Since the last post, I have found from the Characterization of TT data (from Jenne) that the resonant frequency of the cantilever springs for TT #4 (the model I am using) have a resonant frequency at 22 Hz. They are in fact inducing the 3rd resonance peak.

Here is a bode plot (CORRECTLY SCALED) comparing the rigidly-supported EDCs (model and experimental transfer functions)

Here is a bode plot comparing the flexibly-supported EDCs (model and experimental transfer functions). I have been working on this graph for FOREVER and with the set parameters, this is is close as I can get it (I've been mixing and matching parameters for well over an hour > <). I think that experimentally, the TTs have better isolation than the model because they have additional damping properties (i.e. cantilever blades that cause resonance peak at 22 Hz). Also, there may be a slight deviation because my model assumes that all four EDCs are a single EDC.

According to Rana, the following is the "new" (should always have been used, but now we're going to enforce it) earthquake stop backing-off procedure:

1. Back all EQ stops away from the optic, so that it is fully free-swinging.

2. Confirm on dataviewer that the optic is truely free-swinging.

3. One at a time, slowly move the EQ stop in until it barely touches the optic.  Watch dataviewer during this procedure - as soon as the time series of the OSEMs gets a 'kink', you've just barely touched the optic.

4. Back the EQ stop off by the calculated number of turns.  No inspections, no creativity, just math.  Each EQ stop should be between 1.5m and 2.0mm away from the optic.

5. Repeat steps 3 and 4 for each EQ stop.

Note: The amount that you need to turn the screws depends on what the threads are.

FACE and TOP stops are all 1/4-20, so 1.5 turns is 1.90mm

BOTTOM stops are either #4-40 or #6-32 (depending on the suspension tower).  If #4-40, 3 turns is 1.90mm.  If #6-32, 2.5 turns is 1.98mm

[Jamie, Jenne]

We went in to have a look-see at ETMY since it looked stuck-ish.  Jamie noticed that the side magnet was pretty close to the teflon plates of the OSEM.  We rotated it a bit, and now its all better.  We also adjusted the OSEMs until their mid-ranges were happy.  The U's were a little low, and the L's were a little high, as if the optic were a bit pitched backward.  Anyhow, we checked that the table is level, and tweaked the OSEMs.  We're starting the free-swinging test now...

Excited all optics

Fri Aug 12 17:38:53 PDT 2011
997231148

 Hmmm.  I'm no longer convinced that ETMY is healthy.  I think that when I gave it a kick, it's bouncing against something.  I can't fit the peaks to get the input matrix.  I guess step 1 is to try giving it a smaller kick for the free swinging spectra.  But if the owl shift folk feel like it, they might have a look-see.

Adjustment of the PRM OSEMs are done. The coils turned out to be healthy.

The malfunction was fixed. It was because the UL OSEM was too deeply inserted and barely touching the AR surface of the mirror.

(OSEM adjustment)

 + Excited POS at 6.5 Hz with an amplitude of 3000 cnts by the LOCKIN oscillator.

 + Looked at the signal of each sensor in frequency domain.

 + Maximized the excitation peak for each of the four face OSEMs by rotating them.

 + Minimized the excitation peak in the SIDE signal by rotating it.

 + Adjusted the OSEM translational position so that they are in the midpoint of the OSEM range.

(POS sensitivity check)

From the view point of the matrix inversion, one thing we want to have is the equally sensitive face sensors and insensitive SIDE OSEM to the POS motion.

To check the success level of today's PRM adjusment, I ran swept sine measurements to take the transfer function from POS to each sensor.

The plots below are the results.  The first figure is the one measured before the adjustment and the second plot is the one after the adjustment.

As shown in the plot, before the adjustment the sensitivity of OSEMs were very different and the SIDE OSEM is quite sensitive to the POS motion.

So PRM used be in an extremely bad situation.

After the adjustment, the plot became much better.

The four face sensors have almost the same sensitivity (within factor of 3) and the SIDE is quite insensitive to the POS motion.

I am leaving all of the suspensions free swinging. They will automatically recover after 5 hours from now.

--
Excited all optics
Sat Aug 13 02:08:07 PDT 2011
997261703
--

FYI : I ran a combination of two scripts:   ./freeswing && ./opticshutdown

I guess the ETMY suspension is still fine. Their OSEM DC voltage and the free swinging spectra look healthy.

