pep.covas@LIGO.ORG - posted 12:36, Tuesday 28 May 2019 (49504)
Measurements of HSTS bounce/roll modes
I've tried to measure again the bounce/roll modes of some of the HSTS. Instead of driving the four coils at the same time with a wide-band Gaussian noise excitation (as I did last time, which did not work), we have used only one coil at the same time with a more narrow excitation, as advised by J. Kissel.
The obtained data is located in the SUS svn:
- /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/PR2/SAGM2/Data/
- /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/PRM/SAGM2/Data/
- /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/SR2/SAGM2/Data/
- /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/SRM/SAGM2/Data/
- /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/MC1/SAGM2/Data/
- /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/MC2/SAGM2/Data/
- /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/MC3/SAGM2/Data/
The measured modes are (with resolution of ~0.01 Hz, 5 averages):
| Optic | Bounce mode [Hz] | Roll mode [Hz] |
| SRM | 27.45 | 40.88 |
| SR2 | 27.50 | 40.91 |
| PRM | 27.59 | 40.87 |
| PR2 | 27.41 | 40.94 |
| MC1 | 27.39 | - |
| MC2 | 27.74 | - |
| MC3 | - | - |
None of these bounce modes seems to be at the same frequency as the line at 27.71 Hz reported here.