TITLE: 01/14 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    Wind: 9mph Gusts, 8mph 5min avg
    Primary useism: 0.09 μm/s
    Secondary useism: 0.37 μm/s
QUICK SUMMARY:

• Jenne is relocking, made it to NLN twice
• Robert is getting ready for shaker tests

We are planning on installing 7 large magnetic injection coils that can make large enough fields to show up broad-band in DARM. Previously we have been limited to comb injections; this was fine when the coupling was dominated by permanent magnets with simple power function coupling. But now we are dominated by coupling to cables and connectors and the coupling functions are not as simple, so we want to probe more of the spectrum with broad band injections.

We were happy with the prototype (https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=43406), so we are going ahead and planning the next locations. The figure shows the proposed locations, which include the preferred order of installation.

Robert, TVo

Notes for the morning crew:

The interferometer needed some alignment work in order to lock reliably but after a full initial alignment, we were able to get up to Engage_ASC_FOR_FULL IFO pretty easily.  Still some ALS glitches in the X-ARM but not so bad that we were losing lock before shuttering.  The stopping point for tonight seems to be the engage soft loops, when initializing them PRC2 yaw gets pushed very far off until we lose lock so maybe the dither frequency change needs to get a little more tuning before we can move on.

I have been wondering about the true input power, i.e. the input power incident on PRM, ever since the SRCL dither arm power measurement turned out so low.  

Conclusion
With an input power of 1.87 watts according to the PSL photodiode, we probably have around 1.55 watts incident on PRM, assuming an addition 21% unaccounted losses in the REFL A/B LF PD path.

Power Measurement Methods
I aligned PRM and the input optics, and misaligned the rest of the corner with 1.87 W reported from the PSL input power PD going into the IMC.

IM4 Trans
The easiest way would be to get Pinput would be via IM4 TRANS.  IM4 TRANS is calibrated into microwatts, IM4 (aka SM2) transmission is reported to be 2400 +- 200 ppm, and there's what I think is a 90:10 BS (ROM LH1) allowing 10% of the light going to IM4.  However, if we turn the crank here we end up with only 0.2 W, which is not possible.  This means that IM4 TRANS is not calibrated correctly, or the IM4 transmission path is actually around 8 times less transitive that I though.

REFL A/B LF
We believe that the REFL A/B LF PDs are correct based on the calibrated CARM shot noise.  We can use them to calibrate the correct input power.  The main issue here is if we use the REFL optical path (4 50:50 beamsplitters, 1 90:10 beamsplitter, one input faraday isolator, and one PRM) and assume no losses, we only get 1.19 W of true input power on the PRM.  This could be the case, but it's more likely that there are some unaccounted for losses on the REFL path.

PSL and IMC Transmission
If we trust the old numbers from P1500076 on the PSL and IMC transmission, we can make an estimate of the true input power.  We find that by varying the PSL and IMC transmission, we cannot reasonably recover the REFL A/B power levels we see.


PD Powers and Optic Transmissions Assumed
# Most taken from P1500076

# PD calibrated powers
PSL_INPUT = 1.87 # W
REFL_A = 7.3e-3 # W
REFL_B = 6.72e-3 # W
IM4_TRANS = 50.24e-6 # W

# PD uncertainties
dREFL_A = 0.04e-3
dREFL_B = 0.03e-3
dREFL_SUM = np.sqrt(dREFL_A**2 + dREFL_B**2)

# Transmissions
T50 = 0.5
T10 = 0.1
T_PSL = 0.953 # +- 0.013 PSL to MC1 transmission
T_IFI = 0.977 # +- 0.004 https://dcc.ligo.org/DocDB/0119/P1500076/003/Mueller16rsi-AdvIO3.pdf
T_IMC = 0.92  # +- 0.031
IMC_ModeMatching = 0.984 # 0.001
T_PSL_to_IFI = T_PSL * T_IMC * IMC_ModeMatching
T_IM4 = 2400e-6 # +- 200e-6 E070092
T_PRM = 0.031 #

# Trans Uncertainties
dT50 = 0.01
dT10 = 0.01
dT_PSL = 0.013
dT_IFI = 0.004
dT_IMC = 0.031
dIMC_ModeMatching = 0.001
dT_PSL_to_IFI = np.sqrt( T_PSL_to_IFI**2 * ((dT_PSL/T_PSL)**2 + (dT_IMC/T_IMC)**2 + (dIMC_ModeMatching/IMC_ModeMatching)**2) )
dT_IM4 = 200e-6

Dither loops

I have moved the dithers of the soft loops (PIT4, PIT5, YAW4, YAW5) to lower frequencies (6-10Hz), I've yet to move PIT3 and YAW3. 

