ID |
Date |
Author |
Type |
Category |
Subject |
7575
|
Thu Oct 18 12:02:32 2012 |
Den | Update | IOO | MCL, WFS triggers |
Quote: |
I've redone the WFS triggers. I left the MCL trigger alone (for now....I'll come back to it).
The trigger was setup such that (a) it was totally unclear what was going on, by looking at the WFS screen. Koji and I spent some time confused before I remembered that Den did this work recently. Also, for some reason, the triggers were just plain thresholding, not a schmidt trigger, so any time the cavity flashed, the WFS came on. Since the cavity can flash before the mcdown script has a chance to turn off the WFS servos, the outputs of the WFS filters are trying to output thousands of counts, and the signal goes through any time the cavity flashes. Not so good.
|
Your schmitt trigger has 2 threshold values - min and max. Set thresholding value in my trigger to the max of your schmitt trigger and you get the same behavior for MC, triggers are not supposed to turn anything on in this realization as they do for locking with flashing. |
7574
|
Thu Oct 18 08:00:40 2012 |
jamie | Update | Computers | Re: Lots of new White :( |
Quote: |
Solved. The power code of c1iscaux was loose.
Has anyone worked around the back side of 1Y3?
I looked into the problem. I went around the channel lists for each slow machines and found the variables are supported by c1iscaux
controls@pianosa:/cvs/cds/caltech/target/c1iscaux 0$ cd /cvs/cds/caltech/target/c1iscaux
controls@pianosa:/cvs/cds/caltech/target/c1iscaux 0$ grep C1:IF *
C1IFO_STATE.db:grecord(ai,"C1:IFO-STATE")
It seemed that the machine was not responding to ping. I went to 1Y3 and found the crate was off. Actually this is not correct.
The key was on but the power was off. I looked at the back and found the power code was loose from its inlet.
Once the code was pushed in and the crate was keyed, the white boxes got back online.
Just in case I burtrestored these slow channels by the snapshot at 6:07am on Sunday.
|
I was working around 1Y2 and 1Y3 when I wired the DAC in the c1lsc IO chassis in 1Y3 to the tip-tilt electronics in 1Y2. I had to mess around in the back of 1Y3 to get it connected. I obviously did not intend to touch anything else, but it's certainly possible that I did. |
7573
|
Thu Oct 18 03:57:20 2012 |
Jenne | Update | Locking | Alignment is really bad?? |
The goal of the night was to lock the Y arm. (Since that didn't happen, I moved on to fixing the WFS since they were hurting the MC)
I used the power supplies at 1Y4 to steer PZT2, and watched the face of the black glass baffle at ETMY. (elog 7569 has notes re: camera work earlier) When I am nearly at the end of the PZT range (+140V on the analog power supply, which I think is yaw), I can see the beam spot near the edge of the baffle's aperture. Unfortunately, lower voltages move the spot away from the aperture, so I can't find the spot on the other side of the aperture and center it. Since the max voltage for the PZTs is +150, I don't want to go too much farther. I can't take a capture since the only working CCD I found is the one which won't talk to the Sensoray. We need some more cameras....they're already on Steve's list.
When the spot is a little closer to the center of the aperture than the edge of the aperture (so the full +150V!!), I don't see any beam coming out of AS....no beam out of the chamber at all, not just no beam on the camera. Crapstick. This is not good. I'm not really sure how we (I?) screwed up this thoroughly. Sigh. Whatever ghost REFL beam that Kiwamu and Koji found last week is still coming out of REFL.
Previous PZT voltages, before tonight's steering: +32V on analog power supply, +14.7 on digital. This is the place that the PRMI has been aligned to the past week or so.
Next, just to see what happens, I think I might install a camera looking at the back (output) side of the Faraday so that I can steer PRM until the reflected beam is going back through the Faraday. Team K&K did this with viewers and mirrors, so it'll be more convenient to just have a camera.
Advice welcome. |
7572
|
Thu Oct 18 03:45:56 2012 |
Jenne | Update | IOO | MCL, WFS triggers |
Quote: |
I've added MCL and WFS stop triggers into C1MCS/SUS model. Threshold value of MC_TRANS can be changed in the text entry located in MC2_POSITION medm screen. I tried 2 cases: trigger either blocks signal before MCL filter bank input or after output. Due to filter history in the 1 case MC2 was still slightly disturbed (C1:SUS-MC2_ULPD_VAR ~= 15) right after unlock. In the second case there was no disturbance as we zero output signal, but then I had to add "clear history" command to the mcup script.
WFS triggers block the signal before ASCPIT/YAW filter bank.
|
I've redone the WFS triggers. I left the MCL trigger alone (for now....I'll come back to it).
The trigger was setup such that (a) it was totally unclear what was going on, by looking at the WFS screen. Koji and I spent some time confused before I remembered that Den did this work recently. Also, for some reason, the triggers were just plain thresholding, not a schmidt trigger, so any time the cavity flashed, the WFS came on. Since the cavity can flash before the mcdown script has a chance to turn off the WFS servos, the outputs of the WFS filters are trying to output thousands of counts, and the signal goes through any time the cavity flashes. Not so good.
I have removed the triggering for the angular DoFs from the mcs model (leaving the MCL triggering for now). I have put new triggering into the ioo model, at the error point of the WFS loops. The idea is that if the cavity unlocks, we don't want to lose the current pointing of the mirrors. If the WFS servos were doing a lot of DC work, the bias sliders won't have the full information about where we want the mirrors to point. Since we have the integrators in FM1, removing the input signal should freeze the output signal. I need to modify the WFS on / off script so that this doesn't get turned off every lockloss.
