Foton doesn't correctly display the LSC filter bank file : C1LSC.txt.
Foton tells a lie that they all are empty.
The file itself looks fine to me i.e. I can find correct filters in text format.
Looks like someone (maybe Joe and Jenne ?) updated the file. I am not sure if this is the reason or not.
allegra:chans>ls -al | grep LSC
-rw-r--r-- 1 controls controls 20659 May 5 11:46 C1LSC.txt
NEEDS TO BE FIXED SOON
See my updated elog 4636 for what Joe and I did this morning, and what a possible problem is (making the LSC model into a sub-model).
I put the ETMY trans QPD in.
The ETMY trans beam was already going toward the TRY DC PD, and a CCD camera. I put a beam splitter in that beam (reducing the power to TRY and the CCD by 50%), and sent my picked-off beam to the ETMY QPD. Since there is a lens in this path to focus the beam onto TRY and the camera, I put the QPD ~the same distance from the lens as the camera. Due to space requirements (because of all the green stuff on the table now), I had to put a Y1 turning mirror between the beam splitter and the QPD. The beam is aligned onto the PD, although the signal isn't super strong. When the PD is blocked, the sum is ~(-92 counts). When the beam is on the PD, the sum is ~(-78 counts).
I didn't notice it the other day when I was working on putting in the trans QPD, but do we need to switch the mirror mount for the first turning mirror of the IR trans beam, which the green transmits through to go into the cavity? It seems like we've set ourselves up for potential clipping.
Just for a record. This is the latest picture of the ETMY optical bench.
I will upload this picture on the wiki after the wiki gets up.
Aka, from a hotel in Pisa.
I am in the process of calibrating AS55's shot noise, and I noticed that the AS55 PD input to the demod board was only finger-tight. I then checked all of the other SMA connections in the set of RF PD demod boards, and found several more that were loose, including all of the REFL55 connections. This is no good!!!! RF connections need to be tightened! I went through and tightened all of the offending connections with my personal Snap-on SMA wrench.
The noise graphs relating total noise of the Seismometer circuit (GURALP stuff) to the LIGO seismic noise curve have been completed started.
What Larisa meant to post (I'm sure) is something more like this (sorry it's a little squished...I put too many words in the legend):
I've only included the 2 noise contributions from the LISO model that seem to dominate the sum noise. The plot gets a little crazy if you include all of the non-important sources.
So, what's the point??
First, the new box design doesn't have any crazy-special op-amps in it, so the noise of the new box is probably comparable to the old box. So, if that's true, the old box may not have been limiting the differential seismic noise. This definitely needs to be checked out. I'll make a quickie LISO model of the old Guralp breakout box, to see what its noise actually looks like, according to LISO. If it wasn't ever the breakout box that was limiting us, what the heck was it??
Second, the current box design seems to be better than the Guralp Spec sheet noise by ~a factor of 10. It would be nice if that number were more like a factor of 100. Or at least 30. So some work needs to be done to find a lower-noise op amp for the voltage buffer (the first op amp in the circuit).
Since Larisa is now starting her SURF project with Tara and Mingyuan, I'll look into improving the design of this box by a factor of 3 or 10.
Then I'll need to make a mock-up of it, and test it out.
If successful, then I'll draw it up in Altium and have it made. Recall that there should be 2 outputs per seismometer channel, one with high gain, one with low gain. Then 3 seismometer channels per seismometer (X, Y, Z), and perhaps multiple seismometer inputs per box. So lots and lots of stuff all in the same box. It's going to be pretty cool.
I would like to announce my confusion with regard to the MICH noise budget, in hopes that someone else has some inspiration.
If you tilt your head sideways, you will notice that in this plot (totally uncalibrated, as yet), the BLACK trace, which is my white-light measurement of the AS55 shot noise is above the AS55Q noise when the Michelson is locked (true only at low frequency). You will also notice that the same appears to be true for the Whitening Filter + Antialiasing Filter + ADC noise (GRAY trace). Since Black, Gray, Pink and Green should all have the same calibration factor (a constant), calibrating the plot will not change this. Brown and Blue are the MICH_OUT (aka MICH_CTRL) for dark and bright fringes, respectively.
I measure 58mV at the DC out of the AS55 PD when the Michelson is locked on the bright fringe. This (assuming DC transimpedance of 50ohms) gives 1.16mA of DC photo current.
So. What is going on here? Am I totally confused??
In other news, assuming (which I'm not 100% confident about right now) that these traces are vaguely correct, the Michelson is limited by shot noise above ~20Hz. This is...good? We want to be shot noise limited. Do we want to be limited at such a low frequency?
