Last week I found that megatron was still off after the power outage. Apparently, the power recovery checklist had not been followed during the recovery.
Please remember to use the checklist and post the checklist results after each power outage. Megatron is now on and functioning.
We have placed some sweet giant strawberries in the fridge; free for eating for anyone working in the lab today or tomorrow:
This is a common occurrence when diagnostic scripts are written without the ability to handle exceptions (e.g. ctrl-c, terminal gets closed, etc.).
The first thing to do is make sure that the "new" script you are writing doesn't already exist (hint: look in the old scripts directory).
If you are writing a script that touches things in the interferometer, it must always return the settings to the initial state on abnormal termination:
Its a good question, but the answer is yes. At some level all of the OL servos should be different to handle the different mechanical resonances of the suspension as well as the optical table's acoustic noise and the different noise requirements for the difference optical cavities.
However, it would be better to have the same basic structure and then one or two customization filters.
Set the PRM OL servo gains to zero until someone can take care of this. Turning off the buttons doesn't help anything if people run the alignment scripts.
That sounds goofy.
With the delay line technique, you can get a linear signal over 50 MHz with no phase shifting. What is with all this I/Q stuff?
You can easily calculate whether or not the coarse readout will work by thinking about the scan resolution you need given the ADC dynamic range and the whitening filter that you use.
Nice PSL summaries from LHO:
The MC waist is correct as is the arm RoCs. Most likely the error is in the telescope length or its distance from the MC. Jenne probably has all the numbers and can give us a surface plot showing how the MM degrades as a function of those two parameters.
Cycling the vacuum is easy. Why not vent starting Thursday evening and pop the doors on Friday morning? Inspect on Friday and pump on Monday morning.
Start pumping on Monday before Steve goes home.
As stephanie did a few years ago, the idea should be to match the damping between the DRMI optics so as to minimize the differential motion. No notching is necessary. Read her SURF report about the IMC.
I used APTITUDE to install texlive-full on rosalba so that I could work on a paper. pdflatex was not found on pianosa, rosalba, megatron, etc. I used this command:
sudo aptitude install texlive-full
While this was installing, I read a bunch of forums which claim that its better to bypass the apt-get and use the
TexLive installer instead so that we can use its own package updater 'tlmgr'. Otherwise, the standard Ubuntu distributions
are years out of date (e.g. doesn't have RevTex 4.1).
WE tried to use the new conlog today and discovered that:
1) No one at the 40m uses conlog because they don't know that it ever ran and don't know how to use regexp.
2) It has not been running since the last time Megatron was rebooted (probably a power outage).
3) We could not get it to run using the instructions that Syracuse left in our wiki.
Emails are flying.
Jenne, Den, Rana
The PMC transmission has been varying a lot and the MC seems unstable. Superstitious people might blame this on the El-nino or the alignment with Sagitarius, but we are ostensibly scientists.
WE found that the PMC EPICS values had not been toggled since the reboot and so the RF phase and Amplitude were totally wrong (we should replace this with a fixed oscillator box as we did with FSS).
Also, the NPRO SLOW slider was at -2 V which made the mode going into the PMC funny (although the mode was OK this morning before I started playing with the PMC sliders).
Before adjustment, there was a strong correlation between the seismic motions and the PMC reflection. This means that the PMC gain was low and it couldn't stay locked. Now, after fixing the RF and upping the gain slider it looks more stable. Let's watch it for a few days to see if there's an improvement in the trends.
The 10-minute trend of the lat 400 days shows that nothing has changed much this year; its been equally bad for a long while.
To get the code to run on c1pem1, we had to move the old target back into the /cvs/cds/caltech/target/ directory. It is in /cvs/cds/caltech/target/c1pem1/.
JoeB had apparently moved it into some other area called 'oldfe' and this was why the weather station has not been running for years. Joe is at LLO now, but he's not beyond our reach...
Once the code had been moved back I started it up. I also rebooted it from the telnet prompt to ensure that it worked on reboot. It did.
The cable issue that Liz mentions probably happened during the PSL table lifting and cable cleanup. It looks like someone yanked the ethernet cable out of its adapter and broke it...
If the problem is the precision in DTT, then why would the noise change when the corner frequency of the filter is changed?
And how about checking for filter noise in the situation we saw online? 4th order low pass at 1 Hz or 8 Hz.
