Weber bar

A resonant detector is a type of detectors for gravitational waves, which have been attempts in the 1960s and 1970s, detection of such waves. These detectors are carried out the first such tests in English, even after Joseph Weber, who suggested this type of detector and the University of Maryland, College Park, Weber bars called.

Main element of the detector is an oscillatory test mass, the resonator. Resonators were in the first experiments aluminum cylinder with a diameter of about 20 cm to about 1 m and lengths of 1-2 m, and later plates were used. It was assumed that gravitational waves can move these masses to vibrate, and due to the resonant peak, even very small signals can be made measurable. The disadvantage of this approach is that such a resonator responds only to the units of the gravitational wave signal lying in the vicinity of the natural oscillation frequency ( natural frequency ) of the resonator.

, The resonator was suspended in a node of the vibration mode used; in the cylinders, the longitudinal vibration was measured in the center of the cylinder has its nodal surface. The suspension is performed so that vibrations of the environment as little as possible are transferred to the resonator. Therefore, the interference signal of the detectors mainly by the thermal noise was limited; which corresponds to an oscillation amplitude in the range of 10-16 m. The resonance frequencies of the detectors were 60-1660 Hz.

Initial reports Webers in the years 1968 and 1969 that two independent resonance detectors at a great distance actually at the same time ( in coincidence ) gravitational waves have been detected are probably due to interference effects that were not detected due to inadequate analysis of the data as such. In later experiments in various institutions no gravitational waves could be detected despite higher sensitivity. Attempts to detect with a double to the rotation speed of the pulsar in the Crab nebula tuned resonant gravitational wave detector of this source were unsuccessful.