Introduction
GEO600 – Gravitational Wave Detector (German-British)
Max-Planck-Institut für Gravitationsphysik - Hannover, Germany
Website
History - In the 1970's, two European groups initiated investigations into laser-interferometric gravitational wave (GW) detection. In 1975 the Max Planck Institute for Astrophysics in Munich started with a prototype of 3 m armlength, which later (1983), at the Max Planck Institute of Quantum Optics (MPQ) in Garching, led to a prototype with 30 m armlength. In 1977 the Department of Physics and Astronomy of the University of Glasgow began similar investigations, and in 1980 started operation of a 10 m prototype. In 1985 the Garching group proposed the construction of a large detector with 3 km armlength, the British group an equivalent project in 1986. The two groups combined their efforts in 1989 - the project GEO was born, with the Harz mountains (Northern Germany) considered an ideal site. The project was, however, not funded, because of financial problems. Thus in 1994 a smaller detector was proposed: GEO600, to be built in the lowlands near Hannover, with arms of 600 m in length. The construction of this British-German GW detector started in September 1995. In 2001 the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI) in Potsdam took over the Hannover branch of the MPQ, and since 2002 the detector is operated by a joint Center of Gravitational Physics of AEI and Leibniz Universität Hannover, together with the universities of Glasgow and Cardiff. Between 2002 and 2006 GEO600 participated in several data runs in coincidence with the LIGO detectors and is now gradually approaching design sensitivity.
Worldwide Network - Reliable detection of gravitational waves requires the operation of at least two detectors in coincidence – if the signals coincide with those of a distant detector, local perturbations can be ruled out. In order to obtain the full information about the gravitational waves (source position, polarization), data from at least four detectors have to be compared. Thus, the GEO600 team collaborates with the GW groups in the USA (LIGO), in France/Italy (VIRGO) and in Japan (TAMA). As a member of the LIGO Scientific Collaboration (LSC) GEO600 has performed several long-term data runs together with the LIGO detectors.
Aims - Gravitational wave astronomy provides a totally new look at the Universe. Gravitational waves give information on supernovae, black holes, compact binaries and the cosmic background radiation that cannot be obtained by other means. Furthermore, observation of binary systems allows to determine absolute distances and thus an accurate value of the Hubble constant.
Funding - Financial support of the GEO project has been supplied by the State of Lower Saxony, the Max Planck Society, the Particle Physics and Astronomy Research Council (UK), the Volkswagen Foundation, and the Federal Republic of Germany. Personnel costs are supplied by the Max Planck Society and the Leibniz University Hannover, running costs by the Max Planck Society.
 |
Image Above: GEO600 Facility – In the bottom left corner the central building for the laser and the vacuum tanks can be seen. The tubes, 600 m in length, run in covered trenches at the edge of the field upwards and to the right. Buildings for the mirrors are situated at the end of each tube.
(Credit: Albert Einstein Institute Hannover.) |
 |
| Bird's-eye view: The Gravitational Wave Detector "GEO600" in Ruthe near Hannover, Germany. In the front the central building for the laser and the vacuum tanks can be seen. The tubes, 600 m in length, run in covered trenches at the edge of the field upwards and to the right. Buildings for the mirrors are situated at the end of each tube. (Credit: Albert Einstein Institute Hannover.) |
Technical Principles
Here you will find technical details concerning the GEO600 Project,
with links to the Max-Planck-Institut für Gravitationsphysik Website.
Armlength, orientation, tube diameter, laser type, laser power, power recycling, optics, signal recycling, frequency range, bandwidth, sensitivity. [read more]
The Sensitivity of GEO600
The sensitivity of GEO600 depends on the bandwidth which in its turn depends on the signal recycling factor. The signal recycling of GEO600 thus provides the opportunity to change the spectral characteristics of the detector response especially those due to the shot noise limitations. [read more]
![The Optical Layout of GEO600]( "The technical drawing shows the optical layout of GEO600.")
