Scott L. Ed P. Rodney H.

7/30/15
The crew relocated lights, fans and cords to begin cleaning the next section starting at HSW-2-043. 51 meters of tube cleaned ending l2 meters east of HSW-2-041.
I repaired several of the extension cords and a cord on the vacuum used for cleaning the support tubes. 

7/31/15
Ed took today off. 
The support vehicles and all related equipment were relocated after lunch and a total of 61 meters of tube cleaned today ending 13.7 meters east of HSW-2-038.

The past ~200 meters of tube have been especially dirty with feces and urine. We have been giving these areas extra attention.

1239.5 meters of Y-Arm cleaned to date.

Stefan, Jim, Andres, Filiberto, Dave

WP5392

New h1calex and h1caley models were installed today, these read out ADC3-CHAN30 as the IRIGB signal. These signals were added to the commissioning frame and the frame broadcaster. The DAQ was restarted at 11:55 PDT to install this change.

Something happened at lock loss and the IFO did not reach the defined DOWN state.

Symptoms:

• SUS: ITMX, ITMY, ETMY - driven and rung up, watchdogs tripped, I had to adjust the RMS limit on ETMY from 8000 to 10000 to reset watchdog
• SEI: ITMY ISI tripped - Jim rest
• IO: MC WFS left pushing optics to a bad place and needed to be cleared by hand
• PSL: ISS and FSS in oscillation - outer loop on while IMC was unlock, throwing inner loop into oscillation
• GRD: ISC_LOCK - red for a while, cleared after INIT

Dave, Jaime, Sheila, operators, and others are investigating.

I ran BruCo on the quiet data period reported here. The report can be found at the following link:

https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1122369690/

I'll look into the table and provide a summary later today.

Between 11:10 and 11:25 I adjusted the frequency offset and the phase offset in the timing diagnostic system's cesium clock in MSR so that the 1PPS time difference between it and our GPS backed timing distribution system equals 0±100ns and the long-term drift rate is near zero.

Last time I adjusted the timing offset (3 weeks ago), I subtracted 68e-15 from the factory-set frequency offset of 1078e-15; this was apparently the wrong direction, as evidenced by a very visible doubling in the cesium clock's drift rate in the weeks since that adjustment. Since the last measurement of drift rate was calculated from a month's worth of data and was ostensibly accurate, I went ahead and changed the frequency offset to (1078+68)e-15. The manufacturers instructions are vague on the correct adjustment direction and the tech support reps aren't very knowledgable, so I'm going to write up a short technical paper on Cs-III calibration with specific instructions for how to go about this.

I zeroed the phase using a 1PPS signal from the MSR master. The GPS timing jitter is O(10ns), which is well within the 100ns resolution of the CsIII phase syncing utility. I used a short (3') BNC cable to minimize delay.

I also went ahead and installed the most recent Monitor3 software on the Lenovo X61 Thinkpad in MSR and put the Cs-III instruction manual on that computer's desktop, so it should be easy for someone else to make finer adjustments to the frequency offset once we have another month or two worth of 1PPS drift data. 

at 10:37 PDT the IOP model on h1oaf0 received a timing error, all models stopped running at this time(h1pemcs, h1oaf, h1tcscs, h1odcmaster and h1calcs). The calculated IFO range went to a high value and the DARM FOM display went noisy. Only one external model receives IPC from the h1oaf0 computer, h1omc has a dolphin channel from the calcs, these channels went into 100% error.

There was PEM work in the CER around this time, this could have been the cause of the glitch. All the models were restarted and all is running correctly now. The intent bit was not set during this time.

BRS software crashed on the 25th, so today I went to EX to restrart the code. I kept the damper commented out, so the damper is currently OFF. I will turn it back on when it seems like it will be calm down at EX for a bit (vac team is down there right now).

Within a min afer a lockloss, the ISI ETMY ST1/2 WDs tripped. The medm said that it was ST1 T240 and the plots showed a slow drift to the WD trip level (plot attached). HEPI moved 170 um after lockloss before tidal began to bleed down. A further investigation is ongoing by the SEI team.

