Lost lock at 10:27 UTC. Cause unclear. Almost back to NLN.
TITLE: 03/24 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 67Mpc
OUTGOING OPERATOR: Jeff
CURRENT ENVIRONMENT:
Wind: 6mph Gusts, 4mph 5min avg
Primary useism: 0.02 μm/s
Secondary useism: 0.37 μm/s
QUICK SUMMARY:
No apparent issues.
Shift Summary: In Commissioning mode at start of shift. One Commissioning Lockloss. Relocking the IFO took a couple of tries. Robert ran the fire pump (WP #6529) while LLO was down. Back to Observing after Robert finished fire pump test.
A2L Pitch is well below the reference; Yaw is up to about 0.7
There is still a bit of noise in 20 to 50 Hz, which is moving the range around. Other than this, the rest of the shift passed without difficulty.
Back up and Observing after commissioning work finished. When we first locked the noise between 20 and about 100 Hz was bouncing around and keeping the range suppressed. It has subsided and the range is back up around 67 to 71 Mpc. All good at this time.
Bubba called - The tumbelweed balers are finished on the X-Arm for the evening. Work will resume tomorrow morning, probably around the LSB.
Daniel, Keita, Richard, TJ, Kiwamu,
We found that the newly installed harmonic generator (35033) had different relative RF phase than the previous for all the harmonic frequencies with respect to the seed frequency 9 MHz (as pointed out by Daniel, 35038).
This impacted on interferometer's sensing demodulation phases at several places, making us unable to lock the interferometer.
We spent almost all the working hours today retuning the relevant demodulation phases. After retuning them, we managed to get back to full lock.
[Adjustment of demodulation phases]
See the attached SDFs for a summary of the changes. Here is a list of the demodulation phases that we changed today.
Even though we could have tuned ASC-AS_B_RF36, we decided not to do this today. According to ASC-AS_A_RF36 which needed to change its demodulation phase by -23 deg, a sensible thing to do is to rotate the AS_B as well by the same amount. However, because AS_B_RF36 is not in use in full lock and is used only for lock acquisition which went smoothly without changing the demodulation phase, we don't bother it for the moment.
REFL27 was adjusted by minimizing the PRCL contribution in its Q phase. REFL135 was adjusted by minimizing the SRCL component in its Q phase. The 2f signals (18 and 90 MHz) were adjusted to maximizing the amplitude in their I phase when the DRMI was kept locked with both arm cavities held at a off resonance point. ASC-AS_ARF36 was adjusted by minimizing the BS contribution in to its I phase.
[Adjustment of 3f input matrix]
As we adjusted the demodulation phases, we also went through checking the input matrix for the 3f signals for holding the DRMI. We have changed the REFL27I -> PRCL gain from -4.0 to -2.0 and the REFL27I -> SRCL gain from 0.6 to 3.2. The former was adjusted to match the optical gain of REFL9I and REFL27I by exciting PRM at 30 Hz with 10 counts. The latter was adjusted by minimizing PRM coupling into the SRCL signal with an excitation on PRM at 30 Hz with a 10 counts.
These changes are implemented in the ISC_DRMI guardian.
[Electronics measurement and some phase madness]
In addition to these adjustments, Keita, Richard and I went to the CER and measured the relative RF phase between the old harmonic generator unit and the new one for each harmonic frequency using an RF analyzer. With this measurement we attempted to determine the required demodulation phase changes before actually changing the demodulation phases ini the digital system. However this didn't really work out for the following reason.
We brought the old unit to the CER with us and powered it up right next to the newly installed unit. We then split the 9 MHz seed via an RF distribution amplifier into two and fed each of them to each harmonic generator unit. Then we measured the relative phase and amplitude of all harmonic pairs (e.g. 18 MHz from the old unit v.s. 18 MHz from the new unit). However, as it turned out later, the RF distribution amplifier had random relative phase between the outputs. This, of course, screwed up our assumption that the input of the two harmonic generators were synchronized in their phases. Since we didn't measure the relative phase between the two seed signals, the measurement helped only for figuring out the demodulation phases associated with the 45 MHz family.