The Optical Layout of GEO600
The small green arrows indicate beam waists. The greenish rectangles inside the tanks close to the walls are support platforms for the vibration isolation stacks. They restrict the area where the optical components can be placed. The large blue boxes represent the optical tables. Optical components are coloured in a light blue with black borders exept of those which (partially) reflect light, which are drawn in a darker shade of blue. The thickness of the beams is drawn according to their real diameter, whereas the colour of the beams indicate the intensity: the stronger the red of the beam the higher the intensity. [read more]
![The Cleanrooms of GEO600]( "The Cleanrooms of GEO600")
The Cleanrooms of GEO600
The handling of high quality optics requires cleanroom facilities to prevent even microscopic dust particles from entering the system. These dust particles would eventually be attached to the mirror surface and burnt into by the intense laser radiation of about 3 kW/cm2. As the handling of the high quality optics naturally takes place in the vicinity of and even in the tanks at least the surroundings of the tanks have to be of cleanroom quality. We hope to achieve a class <100 cleanroom (during the time a tank is opened) with the help of mobile plastic tents forming a laminar-flow box, large enough to enclose the tank and one or two people working with the optics. [read more]
![The Vacuum System of GEO600]( "This schematic diagram shows the vacuum system of GEO600. (Drawing by Kasem Mossavi)")
The Vacuum System of GEO600
The vacuum tubes for GEO600 have been manufactured and welded by the Hans Skodock GmbH in Hannover. The basic unit consists of 0.75 m long corrugated pieces of stainless steel with 60 cm diameter, 0.9 mm thickness, and a mass of about 20 kg. Six pieces each are welded at the supplier. After cleaning, these 3 m tubes have been joint together at the site by means of an orbital welding machine. The tubes are suspended at thin steel cables within a trench. The suspension consists of rotating disks mounted on a rail. So the tube can be rotated during welding and pushed into the trench afterwards. [read more]
![Baffle Positions]( "Baffle Positions")
Baffle Positions
The baffles we will use for GEO600 will consist of a conical part (blue in the picture) and a cylindrical part (light green) forming an angle of 25.7 degrees. The total width of a baffle is 14 cm, giving a height of about 3 cm. The surfaces of the baffle will be blackened with an commercial oxidizing stuff called Ebonol (from the japanese company: Enthone-Imasa, German representative: Enthone-Imasa Germany, 40699 Erkrath, Niermannsweg 3-5) to give sufficiently low back-scatter and reflection. The backscatter measured is about 0.1 -1% /sterad depending on the surface roughness of the stainless steel. A direct reflex is not detectable. The multiple reflections at the baffles' blackened surfaces, necessary for the light to return to the mirror will thus sufficiently reduce it's amplitude. [read more]
We did some measurements of the seismic motion at the GEO600 site in Ruthe. Most of the measurements were performed in the east end-building at the inner part of the split foundation. We used two accelerometers (Bruel&Kjær big ones) and the corresponding amplifiers (Roland Schilling design). For the measurements below 10 Hz we used additional amplifiers with a gain of 100 to increase the signal above the spectrum analyzer's input noise. By M. Pickenpack and B. Willke. [read more]
![Seismic Noise]( "Click to view full-size image")
Seismic Noise
Horizontal microseismic noise on the inner part of the split foundation in the E end building at Ruthe, produced by a person, a car, seismic background and electric noise. By David I. Robertson. [read more]
Triple Pendulum Suspension
Calum I. Torrie. [read more]
Here you find programs and tools that can be downloaded from this server as well as some outside links. By Andreas Freise. [read more]
FINESSE (Frequency domain INterfErometer Simulation Sotfware). [go to site]
Gravitational wave detector in Hannover tests holographic Universe — Can GEO600 hear the quantum noise of spacetime?
![Gravitational wave detector in Hannover tests holographic Universe — Can GEO600 hear the quantum noise of spacetime?]( "Gravitational wave detector in Hannover tests holographic Universe — Can GEO600 hear the quantum noise of spacetime?")