You cannot use the digital system for this. You hook up a scope to the transmitted light as well as the incoming light (after the MC, perhaps at IP_POS). Then you acquire the data from both places simultaneously using an ethernet equipped scope. The step response of the PDs used for this has to be calibrated separately.
Sanwiched wall as shown: 1" clear acrylic, 2 layers of 0.004" thick "window tint", 1 layer of 0.007" thermashield and 0.125" yellow acrylic
Visibility: 70 %, Transmission of 1064 nm 2-3 % at 0-50 degrees incident power density 0.7 W/mm2
Max power 100 mW
Good. The power density and max power are not important (especially since you don't define a quantitative way to spec them). We ONLY care about the transmission.
Just felt an EQ. Impulse moved some vertical blinds by several mm.
Tue Aug 07 23:26:06 2012
Looks like you're just measuring the ADC noise. You should add ADC noise to your plot. To compare the geophones with the accelerometers, you have to correct for the preamp gain and plot them both in the same units.
To get above the ADC noise you can use an SR560 preamp. (AC Coupled, G = 100)
The PDA255 is a good ringdown detector - Steve can find one in the 40m if you ask him nicely.
I fixed up the seismic.stp file for the StripTool display:
0) Did a bunch of alignment to get beams roughly centered on ETMY and ITMY and maximize power. Adjusted the aperture and focus on ETMY camera to get nice image. Camera needs to be screwed in tightly and cables given some real strain relief, Steve.
1) snapshots not working on many MEDM screens. Who's on top of this?
2) save/restore not working for PZT2 sliders
3) changed power and filter triggers on yarm to match xarm
4) yarm filters copied from xarm (need to handtune RGs)
5) DTT wasn't working on rossa. Used the Date/Time GUI to reset the system time to match fb and then it stopped giving 'Test Timed Out'. Jamie check rossa ntpd.
6) Removed the high 3.2 Hz RG filter. We don't have any sharp features like that in the spectrum.
---then added it back. The 3.2 Hz comes and goes depending on what Yoichi is doing over in the MC area. Leaving it in by default, but lowering the Q from 2 to 1.5.
7) Attached is the noise spectra, coherence, and loop gain model for this yarm condition. For the plant model, I assume a pendulum (f=1 Hz, Q = 9) and a cavity pole of 1600 Hz. Gain is scaled to set the UGF at 165 Hz (as guessed by looking at the servo gain peaking frequency). This cheezy model doesn't include any of the delays from DAC, AA, or AI. Eric and Sasha should have something more useful for us by Friday.
8) Change the DQ channels: need XARM and YARM IN1 at 16k. e.g. XARM_ERR, etc.
9) To get the DTT plots to make thumbnails in the elog, I print a .ps file and then use 'epstopdf' to make the PDF.
The problem with the glow on the ETMY face is due to the red light being scattered off of the optical table from the HeNe laser for the OL. Why is the red light hitting the table?
One way to fix the problem for the camera image is to insert a long pass filter (if Steve can find one).
Edmund Optics: NT62-874
Edmund Optics: NT65-731
Edmund Optics: NT32-759
I've noticed that we're experiencing this bug which was previously seen at LHO. We cannot enter 10 digit GPS times into the time fields for DTT due to a limit in TLGEntry.cc, which Jim Batch fixed in September of last year. Seems like we're running an old version of the GDS tools.
I checked the Lidax tool (which you can get from the GDS Mainmenu). It does, in fact, allow 10 digit entries.
MC and PMC vis:
MC REFL Unlocked = 4.4
MC REFL Locked = 0.67
1 - Locked/Unlocked = 85%
PMC REFL Unlocked = 0.270
PMC REFL Locked = 0.013
1 - Locked/Unlocked = 95%
I checked (by looking through recent trends) that the zero level is zero on both channels. I tried to do a proper mode scan, but we have lost the PSL fast channels during the upgrade sadly. Also, the DC signal for the PMC REFL needs some gain. Unlocked level should be more like 3-5 V.
Also used the instructions from this page to add Google's sources to rosalba's apt-get list and then installed Chrome.
It is HIGHLY unlikely that the IMC mirrors are having any effect on the ringdown. The ringdowns take ~20 usec to happen. The mirrors are 0.25 kg and you can calculate that its very hard to get enough force to move them any appreciable distance in that time.