Nonetheless, I post the measurement results here for the record.
| phi_new - phi_old | amplitude_new / amplitude_old | |
| 18 MHz | - 93 deg | -0.7 dB |
| 27 MHz | -19 deg | -9.0 dB |
| 36 MHz | 72 deg | -3.3 dB |
| 45 MHz | 103 deg | -1.6 dB |
| 90 MHz | 98 deg | -1.2 dB |
| 135 MHz | -21 deg | -2.0 dB |
Note that this measurement was performed before we changed the RF attenuates (35045).
TITLE: 03/23 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: Jeff
SHIFT SUMMARY: The RF45 fixing and aftermath took the entire shift. Kiwamu, Keita, and Richard worked hard and they think we are fully recovered. Commissioning has begun and will continue for another 2 hours.
LOG:
Balers started around 19UTC near MX and are working their way toward the corner station. I still see them on the Xarm.
Keita, Kiwamu, Dave:
h1asc awgtpman stopped accepting new excitations. This is a special version of the awgtpman code with a higher maximum number of testpoints.
For now I stopped the special version and started the standard RCG version of awgtpman of awgtpman_h1asc
Shifter: Beverly Berger
LHO Fellow: Evan Goetz
Summary:
Details may be found at https://wiki.ligo.org/DetChar/DataQuality/DQShiftLHO20170320.
Large issue with the Harmonic frequency generator. working on fixing it. Not sure if swapping of the system will fix it.
Commissioning activities are being held off until we are sure we can relock. Today's commissioning time is most likely canceled due to this problem.
Went through old maintenance activities, and added new ones to the white board.
Current items:
Went over some wanted commissioning items. Some tasks are listed on the board next to the maintenance items.
CIT property management here next week.
WP6538 MX INSTAIR channel removal from cell phone alarm texter
Dave:
The vacuum alarm system on cdslogin was reconfigured to remove the channels : H0:VAC-MX_INSTAIR_PT399_PRESS_PSIG and H0:VAC-MX_INSTAIR_PT399_PRESS_PSIG_ERROR
I took the opportunity to reboot cdslogin to install patches.
yesterday I reduced the number of tasks crontab does daily at 04:02 on h1hpipumpctrley from eight to just one (log file rotation). Plot shows the PRESS1 signal, second trends, five minute duration 04:00 - 04:05 PDT. Left is Wed 3/22 (before change) right is this morning 3/23. As can be seen, glitch/spike has been fixed. I'll open a work permit to propagate this change to the other two units.
After a night of wasted science, (45Mhz Glitches) the Harmonic Frequency generator was swapped. Hopefully this was the culprit causing the glitches in the RF45. Serial number S1000796 was replaced with S1000798 Work Permit 6537
RF demodulation phases for 2f, 3f, 4f, 10f and 15f might change with this swap.
Replace Attenuator on: Freq Value with 18MHz +3 +2 27MHz +6 +2 36MHz +5 +4 45MHz +2 +1 91MHz 137MH No change. To keep the input value at 10dbm. Values based on Epics readbacks.
Tagging DetChar. We've recovered nominal low noise after this swap -- how ever we're seeing a lot of different behavior within this first few minutes: - Some line features below 100 Hz are reduced - There is elevated 500 Hz rising as f (like shot noise) noise floor - Occasional comb in a similar region - 4-5 kHz ratty hump that comes and goes - incredible amount of omega glitch above 500 Hz Just letting you know to keep your eyes peeled that this swap may mean several significant changes to the IFO that we may have to continue to rectify and/or deal with.
Upon entering the control room, I noticed that we have a low frequency oscillation in the PRC gain, POP DC, etc. on our front wall striptool. Turns out, this is the same as what Jim documented last night in alog 34999, and likely comes from Sheila's changing of the oplev damping cutoff in alog 34988.
I would like to go back to the old 10 Hz cutoff that we used to have in the oplevs, to see if that fixes this. However, Sheila noted to me that the old cutoff is zero history, no ramp, so we can't just go out of Observe and switch filters. I'll need to change the filters to always on, few sec ramp, load the filters, then we can switch back.
