TITLE: 08/24 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: None
SHIFT SUMMARY: Commissioning work ongoing. Environment calm for now...
LOG: See attached
(Late post from yesterday. I must have never clicked submit.)
TITLE: 08/23 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: None
SHIFT SUMMARY: Commissioning ongoing. Wind has also picked up to 30mph gusts.
LOG: see attached
Taking advantage of an IFO lock loss today, I was able to enter the LVEA and connect high voltage cables (available IP6 cables) to the newly rebuilt 2500 L/s ion pump stored in the Beer Garden near the IP6 location. I then energized the rebuilt pump and confirmed that it works. I am leaving the cables connected to the pump but de-energized. We hope to install this unit at the IP2 location on Tuesday.
Stefan and Sheila turned on the ITMX ring heater yesterday from a number I calculated to balance the effective static lensing between ITMX and ITMY.
I trended the BNS range and PRC Gain right after turning on the ring heater (attached) and also looked at the DARM spectrum (attached) for a few times after turning on the ring heater.
It looks like the range goes up by the PRC gain does not, and the spectrum shows that the shot noise limited part of DARM doesn't get much better which is what you expect if the circulating power was actually improved. However, I'm not sure exactly if this is a calibration issue or if we're seeing the effect of the ring heater in a way we don't expect.
This is a backup note that several days ago, when I was working on the TEC servo for SHG and OPO, I found that the SHG TEC excitation was left on for a while (months)..
This can be related to the green power fluctuations, I turned that off, and we should make sure that excitation to be OFF.
It seems this happened due to the Beckoff crashed and restart, and the default of this switch is on, which Livingston may have the same situation for attention.
[Jenne, Hang, Gabriele]
We locked the full IFO, closed the corner ASC loops and the arm hard loops. We then moved common soft and differential soft to optimize the recycling gain. We also tuned the PRM angular set point.
We could increase the recycling gain from 31.6 at the beginning to about 37.3 at the end, so about 17% more recycling gain.
The blue hose used for cooling water for the 70-W amplifier is labeled (a bit hard to read) something like PUR-L 1154 D 8X6X1 SERIE 11-M-1Y (or maybe 11-14-17).
Apparently it is 8 mm OD, 6 mm ID. The hoses are about 3.5 m long.
Photos attached.
Sheila, Stefan - SRC2, the ASC_AS_C pointing loop using the right actuator combination of SR2 and SRM, was straight forward: gain of 20, integrator on, done. - For SRC1, we first dithered SRM in PIT and YAW to find the optimal spot. - Then we phased AS_A_RF72 in this configuration by putting all DC signal into the I quadrature, using the ezcaservo below. This naturally zeroed the Q_PIT and Q_YAW error signals. Both had decent sensitivity to the SRM. - So we closed the loops. Attached are some snapshots. - Note: There was no signal in AS_B_RF72. - I added everything to Guardian, but didn't test the engagement yet, so go slow through ENGAGE_SRC_ASC the next time. - Also SRC2 can probably take 20dB more gain (take out FM1), but we didn't bother for tonight. - Finally SRC1 can probably also run with higher gain, but at the current gain the FM2 integrator results in an overshoot because it fights with the SRM top mass integrator. - We then set the ringheater X to 0.28 Watt total (0.14 Watt each half-heater). The ASC system should take care of the alignment (except the SOFTies). - We left the IFO locked in that state for a stability check. The ezcaservo lines for phasing: ezcaservo -r H1:ASC-AS_A_RF72_Q1_MON -g -0.2 -f 1 H1:ASC-AS_A_RF72_SEG1_PHASE_R ezcaservo -r H1:ASC-AS_A_RF72_Q2_MON -g -0.2 -f 1 H1:ASC-AS_A_RF72_SEG2_PHASE_R ezcaservo -r H1:ASC-AS_A_RF72_Q3_MON -g -0.2 -f 1 H1:ASC-AS_A_RF72_SEG3_PHASE_R ezcaservo -r H1:ASC-AS_A_RF72_Q4_MON -g -0.2 -f 1 H1:ASC-AS_A_RF72_SEG4_PHASE_R
Jenne, Hang
We modified the old ASC sensing matrix code and did a measurement for the PIT dofs. The whole sensing matrix can be found at /ligo/home/hang.yu/Desktop/ASC/SenMtrx/rec/Aug232018225636UTC/html_rec_rad2W_1219100214.html. The calibration was based on some old scripts so we would need to double-check if they were still correct.
