- ITMX de-install ongoing, the SUS crew began taking things apart yesterday and possible use of the arm today
- TCS wants to go in and follow up on the RH 24-hour test
- HAM6 work with Dan, Corey, and Keita is progressing with the help of Hugh. They moved a masses into place yesterday.
- CPB build ongoing with Mitch
- Richard is continuing to look at AI and AA chassis
- Ongoing ISS array work in the H2 PSL enclosure
model restarts logged for Wed 04/Jun/2014
2014_06_04 15:13 h1broadcast0
2014_06_04 15:13 h1dc0
2014_06_04 15:13 h1fw0
2014_06_04 15:13 h1fw1
2014_06_04 15:13 h1nds0
2014_06_04 15:13 h1nds1
no unexpected restarts.
J. Kissel While it has reported that the electrostatic drive is under what is expected by factors of 2, 4 and 8, repeated attempts at measuring and understanding the actuation strength of the ESD have at least garnered quite a bit of understanding on my part. The message: A factor of 8 is wrong -- a result of me misinterpreting how the actuation coefficient was calculated. A factor of 2 and 4 are still plausible, because all measurements have been made using the green ALS system, whose optical gain can vary significantly over the course of the measurement from alignment fluctuations. The latest comparisons of all H1 ETMX and H1 ETMY swept sine transfer functions report a quantitatively rigorous factor discrepancy (with uncertainty) below the expected actuation strength by factors that are indeed between 2 and 4. Many details below. Details ------- All published efforts to-date that attempt to quantify the actuation strength the ESDs: aLOG Meas Date Optic DOF Drive Bias [ct_DAC]/[V_ESD] Response Channel [units] Factor below 4.2e-10 [N/V^2] ---- --------- ----- --- --------------- --------------------- ------------------------ ---------------------------- This aLOG 2014-04-28 ETMX L 1.0-20 [Hz] Swept Sine +125e3 / +381 ALS-C_COMM_PLL_CTRL_OUT [Hz] 2.26 +/- 0.012 2014-04-30 ETMX L 0.1-10 [Hz] Swept Sine +125e3 / +381 ALS-X_REFL_CTRL_OUT [kHz] 3.66 +/- 0.007 2014-05-29 ETMY L 0.1-10 [Hz] Swept Sine -125e3 / -381 ALS-Y_REFL_CTRL_OUT [um] 2.97 +/- 0.005 LHO aLOG 11929 2014-05-16 ETMX L 11 [Hz] Sine Wave +125e3 / +381 ALS-X_REFL_CTRL_OUT [kHz] 8 INCORRECT ANALYSIS LHO aLOG 12109 2014-05-16 ETMX Same measurement, reprocessed with better understanding 2 CORRECTED ANALYSIS LHO aLOG 11676 2014-04-30 ETMX L Same measurement in this aLOG, reprocessed with uncertainty analysis 4 (consistent with above) LHO aLOG 11581 2014-04-28 ETMX P,Y 1.0-20 [Hz] Swept Sine +125e3 / +381 EX Oplev [urad] 2ish (consistent with above) Possibly contains actuation strength, but quadrant information is too cross-coupled to obtain a pure P/Y number in terms of force: LHO aLOG 12026 2014-05-22 ETMX UL, LL, UR, LR 3 [Hz] Sine Wave (+124e3 0 -124e3) / (+377 0 - 377) EX Oplev [urad] Difficult to say LHO aLOG 12027 2014-05-22 ETMY UL, LL, UR, LR 3 [Hz] Sine Wave (+124e3 0 -124e3) / (+377 0 - 377) EY Oplev [urad] Difficult to say Unpublished attempts: L1/ETMX/SAGL3/Data/2014-05-30_0800_L1SUSETMX_L3_L2LPY_SweptSine.xml -- coherence deemed too poor because ALS noise too high. L1/ETMY/SAGL3/Data/2014-05-30_0800_L1SUSETMY_L3_L2LPY_SweptSine.xml -- coherence deemed too poor because ALS noise