[Jenne, Sheila]
Hmmm. Reverting the cutoff frequency filters did not fix the problem. We're leaving them with the old 10Hz filters for now.
We also tried lowering the oplev gains by a factor of 8 on all test masses at the same time (in factor of 2 steps), but that caused CSOFT to start being unhappy, so we put them back to nominal before we lost lock.
We're going to go back to Observe since we don't have another idea right now of how to fix this.
As a note, it looks like this is upconverting with the 36Hz Cal lines to broaden them significantly, which is probably part of the reason we're at a reduced range right now.
Still no clever ideas, but it certainly seems like ITMY's oplev or something in the suspension is suspicious, and perhaps imposing noise through the ASC on the other optics. All 4 test masses see the 0.43 Hz oscillation in pitch, but ITMY seems to have many harmonics and other "hair" in the oplev spectrum. Not plotted, but ITMY yaw also sees the 0.43 Hz motion, but the other optics don't seem to see yaw problems.
EDIT to add spot position plot - spots on the test masses aren't moving very much over the last month, so it doesn't seem to be related to that. (Except ETMX yaw - still no idea why that's so scattered)
Beverly, Andy
On 22 Mar, a line of glitches at about 3.3 kHz appeared in apparent coincidence with these ASC problems. A known, always present line at the same frequency shows glitching at about 0.43 Hz (see attached spectrogram). A previous alog (27488) referred to this line as an SRM mode at 3335 Hz. In fact, the SRM spectrum (see attached spectrum) developed a feature at 0.43 Hz on 22 Mar that was not present on 21 Mar.
We haven't checked out anything related to Beverly's suggestion yet since the 0.43 Hz hasn't seemed to be a problem in the last ~day, and we've had other things to worry about. But, Sheila's 8Hz oplev cutoffs were in the guardian, so other than the lock that I had changed them back to 10Hz, they've been on the 8Hz cutoffs.
The DARM spectrum is noticeably better below about 25Hz, so it's good that Sheila's new oplev cutoffs aren't causing any problems, and are just helping.
Nothing outstanding to report. Everything looks normal.
Agreed, everything looks normal.
Everything looks normal with these trends.
I analyzed the HWS data for the lock-acquisition that occurs around 1173641000. The "point source" lens appears very quickly (within the first 60s) and then we see a larger thermal blooming over the next few hundred seconds. I've plotted the data below (both gradient field and wavefront OPD). There are a few obviously errant spots in the HWS gradient field data. Since I'm still getting used to Python, I've not managed to successfully strip these off yet. However, it is safe to ignore them.
Check out the video too. Next step is to match a COMSOL model of thermal lensing with a point absorber to the data to get a best estimate of the size of absorber and the power absorbed (preliminary estimates are of the order of 10mW).
FYI: this measurement compares the system before, during and after a lock-acquisition (ignore the title that says "lock-loss"). The previous measurement, 34853, looked at lens decay before, during and after a lock-loss.
For your amusement I've attached a GIF file of the same data. My start time is 79 seconds prior to Aidan's "current time".
The integrated gradient field data for H1ITMX is contained in the attached MAT file. It shows the accumulated optical path distortion (OPD) after 2.75 hours following the lock acquisition around 1173640800. This is the total accumulated OPD for a round trip through the CP+ITMX substrates, reflection off ITMX_HR and back through ITMX+CP substrates.
Note: this image is inverted. In this coordinate system, the top of the ITM is at the bottom of the image.
Here is the wavefront data with the superimposed gradient field. The little feature around [+30mm, +20mm] does not appear in the animation of the wavefront or gradient field over much of the preceeding 2.75 hours. My suspicion is that this is a data point with a larger variance that the other HWS data points, rather than a true represtation of wavefront distortion.
I fitted, by eye, a COMSOL model of an absorber (14mm diameter Gaussian, ~25mW absorbed) to the measured HWS data. I then removed this modeled optical path distortion to get the following residual (lower left plot). I then fitted a COMOSL model of 30mW uniform absorption to this model and subtracted it to get the residual in the lower right plot.
Here's the total fitted distortion from the sum of two COMSOL models (point absorber + uniform absorption):
