Attached is a rough trend of the amount of water we have added to the TCSY chiller over the last week in order to keep it "topped off".  There is ~kinda a downward trend, which may indicate we are finally getting to the point where the system is "full".  Recall, Wed Sept 28th the system ran dry due to a leak at the chiller.  At that time the chiller was refilled with ~5L of water.  We have since added another 5L of water (~300mL at a time over the last week).  The reservoir holds 7.2L and the piping probably takes a few more L so, maybe we are still clearing out air leaks in the whole stsyem...

We'll just slowly filling and watching for another few days and replot.

Evan, Daniel

17:12:30 UTC Oct 7 2016:

• RF modulation off for 9 and 45 MHz
• 45 dB whitening gain compensated by a filter gain of 0.0056
• 1 stage of whitening, compensated
• V/ct filter engaged, referred to TNC ouptut of 2-chn demod board
• Dark

17:16:30 UTC Oct 7 2016:

• same input configuration
• 29 mA of photocurrent

17:18:30 UTC Oct 7 2016:

• turn DC centering of REFL WFS on

17:24:30 UTC Oct 7 2016:

• turn DC centering off again
• 14.8 mA of photocurrent

17:32:00 UTC Oct 7 2016:

• 9 MHz modulation on
• 14.8 mA of photocurrent
• DC values: 9I = 3.7 mV; 9Q = 9.5mV

17:34:30 UTC Oct 7 2016:

• 9 MHz modulation on
• 29 mA of photocurrent
• DC values: 9I = +7.2 mV; 9Q = +18.1mV

18:06:30 UTC Oct 7 2016:

• 9 MHz and 45 MHz modulation on
• 29 mA of photocurrent
• DC values: 45I = –14.3 mV; 45Q = +62 mV

SEI: All OK – Working on ESs sensor correction
SUS: No Report
CDS Ele: All OK
CDS Swt: All OK – Fixed problem with bad commissioning frame effecting NDS
PSL: All OK – PSL has been running since the Diode controller swap
TCS: No Report
VAC: All OK – Kyle planning for the 5 day RGA bake out at End-X

There was only a short, not very good lock, after the DBB signal started to be acquired. I used ten minutes of data from GPS 1159862777 to compute the coherence between DARM (CAL-DELTAL) and the DBB QPD signals.

The first plot shows that the most coherent signal is Q1Y.

The second plot shows the transfer function from Q1Y (in arbitrary units, not sure about the calibration) to CAL-DELTAL (properly calibrated in meters, including the de-whitening filter). The shape is quite smooth, and it looks like a monothonic increase like f for most of the range. The low frequency noise of the IFO was quite bad, so I could only measure coherence above 100 Hz. Hopefully this will be improved in future locks.

However, I could fit the measured transfer function between Q1Y and CAL-DELTAL with a 3rd order model. The fit is shown in the third plot: the result is reasonably good.

I then converted the model into a IRR filter and computed the time-domain subtraction of the Q1Y signal from DARM. The result is quite good, most of the bump has disappeared, see the 4th plot for a comparison of the spectra and the 5th plot for the residual (basically null) coherence of the subtracted DARM with DBB signals.

Of course, we'll have to check in future locks how much this coupling changes over time and how hard it is to compensate for this change.

Trying to check where the laser power went to.  From the attached plots, the drop in laser power
is not easily explained by a power drop in the laser diodes.  So my suspicion is that there's a
small resonator alignment change.  Perhaps not all that surprising given the temperature change
of the laser due to being off for a few days.

Just a quick report. Broadband noise in 200-1000 Hz was also visible at a mid-high input power of 27 W.

I did not insert the cutoff filters in the hard ASC loops. ISS 2nd loop was fully engaged with a gain of 19 dB and the boost on. TCS was held at the lock acquisition settings, i.e. [CO2X CO2Y] = [500 mW 1000 mW]. The period when the interferometer was low-ish noise is in 8:15 - 8:25 UTC which was followed by lockloss due to me failing to handle PI mode 27.

Terra, Travis, Kiwamu,

Here are some unexpected issues that we addressed tonight.