It could be a failure in the initial guess for fitting.

As reported in my  previous entry of TT supsension bode plots, I found that my experimental data had what appears to be very noise peaks above 20 Hz (as mentioned earlier, the peak at 22 Hz is likely due to vertical coupling, as 22 Hz is the resonant frequency of the cantilever blades). This is very unusual and needs to be explored further. I would like to vertically-shake the TTs to obtain more data on possible coupling. However, I am leaving on Monday and will not return until Thursday (day of SURF talks). I am leaving campus Friday afternoon or so. I would may need some help coming up with an assembly plan/assembling set-up for vertical shaking (if it is possible to do so in such a limited time frame).

Today I wanted to see if the "noisy peaks" above 30 Hz were due to EM noise coupling. I tested this hypothesis today, seeing if EM fields generated by the coil at higher frequencies were injecting noise into my transfer function measurements. I found that the "noisy peaks" above 30 Hz are NOT DUE TO EM NOISE COUPLING. I am very curious as to what is causing the high peaks (possibly coupling from other degrees of freedom)?

Using my Matlab model of the flexibly-supported eddy current damping system, I have changed parameters to see if/how the TTs can be optimized in isolation. As I found earlier, posted in my bode plot entry, there is only a limited region where the flexibly-supported system provides better isolation than the rigidly-supported system.

Here is what I have found, where \gamma is the scale factor of the magnetic strength (proportional to magnetic strength), \beta is the scale factor of the current damper mass (estimated by attempting to fit my model to the experimental data), and \alpha is the scale factor of the current resonant frequency of the dampers.

Here are my commentaries on these plots. If you have any commentaries, it would be very helpful, as I would like to incorporate this information in my powerpoint presentation.

It seems as if the TT suspensions are already optimized?

It may be difficult to lower the resonant frequency of the dampers because that would mean changing the lengths of the EDC suspensions). Also, it appears that a rather drastic reduction (at most 0.6*current EDC resonant frequency --> reduction from about 10 Hz to 6 Hz or less) is required . Using the calculation that the resonant frequency is sqrt(g/length), for my single-suspended EDC model, this means increasing the wire length to nearly 3 x its current value. I'm not sure how this would translate to four EDCs...

The amplification at resonance caused by increasing the magnet strength almost offsets the isolation benefits of increasing magnet strength. From my modeling, it appears that the magnet strength may be very close (if not already at) isolation optimization.

Lowering the mass to 0.2 the current mass may be impractical. It seems as if the benefits of lowering the mass only occur when the mass is reduced by a factor of 0.2 (maybe 0.4)

What are the parameters you are using? As you have the drawings of the components, you can calculate the masses of the objects.

Reducing the ECD resonance from 10Hz->6Hz looks nice.

The resonant freq of the ECDs are not (fully) determined by the gravitational energy but have the contribution of the elastic energy of the wire.

Q1: How much is the res freq of the ECDs if the freq is completely determined by the grav energy? (i.e. the case of using much thinner wires)

Q2: How thin should the wires be?

 The drawings do not have the masses of the objects.

For the resonant frequency:

Instead of sqrt (g/l) would the numerator in the square root be[ g + (energy stored in wire)/(mass of damper)] ?

1) Drawing has the dimensions => You can calculate the volume => You can calculate the mass
Complicated structure can be ignored. We need a rough estimation.

2) Your restoring force can have two terms:
- one comes from the spring constant k
- the other from the gravity

 Thank you.

The wire used to suspend the EDCs is tungsten?

To verify, for my model, the EDC will be the mass of all four dampers or a single damper? The length of the wire used to suspend the EDC will be the combined length of 4 wires or length of  a single wire?

Taking into account the densities for each material (specific material of each component was listed, so I looked up the densities), and trying my best to approximate the volumes of each component, I have determined

the mass of the mirror + mirror holder to be ~100 g and the mass of a single EDC to be ~19 g

 I am thinking that perhaps my mass estimations were off? The model that I have used fits the data better than the model that I have made (changing the masses to fit my estimations of the values)

 I have been redoing the noise test multiple times today. Here is the best plot that I got

Excited all optics
Sun Aug 14 20:22:33 PDT 2011
997413768

[Suresh / Kiwamu]

 Adjustment of the OSEMs on BS has been done.