I found this entry in the old 40m ilog which describes the STACIS performance. It shows that even though the STACIS is bad for the differential arm motion below 3 Hz. It has quite a big and positive effect at 10-30 Hz. The OSEMs show a bigger effect than what the single arm does. I think this is because the single arm is limited by the MC frequency noise above 10 Hz.
We should figure out how to turn on the STACIS but set the lower UGF to be ~5 Hz.
I turned on some filters and gain in the SUS-MC2_MCL filter bank tonight so as suppress the seismic noise influence on MC_F. This may help the MC stay in lock in the daytime.
Koji updated the mcdown and mcup scripts to turn the MCL path on and off and to engage the Boost filters at the right time.
The attached PNG shows the MCL screen with the filters all ON. In this state the crossover frequency is ~45 Hz. MC_F at low frequencies is reduced by more than 10x.
I also think that this may help the X-Arm lock. The number of fringes per second should be 2-3x less.
On Friday, Koji and I adjusted the beam pointing into the DRMI using the PZT yaw and found that the beam inside the DRMI (as seen on the AS camera) looked OK (not distorted too much).
So it seems that the issue seen before, namely that the DRMI resonant mode is very strange, is no longer true.
The camera image at the AS port still looks elliptical. So Jenne and Mike have started to make this beam round by adjusting the lenses.
Our plan now is:
1) Fix AS camera optics to get a round beam (single bounce off of ITMY).
2) Flash DRMI to make sure the beam at AS is still round.
3) Using the moveable Watec camera and Sensoray, get images of the spot on all DRMI mirrors with DRMI flashing. Use targets and rulers whenever possible to get quantitative measurements of the beam positions. (i.e. just saying "Oh, its pretty much in the center" is the Mickey Mouse approach to science)
4) Align all pickoff beams in this situation. Make sure there is no in vac clipping. Align IP POS and ANG using this input beam pointing.
5) Pump down.
The PMC reflection made it seem that the beam going into it was misaligned. I went to the table and aligned the input beam to maximize the PMC transmission. I got ~10% improvement.
Just to check if something was loose, I started tapping things upstream of the Faraday. When I tapped the actual PMC body it seemed to get unseated and the reflected (unlocked) power jumped up by more than a factor of two.
I don't understand how this could be. The attached trend of the PMC channels shows that ever since the PSL upgrade, the PMC refl has been at the low level of ~0.3 V, except for a brief phase soon after the upgrade late in 2010 and then also for a few hours early in May of 2012.
If the PMC body actually moved, it seems that the pointing into the MC would also change and I don't see that. So what else can it be? Is there some clipping or dust or a burn spot on the PMC REFL path?
The PMC refl image was lost after the body re-settled itself. Jenne and I re-aligned it and added a 0.5 ND filter to the existing ND in order to account for the higher power. We should hide all of the reflective ND filters and just use absorbtive ND for the cameras to prevent reflections.
This image of the past hour shows the event at just before midnight (0650 UTC) where the PMC reflection goes up from 0.28 to 0.85.
After looking at the in-vacuum layout I think we should make two changes during the next vent:
1) Reduce the number of mirrors between the FI and its camera. We install a large silvered mirror in the vacuum flange which holds the Faraday cam (in the inside of the viewport). That points directly at the input to the Faraday. We get to remove all of the steering mirror junk on the IO stack.
2) Take the Faraday output (IFO REFL) out onto the little table holding the BS and PRM Oplevs. We then relocate all 4 of the REFL RFPDs as well as the REFL OSA and the REFL camera onto this table. This will reduce the path length from the FI REFL port to the diodes and reduce the beam clutter on the AS table.
Looks good. Any way that you can tell in an unambiguous way, where the beam is, is very good. Ideally we want to have1-2 mm accuracy.
This was in response to my suggestion to move the REFL beam path to the table containing the BS/PRM Oplevs. From this seismic data it is clear that the BS table is no worse than the AS table, so we should plan to make the layout change during the next vent.
My hope is that the DRMI flashes will be bright enough to see on the PO beams. IF we get 10 mW through the Faraday, you should get some buildup when the carrier resonates in the DRMI.
If the recycling gain is 10 and the pickoff fraction is 100 ppm you ought to get ~10 uW on PO. How much of the recycling cavity power gets out of POP?
Mannasa and Unni and I looked at the RF driver for the AOM. It was fine.
With the ALC input left unconnected, with the power supply set to +28V, it was drawing 0.56 A.
