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.
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.
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 !
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.
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.
. 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
UTILITY & SERVICE INTERRUPTION
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.)
Interim Director of Campus Operations & Maintenance
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.
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.
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.
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).
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:
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.
I made another estimation assuming that PRCL RIN is caused by translation of the cavity axis:
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.
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.
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 email@example.com .
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
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.
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.
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):
$ (cd /opt/rtcds/caltech/c1/target/c1dnn/c1dnnepics && ./startupC1)
$ taskset -c 6 /opt/rtcds/caltech/c1/target/c1dnn/bin/c1dnn -m c1dnn
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:
I'm going to start testing cpuset offline to figure out exactly what would need to be done.
[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.
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.
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:
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/.
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.
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
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.
[ 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.
Chief Engineer, LIGO Laboratory
California Institute of Technology
MC 100-36, 1200 E. California Blvd.
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.
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)
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) Measurement of the arm lengths
(not yet) Alignment of the Y green beam (#5066)
(not yet) Measurement of the MC spot positions
The vent will start from 1 st of August !
Both arms locked easely around 1V transmited. We should recenter oplevs.
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.
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.
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:
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.
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
Vacuum safe reboot required one hour of no pumping of the vac envelope.
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:
Things to watch out for:
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
Dec 21, 2010 we pumped down the MARK4 rebuilt 40m-IFO and the malev has been pumping on it since than
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.
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:
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.
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
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.
Rotation angle is given by;
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.
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.
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]
- 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.
./A2L.py MC1 PIT
ITMX was drag wiped, and the suspension was put back into place. However, after removing all of the earthquake stops we found that the suspension was hanging in a very strange way.
The optic appears to heavily pitched forward in the suspension. All of the rear face magnets are high in their OSEMs, while the SIDE OSEM appears fine. When first inspected, some of the magnets appeared to be stuck to their top OSEM plates, which was definitely causing it to pitch forward severely. After gently touching the top of the optic I could get the magnets to sit in a more reasonable position in the OSEMs. However, they still seem to be sitting a little high. All of the PDMon values are also too low:
Taking a free swing measurement now.
Nic and I discovered a problem with the in-vac wiring from the feed-thru to the top of the table. Pin 13 at the top of the stack, which is one of the coil pins on the tip-tilt quadrapus cables, is *the* shield braid on the cable that goes to the feed-thru. This effectively shorts one of our coil signals.
There are three solutions as we see it:
* swap pin 13 for something else at the top of the stack, and then swap it back somewhere else outside of the vacuum.
* swap *all* the pins at the top of the table to be the mirror. We would then need to mirror our cables on the outside, but that's less of an issue.
* make a mirror adapter that sits at the top. This would obviously need to be cleaned/baked.
None of these solutions is particularly good or fast.
We clearly need a better plan for adjusting the tip tilts in pitch, because utilizing their hysteresis is ridiculous. Koji and Steve are thinking up a set of options, but so far it seems as though all of those options should wait for our next "big" vent. So for now, we have just done alignment by poking the tip tilt.
Tomorrow, we want to open up the MC doors, open up ETMY, and look to see where the beam is on the optic. I am concerned that the hysteresis will relax over a long ( >1hour ) time scale, and we'll loose our pointing. After that, we should touch the table enough to trip the BS, PRM optics, since Koji is concerned that perhaps the tip tilt will move in an earthquake. Jamie mentioned that he had to poke the tip tilt a pretty reasonable amount to get it to change a noticeable amount at ETMY, so we suspect that an earthquake won't be a problem, but we will check anyway.
I'm very unhappy with the tip-tilts right now. The amount of hysteresis is ridiculous. I have no confidence that they will stay pointing wherever we point them. It's true I poked the top more than it would normally move, but I don't actually believe it wouldn't move in an earthquake. Given how much hysteresis we're seeing, I expect it will just drift on it's own and we'll loose good pointing again.
And as a reminder, IPPOS/ANG don't help us here before the tip-tilts are in the PRC after the IP pointing sensors.
I think we need to look seriously at possible solutions to eliminate or at least reduce the hysteresis, by either adding weight, or thinner wire, or something.
The PSL/IOO combo has not been behaving responsibly recently.
The first attachment is a 15 day trend of the MZ REFL, ISS INMON, and MC REFL power. These show two separate problems--recurring MZ flakiness, which may actually be a loose cable somewhere which makes the servo disengage. Such disengagement is not as obvious with the MZ as it is with other systems, because the MZ is relatively stable on its own. The second problem is more recent, just starting in the last few days. The MC is drifting off the fringe, either in alignment, length, or both. This is unacceptable.
The second attachment is a two-day trend of the MC REFL power. Last night I carefully put the beam on the center of the MC-WFS quads. This appears to have lessened the problem, but it has not eliminated it.
It's probably worth trying to re-measure the MCWFS system to make sure the control matrix is not degenerate.
I've noticed several CDS problems:
Since the nodus upgrade, Eric/Diego changed the old csh restart procedures to be more UNIX standard. The instructions are in the wiki.
After doing some software updates on nodus today, apache and elogd didn't come back OK. Maybe because of some race condition, elog tried to start but didn't get apache. Apache couldn't start because it found that someone was already binding the ELOGD port. So I killed ELOGD several times (because it kept trying to respawn). Once it stopped trying to come back I could restart Apache using the Wiki instructions. But the instructions didn't work for ELOGD, so I had to restart that using the usual .csh script way that we used to use.
Same thing again today. So I renamed the /etc/init/elog.conf so that it doesn't keep respawning bootlessly. Until then restart elog using the start script in /cvs/cds/caltech/elog/ as usual.
I'll let EQ debug when he gets back - probably we need to pause the elog respawn so that it waits until nodus is up for a few minutes before starting.