download report - Sapienza

Scientific Report 2007-2009
Laboratories and Facilities of the Department of Physics
L18. The Gravitational Wave laboratory VIRGO
The Gravitational Wave laboratory of the university of Rome La Sapienza was founded by E. Amaldi and G. Pizzella
almost 40 years ago and is still at the frontier of this research field. At the foundation time the activity was focused on
the cryogenic resonant bar detectors. Here the first cryogenic GW antenna in the world was put in operation. Then the
laboratory was devoted to the study of new strategies for the detection of weak forces setting new linear and back action
evading transducers. Since 1996 the laboratory is devoted to support the VIRGO experiment and in particular to the design
and test of the last stage suspension system of the mirrors for the GW VIRGO interferometer (the payload).
Recently, in order to reduce further the thermal noise associated to the suspended mirror, we developed a payload based
on fused silica wires and we started to study the possibility to cool the mirror at cryogenic temperature. For this purpose
we are developing a vibration free cryostat, an active system which compensate the vibrations generated by the pulse tube
cryocooler operating at 5 K; we plan to use it also for testing the new cryo accelerometers for a very low frequency control.
The laboratory is equipped with a large variety of instrumentation and experimental facilities at the frontier of the present
technology. Two optical tables are used to set up the opto mechanical transducers dedicated to the remote control of the
payload degrees of freedom. High vacuum chambers and liquid helium cryostats of various dimensions, each one equipped
with oil free turbo molecular pumps, are dedicated to the test of each payload component. Moreover, because of the severe
constraint on the payload contamination, we set up for the final assembly phase a class 100 clean room inside which, thanks
to the use of an extra filtered air flow, we are able to achieve up to the class 1 cleanness.
Figure 1: On the left a lateral view of the VIRGO payload constructed and tested in GW lab. On the right the
vibration free cryostat installed in GW laboratory in Rome
Finally, for the VIRGO data analysis the laboratory installed the Tier 2 node of VIRGO: it consists of a LINUX farm of
416 cores and it includes a storage element of 16 TB spinning disks. This farm is the pilot of the VIRGO Virtual computing
organization and it is integrated in the INFN-Grid infrastructure.
http://www.virgo.infn.it/
Related research activities: P30.
Sapienza Università di Roma 189 Dipartimento di Fisica