Kiwamu and Steve have started venting the 40m vacuum envelope.
centered oplevs at resonating cavities,
ITM references were set by green pointer from the ends by Koji,
closed PSL shutter and placed manual block into beam path,
checked jamnuts in locked positions on bellows,
turned HV off at PZT-Jena "steering mirror" power supply and OMC HV ps
checked particle counts,
switched oplev servos off,
set up N2 cylinder to start vent from 1e-6 Torr to 25 Torr,
have ~ 6 cylinders of instrument grade compressed air to bring envelope from 25 Torr to 760 Torr
All three cranes were wiped off today.
Kiwamu has completed the vent.
ITMX OSEM CONFIGURATION
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.
Vac- rack is powered back up. UPS first, than all other power switches from top to bottom of the rack, except Maglev
Manually started one by one TP2 and TP3 to accelerate to 50 KRPM
Brought up vac.control screen on lap-top at /cvs/cds/caltech/medm/c0/ve/VacControl_BAK.adl
V5 and VM3 were opened so TP3 can pump on the RGA
V4 was opened so TP2 can pump on the Maglev-TP1. The Maglev power was turned on and started acceleration.
The vac control screen positions indicators were checked for true position and annulies vent valves were opened.
RGA manual on/off switch was turned at the top of the RGA-head. Ubuntu copmuter was started at cc4 1.1e-6 Torr
The RGA communication was started with: ssh c0rga from control room
The rga-script was started ./RGAset.py This script turns on the filament, rs-232 and scan parameters etc
Vac -configuration: IFO-P1 at atm, RGA is pumped and running in background mode, all annulos at atm
RGA scan of rga-region only at day 18 This is the back ground of the rga with some calibration gas.
We changed the pointer on /cvs/cds/caltech/target/gds/bin/awgtpman from
Then killed the megatron framebuilder and testpoint manager (daqd, awgtpman), restarted, hit the daq reload button from the GDS_TP screen.
This did not fix everything. However, it did seem to fix the problem where it needed a rtl_epics under the root directory which did not exist. Alex continued to poke around. When next he spoke, he claimed to have found a problem in the daqdrc file. Specifically, the cvs/cds/caltech/target/fb/ daqdrc file.
set gds_server = "megatron" "megatron" 10 "megatron" 11;
He said this need to be:
set gds_server = "megatron" "megatron" 11 "megatron" 12;
However, during this, I had looked file, and found dataviewer working, while still with the 10 and 11. Doing a diff on a backup of daqdrc, shows that Alex also changed
set controller_dcu=10 to set controller_dcu=12, and commented the previous line.
He also changed set debug=2 to set debug=0.
In a quick test, we changed the 11 and 12 back to 10 and 11, and everything seemed to work fine. So I'm not sure what that line actually does. However, the set controller_dcu line seems to be important, and probably needs to be set to the dcu id of an actually running module (it probably doesn't matter which one, but at least one that is up). Anyways, I set the gds_server line back to 11 and 12, just in case there's numerology going on.
I'll add this information to the wiki.
Modified one of the PD assemblies carrying a large SI-Diode (~10mm diameter).
Removed elements used for resonant operation and changed PD readout to transimpedance
configuration. The opamp is a CLC409 with 240 Ohm feedback (i.e. transimpedance) resistor.
To prevent noise peaking at very high frequencies and get some decoupling of the PD,
I added a small series resistor in line with the PD and the inverting opamp input.
It was chosen as 13 Ohm, and still allows for operation up to ~100MHz.
Perhaps it could be smaller, but much more bandwith seems not possible with this opamp anyway.
Changes are marked in the schematic, and I list affected components here.
(Numbers refer to version 'PD327.SCH' from 30-April-1997):
-connected L3 (now open pad) via 100 Ohm to RF opamp output. This restores the DC sognal output.
-connected pin 3 of opamp via 25 Ohm to GND
-connected kathode of PD via 13 Ohm to pin 2 of opamp
-removed L6, C26, L5, C18, and C27
-shorted C27 pad to get signal to the RF output
Measured the optical TF with the test laser setup.
(Note that this is at 1064nm, although the PD is meant to work with green light at 532nm!)
Essentially it looks usable out to 100MHz, where the gain dropped only by about
6dB compared to 10MHz.
