https://ldas-jobs.ligo-wa.caltech.edu/~lockloss/index.cgi?event=1401508133
Wind was brutal today, so I was messing with the controls on the BSCs to try to help. Mostly just running RX/RY sensor correction from St1 to St2 on the BSCs. Sensor correction is focused on improving the ~.4hz motion and doesn't really affect the motion outside that. I don't think this really helped, winds calmed down after I left at 5:30 and Ryan is almost all the way NLN now, so I will leave the extra sensor correction running for tonight. I'll accept SDFs for tonight, then turn it back of during maintenance tomorrow.
Wind and lock losses make a comparison challenging, but the blrms trends show the (log scale) improvement ETMY sees when it's turned on over .3-1hz. Top trace is the St2 RX GS13 blrms, middle trace is the gain for the sensor correction, sc is on when it's 1, off at 0. Bottom trace are the .3-1hz ground blrms. For the las 3-ish hours the St2 RX motion is lower with the sensor correction on even when the ground is moving more in this frequency band.
These changes were reverted today, in case they were causing issues with locking. ASC was engaged at the time, I didn't see any effect turning this stuff off, so I think they were probably benign.
I replaced the temporary covers on all viewports that I have opened with permanent covers.
TITLE: 06/03 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Wind
INCOMING OPERATOR: Ryan C
SHIFT SUMMARY: Still working on relocking and at LOCKING_ALS. We recently had gotten up to CARM_OFFSET_REDUCTION.
LOG:
14:30 Detector Observing and Locked for 6 hours
15:27 Lockloss https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=78202
- PSL ISS diffracted power low, so I moved REFSIGNAL up by 0.01
- Having issues locking ALS because of the wind picking up
- 10 locklosses from LOCKING_ALS
- 1 lockloss from FIND_IR
16:18 Holding in DOWN for a bit
16:28 Starting to relock again
- 3 locklosses from ALS
16:35 Back to DOWN - going to have to sit here for a while
- Some maintenance tasks are going to be done
17:59 Trying relocking again again
- Lockloss from CARM_150_PICOMETERS
- Lockloss from POWER_10W
- (many) locklosses from LOCKING_ALS
- Lockloss from CARM_150_PICOMETERS
20:21 Put in DOWN
21:49 Retrying relocking
- Lockloss from CARM_OFFSET_REDUCTION
| Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
|---|---|---|---|---|---|---|
| 15:20 | FAC | Karen | VacPrep, OptLab | n | Tech clean | 15:52 |
| 15:53 | FAC | Karen | MY | n | Tech clean | 17:23 |
| 15:54 | PEM | Robert | EX | n | Bringing back injection equipment | 16:04 |
| 16:08 | FAC | Kim | LVEA Receiving | y | Grabbing garb | 16:11 |
| 16:08 | PEM | Robert | LVEA | yes | Setting up tests | 17:55 |
| 16:09 | PCAL | Tony | PCAL Lab | y(local) | Starting measurement | 18:17 |
| 16:20 | FAC | Kim | MX | n | Tech clean | 16:55 |
| 16:31 | PCAL | Rick | PCAL Lab, OptLab | y(local) | PCAL work | 18:18 |
| 16:43 | TCS | TJ, Robert | LVEA | yes | Check out TCS electronics | 17:58 |
| 16:44 | PSL | Jason, RyanS | CR | n | Touch up PMC alignment | 17:28 |
| 16:52 | EE | Fil | LVEA | yes | Checking out failed dust monitor cables | 17:58 |
| 17:31 | ISC | Sheila, Jennie | CR | n | bounce measurements | 18:17 |
| 17:36 | Terry | OpticsLab | y(local) | SHG | 18:31 | |
| 19:18 | PEM | Robert | LVEA | yes | Taking photos | 19:35 |
| 20:15 | VAC | Travis | MY | n | Picking up parts | 20:28 |
| 21:05 | TCS | TJ | LVEA | yes | Putting terminator on output | 21:15 |
| 21:31 | Terry | OpticsLab | yes(local) | SHG | 22:24 | |
| 21:46 | AC | Gerardo | LVEA | yes | Checking work | 22:03 |
| 23:00 | PEM | Robert | LVEA | yes | Mounting an accelerometer | 23:51 |
Captured spectra for ranges at 140Mpc to 155Mpc, as well as the spectra after SR3 aligment changed to 83 from 438.
