ID |
Date |
Author |
Type |
Category |
Subject |
13510
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Sat Jan 6 18:27:37 2018 |
gautam | Update | General | power outage - IFO recovery |
Mostly back to nominal operating conditions now.
- EX TransMon QPD is not giving any sensible output. Seems like only one quadrant is problematic, see Attachment #1. I blame team EX_Acromag for bumping some cabling somewhere. In any case, I've disabled output of the QPD, and forced the LSC servo to always use the Thorlabs "High Gain" PD for now. Dither alignment servo for X arm does not work so well with this configuration - to be investigated.
- BS Seismometer (Trillium) is still not giving any sensible output.
- I looked under the can, the little spirit level on the seismometer is well centered.
- I jiggled all the cabling to rule out any obvious loose connections - found none at the seismometer, or at the interface unit (labelled D1002694 on the front panel) in 1X5/1X6.
- All 3 axes are giving outputs with DC values of a few hundred - I guess there could've been some big earthquake in early December which screwed the internal alignment of the sensing mass in the seismometer. I don't know how to fix this.
- Attachment #2 = spectra for the 3 channels. Can't say they look very seismicy
. I've assumed the units are in um/sec.
- This is mainly bothering me in the short term because I can't use the angular feedforward on PRC alignment, which is usually quite helpful in DRMI locking.
- But I think the PRM Oplev loop is actually poorly tuned, in which case perhaps the feedforward won't really be necessary once I touch that up.
What I did today (may have missed some minor stuff but I think this is all of it):
- At EX:
- Toggled power to Thorlabs trans monitoring PD, checked that it was actually powered, squished some cables in the e- rack.
- Removed PDA55 in the green path (put there for EX laser AM/PM measurement). So green beam can now enter the X arm cavity.
- Re-connected ALS cabling.
- Turned on HV supply for EX Green PZT steering mirrors (this has to be done every time there is a power failure).
- At ITMY table:
- Removed temporary HeNe RIN/ Oplev sensing noise measurement setup. HeNe + 1" vis-coated steering mirror moved to SP table.
- Turned on ITMY/SRM Oplev HeNe.
- Undid changes on ITMY Oplev QPD and returned it to its original position.
- Centered ITMY reflected beam on this QPD.
- At vertex area
- Looked under Trillium seismometer can - I've left the clamps undone for now while we debug this problem.
- Power-cycled Trillium interface box.
- Touched up PMC alignment.
- Control room
- Recover IFO alignment using combination of IR and Green beams.
- Single arm locking recovered, dither alignment servos run to maximize arm transmission. Single arm locks holding for hours, that's good.
- The X arm dither alignment isn't working so well, the transmission never quite hits 1 and it undergoes some low frequency (T~30secs) oscillations once the transmission reaches its peak value.
- Had to do the usual ipcrm thing to get dataviewer to run on pianosa.
Next order of business:
- Recover ALS:
- aim is to replace the vertex area ALS signals derived from 532nm with their 1064nm counterparts.
- Need to touch up end PDH servos, alignment/MM into arms, and into Fibers at ends etc.
- Control the arms (with RMs misaligned) in the CARM/DARM basis using the revised ALS setup.
- Make a noise budget - specifically, we are interested in how much actuation range is required to maintain DARM control in this config.
- Recover DRMI locking
- Continue NBing.
- Do a statistical study of actuation range required for acquiring and maintaining DRMI locking.
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Attachment 1: EX_QPD_Quad1_Faulty.pdf
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Attachment 2: Trillium_faulty.pdf
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13503
|
Thu Jan 4 14:39:50 2018 |
gautam | Update | General | power outage - timing error |
As mentioned in my previous elog, the CDS overview screen "DC" indicators are all RED (everything else is green). Opening up the displays for individual CPUs, the error message shown is "0x4000", which is indicative of some sort of timing error. Indeed, it seems to me that on the FB machine, the gpstime command shows a gps time that is ~1 second ahead of the times on other FE machines.
Running gpstime on other FE machines throws up an error, saying that it cannot connect to the network to update leap second data. Not sure what this is about...
I double checked the GPS timing module, we had some issues with this in the recent past. But judging by its front panel display, everything seems to be in order...
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/bin/gpstime", line 9, in <module>
load_entry_point('gpstime==0.2', 'console_scripts', 'gpstime')()
File "/usr/lib/python3/dist-packages/pkg_resources.py", line 356, in load_entry_point
return get_distribution(dist).load_entry_point(group, name)
File "/usr/lib/python3/dist-packages/pkg_resources.py", line 2476, in load_entry_point
return ep.load()
File "/usr/lib/python3/dist-packages/pkg_resources.py", line 2190, in load
['__name__'])
File "/usr/lib/python3/dist-packages/gpstime/__init__.py", line 41, in <module>
LEAPDATA = ietf_leap_seconds.load_leapdata(notify=True)
File "/usr/lib/python3/dist-packages/ietf_leap_seconds.py", line 158, in load_leapdata
fetch_leapfile(leapfile)
File "/usr/lib/python3/dist-packages/ietf_leap_seconds.py", line 115, in fetch_leapfile
r = requests.get(LEAPFILE_IETF)
File "/usr/lib/python3/dist-packages/requests/api.py", line 60, in get
return request('get', url, **kwargs)
File "/usr/lib/python3/dist-packages/requests/api.py", line 49, in request
return session.request(method=method, url=url, **kwargs)
File "/usr/lib/python3/dist-packages/requests/sessions.py", line 457, in request
resp = self.send(prep, **send_kwargs)
File "/usr/lib/python3/dist-packages/requests/sessions.py", line 569, in send
r = adapter.send(request, **kwargs)
File "/usr/lib/python3/dist-packages/requests/adapters.py", line 407, in send
raise ConnectionError(err, request=request)
requests.exceptions.ConnectionError: ('Connection aborted.', OSError(101, 'Network is unreachable'))
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13506
|
Fri Jan 5 21:54:28 2018 |
rana | Update | General | power outage - timing error |
Rolf came here in the morning, but not sure what he did or if Jamie remotely did something. But the screen is green. |
Attachment 1: huh.png
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13507
|
Fri Jan 5 22:19:53 2018 |
gautam | Update | General | power outage - timing error |
Just putting the relevant line from email from Rolf which at least identifies the problem here:
Looks like FB time is actually off by 1 year, as your timing system does not get year info.
There still seems to be something funky with the X arm transmission PDs - I can't seem to get the triggering to switch between the QPD and the Thorlabs PD, and the QPD signal seems to be wildly fluctuating by several orders of magnitude from 0.01-100. The c1iscex FE was pulled out, and it seemed to me like someone was doing some cable re-arrangement at the X end.
I will look into this tomorrow.
Quote: |
Rolf came here in the morning, but not sure what he did or if Jamie remotely did something. But the screen is green.
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3163
|
Wed Jul 7 00:15:29 2010 |
tara,Rana | Summary | PSL | power spectral density from RefCav transmitted beam |
I measured the RC transmitted light signals here at the 40m. I made all connections through the PSL patch panel.
Other than two steering mirrors in front of the periscope, and the steering mirror for the RFPD which were used to steer
the beam into the cavity and the RFPD respectively, no optics are adjusted.