All the bad suspensions (#5176) has been adjusted. They are waiting for the matrix inversion test.

 Turns out I was missing a critical step in the process...running makeSUSspectra.m  After I do that, everything is back under control, and ETMY looks fine. 

I'm almost done doing the peak-fitting and matrix inversion for all optics.

The moral of the story here is that none of the suspensions are overwhelmingly awesome, but most of them will be fine if we leave them as-is.

SUS	DoF Plot	Input Matrix	"BADness" (1==good)
ITMX		pit     yaw     pos     side    butt UL    0.438   1.019   1.050  -0.059   0.717  UR    0.828  -0.981   1.128  -0.215  -0.956  LR   -1.172  -1.201   0.950  -0.275   1.241  LL   -1.562   0.799   0.872  -0.120  -1.087  SD   -0.579  -0.847   2.539   1.000  -0.170	4.68597
ITMY		pit     yaw     pos     side    butt UL    1.157   0.185   1.188  -0.109   0.922  UR    0.020  -1.815   0.745  -0.051  -0.970  LR   -1.980  -0.090   0.812  -0.024   1.158  LL   -0.843   1.910   1.255  -0.082  -0.949  SD   -0.958   1.080   1.859   1.000   0.325	4.82756
ETMX		pit     yaw     pos     side    butt UL    0.338   0.476   1.609   0.316   1.046   UR    0.274  -1.524   1.796  -0.069  -1.180   LR   -1.726  -1.565   0.391  -0.100   0.938   LL   -1.662   0.435   0.204   0.286  -0.836   SD    0.996  -2.629  -0.999   1.000  -0.111	4.32072
ETMY		pit     yaw     pos     side    butt UL    1.123   0.456   1.812   0.231   0.936  UR   -0.198  -1.489   0.492  -0.096  -1.098  LR   -2.000   0.055   0.188  -0.052   0.764  LL   -0.679   2.000   1.508   0.275  -1.201  SD    0.180  -0.591   3.355   1.000   0.200	10.643
BS		pit     yaw     pos     side    butt UL    1.575   0.697   0.230   0.294   1.045  UR    0.163  -1.303   1.829  -0.133  -0.958  LR   -1.837  -0.308   1.770  -0.171   0.944  LL   -0.425   1.692   0.171   0.257  -1.053  SD    0.769   0.345  -3.380   1.000   0.058	6.111
PRM		pit     yaw     pos     side    butt UL    0.597   1.553   2.000  -0.469   1.229   UR    1.304  -0.447   0.383  -0.043  -0.734   LR   -0.696  -1.048  -0.277   0.109   0.687   LL   -1.403   0.952   1.340  -0.317  -1.350   SD    0.518  -1.125  -1.161   1.000   0.394	8.43363
SRM		pit     yaw     pos     side    butt UL    0.831   1.039   1.153  -0.140   1.065  UR    1.071  -0.961   1.104  -0.057  -1.061  LR   -0.929  -0.946   0.847  -0.035   0.837  LL   -1.169   1.054   0.896  -0.118  -1.037  SD    0.193  -0.033   1.797   1.000   0.045	4.17396

I have updated the freeswing scripts, combining all of them into a single script that takes arguments to specify the optic to kick:

pianosa:SUS 0> ./freeswing
usage: freeswing SET
usage: freeswing OPTIC [OPTIC ...]

Kick and free-swing suspended optics.
Specify optics (i.e. 'MC1', 'ITMY') or a set:
'all' = (MC1 MC2 MC3 ETMX ETMY ITMX ITMY PRM SRM BS)
'ifo' = (ETMX ETMY ITMX ITMY PRM SRM BS)
'mc'  = (MC1 MC2 MC3)
pianosa:SUS 0>

I have removed all of the old scripts, and committed the new one to the SVN.

For some reason ETMY has changed a lot.  Not only does it now have the worst "badness" (B matrix condition number) at ~10, but the frequency of all the modes have shifted, some considerably.  I did accidentally bump the optic when Jenne and I were adjusting the OSEMs last week, but I didn't think it was that much.  The only thing I can think of that would cause the modes to move so much is that the optic has been somehow reseated in it's suspension.  I really don't know how that would have happened, though.

