ROG

Home Page of the experiment: http://www.roma1.infn.it/rog/

ROG (the acronym stands for Ricerca Onde Gravitazionali – Gravitational Wave Research) is a collaboration which has designed and constructed two massive (M=2.3 tons) cryogenic resonant bar detectors: EXPLORER, cooled at 2 K, in operation at CERN since 1990, and NAUTILUS, cooled at the record temperature (for such massive bodies) of 0.1 K, in operation at LNF since 1995.

The goal is the detection and study of gravitational wave signals emitted by high frequency (kHz) cosmic sources, such as gravitational collapses with formation of neutron stars and black holes, coalescing binaries, fast pulsars and a stochastic background.

The principle of operation is based on the assumption that any vibrational mode of a resonant body that has a mass quadrupole moment, such as the fundamental longitudinal mode of a cylindrical bar, can be excited by GW.

The performances of the present cryogenic detectors are the consequence of many years of development. The use of cryogenics and superconducting techniques for noise reduction and signal transduction led to a 105 fold improvement in energy sensitivity over Weber’s original bars. The sensitivity is now good enough so that a serious search for gravitational wave bursts is underway using the international network of 5 resonant bar detectors (IGEC).

The duty cycle for EXPLORER and NAUTILUS is of about 80%, and their strain sensitivity (of the order of 10-22 Hz-1/2 at the resonance for NAUTILUS), should allow the detection of the strongest sources in our Galaxy and in the Local Group.

In parallel to the data taking, two intense R&Ds are conducted, with the goals of enlarging the bandwidth (using high coupling capacitive transducer and low noise dcSQUID amplifier) and of reducing the spuria (cryogenic suspension with sphere prototype).