We re-aligned the beam into the cavity (the DC level increased from 2 V to 3.83V) (Fig2) (We could not recover the power back to what it was 90 days ago)
and the reflected beam to the center of the RFPD.
I measured the spectral density of the signal of the transmitted beam behind RefCav in both time and frequency domain.
This will be compared with the result from PSL lab later, so I can see how stable the signal should be.
I did not convert Vrms/rtHz to Hz/rtHz because I only look at the relative intensity of the transmitted beam which will be compared to the setup at PSL lab.
We care about this power fluctuation because we plan to measure
photo refractive noise on the cavity's mirros
(this is the noise caused by dn/dT in the coatings and the substrate,
the absorption from fluctuating power on the coating/mirror changes
the temperature which eventually changes the effective length of the cavity as seen by the laser.)
The plan is to modulate the power of the beam going into the cavity,
the absorption from ac part will induce frequency noise which we want to see.
Since the transmitted power of the cavity is proportional to the power inside the cavity.
Fluctuations from other factors, for example, gain setting, will limit our measurement.
That's why we are concerned about the stability of the transmitted beam and made this measurement.
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Attachment 1: RIN_rftrans.png
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Attachment 2: tara.png
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3164
|
Wed Jul 7 10:42:29 2010 |
Koji | Summary | PSL | power spectral density from RefCav transmitted beam |
How do you calibrate this to Hz/rtHz?
Quote: |
I measured the RC transmitted light signals here at the 40m. I made all connections through the PSL patch panel. No optics/PD were touched.
I measured the spectral density of the signal of the transmitted beam behind RefCav in both time and frequency domain.
This will be compared with the result from PSL lab later, so I can see how stable the signal should be.
We re-aligned the beam into the cavity (the DC level increased from 2 V to 3.83V)
and the reflected beam to the center of the RFPD.
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9506
|
Fri Dec 20 20:04:01 2013 |
Steve | Update | VAC | power supply replaced with a short vent |
Quote: |
Quote: |
Instrument rack power supplies checked and labeled at present loads.
The vacuum rack Sorensen is running HOT! Their is only 0.3A load at 24V There is plenty of space around it.
It is alarming to me because all vacuum valve positions are controlled by this 24V
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The temperature went down to room temp with temporary fan in the back. Voltage and current are stable.
Regardless, it will be replaced early next week.
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Koji, Steve
It was a bad experience again with our vacuum system. The valves went crazy as we rebooted the computer. This was required for the swap in of a good 24V power supply.
The IFO was vented to 27 Torr through the annuloses, VA6, V7, Maglev,VM2 and VM1 (VC2 was open too)
I just opened the PSL shutter after a 4 hours pumpdown.
Condition: annuloses are not pumped, the IFO and the RGA are pumped as Atm2 shows
I will be here tomorrow morning to switch over to vacuum normal.
More details later
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Attachment 1: 4hrPumpdown.png
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Attachment 2: pumpdownAfterHickup.png
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Attachment 3: PSpumpdown.png
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9508
|
Fri Dec 20 23:00:41 2013 |
Koji | Update | VAC | power supply replaced with a short vent |
I'm leaving the 40m now. IFO is aligned. Everything look good.
- The main volume P1=5e-4, CC1=1.4e-5 is still pumped by TP1 and TP2
- RGA P4<0e-4, CC4 2.1e-7, is pumped by TP3
- The annuluses are isolated.
- RP1/2/3 are off. |
9516
|
Fri Jan 3 11:18:41 2014 |
Steve | Summary | VAC | power supply replaced with a short vent |
Quote: |
Quote: |
The temperature went down to room temp with temporary fan in the back. Voltage and current are stable.
Regardless, it will be replaced early next week.
|
Koji, Steve
It was a bad experience again with our vacuum system. The valves went crazy as we rebooted the computer. This was required for the swap in of a good 24V power supply.
The IFO was vented to 27 Torr through the annuloses, VA6, V7, Maglev,VM2 and VM1 (VC2 was open too)
I just opened the PSL shutter after a 4 hours pumpdown.
Condition: annuloses are not pumped, the IFO and the RGA are pumped as Atm2 shows
I will be here tomorrow morning to switch over to vacuum normal.
More details later
|
Events of the power supply swap:
1, Tested 24V DC ps from Todd
2, Closed V1, VM1 and all annulos valves to create safety net for the reboot. Turbo pumps left on running.
3, Turned computer off
4, Swap power supplies and turned it on
5, Turning the power on of c1vac2 created caos switching of valves. This resulted in a air vent as shown below.
6, VM1 was jammed and it was unable to close. The IOO beam shutter closed and the IFO was venting with air for a few minutes. Maglev did an emergency shut down. TP2's V4 and TP3' V5 closed. RP1 and RP3 roughing pumps turned on, their hose was not connected as usual. The RGA shut down to protect itself.
7, Closed annulos valves, stoped the vent at P1 27 torr as the vacuum control was manually recovered
8, The Maglev and the annuloses were roughed out 500 mtorr . The Maglev was restarted.
9, The IFO pump down followed std procedure from 27 torr. VM1 was moving again as the pressure differential was removed from it.
Remember: next time at atm .....rough down the cryo volume from 27 torr ! |
Attachment 1: rebootVENT.png
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9510
|
Sat Dec 21 10:53:35 2013 |
Steve | Update | VAC | power supply replaced with a short vent-pumpdown completed |
The recovery- pumpdown reached valve configuration vacuum normal at 20 hours, cc1 7.7e-6 Torr
Lesson learned: turn all pumps off, close all valves before you reboot ! like you would prepare for AC power shut down.
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Attachment 1: 20hrsVacNormal.png
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6860
|
Sat Jun 23 18:44:15 2012 |
steve | Update | General | power surge has no effect on the lab |
I was notified by CIT Utilities that there was a power surge or short power outage this after noon.
Lab conditions are normal: c1ioo is down. The south arm AC was off......I turned it back on. |
7088
|
Mon Aug 6 09:46:31 2012 |
steve | Update | IOO | poweroutage turns laser off |
. Power outage turned off the PSL Innolight laser on Sunday afternoon. It was turned back on and locked happily right on. The green lasers were not effected.
CALIFORNIA INSTITUTE OF TECHNOLOGY
FACILITIES MANAGEMENT
UTILITY & SERVICE INTERRUPTION
**PLEASE POST**
Building: CAMPUS WIDE
Date: SUNDAY, AUGUST 6, 2012
Time: 3:41 PM
Interruption: ELECTRICAL POWER DISTRIBUTION
Contact: MIKE ANCHONDO, X-4999, OR TOM BRENNAN, X-4984
* THIS PAST SUNDAY AFTERNOON ABOUT 3:40 PM, PASADENA WATER AND POWER
EXPERIENCED A FAULT ON THEIR POWER DISTRIBUTION SYSTEM. THIS CAUSED
A SEVERE VOLTAGE SAG WHICH AFFECTED THE CALTECH CAMPUS. THE FAULT WAS
NOT ON A CALTECH CIRCUIT.