• AS36 -> SRM
  • As mentioned earlier (30295), we had stability issue with the AS36 -> SRM loop in the DRMI state with the arms held off resonance.
  • One immediate human error we found was an integrator not engaged in DC3 pitch loop.
  • However, engaging the integrator in DC3P did not improve the behavir of the loop running away.
  • In the end, we changed the input matrix. AS36BI: +2 --> +1.
  • This solved the issue. Not sure why we had to change the input matrix.
• AS WFS DC and fast shutter
  • At one point, we ran into a situation where ISC_LOCK did not proceed because the shutter guardian reported a failure in a shutter test.
  • This was found to be a failure report from the dark test in which the light level on AS WFSs A and B were checked with the shutter closed.
  • In the end, we found that the AS WFS DC signals now had a slower low pass filter (a 2nd order butterworth at 1 Hz in FM1), which was too slow to give a low enough light level. This used to be a 2nd order butterworth at 5 Hz yesterday.
  • We re-installed the 5 Hz BLP in FM2 and edited the FAST_SHUTTER and ISC_LOCK guardians so that it uses FM2 when in test.
  • It worked once.
• AS90 jumped multiple times
  • We witnessed a funny behavior of AS90 a few times tonight.
  • It suddenly changes its level by a few % or so when DRMI was in lock with the arms helf off resonance.
  • Times to look at are around 2:13:19 UTC and 3:30:00 UTC.
  • DRMI did not lose lock.

TITLE: 10/07 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Lock Aquisition
INCOMING OPERATOR: None
SHIFT SUMMARY:  Started shift with an initial alignment.  After IA, spent the entire shift working with Jenne and Kiwamu diagnosing issues with ASC loops and fast shutter.  Only made it past DRMI a few times.
LOG:

5:30 Filled TCSY chiller

6:00 Shift end due to early start for 3IFO meeting
 

Kiwamu, Matt E, Terra

We broke our overnight lock this morning from Mode2 (ITMX 15520.7 Hz) ringing up; usually this is easily damped back down with a slight phase change but there was no operator in the chair at the time. This mode has been especially prone to ring up with very minor (a few degrees) phase drifts as the frequency drifts over ~3 hours lock across a static bandpass. 

I measured this mode's open loop transfer function last night (with the same settings it later rang up with). Width of loop is 24 mHz; cursors at UGFs shown on transfer function plots. Measured Q of mode is ~20 M, giving a half-width of 0.776 so the gain on resonance of our loop is about 31. Phase differential across this fairly wide frequency range is ~160 deg, so we're close to instability. 

To this end, I've halved the gain of the damping drive. I also shifted the bandpass filter: previously the resonant frequency range was sitting slightly off center picking up ~30 deg and now it shifts around within ~2 deg phase window (for a five hour lock at least). We had trouble locking tonight and are now working at low power, so I'll have to remeasure another time. 

Joe B, Darkhan T,

From the past day's lock stretches it seems that now the DARM time-dependent parameters (kappas) calculated in the CAL-CS model are mostly within expected ranges. The optical gain seems 10% lower compared to what the DARM model suggests.

Related alogs (kappas from September): 30219, 29992.

Cal. line coherence averaging:

Coherence calculations in the CAL-CS front-end model outputs overestimated coherences for the calibration lines between Sept. 20 and now. The issue will be fixed by replacing the averaging C code, BUFFER_AND_AVERAGE.c with a previous version (modification to the script proposed in LHO alog 29744 will be reverted).

The first figure shows the results of 2.5 cycles of crystal chiller total flow variation (24.2 l/m vs. 22.2 l/m) in DARM and in the 1QX signal of the DBB quad diodes. The diode signal shows a detectable increase with flow from about 60 to about 6000 Hz, with the biggest increase in the 1000 Hz region. DARM increased from about 200 to 2000 Hz, with the biggest increase around 450 Hz.

The second plot shows other DBB diode signals.  The peaks do not change as much as the rest of the jitter spectrum (see 1000 Hz). The lower percentage changes at some of the peaks are more consistent with the changes in table accelerometer signals. The water signal is apparently a less dominant driver of the peaks than of the smooth regions, and the source of the peaks may therefore be easier to access and damp should need be. 

Robert, Jason

Jonathan, Jim, Dan, Dave

Jim W reported data errors from 06:14PDT this morning in the full frame. We found that the commissioning frame file for this time is correct on the LDAS QFS file system, but corrupt when NFS exported by the h1ldasgw2 NFS server machine to the nds machines. This is a relatively new solaris server installed this summer to take read-only exports away from h1ldasgw0 when h1fw0 was unstable.

I've opened an FRS for this #6370

Investigation is continuing, including a full characterization of the problem.

Dave, Nutsinee

There are still some issues (several white channels on the medm screen, unclear where the files are being written) but so far the new code runs on Ubuntu 14 at both end stations without complains.