Gravitational wave detector in Hannover tests holographic Universe — Can GEO600 hear the quantum noise of spacetime?
Are we living in a holographic Universe? Are space and time grainy? Is there quantum noise in spacetime? American physicist Craig Hogan is convinced that he has found proof in the data of the German-British gravitational wave detector GEO600 – and that his ideas could explain mysterious noise in the detector data which has not been explained so far. New experiments in the coming months will yield more evidence about Craig Hogan’s assumptions:
To test the theory of holographic noise, the frequency of GEO600’s maximum sensitivity will be shifted towards ever higher frequencies. The frequency of maximum sensitivity is the tone that the detector can hear best. It is normally adjusted to offer the best chance for hearing exploding stars or merging black holes.
Even if it turns out that the mysterious noise is the same at high frequencies as at the lower ones, this will not constitute proof for Hogan’s hypothesis. It would, however, provide a strong motivation for further study. The sensitivity of GEO600 will then be significantly improved by using ‘squeezed vacuum’ and by the installation of a mode filter in a new vacuum chamber. The technology of ‘squeezed vacuum’ was particularly refined in Hannover and would be used in a gravitational wave detector for the first time.
“We are very eager to find out what we can learn about the possible holographic noise over the course of the coming year”, says Prof. Dr. Karsten Danzmann, director of the Hannover Albert-Einstein-Institute. “GEO600 is the only experiment in the world able to test this controversial theory at this time. Unlike the other large laser interferometers, GEO600 reacts particularly sensitively to lateral movement of the beam splitter because it is constructed using the principle of signal recycling. Normally this is inconvenient, but we need the signal recycling to compensate for the shorter arm lengths compared to other detectors. The holographic noise, however, produces exactly such a lateral signal and so the disadvantage becomes an advantage in this case. You could say that this has placed us in the very centre of a tornado in fundamental research!”
Click link below right for more information on the GEO600 Grav. Wave Detector »
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Introduction
GEO600 – Gravitational Wave Detector (German-British)
Max-Planck-Institut für Gravitationsphysik - Hannover, Germany
Website
History - In the 1970's, two European groups initiated investigations into laser-interferometric gravitational wave (GW) detection. In 1975 the Max Planck Institute for Astrophysics in Munich started with a prototype of 3 m armlength, which later (1983), at the Max Planck Institute of Quantum Optics (MPQ) in Garching, led to a prototype with 30 m armlength. In 1977 the Department of Physics and Astronomy of the University of Glasgow began similar investigations, and in 1980 started operation of a 10 m prototype. In 1985 the Garching group proposed the construction of a large detector with 3 km armlength, the British group an equivalent project in 1986. The two groups combined their efforts in 1989 - the project GEO was born, with the Harz mountains (Northern Germany) considered an ideal site. The project was, however, not funded, because of financial problems. Thus in 1994 a smaller detector was proposed: GEO600, to be built in the lowlands near Hannover, with arms of 600 m in length. The construction of this British-German GW detector started in September 1995. In 2001 the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI) in Potsdam took over the Hannover branch of the MPQ, and since 2002 the detector is operated by a joint Center of Gravitational Physics of AEI and Leibniz Universität Hannover, together with the universities of Glasgow and Cardiff. Between 2002 and 2006 GEO600 participated in several data runs in coincidence with the LIGO detectors and is now gradually approaching design sensitivity.
Worldwide Network - Reliable detection of gravitational waves requires the operation of at least two detectors in coincidence – if the signals coincide with those of a distant detector, local perturbations can be ruled out. In order to obtain the full information about the gravitational waves (source position, polarization), data from at least four detectors have to be compared. Thus, the GEO600 team collaborates with the GW groups in the USA (LIGO), in France/Italy (VIRGO) and in Japan (TAMA). As a member of the LIGO Scientific Collaboration (LSC) GEO600 has performed several long-term data runs together with the LIGO detectors.