Jenne and I went in to investigate ETMY, to see if we could see anything obviously wrong.  Everything looks to be ok.  The magnets are all well centered in the OSEMs, and the PDMon levels look ok.

We rechecked the balance of the table, and tweaked it a bit to make it more level.  We then tweaked the OSEMs again to put them back in the center of their range.  We also checked the response by using the lockin method to check the response to POS and SIDE drive in each of the OSEMs (we want large POS response and minimal SIDE response).  Everything looked ok.

We're going to take another freeswing measurement and see how things look now.  If there are any suggestions what should be done (if anything), about the shifted modes, please let us know.

We did several things today+night.  The final goal was to lock the PRC so that we could obtain the POX, POY and POP beams.  However there were large number of steps to get there.

1) We moved the ITMY into its place and balanced the table

2) We then aligned the Y-arm cavity to the green beam which was set up as a reference before we moved the ETMY and ITMY to adjust the OSEMS.  We had the green flashing in Y-arm

3) We checked the beam position on PR2. It was okay. This confirmed that we were ready to send the beam onto the Y arm.

4) We then roughly aligned the IR beam on ETMY where Jamie had placed an Al foil with a hole.  We got the arm flashing in both IR and green. 

5) We used the PZTs to make the green and IR beams co-incident and flashing in the Y arm.  This completed the alignment of the IR beam into the Y-arm.

6) The IPPO (pick-off) window had to be repositioned to avoid clipping.  The IPANG beam was aligned such that it exits the ETMY chamber onto the ETMY table.  It can now be easily sent to the IPANG QPD.

7) Then BS was aligned to direct the IR beam into the X-arm and had the X-arm flashing.  It had already been aligned to its green.

8) It was now the turn of the SRC.  The beam spots on all the SRC related optics were off centered.  We aligned all the optics in the AS path to get the AS beam on to the AP table.

9) The AS beam was very faint so we repositioned the AS camera to the place intended for AS11 PD, since there was a brighter beam available there. 

10) We could then obtain reflections from ITMY, ITMX and PRM at the AS camera. 

11) Problems:

      a) ITMY osems need to be readjusted to make sure that they are in mid-range.  Several are out of range and so the damping is not effective.

      b) When we tried to align SRC the yaw OSEM had to be pushed to its full range.  We therefore have to turn the SRM tower to get it back into range.

 12)  We stopped here since moving the SRM is not something to be attempted at the end of a rather long day. Kiwamu is posting a plan for the rest of the day.

 Since Suresh and I changed the DC biases on most of the suspension, the free swingning spectra will be different from the past.

- -

EXcited ETMX ETMY ITMX ITMY PRM SRM BS

Tue Aug 16 04:48:02 PDT 2011
997530498

Data taken from: 997530498+120

Things are actually looking ok at the moment.  "Badness" (cond(B)) is below 6 for all optics.

• We don't have results from PRM since its spectra looked bad, as if it's being clamped by the earthquake stops.
• The SRM matrix definitely looks the nicest, followed by ITMX.  All the other matrices have some abnormally high or low elements.
• cond(B) for ETMY is better than that for SRM, even though the ETMY matrix doesn't look as nice.  Does this mean that cond(B) is not necessarily the best figure of merit, or is there something else that our naive expectation for the matrix doesn't catch?

We still need to go through and adjust all the OSEM ranges once the IFO is aligned and we know what our DC biases are.  We'll repeat this one last time after that.

