LIGO Document T1300397-x0
- ALIGO IO H1 HAM AUX Test Results
- IO review comments from Jeff Kissel (note these are repeated also in T1300680)
In General, for all IMs:
- Section 1.1
- Include the ICS reference in section
- Section 3.1
- Requirements say "> 10 [mrad]," yet this plot only shows up to ± 4 [mrad] over 1.5 or 3k DAC counts. Do HAUX use a 16-bit or 18-bit DAC?
- Section 3.4 and 3.7
- Include physical units on this plot.
- There must be at least displacement noise requirements at 10 [Hz]. Are they met (to as good as you can measure, if not a least model based on these results)?
- A good "requirement" to compare against is the AOSEM sensor noise floor. Do the high-frequency results asymptote to this noise floor?
- Is this entire spectra understood? What's the structure between 10 and 100 [Hz]?
- In what state was the ISI during these performance measurements? By context, it seems that the ISI was *off* during these measurements. Does the residual seismic motion roughly agree with what you expect from the estimated performance? It would be good to see the performance with a fully functional ISI.
- D'you have ASDs in the Euler basis?
- It would be useful to compare the ASDs of several suspensions in the Euler basis to compare and contrast their performance as a whole.
- Section 3.6 and 3.8
- All resonances appear to be lower that expected from the model. Has there been effort made to understand why?
- It would be useful to compare the TFs of several suspensions to compare and contrast their dynamics as a whole. E.g. H1 IM1 and H1 IM2 appear to significantly different pitch-to-pitch and pitch-to-length dynamics, both with and without eddy-current damping.
- All of these measurements are in-air. Before being accepted, the results must be demonstrated at vacuum, to at least be sure they're cleared of rubbing.
- Section 3.9
- When d'you expect these measurements to be completed?
- Other than the linearity tests, there seems to be no proof that the active control system can be used for damping / global feedback. Has it thus far been assume that one will rely solely on eddy-current damping for local damping?
The biggest problem I have with the results is that almost all of the performance data has not yet been taken at-vacuum. I see this as a critical portion of accepting that the SUS perform as designed, to spec, under there expected environmental conditions.
Specific comments to each:
- H1 IM3
- What's the course of action to investigate the odd pitch dynamics you see?
- H1 IM4
- Section 3.4 I'm confused as to why the requirements for IM4 are 4 ± 0.5 [mrad], where IMs 1-3 are 0 ± 0.5 [mrad]. Why is that?
DCC Version 3.4.1, contact