Aims - Gravitational wave astronomy provides a totally new look at the Universe. Gravitational waves give information on supernovae, black holes, compact binaries and the cosmic background radiation that cannot be obtained by other means. Furthermore, observation of binary systems allows to determine absolute distances and thus an accurate value of the Hubble constant.
Funding - Financial support of the GEO project has been supplied by the State of Lower Saxony, the Max Planck Society, the Particle Physics and Astronomy Research Council (UK), the Volkswagen Foundation, and the Federal Republic of Germany. Personnel costs are supplied by the Max Planck Society and the Leibniz University Hannover, running costs by the Max Planck Society.
|
Image Above: GEO600 Facility – In the bottom left corner the central building for the laser and the vacuum tanks can be seen. The tubes, 600 m in length, run in covered trenches at the edge of the field upwards and to the right. Buildings for the mirrors are situated at the end of each tube.
(Credit: Albert Einstein Institute Hannover.) |
|
| Bird's-eye view: The Gravitational Wave Detector "GEO600" in Ruthe near Hannover, Germany. In the front the central building for the laser and the vacuum tanks can be seen. The tubes, 600 m in length, run in covered trenches at the edge of the field upwards and to the right. Buildings for the mirrors are situated at the end of each tube. (Credit: Albert Einstein Institute Hannover.) |
Technical Principles
Here you will find technical details concerning the GEO600 Project,
with links to the Max-Planck-Institut für Gravitationsphysik Website.
Armlength, orientation, tube diameter, laser type, laser power, power recycling, optics, signal recycling, frequency range, bandwidth, sensitivity. [read more]
The Sensitivity of GEO600
The sensitivity of GEO600 depends on the bandwidth which in its turn depends on the signal recycling factor. The signal recycling of GEO600 thus provides the opportunity to change the spectral characteristics of the detector response especially those due to the shot noise limitations. [read more]
![The Optical Layout of GEO600]( "The technical drawing shows the optical layout of GEO600.")
The Optical Layout of GEO600
The small green arrows indicate beam waists. The greenish rectangles inside the tanks close to the walls are support platforms for the vibration isolation stacks. They restrict the area where the optical components can be placed. The large blue boxes represent the optical tables. Optical components are coloured in a light blue with black borders exept of those which (partially) reflect light, which are drawn in a darker shade of blue. The thickness of the beams is drawn according to their real diameter, whereas the colour of the beams indicate the intensity: the stronger the red of the beam the higher the intensity. [read more]
![The Cleanrooms of GEO600]( "The Cleanrooms of GEO600")
The Cleanrooms of GEO600
The handling of high quality optics requires cleanroom facilities to prevent even microscopic dust particles from entering the system. These dust particles would eventually be attached to the mirror surface and burnt into by the intense laser radiation of about 3 kW/cm2. As the handling of the high quality optics naturally takes place in the vicinity of and even in the tanks at least the surroundings of the tanks have to be of cleanroom quality. We hope to achieve a class <100 cleanroom (during the time a tank is opened) with the help of mobile plastic tents forming a laminar-flow box, large enough to enclose the tank and one or two people working with the optics. [read more]
![The Vacuum System of GEO600]( "This schematic diagram shows the vacuum system of GEO600. (Drawing by Kasem Mossavi)")
The Vacuum System of GEO600
The vacuum tubes for GEO600 have been manufactured and welded by the Hans Skodock GmbH in Hannover. The basic unit consists of 0.75 m long corrugated pieces of stainless steel with 60 cm diameter, 0.9 mm thickness, and a mass of about 20 kg. Six pieces each are welded at the supplier. After cleaning, these 3 m tubes have been joint together at the site by means of an orbital welding machine. The tubes are suspended at thin steel cables within a trench. The suspension consists of rotating disks mounted on a rail. So the tube can be rotated during welding and pushed into the trench afterwards. [read more]
![Baffle Positions]( "Baffle Positions")
Baffle Positions