TM		M	cond(B)
BS		pit     yaw     pos     side    butt UL    1.456   0.770   0.296   0.303   1.035  UR    0.285  -1.230   1.773  -0.077  -0.945  LR   -1.715  -0.340   1.704  -0.115   0.951  LL   -0.544   1.660   0.227   0.265  -1.070  SD    0.612   0.275  -3.459   1.000   0.046	5.61948
SRM		pit     yaw     pos     side    butt UL    0.891   1.125   0.950  -0.077   0.984  UR    0.934  -0.875   0.987  -0.011  -0.933  LR   -1.066  -1.020   1.050   0.010   1.084  LL   -1.109   0.980   1.013  -0.056  -0.999  SD    0.257  -0.021   0.304   1.000   0.006	4.0291
ITMX		pit     yaw     pos     side    butt UL    0.436   1.035   1.042  -0.068   0.728  UR    0.855  -0.965   1.137  -0.211  -0.969  LR   -1.145  -1.228   0.958  -0.263   1.224  LL   -1.564   0.772   0.863  -0.120  -1.079  SD   -0.522  -0.763   2.495   1.000  -0.156	4.55925
ITMY		pit     yaw     pos     side    butt UL    1.375   0.095   1.245  -0.058   0.989  UR   -0.411   1.778   0.975  -0.022  -1.065  LR   -2.000  -0.222   0.755   0.006   1.001  LL   -0.214  -1.905   1.025  -0.030  -0.945  SD    0.011  -0.686   0.804   1.000   0.240	4.14139
ETMX		pit     yaw     pos     side    butt UL    0.714   0.191   1.640   0.404   1.052  UR    0.197  -1.809   1.758  -0.120  -1.133  LR   -1.803  -1.889   0.360  -0.109   0.913  LL   -1.286   0.111   0.242   0.415  -0.902  SD    1.823  -3.738  -0.714   1.000  -0.130	5.19482
ETMY		pit     yaw     pos     side    butt UL    1.104   0.384   1.417   0.351   1.013  UR   -0.287  -1.501   1.310  -0.074  -1.032  LR   -2.000   0.115   0.583  -0.045   0.777  LL   -0.609   2.000   0.690   0.380  -1.179  SD    0.043  -0.742  -0.941   1.000   0.338	3.57032

Jenne, Anamaria

We aligned the ETMX OSEMs and ran into this issue. Looking at the SENSOR_SIDE channel, we pulled out the OSEM and determined that the open light voltage is 874 counts, so we centered it around 440 as well as we could. This is same channel as its slow counterpart SDSEN_OUTPUT (grey number immediately to the right on SUS medms).

ALL optics (including MC) were kicked and left free swinging at:

997689421

The "opticshutdown" script was also run, which should turn the watchdogs back on in 5 hours (at 6am).

Kiwamu and Steve, from yesterday

PRM and BS oplev paths were relaid after setting 1/2 OSEM voltages. The incident beam on suspended optics are centered  within  ~ +- 2 mm

I noticed many unvected ss screws are used on the big Al table tops. The SS 1/4-20 screws

 used on the optical tables in vacuum MUST be VENTED!

Also, please use  SS clamps. Replace aluminum ones when you can. We have plenty baked ones.

Most of the suspension look ok, with "badness" levels between 4 and 5.  I'm just posting the ones that look slightly less ideal below.

• PRM, SRM, and BS in particular show a lot of little peaks that look like some sort of intermodulations.
• ITMY has a lot of elements with imaginary components
• The ETMY POS and SIDE modes are *very* close together, which is severely adversely affecting the diagonalization

PRM		pit     yaw     pos     side    butt UL    0.466   1.420   1.795  -0.322   0.866   UR    1.383  -0.580   0.516  -0.046  -0.861   LR   -0.617  -0.978   0.205   0.011   0.867   LL   -1.534   1.022   1.484  -0.265  -1.407   SD    0.846  -0.632  -0.651   1.000   0.555	5.62863
SRM		pit     yaw     pos     side    butt UL    0.783   1.046   1.115  -0.149   1.029  UR    1.042  -0.954   1.109  -0.060  -1.051  LR   -0.958  -0.926   0.885  -0.035   0.856  LL   -1.217   1.074   0.891  -0.125  -1.063  SD    0.242   0.052   1.544   1.000   0.029	4.0198
BS		pit     yaw     pos     side    butt UL    1.536   0.714   0.371   0.283   1.042   UR    0.225  -1.286   1.715  -0.084  -0.927   LR   -1.775  -0.286   1.629  -0.117   0.960   LL   -0.464   1.714   0.285   0.250  -1.070   SD    0.705   0.299  -3.239   1.000   0.023	5.5501
ITMY		pit     yaw     pos     side    butt UL    1.335   0.209   1.232  -0.071   0.976   UR   -0.537   1.732   0.940  -0.025  -1.068   LR   -2.000  -0.268   0.768   0.004   1.046   LL   -0.129  -1.791   1.060  -0.043  -0.911   SD   -0.069  -0.885   1.196   1.000   0.239	4.28384
ETMY		pit     yaw     pos     side    butt UL    1.103   0.286   1.194  -0.039   0.994  UR   -0.196  -1.643  -0.806  -0.466  -1.113  LR   -2.000   0.071  -0.373  -0.209   0.744  LL   -0.701   2.000   1.627   0.217  -1.149  SD    0.105  -1.007   3.893   1.000   0.290	9.25346

damped sus at atm1 and freeswingging sus at atm2

I ran "freeswing all" at Fri Aug 19 01:09:28 PDT 2011 (997776583)  and "opticshutdown"  as well.