Also, I have implemented (for the first time in a useful model, although I've done some testing in the tst model) the "wait" delay between a cavity locking and the trigger going through. The idea is that we don't necessarily want the WFS to come on simultaneously with the cavity lock. Since the wait delay resets any time it is un-triggered, this also prevents any signals from going through during cavity flashes. The wait block has 3 inputs: (1) a trigger, the output of some kind of trigger block, (2) a number of seconds to wait and (3) the model rate in Hz. The model rate should be set with a constant in the model, the trigger passed from the trigger block, and the wait time in seconds should be available as an epics input.
So far it looks like it's working as I expect, although I'm honestly too tired to do enough testing that I'm satisfied with, so I'm leaving the WFS off for the night. |
7571
|
Thu Oct 18 02:42:38 2012 |
Den | Update | SUS | PITCH damping needed |
Quote: |
I think we can put ø2mm × 10mm long magnetic material inside 4 holes with actuation magnets. Then magnetic field on the other side of the mirror will be close to one produced by actuation magnet. Magnetic cylinder center of inertia will be in the vertical plane where mirror's center of inertia is. So this should not change alignment significantly. Eddy current dumping will be applied to the end of the magnetic cylinder opposite to the magnet using aluminium disks, we have them in the clean room.
|
I've tested this approach. As we do not have required cylinders with high magnetic permittivity, I replaced them with magnets simular to actuator magnets ø2mm × 3mm long. Using them and aluminium disks from other TT I've made a "pitch dumping" construction.

Pitch Q reduced but not that much as I could expect. I did a ringdown test.
Plots:
yaw ringdown using original construction | yaw ringdown with added pitch damping
------------------------------------------------------------------------------------------------------------------------
pitch ringdown using original construction | pitch ringdown with added pitch damping


From this data I've estimated Q factor for yaw (135 vs 88) and pitch (192 vs 77) (original vs added pitch damping). Thess results diverges with the ones obtained by designes. They measured Q~40-50 for original construction. Pitch and yaw have 2 close resonances so this time domain method can not be very precise. I've measured the same with SR785.
 
In these comparison plots excitation was not the same as coils are not plugged in yet, but resonance Q factors can be compared.
|
7570
|
Wed Oct 17 19:35:58 2012 |
Koji | Update | Computers | Re: Lots of new White :( |
Solved. The power code of c1iscaux was loose.
Has anyone worked around the back side of 1Y3?
I looked into the problem. I went around the channel lists for each slow machines and found the variables are supported by c1iscaux
controls@pianosa:/cvs/cds/caltech/target/c1iscaux 0$ cd /cvs/cds/caltech/target/c1iscaux
controls@pianosa:/cvs/cds/caltech/target/c1iscaux 0$ grep C1:IF *
C1IFO_STATE.db:grecord(ai,"C1:IFO-STATE")
It seemed that the machine was not responding to ping. I went to 1Y3 and found the crate was off. Actually this is not correct.
The key was on but the power was off. I looked at the back and found the power code was loose from its inlet.
Once the code was pushed in and the crate was keyed, the white boxes got back online.
Just in case I burtrestored these slow channels by the snapshot at 6:07am on Sunday. |
7569
|
Wed Oct 17 18:41:27 2012 |
Jenne | Update | Cameras | Camera looking at ETMY baffle |
The camera titled "watec_mobile" is looking at the front of the black glass baffle (i.e. the side facing the ITM) on the ETMY table. This required (for my quick hacky solution) removing the regular ETMYF camera. Steve has a genius plan (I think) so that we can have both at the same time. Anyhow, eventually we'll move the black glass back, so we'll be back to needing just one camera.
After dinner, I'll try aligning the Yarm. |
7568
|
Wed Oct 17 11:15:05 2012 |
Den | Update | SUS | PITCH damping needed |
Quote: |
Pitch damping solution needed! It should be in the machine shop already.
|
I think we can put ø2mm × 10mm long magnetic material inside 4 holes with actuation magnets. Then magnetic field on the other side of the mirror will be close to one produced by actuation magnet. Magnetic cylinder center of inertia will be in the vertical plane where mirror's center of inertia is. So this should not change alignment significantly. Eddy current dumping will be applied to the end of the magnetic cylinder opposite to the magnet using aluminium disks, we have them in the clean room.

|
7567
|
Wed Oct 17 09:01:37 2012 |
Steve | Update | PEM | ants on the PSL table |
Quote: |
We observed one or two ants climbing over PMC optics without booties and safety glasses.
The floor was mopped with strong Bayer Home Pest Control solution in the Vertex area.
Do not work inside the 40m lab if you are sensitive to chemicals!
|
The floor is mopped again with strong PEST CONTROL SOLUTION in water in the Vertex area.
Do not plane to work in the IFO-room till noon if you are sensitive to chemicals! |
7566
|
Wed Oct 17 08:30:49 2012 |
Steve | Update | SUS | PTICH damping needed |
Quote: |
Quote: |
[Koji, Steve, Den]
TT alignment is fine, yaw damping is satisfactory, pitch damping is slow. We might want to add magnets to the mirror and attach blades to the frame for pitch edge current damping.
We are moving towards electronics testing.
|
Atm1, TT 1.5" high adaptor base will be back from the shop in 10 days.
Atm2, There is no PITCH damping, YAW edie current damping works well at 0.5 mm gap
Atm3, Adjustable Al -disc that contains a small magnet is purely designed.