For now we just focus on the input-common arm dofs in PIT. For the three interferometrical dofs (currently we chose them to be INP1 -- > IM4, PRC2 --> PR2, and CHARD), the response matrix is
| REFL_A_RF9_I | REFL_A_RF45_I | REFL_B_RF9_I | REFL_B_RF45_I | POP_X_I | |
| CHARD | -0.56 | -0.96 | -0.44 | -1 | 0.15 |
| PRC2 (PR2) | 0.22 | -0.15 | 0.07 | -0.12 | -1 |
| INP1 (IM4) | 0.71 | 0.72 | -0.72 | -1 | -0.03 |
This suggested that we might update the input matrix to for better decoupling the dofs:
| REFL_A_RF45_I | REFL_B_RF45_I | POP_X_I | |
| 1 | 0.7 | 0 | CHARD |
| 0 | 0 | -0.05 | PRC2 |
| 1 | -1 | 0 | INP1 |
We didn't finish the yaw measurement and the AS port signals did not have a good coherence. Will update the drives when we get a chance next time.
All our violin frequencies have changed - in particular ETMX has moved up quite a bit (see alog 43331). The lowest frequency is 501.553HZ, and the highest frequency is 516.778Hz. So our frequency spread is about 3 times bigger than before. I designed new violin stop filters for DARM (DARM2 FM6,FM7,FM8): - The fundamental is now 6th order (was 4th). This gives similar phase at lower frequencies. - The 2f and 3f harmonic are wide enough to catch both actual violin modes and mathematical up-conversions (from possible DCPD saturations). - For the 4f and 5f I only cover the actual violin modes - they get too wide otherwise. The 6f again catches all of them. Note that the 5f and 6f (FM7) is usually not engaged.
Hang, Gabriele, TVo, Amber, Stefan, Danny
This morning we measured, using the AS_A and AS_B DC SUM, MICH dark and estimate 9 counts with 50 mW CO2 central heating on ITMY and 8000 counts for MICH bright (with no CO2) which leaves us with about 0.1% contrast defect.
We followed up the measurement by estimating the amount of sideband power we could be seeing :
Where P_f is the power of the sidebands of frequency f at the Michelson output, P_o is the input power to the Michelson, Gamma_f is the modulation depth of the sideband of frequency f, and t_f is the amplitude transmission coefficient of the sideband frequency f for the Michelson.
P_9MHz: 3.77*10^(-2) counts (0.4% of what we see when dark)
P_45MHz: 1.3 counts (14.4% of what we see when dark)
Hang and TVo also thought about low frequency movement of the beamsplitter and how this could introduce higher order misalignment modes. We looked at the power spectrum of the beamsplitter oplevs below 0.5 Hz and estimate 10*10^(-9) radians (in both pitch and yaw) is dominant at those frequencies. We estimate the amount of HOM misalignment mode that could be contributing:
Where P_o is the input power to the Michelson, alpha is the beamsplitter misalignment (in rad), w(z) is the beam size at the misaligned optic, and lambda is the wavelength of the carrier. (The factor of 2 is added to include both pitch and yaw)
P_HG01 = 14.4*10^(-2) counts (1.6% of what we see when dark)
The model for differential lensing in a single bounce Michelson contrast defect should be simple conceptually. After the beamsplitter, the phase change that the X and Y beams see is dominated by the prompt reflection off the HR surface of the ITM as well as the double passing static substrate lens from the compensation plate+ITM substrate.
Using the galaxy page numbers:
#### static lens for substrate and cp ITMXstat = -1/310812.+1/664100. ITMYstat = 1.7E-6-1/1392000. # Parameters work out the TCS settings for O2 [diopters/watt] RH_SUBdef = -9e-6 CO2_SUBdef = 6.23e-5 #alpha_co2 in my equation # Parameters for surface deformation RH_SURFdef = 9.91e-7 # ITMX and ITMY Radii of Curvature R_ix= 1940.3 R_iy= 1939.2
Converting this to the required ring heater power to get this effect is the along the same lines of logic but the ring heater will change the substrate (double pass) as well as the HR surface (single pass) and of course, because the ring heater is annular heating instead of central, we will want to try this on ITMX ring heater.
We can try to run the ring heater over the weekend as Sheila suggested and see if this improves the Michelson contrast over time. The loops that Hang and Gabriele designed seem to be stable enough to run for many hours.
