MiniGrail

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MiniGrail
Location(s)Netherlands OOjs UI icon edit-ltr-progressive.svg
Organization Leiden University   OOjs UI icon edit-ltr-progressive.svg
Telescope style gravitational-wave observatory   OOjs UI icon edit-ltr-progressive.svg
Website www.minigrail.nl OOjs UI icon edit-ltr-progressive.svg
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MiniGRAIL was a type of Resonant Mass Antenna, [1] which is a massive sphere that used to detect gravitational waves. The MiniGRAIL was the first such detector to use a spherical design. It is located at Leiden University in the Netherlands. The project was managed by the Kamerlingh Onnes Laboratory. [2] A team from the Department of Theoretical Physics of the University of Geneva, Switzerland, was also heavily involved. The project was terminated in 2005.

Contents

Gravitational waves are a type of radiation that is emitted by objects that have mass and are undergoing acceleration. The strongest sources of gravitational waves are suspected to be compact objects such as neutron stars and black holes. This detector may be able to detect certain types of instabilities in rotating single and binary neutron stars, and the merger of small black holes or neutron stars. [3]

Design

A spherical design has the benefit of being able to detect gravitational waves arriving from any direction, and it is sensitive to polarization. [4] When gravitation waves with frequencies around 3,000 Hz pass through the MiniGRAIL ball, it will vibrate with displacements on the order of 10−20 m. [5] For comparison, the cross-section of a single proton (the nucleus of a hydrogen atom), is 10−15 m (1 fm). [6]

To improve sensitivity, the detector was intended to operate at a temperature of 20 mK. [2] The original antenna for the MiniGRAIL detector was a 68 cm diameter sphere made of an alloy of copper with 6% aluminium. This sphere had a mass of 1,150 kg and resonated at a frequency of 3,250 Hz. It was isolated from vibration by seven 140 kg masses. The bandwidth of the detector was expected to be ±230 Hz. [3]

During the casting of the sphere, a crack appeared that reduced the quality to unacceptable levels. It was replaced by a 68 cm sphere with a mass of 1,300 kg. This was manufactured by ItalBronze in Brazil. The larger mass lowered the resonant frequencies by about 200 Hz. [7] The sphere is suspended from stainless steel cables to which springs and masses are attached to dampen vibrations. Cooling is accomplished using a dilution refrigerator. [8]

Tests at temperatures of 5 K showed that the detector had a peak strain sensitivity of 1.5 × 10−20 Hz−1⁄2 at a frequency of 2942.9 Hz. Over a bandwidth of 30 Hz, the strain sensitivity was more than 5 × 10−20 Hz−1⁄2. This sensitivity is expected to improve by an order of magnitude when the instrument is operating at 50 mK. [4]

A similar detector named "Mario Schenberg" is located in São Paulo. The co-operation of the detectors strongly increase the chances of detection by looking at coincidences. [9]

Related Research Articles

In theories of quantum gravity, the graviton is the hypothetical quantum of gravity, an elementary particle that mediates the force of gravitational interaction. There is no complete quantum field theory of gravitons due to an outstanding mathematical problem with renormalization in general relativity. In string theory, believed by some to be a consistent theory of quantum gravity, the graviton is a massless state of a fundamental string.

<span class="mw-page-title-main">LIGO</span> Gravitational wave detector

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory designed to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. Two large observatories were built in the United States with the aim of detecting gravitational waves by laser interferometry. These observatories use mirrors spaced four kilometers apart which are capable of detecting a change of less than one ten-thousandth the charge diameter of a proton.

<span class="mw-page-title-main">Laser Interferometer Space Antenna</span> European space mission to measure gravitational waves

The Laser Interferometer Space Antenna (LISA) is a proposed space probe to detect and accurately measure gravitational waves—tiny ripples in the fabric of spacetime—from astronomical sources. LISA would be the first dedicated space-based gravitational-wave observatory. It aims to measure gravitational waves directly by using laser interferometry. The LISA concept has a constellation of three spacecraft arranged in an equilateral triangle with sides 2.5 million kilometres long, flying along an Earth-like heliocentric orbit. The distance between the satellites is precisely monitored to detect a passing gravitational wave.

