LIGO Document E1400150-x0

3rd IFO SUS ETMX Acceptance Document

Document #:
Document type:
E - Engineering documents
3rd IFO SUS ETMX Acceptance Document

Reviewed by committee 10th Dec 2014. Actions on Stuart, Norna and Arnaud.

S Aston (12/10/2014): It should be noted that, from the top-top TFs, the 2nd pitch mode on the reaction chains shifted by ~10% from the model, due to cable routing. This feature has been observed for all other QUADs. However, a similar magnitude shift is also seen in the 2nd pitch mode on the main chain, but only for 3rd IFO QUADs. The root cause of this shift is still unknown after having exhausted the most likely candidates, e.g. replacing the top mass blades, re-balancing the mass and verifying the suspension wire used.

11th Feb 2015 - This item is being accepted for Fabrication Acceptance.

Files in Document:
Notes and Changes:
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: Advanced LIGO Quadruple Suspension Assembly

ICS Assembly #:
- ICS Assembly Load:

Acceptance document:
This filecard serves as the acceptance document for 3rd IFO ETMX.
For common material for all QUAD suspensions, see

ICS inventory

Non assigned i.e. not applicable for units tested on a test-stand at Phase 1b.

Test results:
- Calibrated, M0toM0 & R0toR0 Transfer Functions (DAMPING OFF):

The ~1.45 Hz R0 Pitch mode is shifted from the model due to cable routing stiffening the suspension.

However, similar to other 3rd IFO QUADS, the M0 pitch DOF has 2nd peak modeled at 1.33Hz and measured at 1.45Hz i.e. shifted up by ~10%. See a comparison of different "wireloop" quads on:
As well as, further model fitting discussed in:

- Calibrated, M0toM0 & R0toR0 Transfer Functions (DAMPING ON):

n.b. the damped model prediction presented is erroneous, however, the measurement data is correct, and consistent with the undamped model.

- Calibrated, L1toL1 and L2toL2 Transfer Functions (DAMPING ON/OFF): Not carried-out under Phase 1b testing, so not included here.

- Calibrated OSEM Sensor ASDs, All Stages (DAMPING OFF):

- B&K Hammer Cage Resonance Transfer Functions: Not carried-out under Phase 1b testing, so not included here.

- Coil Driver Noise:

- Coil Driver Response in all states:

- 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:
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.

Channel/Signal List and Calibrations
For latest measurements of OSEM Sensor's Open Light Current, See
Otherwise calibrations are assumed to be as shown in QUAD Control Design Description, with a roughly 20% uncertainty

Referenced by:

DCC Version 3.4.3, contact Document Database Administrators