40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  Engineering group Lab elog  Not logged in ELOG logo
Message ID: 237     Entry time: Wed Feb 26 14:40:52 2020
Author: Marie K. 
Type: Summary 
Category: BS BRDs 
Subject: BS Roll mode : BRD5_v5 & BRD6_v5 

====== Roll mode

Here is a summary of the BS roll mode survey with BRD5_v5 and BRD6_v6 attached to the suspension for 6 months.
Details of the measurements are attached in the spreadsheet.

The measured transfer functions over time are shown in figure 1. We observed two peaks in the data. This is in agreement with our model if the tuning if the BRD is within 0.1% of the BS roll mode (see T1900846).

  • Trend .  The mean frequency is Hz. The maximum excursion is +% and the minimum is -%.  
  • The Q of the mode is varying from to. Correlation with the frequency variations.

Therefore it seems that the bounce damping is pretty stable over 6 months. We didn't analyze correlations of the variations with environmental factors in the lab.

Measurements after taking off the BRD from BS:

Recall that pre-installation measurements were: 


ELOG V3.1.3-