I have tested lock reacquisition with the PIT loops at their new dither frequencies, but not yet with the YAW. In addition I've moved Dan Brown's dither monitor lines. See first attached screenshot of DARM spectrum tonight, note the high frequency noise is bad as the ISS second loop is off currently. The current oscillator frequencies are summarised in an updated table below (amplitudes are for NLN, for acquisition in PREP_ASC, the amplitudes are all 1600).

Method

I switched the LOs of these loops one-by-one, at NLN. Allowing the original loops with ~20Hz dithers to converge before turning off the inputs and tuning the loops for a lower LO frequency. I tuned the clock gains so the lines are visible over the DARM noise, made bandpasses for the signal path (previous lines are all in FM6, new lines in FM4), lowered the gains (since the DARM noise is much higher at low frequency).

I tried re-phasing the loops by adjusting the A2L gain of the test mass the dither is applied to, and checking all the signal was in the I path, however the old phases seemed just fine. 

I've left the change in frequency of YAW5 out of the guardian for now since it seems slower to converge than the old loop and I didn't want to cause problems for future commissioners, so on the next lock there'll still be a line at 21.9Hz from that one (as well as the PIT3 and YAW3 lines). 

TCS y chiller flow

We got a verbal alarm that the TCS Y chiller flow was low. Seconds screen shot is of the flow rate channel around the time of the alarm. We didn't go check for leaks or anything.

A new ALS x-arm problem

We had some problems locking the x arm in green. When the ALS_XARM guardian said the arm was locked the transmitted power was extremely noisy and the transmission camera looked like it was possibly rapidly mode hopping. We struggled with this for a while, eventually with better arm alignment we managed to lock with no problem (coincidence?).

We switched DARM actuation from ETMY L2 and L1 stages to ETMX L2 and L1.  This caused a change in the MICH FF which has remained untuned while the IFO has been unstable.  Today we were stable enough to tune MICH FF again, winning a factor of 10 lower MICH to DARM coupling and improving the low frequency DARM noise.  
The new FF is saved as Jan11b in the MICH FF FM3, and gets engaged by guardian in LOWNOISE_LENGTH_CONTROL.

Georgia and I got back up to NLN.  Georgia started moving the ASC dither lines to lower frequency, but was unable to finish due to a 1 Hz very slow ringup in our yaw loops.  I killed the lock by increasing both the CHARD P/Y digital gains by a factor of 2 in an attempt to save the lock.
Georgia has since moved the ASC dither lines back for acquisition tomorrow.

Lost lock once while trying to get back through ENGAGE_SOFT_LOOPS again.  After this lockloss I measured the dark noises of REFL A, REFL B, IMC REFL, and the IMC and Common Mode Servo Boards.  Left the SR785 plugged in to the CMB.

During the ~hour lock at NLN 30 W, I measured the CARM loop around the FSR, in a repeat of a measurement Evan took three years ago, intending to measure our CARM pole this way.  My measurement is lopsided in magnitude, where Evan's was symmetric, but both exhibit the familiar overcoupled cavity phase rotation.  Further modeling required.

Sheila, Danny 

• We wanted to investigate the 380-410 Hz peaks in DARM noted by Robert in alog 46373
• Sheila noticed that there was a strong coherence between the seismometers and the ISS in loop diodes around these same frequencies which lead us to discover the strong coherence of the ISS in loop diodes and DARM. 
• We do not notice this noise in DARM when the ISS second loop is off. 
• When the second loop is engaged  there doesn't seem to be an agreement between the out of loop sensors for this . The HAM2 ISS out of loop diodes show that there is noise suppression in this range while the HAM1 REFL diodes show that there is added noise. 
• We also note that there was a strong coherence below 30 Hz between the in loop diodes and DARM when the ISS is AC coupled. 
• Further investigations coming soon

J. Kissel

Chugging down the front-end calibration's time-dependent correction factor to-do list, I used todays locks to tune the uncertainty thresholds and then watch the performance of the gating, median-ing, and averaging (GMA) that's a replica of what the GDS pipeline had done during O2. The message: I'm not satisfied.

Check out the attached ndscope traces of the three actuator kappas during one of this evening's nominal low noise lock stretches.
On the left column, in three plots (one for each UIM, PUm, and TST kappa), I show the raw input to the GMA system, the output of the gating, the output of the median-ing, and the output of the averaging, which we hope to eventually send off to correct DELTAL_EXTERNAL and to create CFTD_DELTAL_EXTERNAL. On the right, I show the calculated uncertainty of both the respective SUS_LINE and PCAL LINE used to derive the actuator kappas.