(If there is a problem with this Interruption, please notify
the Service Center X-4717 or the above Contact as soon as possible.
If no response is received we will proceed with the interruption.)
Jerry Thompson,
Interim Director of Campus Operations & Maintenance
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7800
|
Sat Dec 8 04:12:38 2012 |
Den | Update | LSC | prcl |
Today I wanted to check that AS and REFL beams are real and contain proper information about interferometer. For this I locked YARM using AS55_I and REFL11_I. Then I compared spectrum with POY11_I locking. Everything is the same. I've also adjusted phase rotations of AS55 (0.2 ->24) and REFL11 (-34.150 -> -43).
Then I've locked MICH and aligned EMTs such that ASDC was close to zero. Then I locked PRCL and aligned PRM. Power buildup was 50.

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8446
|
Fri Apr 12 02:56:34 2013 |
Den | Update | Locking | prcl angular motion |
I compared PCRL and XARM angular motions by misaligning the cavities and measuring power RIN. Divergence angles for both cavities I calculated to be 100 urad.
XARM pointing noise sums from input steering TTs, PR2 and PR3 TTs, BS, ITMX, ETMY.
PRCL noise - from input TT, PRM, PR2 and PR3 TT, BS, ITMX, ITMY.
I would expect these noises to be the same as angular motion of different optics measured by oplves is simular. We do not have oplves on TT but they are present in both passes.
I measured RIN and converted to angle. Sharp 1 Hz resonance at XARM pointing spectrum is due to EMTX, it is not seen by PRCL. Other then that XARM is much quiter, especially at 3 - 30 Hz.
As PRM is the main difference in two passes, I checked its spectrum. When PRCL was locked I excited PRM in pitch and yaw. I could see this excitation at RIN only when the peak was 100 times higher then background seismic noise measured by oplev.

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Attachment 2: oplev_exc.pdf
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8447
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Fri Apr 12 09:20:32 2013 |
rana | Update | Locking | prcl angular motion |
How is the cavity g-factor accounted for in this calculation? |
8449
|
Fri Apr 12 13:21:34 2013 |
Den | Update | Locking | prcl angular motion |
Quote: |
How is the cavity g-factor accounted for in this calculation?
|
I assume that pointing noise and dc misalignment couples 00 to 01 by a factor theta / theta_cavity
Inside the cavity 01 is suppressed by 2/pi*F*sin(arccos(sqrt(g_cav))).
For the XARM this number is 116 taking g-factor to be 0.32. So all pointing noise couples to power RIN.
Suppression factor inside PRC is 6.5 for g-factor 0.97. This means that 85% of jitter couples to RIN, I accounted for this factor while converting RIN to angle.
I did not consider translational motion of the beam. But still PRC RIN can not be explained by oples readings as we can see exciting optics in pitch and yaw. I suspect this RIN is due to PR3, as it can create stronger motion in yaw than in pitch due to incident angle and translational motion of the mirror. I do not have a number yet. |
8450
|
Sat Apr 13 03:45:51 2013 |
rana | Update | Locking | prcl angular motion |
Maybe its equivalent, but I would have assumed that the input beam is fixed and then calculate the cavity axis rotation and translation. If its small, then the modal expansion is OK. Otherwise, the overlap integral can be used.
For the ETM motion, its a purely translation effect, whereas its tilt for the ITM. For the PRM, it is also a mostly translation effect as calculated at the PRC waist position (ITM face). |
8451
|
Sat Apr 13 23:11:04 2013 |
Den | Update | Locking | prcl angular motion |
Quote: |
For the PRM, it is also a mostly translation effect as calculated at the PRC waist position (ITM face).
|
I made another estimation assuming that PRCL RIN is caused by translation of the cavity axis:
- calibrated RIN to translation, beam waist = 4mm
- measured PRM yaw motion using oplev
- estimated PR3 TT yaw motion: measured BS yaw spectrum with oplev OFF, divided it by pendulum TF with f0=0.9 Hz, Q=100 (BS TF), multiplied it by pendulum TF with f0 = 1.5 Hz, Q = 2 (TT TF with eddy current damping), accounted for BS local damping that reduces Q down to 10.
PRM and TT angular motion to cavity axis translation I estimated as 0.11 mm/urad and 0.22 mm/urad assuming that TTs are flat. We can make a more detailed analysis to account for curvature.
I think beam motion is caused by PR3 and PR2 TT angular motion. I guess yaw motion is larger because horizontal g-factor is closer to unity then vertical. |
Attachment 1: pointing.pdf
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8454
|
Sun Apr 14 17:56:03 2013 |
rana | Update | Locking | prcl angular motion |
Quote: |
Quote: |
For the PRM, it is also a mostly translation effect as calculated at the PRC waist position (ITM face).
|
I made another estimation assuming that PRCL RIN is caused by translation of the cavity axis:
- calibrated RIN to translation, beam waist = 4mm
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In order to get translation to RIN, we need to know the offset of the input beam from the cavity axis...
This should be possible to calibrate by putting a pitch and yaw excitation lines into the PRM and measuring the RIN.
See secret document from Koji. |
8564
|
Mon May 13 18:44:04 2013 |
Jenne | Update | Locking | prcl angular motion |
I want to redo this estimate of where RIN comes from, since Den did this measurement before I put the lens in front of the POP PD.
While thinking about his method of estimating the PR3 effect, I realized that we have measured numbers for the pendulum frequencies of the recycling cavity tip tilt suspensions.
I have been secreting this data away for years. My bad. The relevant numbers for Tip Tilts #2 and #3 were posted in elog 3425, and for #4 in elog 3303. However, the data for #s 1 and 5 were apparently never posted. In elog 3447, I didn't put in numbers, but rather said that the data was taken.
Anyhow, attached is the data that was taken back in 2010. Look to elog 7601 for which TT is installed where.
Conclusion for the estimate of TT motion to RIN - the POS pendulum frequency is ~1.75Hz for the tip tilts, with a Q of ~2. |
Attachment 1: TT_Q_measurements.pdf
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14437
|
Wed Feb 6 10:07:23 2019 |
Chub | Update | | pre-construction inspection |
The Central Plant building will be undergoing seismic upgrades in the near future. The adjoining north wall along the Y arm will be the first to have this work done, from inside the Central Plant. Project manager Eugene Kim has explained the work to me and also noted our concerns. He assured me that the seismic noise from the construction will be minimized and we will always be contacted when the heaviest construction is to be done.
Tomorrow at 11am, I will bring Mr. Kim and a few others from the construction team to look at the wall from inside the lab. If you have any questions or concerns that you want to have addressed, please email them to me or contact Mr. Kim directly at x4860 or through email at eugene.kim@caltech.edu . |
5591
|
Fri Sep 30 19:12:56 2011 |
Koji | Update | General | prep for poweroutage |
[Koji Jenne]
The lasers were shutdown
The racks were turned off
We could not figure out how to turn off JETSTOR
The control room machines were turned off
FInally we will turn off nodus and linux1 (with this order).