too high. H1/ETMX/SAGL3/Data/2014-05-15_H1SUSETMX_L3_ESD_P_2Hz.xml -- attempted to process, but got a factor 8 to 10, and gave up deciding torque was too hard H1/ETMX/SAGL3/Data/2014-05-15_H1SUSETMX_L3_ESD_P_3Hz.xml -- "" H1/ETMX/SAGL3/Data/2014-05-15_H1SUSETMX_L3_ESD_Y_2Hz.xml -- "" H1/ETMX/SAGL3/Data/2014-05-16_H1SUSETMX_L3_ChargeTest_LL.xml -- attempted to take quadrant-by-quadrant data, but did not process before 2014-05-22 measurements, then gave up H1/ETMX/SAGL3/Data/2014-05-16_H1SUSETMX_L3_ChargeTest_LR.xml -- "" H1/ETMX/SAGL3/Data/2014-05-16_H1SUSETMX_L3_ChargeTest_UL.xml -- "" H1/ETMX/SAGL3/Data/2014-05-16_H1SUSETMX_L3_ChargeTest_UR.xml -- "" On the linear dependence of longitudinal Force, F on Control Voltage, V_CTRL: We know F = a (V_CTRL - V_BIAS)^2 = a (V_CTRL^2 - 2*V_CTRL*V_BIAS + V_BIAS^2) for a given bias voltage V_BIAS. For all of the above analysis, as a given frequency, we apply a sinusoidal control voltage at some frequency, w and amplitude V_0. As such, because of the quadratic nature of the actuator, F = a (V_0^2*sin^2(wt) - 2*V_0*V_BIAS sin(wt) + V_BIAS^2) [sin^2(wt) = 1/2 - 1/2*cos(2wt) + O(4w)] = a (V_0^2*[1/2 - 1/2*cos(2wt)] - 2*V_0*V_BIAS sin(wt) + V_BIAS^2) = [(a/2)*V_0^2 + a*V_BIAS^2] - [2*V_0*V_BIAS*sin(wt)] + [(a/2)*V_0^2*cos(2wt)] F = [ DC term ] [ linear term ] [ bilinear term ] Now, for a transfer function (i.e. a linear cross-correlation function), only the linear term will show up, such that F_lin = - 2*V_0*V_BIAS*sin(wt), or in the frequency domain, simply, F_lin = - 2*V_0*V_BIAS. Thus, at a single frequency, the linear transfer function coefficient magnitude between force and control voltage is F_lin ----- = 2*a*V_BIAS V_0 And this is exactly the function one must use to calibrate the drive component of the electrostatic drive chain, assuming the above equation is defined where V_CTRL and V_BIAS are in units of [V] on the electrodes in-vacuum. Tracing these back to the digital drive points for the bias voltage, ct_BIAS, and for control voltage ct_LOCK, where V_0 = G_ESD * G_DAC * EUL2ESD * ct_LOCK V_BIAS = G_ESD * G_DAC * ct_BIAS where G_ESD = 40 [V/V] is the gain of the ESD driver, G_DAC = 20/2^18 [Vpp/ct] is the DAC gain, and EUL2ESD = 0.25 is the coefficient in the Euler to ESD basis transformation output matrix. This leaves the calibration to be F_lin ------- = 2 * a * G_ESD^2 * G_DAC^2 * EUL2OSEM * ct_BIAS = 2.44e-10 [N/ct] ct_LOCK assuming a bias equivalent voltage of 125e3 [ct_BIAS], as all of the above mentioned values are quoted. As a reminder, the control voltage used in this calculation is the control voltage on one quadrant, even though you're drive all four quadrants. As a is defined above, the longitudinal force is generated by the potential difference between the ring of control voltage and the ring of bias voltage. That ring of control voltage is held at the same voltage for all four quadrants, and hence one quadrant is representative of the ring (see LHO aLOG 12109 for further description). Calibration of each measurement's response channel newly described in this aLOG Since three different people took swept sine TFs, with sensors each having different calibrations that were changing over time, it took a bit of