CDS: EE shop work to prep for Ring Heater installation
PSL: Wants to tweak PR3 OpLev at first available opportunity
FAC: Continued beam tube cleaning Y-Arm   
VAC: Moving pump cart to End-X for weekend long RGA bake out

Evan, Matt, Lisa

We took ~25 min of undisturbed data starting at Jul 31 2015 09:21:13 UTC , after the MICH FF improvement (and  all the changes described earlier  implemented), with the interferometer locked in low noise ~ 65 Mpc (according to SensMon).

We saw a big glitch during this period (~9:28), a huge one right before (~9:18, right after the mich tuning was done), and another one at the end of the undisturbed period. 

We went back to commissioning mode as Evan is starting some noise injections for his noise budget.

Commissioning Team

For the meeting tomorrow, here is a list with the things that we changed this week, and they are now part of the baseline locking sequence:


1) more aggressive cut-off in MICH, to reduce coherence with DARM above 50 Hz (log 20020 );

2) more aggressive cut-offs in the  ASC_AS_A / AS_AS_B --> OM1 / OM2 centering loops (from 100 Hz to 20 Hz) to remove some coherence with those signals reported by Bruco;

3) more aggressive cut-offs in the OMC SUS alignment loops ( log 20087 ) to remove unwanted OMC length motion which was observed to cause fringe wrapping by Josh et al (log 20079 );

4) heroic modification of the DHARD loops (both PITCH and YAW) during the locking sequence, aimed to make the transition to REFL/TR and carm offset reduction more stable by increasing the phase margin of this loop, which was kind of poor and was seen to cause several lock losses in the past (log 20084 ); these loops have now high ugfs (~ 5 Hz) and >30 degrees phase margin.  Note that the ASC work is not done yet: tomorrow we will add cut off filters, and attack CHARD. Also, we haven't yet succeeded in turning off the ITMs optical levers, which are still on;

5) modification of the ISS loop to improve phase/gain margin (log 20088  and log 20088 );

6) IMC WFS --> PSL PZT loop to reduce ~300 Hz peaks in DARM ( log 20051 );

7) found and fixed a sneaky ramp time problem which was causing the switch from ESD ETMX --> ETMY to fail repeatedly (log 20076 ), Jenne got a BIG PLUS for this one;

8) added an offset to PR3 during the CARM offset reduction to counteract the wire heating ( log 20055 )

9) the Guardian usercode has been modified to speed up the locking sequence ( log 20055 ), and improve IMC_LOCK;

The interferometer has been happily locked in low noise at ~ 65 Mpc for nearly 2 hours with all the above changes implemented, and the Guardian has been updated. 

10) (Later edit) Evan just optimized the MICH feed forward, and he reduced the MICH coupling between 30 and 50 Hz; the sensitivity is now better in that region. 

Other things in our to-do-list for tomorrow:

1) More alignment work (cut-offs and CHARD)

2) Test the whole sequence again to check robustness

3) Track down the TMSX weirdness (log 20078)

4) Noise investigations and injections for noise budget

Sudarshan, Matt

The new ISS filter was seen to oscillate at ~1MHz with no input signal.  This was fixed by adding 50pF cap into the feedback of the output opamp.  This cap, in combination with the 10k resistor, puts a pole at 300kHz, which is fine for this loop.  The second loop is currently closed (with the IFO at high power) and appears to be working properly.

Evan, Matt, Josh S. (in spirit)

The OMC ASC  loops now have 0.5Hz cut-off to remove unwanted OMC length motion (see plot).  This change is intended to reduce the OMC SUS velocity so that we don't get fringes in DARM.

The filters are in OMC-ASC_{POS, ANG}_{X, Y} loops (see screenshot), and do not appear to cause stability problems (because the UGFs are below 100mHz) with the MASTER_GAIN up to 0.2, though some gain peaking is observed at this gain.  The normal operating gain is 0.1.

Matt, Evan

Why do the TMSX RT and SD OSEMs have such huge spikes at 1821 Hz and harmonics? These spikes are about 4000 ct pp in the time series. In comparison, the other OSEMs on TMSX are 100 ct pp or less (F1 and LF shown for comparison).

Also attached are the spectra and time series of the corresponding IOP channels.