We have to come up with a solution to have damping in PITCH
|
Pitch damping solution needed! It should be in the machine shop already. |
7565
|
Wed Oct 17 08:05:10 2012 |
Den | Update | General | do not leave op-table open |
Quote: |
ETMX optical table was left open. Burned toast award goes to ......?
|
me |
7564
|
Wed Oct 17 08:04:31 2012 |
Steve | Update | VAC | Roughing pumps on for oil change |
PR1, PR2 and RP3 turned on for warming up for oil change. Oil changed with 3.2L of MVT-19 fluid in each. This substitute for HE-175 will be used at the next oil change - it has 1E-6 Torr vapor pressure.
To finish this job tomorrow: 1, check oil creeping upstream 2, change air filter of air purge if pressure drops <350 mTorr 3, measure venting time of pump |
7563
|
Wed Oct 17 08:01:54 2012 |
Steve | Update | General | do not leave op-table open |
ETMX optical table was left open. Burned toast award goes to ......? |
7562
|
Tue Oct 16 21:57:47 2012 |
Den | Update | PEM | accelerometers |
All accelerometers are now at the table behind 1X4, cables are near readout box. |
7561
|
Tue Oct 16 20:40:06 2012 |
Den | Update | IOO | c1lsc DAC0 now connected to tip-tilt SOS DW boards |
Full cable path from coil driver to osem input is now ready. I've tested Ch1-4 of the left AI and left coil driver. 15 pin outputs and monitors show voltage that we expect. I've checked voltage on the other side of the cable in the clean room, it is correct. We are ready to test the coils. We need to bake osem cables asap. Hopefully, Bob will start this job tomorrow.

|
7560
|
Tue Oct 16 17:13:23 2012 |
Czarina | Summary | General | vent stuff - 4 paths |
I see 4+ possible paths for us to take, in terms of a possible vent in the next few weeks:
No Vent - Just do FPPRMI, using AS55
Mini Vent - Fix REFL path, nothing else. ~1 day at atmosphere
Medium Vent - Fix REFL path, swap G&H mirrors for LaserOptik mirrors (so also resuspend passive TTs, maybe add pitch adjustment option). ~1 week or so at atmosphere - do this rather than Mini if Jan's Finesse calc says the G&H mirrors are too rough
Mega Vent - Fix all the things, do all the things. Long time at atmosphere
The "+" is to take into account all the possible variations on "medium vent". The No, Mini and Medium options assume we'll do the Mega option later, just not immediately. |
7559
|
Tue Oct 16 17:06:47 2012 |
Steve | Update | SAFETY | safety training |
Ayaka Shoda, visiting graduate student received basic 40m specific safety training today |
Attachment 1: IMG_1735.JPG
|
|
7558
|
Tue Oct 16 16:46:20 2012 |
Vent Czar and Czarina | Summary | General | vent stuff |
We're discussing the plan for the next vent. Now that we have all the tip-tilt stuff in hand, we should get ready for the big TT installation vent ASAP. The question is what remains to be done, and when can we be ready
Stuff that needs doing:
* characterize TTs, check electrical connection of quadrupus cables, bake cables and base plates - a week or so (not including baking)
* phase map of LaserOptik mirrors (decide on needed resolution) - a week or so?
* get ready to swap G&H mirrors with LaserOptik mirrors (PR2, PR3, SR2, SR3)
* assembly of black glass beam dumps - one afternoon
* green periscope moving - day or so to make sure greens are resonant in arms, so we have something to align to
* redraw of REFL path?? (rotate 2nd refl mirror to reflect beam to the east, then add mirror to get beam out of IOO chamber viewport), cut hole in BS oplev table's box, install black beam tube
* FI camera mount - make sure it's here, baked
* active TT pitch damping plan
* passive TT weight addition and pitch alignment plan
* camera plan for taking in-chamber photos without touching the tables
* look at layout of ITMY table. POY pick-off too close to main beam. Can we move POY pick-off to BS table?
* remount black glass baffles on SOS cages.
Stuff to bake:
* Quadrupus cables
* TT base plates
* FI mirror mount for FI camera
* stuff to add to active TTs
* stuff to add to passive TTs
|
7557
|
Tue Oct 16 11:54:05 2012 |
Jenne | Update | IOO | MC alignment?? |
The MC won't survive the boosts right now. Pizza meeting is in a minute, and I won't be back to the lab before ~3:30 because of the seminar / a meeting, so someone else is welcome to try to fix it. Otherwise I'll have a look later on.
I'm leaving the autolocker disabled, so that it won't try any funny business. WFS are off, so that they don't need to be turned off by the down script. |
7556
|
Tue Oct 16 11:38:17 2012 |
Jenne | Update | LSC | More PRMI notes from last night |
Quote: |
How can you lock the PRMI without the REFL beams? c.f. this entry by Kiwamu
Which signals are you using for the locking?
I think the first priority is to find the fringes of the arms and lock them with POX/POY.
As for the POP, make sure the beam is not clipped because the in-vac steering mirrors
have been supposed to be too narrow to accommodate these two beams.
|
I was using AS55I for PRCL, and AS55Q for MICH. I snuck that into the last line of an unrelated elog, since I did both things at the same time: see elog 7551. Kiwamu's measurements (elog 6283) of the PRMI sensing matrix show that the PRCL and MICH signals are almost orthogonal in AS55 (although the optickle simulation doesn't agree with that...) He was able to lock PRMI with AS55 I&Q (elog 6293), so I thought we should be able to as well. Locking the PRMI was supposed to help tune the alignment of the PRM, not be the end goal of the night. Also, we only tried locking PRCL in the "middle right" configuration, not the "lower left" configuration, but we were seeing what looked like recycling flashes only in the "lower left" configuration.