Observations: 
- The uncertainty is low; in the 0.05 % level (we could probably reduce the amplitude of the calibration lines by a factor of ~2.)
- The raw signal wobbles around smoothly with a 10 second period, reflective of the 0.1 Hz low pass used on the output of the DEMODs.
- Given that at the time I show, the live uncertainty is passing the tuned threshold, the raw signal and the gated signal are identical. Good!
- Things start getting fishy once the signal is passed through the median function, stuff that looks like digital hair on what should otherwise be smooth portions, and there is an overall stair-step nature to it. I forget if we've studied whether (a) the O2, GDS/DCS produced, median-ed time series looked this step-like, and (b) if the application of step functions at the 0.1% level caused any high-frequency noise or glitch problems. There also appears to be a significant offset between the raw and gated value vs. the median-ed value.
- Finally, with the final, gated, median-ed, and averaged output, there's a lag between it and the input, only-gated-median-ed time series. At least the digital hair has been smoothed out...

Plenty of things to think about before I understand it enough to be happy about trying to apply these factors to DELTAL_EXTERNAL.

• Another lockloss at ENGAGE_SOFT_LOOPS.
  • Symptom: POP18 dropped when we did engage asc for full IFO, and it didn't come back up with the soft loops (even though the carrier PRG was increasing as we expect). 
  • The SOFT loops and dither loops seem to converge fine, but then an oscillation starts that we were not able to tame down.
  • 3.4 Hz was the oscillation frequency.
• A problem in the engagement of ASC loops was found and fixed. PRC1 was being engaged with some DC gain, but it should be AC coupled since the DC part will be taken care of with the dither loop.  The dither part doesn't get engaged until ENGAGE_SOFT_LOOPS, but we still don't want to be servoing to the pointing on POP_A right now, since the setpoint isn't set to handle that.  Later in the engagement script PRC1 was being AC coupled, but by then our pointing is all weird. 
  • TVo moved the AC coupling filter (FM5 in PRC1 P and Y) to PREP_ASC, so that we are certainly engaging PRC1 with AC coupling.
• ISS second loop setpoint needs to be adjusted.  When the second loop comes on (AC coupled) after DRMI locks, the diffracted power is jumping from 1.5% to 3%.  Not causing trouble immediately, but needs to be addressed sometime when we're sitting in IMC-only.
• Lost lock in PREP_ASC_FOR_FULL_IFO
  • It seems like DHARD and MICH control signals start walking off, although the error points don't seem to have changed.  So, why do DHARD and MICH feel the need to push??
• Found another wrong setting with the dither loops - YAW3 had 2 bandpasses engaged, so the PRM Yaw loop wasn't really doing anything.  But, it's been set incorrectly since Jan 4th, and we've been living.  Maybe PRM Yaw wasn't so far away in past locks, but now it needs to move farther, so the loop not engaging is causing problems??
• Something is wrong with the OMC locking.  When OMC_LOCK gets to LSC_ON, I can see the OMC trans camera oscillate a lot, then the OMC loses lock.
• Trying different ASC engagement:
  • SOFT loops: going to try engaging CSY, DSP, DSY with the DC dither loops only, and only have CSP have both dither DC and the ASC-CSOFT AC coupled portions of the loop.
  • CHARD Yaw gain increase (FM1 on, +30dB) causes things to seem to go unstable.  PRC1 Yaw sees osc. CHARD Pit and Yaw sees osc.  PRG looks more hash-y.  Leaving FM1 off for now.
  • Turned on rest of ASC, then tried CHARD Yaw again.  Rest of ASC was fine, but turning up CHARD Yaw gain made CSOFT Pit oscillate.  Leaving CHARD Yaw FM1 still off for now.
• New lock, the above ASC engagement is in the guardian (with an IF True to make it easy to put back in if needed).
  • Able to power up to 30W in this state.  CHARD Y OLG is in the low bandwidth state measured in attachment 1 for the power-up (measurement was done at 2W, while fighting a violin mode).
  • After power-up, CHARD Yaw started to ring up slowly.  We increased the CHARD Yaw gain from the 0.6 value that is set in LownoiseASC to be 3.0.  But, the +30dB FM1 is still off, so we're overall a factor of 6 lower than previous CHARD Yaw NomLowNoise gain.
  • Lost lock trying to move SRM for cavity pole improvements.
• Next lock, seems like SRC1 P more gain (SRC1 Y was given more gain a few days ago).  Also, giving CHARD_Y 5x more gain in the engage_soft state, rather than the full 30x of FM1. 
  • Factor 3x for SRC1 P now in guardian, near the place where SRC1 Y gets +20dB.
• Tried putting in offsets to the SRC1 pit and yaw loops, to see if the DARM cavity pole would react.  It's a little tricky to see what's going on in the attached ndscope figure since the IFO was still thermalizing, and there are a few times in here that Stefan was also changing DARM whitening and offsets.  But, I think that my conclusion is that the SRC1_P offset of zero is the best, and a SRC1_Y offset of negative values isn't better than zero offset.  Next lock we need to check if SRC1_Y positive offsets are helpful. 
  • The big jump in cavity pole around -1000 seconds is a "regular" glitch.  The jump around -400 sec is Stefan changing the OMC DCPD whitening condition.  Then, a few tens of seconds later he undid that change.  We lost lock on a DARM offset change. 

