VIRGO

 

Collaboration:

Laboratory: EGO Cascina

National Responsible: F. Vetrano (Urbino/Fi)

Home page of the experiment: http://www.virgo.infn.it/

1. Goal of the experiment

The scientific goal of the experiment, after the end of the construction and the commissioning of the interferometric gravitational antenna Virgo (a suspended Michelson interferometer, with 3 km Fabry-Pérot cavities as orthogonal arms), is to reach sensitivity enough, to take data, to develop analysis strategy, in order to be able to detect gravitational waves from astrophysical and/or cosmological sources, provided their amplitudes are those predicted by currently accepted theoretical models.

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 The Virgo groups are also involved in some R&D activities, considered and managed as sub-projects aiming at insuring that projected sensitivity of Virgo will be reached and preserved, or else to improve Virgo sensitivity by reducing the noise. From this point of view, Virgo R&D is presently the most powerful effort to improve the performances of ground-based interferometric gravitational detectors at short- and medium –time.

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2.

Activities during 2002

Virgo experiment is beginning its activity in 2002, but it was preceded by a long Special Project (1994-2001), which was entirely devoted to the construction of the antenna with all related infrastructures. The commissioning of the Central Interferometer (a suspended 6 m Michelson interferometer without Fabry-Pérot cavities) has been ended in the Summer 2002, and many engineering runs have been performed: analysis of the produced data is now completed and furnished fundamental information about locking strategy to be followed for the 3 km detector too. The Assembly and Integration of the overall antenna is almost completed, even though for ending tower some activity on (final) test masses will be finished at the beginning of 2003. For what concerns R&D activities, LF Facility concluded a first run: acquired data are now being analyzed. The CRYSTAL sub-project received good financial support only during last summer: the hardware structure is just started and will be completed when all components will be delivered from companies. The UVVV activity has been unfortunately stopped due to problems on the laser: we are now ending all tests and we’ll be able to recover the delay reaching full operating state in the first half of 2003.

It is to be underlined that despite the lack of funds for calculus, some fundamental tests for distributed calculus have been performed on the clusters of FI/Ub-PG-NA-RM1 Sections.

The Collaboration is now involved in detailed Plan for the Commissioning of Virgo 3km.

The following achievements have been obtained:

Milestones 2003

Tests on catalytic gluing of fused silica-silicon for suspension wires-mirror system 30-04-2003
Implementation of both classic and adaptive control techniques on isolated mirrors 30-06-2003
Implementation of non-linear alignment and local control on Virgo 3 km 31-08-2003
Implementation and verification of final active filtering loops on every SA in Virgo 15-09-2003
Substitution of the LFF payloads with the final one 15-09-2003
First full tests on substrates for cold mirrors 31-10-2003
Final version and related upgrade of the system for measuring opto/mechanical transfer function on the last stage of SAs 30-11-2003
Run and related analysis on LFF data 15-12-2003
Stability and performance tests on the prototype for adaptive optics control 31-12-2003
Preliminary tests on electrostatic pushers and related electronics on a suspended mirror 31-12-2003
End of debugging and of commissioning crucial phases for Virgo 3 km 31-12-2003
Ending of Assembly and Integration Virgo 3 km 31-01-2003

 

3. INFN contribution to the experiment in terms of manpower

Manpower: 73 researchers (55.1 FTE), 18 technicians (7.6 FTE)

Budget for the Year 2003: 5.7 % of the CSN2 budget for 2003

4. Publications in refereed journals (year 2002): 7

5. Conference talks (year 2002): 6

6. Number of undergraduate and doctoral theses on the experiment: 12

7. Leadership roles in the experiment

8. Innovative instruments

9. Competing experiments

10. International Committee which has reviewed the experiment

Scientific and Technical Advisory Committee (EGO STAC)