The first plot shows the current contribution to Hrec of the four crossbar modes at 48 Hz. It is obtained rescaling four spectra of Hrec measured during the noise injections performed in October (some peaks are slightly shifted). The applied scaling factors are about 100 times larger than the ones needed in order to project the supposed current flowing in the actuators in clean conditions, therefore the level of the peaks is still not explained. Moreover, the largest peak at 48.5 Hz does not match perfectly the projections as the other peaks, so we should not exclude a different source for that.

The second plot is the same with a different zoom. Trusting in it, one could assert that the contribution of the modes to the residual excess noise in that region is not so relevant, and a significant reduction of the mode quality factors, by the application of mechanical dampers, would not improve so much the situation. But again the mechanism which produces the main noise could be associated to the one which excites the modes, as it is for the one which has been removed today, so the investigation has to continue in the same direction.