Kazuhiro YAMAMOTO, Shigemi OHTSUKA, Keita KAWABE, Kimio TSUBONO

Thermal noise is one of the principle noise sources of the gravitational wave detectors. It is significant to estimate and to study the strategy to reduce thermal noise.  Therefore, the various factors which effect the thermal noise have been considered.  However, the relationship between the thermal noise and the distribution of the losses has not been researched fully.  In this talk, the results of the investigation about the thermal noise by the inhomogeneous loss.

At first, it is discussed how the distribution of the losses affect  the thermal noise. The mode expansion is not appropriate to estimate the thermal noise of the system with the inhomogeneous dissipation. Recently, the new methods to calculate the thermal noise by the inhomogeneous loss are developed. This methods predict several interesting results. Moreover, the methods are tested by measuring the thermal noise of the known distribution of loss.  These results will be reported.

Then, how to detect the distribution of the losses are considered. To get information of the distribution  is essential in order to evaluate how the dissipation contribute the  thermal noise.  The method to investigate the distribution and the test of the  this method using the known distribution loss will be reported.