(Corey, Jason on phone)

Last night, Nutsinee came in early for her OWL shift & just before midnight the PSL tripped.  We opted to leave it tripped for the night to wait for Jason to walk us through recovery procedure.  Atleast for now, we always want to run through this procedure with one of our PSL people (Jason or Peter K).  Here are my rough notes:

• Control Room PSL card (in key box) just passed its 7-year expiration date on Fri
• Remote login (with Jason)
• Went through a few steps in procedure and during a 5-min wait, I went out to Fill the low Crystal Chiller.
  • Both Chillers were on (but not chilling).  The Crystal Chiller (on top) had a "Flow sensor 1" error (but Jason says this is a generic error).
  • The cap blew off and was on the floor
  • Topped off with 375mL Laboratory Water
• Continued with procedure with Jason
• Once laser back, worked on restoring PSL systems via medm.
• Had to RESET the Noise Eater (toggle switch to OFF [for ~5sec], then ON).  This switch is at the "NPRO box" which is the Innolight box on the right most elec cabinet outside of the PSL Room; has the sticker:  "AdvLIGO observatory No3" on it.)
• Then brought everything back (actually the PMC, FSS & IMC came back on their own.  Had minor actions to bring back the ISS).
• Last task is to wait 30min to hit the LRA button (can't remember what Jason said this stood for) & then ENABLE the Oscillator & Frontend WatchDogs.
• Closed out Remote Login interface.
• Time on phone with Jason:  ~60min

Now on to "Aligning" on Observatory Mode!

PSL Status NOTE:

• Have a Warning Red light under the Laser's HPO (not sure what this means).
• ISS Autolock is RED (not sure what this means either since the Autolock is ON & GREEN on the ISS screen).

BS horizontal wedge doesn't have any couterpart Y path. Any horizontal beam shift on the BS will cause MICH path difference because of this wedge.

(CPY has a horizontal wedge but it's a mirror image of CPX about BS HR surface. ITMY has a vertical wedge but again it's a mirror image of ITMX.)

This effect doesn't look small, and a rough calculation shows that the HPO jitter peaks from DBB (but not broad humps seen in DBB) are consistent with what we see in DARM.

----

In the attached cartoon, when the beam on the BS is shifted in Y direction by y (blue line), the optical single-trip distance from the beam spot on the BS to ITMX gets shorter than to ITMY by:

EQN1: MICH = n*yW*sqrt(2)/cos(theta) - yW*(1+tan(theta)) ~ 0.7896yW = 1.0E-3*y

where W=1.3E-3 rad is the wedge, n=1.4496 is the refractive index and theta=29.2deg=0.5096rad is the angle of refraction.

DARM will only see about (1-rI)/(1+rI) of MICH where rI is the amplitude reflectivity of the ITMs, which is sqrt(0.986):

EQN2: DARM=MICH*(1-rI)/(1+rI) = 3.5E-3*MICH ~ 3.5E-6 * y.

Because of this, DARM should have a flat coupling to YAW displacement on BS.

Instead of the displacement y, we'll use the displacement A which is just the displacement normalized by the beam radius on the BS (53.4mm):

EQN3: DARM=3.5E-6*53.4[mm]*A = 1.9E-7 [m] * A.

----

Now, let B be a normalized misalignment parameter out of HPO (i.e. HPO jitter), e.g. B=disp/waistRadius+ i* angle/divAngle. Note that abs(B) is conserved unless 01/00 mode ratio is altered.

PMC gives us 1.6% HOM01 suppression in amplitude (T0900616).

For IMC there's some difference for PIT and YAW due to additional sign flip on top of Gouy shift per round trip, but PIT suppression is about 0.5% and YAW is 0.4% in amplitude assuming that the common round trip Gouy shift is 102 deg.

For PRC, assuming carrier recycling gain of 30, PRM reflectivity of 97% and the round trip Gouy shift of 32.5 deg, HOM01 suppression is 5.7% in amplitude.

PMC, IMC and PRC combined, HOM01 suppression is 3.7e-6 for YAW, 4.6e-6 for PIT.

Though A cannot be known without knowing the Gouy shift from HPO to BS, since |B| is conserved except through cavities, we can set the upper bound on |B| using the HOM suppression through PMC, IMC and PRC as

EQN4: |A| < 3.7e-6 * |B|

therefore upper bound on DARM

EQN5: DARM < 7E-13 [m] * |B|.

DBB measurements of B are available in alog, e.g. alog 29754 (direct link to the HPO jitter plot is here).

If you look at 1kHz peak which does not appear in DBB RIN measurement, the peak height is somewhere between 5E-6 to 1E-5, and using EQN5 and these numbers,

EQN6: DARM < 3.5 to 7E-18 [m/sqrtHz] at 1kHz peak.

In DARM spectrum, 1kHz peak is visible at or somewhat above 1E-19 [m/sqrtHz], so it seems consistent with EQN5.

----

Caveats:

IF the broad noise in DBB jitter measurement is actually jitter,  assuming the same jitter coupling as the above, you should see the huge broad thing in DARM, which we do not.

This coupling only applies to YAW. As for PIT, there could be similar coupling mechanism if ITM wedges don't cancel with each other, but the imbalance is only 0.001 degree.

MICH is not the only thing that is modulated by this, SRCL and PRCL are simultaneously modulated. Full simulation might be useful.