I agree in principle that we should be working on the arms. However, since we can't use the old steer-the-beam-onto-the-cage trick to find the beam, I was hoping that we could steer the beam around and see some light leaking out of the ETM, onto the end table. However, with the 1% transmission of the ITMs and ~10ppm transmission of the ETMs, there's not a lot of light back there. I was hoping to align the PRMI so that I get flashes with a gain of 10 if I'm lucky, rather than just the 5% transmission of the PRM. With the PRMI aligned, I was expecting:
(1W through Faraday) * (10 PR gain) * (0.5 BS transmission) * (0.01 ITM transmission) * (10ppm ETM transmission) = 0.5uW on the ETM tables during PRCL flashes.
I was hoping that things would be well enough aligned that I could just go to the end table, and see the light with a viewer, although as I type this, I realize that if the beam was not on the end table (or even if it was...) any time I move the PZTs, I'd have to completely realign the PRMI in order to see the flashes. This seems untenable, unless there are no other options.
We then got sidetracked by trying to see the POP beam, and once we saw the POP beam we wanted to put something down so we could find it again. POP is also small, but not as small as expected at the end:
(1W through Faraday) * (10 PR gain) * (20ppm PR2 transmission) = 0.2mW on POP during PRCL flashes.
POP was very difficult to see, and we were only able to see it by putting the foil in the beam path, and using a viewer. I think that we once were able to see it by looking at a card with the viewer, but it's much easier with the foil. I'd like to find an iris that is shiny (the regular black iris wasn't helpful), to facilitate this alignment. Since we were just looking at the reflection off of the foil, I have no comment yet about clipping vs. not clipping. I do think however that the forward-going beam may have been easier to find....when the PRMI alignment drifted, we lost the beam, but I could still see the forward-going beam. Probably I should switch to that one, since that's the one that was lined up with the in-vac optics.
Summary:
Ideas are welcome, for how to align the beam to the Yarm (and later to the Xarm), since our old techniques won't work. Aligning the PRMI was a distraction, although in hopes of getting flashes so we could see some light at the end tables. I'm going to go see if I can look through a viewport and see the edges of the black glass aperture, which will potentially be a replacement for the steering-on-the-cage technique, but if that doesn't work, I'm running out of ideas. |
7555
|
Tue Oct 16 02:34:38 2012 |
Koji | Update | LSC | POP lens placed on POX table, 2 PRMI movies |
How can you lock the PRMI without the REFL beams? c.f. this entry by Kiwamu
Which signals are you using for the locking?
I think the first priority is to find the fringes of the arms and lock them with POX/POY.
As for the POP, make sure the beam is not clipped because the in-vac steering mirrors
have been supposed to be too narrow to accommodate these two beams. |
7554
|
Tue Oct 16 00:33:29 2012 |
Jenne | Update | LSC | POP lens placed on POX table, 2 PRMI movies |
[Evan, Jenne]
We aligned the PRMI. We definitely can lock MICH, but we're not really sure if PRCL is really being locked or not. I don't think it is.
Anyhow, we found 2 different places on the AS camera that we can align the PRMI. One (middle, right hand side of the camera), we see the same weird fringing that we've been seeing for a week or two. The other (lower left side of the camera), we see different fringing, almost reminds me more of back in the day a few months ago when the beam looked like it was expanding on each pass. As I type, Evan is uploading the movies to youtube. I *still* don't know how to embed youtube videos on the elog!
Also, we found both forward-going and backward-going POP beams coming out onto the POX table. We placed the 2" lens in the path of the backwards beam, so that we can find it again. We can't see it on an IR card, but if we put some foil where we think the beam should be, we can use a viewer to see the spot on the foil. Poking a hole in the foil made an impromptu iris.
Youtube videos:
Lower left on camera
Middle right on camera |
7553
|
Tue Oct 16 00:08:26 2012 |
Den | Update | IOO | c1lsc DAC0 now connected to tip-tilt SOS DW boards |
Quote: |
Tomorrow I'll get new SMA cables to connect the DW/AI outputs to the coil driver boards, and I'll start testing the coil driver outputs.
|
I've found a nice 16 twisted pair cable ~25m long and decided to use it as a port from 1Y3 to clean room cable instead of buying a new long one. I've added a break out board to the coil driver end to monitor outputs.

|
7552
|
Mon Oct 15 22:24:45 2012 |
Jenne | Update | Computers | Lots of new White :( |
Evan and I are starting to lock, and there is lots of new, unfortunate white stuff on several different screens.
C1:TIM-PACIFIC_STRING is gone, C1:IFO-STATE (MC state) is gone, C1:LSC-PZT..._requests are gone (all 4 of them), C1:PSL-FSS_FASTSWEEPTEST from the FSS screen is gone (although I'm not sure that that one is newly gone), lots of the WF AA lights on the LSC screen are gone.
Those are the things I find in a few minutes of not really looking around.
EDIT: IPPOS is also gone, so I can't see how my current alignment relates to old alignments. |
7551
|
Mon Oct 15 22:16:09 2012 |
Jenne | Update | SUS | All oplev gains turned to 0 |
Steve has promised to fix up all of the oplevs, but it hasn't happened yet, so I've turned all of the oplev gains to zero, so that when the optics are restored we don't have to quickly click them off.