Free swingging OSEM sensors LL at atm

excited all the optics ---

Tue Aug 23 01:08:00 PDT 2011
998122096

SUS update before closing up:

• MC1, MC2, ITMX look good
• MC3, PRM look ok
• SRM pos and side peaks are too close together to distinguish, so the matrix is not diagnalizable.  I think with more data it should be ok, though.
• all ITMY elements have imaginary components
• ITMY, ETMX, ETMY appear to have modest that swapped position:
  • ITMY: pit/yaw
  • ETMX: yaw/side
  • ETMY: pos/side
• MC3, ETMX, ETMY have some very large/small elements

Not particularly good.  We're going to work on ETMY at least, since that one is clearly bad.

OPTIC		M	cond(B)
MC1		pit     yaw     pos     side    butt UL    0.733   1.198   1.168   0.050   1.057  UR    1.165  -0.802   0.896   0.015  -0.925  LR   -0.835  -1.278   0.832  -0.002   0.954  LL   -1.267   0.722   1.104   0.032  -1.064  SD    0.115   0.153  -0.436   1.000  -0.044	4.02107
MC2		pit     yaw     pos     side    butt UL    1.051   0.765   1.027   0.128   0.952   UR    0.641  -1.235   1.089  -0.089  -0.942   LR   -1.359  -0.677   0.973  -0.097   1.011   LL   -0.949   1.323   0.911   0.121  -1.096   SD   -0.091  -0.147  -0.792   1.000  -0.066	4.02254
MC3		pit     yaw     pos     side    butt UL    1.589   0.353   1.148   0.170   1.099   UR    0.039  -1.647   1.145   0.207  -1.010   LR   -1.961  -0.000   0.852   0.113   0.896   LL   -0.411   2.000   0.855   0.076  -0.994   SD   -0.418   0.396  -1.624   1.000   0.019	3.60876
PRM		pit     yaw     pos     side    butt UL    0.532   1.424   1.808  -0.334   0.839   UR    1.355  -0.576   0.546  -0.052  -0.890   LR   -0.645  -0.979   0.192   0.015   0.881   LL   -1.468   1.021   1.454  -0.267  -1.391   SD    0.679  -0.546  -0.674   1.000   0.590	5.54281
BS		pit     yaw     pos     side    butt UL    1.596   0.666   0.416   0.277   1.037   UR    0.201  -1.334   1.679  -0.047  -0.934   LR   -1.799  -0.203   1.584  -0.077   0.952   LL   -0.404   1.797   0.321   0.247  -1.077   SD    0.711   0.301  -3.397   1.000   0.034	5.46234
SRM	NA	NA	NA
ITMX		pit     yaw     pos     side    butt UL    0.458   1.025   1.060  -0.065   0.753   UR    0.849  -0.975   1.152  -0.199  -0.978   LR   -1.151  -1.245   0.940  -0.243   1.217   LL   -1.542   0.755   0.848  -0.109  -1.052   SD   -0.501  -0.719   2.278   1.000  -0.153	4.4212
ITMY		pit     yaw     pos     side    butt UL    0.164   1.320   1.218  -0.086   0.963   UR    1.748  -0.497   0.889  -0.034  -1.043   LR   -0.252  -2.000   0.782  -0.005   1.066   LL   -1.836  -0.183   1.111  -0.058  -0.929   SD   -0.961  -0.194   1.385   1.000   0.239	4.33051
ETMX		pit     yaw     pos     side    butt UL    0.623   1.552   1.596  -0.033   1.027   UR    0.194  -0.448   1.841   0.491  -1.170   LR   -1.806  -0.478   0.404   0.520   0.943   LL   -1.377   1.522   0.159  -0.005  -0.860   SD    1.425   3.638  -0.762   1.000  -0.132	4.89418
ETMY		pit     yaw     pos     side    butt UL    0.856   0.007   1.799   0.241   1.005   UR   -0.082  -1.914  -0.201  -0.352  -1.128   LR   -2.000   0.079  -0.104  -0.162   0.748   LL   -1.063   2.000   1.896   0.432  -1.119   SD   -0.491  -1.546   2.926   1.000   0.169	9.11516

excited all the optics. (with ITMY WTF OFF)