Reference point are labeled. The file is saved at /ligo/home/karmeng.kwan/DARM_trace.xml
DARM spectra was captured from H1:CAL-DELTAL_EXTERNAL_DQ
No clear differences seen between the spectra before and after the SR3 alignment change.
The comparison of the spectra shows the excess noise at 20-25Hz regime contributes to range drop, for both the original alignment and after SR3 alignment change.
Jennie W, Sheila
Jeff reminded me that we should notch out the bounce mode from the ASC MICH loops wich also feedback to the beamsplitter if we are correcting its notch in the LSC loops as per this entry.
The filter module I used was FM9 in ASC-MICH_P and Y. This is the orginal contents for MICH_P and this is it for MICH_Y. I checked the guardian code and neither of these were used in ISC_DRMI or ISC_LOCK guradians currently.
I copied the filter design from the LSC loop but without the roll mode notch at 25Hz as this was not in the ASC MICH loop already and we might want to tune this later if we can see it in DARM.
I tuned the magnitude to make it 0dB at high and low frequency. The filter design is here and the plot is here for pitch. And the same filter design and plot for yaw.
I don't have an OLG measurement to verify this mode shows up in ASC-MICH but Sheila pointed out that the ASC MICH loops are lower bandwidth than the LSC MICH loops so we shouldn't lose too much phase margin with this filter.
These new filters are saved and loaded in the ASC model coefficients but we will not test them till our next commissioning period.
I dove a bit further into the H1:TCS-ITMX_CO2_ISS_CTRL2_OUT_DQ channel correlating with our range drops on some days in May (alog78089). Robert and I also went onto the TCSX table and confirmed that the AOM is unplugged and that there were no other obvious culprits there on table. I added a 50 Ohm BNC terminator to the AOM as an excissive precaution and also moved some of the disconnected BNC cables on top of other cables to keep them from contacting the table directly. We also got Fil and had him look in the CER at the related chassis just in case.
Shown in the attached screen shot, the channel in question is ahead of an open switch (#1 & #2 are the CTRL2 outputs shown in medm and the electronics drawing - D1300015). #3&4 are the switch and #5&6 are the CTRL1 which doesn't see this same noise that CTRL2 sees during the range drops. The source of the extra noise must somehow be introduced somewhere from the open switch to the CTRL2 channel. In epics, I only see it in the CTRL2 channel. Interstingly, on May 17 the TCSX laser lost lock and the CTRL2 channel had an odd glitch 4 seonds before (2nd attachment).
Talking with Fil we might try disconnecting some of this at the AA chassis or swapping with TCSY to see if the problem moves with the chassis. In favor of not losing the one channel we have that connects some of our range loss, we might try swapping the chassis first.
TITLE: 06/03 Eve Shift: 2300-0800 UTC (1600-0100 PST), all times posted in UTC
STATE of H1: Wind
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
SEI_ENV state: CALM
Wind: 29mph Gusts, 21mph 5min avg
Primary useism: 0.06 μm/s
Secondary useism: 0.21 μm/s
QUICK SUMMARY:
03: 09 UTC back to Observing
With the difficulties locking, I tried changing some of the CPS diff filters to get the end station ISI to follow the corner ISI. The CPS diff uses a band pass filter to reduce the differential motion between the ISI, but this filter can inject motion at the microseism. Microseism is low, I'm guessing the arms are struggling more with the below .1hz motion. In the attached image the filters we had been using, are the red trace, blue is what I switched to. It kind of seemed to help, but I think we lost lock after I left the room. I'll leave this running for now, going to try a couple other things.
These changes were reverted today, in case they were causing issues with locking. ASC was engaged at the time, I didn't see any effect reverting to the old configuration, so I think they were probably benign.
Sheila, Jennie W
Sheila and Annamaria realised we have a noise bump around 17.75 Hz and hypothesised it could be the bounce mode of the beamsplitter which we have not retuned since adding the BRD (bounce-roll mode dampers) on the beamsplitter.
The LSC-MICH loop feeds back to the beamsplitter.
The measurement of the MICH loop is shown in this plot where it has a UGP 5.87Hz and phase margin of 35.5 degrees.