work to calibrate all the transfer functions into [m]. - The calibration for ALS-C_COMM_PLL_CTRL_OUT, though it claimed to be in (green) [Hz] had not had the VCO response removed (as confirmed by a trend of the H1:ALS-C_COMM_PLL_CTRL_SWSTAT, which showed that the compensation filter in FM3, "antiVCO" was OFF during the measurement), so my calibration from [Hz/ct] to [m/ct] was [m/ct] = L * (lambda_g / c) * zpk(-2*pi*40,-2*pi*1.6,1.6/40) * (H1:ALS-C_COMM_PLL_CTRL_OUT_DQ / H1:SUS-ETMX_L3_LOCK_L_EXC) - The calibration for ALS-X_REFL_CTRL_OUT was similar, but this had the VCO response removed, so the only difference is the order of magnitude, [m/ct] = L * (lambda_g / c) * (H1:ALS-X_REFL_CTRL_OUT_DQ / H1:SUS-ETMX_L3_LOCK_L_EXC) - Finally, ALS-Y_REFL_CTRL_OUT had been calibrated graciously into displacement units, so one merely had to adjust the order of magnitude, [m/ct] = (H1:ALS-X_REFL_CTRL_OUT_DQ / H1:SUS-ETMX_L3_LOCK_L_EXC) Uncertainty Estimation I've folded in the coherence to assess the uncertainty at frequency point for the magnitude and phase of the transfer function as described in LHO aLOG 12109, meas.unc.radians = sqrt( (1 - meas.coh ./ (2*nAvgs*meas.coh ); meas.unc.m_per_N = abs(meas.tf.m_per_N) * meas.unc.radians; Once these are obtain, I find the residual between the model and measurement, propagating the uncertainty assuming the model has no uncertainty, residual.tf = model.tf / meas.tf; residual.unc = abs(residual.tf) * meas.unc.radians; And then compute the weighted mean of each frequency point to arrive at the factor under the expected force coefficient value of 4.2e-10 [N/V^2], residual.weightedmean = sum( abs(residual.tf) ./ residual.unc.^2 ) / sum( 1 / residual.unc.^2 ) with uncertainty residual.weightedmean = sqrt( 1 ./ sum( 1 / residual.unc.^2 ) Now, one can justifiably argue that the reducing the obviously frequency-dependent residual down two one number, assuming that each frequency point is an independent measure of the actuation coefficient with merely statistical variations about some true mean value is not strictly correct. I agree -- there are still plenty of systematics at play that cause even a single measurement sweep to vary by as much as a factor of 2 over the frequency span of the measurement. There are several systematic errors that have *not* been accounted for in the model: (1) The undamped dynamical model is not strictly correct at the first pitch mode at ~0.5 [Hz]. This means, that -- though the current damping filters are used in the model -- the resulting closed-loop model of the damped QUAD is not perfect. However, this should only be a discrepancy right around the resonances, and certainly not a source for an overall scale factor (2) The optical gain of the interferometric sensors varies as much as a factor two during the 2014-04-30 H1 EX measurement (see attachment 2014-04-30_H1ALS_X_NormalizedTransmission.png). The sweep was performed from high to low frequency, and is likely the source of the drops in coherence / increase in uncertainty, especially at low frequency. This also may be the source of some apparent frequency dependence. Welp. It's 2am. I'm impressed you read this far. Go get some coffee, you deserve it. G'morning!