Oplev values that were changed to zero:
PRM P=0.15, Y=-0.3
SRM P=-2.0, Y=2.0
BS P=0.2, Y=-0.2
ITMY P=2.1, Y=-2.0
ITMX P=1.0, Y=-0.5
ETMX P=-0.2, Y=-0.2
ETMY P=0.5, Y=0.6
Also, PRCL was changed in the LSC input matrix from REFL33I to AS55I, since there is no REFL beam out of the IFO :( |
7550
|
Mon Oct 15 20:45:58 2012 |
jamie | Update | IOO | c1lsc DAC0 now connected to tip-tilt SOS DW boards |
The tip-tile SOS dewhite/AI boards are now connected to the digital system.

I put together a chassis for one of our space DAC -> IDC interface boards (maybe our last?). A new SCSI cable now runs from DAC0 in the c1lsc IO chassis in 1Y3, to the DAC interface chassis in 1Y2.
Two homemade ribbon cables go directly from the IDC outputs of the interface chassis to the 66 pin connectors on the backplane of the Eurocrate. They do not go through the cross-connects, cause cross-connects are stupid. They go to directly to the lower connectors for slots 1 and 3, which are the slots for the SOS DW/AI boards. I had to custom make these cables, or course, and it was only slightly tricky to get the correct pins to line up. I should probably document the cable pin outs.
- cable 0: IDC0 on interface chassis (DAC channels 0-7) ---> Eurocrate slot 0 (TT1/TT2)
- cable 1: IDC1 on interface chassis (DAC channels 8-15)---> Eurocrate slot 2 (TT3/TT4)
As reported in a previous log in this thread, I added control logic to the c1ass front-end model for the tip-tilts. I extended it to include TT_CONTROL (model part) for TT3 and TT4 as well, so we're now using all channels of DAC0 in c1lsc for TT control.
I tested all channels by stepping through values in EPICS and reading the monitor and SMA outputs of the DW/AI boards. The channels all line up correctly. A full 32k count output of a DAC channel results in 10V output of the DW/AI boards. All channels checked out, with a full +-10V swing on their output with a full +-32k count swing of the DAC outputs.
We're using SN 1 and 2 of the SOS DW/AI boards (seriously!)
The output channels look ok, and not too noisy.
Tomorrow I'll get new SMA cables to connect the DW/AI outputs to the coil driver boards, and I'll start testing the coil driver outputs.
As a reminder: https://wiki-40m.ligo.caltech.edu/Suspensions/Tip_Tilts_IO
|
7549
|
Mon Oct 15 17:08:01 2012 |
Steve | Update | VAC | vacuum is back with some disabled valves |
Quote: |
Quote: |
Apparently all of the ION pump valves (VIPEE, VIPEV, VIPSV, VIPSE) opened, which vented the main volume up to 62 mTorr. All of the annulus valves (VAVSE, VAVSV, VAVBS, VAVEV, VAVEE) also appeared to be open. One of the roughing pumps was also turned on. Other stuff we didn't notice? Bad.
|
Several of the suspensions were kicked pretty hard (600+ mV on some sensors) as a result of this quick vent wind. All of the suspensions are damped now, so it doesn't look like we suffered any damage to suspensions.
|
CLOSE CALL on the vacuum system:
Jamie and I disabled V1, VM2 and VM3 gate valves by disconnecting their 120V solenoid actuator before the swap of the VME crate.
The vacuum controller unexpectedly lost control over the swap as Jamie described it. We were lucky not to do any damage! The ion pumps were cold and clean. We have not used them for years so their outgassing possibly accumulated to reach ~10-50 Torr
I disconnected_ immobilized and labelled the following 6 valves: the 4 large ion pump gate valves and VC1, VC2 of the cryo pump. Note: the valves on the cryo pump stayed closed. It is crucial that a warm cry pump is kept closed!
This will not allow the same thing to happen again and protect the IFO from warm cryo contamination.
The down side of this that the computer can not identify vacuum states any longer.
This vacuum system badly needs an upgrade. I will make a list. |
Attachment 1: VMEcrateout.png
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Attachment 2: IMG_1725.JPG
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Attachment 3: warning.png
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Attachment 4: shortcomings.jpg
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7548
|
Mon Oct 15 14:51:16 2012 |
Jenne | Update | SUS | SUS were kicked hard as a result |
Quote: |
Apparently all of the ION pump valves (VIPEE, VIPEV, VIPSV, VIPSE) opened, which vented the main volume up to 62 mTorr. All of the annulus valves (VAVSE, VAVSV, VAVBS, VAVEV, VAVEE) also appeared to be open. One of the roughing pumps was also turned on. Other stuff we didn't notice? Bad.
|
Several of the suspensions were kicked pretty hard (600+ mV on some sensors) as a result of this quick vent wind. All of the suspensions are damped now, so it doesn't look like we suffered any damage to suspensions. |
7547
|
Mon Oct 15 13:07:51 2012 |
jamie | Update | VAC | vacuum VME crate broken, replaced, minor vacuum mayhem ensues |
Steve and I managed to access the fuse in the vacuum VME crate, but replacing it did not bring it back up. We decided to replace the entire crate.
We manually checked that the most important valves, VC1, VM1 and V1, were all closed. We disconnected their power so that they would automatically close, and we wouldn't have to worry about them accidentally opening when we rebooted the system.
We noted where all the cables were, disconnected everything, and removed the crate. We noted that one of the values switched when we disconnected one of the IPC cables from a VME card. We'll note which one it was in a followup post. We thought that was a little strange, since the VME crate was completely unpowered.
