We have noticed that h1guardian0 is running slowly. It has a load average of 45, which is oversubscribed for a 12 core machine. Jamie has been contacted.

What: L2 Damp Mode Filters rung up and tripped the analog watchdog.

Where: mode 2 and mode 4, UR coil, 504.9HZ

We see some bursts of noise broadly around 200 Hz (first plot - you may need to squint a bit). I guessed that this was due to non-stationary coupling with SRCL, a la Gabriele. The second plot is a coherence spectrogram for the same five minutes. The coherence is indeed changing in bursts. The third plot is the coherence with MICH, PRC, and SRC over the same time. The coherence with MICH especially is extremely high; I think I saw that the feedforward is disabled?

We noticed that the violin modes were very rung up in the DARM spectrum on the wall causing a huge comb of peaks.  Kissel turned off the DARM ERR DAMP filters (violin mode filters) on all 4 TMs to see if that will help.  We did not toggle the intent bit - too busy trying to save the lock.

J. Kissel, M. Landry

More detailed aLOGs to come, but for those watching we've now completed all the tests we plan to do today with hardware injections and calibration measurements as of ~19:45 UTC / ~12:46 PDT. The observation intent bit is on. For the record, the "nominal" guardian state is still set to be "LSC_FF," (STATE_N = 520) but we will *not* be going to that state for not, as we still believe the MICH and SRCL subtraction are unstable and/or cause non-gaussianity. Also the cut-off filters for the CHARD and DHARD ASC loops are not engaged (because those also have not been tuned for the new higher recycling gain). We are leaving it in this state (called LOWNOISE_ESD_ETMY, STATE_N = 515) for this lock stretch, even though guardian does not think it's "nominal."  

Thanks for your patience!

For the record, the first part of this lock stretch was glitchy (as seen on the spectrum in the wall and in the time series of DARM control). We're not sure why, but we'd convinced ourselves that it did not directly correlate with our hardware injection tests. It would be interesting to know what the problem was,

Since DC lock was achieved at 11:09 (after starting to try locking at 9:00 this morning), I've set the intent bit to Undisturbed. Injections are ongoing, the range isn't great and there have been earlier lock losses, but for now I think we can call an official start to the mini-run at LHO.

Now locked for the mini run, I've updated the susdrift mon to capture this lock alignment.

This morning I noticed that the SRM SDF rwas reporting some errors which I (nor Kissel) have seen before, see attached picture.  Toggling the LOAD table and CONFIRM buttons did not clear the error.  Will talk to Dave/Jim...

Posted below are the data files for the two Dry Box cabinets in the VPW. No issues were noted in the April data.

Note: DB2 and DB3 are not in use at this time. Did not post data for these two cabinets.

With help from Richard McCarthy this morning, I was able to place the work platform on the stands allowing access to the BSC-1 annulus ion pump.

Seemingly the same symtom as ysterday (alog 18123). I did exactly the same recovery process. It is now back up and running.

Jeff K, Kiwamu, Jim W,

As a prep for the mini run, we aimed to confirm that we can run in the low noise state. Most of the attemps were successful today and the interferometer stayed at a recycling gain of more than 35 most of the time and 39 at one point.

Here are items that we could not get done today:

• MICH and SRCL feedforwarding
• DHARD and CHARD roll off filters
• High PSL power (we stayed at 2.7 W)
• Closing ITM alignment loops using the transmon QPDs
• Decent DARM open loop measurement

Also, an earth quake hit us at around 8:20 UTC which we think is from Papua New Guinea at around 8:06 UTC with 7.1 M. This is a good execuse to go home for the night.

(ITM camera position updated)

As planned yesterday (alog 18125), we did initial alignment from scrach. We started from the classic dither-based TMS alignment which gave us well-centered beam on ITMs. Then ITMs and ETMs were manually aligned to obtain high build up in the arm cavities for the green light. After this arm alignment, we updated the ITM camera positions. Moreover, we did the Y arm red/green co-alignment again. We started from BS alignment using the ETMY baffle (see for example alog 18035) and optimized ITMY and ETMY to get high build up in red. Then steered TMSY and green QPD pointing to maximize the green transmitted light. I introduced offsets of -0.2 and 0.2 counts in QPD_A_YAW and QPD_B_YAW respectively. Note that these QPD offsets were confirmed to be good afterwords with the interferometer fully locked and optimized for high recycling gain.

The full-scratch alignment seemed to have helped increasing the recycling gain and therefore we did not have an issue in reducing the CARM offset which was very problematic yesterday seemingly due to a poor recycling gain (alog 18125). Once we fully locked the interferometer, we maximized the recycling gain by manually steering both ITMs in pitch and yaw as usual. This resulted in a recycling gain of 39 acrroding to TRX and TRY. The camera positions were then updated again for the high recycling gain condition. Also, I updated the ITMY aperture which I disabled two days ago (alog 18108) because the aperture was basically not doing a good job at all. I attach a picture of the ITMY camera with the new aperture masking. This seems to be working fine so far.

(Some udpates on ISC_LOCK guardian)

Since we have been focusing on the recycling gain issue in the past days, many commands (e.g. ASC roll offs (alog 17966) and etc.) had been commented out in ISC_LOCK which had helped the interferometer staying robust. However for the automation purpose for mini run, I uncommented all the commented lines in ENGAGE ASC so that now it engages all the loops. So far we did not see an issue with these ASC loops except for the DHARD/CHARD roll offs which apparently make the loops unstable for some reason. They remain uncommented. Also, I kept the roll mode damping commands commented out because I am worried about a situation where the modes rang up so high that the damping signals saturate the DACs. We increased the DARM offset from 2x10^-5 to 3x10^-5 counts in order to obtain more light on the OMC DCPDs. This gave us a total current of 10 mA when PSL was at 2.7 W.

After we edited the guardian, we confirmed that the ISC_LOCK could take us up to the low noise ETMY ESD state. This is a step far from the final state, the LSC feedforward. We did not get a chance to check out the LSC feed forward tonight.