<span class="mw-page-title-main">Gravitational collapse</span> Contraction of an astronomical object due to the influence of its gravity

Gravitational collapse is the contraction of an astronomical object due to the influence of its own gravity, which tends to draw matter inward toward the center of gravity. Gravitational collapse is a fundamental mechanism for structure formation in the universe. Over time an initial, relatively smooth distribution of matter will collapse to form pockets of higher density, typically creating a hierarchy of condensed structures such as clusters of galaxies, stellar groups, stars and planets.

<span class="mw-page-title-main">Millisecond pulsar</span> Pulsar with a rotational period less than about 10 milliseconds

A millisecond pulsar (MSP) is a pulsar with a rotational period less than about 10 milliseconds. Millisecond pulsars have been detected in radio, X-ray, and gamma ray portions of the electromagnetic spectrum. The leading theory for the origin of millisecond pulsars is that they are old, rapidly rotating neutron stars that have been spun up or "recycled" through accretion of matter from a companion star in a close binary system. For this reason, millisecond pulsars are sometimes called recycled pulsars.

The Schrödinger–Newton equation, sometimes referred to as the Newton–Schrödinger or Schrödinger–Poisson equation, is a nonlinear modification of the Schrödinger equation with a Newtonian gravitational potential, where the gravitational potential emerges from the treatment of the wave function as a mass density, including a term that represents interaction of a particle with its own gravitational field. The inclusion of a self-interaction term represents a fundamental alteration of quantum mechanics. It can be written either as a single integro-differential equation or as a coupled system of a Schrödinger and a Poisson equation. In the latter case it is also referred to in the plural form.

<span class="mw-page-title-main">GEO600</span> Gravitational wave detector in Germany

GEO600 is a gravitational wave detector located near Sarstedt, a town 20 km to the south of Hanover, Germany. It is designed and operated by scientists from the Max Planck Institute for Gravitational Physics, Max Planck Institute of Quantum Optics and the Leibniz Universität Hannover, along with University of Glasgow, University of Birmingham and Cardiff University in the United Kingdom, and is funded by the Max Planck Society and the Science and Technology Facilities Council (STFC). GEO600 is capable of detecting gravitational waves in the frequency range 50 Hz to 1.5 kHz, and is part of a worldwide network of gravitational wave detectors. This instrument, and its sister interferometric detectors, when operational, are some of the most sensitive gravitational wave detectors ever designed. They are designed to detect relative changes in distance of the order of 10−21, about the size of a single atom compared to the distance from the Sun to the Earth. Construction on the project began in 1995.

<span class="mw-page-title-main">Virgo interferometer</span> Gravitational wave detector in Santo Stefano a Macerata, Tuscany, Italy

The Virgo interferometer is a large Michelson interferometer designed to detect gravitational waves predicted by general relativity. It is located in Santo Stefano a Macerata, near the city of Pisa, Italy. The instrument's two arms are three kilometres long, housing its mirrors and instrumentation inside an ultra-high vacuum.

<span class="mw-page-title-main">Gravitational wave</span> Propagating spacetime ripple

Gravitational waves are waves of the intensity of gravity that are generated by the accelerated masses of binary stars and other motions of gravitating masses, and propagate as waves outward from their source at the speed of light. They were first proposed by Oliver Heaviside in 1893 and then later by Henri Poincaré in 1905 as the gravitational equivalent of electromagnetic waves.

<span class="mw-page-title-main">Gravitational-wave observatory</span> Device used to measure gravitational waves

A gravitational-wave detector is any device designed to measure tiny distortions of spacetime called gravitational waves. Since the 1960s, various kinds of gravitational-wave detectors have been built and constantly improved. The present-day generation of laser interferometers has reached the necessary sensitivity to detect gravitational waves from astronomical sources, thus forming the primary tool of gravitational-wave astronomy.