Hope everything comes back with no trouble
(Finger crossing) |
13383
|
Tue Oct 17 17:53:25 2017 |
jamie | Summary | LSC | prep for tests of Gabriele's neural network cavity length reconstruction |
I've been preparing for testing Gabriele's deep neural network MICH/PRCL reconstruction. No changes to the front end have been made yet, this is all just prep/testing work.
Background:
We have been unable to get Gabriele's nn.c code running in kernel space for reasons unknown (see tests described in previous post). However, Rolf recently added functionality to the RCG that allows front end models to be run in user space, without needing to be loaded into the kernel. Surprisingly, this seems to work very well, and is much more stable for the overall system (starting/stopping the user space models will not ever crash the front end machine). The nn.c code has been running fine on a test machine in this configuration. The RCG version that supports user space models is not that much newer than what the 40m is running now, so we should be able to run user space models on the existing system without upgrading anything at the 40m. Again, I've tested this on a test machine and it seems to work fine.
The new RCG with user space support compiles and installs both kernel and user-space versions of the model.
Work done:
- Create 'c1dnn' model for the nn.c code. This will run on the c1lsc front end machine (on core 6 which is currently empty), and will communicate with the c1lsc model via SHMEM IPC. It lives at:
- /opt/rtcds/userapps/release/isc/c1/models/c1dnn.mdl
- Got latest copy of nn.c code from Gabriele's git, and put it at:
- /opt/rtcds/userapps/release/isc/c1/src/nn/
- Checked out the latest version of the RCG (currently SVN trunk r4532):
- /opt/rtcds/rtscore/test/nn-test
- Set up the appropriate build area:
- /opt/rtcds/caltech/c1/rtbuild/test/nn-test
- Built the model in the new nn-test build directory ("make c1dnn")
- Installed the model from the nn-test build dir ("make install-c1dnn")
Test:
I tried a manual test of the new user space model. Since this is a user space process running it should have no affect on the rest of the front end system (which it didn't):
- Manually started the c1dnn EPICS IOC:
- Tried running the model user-space process directly:
Unfortunately, the process died with an "ADC TIMEOUT" error. I'm investigating why.
Once we confirm the model runs, we'll add the appropriate SHMEM IPC connections to connect it to the c1lsc model. |
Attachment 1: c1dnn.png
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13390
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Wed Oct 18 12:14:08 2017 |
jamie | Summary | LSC | prep for tests of Gabriele's neural network cavity length reconstruction |
Quote: |
I tried a manual test of the new user space model. Since this is a user space process running it should have no affect on the rest of the front end system (which it didn't):
- Manually started the c1dnn EPICS IOC:
- Tried running the model user-space process directly:
Unfortunately, the process died with an "ADC TIMEOUT" error. I'm investigating why.
Once we confirm the model runs, we'll add the appropriate SHMEM IPC connections to connect it to the c1lsc model.
|
I tried moving the model to c1ioo, where there are plenty of free cores sitting idle, and the model seems runs fine. I think the problem was just CPU contention on the c1lsc machine, where there were only two free cores and the kernel was using both for all the rest of the normal user space processes.
So there are two options:
- Use cpuset on c1lsc to tell the kernel to remove all other processes from CPU6 and save it just for the c1dnn model. This should not have any impact on the running of c1lsc, since that's exactly what would be happening if we were running the model in kernel space (e.g. isolating the core for the front end model). The auxilliary support user space processes (epics seq/ioc, awgtpman) should all run fine on CPU0, since that's what usually happens. Linux is only using the additional core since it's there. We don't have much experience with cpuset yet, though, so more offline testing will be required first.
- Run the model on c1ioo and ship the needed signals to/from c1lsc via PCIe dolphin. This is potentially slightly more invasive of a change, and would put more work on the dolphin network, but it should be able to handle it.
I'm going to start testing cpuset offline to figure out exactly what would need to be done. |
6892
|
Fri Jun 29 02:17:40 2012 |
yuta | Update | IOO | prep for the vent - beam attenuating |
[Koji, Jamie, Yuta]
We attenuated the incident beam (1.2 W -> 11 mW) to the vacuum chamber to be ready for the vent.
The beam spot on the MC mirrors didn't changed significantly, which means the incident beam was not shifted so much.
What we did:
1. Installed HWP, PBS(*) and another HWP between the steering mirrors on PSL table for attenuating the beam. We didn't touched steering mirrors(**), so the incident beam to the IFO should be recovered easily, by just taking HWPs and PBS away. The power to the MC was reduced from 1.2 W to 11 mW.
(*) We stole PBSO from the AS AUX laser setup.
(**) Actually, we accidentally touched one of the steering mirrors, but we recovered them. We did the recovery tweaking the touched nob and minimizing the MC reflection. We confirmed the incident beam was recovered by measuring MC beamspot positions(below).
2. Aligned PBS by minimizing MC reflection, adjusted first HWP so that the incident beam will be ~10 mW, and adjusted last HWP to minimize MC reflection (make the incident beam to the MC be p-polarization).
3. To do the alignment and adjusting, we put 100% reflection mirror (instead of 10% BS) for the MC reflection PD to increase the power to the PD. That means, we don't have MC WFS right now.
4. Tweaked MC servo gains to that we can lock MC in low power mode. It is quite stable right now. We didn't lose lock during beam spot measurement.
5. Measured beam spot positions on the MC mirrors and convinced that the incident beam was not shifted so much (below). They look like they moved ~0.2 mm, but it is with in the error of the MC beam spot measurement.
# filename MC1pit MC2pit MC3pit MC1yaw MC2yaw MC3yaw (spot positions in mm)
./dataMCdecenter/MCdecenter201206281154.dat 3.193965 4.247243 2.386126 -6.639432 -0.574460 4.815078 this noon
./dataMCdecenter/MCdecenter201206282245.dat 3.090762 4.140716 2.459465 -6.792872 -0.651146 4.868740 after recovered steering mirrors
./dataMCdecenter/MCdecenter201206290135.dat 2.914584 4.240889 2.149244 -7.117336 -1.494540 4.955329 after beam attenuation
6. Rewrote matlab code sensemcass.m to python script sensemcass.py. This script is to calculate beam spot positions from the measurement data(see elog #6727). I think we should make senseMCdecenter script better, too, since it takes so much time and can't stop and resume the measurement if MC is unlocked. |
6893
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Fri Jun 29 03:21:32 2012 |
yuta | Update | General | prep for the vent - others |
1. Turned off high voltage power supplies for PZT1/2 (input PZTs) and OMC stage 1/2. They live in 1Y3 rack and AUX_OMC_NORTH rack.
2. Restored all IFO optics alignment to the position where I aligned this afternoon (for SRM, I didn't aligned it; it restored at the saved value on May 26).
3. Centered all the oplevs. They can be used for a reference for alignment change before and after the vent.
I will leave PSL mechanical shutter and green shutters closed just in case.
Some MEDM screenshots below.
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14022
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Tue Jun 26 20:59:36 2018 |
aaron | Update | OMC | prep for vent in a couple weeks |
I checked out the elog from the vent in October 2016 when the OMC was removed from the path. In the vent in a couple weeks, we'd like to get the beam going through the OMC again. I wasn't really there for this last vent and don't have a great sense for how things go at the 40m, but this is how I think the procedure for this work should approximately go. The main points are that we'll need to slightly translate and rotate OM5, rotate OM6, replace one mirror that was removed last time, and add some beam dumps. Please let me know what I've got wrong or am missing.