Beyond 100MHz the TF falls pretty steeply then, probably dominated by the opamp.
The maximal bias used is -150V.
If the bias is 'reduced' from -150V to -50V, the response goes down by 4dB at 10MHz and
by 9dB at 100MHz.
The average output was 30mV at the RF output, corresponding to 60mV at the opamp output (50Ohm divider chain).
With 240 Ohm transimpedance this yields 250µA photo-current used for these transfer functions.
The periscope design for beam elevation of the green beams is posted. The design for the 90 deg steering version is also coming.
(2010-03-29: update drawings by daisuke)
90deg version: http://nodus.ligo.caltech.edu:8080/40m/2725
Here the design of the periscope for the 90 deg steering version is posted.
straight version http://nodus.ligo.caltech.edu:8080/40m/2709
Steve and Koji
WE started to build 5 TTs. 4 of them are used in the recycling cavities. One is the spare.
We built the structure and are building the cantilever springs.
This evening we measured the noise spectrum of the reference cavity PD used in the FSS loop. From that we estimated the transimpedance and found that the PD is shot-noise limited. We also found a big AM oscillation in correspondence of the FSS modulation sideband which we later attenuated at least in part.
Some more words about the RFAM: I noticed that there was an excess RFAM by unlocking the RC and just looking at the RF out with the 50 Ohm input of the scope. It was ~100 mVp-p! In the end our method to minimize the AM was not so sensible - we aligned the waveplate before the EOM so as to minimize the p-pol light transmitted by the PBS cube just ahead of the AOM. At first, this did not minimize the RFAM. But after I got angry at the bad plastic mounting of the EOM and re-aligned it, the AM seemed to be small with the polarization aligned to the cube. It was too small to measure on the scope and on the spectrum analyzer, the peak was hopping around by ~10-20 dB on a few second timescale. Further reduction would require some kind of active temperature stabilization of the EOM housing (maybe a good SURF project!).
For the EOM mount we (meaning Steve) should replace the lame 2-post system that's in there with one of the mounts of the type that is used in the Mach-Zucker EOMs. I think we have spare in the cabinet next to one of the arms.
After the RFAM monkeying, I aligned the beam to the RC using the standard, 2-mirror, beam-walking approach. You can see from the attached plot that the transmission went up by ~20% ! And the reflection went down by ~30%. I doubt that I have developed any new alignment technique beyond what Yoichi and I already did last time. Most likely there was some beam shape corruption in the EOM, or the RFAM was causing us to lock far off the fringe. Now the reflected beam from the reference cavity is a nice donut shape and we could even make it better by doing some mode matching! This finally solves the eternal mystery of the bad REFL beam (or at least sweeps it under the rug).
At the end, I also fixed the alignment of the RFPD. It should be set so the incident angle of the beam is ~20-40 deg, but it was instead set to be near normal incidence ?! Its also on flimsy plastic legs. Steve, can you please replace this with the new brass ones?
I was aware of a problem on those units since I acquired the data. Then it wasn't totally clear to me which were the units of the data as downloaded from the Agilent 4395A, and, in part, still isn't.
It's clear that the data was in units of spectrum, an not spectral density: in between the two there is a division by the bandwidth (100KHz, in this case). Correcting for that, one gets the following plot for the FSS PD:
Although the reason why I was hesitating to elog this other plot is that it looks like there's still a discrepancy of about 0.5dBm between what one reads on the display of the spectrum analyzer and the data values downloaded from it.
However I well know that, I should have just posted it, including my reserves about that possible offset (as I'm doing now).
All the details and data will be included in the wiki page (and so also the results for AS55). Here I just show the comparison of the transfer functions that I measured and that I modeled.
I applied an approximate calibration to the data so that all the measurements would refer to the transfer function of Vout / PD Photocurrent. Here's how they look like. (also the calibration will be explained in the wiki)
The ratio between the amplitude of the 55Mhz modulation over the 11MHz is ~ 90dB
The electronics TF doesn't provide a faithful reproduction of the optical response.
In order to measure the transfer function of the RC cavity's foam, I've turned off the servo so that the room temperature noise can excite it.
The attached plot shows a step response test from 2 weeks ago. Servo is nominally still working fine.
