Allegro was a ground-based, cryogenic resonant Weber bar, gravitational-wave detector[1] 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.
Mechanical design
The resonant bar in Allegro is 2300 kg of aluminum, 3 meters in length. Suspended in a cryogenic vacuum tank at 4.2 Kelvin, the bar's natural resonant frequency (the lowest longitudinal mode) is near 904 Hz.
The strain on the bar is measured by coupling a second, much lighter, suspended mass to the main heavier mass as a mechanical transformer at the same resonant frequency. Therefore, small motions of the primary mass generate much larger motions in the smaller mass. The differential displacement of the two masses is recorded using an inductive transducer and amplifier (a SQUID).[2]
Collaboration with LIGO
Due its close proximity to the LIGO Livingston Detector (one in the array of three, large-scale, laser interferometric detectors), Allegro has partnered with the LIGO Scientific collaboration to produce several results during the fourth science run of LIGO.[3]
References
Mauceli, E.; et al. (July 1996). "The Allegro gravitational wave detector: Data acquisition and analysis". Physical Review D. 54 (2). arXiv:gr-qc/9609058. Bibcode:1996PhRvD..54.1264M. doi:10.1103/PhysRevD.54.1264.
McHugh, M.; et al. (2005). "Calibration of the ALLEGRO resonant detector". Class. Quantum Grav. 22 (18). Bibcode:2005CQGra..22S.965M. doi:10.1088/0264-9381/22/18/S10.
Abbott, B.; et al. (July 2007). "First cross-correlation analysis of interferometric and resonant-bar gravitational-wave data for stochastic backgrounds". Physical Review D. 76 (022001). arXiv:gr-qc/0703068. Bibcode:2007PhRvD..76b2001A. doi:10.1103/PhysRevD.76.022001.
vte
Gravitational-wave astronomy
Gravitational wave Gravitational-wave observatory
Detectors
Resonant mass
antennas
Active
NAUTILUS (IGEC) AURIGA (IGEC) MiniGRAIL Mario Schenberg
Past
EXPLORER (IGEC) ALLEGRO (IGEC) NIOBE (IGEC) Stanford gravitational wave detector ALTAIR GEOGRAV AGATA Weber bar
Proposed
Past proposals
GRAIL (downsized to MiniGRAIL) TIGA SFERA Graviton (downsized to Mario Schenberg)
Ground-based
Interferometers
Active
AIGO (ACIGA) CLIO Fermilab holometer GEO600 Advanced LIGO (LIGO Scientific Collaboration) KAGRA Advanced Virgo (European Gravitational Observatory)
Past
TAMA 300 TAMA 20, later known as LISM TENKO-100 Caltech 40m interferometer
Planned
INDIGO (LIGO-India)
Proposed
Cosmic Explorer Einstein Telescope
Past proposals
AIGO (LIGO-Australia)
Space-based
interferometers
Planned
LISA
Proposed
Big Bang Observer DECIGO TianQin
Pulsar timing arrays
EPTA IPTA NANOGrav PPTA
Data analysis
Einstein@Home PyCBC Zooniverse: Gravity Spy
Observations
Events
List of observations First observation (GW150914) GW151012 GW151226 GW170104 GW170608 GW170729 GW170809 GW170814 GW170817 (first neutron star merger) GW170818 GW170823 GW190412 GW190521 (first-ever light from bh-bh merger) GW190814 (first-ever "mass gap" collision)
Methods
Direct detection
Laser interferometers Resonant mass detectors Proposed: Atom interferometers Indirect detection
B-modes of CMB Pulsar timing array Binary pulsar
Theory
General relativity Tests of general relativity Metric theories Graviton
Effects / properties
Polarization Spin-flip Redshift Travel with speed of light h strain Chirp signal (chirp mass) Carried energy
Types / sources
Stochastic
Cosmic inflation-quantum fluctuation Phase transition Binary inspiral
Supermassive black holes Stellar black holes Neutron stars EMRI Continuous
Rotating neutron star Burst
Supernova or from unknown sources Hypothesis
Colliding cosmic string and other unknown sources
Hellenica World - Scientific Library
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