(Also, yes I can calibrate the plot to m/rtHz, but no, I won't tonight because something is funny with my calibration for the free running noise and I'll fix it tomorrow.)
After talking with Steve, I had a look at the PEM's AA board, to see what the problem was.
Steve said the symptom he had noticed was that the Kepco power supplies which supply the +\- 5 V to the AA board were railing at their current limits as soon as he plugged the board in. Also, he smelled smoke.
I started with the power supplies, and saw that the 2 individual supplies each had a dV=5V, and that the one labeled +5V had the red wire on the + output of the power supply, and the black wire on the - output. The supply labeled -5V had the orange wire on the -output of the power suppy, and the black wire on the + output. Normally, you would expect that the 2 black wires are also connected together, and perhaps also to ground. But at least together, so that they share a common voltage, and you get +\- 5V. However these 2 power supplies are not connected together at all.
This implies that the connection must be made on the AA boards, which I found to be true. It seems a little weird to me to have that common ground set at the board, and not at the power supplies, but whatever. That's how it is.
The problem I found is this: The keyed connectors were made backward, so that if you put them in "correctly" according to the key, you end up shorting the +5V to the -5V, and the 2 black wires are not connected together. You have to put the keyed connectors in *backwards* in order to get the correct wires to the correct pins on the board. See the attached pdf figure.
Since these are internal board connections, and they should not ever be changed now that Steve has put in the adapter thing for the SCSI cable, I'm just leaving them as-is. Steve is going to write in huge letters in sharpie on the board how they're meant to be connected, although since this problem wasn't caught for many many years, maybe it won't ever be an issue again. Also, we're going to move over to the new Cymac system soon-ish. However, whomever made the power cable connector from the box to the board for this AA board was lazy and dumb.
After putting the connectors on the way they needed to be, Steve and I powered up the board, hooked up the SCSI cable in the back, and put a constant voltage (~1.3VDC battery) across various different channels, and confirmed that we could see this voltage offset in Dataviewer. (Kiwamu is hoarding both of our SRS function generators, so we couldn't put in a low freq sine wave like I normally would). Everything looked okie dokie, so I'll check the regular PEM channels tomorrow.
Steve will re-install the board in the rack in the morning.
I found the PMC unlocked. Koji noticed that the FSS Slow Actuator Adjust was railed at the positive end of the slider. I set it close to zero, and relocked the PMC. The FSS slow loop servo is doing its thing, and the PMC and MC are now locked.
I have measured / calculated the latest MICH noise budget. It doesn't really look all that stellar.
As you can see, we are nowhere near being shot noise limited, since there's a huge discrepancy between all of the measured spectra and the teal Shot Noise line.
One possible suspect is that the analog whitening filters weren't on when I took my measurements. I didn't actually check to ensure that they were on, so they might not have been. Right now we're limited by electronics and other boring noises, so I need to make sure we're limited by the noise of the diode itself (we don't have enough light in the IFO to actually be shot noise limited since that takes 2.5mA for AS55 and I only have 1.1mA, but we should be ~within a factor of 2ish).
(1) DC magnetic force is imbalanced, and we found that one pair has a stronger DC force than others. This should
be able to solved simply by replacing them with magnets have comparable strength to others.
I don't know if this would work, but it might be worth a try:
You've achieved single levitation before, with fairly good stability. Can you try taking each magnet + coil and finding the DC coil current required to hold a mass at a given position? If you can hold the same mass at the same place with all the different magnets+coils, then you're exerting the same force against gravity, so your DC forces are balanced.
While closing up the whitening shop for the night, I noticed that the ITMX whitening state (Whitening "On") is opposite that of all other suspensions (they all have Whitening "Off"). I don't know which way is correct, but I assume they should all be the same. Once all the whitening and BO testing is done, we should make sure that they're all the way we want them to be.
Also, Koji and I are leaving ETMX free swinging. That's the way we found it, presumably from Jamie's BO testing at the end station today. We don't know what the optic's story is, so we're leaving it the way we found it. Jamie (or whomever left it free swinging), can you please restore it when it is okay to do so? Thanks!
I have fit all of the LSC whitening filters using vectfit4.m
All the data is in my folder ..../users/jenne/LSC_WhiteningTest_29June2011/
The zpk info is saved with each plot of the fit. The pdfs are kind of huge to stitch together (or rather my computer doesn't want to do it), so I'll just post a representative one for now.
During the daytime either tomorrow or Friday I'll adjust the actual dewhitening filters to match the measured zpk values.