Code was adapted from Sheila's in this alog and is saved in /ligo/home/jennifer.wright/Documents/Filter_Design/plot_noise_OLG.py - although we are not sure if uncertainty estimates are accurate and the measurement is low coherence below 6Hz (near the UGP).
Sheila looked through the guardian and realised that we don't use FM8 in locking so we will overwrite the 15Hz notch here. Therte is an existing BRD bandpass in FM10 with this shape, which is used in locking, we don't want to overwrite this at the moment but we might once we test the new filter.
I copied over the FM10 filter to FM8 and then made it a bit wider to match the width of the bounce mode in the DARM spectrum found in this measurement from the 8th May.
The new filter is here and has this shape. We made it always on with a ramp of 4s and it is called BR0604.
I reloaded the LSC model coefficients (twice because I forgot to change the filter name the first time).
We will not test it till our next commissioning period.
Wind is above 40mph and we are trying to relock. We were able to make it up to POWER_10W a bit ago but then lost lock.
R. Short, J. Oberling
While H1 was down this morning from wind, we took the opportunity to touch up PMC alignment and recalibrate the rotation stage. With the ISS off, we used the two picomotor-controlled mirrors to increase PMC TRANS from 106.0W to 106.2W and decrease PMC REFL from 21.4W to 20.9W. Not much of an improvement here, unfortunately, so we think this lines up with our theory of increased loss in the PMC cavity (discussed in alog78093). We're now starting to think about swapping the PMC with our fresh spare during a future maintenance period, especially if we see this loss getting worse, but no plan is currently set for that just yet.
After turning the ISS back on, I proceeded to recalibrate the rotation stage since the output from the PMC has changed a couple of times in the past week with our alignment changes. Calibration curve, SDF screenshot accepting new values, and text file from the process are attached.
| Power in (W) | D | B (Minimum power angle) | C (Minimum power) | |
| Old Values | 102.287 | 1.990 | -24.825 | 0.000 |
| New Values | 99.253 | 1.990 | -24.830 |
0.000 |
https://ldas-jobs.ligo-wa.caltech.edu/~lockloss/index.cgi?event=1401411781
Back into Observing at 02:03
It looks like since this lock started, LSC MICH had been slowly getting louder (attachment1). Ground movement was low and wind was below 20 mph. On the test mass glitch/saturation side, the lockloss was seen by ETMX L3 first (attachment2).
Andrei, Sheila
We've analyzed the time-traces of the effective range (H1:CDS-SENSMON_CAL_SNSW_EFFECTIVE_RANGE_MPC) along with the alignment channels FC_WFC_A(B) and AS_A(B)_RF42 (see attached figures). We found no observable dependance between those.
During the time period being investigated in this alog on May 27, LASSO flags H1:TCS-ITMX_CO2_ISS_CTRL2_OUT_DQ as strongly correlated with the range. This channel and other related channels have been flagged as highly correlated to the range in recent days, but this time period shows the strongest correlation.
Jumps in this TCS channel correlate with range jumps, as shown in the attached comparison of the TCS and range trends on May 27.
Tagging TCS
This TCSX ISS correlation is a bit odd since we aren't using the ISS and the AOM, I believe, is completely unplugged. That said, I looked at some of the channels in that system and there is some extra noise seen around the times Derek posted (see May 16th example). I wonder if this points to a larger grounding issue or some other electrical problem that is seen more broadly.
These range fluctuations that we think are related to the squeezer started (I think) on May 16th: 77869
The first time cursor in the attached screeshot shows that range drip which I thought was traffic related at the time. Looking at the long term trend of this CO2 ISS control signal, there is a chance in charachter at this time, with more drifts in the signal level since. The second screenshot shows that this channel had a large jump on May 17th around 20:04-22:33 UTC.
There is a DARM BLRMS that may be more useful for tracking this noise than just looking at range, H1:OAF-RANGE_RLP_3_OUTPUT. (third screenshot shows this also had a change point and drifts more since May 16th.)
Minhyo
Tried move the beam on OMC QPD using single bounce beam (ITMX misaligned). Changed OM3 PIT & YAW from 18:04:45 UTC (gps: 1398534729).
- Tried same task with OM3, with turning off ASC centering, OMC centering, started new from 18:21:00 UTC (gps: 1398536470).
After finishing with OMC QPD, reverted all settings with OM3 and then moved to OM2.
