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CNRS/EGO
joint Press Release
Claudie Haigneré, the French Minister
for Research and New Technologies, and Letizia Moratti, Italy's Minister
for Education and Research, will inaugurate the gravitational wave detector,
VIRGO, on July 2003, in Cascina, Italy, near Pisa. Geneviève Berger,
Director General of the CNRS, will be present at the ceremony, in addition
to Enzo Larocci, President of the Istituto Nazionale di Fisica Nucleare
and Filippo Menzinger, Director of EGO (European Gravitational Observatory).
VIRGO is a high technology instrument, the
fruit of a partnership between the CNRS and the Italian National Institute
of Nuclear Physics (INFN). VIRGO is designed to experimentally detect
the gravitational waves predicted by Albert Einstein's general theory
of relativity. It is thought that these waves are produced by violent
cosmic events such as the explosion of a supernova or the fusion of two
neuron stars or black holes. These waves travel at the speed of light
through space and matter. The difficulty lies in detecting them because
of their very low amplitude, presenting an extraordinary scientific and
technological challenge.
VIRGO is a laser interferometer consisting of two perpendicular arms,
three kilometers long, within which a laser beam circulates, split into
one beam per arm. Each of these beams is subject to multiple reflections
between two mirrors located at both ends of the two arms. These "beam
dividing" mirrors form resonant cavities before being sent to interfere
on the same detector. Their interference is seen as a varying degree of
light at the exit of the interferometer, depending on the difference in
length between the two optical paths. If, in the absence of gravitational
waves, these lengths are identical, the arrival of such a wave will modify
them infinitesimally, causing a variation in the luminous flow resulting
from the interference. This variation will only be measurable if the amplitude
of the wave is adequate, the aim being to obtain a sensitivity that would
make it possible to identify a path difference on the order of 10-18 meters,
that is, a thousandth of the size of an atomic nucleus. The extreme sensitivity
of VIRGO is the result of a series of technological advances: the optical
quality of mirrors, the seismic insulation system, the stability of laser
radiation, as well as the quality of the ultra-high vacuum required within
the two arms of the interferometer.
Begun in 1996, the construction of VIRGO was only recently completed.
Five CNRS laboratories and six laboratories of the Italian National Institute
of Nuclear Physics participated in its development and construction. Initial
tests are in progress and should continue for approximately one year.
EGO, the European Gravitational Observatory, was created in 2000 to ensure
the end of the construction of the instrument and its long-term operation.
This Franco-Italian consortium is also responsible for promoting an active
policy of research and development in the field of gravitational waves.
Press contact
:
Martine Hasler
Tel : +33 1 44 96 46 35
e-mail : martine.hasler@cnrs-dir.fr
EGO
contact
Daniel Enard
Tel: Tel: +39 050 75 2520
E-mail: daniel.enard@ego-gw.it
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