[side note, I want to make some markup on the optics layouts that I see as pdfs elsewhere in the log and wiki, but haven't done it and didn't much want to dig around random drawing software, if there's a canonical way this is done please let me know.]
Steps to return the OMC to the IFO output:
Complete non-Steve portions of the pre-vent checklist (https://wiki-40m.ligo.caltech.edu/vent/checklist)
Steve needs to complete his portions of the checklist (as in https://nodus.ligo.caltech.edu:8081/40m/12557)
Need to lock some things before making changes I think—but I’m not really sure about these, just going from what I can glean from the elogs around the last vent
-
Lock the IMC at low power
Align the arms to green
Lock the arms
Center op lev spots on QPDs
- Is there a separate checklist for these things? Seems this locking process happens every time there is a realignment or we start any work, which makes sense, so I expect it is standardized.
Turn/add optics in the reverse order that Gautam did
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Check table leveling first?
Rotate OM5 to send the beam to the partially transmissive mirror that goes to the OMC; currently OM5 is sent directly to OM6. OM5 also likely needs to be translated forward slightly; Gautam tried to maintain 45 deg AOI on OM5/6.
A razor beam dump was also removed, which should be replaced (see attachment 1 on https://nodus.ligo.caltech.edu:8081/40m/12568)
May need to rotate OM6 to extract AS beam again, since it was rotated last time
Replace the mirror just prior to the window on the AP table, mentioned here in attachment 3: https://nodus.ligo.caltech.edu:8081/40m/12566
-
There is currently a rectangular weight on the table where the mirror was, for leveling
Since Gautam had initially made this change to avoid some backscattered beams and get a little extra power, we may need to add some beam dumps to kill ghosts
- This is also mentioned in 12566 linked above, the dumps are for back-reflection off the windows of the OMC
Center beam in new path
Check OMC table leveling
AS beam should be round on the camera, with no evidence of clipping on any optics in the path (especially check downstream of any changes)
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Wed Apr 27 18:14:48 2011 |
kiwamu | Update | LSC | preparation for DRMI locking : RF status |

POX11 (see this entry) is now listed as REFL11 (on the very top row).
We will rename POY11 to POP11 for DRMI locking.
The files are on https://nodus.ligo.caltech.edu:30889/svn/trunk/suresh/40m_RF_upgrade/. |
2644
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Fri Feb 26 15:32:13 2010 |
steve | Configuration | VAC | preparation for power outage: vacuum all off |
There is a planned power outage tomorrow, Saturday from 7am till midnight.
I vented all annulies and switched to ALL OFF configuration. The small region of the RGA is still under vacuum.
The vac-rack: gauges, c1vac1 and UPS turned off. |
Attachment 1: ventd3.jpg
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13806
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Wed May 2 10:03:58 2018 |
Steve | HowTo | SEI | preparation of load cell measurement at ETMX |
Gautam and Steve,
We have calibrated the load cells. The support beams height monitoring is almost ready.
The danger of this measurment that the beams height changes can put shear and torsional forces on this formed (thin walled) bellow
They are designed for mainly axial motion.
The plan is to limit height change to 0.020" max
0, center oplev at X arm locked
1, check that jack screws are carrying full loads and set height indicator dials to zero ( meaning: Stacis is bypassed )
2, raise beam height with aux leveling wedge by 0.010" on all 3 support point and than raise it an other 0.005"
3, replace levelling wedge with load cell that is centered and shimmed. Dennis Coyne pointed out that the Stacis foot has to be loaded at the center of the foot and formed bellow can shear at their limits.
4, lower the support beam by 0.005" ......now full load on the cells
Note: jack screw heights will not be adjusted or touched.......so the present condition will be recovered
Quote: |
We could use similar load cells to make the actual weight measurement on the Stacis legs. This seems practical in our case.
I have had bad experience with pneumatic Barry isolators.
Our approximate max compression loads are 1500 lbs on 2 feet and 2500 lbs on the 3rd one.
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Attachment 1: loadcellCAL500.pdf
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Attachment 2: 3loadcellwcontr.jpg
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Attachment 3: loadcellLocation.pdf
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Attachment 4: DSC01009.JPG
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Attachment 5: jack_screw.jpg
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Attachment 6: ETMX_NW_foot_STACIS.pdf
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Thu May 3 09:56:42 2018 |
Steve | HowTo | SEI | preparation of load cell measurement at ETMX |
[ Dennis Coyne' precision answer ]
Differential Height between Isolators
According to a note on the bellows drawing (D990577-x0/A), the design life of the bellows at ± 20 minutes rotational stroke is 10,000 cycles. A 20 minute angular (torsional) rotation of the bellows corresponds to 0.186" differential height change across the 32" span between the chamber support beams (see isolator bracket, D000187-x0/B).
Another consideration regarding the bellows is the lateral shear stress introduced by the vertical translation. The notes on the bellows drawing do not give lateral shear limits. According to MDC's web page for formed bellows in this size range the lateral deflection limit is approximately 10% of the "live length" (aka "active length", or length of the convoluted section). According to the bellows drawing the active length is 3.5", so the maximum allowable lateral deflection should be ~0.35".
Of course when imposing a differential height change both torsional and lateral shear is introduced at the same time. Considering both limits together, the maximum differential height change should be < 0.12".
One final consideration is the initial stress to which the bellows are currently subjected due to a non-centered support beam from tolerances in the assembly and initial installation. Although we do not know this de-centering, we can guess that it may be of the order of ~ 0.04". So the final allowable differential height adjustment from the perspective of bellows stress is < 0.08". Steve: accumulated initial stress is unknown. We used to adjust the original jack screws for IFO aligment in the early days of ~1999. This kind of adjustment was stopped when we realized how dangereous it can be. The fact is that there must be unknown amount of accumulated initial stress. This is my main worry but I'm confident that 0.020" change is safe.
So, with regard to bellows stress alone, your procedure to limit the differential height change to <0.020" is safe and prudent.
However, a more stringent consideration is the coplanarity requirement (TMC Stacis 2000 User's Manual, Doc. No. SERV 04-98-1, May 6, 1991, Rev. 1), section 2, "Installation",which stipulates < 0.010"/ft, or < 0.027" differential height across the 32" span between the chamber support beams. Again, your procedure to limit the differential height change to < 0.02" is safe.
Centered Load on the STACIS Isolators
According to the TMC Stacis 2000 User's Manual (Document No. SERV 04-98-1, May 6, 1991, Rev. 1), section 2, "Installation", typical installations (Figure 2-3) are with one payload interface plate which spans the entire set of 3 or 4 STACIS actuators. Our payload interface is unique.
Section 2.3.1, "Installation Steps": "5. Verify that the top of each isolator is fully under the payload/interface plate; this is essential to ensure proper support and leveling. The payload or interface plate should cover the entire top surface of the Isolator or the entire contact area of the optional jack."
section 2.3.2, "Payload/STACIS Interface": "... or if the supporting points do not completely cover the top surface of each Isolator, an interface plate will be needed."