I made a handy-dandy table showing the zpk values for each whitening filter in the wiki: New whitening filter page
Next on the whitening filter to-do list: actually put these values into the dewhitening filters in foton.
It was unlocked since ~4:30am. No idea why. It's relocked so I can try round N of measuring the PRC length.
There's too much tromping around, so I'm not going to actually measure PRC length right now, but I did set some channels to be acquired (POPDC, POXDC, POYDC) in addition to ASDC which was already acquired, so that I can look at the resonance fringes when I sweep the ABSL laser (hopefully later tonight....)
We decided to take on the deceptively easy-sounding task of checking that the LSC whitening switching was happening as anticipated. We hoped to discover that when we clicked the "unwhitening" switches in FM1 of the LSC PDs, we would see the analog whitening turn on and off for the matching channel. That is what is supposed to happen.
Tragically, it is instead one big giant crazy disaster of a mess.
What we did:
Made a 24tapus (octopus like last time, except more...), with a 50kOhm resistor as our white noise source (instead of using a DAC channel and AWG).
We plugged our 24tapus into the 3 of 4 whitening boards on the LSC rack that are currently in use. One of the boards just has 8 terminators on the input, so we left that one alone for now.
We put the whitening gains to 0dB so that all the channels looked the same.
We looked at the PD _IN1 channels in DTT, and monitored which signals had whitening switching when we clicked the "unwhitening" buttons on the PD filter banks.
So far, we can find no rhyme or reason as to why some of the channels work (click unwhite on that PD, see that signal have whitening switching), and others don't. Some channels we just can't get to switch no matter what, others are just mis-mapped. There is no discernible pattern.
What we think (so far) is going on:
All of the cables from the PD demod boards are going to the Whitening board inputs, exactly as in Suresh's Diagram. The only difference is that Refl33, AS165 and Refl165 demod boards don't exist in the rack at this time.
The Whitening and AA boards in Suresh's Diagram labeled 0-7 are connected to Binary Output channels 0-7. This is a good thing.
The Whitening and AA boards in the diagram labeled 8-15 are connected to Binary Output channels 24-31. This is not so awesome.
This is all we are confident about at this time.
We are hoping that Ben has a secret stash (or can tell us who would) of LSC rack wiring diagrams. We would like to find out, without the pain of tracing wires and cables by hand, how the Binary I/O information gets through the cross-connect on the LSC rack up to the whitening boards.
We are leaving the 24tapus in place for now, so that we can carry on tomorrow, either with a wiring diagram in hand, or carefully tracing cables.
We had another look at the MICH noise budget tonight. Rana has verified that my techniques / math aren't too ridiculous.
In the first attachment, you'll notice that the MICH noise is waay above the shot noise of 1mW on the beam splitter. We don't know why. One problem is that the modulation depth of the 55MHz is too low by ~a factor of 10. Kiwamu and his magical resonant circuit are working on fixing this. This will not, however, fix the huge discrepancy here. More investigation and meditation is required! For this measurement, the whitening gain of AS55 was set to 42dB for both I and Q.
In the 2nd attachment, the PSL shutter is closed, so all of these are dark measurements of AS55. (The input matrix on the LSC screen is AS55Q * 1 -> MICH_IN1, so they're the same). All we've done is change the whitening gain before the ADC. For 0dB and 9dB, you can see that the low freq noise didn't change - here we're still limited by the ADC noise. With 21dB and 42dB we're clear of the ADC, so either is fine. Unfortunately, the high freq stuff when the loop is on matches up with the high freq part of the dark noise, so that's part of the problem....
Because I'm too lazy to write a cohenrent elog right now, here's my notes that I wrote while working tonight:
Elog notes, 27July2011
Aligned Xarm, just to check on it. Had to flip sign of TRX in DCPD filter bank (to gain of -1) to make the signal positive.
Restored Yarm, see some slight flashing, but no lock yet.
Adjusted phase rotation of AS55 from 56.5deg to 60deg, just by-eye trying to maximize AS55I, my arm error signal. AS55I goes from ~ -40 to +60 counts
Tried fitzing with Yarm gain, flipping sign, incr gain. No real change in signals, or flashing.
Incr. ETMY oplev gains to -0.4 from -0.2
Engaged ELP35's on Pit and Yaw, to be more similar to other optics. However, right now all of the optics have different things in their filter banks. Why??
Arm is flashing pretty reliably now, but still not locking. The trigger threshold is always satisfied, so that's not it.
The hazardous waste people are moving chemicals around outside our door, and have roped off our regular front door.
Please go around, and use the control room door to enter and exit. It is currently unlocked, although I'll lock up when I leave for LIGOX.