I went to Ottavia, and tried running yum update. It was having dependancy issues with mjpegtools, which was a rpmforge provided package. In order to get it to update, I moved the rpmforge priority above (a lower number) that of epel ( epel -> 20 from 10, rpmforge -> 10 to 20). This resolved the problem and the updates proceeded (all 434 of them). yum update on Ottavia now reports nothing needs to be done.
I went to Rosalba and found rpmfusion repositories enabled. The only one of the 3 repositories in each file enabled was the first one.
I then added priority listing to all the repositories on Rosalba. I set CentOS-Base and related to priority=1. I set CentOS-Media.repo priority to 1 (although it is disabled - just to head off future problems). I set all epel related to priorities to 20. I set all rpmforge related priorities to 10. I set all rpmfusion related priorities to 30, and left the first repo in rpmfusion-free-updates and rpmfusion-nonfree-updates were enabled. All other rpmfusion testing repositories were disabled by me.
I then had to by hand downgrade expat to expat-1.95.8-8.3.el5_4.2.x86_64 (the rpmforge version). I also removed and reinstalled x264.x86_64. Lastly I removed and reinstalled lyx. yum update was then run and completed successfully.
I installed yum-priorities on Allegra and made all CentOS-Base repositories priority 1. I similarly made the still disabled CentOS-Media priority 1. I made all epel related repos priority 20. I made all lscsoft repos priority=50 (not sure why its on Allegra and none of the other ones). I made all rpmforge priorities 10. I then ran "yum update" which updated 416 packages.
So basically all the Centos control room machines are now using the following order for repositories:
CentOS-Base > rpmforge > epel > (rpmfusion - rosalba only) > lscsoft (allegra only)
I'm not sure if rpmfusion and lscsoft are necessary, but I've left them for now. This should mean "yum update" will have far fewer problems in the future.
I've added a new page in the wiki which describes the current naming scheme for the .mdl model files used for the real time code generator. Note, that these model names do not necessarily have to be the names of the channels contained within. Its still possible to make all suspension related channels start with C1:SUS- for example. I'm also allocating 1024 8 byte channels for shared memory address space for each controller and each simulated plant.
The wiki page is here
Name suggestions, other front end models that are needed long term (HEPI is listed for example, even though we don't have it here, since in the long run we'd like to port the simulated plant work to the sites) are all welcome.
I've just now re-enabled the temperature control of the reference cavity can. Trend of the last 8 days is attached.
My attempt to passively measure the transfer function of the foam failed fantastically.
As it turns out, the room temperature fluctuations inside the PSL box reach the 1 mK/rHz noise floor of the AD590 (or maybe the ADC) at ~1-2 mHz. Everything at higher frequencies is noise.
So to see what the foam is doing we will have to do something smarter - we need a volunteer to disable the RC temperature servo from the EPICS screen and then cycle the PSL table lights every hour in the morning.
We'll then use our knowledge of the Laplace transform to get the TF from the step responses.
more detailed instructions needed....
We've turned off the RC temperature stabilization and the lights will supply the quasi-random heat input to the table and the cavity. Alberto and Kiwamu will be turning the lights on and off at random times.
The attached plot is the spectrum of temperature fluctuations of the room and the vacuum can with no stabilization from this weekend. I think the rolloff above 10 mHz is kind of fake - I had the .SMOO parameter set to 0.99 for both of these channels. I've just now set the .SMOO to 0 for both channels, so we should now see the true ADC or sensor noise level. It should be ~1 mK/rHz.
On Friday, I deleted a bunch of filters from the c1susvme2 optics' screens (MC1,2,3 + SRM) so as to reduce the CPU load and keep it from going bonkers.
This first plot shows the CPU trend over the last 40 days and 40 nights. As you can see the CPU_LOAD has dropped by 1 us since I did the deleting.
In the second plot (on the right) you can see the same trend but over 400 days and nights. Of course, we hope that we throw this away soon, but until then it will be nice to have the suspensions be working more often.
I modified the /etc/rc.d/rc.local file on megatron removing a bunch of the old test module names and added the new lsc and lsp modules, as well as a couple planned suspension models and plants, to shared memory so that they'll work. Basically I'm trying to move forward into the era of working on the actual model we're going to use in the long term as opposed to continually tweaking "test" models.
The last line in the file is now: /usr/bin/setup_shmem.rtl lsc lsp spy scy spx scx sus sup&
I removed mdp mdc mon mem grc grp aaa tst tmt.