The script used to generate plots for this aLOG can be found here: /ligo/svncommon/SusSVN/sus/trunk/QUAD/Common/MatlabTools/plotallquad_dtttfs_L3.m The locations of the swept sine measurements plotted in this aLOG have been discribed in their original entries, but I repeat them here for your convenience: /ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGL3/Data/ 2014-04-28_H1SUSETMX_L3_L2LPY_SweptSine_1to20Hz.xml 2014-04-30_H1SUSETMX_L3_L2LPY_SweptSine.xml /ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMY/SAGL3/Data/ 2014-05-29_H1SUSETMY_L3_L2LPY_SweptSine.xml All are committed to the SusSVN as of this entry.
Just to note- since we are using the VCO calibration and you are making measurements way below the ugf of the green PDH loop, the changing optical gain doens't have any effect on your measurements.
There were many ETMX and EMTY ISI trips in the last two days almost all were due to me driving, most of those happened when the dtt session ended, either manually or because it reaches the number of averages, either way it trips the ISI.
There was one earthquake trip at about 5am this morning
Chris and I were looking at the TF from ISI to OPLEV tonight and as part of that we imrpoved the diagnolization of the OPLEV, the axis was about 3 degrees off
The old matrix was +/-1s the new one is
-0.9565 0.9565 -1.0417 1.0417
1.0417 -1.0417 -0.9565 0.9565 (shown in figure)
we got about a factor of 10 improvement (blue vs orange line)
there is room for further improvement if needed
Jeff Kissel, Thomas Vo
Jeff pointed out to me today in light of the RH test this past weekend that the ITMY optical lever gain is a factor of 2 different than the ITMX optical lever. We're inclined to trust the ITMX calibration because Keita made a pretty accurate measurement using the baffle PDs and the entire 4 km arm. I also remember specifically changing ITMX &ETMX gains to match Keita's measurement, but I don't remember doing ITMY/ETMY.
Anyway, Y-arm optical levers have to be checked once we get an arm again.
Dan, Corey, Keita, Hugh, Jeff
Today we started the HAM6 installation procedure outlined in T1400385. After the north and south doors came off (and the east door was put back on), Hugh installed ISI ballast on the business end of the table while Corey checked cables. We found we were missing two cables, to carry the OMCR-QPD and AS-C-QPD signals from the brackets on the table to the flange (cables 4 and 10, in section 6 of the procedure). Also, we discovered a discrepancy between the flange layout document (D1002877) and the WHAM6 cable configuration (D1300122). The flange layout correctly assigns feedthrough D5-3C to the purge air, and the WFS head cables exit the chamber through D3-2C. According to the cable configuration the WFS head cables are going through the purge air feedthrough.
Another small discrepancy is the assignment of the OMC DCPD and PZT cables in bracket CB-1, on the top of the OMC suspension cage. The cables are swapped from the locations prescribed in D1300122; the DCPD cable is on the second floor, the PZT cable is on the first floor. (The connections at the flange are correct, so no worry of powering the DCPDs with the PZT drive.) We tried to correct the bracket arrangement but discovered that the PZT cable is too short to reach the second floor of the bracket, so we left things as we found them.
We found two spare cables with Betsy for the OMCR and AS QPDs and attached those to the flange and the brackets. The OMC suspension was moved flush against the cookie cutter, and we installed & torqued the dog clamps. (The dog clamps are the incorrect height, but this seems to be a systemic issue.)
Now that we have finished verifying the cable connections by eye, the next steps are (not necessarily in this order):
We may need to switch between moving sleds/optics and installing ballast mass as we move through the procedure.
