Wideband laser-interferometer gravitational-radiation experiment
A wideband laser-interferometer gravitational-radiation antenna was constructed and used to search for gravitational radiation in the frequency band from 1 to 20 kHz. The antenna consisted of a Michelson interferometer with the beamsplitter and retroreflectors attached to masses on soft suspensions that allowed essentially free motion above the suspension frequencies. The strains in the gravitational radiation produce a differential path length change in the two arms of the interferometer which is detected by a pair of balanced photodetectors. The interferometer used a folded-path configuration with an effective length of 8.5 m. The sensitivity of the interferometer was calibrated with signals from a piezoelectric displacement transducer. The strain noise in a 1-Hz bandwidth was less than 0.3 fm/m from 1 to 3 kHz, and less than 0.1 fm/m above 3 kHz, where it was essentially photon-noise limited. (For comparison, the kT strain noise in a room-temperature, 2-m long, 1000-kg, elastic solid bar antenna is 0.14 fm/m.) The laser interferometer was operated as a detector for gravitational radiation for 150 h during the nights and weekends from the period 4 October through 3 December 1972. During the same period, bar antennas were operated by the Maryland, Glasgow, and Frascati groups, with 18 events reported by the Frascati group in their single bar, 22 single-bar events and no coincidences reported by the Glasgow group in their two bars, and 28 coincidences reported by the Maryland group between the Argonne bar and the Maryland bar and/or disk antennas. The various bar antenna systems were quite different but in general were sensitive to gravitational-radiation strain spectral components with an amplitude of the order of 0.1 fm/m in a narrow band of frequencies about the resonant frequency of the bar. The wideband interferometer data was analyzed by ear, with the detection sensitivity estimated to be of the order of 1--10 fm/m.
- Research Organization:
- Hughes Research Laboratories, Malibu, California 90265
- OSTI ID:
- 5035016
- Journal Information:
- Phys. Rev., D; (United States), Vol. 17:2
- Country of Publication:
- United States
- Language:
- English
Similar Records
A search for gravitational waves from coalescing binary stars using the Caltech 40 meter gravity wave detector
Comparison of bar and interferometer sensitivities to sources of transient gravitational radiation
Related Subjects
GENERAL PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
GRAVITATIONAL RADIATION
RADIATION DETECTION
GRAVITATIONAL WAVE DETECTORS
MICHELSON INTERFEROMETER
ANTENNAS
BEAM SPLITTING
EINSTEIN FIELD EQUATIONS
KHZ RANGE 01-100
LASER RADIATION
POLARIZATION
ELECTRICAL EQUIPMENT
ELECTROMAGNETIC RADIATION
EQUATIONS
EQUIPMENT
FIELD EQUATIONS
FREQUENCY RANGE
INTERFEROMETERS
KHZ RANGE
MEASURING INSTRUMENTS
RADIATION DETECTORS
RADIATIONS
640106* - Astrophysics & Cosmology- Cosmology
645400 - High Energy Physics- Field Theory