I modified /cvs/cds/caltech/target/fb and changed the line "set controller_dcu=10" to "set controller_dcu=13" (where 13 is the lsc dcu_id number).
I also changed the set gds_server line from having 10 and 11 to 13 and 14 (lsc and lsp).
The file /cvs/cds/caltech/fb/master was modified to use C1LSC.ini and C1LSP.ini, as well as tpchn_C2.par (LSC) and tpchn_C3.par (LSP)
testpoint.par in /cvs/cds/caltech/target/gds/param was modified to use C-node1 and C-node2 (1 less then the gds_node_id for lsc and lsp respectively).
Note all the values of gds_node_id, dcu_id, and so forth are recorded at http://lhocds.ligo-wa.caltech.edu:8000/40m/Electronics/Existing_RCG_DCUID_and_gds_ids
Let me remind you how to lock and align the IMC
1. Open the doors for the IMC/OMC chambers. Open the manual shutter of the PSL just in front of the optical window
2. Run scripts/MC/mcloopson
3. Set the MC length path gain 0.3 / Set the MC total gain "+20"
4. If you want to avoid excitation of the mirrors by air turbulence, put a big plastic film and put three posters on the top and both the sides on the floor to block the wind go into the chamber.
To shut down
1. Run scripts/MC/mcloopsoff
2. Close the manual shutter, Remove the wind blockers, and the light door of the chambers
To align the MC
1. Tweak MC2 and MC3 to get maximum transmittion and/or minimum reflection.
ETMY-south sus damping was restored
As we learned yesterday, the PSL laser power out put mechanical shutter is not working in the remote mode. It only works in local manual mode.
Do not rely on the MEDM screen monitor readout! The position is only changing on the monitor. The main beam must be blocked before the output periscope.
Ben found the Sorenson 5V ps off. It was turned off since our last scheduled power outage. I wonder what else is running on 5V in the PSL? This power supply should be on the
"alarm handler" list to avoid future repeat of this condition. However a real safety switch would have confirming position sensors of the shutter open or closed. Is there such thing at the sites?
Yesterday Steve and I revived two legs to mount some optical breadboards outside of the end table.
These legs had been used as oplev's mounts many years ago, but now they are served for 40m upgrading. These are really nice.
By putting them on the side of the end table, a mirror mounted on the top of the leg can reflect the beam outside of the end table.
Once we pick off the green beam from the end table to its outside, the green beam can propagate through the 40m walkway along the Y-arm.
So that we can measure the beam profile as it propagates.
These legs are also going to be used during mode matching of the vacuum optics.
[Jenne, Kiwamu, and Steve via phone]
Around 9:30pm, Kiwamu and I came back from dinner, and were getting ready to begin the beam scan measurements. I noticed that one of the vacuum pumps was being very loud. Kiwamu noted that it is the fore pump for TP3's turbo, which he and Steve replaced in January (elog 2538). We had not noticed these noises before leaving for dinner, around 8pm.
We called Steve at home, and he could hear the noise through the phone. He said that even though it was really loud, since it was reading 3.3mTorr (on the display of the controller, in the vacuum rack just above head-height) which is close to the nominal value, it should be fine to leave. He will check it out in the morning. If it had been reading at or above ~1Torr, that's indicative of it being really bad, and we would have needed to shut it off.
For future reference, in case we need to turn it off, Steve said to use the following procedure:
1. Close VM3, to isolate the RGA, which is what this pump is currently (while we're at atmosphere) pumping on. I don't know if there are other things which would need to be shut at this stage, if we were at vacuum nominal.
2. Close VM5, which is right in front of TP3, so TP3's pump is just pumping on itself.
3. Push the "Stop" button on the Turbo controller for TP3, in the vacuum rack, about waist level. Turning off the turbo will also turn off the fore pump.
UPDATE, 1am: The controller in the rack is reading 3.1mTorr, so the pump, while still noisy, still seems to be working.
The foreline pressure of TP3 is 2.9 mTorr The drypump is loosing it's bearing and it is very noisy.
V3, V5 closed and TP3 small turbo controller off. This turned off the noisy forepump that has to be replaced.