Correction
The previous estimate of the actuation calibration for the CO2 lasers on the substrate was off by a factor of 3, this was due to the changing out the mask:
Old: 6.23e-5 diopters/watt
New: 2.50e-5 diopters/watt
So the estimate of the CO2 power for the best simple Michelson contrast defect is:
which still fits with our measurement.
Craig, Sheila
Craig moved pico motors on TMSX M14 and M4 (D1000484) so that the beams are now centered on the QPDs with our current alignment which gives a recycling gain of about 32.
I attempted to do this for the TMSY picos, but ran into some kind of bug.
The worst feature of this bug is that you can select a current motor, and it looks like you have selected it if you are looking at one of the single motor screens. In the screen shot attached I circled in red that the current motor is 3, but you can see from the green dots above motor 1 (these channels are actually readbacks of the LEDs on the controller, so they are reliable about which motor is the current motor).
However, if you opened the single motor screen and start clicking on the buttons to move the motor you will move the wrong pico.
I did this, moving M3 which is the steering to the green QPD by mistake. We unshuttered the green beam for the y arm, I tried to reset the pico, and then Craig and I reset the QPD offsets to zero the green WFS signals so that our green reference is still well set. After this the camera spot is in the reference location, as expected.
We have tried many combinations of pushing buttons to try to change which motor is enabled, but we can't change the led lights right now. We will try power cycling the controller next time we loose lock.
After a lockloss I went to EY to try power cycling the unit.
When I power cycled it I saw that the PD out LEDs on the shutter controller which is mounted right above the pico controller toggled. (Photo will be attached to this log). Jenne saw that the shutter also shut. This is related to bug 11354
After the power cycle I tried changing the current motor on the medm screen, and saw that the behavior wasn't changed. (on the medm screen, the current motor changed but the green circles which represent the leds on the controller didn't change.) However, the leds on the front panel of the controller actually do change. (So it is hard to say if I did actually move the wrong pico earlier this afternoon)
Next I logged into the beckhoff machine, and see that in the system manager the LED readbacks are wired as a group (1st screenshot), while at end X where the led readbacks are working correctly, each bit is wired individually (2nd screenshot). It seems like the mapping is that the first BOOL (MOTOR_X[1]) gets the value of the entire byte (it is currently 4, which would mean the 3 motor is on which is the current motor right now).
I think that we should re-wire this tomorrow and find a time to fit in a restart, so that we can center on this QPD.
I've added an FRS 11356
It looks like there are inconsistencies at both end stations. Screenshots attached.
Patrick, Sheila
We looked at some of the readback from the times when we were moving pico motors last night.
The first attached screenshot shows what happened at EY, where the wiring of the LED readback is incorrect. The selected motor channel is changing as we were requesting different motors, but the LED readback is indicating that the 1st motor was active the entire time. Based on what I saw when I went to the end station and looked at the lights I think that the LEDs were actually changing, and so the motor that I was moving was actually the one indicated by the selected motor channel most of the time. However, as you can see from the channel called MOTOR_1_Y_POSITION, the software was counting steps as if I was moving MOTOR_1. I think this must mean that somehow the software looks at the LED readbacks to decide which motor it is moving, but it doesn't enforce that the selected motor matches the readback of which motor is selected, which it should.
The second attachment shows a bug in a controller that we think is wired correctly in the system manager EX. Here Craig was walking motor 3 and motor 4 to center the beam on the TMS IR QPDs. However, sometimes when he clicked to select one motor, the selected motor chanel changed but the LEDs which read back the active motor didn't change. The software allowed him to move the motor anyway, but recorded the move as if the wrong motor moved.
We should do at least two things:
Fix the wiring in EY so that the LED readbacks work
Change the code so that if the selected motor doesn't match the motor that is readback as on from the LEDs the user gets an error and can't move the motor.
[LHO Commissioners]
We were able to fully transition to DC readout, and we sat there for about 1 hour, from 22:14:00 to 23:12:00 UTC on 23Aug2018. Very exciting! We are on the BNS range board with a small, but non-zero number!
Awesome! Congratulations everyone on the hard and extraordinary work to get to this point.
J. Kissel
Using the lock stretch that Sheila called out in LHO aLOG 43263, I gathered data that shows the new violin mode forest after we've replaced ETMX, ETMY, and ITMX (with ITMY been exposed to air for ~9 months, which undoubtedly also changes the violin mode frequencies). Attached are comparisons of the Fundamental (~500 Hz), 1st Harmonic (~1000 Hz), and 2nd Harmonic (~1500 Hz) DARM ASDs from O2 (after the July 2017 EQ) and this most recent lock stretch.