- Moved OM2 PIT&YAW to check ASC-AS_A & B. Finished at 18:35:00 UTC (gps: 1398537318)
Same job was done (moving OM3 -> OM2) with SQZ beam on OMC (from 20:12:05 UTC to 20:24:00 UTC, gps:1398543158-1398543858)
Screenshots (ndscope) are: 1) Measurement with single bounce beam, 2) Measurement with SQZ beam
Summary of OMC-QPD profile measurement
Qualitative comparison of beam profile between single bounce (SB) beam and squeezer (SQZ) beam, arriving at the OMC-QPD. These measurement are done by comparing PIT and YAW response with OM3 movements. PIT and YAW response at around the center is expected to be inversely proportional to the beam diameter.
The valid data of each beam can be obtained
1) SB: 18:08:00 ~ 18:19:48 (UTC) -- with WFS centering on
2) SQZ: 20:12:00 ~ 20:18:00 (UTC) -- w/o WFS centering (mistake)
Since AS_C centering was off, it would be not perfect data, but judging from those measurement, SQZ beam is smaller than the SB beam. The
Below table is showing the relative ratio between SB and SQZ, with PIT and YAW individually.
| QPD A | QPD B | |
| PIT | 14.4% | 25.3% |
| YAW | 30% | 31% |
Added screenshots of comparison: 1) PIT comparison, 2) YAW comparison
Red lines are the plots that applied with the low-pass filter, and dashed lines are linear fitted lines in the range of (-1, 1) for both PIT and YAW.
Minhyo, Keita
As the PIT response on both QPD A and B are noisy, Keita and I checked for the source of that noise. By looking at multiple channel (1st screenshot), we found that ASC-AS_C PIT is also showing large noises.
Keita checked on the witness sensors of the mirrors before ASC-AS_C, and found out that beam splitter (BS) mirror is also showing large oscillation at around the SB measurement time (2nd screenshot). Checking with the ITMX(Y) status, it seems that BS is noisy after making single bounce (SB) beam condition.
After checking with the power spectrum data of SUS-BS_OPLEV_PIT_OUT_DQ (3rd screenshot), we noticed that the noise is higher during the SB measurement under 10 Hz, which is also showing large coherence with ASC-AS_C_PIT. We still don't know the exact origin of this noise, but it have definitely affected the beam's PIT movement beyond BS.
Minhyo, Keita
(Accidently didn't write alog about this, so I'm posting this in the comment)
We tried to measure the beam diameter that falls onto OMC-QPD (T1000276). The theory is to use the center gap of QPD as a calibration source, measuring the QPD SUM output data can give the information about the beam radius, since the power loss will occur due to the center gap in the QPD. It is expected that the SUM output will be minimum at the center, and gradually increase in respect to the offset from the center of QPD.
The measurement was done with single-bounce (SB) beam condition, during 2024-03-19, 18:30:00 ~ 19:30:00 (UTC). At first, we tried to center the beam by using SR2, AS_C centering loop and WFS centering. After that, tried to center the beam with using OMC servo with mastergain=0.1. The actual measurement time is in between 19:04:30 ~ 19:22:00 (UTC), and moved OM1 and OM2 manually, to move the beam off from the center (1st figure).
However, by checking on H1:ASC-OMC_A(B)_SUM_OUT16 channels, it didn't show the trend what we were expected. In almost all times, the power output showed consistent trend, and QPD A even showed highest value around the center of QPD (2nd, 3rd figure). Whereas, WFS sensor (AS_A and B) showed the expected increasing trend of power in respect to the offset from the center (4th figure), even though they are using same photo diode model.
From discussion, we suspect two origin for the descrepancy from the expected trend; 1) The center gap of QPD model (InGaAs-Q3000) is different from the cataloue (0.045 mm), 2) Quantum efficiency of QPD is not consistent in near the edge of each quadrant diode.
In conclusion, the quatitative measurement of beam profile of OMC using the center is limited due to the uncertainty of the QPD.
Attached figures are: 1) Visualization of the beam movement and power in each OMC-QPD, 2) Time series data of QPD channels, 3) OMC-QPD SUM_OUTPUT data in respect to the offset from the center, 4) WFS (AS_A and B), and AS_C OUTPUT data in respect to the offset from the center
Back to Observing at 05:19UTC