Talk detail

Participant	Pashentseva, Maria
Institution	Lomonosov Moscow State University - Vorobyovi Gory - Moscow - Moscow - Russia

Session	GW3	Accepted		Order	Time
Talk	Poster abstract	Title	Measurement of mechanical excess noise from the stressed silicate bonding.
Co-authors
Abstract	The main goal of this work is an experimental search for excess mechanical noise which might be generated in a contact area of parts glued to each other by silicate bonding technique under external stress. This technique is an important method developed for the second generation of the ground based gravitational wave detectors. Although this technique is already used in AdvLIGO for the attachment of "ears" with suspension fibers to the test masses, the absence of additional non-gaussian noise caused by the bond area subjected by heavy load wasn't proved yet. The core of new installation designed for this experiment is a simple shadow sensor equipped with pump noise cancelation scheme. It will measure vibrations of the sample surface. Special care is taken in order to avoid any external influence, namely, whole frame for samples is made from fused silica and thermal expansion based stress technique is implemented. Although the planned sensitivity to the vibration amplitude: 10^(-13) m/sqrt(Hz) in the 60 Hz - 10 kHz bandwidth is incomparable with the upper limit of excess noises in AdvLIGO mirrors, very small samples and direct sensing in the points located very close to the bond area may allow to detect excess noise. It is planned to run series of tests on the samples with parts glued using silicate bonding process identical to the technique approved for the AdvLIGO test masses suspension. The next step planned is the application of the developed method to the another materials and bonding techniques. In particular, we are going to test the silicate bonding applied for silica-silicon and silicon-silicon contacts. Silicon is a candidate material for the third generation gravitational wave detector test masses. Shear strength measurements showed that silicon-silicon bonds are at least as strong as silica-silica, but the question about the excess noise from such a structure remains open.