<span class="mw-page-title-main">Gravitational-wave astronomy</span> Branch of astronomy using gravitational waves

Gravitational-wave astronomy is an emerging field of science, concerning the observations of gravitational waves to collect relatively unique data and make inferences about objects such as neutron stars and black holes, events such as supernovae, and processes including those of the early universe shortly after the Big Bang.

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) is a consortium of astronomers who share a common goal of detecting gravitational waves via regular observations of an ensemble of millisecond pulsars using the Green Bank Telescope, Arecibo Observatory, and the Very Large Array. This project is being carried out in collaboration with international partners in the Parkes Pulsar Timing Array in Australia, the European Pulsar Timing Array, and the Indian Pulsar Timing Array as part of the International Pulsar Timing Array.

Allegro was a ground-based, cryogenic resonant Weber bar, gravitational-wave detector run by Warren Johnson, et al. at Louisiana State University in Baton Rouge, Louisiana. The detector was commissioned in the early 1990s, and was decommissioned in 2008.

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<span class="mw-page-title-main">Extreme mass ratio inspiral</span>

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<span class="mw-page-title-main">Jean-Paul Richard</span> Canadian physicist

Jean-Paul Richard was a Canadian physicist, academic and researcher. He was a Professor of Physics at the University of Maryland.

Lisa Barsotti is a research scientist at the Massachusetts Institute of Technology Kavli Institute.

References

  1. ↑ Schutz , Bernard (2009-05-14). A First Course in General Relativity (2nd ed.). Cambridge. pp.  214–220. ISBN   978-0521887052.
  2. 1 2 de Waard, A; et al. (2003). "MiniGRAIL, the first spherical detector". Classical and Quantum Gravity. 20 (10): S143–S151. Bibcode:2003CQGra..20S.143D. doi:10.1088/0264-9381/20/10/317. S2CID   250902916.
  3. 1 2 Van Houwelingen, Jeroen (2002-06-24). "Development of a superconducting thin-film Nb-coil for use in the MiniGRAIL transducers" (PDF). Leiden University. pp. 1–17. Retrieved 2009-09-16.
  4. 1 2 Gottardi, L.; De Waard, A.; Usenko, O.; Frossati, G.; Podt, M.; Flokstra, J.; Bassan, M.; Fafone, V.; et al. (November 2007). "Sensitivity of the spherical gravitational wave detector MiniGRAIL operating at 5K". Physical Review D. 76 (10): 102005.1–102005.10. arXiv: 0705.0122 . Bibcode:2007PhRvD..76j2005G. doi:10.1103/PhysRevD.76.102005. S2CID   119261963.
  5. ↑ Bruins, Eppo (2004-11-26). "Listen, two black holes are clashing!". innovations-report. Retrieved 2009-09-16.
  6. ↑ Ford, Kenneth William (2005). The quantum world: quantum physics for everyone. Harvard University Press. p.  11. ISBN   0-674-01832-X.
  7. ↑ de Waard, A.; et al. (2005). "MiniGRAIL progress report 2004". Classical and Quantum Gravity. 22 (10): S215–S219. Bibcode:2005CQGra..22S.215D. doi:10.1088/0264-9381/22/10/012. S2CID   35852172.
  8. ↑ de Waard, A.; et al. (March 2004). "Cooling down MiniGRAIL to milli-Kelvin temperatures" (PDF). Classical and Quantum Gravity. 21 (5): S465–S471. Bibcode:2004CQGra..21S.465D. doi:10.1088/0264-9381/21/5/012. S2CID   250811527.
  9. ↑ Frajuca, Carlos; et al. (December 2005). "Resonant transducers for spherical gravitational wave detectors" (PDF). Brazilian Journal of Physics. 35 (4b): 1201–1203. Bibcode:2005BrJPh..35.1201F. doi: 10.1590/S0103-97332005000700050 .

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