The sketch in Figure 2-2 indicates an optional leveling jack which appears to have a larger contact surface area than the jacks currently installed in the 40m Lab. Of course this is just a non-dimensioned sketch. Are the jacks used by the 40m Lab provided by TMC, or did we (LIGO) choose them? I beleive Larry Jones purchased them.
A load centering requirement is not explicitly stated, but I think the stipulation to cover the entire top surface of each actuator is not so much to reduce the contact stress but to entire a centered load so that the PZT stack does not have a reaction moment.
From one of the photos in the 40m elog entry (specifically jack_screw.jpg), it appears that at least some isolators have the load off center. You should use this measurement of the load as an opportunity to re-center the loads on the Isolators.
In section 2.3.3, "Earthquake Restraints" restraints are suggested to prevent damage from earth tremors. Does the 40m Lab have EQ restraints? Yes, it has
Screw Jack Location
I could not tell where all of the screw jacks will be placed from the sketch included in the 40m elog entry which outlines the proposed procedure.
Load Cell Locations
The sketch indicates that the load cells will be placed on the center of the tops of the Isolators. This is good. However while discussing the procedure with Gautam he said that he was under the impression that the load cell woudl be placed next to the leveling jack, off-center. This condition may damage the PZT stack. I suggest that the leveling jack be removed and replaced (temporarily) with the load cell, plus any spacer required to make up the height difference. Yes
If you have any further question, just let me know.
Dennis
Dennis Coyne
Chief Engineer, LIGO Laboratory
California Institute of Technology
MC 100-36, 1200 E. California Blvd.
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13840
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Mon May 14 08:55:40 2018 |
Dennis Coyne | HowTo | SEI | preparation of load cell measurement at ETMX |
follow up email from Dennis 5-13-2018. The last line agrees with the numbers in elog13821.
Hi Steve & Gautam,
I've made some measurements of the spare (damaged) 40m bellows. Unfortunately neither of our coordinate measurement arms are currently set up (and I couldn't find an appropriate micrometer or caliper), so I could not (yet) directly measure the thickness. However from the other dimensional measurements, and a measurement of the axial stiffness (100 lb/in), and calculations (from the Standards of the Expansion Joint Manufacturers Association (EJMA), 6th ed., 1993) I infer a thickness of 0.010 inch in . This is close to a value of 0.012 in used by MDC Vacuum for bellows of about this size.
I calculate that the maximum allowable torsional rotation is 1.3 mrad. This corresponds to a differential height, across the 32 in span between support points, of 0.041 in.
In addition using the EJMA formulas I find that one can laterally displace the bellows by 0.50 inch (assuming a simultaneous axial displacement of 0.25 inch, but no torsion), but no more than ~200 times. I might be good to stay well below this limit, say no more than ~0.25 inch (6 mm).
If interested I've uploaded my calculations as a file associated with the bellows drawing at D990577-A/v1.
BTW in some notes that I was given (by either Larry Jones or Alan Weinstein) related to the 40m Stacis units, I see a sketch from Steve dated 3/2000 faxed to TMC which indicates 1200 lbs on each of two Stacis units and 2400 on the third Stacis.
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5089
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Tue Aug 2 02:35:23 2011 |
kiwamu | Update | General | preparation of the vent : status and plan |
The vent will take place on Wednesday.
Plan for Tuesday :
(Morning) Preparation of necessary items for the low power MC (Steve / Jamie)
(Daytime) Measurement of the MC spot positions (Suresh)
(Daytime) Arm length measurement (Jenne)
(Nighttime) Locking of the low power MC (Kiwamu / Volunteers)
Plan for Wednesday :
(Early morning) Final checks on the beam axis, all alignments and green light (Steve / Kiwamu / Volunteers )
(Morning) Start the vent (Steve)
(daytime-nighttime) Taking care of the Air/Nitrogen cylinders (Everybody !!)
Status of the vent preparation :
(not yet) Low power MC
(ongoing) Measurement of the arm lengths
(ongoing) Measurement of the MC spot positions
(80% done) Estimation of the tolerance of the arm length (#5076)
(done) Alignment of the Y green beam (#5084)
(done) Preparation of beam dumps (#5047)
(done) Health check of shadow sensors and the OSEM damping gain adjustment (#5061)
(done) Alignment of the incident beam axis (#5073)
(done) Loss measurement of the arm cavities (#5077) |
5078
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Sun Jul 31 22:48:35 2011 |
kiwamu | Summary | General | preparation of the vent : status update |
Status update for the vent preparation:
The punchline is : We can not open the chamber on Monday !
##### Task List for the vent preparation #####
(not yet) Low power MC
(not yet) Measurement of the arm lengths
(not yet) Alignment of the Y green beam (#5066)
(not yet) Measurement of the MC spot positions
(80% done) Estimation of the tolerance of the arm length (#5076)
(done) Preparation of beam dumps (#5047)
(done) Health check of shadow sensors and the OSEM damping gain adjustment (#5061)
(done) Alignment of the incident beam axis (#5073)
(done) Loss measurement of the arm cavities (#5077)
Quote from #5048 |
Quote: |
The vent will start from 1 st of August !
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5080
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Mon Aug 1 08:52:37 2011 |
steve | Update | VAC | preparation to vent |
Both arms locked easely around 1V transmited. We should recenter oplevs. |
Attachment 1: pztsteering.png
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Attachment 2: vac1Aug2011.png
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Attachment 3: PEM200d.jpg
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2778
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Wed Apr 7 09:00:01 2010 |
steve | HowTo | PEM | prepare to open chamber |
In order to minimize the diffusion of more dust particles into the vented IFO vacuum envelope
BEFORE opening chamber:
-Have a known plan,
-Heavy 1" thick door requires 3 persons- of one experienced and one certified crane operator and steel tow safety shoes
-Block IFO beams, be ware of experimental set up of other hazards: 1064, visible or new-special installation
- Look at the particle counter, do not open above 6,000 particles of 0.5 micron. Construction activities are winding down. See plot of 35 days since we vented.
-Have clean door stand for heavy door, covered with merostate at the right location and dry-clean screws for light covers,
-Prepare lint free wipers for o-rings,(no solvent on o-ring!) Kimwipes for outside of chamber and metal covers, methanol and powder free gloves
-Wipe with wet Kimwipe-tissue of methanol around the door, chamber of interest and o-ring cover ring
-Cut door covering merostate and tape it into position,..if in place...check folded-merostate position, if dusty... replace it
-Is your cleanroom garment clean?.......if in doubt ....replace it
-Keep surrounding area free and clean
-Make sure that HEPAs are running: PSL-enclosure, two mobile units and south end flow banch
-Check the tools: are they really clean? wipe it with wet Kimwipe, do you see anything on the Kimwipe?
-You are responsible to close chamber ASAP with light door or doors as you finished for the day.
Merostate cover down is appropriate during daily brakes. |
Attachment 1: 0.5micron.jpg
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5950
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Fri Nov 18 16:37:14 2011 |
steve | Update | VAC | preparing for ac power interruption |
The vacuum is ready for no AC power for 1 hr on Sunday morning at 10am
I did the follwing:
Closed V1, stopped the rotation of TP-1 maglev, waited till it reached 0 Hz_ rpm and turned it's controller off.
