Status of the AURIGA detector at Dec '04
On Dec. 1st
2004 additional mechanical filter have been integrated. As expected, the
lowering of the vibration noise in the 10 Hz - 30 Hz band corresponded to
the switching off most of the time of the spurious noise lines which were
affecting the gravitational wave sensitive band. In particular, AURIGA is
now stationary and the current typical noise performance is well explained
by the predicted noise contributions. The figure below shows the measured
one-sided spectral strain noise, in comparison with the predicted noise
sources: thermal noise of the mechanical and LC resonators, SQUID back
action and additive noises.
We plan to keep AURIGA in continuous observation in the present
configuration at 4.5 K until end of February 2005. Then the operation
temperature will be lowered to ~ 2 K, in an attempt to further increase the
sensitivity.
The additional mechanical filter has been installed between the floor platform and the cryostat. It is made of one stack of highly dissipative elastic material. Some correlation of the AURIGA noise with human activities is still noticeable. As a further improvement, we are preparing a mechanical suspension with a corner frequency close to 1 Hz, based on damped air-springs, to be installed without interruption of the cryogenic run.