By adjusting the modulation input we were able to get 1.1 Vrms into the scope (terminated at 50 Ohms) after going through 2 10dB attenuators. 11 Vrms into 50 Ohms is 33.8 dBm ~ 2W.
The RF power trimpot on the front of the driver is now adjusted so that -0.31 to 0.69 V takes the driver output from off to 2W output at 80 MHz.
The previous distorted signal that Jan and Manasa saw was at a level of ~100 mVrms, which is ~0.5 mW of power. At this tiny drive level, the internal amplifier is not linear and is mostly putting out a signal at ~160 MHz.
We checked by putting a square wave into the modulation input that the RF power from the driver would indeed shut off with a time scale of ~20 ns. Manasa will add a picture to this entry. We are ready now to calibrate the transmitted power of the AOM v. the modulation input voltage and then to measure the step time of the AOM.
Remember: do NOT believe the spec sheet of whatever PD you are using. All commercial PDs are slower than they advertise. In order to measure a <1 us step time you must use a PD with a >50 MHz 'bandwidth'.
What was the reasoning / resolution of the POP forward/backward beam? Are we going to have the right beam for DRMI locking?
Changed the list of channels to be written to frames from having the IN1 suffix to OUT. Now we can load the calibration of the channel into the filter module and the DQ channel will be calibrated.
We should do this wherever possible so that our channels will have real calibrations associated with them.
Next we should up the rate at which the model runs up to 16 kHz so that we can record the microphones at 16 kHz. FM radio has information up to 20 kHz. AM radio goes up to ~8 kHz. We should be at least as modern as AM radio. How do we make the change? How do we make sure the FOTON file stays OK?
I have made some changes to the daily summary file to compensate. New files is /users/public_html/40m-summary/share/c1_summary_page.ini.
Based on the elog entries, I assume they have not been burtrestored...
Do you know how to burtrestore or restart slow machines?
Problems with Slow Machines?
I guess that the estimated state has the same low pass filter, effectively, that we use to low pass the feedback signal in SUSPOS. I wonder if there is an advantage to the state estimation or not. Doesn't the algorithm also need to know about the expected seismic noise transmission from the ground to the optic?
All oplevs need a little realignment, especially ETMY, which had it's lens removed (Rana has a Wall of Shame photo of this, which is why it was removed by him). Steve will look into this tomorrow, after he starts pumping.
There is no situation in which it is OK to install a mount like this. Steve had installed this flaky and shaky mount to optimize the beam size on the OL QPD.
Everyone in the lab should know better. Putting in something like this is just like sabotage - it creates extra noise in our interferometer in a sneaky way and just makes locking harder. All mounts for anything useful (including QPDs) must have highly rigid mounts.
Use the example from the PSL relayout: use the 3/4" steel mounts and the wide aluminum bases from Newport. No more art projects using home made mounting crap, Steve.
Absolutely hokey. What are our requirements for this RFPD? What are the power levels and SNR that we want (I seem to remember that its for 22 as well as 110 MHz)? Perhaps we can test an aLIGO one if Rich has one sitting around, or if the aLIGO idea is to use a broadband PD I guess we can just keep using what we have.
Since we upgraded the CDS system, I guess our ADC ranges have gone up but we never did anything to the OLs to match the ADC ranges. From Liz's daily summary page of the OL, I see this:
So we need a factor of 5-10 increase in the electronics gain (why isn't the BS SUM on there?). This might be accomplished in the head, but for the ones with whitening boards, might be better to do there.
(** add to Jamie's list of long term tasks **)
VENT NOW and FIX ALIGNMENT!
Too bad - I thought it would at least give a little damping. Since we want the viscous-like energy loss to be ~49x larger, we need to have the field modulation in the damper (not dumper) increase by ~7.
We have to change the sample rate and AA filter for the mic channels before going too far with the circuit design.
That's no good - we need BLRMS channels for many PEM channels, not just two. And the channel names should have the same name as they had in the past so that we can look at long term BLRMS trends.
Maybe we have already discarded this idea, but why not do the alignment without the MC?
Just lock the green beam on the Yarm and then use the transmitted beam through the ITMY to line up the PRC and the PZTs? I think our estimate is that since the differential index of refraction from 532 to 1064 nm is less than 0.01, using the green should be OK. We can do the same with the Xarm and then do a final check using the MC beam.
In this way, all of the initial alignment can be done with green and require no laser Goggles (close the shutter on the PSL NPRO face).