Closed V4 and stopped TP-2 rotating
Closed all annuloses and VA6
Closed VM1 and opened VM3 This means the RGA is being pumped by TP3. RGA is running in background mode. V5 will close instantly as the AC will be turned off.
VAC STATUS: IFO envelope and annulosses are not pumped. P1 pressure will reach 5-6 mTorr by Sunday morning.
The PSL output shutter will be closed by the interlock at 3 mTorr
Kiwamu will turn off Piezo Jena PZT power supplies and computers Saturday.
I will be here around 1pm Sunday to star pumping. I will need EPICs MEDM running by than. |
Attachment 1: planednopower.png
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10467
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Mon Sep 8 08:24:49 2014 |
Steve | Update | Computer Scripts / Programs | preparing vac system to reboot |
Q and Steve will follow elog 10028 entry to prepare the vacuum system for safe reboot |
10468
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Mon Sep 8 11:10:26 2014 |
ericq | Update | Computer Scripts / Programs | preparing vac system to reboot |
Quote: |
Q and Steve will follow elog 10028 entry to prepare the vacuum system for safe reboot
|
Here's the sequence of the morning so far:
- I aligned the IFO (IR arms with ASS, X green with PZTs, PRM with PRMI locked on REFL33)
- I closed the PSL shutter, and went inside to align PRM and both ITM oplevs (all others were within 10urad of zero in both directions)
- While aligning those oplevs, I noticed the smell of burnt electronics. We tracked it down to the +15V sorensen in the rack nearest the PSL table
- I claim the precipitating event was PSL shutter activity. If I recall correctly, the seismic rainbow traces went bonkers around the same time as the shutter was closed. There is a Guralp interface in the rack powered by the failed sorensen, so this would explain the erratic seismometer signals correlated with the power supply failure. We will look into potential shorts caused by the shutter. (Steve looked up the PMC trans and Guralp DQ channels, and confirmed the temporal coincidence of the events.)
- We shut off all of the sorensens so that electronics were not being driven asymmetrically.
- Steve and I secured the vacuum system for computer reboots, as referred to in Steve's elog. Some combination of Jenne, Rana and Manasa shut down the control room computers, and turned off the watchdogs.
- Manasa and I moved Chiara inside, next to Mafalda, along with its backup HDs. It has been labeled.
- Booted up control room machines, they came up happy.
- FB and front-ends didn't need reboot, for some lucky reason. Watchdogs came back happily, oplev spots didn't move noticeably.
The IFO is still down, as the PMC won't lock without the rack power, and we haven't pinned down the shorting mechanism. We don't want the replacement sorensen to immediately blow when plugged in. |
10469
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Mon Sep 8 11:34:47 2014 |
rana | Update | Computer Scripts / Programs | preparing vac system to reboot |
FYI: in that rack, the +15V pulls ~0.5 A more than -15V usually. I think this is due to some RF amplifiers which are powered by this (e.g. the AOM that Manasa set up). The Sorensen's can source ~30A in principle, so we should make sure to set the current limit appropriately so as to not overheat them when there is a short.
Was this power supply not fused for all of its connections? I remember that this was connected to at least one un-fused connection in the past year. |
10470
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Mon Sep 8 12:11:36 2014 |
manasa | Update | Computer Scripts / Programs | preparing vac system to reboot |
Quote: |
FYI: in that rack, the +15V pulls ~0.5 A more than -15V usually. I think this is due to some RF amplifiers which are powered by this (e.g. the AOM that Manasa set up). The Sorensen's can source ~30A in principle, so we should make sure to set the current limit appropriately so as to not overheat them when there is a short.
Was this power supply not fused for all of its connections? I remember that this was connected to at least one un-fused connection in the past year.
|
+15V supply powers the following (from what I see):
1. PMC and MC boards on the rack.
2. RF amplifiers on the rack for the beat signals from the green beat PDs.
3. Beatbox itself.
The beatbox was the one that had an un-fused connection last year. I re-did it properly to go through a fuse quite sometime ago.
I dont see any other un-fused connections now from the +15V supply right now.
P.S. AOM driver takes a 0 to +28V power supply and not connected to the +15V |
10477
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Tue Sep 9 14:18:40 2014 |
Steve | Update | Computer Scripts / Programs | preparing vac system to reboot |
Quote: |
Quote: |
Q and Steve will follow elog 10028 entry to prepare the vacuum system for safe reboot
|
Here's the sequence of the morning so far:
- I aligned the IFO (IR arms with ASS, X green with PZTs, PRM with PRMI locked on REFL33)
- I closed the PSL shutter, and went inside to align PRM and both ITM oplevs (all others were within 10urad of zero in both directions)
- While aligning those oplevs, I noticed the smell of burnt electronics. We tracked it down to the +15V sorensen in the rack nearest the PSL table
- I claim the precipitating event was PSL shutter activity. If I recall correctly, the seismic rainbow traces went bonkers around the same time as the shutter was closed. There is a Guralp interface in the rack powered by the failed sorensen, so this would explain the erratic seismometer signals correlated with the power supply failure. We will look into potential shorts caused by the shutter. (Steve looked up the PMC trans and Guralp DQ channels, and confirmed the temporal coincidence of the events.)
- We shut off all of the sorensens so that electronics were not being driven asymmetrically.
- Steve and I secured the vacuum system for computer reboots, as referred to in Steve's elog. Some combination of Jenne, Rana and Manasa shut down the control room computers, and turned off the watchdogs.
- Manasa and I moved Chiara inside, next to Mafalda, along with its backup HDs. It has been labeled.
- Booted up control room machines, they came up happy.
- FB and front-ends didn't need reboot, for some lucky reason. Watchdogs came back happily, oplev spots didn't move noticeably.
The IFO is still down, as the PMC won't lock without the rack power, and we haven't pinned down the shorting mechanism. We don't want the replacement sorensen to immediately blow when plugged in.
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Vacuum safe reboot required one hour of no pumping of the vac envelope. |
Attachment 1: v1closedfor1h.png
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11384
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Tue Jun 30 11:33:00 2015 |
Jamie | Summary | CDS | prepping for CDS upgrade |
This is going to be a big one. We're at version 2.5 and we're going to go to 2.9.3.
RCG components that need to be updated:
- mbuf kernel module
- mx_stream driver
- iniChk.pl script
- daqd
- nds
Supporting software:
- EPICS 3.14.12.2_long
- ldas-tools (framecpp) 1.19.32-p1
- libframe 8.17.2
- gds 2.16.3.2
- fftw 3.3.2
Things to watch out for:
- RTS 2.6:
- raw minute trend frame location has changed (CRC-based subdirectory)
- new kernel patch
- RTS 2.7:
- supports "commissioning frames", which we will probably not utilize. need to make sure that we're not writing extra frames somewhere
- RTS 2.8:
- "slow" (EPICS) data from the front-end processes is acquired via DAQ network, and not through EPICS. This will increase traffic on the DAQ lan. Hopefully this will not be an issue, and the existing network infrastructure can handle it, but it should be monitored.