RGA is running at cc4 2e-6 Torr
The RGA was turned off at cc4 1e-5 Torr
Bob replaced the tipseal in an other drypump and I swapped it in. TP3 turbo is running again, it's foreline pressure is 40 mTorr. The RGA is still off
IFO room temp 27.5C , Please remember to turn AC back on !
We should completely turn off the air conditioner when working on green locking.
Even if green beams propagates inside of chambers, the air conditioner does affect the spatial jitter of the beam.
The attached picture was taken when Steve and I were seeing how the green beam jittered.
At that time the beam was injected from the end table and going through inside of the ETM, the ITM and the BS camber.
Eventually it came out from the camber and hit the wall outside of the chamber. It was obvious, we could see the jittering when the air cond. was ON.
The second sideband is resonant in the arms for a cavity length of 37.9299m.
The nearest antiresonant arm lengths for f2 (55MHz) are 36.5753m and 39.2845m.
If we don't touch the ITMs, and we use the room we still have now on the end tables, we can get to 37.5m.
This is how the power spectrum at REFL would look like for perfect antiresonance:
And this is how it looks like for 37.5m:
Or, god forbid, we change the modulation frequencies...
The mode cleaner is locked and the air conditioning is full on. So the the air conditioning doesn't seem to be so important for the lock to hold.
Two days ago I opened the PSL shutter by switching the switch on the shutter driver. That caused the shutter's switch on the medm screen to work in reversed mode: open meant closed and closed meant open.
I fixed that. Now the medm screen switch state is correct.
I checked the effect of the arm length to the reflectance of the f2(=5*f1) sidebands.
Conclusion: If we choose L_arm = 38.4 [m], it looks sufficiently being away from the resonance
We may want to incorporate small change of the recycling cavity lengths so that we can compensate the phase deviation from -180deg.
f1 of 11.065399MHz is assumed. The carrier is assumed to be locked at the resonance.
Attachment 1: (Left) Amplitude reflectance of the arm cavity at f2 a a function of L_arm. (Right) Phase
Horizontal axis: Arm length in meter, Vertical Magnitude and Phase of the reflectance
At L=37.93 [m], f2 sidebands become resonant to the arm cavity. Otherwise, the beam will not be resonant.
Attachment 2: close-up at around 5 f1 frequency.
The phase deviation from the true anti resonance is ~0.7deg. This can be compensated by both PRC and SRC lengths.
i added my laptop's mac address to teh martian at port 13 today.
No personal laptop is allowed to the martian network. Only access to the General Computing Side is permitted.
Please disconnect it.
FSS SLOWDC slider is at around 0.
Please someone relock this at ~-4.0 to exploit some last juice of the fruit.
See this entry for the details of the operating point.
[Steve, Kiwamu, Jenne]
The 40m is now back in Laser Hazard mode. Safety glasses are required for entry into the LVEA / IFO room.
The insects and the laser trouble... Strange coincidences with LHO surprised me, but now I have been relieved.
Kiwamu, Nancy, and I restored the power into the MC today:
We found many dis-assembled Allen Key sets. Do not do this! Return tools to their proper places or else you are just wasting everyone's time!
Slow pump down _pd68 has reached the vacuum normal state. CC4_Rga region is pumped now. The RGA is still off.
Precondition to this pump down: 129 days at atm, ITMs replaced. MMT, oplev and other components were removed from BSC, ITMCs. New MMT mirrors are in. IOO_access_connector was out. The end chambers were not opened.
I also removed two of the AM stabilizers from the 1Y2 rack. The other one, which is currently running th MC modulations, is still in the rack, and there it is going to remain together with its distribution box.
I stored both AM stabilizers and the Stochmon box inside the RF cabinet down the East arm.
Rana found out that a connection was bad in the shown place, due to which the MEDM screen was showing bad offset for length control.
Basically, the offset slider value would not go into the system because of that bad connection, and was locking the mode cleaner at the wrong location.
We gave the Zonet camera the IP 192.168.113.26 and the name Zonet1.
We did this by modifying the /var/named/chroot/var/named/113.168.192.in-addr.arpa.zone and martian.zone files on linux1 as root.
I have resurrected the MC WFS on Friday night.
I have uncommented the WFS part of the MC autolocker.
The WFS total gain was empirically set to 0.1 such that the loops have no instability.
The loops somewhat worked through the weekend although they seemed to have the drift of the operating points
in accordance with the WFS spot.