Tue Aug 23 11:52:52 PDT 2011
998160788

Before lunch we took a closer look at two of the suspensions that were most problematic: ITMY and ETMY.  Over lunch we took new free swinging data.  Results below:

• For ITMY we discovered that the whitening on the UL sensor was not switching.  This was causing the UL sensor to have a different response, with a steeper roll of, which was causing all of the transfer function estimates to the other sensors to have large imaginary components.   We took new free swing data with all of the whitening turned OFF.  The result is a much improved matrix and diagnalization.  The input matrix elements are mostly the same, but the coupling is basically gone.  We'll fix the whitening after the pump down.

ITMY

pit     yaw     pos     side    butt UL    0.157   1.311   1.213  -0.090   0.956  UR    1.749  -0.490   0.886  -0.038  -1.042  LR   -0.251  -2.000   0.787  -0.007   1.066  LL   -1.843  -0.199   1.114  -0.059  -0.936  SD   -0.973  -0.205   1.428   1.000   0.239

4.34779

• ETMY has a very problematic SIDE OSEM.  The magnet does not line up with the OSEM axis, and since there is no lateral adjustment in the side OSEMs, there's not much we can do about this.  We're using aluminum foil to wedge the OSEM over as far as possible, but it's not quite enough.  With the OSEM plates horizontal there is a lot of POS->SIDE coupling.  With the OSEM plates vertical, the magnetic sits a little too close to the rear face, which can cause the magnet to get stuck to the LED plate.  We're trying to decide where to leave it now, but the new diagnalization with the OSEM plates vertical is definitely better: 

ETMX

pit     yaw     pos     side    butt UL   -0.138   1.224   1.463  -0.086   0.944   UR    0.867  -0.776   1.501  -0.072  -1.051   LR   -0.995  -0.896   0.537  -0.045   0.754   LL   -2.000   1.104   0.499  -0.059  -1.251   SD    0.011   0.220   1.917   1.000   0.224

4.42482

Excited ETMY

Tue Aug 23 17:20:45 PDT 2011
998180460

 

In preparation for tomorrow's drag wiping and door closing, I have clamped ITMX, ITMY, and ETMX with their earthquake stops and moved the suspension cages to the door-edge of their respective tables.  They will remain clamped through drag wiping.

ETMY was left free-swinging, so we will clamp and move it directly prior to drag wiping tomorrow morning.

By looking at a longer data stretch for the SRM (6 hours instead of just one), we were able to get enough extra resolution to make fits to the very close POS and SIDE peaks.  This allowed us to do the matrix inversion.  The result is that SRM looks pretty good, and agrees with what was measured previously:

SRM

pit     yaw     pos     side    butt UL    0.869   0.975   1.140  -0.253   1.085   UR    1.028  -1.025   1.083  -0.128  -1.063   LR   -0.972  -0.993   0.860  -0.080   0.834   LL   -1.131   1.007   0.917  -0.205  -1.018   SD    0.106   0.064   3.188   1.000  -0.011

4.24889

We ran one more free swing test on ETMY last night, after the last bit of tweaking on the SIDE OSEM.  It now looks pretty good:

ETMY

pit     yaw     pos     side    butt UL   -0.323   1.274   1.459  -0.019   0.932  UR    1.013  -0.726   1.410  -0.050  -1.099  LR   -0.664  -1.353   0.541  -0.036   0.750  LL   -2.000   0.647   0.590  -0.004  -1.219  SD    0.021  -0.035   1.174   1.000   0.137

4.23371

 So I declare: WE'RE NOW READY TO CLOSE UP.

We've closed up ETMX:

• the optic was drag wiped
• the suspension tower was put back in place
• earthquake stops were backed off the appropriate number of turns, and de-ionized
• chamber door was put on

ITMX was drag wiped, and the suspension was put back into place.  However, after removing all of the earthquake stops we found that the suspension was hanging in a very strange way.