(Betsy, Travis, Danny, Margot)
Today we (undid some work! - ha):
- Swung the ACB back with it's swing-away hardware
- Put a TFE cap on the TCS steering mirror right in the line of foot-traffic and floor removal for protection
- Removed the stiffening braces and wedges (and ~40 fasteners) from the ITMx QUAD
- Removed 3 of the floor panels and removed the sleeve stiffening structure from the QUAD
- Started disconnection of all top stage OSEMs and cabling to lower stage OSEMs on QUAD
- Staged the QUAD hanger hardware and elevator adapter parts
- Richard swapped out my dead backup PS for the elevator - thx, RM for promptness
- Collected the witness plates/samples from BSC 1 and cleaned flooring there
Jim apparently attempting to hang himself from a support tube:
Travis breaking back - you can either see it or get an arm in there to adjust it, but you can't do both:
Besides the sleeve and pile of larger parts removed from a QUAD during chamber de/installation (shown in picture above), following is a picture of all of the fasteners, nuts, etc that also get removed from the QUAD (the pan was empty when we started):
Kind of thin reporting, I was in and out a lot. TVo and Hugh were in the Control Room most of the day to cover, as well. 10:30 Betsy to ITMX 10:45 I followed soon after 14:30 JeffB Andres to HAM6 15:12 Dave restarting DAQ
15:12PDT. DAQ restart. To support h1isiham5 model change and add channels to the broadcaster for DMT.
I have asked this before, but once again -
Yesterday, the BSC installation arm was put on the BSC3 door. The annulus plumbing and the cable trays prevented the flange stiffener to be attached in the correct spot, so it was rotated 1 flange-hole down. The arm is in the appropriate place on the flange, however. The 5-axis lift table and QUAD elevator were then mounted on the arm.
This morning, Margot and Danny took swipe samples of some of the BSC3 chamber surfaces and then cleaned the floors. Jim locked the ISI (see his entry). Travis and I rearranged the furniture such that we can work efficiently and then plumbed in the electrical to the elevator in prep for starting deinstall this afternoon.
I have a script which reports if a model's filter file has been modified since last loaded, or was partially loaded (with the potential that other filters in the file have not been loaded). I'm thinking of running this at the end of every Tuesday maintenance to remind subsystem personnel if reloads are needed. Pending filter changes should be applied as soon as is possible, model restarts, power outages and RCG upgrades will load the latest filter files.
here is the output from the script for today
h1isiham2: has modifed IIR file, investigate any prior loads
h1isiham3: has modifed IIR file, investigate any prior loads
h1isiitmy: has partial load, further investigation is required (last load was ITMY_ST1_T240SUBTRACT_Z Complete)
h1hpiitmy: has partial load, further investigation is required (last load was ITMY_ISO_HP Complete)
h1hpiitmx: has partial load, further investigation is required (last load was ITMX_SENSCOR_X_WNR Complete)
h1susitmy: has partial load, further investigation is required (last load was ITMY_M0_LOCK_Y Complete)
h1susbs: has modifed IIR file, investigate any prior loads
h1tcscs: has partial load, further investigation is required (last load was ITMX_CO2_QPD_B_SEG3 Complete)
h1lsc: has modifed IIR file, investigate any prior loads
h1asc: has modifed IIR file, investigate any prior loads
h1ascimc: has partial load, further investigation is required (last load was IMC_IM4_TRANS_SUM Complete)
h1susetmy: has partial load, further investigation is required (last load was ETMY_L3_ESDOUTF_DACCT_UR Complete)
h1susetmx: has modifed IIR file, investigate any prior loads
h1hpietmx: has partial load, further investigation is required (last load was ETMX_ISO_VP Complete)
Just finished locking ITMX. I remember this from last time, but just wanted to record some of the difficulties with locking the ISI's from below, in their current configuration. The ACB is VERY in the way (it's guaranteed I bumped it a few times), so I have to basically lean out over it a little (my spine does not make the proper S shape to make this easy) and Betsy's stool is a little too tall to slide under it. It would be a little easier if the current in-chamber stool was ~1 inch shorter, making it possible to slide under the ACB. The TCS mirror is also in the way, but it's manageable to work around, don't know if I touched it, I couldn't see because my head was jammed between the chamber side and St0 of the ISI.
I have created a python script which shows the local SVN status for model code (mdl and c files used to build a model). It shows local mods and optionally shows any pending updates from the SVN repository.