I've begun to update the LHO violin mode table (Violin_Mode_Table_v2) in prep for identification of this new forest. I've used the in-air data from LHO aLOGs 40525, 42180, 38857.
So far, I can identify 29 of the fundamental 32 modes, with a 2 mHz resolution. They're tabulated below (and not yet in the table), since I've not yet associated them with a test mass (though some appear to be "obvious" given the large separation).
In hopes to identify the mode Sheila calls out as the worst, I've pushed a 503.085 Hz filter to all new test masses, on MODE 1. This way when we do get a decent lock stretch, we can identify the mass "passively" by turning on the filter with some small gain, to see on which test mass we get action. As before, we'll started by assuming the mode is controllable by driving in Pitch.
| Frequency | Potential Match w/ in-air |
| 501.553 | IY |
| 501.628 | IY |
| 501.692 | IY |
| 501.755 | IY |
| 502.784 | IX |
| 502.909 | IX |
| 503.085 | EY / IY |
| 503.198 | EY / IY |
| 503.676 | EY / IY |
| 503.733 | EY / IY |
| 504.143 | EY / IY |
| 504.176 | EY / IY |
| 504.606 | EY / IY |
| 504.719 | EY / IY |
| 504.850 | EY |
| 504.889 | EY |
| 504.942 | |
| 505.077 | |
| 505.186 | |
| 507.360 | EX |
| 507.493 | EX |
| 508.844 | EX |
| 508.938 | EX |
| 510.714 | EX |
| 510.723 | EX |
| 511.180 | |
| 513.405 | |
| 516.678 | EX |
| 516.778 | EX |
In order to gather this data, I just used the standard violin mode templates from O2 (see LHO aLOG 37921), which are linked off of the VIOLIN MODE monitor MEDM screen.
Remember, we tried to separate the mode frequencies between test masses, and cluster a given test mass, to make them more easily identifiable (see E1700342, G1701332), but the reality of implementing such a system didn't work out as planned (an already minimal supply of fibers, few sets of fiber breakages, changes in frequency after welding and annealing, etc.). See some details in LHO aLOGs 41216, 40292, and 38965, but most my memory of the failure of the plan is verbal from telecons -- perhaps others can retrace the steps.
I have started adding some violin mode bandpass filters for ETMX, but have not had a change to test them out yet.
I added bandpass, +60, -60 degree phase shifts for 508.36 Hz, 508.844 Hz, 510.714 Hz and 516.678 Hz, in the filter banks under Mode2, Mode 11, Mode 12, and Mode 13 respectively.
The 503.085 Hz mode is on ITMY, and has been damped with the MODE1 filter, with -70 gain, no extra phase ( this can definitely be tuned in the future though), and feedback to pitch.
Note: This comment should have appeared after Georgia's comment below.
The link to the wiki page above isn't working. Here is a link : Violin mode table v2
504.891 Hz is on ITMX, can be damped with a gain of -3 and a phase of -60 degrees. (FM1 in ITMX mode 1 is a 50 mHz wide filter centered at 504.891, this is narrower than our other filters because there is a nearby mode at 504.953 Hz.)
Unfortunately it looks like we have two modes on ITMY that are only separated by 4 mHz. I was able to damp a mode at 501.629 Hz on ITMY with the same MODE4 filter Georgia used to damp the mode at 501.625Hz, but with a negative gain and +60 degrees of phase. I was suspicious that these could be the same mode, so I compared a spectrum with a resolution of 2 mHz from 2:42 UTC today (before Georgia damped ITMY) with the lock at 5:09 UTC, and it looks like they are actually two modes separated by about 4mHz. (Screenshot)
To deal with this, I created a filter called doublet in MODE4 which has 0dB of gain and a phase of -31 degrees at 501.624 and -3dB with -147 degrees at 501.628 Hz. A brave soul might be able to engage this filter with the bandpass that Georgia made earlier and no additional phase shift to damp both modes at once.
Edit: I got to try the doublet filter but it isn't very effective at damping the higher frequency mode which is rung up at the moment.
I also tried to damp 501.755Hz, but I don't think this is on ITMY. I copied my filter to ETMX MODE3, and tried 2 phases of pitch, but we lost lock before I could try yaw or longitudinal for ETMX.
I added a few more violin mode damping filters for ITMY. I promise I'll update the wiki table with this information soon.
The 503.198 Hz mode (MODE5) is on ITMY YAW, and was damped easily with -10 gain (haven't optimised any of the phases yet).