I found PRM watchdog tripped. It's all better now.
So far, this is just preliminary, because I haven't done full error analysis to determine the error on my measurements. That will hopefully be done by tomorrow afternoon (so before we start taking off doors).
I find that the length of the Xarm is: 37.5918 meters.
I find that the length of the Yarm is: 37.5425 meters.
I used the mass-kicking technique, as summarized by Kiwamu, and fully described by Alberto. More words / description to follow with the full error analysis.
While Kiwamu was finalizing the X green alignment, I started to prepare to remove the ETMY door, and begin checking out its OSEMs, etc, so we could start moving it to it's new place, and figure out why it's been wonky for a while. I ran the particle counter, and we have a factor of ~5 more particles than normal. Kiwamu and I agreed not to open ETMY. Since we had briefly opened the IOO and Output Optics chambers to check the X green's position on the PSL table, we immediately shut those doors. They were probably open for ~15 minutes or so. (Yes Steve, we should have checked before opening any doors, but at least we remembered to check at all, and the doors were only open for a few minutes rather than for a few hours.)
I attach a 24hrs trend of the particle counts, for reference. It looks like it's been a little high for a while, but today it's really dirty in the air.
The ETMY suspension tower is in a good place.
Kiwamu will work on the green alignment over the weekend. Assuming everything works out, we'll try the same procedure on ETMY on Monday.
You meant ETMX, right? ETMY still hasn't been touched.
KI : sorry, I meant ETMX. I fixed the entry.
- Jenne will make a better kick/free-swing test later.
02:27am, ran the new freeswinging-ifo.csh script. It's just a copy of freeswinging-all.csh, but it doesn't include the MC mirrors, since Suresh and Kiwamu are still working.
Now we have copies of the script for -all, -mc, -ifo to cover the various sections of the suspended interferometer.
ETMY is now in its new nominal position, according to the rails that Kiwamu put in the other day. OSEM voltages are all centered, and the magnets looked pretty well centered in the OSEM bores. We're taking data for some free swinging spectra, to check the decoupling.
Next up: Align Y-green to the arm, then move on to fixing the other optics that Jamie pointed out.
[Jenne, with ample supervision by Kiwamu and Suresh]
Y-green was aligned, and is now flashing. The ETMY trans camera was very helpful for this alignment. I didn't end up needing to use a foil aperture.
Kiwamu and Suresh had just closed up the IOO doors, so we don't know yet where it's hitting on the PSL table (if the beam is making it that far). Tomorrow we'll look at ITMY to see if the green beam is centered there, and if it's coming out to the PSL table.
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
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
Excited all optics
Fri Aug 12 17:38:53 PDT 2011
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.
like the subject says...
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.
I'm no longer convinced that ETMY is healthy. I can't fit the peaks to get the input matrix.
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.
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
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
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
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
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
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
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
+ Rotate the SRM tower to get the SRMI fringes on the AS CCD camera.
=> This is because the required amount of the YAW correction on SRM is currently beyond the range of the DC bias.
Kiwamu aligned things for me, and I rotated the SRM tower so that the reflected beam was pretty much totally overlapping the incident beam. The SRC was aligned to make sure things were good. Now the DC bias for SRM Yaw is ~1.4, so we're totally good.
To rotate SRM, Jamie had the idea of using 2 screws so I could push the tower on one side, and back off the screw an equal amount on the other side and push the tower to be touching both screws again, to ensure that I was rotating about the center of the tower and wasn't introducing any Pos action.
While I was at it, I also moved the OSEM connector tower back to its normal place on the table, so it's not in the way of oplev beams. It had been moved previously to accommodate ITMY near the door.
We will pump down the chambers on Thursday Friday morning.
All hands on deck at 9am Thursday for drag wiping and doors. We'll do the 5 doors first (including drag wiping), then put on the access connector last. Steve will then begin pumping early Friday morning.
While waiting for the IFO team to align things (there were already ~5 people working on a ~1 person job...), I got all of our supplies prepped for drag wiping in the morning.
The syringes are still on the flow bench down the Xarm. I put fresh alcohol from unopened spectrometer-grade bottles into our alcohol drag wiping bottles.
The ITMs already had rails for marking their position in place from the last time we drag wiped. I placed marker-rails for both ETMs.
After the IFO was aligned in air one final time, we tapped on a few OSEMs until we were happy with all of the centering of all of the optics' OSEMs. All are within 0.05 of their halfway values, with the exception of one each on MC1 and MC3, one of which is within 0.06, and the other 0.08. Because of the realignment pain of dealing with MC OSEMs, we elected to leave these alone. Also, since we obviously didn't open the MC2 tank, we don't know how they are, although the numbers look reasonable.