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4567
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Mon Apr 25 22:38:49 2011 |
kiwamu | Update | LSC | prepration for DRMI : Y arm flashing |
This week is going to be a recycled Michelson week.
As a preparation I did several things today :
1. Alignment of the Y arm
2. Alignment of PRM
3. Checking of all the pick-off ports
(Y arm alignment)
The idea to have the Y arm aligned is that : once we lock the Y arm we will be able to align the input PZTs using the Y arm as a reference.
I tried aligning the Y arm and successfully made the Y arm flashing with IR. I can see it flashing on ITMY camera but no flashing on ETMY camera.
(PRM alignment)
PRM has been intentionally misaligned for the single arm green locking test.
I just confirmed that we can bring PRM back to a good alignment. Now we can see the central part is flashing too.
(picked-off beams)
I went checking through all the picked off beams to see if they are available or not.
POX : lost
POY : fine
POP : very clipped
POSRM : fine |
14247
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Fri Oct 12 17:37:03 2018 |
Steve | Update | VAC | pressure gauge choices |
We want to measure the pressure gradient in the 40m IFO
Our old MKS cold cathodes are out of order. The existing working gauge at the pumpspool is InstruTech CCM501
The plan is to purchase 3 new gauges for ETMY, BS and MC2 location.
Basic cold cathode or Bayard-Alpert Pirani
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5017
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Fri Jul 22 10:24:34 2011 |
steve | Update | VAC | pressure plot at day 213 |
Dec 21, 2010 we pumped down the MARK4 rebuilt 40m-IFO and the malev has been pumping on it since than |
Attachment 1: p.jpg
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5767
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Mon Oct 31 08:55:19 2011 |
steve | Update | VAC | pressure plot at day 53 |
Quote: |
I was lucky to notice that the nitrogen supply line to the vacuum valves was leaking. Closed ALL valves. Open supply line to atm. Fixed leak.
This was done fast so the pumps did not have to be shut down. Pressurized supply line and open valves to
"Vac Normal" condition in the right sequence.
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Attachment 1: pd71-m-d53.png
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13184
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Thu Aug 10 14:14:17 2017 |
Kira | Update | PEM | previously built temp sensor |
I decided to see what was inside the sensor that had been previously made. According to elog 1102, the temperature sensor is LM34, the specs of which can be found here:
http://www.ti.com/lit/ds/symlink/lm34.pdf
The wiring of this sensor confused me, as it appears that the +Vs end (white) connects to the input, but both the ground (left) and the Vout (middle) pins are connected to the box itself. I don't see how the signal can be read. |
Attachment 1: IMG_20170810_112315.jpg
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Mon Nov 14 21:22:48 2011 |
rana | Configuration | Computers | primetime RSYNC slowing down NODUS |
nodus:elog>w; who ; date
9:20pm up 44 day(s), 5:14, 5 users, load average: 0.29, 1.04, 1.35
User tty login@ idle JCPU PCPU what
controls pts/1 9:18pm 5 -tcsh
controls pts/2 2:37pm 6:39 25:02 25:02 /opt/rsync/bin/rsync -avW /cvs/c
controls pts/3 9:14pm w
controls pts/4 4:20pm 1:56 5:02 5:02 ssh -X rosalba
controls pts/8 8:23pm 47 4:03 -tcsh
controls pts/1 Nov 14 21:18 (pianosa.martian)
controls pts/2 Nov 14 14:37 (ldas-cit.ligo.caltech.edu)
controls pts/3 Nov 14 21:14 (rosalba)
controls pts/4 Nov 14 16:20 (192.168.113.128)
controls pts/8 Nov 14 20:23 (gwave-103.ligo.caltech.edu)
Mon Nov 14 21:20:48 PST 2011
we will ask the man to stop running backups at this time of night... |
3863
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Thu Nov 4 17:53:29 2010 |
yuta | Update | CDS | primitive python script for A2L measurement |
Summary:
I wrote a python script for A2L measurement.
Currently it is really primitive, but I tested the basic functionality of the script.
We already have A2L script(at /cvs/cds/rtcds/caltech/c1/scripts/A2L) that uses ezlockin, but python is more stable and easy to read.
A2L measurement method:
1. Dither a optic using software oscillator in LOCKIN and demodulate the length signal by that frequency.
2. Change coil output gains to change the pivot of the dithering and do step 1.
3. Coil output gain set that gives the smallest demodulated magnitude tells you where the current beam spot is.
Say you are dithering the optic in PIT and changing the coil gains keeping UL=UR and LL=LL.
If the coil gain set UL=UR=1.01, LL=LR=-0.99 gives you demodulated magnitude 0, that means the current beam spot is 1% upper than the center, compared to 1/2 of UL-LL length.
You do the same thing for YAW to find horizontal position of the beam.
Description of the script:
Currently, the script lives at /cvs/cds/caltech/users/yuta/scripts/A2L.py
If you run;
./A2L.py MC1 PIT
it gives you vertical position of the beam at MC1.
It changes the TO_COIL matrix gain by "DELTAGAINS", turns on the oscillator, and get X_SIN, X_COS from C1IOO_LOCKIN.
Plots DELTAGAINS vs X_SIN/X_COS and fit them by y=a+bx+cx^2.(Ideally, c=0)
Rotates (X_SIN, X_COS) vectors to get I-phase and Q-phase.
(I,Q)=R*(X_SIN,X_COS)
Rotation angle is given by;
rot=arctan(b(X_COS)/b(X_SIN))
which gives Q 0 slope(Ideally, Q=0).
x-intercept of DELTAGAINS vs I plot gives the beam position.
Checking the script:
1. I used the same setup when I checked LOCKIN(see elog #3857). C1:SUS-MC2_ULCOIL output goes directly to C1:IOO-LOCKIN_SIG input.
2. Set oscillator frequency to 18.13Hz, put 18.13Hz band-pass filter to C1:IOO-LOCKIN_SIG filter module, and put 1Hz low-pass filter to C1:IOO-LOCKIN_X_SIN/X_COS filter modules.
Drive frequency 18.13Hz is same as the previous script(/cvs/cds/rtcds/caltech/c1/scripts/A2L/A2L_MC2).
3. Ran the script. Checked that Q~0 and rot=-35deg.
4. Put phase shifting filter to C1:IOO-LOCKIN_SIG filter module and checked Q~0 and rotation angle.
fitler rot(deg)
w/o -35
+90deg 45
-90deg 56
-45deg -80
5. Put some noise in C1:SUS-MC2_ULCOIL by adding SUSPOS feedback signal and ran the script.(Attachment #1)
During the measurement, the damping servo was off, so SUSPOS feedback signal can be treated as noise.
Conclusion:
The result from the test measurement seems reasonable.
I think I can apply it to the real measurement, if MCL signal is not so noisy.[status: yellow]
Plan:
- add calculating coherence procedure, averaging procedure to the script
- add setting checking procedure to the script
- apply it to real A2L measurement
Bay the way:
Computers in the control room is being so slow (rossa, allegra, op440m, rosalba). I don't know why. |
Attachment 1: a2ltest.png
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