Virgo Logbook

As already happened a few weeks ago, #63420, associated with the bad weather conditions of this morning and the large microseismic noise, there was an increased rate of scattered light glitches, best witnessed by LSC_SRCL, and reproduced by the V1:SBE_EIB_GEO_H2_200Hz channel.

Figure 1: spectrogram of a scattered light glitch in LSC_DARM.

Figure 2: Top: spectrogram of several scattered light glitches in LSC_SRCL. Middle: extracted arch frequency and predicted frequency of the scatterer surface according to the equation $f_{\text{fringe}} (t)=2n\frac{|v_{sc}(t)|}{\lambda}$ , with $\lambda$ the laser frequency, $v_{sc}$ the speed of the scatterer, equals to the time derivative of SBE_EIB_GEO_H2_200Hz channel, and $n$ the number of times stray light gets reflected back and forth between the test mass and the scatterer before it joins the main beam arXiv:2007.14876 . Notice that the y-axis is the same for both the reconstructed frequency of the arches and the predicted frequency. In the box, the value of the Pearson correlation coefficient between the two quantities, 80%. Bottom: time series of SBE_EIB_GEO_H2_200Hz.

We are currently running an extended analysis to find other correlated sensors, using the list of position, speed, and acceleration channels documented in this git issue.