LIGO Document E1400146-x0
- H1 SUS ITMX Acceptance Document
Reviewed by committee 3rd Dec 2014. Actions on Stuart, Norna and Arnaud.
Norna - List any punchlist items or actions here.
11th Feb 2015 - The following item is beyond the scope of Fabrication Acceptance however it was added to the fabrication acceptance punchlist so it could be tracked. Added to punch-list. Obtain damped TFs under vacuum (phase 3b) as and when it can be fitted around (high priority) commissioning activities at LHO. It is on to-do list for staff there.
- I. Committee (* indicates review chair)
Rich Abbott, Alastair Heptonstall, Calum Torrie*, Jeff Lewis, Fabrice Matichard, Celine Ramet.
II. Documents for Review (against list from M1100282)
Top Assembly Name:
D0901149 AdvLIGO SUS BSC3-H1, XYZ Local CS for ITMX
ICS Assembly #:
- ICS Assembly Load:
This filecard serves as the acceptance document for H1 ITMX.
For common material for all QUAD suspensions, see
- Calibrated, M0toM0 & R0toR0 Transfer Functions (DAMPING OFF): https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=14729
- No Calibrated, M0toM0 or R0toR0 Transfer Functions (DAMPING ON). However, damped spectra below demonstrate damping is functional.
n.b. taking these TF measurements is on the to-do list for staff at LHO, and will be done when it can be fitted around commissioning activities.
- Calibrated, L1toL1 and L2toL2 Transfer Functions (DAMPING OFF): https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=13189
n.b. a factor of 2 discrepancy was later found in the model, which did not appropriately account for the motion of the reaction chain. Also, at the time of the comparison, the model did not account for the dynamics of the reaction chain which would explain the extra resonances seen in the measurement. The attachment of the following log shows a corrected model, compared with ITMY: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=13199
- Calibrated OSEM Sensor ASDs, All Stages (DAMPING ON/OFF): https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=15310
n.b. sensor noise floors look OK for all but the OSEM channels on the L1 (UIM) stage (LL, LR, UR, UL). Both in-air and previous in-vacuum measurements exhibit the same effect. However, after being converted into EULER DOFs for the L1 stage (L, P, R) noise is consistent with our expectations. This suggests a filter configuration or scaling issue associated with the measurement itself is the problem.
Also note that, by comparing undamped & damped spectra it can been seen that suspension modes are being damped in each DOF.
- B&K Hammer Cage Resonance Transfer Functions: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=8517
- Coil Driver Noise: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=3748
- Coil Driver Response in all states: https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=4495
- ESD Driver Noise: Not in the scope of this acceptance review, therefore not included here.
- Violin Mode Frequencies and Q
Measured violin modes: Not measured.
- Summary of modeled violin modes: https://dcc.ligo.org/LIGO-T1300876
Measured violin mode Qs are used to estimate wire losses (structural and thermo-elastic) and hence expected thermal noise at lower frequencies. Additional data will be taken and subsequent analysis is still to come, but this falls outside of the scope of the fabrication acceptance review.
Note added 2nd Dec 2014 for clarification (NAR)
Predicted violin mode frequencies and Qs for all types of suspensions are given in T1300876. These can be compared to measured values.
Measuring Qs is not a requirement for SUS acceptance.
For Installation acceptance it has been agreed that we should measure Qs once for each major suspension type.
For quads we have measured Qs on L1 ITMY, see for example
including comments. The Qs are higher than seen at LASTI but results are plausible if surface loss has improved with time under vacuum.
There is ongoing commissioning work to investigate whether the quad violin modes are being rung up in some cases.
Channel/Signal List and Calibrations
For latest measurements of OSEM Sensor's Open Light Current, See https://dcc.ligo.org/LIGO-E1200343
Otherwise calibrations are assumed to be as shown in QUAD Control Design Description,
https://dcc.ligo.org/LIGO-T1100378 with a roughly 20% uncertainty
DCC Version 3.4.0, contact
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