J. Kissel, N. Kijbunchoo, K. Izumi

After deciding that we've damped the 504.8 [Hz] violin mode enough to advance to DC readout, we got a few minutes of DC readout on ETMX, and then we noticed that wind began to pick up speed a few hours ago. We lost lock, and during recovery DRMI was taking particularly long to lock back up. From Izumisan we learned that 
- If it takes particularly long for DRMI to lock up, e.g. greater than ~15 minutes,
- If one hasn't run initial alignment for quite some time, and
- The AS port shows flashes that are not strictly LG00 modes, but LG10/01 or any higher order modes
it's likely that one needs to redo initial alignment.

We began embarking on initially alignment, and found the arms difficult to lock on green. I suggested we move the blend frequency up on the beam line directions of ETMX and ETMY, as is common practice when winds are > 20 [mph] as they are now.

Just after we increased the blend frequency, the PSL laser tripped at 16:50 PDT / 23:50 UTC. Quick (and at this point only superficial) investigations do not reveal a reason. Regrettably, the global PSL team is rather busy with LLO's laser at the moment (see LLO aLOG 17959, and subsequent entries).

Kiwamu and Nutsinee are in the PSL diode room now recovering (and have done so as I finish this log).

The usual perfect storm on the first day of an attempt to leave the IFO alone and collect data!

M. Landry, J. Kissel

We injected the same CBC waveform on fourteen occasions with a variety of gains, into the DC locked machine.  The strain waveform is a 1.4-1.4 solar mass BNS coalescence, optimally-oriented, at 45Mpc (the same waveform injected into L1 during ER6). Below we summarize these injections:

Channel = H1:CAL-INJ_TRANSIENT_EXC

Waveform: /ligo/home/jeffrey.kissel/2015-04-30/injection_strain.txt

Logfiles: /ligo/home/jeffrey.kissel/2015-04-30/*.log

Daytime seismic noise from Hanford truck traffic has decreased during the last several weeks and swing shift hauling ceased completely on 4/29.  Some new work at the 300 area could bring the daytime haul numbers back up in a month, but no resumption of swing shift activity is planned for the remainder of 2015.

Scott L. Ed P. Chris S.
4/29/15 the crew clean 61.7 meters ending 7.6 meters north of HNW-4-021. Test results posted here. Removed lights and relocated to next tube section.


Ed P. Chris S. Joe D. Cris M.
4/30/15 the crew cleaned 49.3 meters ending 10 meters north of HNW-4-024.


Ed P. Chris S.
5/1/15 - 49 meters cleaned ending at HNW-4-027.
 

Beam tube pressures are continually monitored during cleaning operations by control room operator.

Quiet day of locking for the mini-run.

J. Kissel, B. Weaver, J. Warner, C. Vorvick

We lost lock about 2 hours ago, and the cause was excessively rung up violin modes, specifically the 504.8 [Hz] ITMY FL mode (ref LHO aLOG 17610), which are damped by the MODE2 and MODE4 banks of ITMY_L2_DAMP block. I attach a screenshot of the ~hours of adventure. 

To solve the problem, there's no magic bullet unfortunately. While DARM is still locked on RF, we turn on the damping loops one at a time. The "nominal" gains of -100 and 300 for these banks are too large for the current amplitude of the lines, so we have to start with a small gain and work our way up. The attached screenshot shows the progress. I'm hoping to have them reduce enough (roughly equivalent to the current Bounce and Roll mode amplitudes) to move on to low-noise in an hour or so.

J. Kissel

Again, more analysis details later, but I attach the DARM OLG TF taken this morning.

The measurement has been committed to the CalSVN repo here:
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PreER7/H1/Measurements/DARMOLGTFs/2015-05-01_H1_DARM_OLGTF_LHOaLOG18144.xml

I have noticed that there is a mismatch between Stage-2 BSC-ISI CART2ACT basis change matrix. This is true for all the BSC-ISI chambers. The first attachment shows the designed value (https://dcc.ligo.org/DocDB/0013/T1000388/017/T1000388%20SEI%20Sensors%20Location.pdf) of CART2ACT matrix while the second and third attachments show the current matrices in ITMX (or ETMY) and ITMY (or BS/ETMX)  respectively.

I have cross checked that the ST2-CART2ACT matrix stored here- /ligo/svncommon/SeiSVN/seismic/BSC-ISI/Common/Basis_Change_BSC_ISI/aLIGO_BSC_ISI_BS_ITMY_ETMX.mat is in agreement with the technical document. 

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.