Anyway, we removed the crate, swapped in a spare, replaced all the cards and connections, double checked everything, then powered up the crate. That's when minor chaos ensued.
When the system came back online after about 20 seconds, we heard a whole bunch of valves switching. Luckily we were able to get the medm screens back up so that we could see what was going on.
Apparently all of the ION pump valves (VIPEE, VIPEV, VIPSV, VIPSE) opened, which vented the main volume up to 62 mTorr. All of the annulus valves (VAVSE, VAVSV, VAVBS, VAVEV, VAVEE) also appeared to be open. One of the roughing pumps was also turned on. Other stuff we didn't notice? Bad.
We ran around and manually unplugged all of the ION pump valves, since I couldn't immediately pull up the vacuum control screen. Once that was done and we could see that the main volume was closed off we went back to figure out what was going on.
We got the medm vacuum control screen back (/cvs/cds/caltech/medm/c0/ve/VacControl_BAK.adl. really??) There was a lot of inconsistency between the readback states of the valves and the switch settings. Toggling the switches seemed to bring things back in line. At this point it seemed that we had control of the system again. The epics readings were consistent with what we were seeing in the vacuum rack.
We went through and closed everything that should have been closed. The line pressure between the big turbo pump TP1 and the rest of the pumps was up at atmosphere, 700 Torr. We connected the roughing pumps and pumped down the lines so that we could turn the turbos back on. Once TP2 and TP3 were up to speed, we turned on TP1 and opened V1 to start pumping the main volume back town. The main volume is at 7e-4 Torr right now.
So there are a couple of problems with the vacuum system.
- Why the hell did valves open when we rebooted the VME crate? That's very bad. That should never happen. If the system is set to come up to an unsafe state that needs to be fixed ASAP. The ION pump valves should never have opened. Nor the annulus valves.
- Why were the switches and the readbacks showing different states?
- Apparently there is no control of the turbo pumps through MEDM. This should be fixed.
I connect belledona, the laptop at the vacuum station to the wired network, so that it's connection would be less flaky.
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7546
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Mon Oct 15 10:14:22 2012 |
Den | Update | PEM | AA board |
Quote: |
I'll leave accelerometers near ETMX table. It's interesting to measure table motion in the morning when trucks drive by.
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That low frequency effect was due to AA board, now it is gone. |
7545
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Mon Oct 15 08:12:45 2012 |
Steve | Update | VAC | blank vac monitor |
VME crate blew its fuse and the fuse housing is hard to access. |
Attachment 1: blankvac.png
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7544
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Mon Oct 15 08:08:33 2012 |
steve | Update | SUS | PRM damping restored |
Quote: |
Quote: |
Quote: |
Quote: |
Yuta claims he fixed the PRM oplev by centering it the other day, but no one has left it on and watched it for a long while, to make sure it's okay. We watched it now for ~2 min, and it was good, but we're leaving the oplevs off anyway for the night. Tomorrow we should restore PRM (it's currently restored), turn on the oplevs, and let it sit to make sure it doesn't go crazy.
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PRM oplev servo was turned on with PITgain 0.5 and YAWgain -0.7
Note: gain settings were PIT 1.0 and YAW --0.5 on Jun 1, 2012 that I measured Feb 23, 2012
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It is still oscillating. Gains turned down to zero.
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Earthquake test our suspensions PRM damping restored. Oplev servo gains turned to zero.
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The PRM damping restored. Oplev PIT gain 0.15 and YAW gain -0.3 turned to zero. |
7543
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Sun Oct 14 20:51:20 2012 |
Den | Update | PEM | AA board |
Quote: |
But every ~40 min ETMX motion is much higher then ground motion at low frequencies (<5 Hz). I wonder if this a reaction of a table to outside disturbances or accelerometer issue.
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This could come from AA board, its range is +/- 2.5 V, RMS of the ETMX table motion is a few times higher then ground motion, so ETMX accelerometer signal was corrupted.

As this small AA range has already caused problems before, I decided to increase it. I've looked through the board scheme and found that all its differential line receives and output amplifiers have absolute maximum range of 40V. We used KEPKO power supply for this board with a voltage range up to 6 V. So I've replaced it with a BK PRECISION power supply and set it to +/- 15 V. Now AA board range is 7.5 V.
I'll leave accelerometers near ETMX table. It's interesting to measure table motion in the morning when trucks drive by. |
7542
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Sun Oct 14 17:26:03 2012 |
Den | Update | PEM | ETMX table |
Quote: |
I've measured ETMX table motion compared to ground motion using accelerometers. Data and settings in the xml file are at the svn directory 40m_seismic/etmx
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High frequency (>60 Hz) resonances that are present at the ETMX motion spectrum seem to be understandable. Amplification ETMX/GROUND of a factor of 2 at 1 Hz is interesting. I've monitored ACC DQ channels for a few hours and noticed that usually spectrum looks like in the previous elog. But every ~40 min ETMX motion is much higher then ground motion at low frequencies (<5 Hz). I wonder if this a reaction of a table to outside disturbances or accelerometer issue.
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Attachment 1: etmx.pdf
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7541
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Sun Oct 14 16:44:20 2012 |
Den | Update | PEM | ETMX table |
I've measured ETMX table motion compared to ground motion using accelerometers. Data and settings in the xml file are at the svn directory 40m_seismic/etmx.