The baffles we will use for GEO600 will consist of a conical part (blue in the picture) and a cylindrical part (light green) forming an angle of 25.7 degrees. The total width of a baffle is 14 cm, giving a height of about 3 cm. The surfaces of the baffle will be blackened with an commercial oxidizing stuff called Ebonol (from the japanese company: Enthone-Imasa, German representative: Enthone-Imasa Germany, 40699 Erkrath, Niermannsweg 3-5) to give sufficiently low back-scatter and reflection. The backscatter measured is about 0.1 -1% /sterad depending on the surface roughness of the stainless steel. A direct reflex is not detectable. The multiple reflections at the baffles' blackened surfaces, necessary for the light to return to the mirror will thus sufficiently reduce it's amplitude. [read more]
We did some measurements of the seismic motion at the GEO600 site in Ruthe. Most of the measurements were performed in the east end-building at the inner part of the split foundation. We used two accelerometers (Bruel&Kjær big ones) and the corresponding amplifiers (Roland Schilling design). For the measurements below 10 Hz we used additional amplifiers with a gain of 100 to increase the signal above the spectrum analyzer's input noise. By M. Pickenpack and B. Willke. [read more]
![Seismic Noise]( "Click to view full-size image")
Seismic Noise
Horizontal microseismic noise on the inner part of the split foundation in the E end building at Ruthe, produced by a person, a car, seismic background and electric noise. By David I. Robertson. [read more]
Triple Pendulum Suspension
Calum I. Torrie. [read more]
Here you find programs and tools that can be downloaded from this server as well as some outside links. By Andreas Freise. [read more]
FINESSE (Frequency domain INterfErometer Simulation Sotfware). [go to site]
Gravitational wave detector in Hannover tests holographic Universe — Can GEO600 hear the quantum noise of spacetime?
![Gravitational wave detector in Hannover tests holographic Universe — Can GEO600 hear the quantum noise of spacetime?]( "Gravitational wave detector in Hannover tests holographic Universe — Can GEO600 hear the quantum noise of spacetime?")
Gravitational wave detector in Hannover tests holographic Universe — Can GEO600 hear the quantum noise of spacetime?
Are we living in a holographic Universe? Are space and time grainy? Is there quantum noise in spacetime? American physicist Craig Hogan is convinced that he has found proof in the data of the German-British gravitational wave detector GEO600 – and that his ideas could explain mysterious noise in the detector data which has not been explained so far. New experiments in the coming months will yield more evidence about Craig Hogan’s assumptions:
To test the theory of holographic noise, the frequency of GEO600’s maximum sensitivity will be shifted towards ever higher frequencies. The frequency of maximum sensitivity is the tone that the detector can hear best. It is normally adjusted to offer the best chance for hearing exploding stars or merging black holes.
Even if it turns out that the mysterious noise is the same at high frequencies as at the lower ones, this will not constitute proof for Hogan’s hypothesis. It would, however, provide a strong motivation for further study. The sensitivity of GEO600 will then be significantly improved by using ‘squeezed vacuum’ and by the installation of a mode filter in a new vacuum chamber. The technology of ‘squeezed vacuum’ was particularly refined in Hannover and would be used in a gravitational wave detector for the first time.
“We are very eager to find out what we can learn about the possible holographic noise over the course of the coming year”, says Prof. Dr. Karsten Danzmann, director of the Hannover Albert-Einstein-Institute. “GEO600 is the only experiment in the world able to test this controversial theory at this time. Unlike the other large laser interferometers, GEO600 reacts particularly sensitively to lateral movement of the beam splitter because it is constructed using the principle of signal recycling. Normally this is inconvenient, but we need the signal recycling to compensate for the shorter arm lengths compared to other detectors. The holographic noise, however, produces exactly such a lateral signal and so the disadvantage becomes an advantage in this case. You could say that this has placed us in the very centre of a tornado in fundamental research!”
Click link below right for more information on the GEO600 Grav. Wave Detector »
Are you absolutely sure you want to delete this article? This process cannot be undone and is permanent.
Yes, Delete This Article
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Yes, Remove This Article
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