I tried to tackle the ITMY forest around 501.6 Hz but had trouble with cross coupling, accidentally ringing up neighbouring modes. I narrowed the filters and had some success damping
- The 501.625 Hz mode in pitch with a gain of 15 (filter bank MODE4)
- The 501.555 Hz mode in yaw with a gain of 20 (filter bank MODE6)
- The 501.692 Hz mode had some success with a gain of -5, before we dropped lock for other reasons. Will come back to it (filter bank MODE7).
J. Kissel
We don't yet have enough long lock stretches to get more precise than 0.005 mHz resolution, but I attach a few 1 mHz BW ASDs in the recent lock stretches that Sheila mentions (and some that I've found / reported),
- 2018-08-21 07:25 - 07:54 UTC,
- 2018-08-21 02:43 - 03:11 UTC,
- 2018-08-20 21:50 - 22:25 UTC,
- 2018-08-15 19:19 - 20:48 UTC,
where, because the last from several days ago, was 1.5 hrs, I was able to get a 0.5 mHz BW ASDs.
The message -- I can concur with Sheila's assessment that these two modes at 501.625 and 501.629 are 4 mHz apart -- however, only in 1 of the 4 measurements is the lower, 501.625 mode rung up. Thus, I think (thus far, we're not yet on DC readout) this is a weakly coupled mode that was rung up by our damping exploration attempts, so if we can design a filter that only tackles 501.629, then we might be OK. (It may not even be ITMY, but the 4 mHz mode separation does smell very much like a barely-elliptic mode splitting.)
I think Sheila and Georgia are on the right track of refining the band-pass filter to be that much more narrow. Mode frequencies for these violins are stable to temperature and test mass alignment at the ~10 microHertz level, so I think plant inversion -- or at least a very narrow (0.5 mHz) band-pass -- might be OK (see second attachment; figure 2 from G1601163 and/or G1700038).
Updated the table with some gains and phases for modes 504.606 Hz, 504.719 Hz, 504.85 Hz, all on ITMX and requiring low gains (<~5). And 504.953 Hz on ITMY (high gain, -30).
Posting this screenshot as a message to all the other v-modes out there. Blue reference is before damping, red is after.
In response to Sheila's request to compare the two following locks:
Aug 21 2018 02:42:00 UTC > Aug 21 2018 03:11:00 UTC [1218854538 > 1218856278]
Aug 21 2018 05:09:00 UTC > Aug 21 2018 05:29:00 UTC [1218863358 > 1218864558]
I ran 1mHz resolution PSDs. Results are below.
LOCK Aug 21 2018 02:42:00 UTC
Freq. [Hz] SNR
501.3750 77
501.5556 33815
501.6251 10114
501.6913 2815
501.6972 184
501.7553 181884
501.8750 76
502.7849 21376
502.9092 185016
503.0863 111095
503.1984 8470
503.6779 36286
503.7335 82344
504.1442 1609
504.1778 6259
504.6075 19039
504.7205 103589
504.8516 8474
504.8900 26733
504.9529 33514
505.0786 29540
505.1875 230981
507.3609 143884
507.4945 1342
508.8452 783438
508.9403 590
510.7142 915952
510.7255 268
511.1820 147617
513.4059 398372
513.5119 159
516.6806 693925
516.7800 5140
Lock Aug 21 2018 05:09:00 UTC
Freq. [Hz] SNR
501.5540 147
501.6293 478058
501.6925 2127
501.7553 612669
502.7849 17214
502.9091 183754
503.0860 50717
503.1984 88
503.6779 48336
503.7335 45705
504.1442 5292
504.1778 17130
504.6075 45363
504.7205 529860
504.8516 386988
504.8900 1223
504.9529 534100
505.0786 50532
505.1875 238858
507.3609 269516
507.4945 1032
508.8452 459774
508.9404 271
510.7142 492155
510.7254 108
511.1819 184454
513.4059 193424
513.5119 159
516.6806 423031
516.7799 4596
I am sorry I have just noticed these round of violin modes alog entries.
I will investigate further but as a quick comment to add to the comments above:
Jeff suggested that the frequency separation of 4mHz of the two modes may indicate frequency splitting of modes associated to the same fibre. However based on the data we have from all fibres of both LIGO detectors this is very improvable. Frequency splitting observed so far is on the order of tens to hundreds of mHz, there only one case of about 1mHz separation at LLO ITMX and it is not certain to be associated to the same fibre.