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Attachment 2: 14OCT2012.pdf
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Attachment 3: 14OCT2012.xml
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<?xml version="1.0"?>
<!DOCTYPE LIGO_LW [
<!ELEMENT LIGO_LW ((LIGO_LW|Comment|Param|Time|Table|Array|Stream)*)>
<!ATTLIST LIGO_LW Name CDATA #IMPLIED Type CDATA #IMPLIED>
<!ELEMENT Comment (#PCDATA)>
<!ELEMENT Param (#PCDATA)>
<!ATTLIST Param Name CDATA #IMPLIED Type CDATA #IMPLIED Dim CDATA #IMPLIED
Unit CDATA #IMPLIED>
<!ELEMENT Table (Comment?,Column*,Stream?)>
<!ATTLIST Table Name CDATA #IMPLIED Type CDATA #IMPLIED>
... 231779 more lines ...
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7540
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Sun Oct 14 11:41:42 2012 |
Den | Update | PEM | ETMY table |
Quote: |
Accelerometers were installed on the ETMY table and nearby ground to measure amplification of the seismic noise due to the table. During this experiment ground and table motions were measured simultaneously
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I've added xml file with measurement settings and data to 40m svn at directory 40m_seismic/etmy.
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Attachment 2: 14OCT2012.pdf
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Attachment 3: 14OCT2012.xml
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<?xml version="1.0"?>
<!DOCTYPE LIGO_LW [
<!ELEMENT LIGO_LW ((LIGO_LW|Comment|Param|Time|Table|Array|Stream)*)>
<!ATTLIST LIGO_LW Name CDATA #IMPLIED Type CDATA #IMPLIED>
<!ELEMENT Comment (#PCDATA)>
<!ELEMENT Param (#PCDATA)>
<!ATTLIST Param Name CDATA #IMPLIED Type CDATA #IMPLIED Dim CDATA #IMPLIED
Unit CDATA #IMPLIED>
<!ELEMENT Table (Comment?,Column*,Stream?)>
<!ATTLIST Table Name CDATA #IMPLIED Type CDATA #IMPLIED>
... 231759 more lines ...
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7539
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Fri Oct 12 22:44:49 2012 |
Den | Update | PEM | ETMY table |
Quote: |
Seismic noise on the ETMY table measured to be a few times higher then on the floor in horizontal direction in the frequency range 50 - 200 Hz. Attached are compared spectrums of X, Y and Z motions.
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Accelerometers were installed on the ETMY table and nearby ground to measure amplification of the seismic noise due to the table. During this experiment ground and table motions were measured simultaneously.

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Attachment 1: etmy_x_psd.pdf
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Attachment 2: etmy_y_psd.pdf
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Attachment 3: etmy_z_psd.pdf
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Attachment 4: etmy_coh.pdf
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7538
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Fri Oct 12 16:59:26 2012 |
steve | Update | SUS | TT PITCH damping |
Quote: |
Quote: |
We can only decide the need of pitch damping when the coils are activated.
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Could you tell us why? Are you thinking about induced current damping?
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I was wrong The instability will be the same when the coils are actuated. |
7537
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Fri Oct 12 15:31:03 2012 |
Rijuparna | Configuration | | cavitymode scan |
Rijuparna, Manasa
Today I have checked the optical layout of the MC transmission RFPD table and measured the laser powers at different points. Manasa helped me for that. I found the power entering the RF photodiode is 0.394mW while the transmitted power of the cavity is 2.46mW. (I will give the diagram later). |
7536
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Fri Oct 12 14:01:33 2012 |
Koji | Update | SUS | TT PITCH damping |
Quote: |
We can only decide the need of pitch damping when the coils are activated.
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Could you tell us why? Are you thinking about induced current damping? |
7535
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Fri Oct 12 10:39:45 2012 |
Steve | Update | SUS | TT PITCH damping |
Quote: |
Quote: |
[Koji, Steve, Den]
TT alignment is fine, yaw damping is satisfactory, pitch damping is slow. We might want to add magnets to the mirror and attach blades to the frame for pitch edge current damping.
We are moving towards electronics testing.
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Atm1, TT 1.5" high adaptor base will be back from the shop in 10 days.
Atm2, There is no PITCH damping, YAW edie current damping works well at 0.5 mm gap
Atm3, Adjustable Al -disc that contains a small magnet is purely designed.
We have to come up with a solution to have damping in PITCH
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We can only decide the need of pitch damping when the coils are activated. |
Attachment 1: IMG_1709.JPG
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7534
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Fri Oct 12 01:56:26 2012 |
kiwamu | Update | General | Alignment situation of interferometer |
[Koji / Kiwamu]
We have realigned the interferometer except the incident beam.
The REFL beam is not coming out from the chamber and is likely hitting the holder of a mirror in the OMC chamber. 
So we need to open the chamber again before trying to lock the recycled interferometers at some point.
--- What we did
- Ran the MC decenter script to check the spot positions.
- MC3 YAW gave a - 5mm offset with an error of about the same level.
- We didn't believe in this dither measurement.
- Checked the IP-POS and IP-ANG trends.
- The trends looked stable over 10 days (with a 24 hours drift).
- So we decided not to touch the MC suspensions.
- Tried aligning PRM
- Found that the beam on the REFL path was a fake beam
- The position of this beam was not sensitive to the alignment of PRM or ITMs.
- So certainly this is not the REFL beam.
- The power of this unknown beam is about 7.8 mW
- Let the PRM reflection beam go through the Faraday
- This was done by looking at the hole of the Faraday though a view port of the IOO chamber with an IR viewer.
