I have analyzed the IM OSEM signals from the May 19th ISI trip, while both the ISI and the IM optics were tripped, and have injected a step funtion into TEST PIT and TEST YAW to measure Q values.
Power Spectrums:
Length signals for IM1-4, and the signal for IM4 shows clean peaks for yaw and it's 1st harmonic and length and it's first harmonic. All other IMs have peaks that are lower than the peaks in IM4.
Q values:
I measured the length and yaw Q values for each IM, and my original post is alog 27327. In that post, I list pitch and yaw, however the resonant frequency I measured that's labeled as pitch is actually length.
IM4 shows the highest Q values for length and yaw, and comparing the Q values for IM1-3, they are all between 54% and 95% of the IM4 Qs.
Time Series:
The time series of the individual OSEM signals reveals a difference in amplitude in the oscillations of OSEMs, when comparing the four OSEMs on each optic.
I measured the period of oscillations for each OSEM on each IM, and in reality the period was not very enlightening, however, I also collected the oscillation amplitude of each OSEM near the end of the time the optic was tripped. The oscillation amplitudes proved to be very revealing, and show that the OSEMs on IM4, the IM that has never shown an alignment shift , have very different behavior than the OSEMs on IM1-3, that have all had significant alignment shifts.
Details / Summary of power spectrums for IM1-4: attachment 1
- all IMs, yaw and length peaks
- all IMs, yaw and length first harmonics
- all IMs, pitch and roll peaks
- IM4 yaw peak and it's 1st harmonic
- IM4 length peak and it's 1st harmonic
- IM1 yaw peak and it's 1st harmonic
- IM1 length peak and it's 1st harmonic
- IM3 yaw peak and it's 1st harmonic
- IM3 length peak and it's 1st harmonic
- IM2 yaw peak and it's 1st harmonic
- IM2 length peak and it's 1st harmonic
| IM1 length | 1.21 |
| IM2 length | 1.43 |
| IM3 length | 1.36 |
| IM4 length | 1.50 |
| IM1 yaw | 1424 |
| IM2 yaw | 1087 |
| IM3 yaw | 1270 |
| IM4 yaw | 2009 |
Details / Summary of oscillation amplitude data for IM1-4: attachment 2
IM4: no alignment shifts observed in my IM investigation, highest average percent of max oscillation at 94%
IM2: largest and most consistent alignment shifts observed, has the OSEM with the lowest percent of max OSEM oscillation at 70%
IM3: second largest alignment shifts, has the lowest average percent of max oscillation at 81%
IM1: smallest alignment shifts, one OSEM at 92%of max oscillation, others at 76% and 82%