The optic appears to heavily pitched forward in the suspension.  All of the rear face magnets are high in their OSEMs, while the SIDE OSEM appears fine.  When first inspected, some of the magnets appeared to be stuck to their top OSEM plates, which was definitely causing it to pitch forward severely.  After gently touching the top of the optic I could get the magnets to sit in a more reasonable position in the OSEMs.  However, they still seem to be sitting a little high.  All of the PDMon values are also too low:

Taking a free swing measurement now.

ITMX: 998245556

ETMX, ETMY: 998248032

I broke the UL magnet on ITMX

The ITMX tower was shipped into the Bob's clean room to put the magnet back on.

 Since we found that all the magnets were relatively high (#5296) in the shadow sensors, we decided to slide the OSEM holder bar upward.

During the work, I haven't made the OSEMs far enough from the magnets.

So the magnets and OSEMs touched as I moved the holder.

Then the UL magnets were broken off and fell into the UL coil.

 Repair work is delayed.  I need the "pickle pickers" that hold the magnet+dumbbell in the gluing fixture, for gluing them to the optic.  Here at the 40m we have a full set of SOS gluing supplies, except for pickle pickers.  We had borrowed Betsy's from Hanford for about a year, but a few months ago I returned all of the supplies we had borrowed.  Betsy said she would find them in her lab, and overnight them to us.  Since the problem occurred so late in the day, they won't get shipped until tomorrow (Thursday), and won't arrive until Friday.

I also can't find our magnet-to-dumbbell gluing fixture, so I asked her to send us her one of those, as well. 

I have 2 options for fixing ITMX.  I'll write down the pros and cons for each, and we can make a decision over the next ~36 hours.

OPTIONS:

(#1) Remove dumbbell from optic.  Reglue magnet to dumbbell. Reglue magnet+dumbbell to optic.

(#2) Carefully clean dumbbell and magnet, without breaking dumbbell off of optic.  Glue magnet to dumbbell.

PROS:

(#1) Guarantee that magnet and dumbbell are axially aligned.

(#2) Takes only 1 day of glue curing time.

CONS:

(#1) Takes 2 days of glue curing time. (one for magnet to dumbbell, one for set to optic.)

(#2) Could have slight mismatch in axis of dumbbell and magnet.  Could accidentally drop a bit of acetone onto dumbbell-to-optic glue, which forces us into option 1, since this might destroy the integrity of the glue joint (this would take only the 2 days already required for option 1, it wouldn't force us to take 2+1=3 days).

 jamie, jenne, kiwamu, suresh, steve

ETMY and ITMY were treated the same way as ETMX. The BS chamber was closed with heavy vac door yesterday also. The IOO access connector's inner jamnuts are torqued to 45 ft/lbs as all vac door bolts.

The vac envelope is ready for pumpdown condition, except ITMX chamber with light atm door cover.

Jenne will summeries the condition of dust on the  TMs before and after the drag wipes.

As we have seen in the past, both of the ITMs were more dusty than the ETMs, presumably because we have the vertex open much more often than the ends.  Kiwamu and I wiped all of the optics until we could no longer see any dust particles within a ~1.5 inch diameter area around the center. 

Since we have ITMX out for magnet gluing, I'll probably drag wipe both front and back surfaces before putting it back in the suspension cage.  All of the optics have clear dust on the AR surfaces, but we can't get to that surface while the optics are suspended.  For the ETMs this isn't too big of a deal, but it does concern me a bit for the ITMs and other transmissive optics we have.  I don't think it's bad enough yet though to warrant removing optics from suspensions just to wipe them.

Dmass just reminded me that the usual procedure is to bake the optics after the last gluing, before putting them into the chambers.  Does anyone have opinions on this? 

On the one hand, it's probably safer to do a vacuum bake, just to be sure.  On the other hand, even if we could use one of the ovens immediately, it's a 48 hour bake, plus cool down time.  But they're working on aLIGO cables, and might not have an oven for us for a while.  Thoughts?

I think we should follow the established procedure in full, even though it will cost us a few more days.  I dont think we should consider the vacuum bake as something "optional".  If the glue has any volatile components they could be deposited on the optic resulting in a change in the coating and consequently optical loss in the arm cavity.

 Follow full procedure for full strength, minimum risk