The script is called reportTargetCodeStatus.py, give it -h or --help to show usage
david.barker@sysadmin0: reportTargetCodeStatus.py --help
site is lho
usage: reportTargetCodeStatus.py [-h] [--showpending] targetname
Report status of all source code files associated with a given front end
target
positional arguments:
targetname the target to be reported
optional arguments:
-h, --help show this help message and exit
--showpending show code updates which are pending from the SVN repo
(requires kerberos ticket to be open)
david.barker@sysadmin0: reportTargetCodeStatus.py --showpending h1iscey
site is lho
target: h1iscey
showpending Program will slow while contacting svn repostory
Model last compiled: Tue Jun 3 10:52:58 2014
Model compiled using RCG: /opt/rtcds/rtscore/advLigoRTS-2.8.3
source file last modified svn_st Updates?
isc/common/models/LSC_END.mdl Thu Nov 14 16:56:17 2013 - -
isc/common/models/STATECOMM.mdl Thu Nov 14 16:08:57 2013 - -
isc/h1/models/h1iscey.mdl Tue Apr 29 17:51:56 2014 - -
isc/common/models/FILTBANK_TRIGGER.mdl Thu Nov 14 14:58:37 2013 - -
cds/common/src/wait.c Thu Apr 25 13:34:28 2013 - -
isc/common/models/ASC_END.mdl Thu Nov 14 16:56:17 2013 - -
cds/common/models/SCHMITTTRIGGER.mdl Thu Nov 14 14:50:26 2013 - -
cds/common/models/FILTBANK_MASK.mdl Thu Nov 14 14:50:26 2013 - -
isc/common/models/LSC_TRIGGER.mdl Thu Nov 14 14:58:38 2013 - U
isc/common/models/QPD.mdl Tue Mar 4 09:42:07 2014 - -
isc/common/models/ALS_END.mdl Tue Apr 29 09:52:21 2014 - U
isc/common/models/WFS.mdl Wed Dec 11 19:13:12 2013 - -
isc/common/src/RtCommunication.c Thu Nov 14 13:19:02 2013 - -
Betsy, Sheila, Keita, Arnaud, Thomas
Here is a snap shots of the current alingment offsets. This alingment was checked quickly this morning, both of the arms are flashing green so the ITMs are within a urad or so of alinged.
We noticed that the ailngment of ITMY was off by about 8 urad in pitch from the saved offset, this seems to be because turning on and off the ring heater changes the ailngments. Attached are trends of the OpLevs durring the ring heater stress test this weekend, the itms moved by 2-5 urad in yaw, and both moved by about 30 urad in pitch. The third screenshot shows how the pitch changed as the ring heater power cycled.
@DetChar -- can you grab calibrated ASDs of the optical levers before and after the ring heaters are on full blast? It looks like they not only displace the optic in angle, but also add noise. It would be good to quantify this early, so we can fix it!
I forgot to check this. https://dcc.ligo.org/LIGO-T1100184 Phil Willems wrote a document (T1100184) that predicted around 0.9urad of pitch per Watt of RH power. We applied 27W of power, so the Spurious Willems Pitch is around 24urad. This seems consistent with what was seen. It's worth a more detailed look though. I can't explain the 8urad offset between the start and finish.
From Jeff's request I've taken a look at the Oplevs before, during and after the heaters were on and found their ASDs (1st plot). These ADSs are taken over 10 minutes and the times are noted in the legend. I specifically chose times where the ITMY ISI ODC is reporting a good state. In addition the BLRMs look normal and similar for all three times. I also found the ground motion ASDs for these times (2nd plot) to reconfirm the ground motion is similar for all three times. Conclusion - the ASDs for the Oplevs look very similar before, during and after the heaters are on; they don't appear to add extra noise. There is perhaps an extra peak between 7-8Hz in the YAW when the heaters are on but other than that nothing stands out.
