Each optical component of the interferometric gravitational wave detector VIRGO is suspended from a cascade of mechanical filters designed to suppress the transmission of seismic vibrations. Each mechanical filter supports the weight of the filters below it by means of a set of steel cantilever blade springs. The stress from the load acting on the blades was found to induce a drooping of the blade tips of several microns per day due to a series of microscopic yielding events (micro-creep). This process induces a mechanical displacement shot-noise on the optical component which can dominate the small displacements produced by gravitational waves. The use of a special precipitation hardened steel (Maraging C250), instead of common spring steel, allows the construction of blades that show an acceptable stability under stress.
Beccaria M, Bernardini M, Braccini S, Bradaschia C, Cagnoli G, Casciano C, et al. (1998). The creep problem in the VIRGO suspensions: a possible solution using Maraging steel. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION A, ACCELERATORS, SPECTROMETERS, DETECTORS AND ASSOCIATED EQUIPMENT, 404(2-3), 455-469 [10.1016/S0168-9002(97)01123-6].
The creep problem in the VIRGO suspensions: a possible solution using Maraging steel
Cuoco E;
1998
Abstract
Each optical component of the interferometric gravitational wave detector VIRGO is suspended from a cascade of mechanical filters designed to suppress the transmission of seismic vibrations. Each mechanical filter supports the weight of the filters below it by means of a set of steel cantilever blade springs. The stress from the load acting on the blades was found to induce a drooping of the blade tips of several microns per day due to a series of microscopic yielding events (micro-creep). This process induces a mechanical displacement shot-noise on the optical component which can dominate the small displacements produced by gravitational waves. The use of a special precipitation hardened steel (Maraging C250), instead of common spring steel, allows the construction of blades that show an acceptable stability under stress.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
