface deformation induced by the standing waves originated by the interference of “microseicmic peak”

The long experimental setups space location stability and an earth surface angular oscillations

The accelerator-collider positioning on the earth

surface deformed by the microseismic peak wave

Different accelerator parts are inclined relative to the ”basic” horizontal

line and consequently particle beams going through the focusing elements

leave them with some angular spread θmp relative to the nominal.

As a result it leads to random motion position focus es accelerators

If we can stabilize the angular movements of the accelerator with an accuracy of 10-9nrad we will be able to stabilize position its focuses to within 50 nm

conclusion
Conclusion

The ground motion was studied by the detection of an earth surface angular oscillation. Instrumentally method is based on the conceptually new design laser inclinometer using the reflecting surface liquid, as a space stable (horizontal) reference level. The achieved inclinometer measurement precision was experimentally proved to be ≈5·10-9 rad.

The achieved laser inclinometer sensitivity was proved by observation (in Geneva) of:

  • Ground 2µrad oscillation caused by the Siberian earth quake (6160 km);
  • Single 1÷2 µrad oscillation of origin to be studied;
  • Industrial origin noise of about 10-7rad amplitude;
  • Microseismic peak for the first time recognized as a ground ≈ 10-8rad angular oscillation at 0.13Hz frequency.

The last observed effect if properly “compensated” by adequate instrumental method could give significant colliders luminosity increase by reduction of beams intersection area to about 50µ level (an estimate) due to some suppression of the lateral focus effect.

The instrument of this sort may happen to be useful for modern high precision research equipment stabilization, for example, of large telescope to reach an extreme resolution with them.