Also, we took photos (to be posted on Picasa in a day or two) of all the main IFO magnet-in-OSEM centering, as best we could. SRM, BS, PRM all caused trouble, due to their tight optical layouts. We got what we could. Various people have been looking at these for the past 2 weeks, and I think they're all fine, even if we didn't get stellar photos.
We are now prepared for pumping. For real this time.
We will begin drag wiping and putting on doors at 9am tomorrow (Tuesday).
We need to get started on time so that we can finish at least the 4 test masses before lunch (if possible).
We will have a ~2 hour break for LIGOX + Valera's talk.
I propose the following teams:
(Team 1: 2 people, one clean, one dirty) Open light doors, clamp EQ stops, move optic close to door. ETMX, ITMX, ITMY, ETMY
(Team 2: K&J) Drag wipe optic, and put back against rails. Follow Team 1 around.
(Team 3 = Team 1, redux: 2 people, one clean, one dirty) Put earthquake stops at correct 2mm distance. Follow Team 2 around.
(Team 4: 3 people, Steve + 2) Close doors. Follow Team 3 around.
Later, we'll do BS door and Access Connector. BS, SRM, PRM already have the EQ stops at proper distances.
[Steve, Bob, Jamie, Kiwamu, Valera, Jenne]
The access connector is now in place, in preparation for pump-down. Tomorrow (hopefully) we will do all the other doors.
The ITMX tower was shipped into the Bob's clean room to put the magnet back on.
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.
(#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.
(#1) Guarantee that magnet and dumbbell are axially aligned.
(#2) Takes only 1 day of glue curing time.
(#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).
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?
Jamie and Shuresh moved in Jenne's 11 drawers cabinet and relocated old note book boxes on the inside of the vac tube.
Barring other chores for next Wednesday, we're going to spend Wednesday afternoon populating the new cabinet with all of the optics hardware: posts, forks, dogs, everything! It's going to be so organized and awesome!!
As I feared, since I couldn't see the magnet-to-dumbbell joint from all angles, they ended up being off by ~1/3 of a magnet diameter.
Because I don't want to deal with finding another failed glue joint tomorrow, I removed the magnet and dumbbell from the optic, and broke the manget off of the dumbbell. As with yesterday, I kept track of which end of the magnet had been glued to the dumbbell.
I got a new dumbbell, removed all the glue from the magnet, and reglued them together, in the fixture that ensures they are well aligned.
Tomorrow I will come in and glue the magnet dumbbell assembly to the ITM.
Tomorrow afternoon I'll remove the optic from the fixture, and put it in the oven.
[Kiwamu, Manuel, Jenne]
The new optics storage drawers have been populated with optics. Each drawer is labelled. Harsh punishments will be inflicted on anyone found disobeying the new scheme.
[Jenne, Katrin, Jamie]
I'm a bad kid, and forgot to elog my Friday morning work...
Bob gave me back ITMX after a 48hour bake at 80C + clean RGA scan Friday morning after coffee and doughnuts. Katrin helped me put it back in the suspension wire.
While I was leveling the optic (making sure the scribe lines on each side of the optic are at the same height off the table), Katrin cut some new viton for replacement EQ stops. The optic was missing one lower earthquake stop (the one that Jamie noticed last week), and somehow one other rubber piece came out of the EQ stop on another lower screw while we were re-suspending the optic. We put the new stops in, and then checked the balance of the test mass.
The oplev is still the HeNe laser that is leveled to the level optical table in the cleanroom. The lever arm is ~1.5 meters, and over that distance the reflected beam was pointed "up" in pitch by ~1.5mm, which is less than one beam diameter of the HeNe. This is well within our ability to correct using the OSEMs.
We then locked the test mass, and installed it in the chamber. I approximately did the half-voltage centering of the OSEMs, leaving the fine-tuning to Kiwamu for after lunch.
These are the things that I can think of that we need to do before we can close up:
* Take a close look at both ITMs' OSEMs, and ensure that the magnets aren't too close to either plate in the OSEMs. Both have had funny business over the past week.
* Do a free swinging test on both ITMs. (ITMY may not need it, if we haven't touched it since the last free swinging test, but it can't hurt to take the data)
* Confirm that POX is exiting the chamber.
* Is there anything else???
Our goal is to finish this work by tonight, so that we can close doors and start pumping tomorrow.
Tue Sep 6 17:48:02 PDT 2011
Kiwamu excited ITMY (which Suresh had already started). I just kicked ITMX:
Tue Sep 6 17:55:21 PDT 2011