There is also a DC power level difference between states before after the weekend stress test. Based on the channel H1:TCS-C_RH_Y_LOWERCURRENT and Aidan's note of 27 W in the ramp up state, the forementioned DC offset correspond to a power level difference of ~8 W (assuming 0.55 for the current level during stress test and 0.3 before the stress test and 0 after the stress test, obtained from the plot of H1:TCS-C_RH_Y_LOWERCURRENT; 27 * 0.3^2/0.55^2). From the dcc documnet noted in the Aidan's comment this correspond to ~8 urd difference we between the initial and end states. This also means that we probably have to make new reference with the current setting (of zero current), if desired.
The ITMY ring heater was set to 8W during the past commissioning period to correct for the fact that we had an ETM with ITM coating installed. This will be changed in the current installation phase. New references will be rquired when we have the new optics installed and aligned.
Also note, the ITMs that this ring heater test was performed on are hung from metal wires in stead of glass fibers. I wonder if this is what is making them more susceptible to steering errors when the ring heater is engaged... The current install is to swap these ITMs out for new units complete with glass fibers. Hopefully the ITMs won't be as susceptible to mispointing when on fibers if this is the case.
J. Kissel As Betsy indicates these ITMs are suspended via steel wire instead of fused silica fiber. This plays a difference in the compliance used in the Phil's calculation of the expected displacement in T1100184. Also, the Willems calculation uses a QUAD suspension model from T1000263 which is an out-dated model parameter set that was never confirmed against real measurements (which we now have). Also it's unclear which Stage / DOF to Stage / DOF was used to produce the "pitch coupling" of 0.154 [rad/Nm]. The mathematica notebook that is "available from the author" is regrettably *not* zipped up in the "Other Files" on the DCC card, so I can't confirm. The attached .pdf doesn't have the 0.154 anywhere in the document. However, assuming the compliance he used was pitch displacement of the test mass from pitch torque on the test mass, the values from the production quad model model (now confirmed against measurement) are Fiber: 0.141 [rad/N.m] (using the quadopt_fiber.m parameter set) Wire: 0.105 [rad/N.m] (using the quadopt_wirerehang.m parameter set) Willems quotes the displacement of the Center of Mass (CoM) as 1.47e-7 [m] for 11 [W] of ring heater power. Assuming the displacement is linear with ring-heater power (safe assumption??), that's 1.34e-8 [rad/W] The displacement one expects per Watt of Ring heater power from the Willems model of a displaced CoM is then Fiber: 1.34e-8 [m/W] * 40 [kg] * 9.8 [m/s^2] * 0.141 [rad/N.m] = 7.4064e-07 [rad/W] = 0.74 [urad/W] Wire: 1.34e-8 [m/W] * 40 [kg] * 9.8 [m/s^2] * 0.105 [rad/N.m] = 5.5154e-07 [rad/W] = 0.55 [urad/W] And therefore at max power of 27 [W], the ITMs should be displaced by Wire: 5.5154e-07 [rad/W] * 27 [W] = 1.4892e-05 [rad] = 15 [urad]. This is a factor of two less than what is seen in ITMX Pitch (the cleanest example). For ITMY, I don't think the test mass was allowed to reach equilibrium before the ring heater's power was changed during the power cycling, so it's more difficult to assess the displacement -- but I think it's much closer to 15 [urad] judging by when the test was turned off (presumably it was turned off to zero current, and not the equivalent of 8 [W] that it had been set to as Daniel indicates).
Jeff pointed out that the factor of two in the ring heater deviation could arise from the optical lever gain in ITMY being a factor of two smaller than ITMX. We trust the ITMX's optical lever calibration because its gain was measured using the baffle PDs and the entire 4km arm (noted in ALOG 10331) but it doesn't look like a similar procedure was done for ITMY, or at least we couldn't find an ALOG that indicated as such.