- Aligned the rest of the interferometer (not including ETMs)
- We used the aligned PRM as the alignment reference
- Aligned ITMY such that the ITMY reflection overlaps with the PRM beam at the AS port.
- Aligned the BS and SRM such that their associated beam overlap at the AS port
- Aligned ITMX in the same way.
- Note that the beam axis, defined by the BS, ITMX and SRM, was not determined by this process. So we need to align it using the y-arm as a reference at some point.
- After the alignment, the beam at the AS port still doesn't look clipped. Which is good.
---- things to be fixed
- Align the steering mirrors in the faraday rejected beam path (requires vent)
- SRM oplev (this is out of the QPD range)
- ITMX oplev (out of the range too) |
7533
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Thu Oct 11 21:26:40 2012 |
janosch | Update | General | PRC phase maps |
Just some plots. There is nothing new here except for the fact that I learned how to analyze phase maps myself and how to prepare them for Finesse. In other words, everything is ready for a Finesse simulation.
These phase maps show the raw measurement of ITMY, ITMX and PRC:
  
Subtracting out the tilt from all phase maps, and the curvature from the PRC (I found the fit 121m consistent with previous fits), the one obtains the following residuals that can be used in Finesse (order is again ITMY, ITMX and PRC):
  
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Attachment 3: PRC_40m.png
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7532
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Thu Oct 11 14:40:20 2012 |
Den | Update | SUS | diagonalization |
Quote: |
MC1 diagonalization is poor, better then before, but still pitch is seen in pos and yaw. Either smth is malfunctioning or flags touch sensors and do not move freely. On the plot mc1_new black lines - before, red - after rediagonalization.
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I've manually corrected MC1 input matrix by looking at UL, UR, LL, LR transfer functions between each other. This improved pos significantly and slightly yaw. |
Attachment 1: mc1.pdf
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7531
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Thu Oct 11 12:11:23 2012 |
jamie | Update | IOO | c1ass with new DAC0 output has been recompiled/install/restarted |
I rebuilt/install/restarted c1ass. It came up with no problems. It's now showing DAC0 with no errors.
After lunch I'll test the outputs. |
7530
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Thu Oct 11 12:02:15 2012 |
Den | Update | IOO | FSS |
FSS SLOW control did not drift during the lock at night with MCL path working and AC coupled.

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7529
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Thu Oct 11 11:57:40 2012 |
jamie | Update | CDS | all IOP models rebuild, install, restarted to reflect fixed ADC/DAC layouts |
Quote: |
As Rolf pointed out when he was here yesterday, all of our IOPs are filled with parts for ADCs and DACs that don't actually exist in the system. This was causing needless module error messages and IOP GDS screens that were full of red indicators. All the IOP models were identically stuffed with 9 ADC parts, 8 DAC parts, and 4 BO parts, even though none of the actual front end IO chassis had physical configurations even remotely like that. This was probably not causing any particular malfunctions, but it's not right nonetheless.
I went through each IOP, c1x0{1-5}, and changed them to reflect the actual physical hardware in those systems. I have committed these changes to the svn, but I haven't rebuilt the models yet. I'll need to be able to restart all models to test the changes, so I'm going to wait until we have a quiet time, probably next week.
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I finally got around to rebuilding, installing, and restarting all the IOP models. Everything went smoothly. I had to restart all the models on all the screens, but everything seemed to come back up fine. We now have many fewer dmesg error messages, and the GDS_TP screens are cleaner and don't have a bunch of needless red.
A frame builder restart was also required, due to name changes in unused (but unfortunately still needed) channels in the IOP. |
7528
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Thu Oct 11 11:36:52 2012 |
Steve | Update | SUS | TT pitch adjustment |
Tip Tilt pitch adjustment on existing-in vacuum suspension. This can be added by a simple installation of a 1.25" long 2-56 threaded rod with nuts. |
Attachment 1: IMG_1702.JPG
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7527
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Thu Oct 11 11:20:05 2012 |
janosch | Update | General | beam shape simulation, PRC |
I started to create a Finesse model of the PRC cavity. We have the phase maps for the PRC and the two ITMs. I could not find anything for PR2,3 and BS. All files can be found in my SVN folder /janosch/PRC40m. I used the AutoCAD model to determine angles of incidence and distances. These numbers are largely inconsistent with numbers that you can find elsewhere on the 40m wiki, but this certainly depends on what accuracy is required for interferometer alignment and I don't understand anything about alignment.
The phase maps come in a format that needs to be modified before they can be used in Finesse. I have started with this work, but maybe someone else can take over. The phase maps show tilts and the PRC also has the curvature. These have to be subtracted out before the maps can be loaded into Finesse. I asked GariLynn for the code that they use. The Finesse model (MichPRC_40m.kat) does not load the phasemaps yet, and I just wrote some random parameter values for the TEM00 input beam to the PRC. So these Gauss parameters need to be corrected.
I will only go on with this work if Rana tells me that I should do so, otherwise it is on hold until we have a volunteer. |
7526
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Thu Oct 11 01:30:11 2012 |
Den | Update | SUS | diagonalization |
Quote: |
MC1 diagonalization is poor, better then before, but still pitch is seen in pos and yaw. Either smth is malfunctioning or flags touch sensors and do not move freely. On the plot mc1_new black lines - before, red - after rediagonalization.
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I've actuated on MC1 with UL, UR, LR, LL coils in turn and measured sensor readings. All coils separately work fine from the first look.
On the plot: black - free mirror, blue - UL coil actuation, green - UR, grey - LR, red - LL. |
Attachment 1: mc1_coils.pdf
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