Prior to shift: Richard and Peter in PSL enclosure

15:56 UTC Karen to optics lab
16:02 UTC Vanessa to mid X
16:18 UTC Peter to optics lab. Karen to mid Y.
17:11 UTC Karen leaving mid Y
18:44 UTC Travis to optics lab, looking for gold mirrors for solder test
18:59 UTC Travis back
19:33 UTC Peter back
19:42 UTC Nutsinee to ISCT6

Lockloss, notification: 'PSL_FSS: PZT MON is high, may be oscillating'. Jason and Peter investigating.

20:38 UTC Nutsinee back
20:45 UTC Peter and Jason to PSL anteroom
20:52 UTC Peter and Jason back, turned off lights in PSL enclosure. Lights left on in PSL enclosure from this morning raised the temperature out of the FSS range. FSS needs to be locked manually until the temperature comes back to normal.
22:16 UTC Peter to optics lab
22:22 UTC Fire department to end X to check on RFAR
22:30 UTC Gerardo to Y2-8
Nutsinee to ISCT6
22:49 UTC Robert to end X to change measured voltage signal
23:34 UTC Peter back
23:39 UTC Gerardo back
23:55 UTC Robert back
00:08 UTC Nutsinee back

A direct comparison between the transmitted arm powers between O2 and now. The input power during O2 (8/1/2017) was 28W, whereas it is 30W now.

The errors for the transmission coefficients are listed as ±0.2 ppm.

The average power increase between the two arm cavities is 1.33. Or a factor of 1.24, if corrected for the input power. This isn't compatible with our observed increase in the power recycling gain by factor of about 1.5 (from ~30 to ~45). There is also a fairly large imbalance between the two arms, indicating there may be an inaccuracy in the optical transmission data? or?

The green power out of the SHG became lower around noon and I noticed that the temperature knob on the laser box has been locked. I left it unlocked the last time I adjusted it because the knob was too sensitive. By locking the knob the temperature was changed by .05 degree C. That was enough to put us in the multimode region. Again, 

PLEASE DO NOT TOUCH ANY KNOBS ON THE SQZ LASER CONTROLLER BOX. 

The setting has been reversed back and temperature knob was left unlocked.

I took at look at the 3.5hr lock earlier today (1231211560 - 1231224532) and do not find evidence of scattering in GDS-CALIB_STRAIN which had been present in locks prior to the DARM actuation being moved entirely to ETMX. 

I do however see whistles (the last time we saw these was back in October); hveto finds them dominating in rounds 1 and 2. Looking at individual whistles they can be seen in SRCL_IN1, SRCL_OUT, POP_A_RF45_I, POP_A_RF9_Q, REFL_A_RF45_I, REFL_A_RF9_Q and REFL_B_RF45_I/Q_YAW. We usually blame something beating with the IMC VCO for whistles, so I took all the trigger times from hveto's round 1 and 2 winners and found the IMC VCO frequency at these times. Note, not all the triggers will be whistles, but the majority will be. The attached histogram shows the IMC VCO frequencies at the time of the whistles. I also took a look at the ALS_COMM and DIFF VCOs at these times and found they were not changing at the time of the whistles.

I also took a look at the IMC VCO frequency ranges for the last few locks, just to see if it had shifted significantly. It has not. Since 10th Jan the IMC VCO frequency has been centred ~78.96MHz, but whistles only appeared in the last lock....

The figure shows that there are new peaks in DARM that appeared between the last good lock before last Tuesday, Jan 8, and the first good lock after Tuesday. These peaks are coherent with HAM2 ISI. But the motion of the ISI doesn’t appear to have increased, suggesting that the coupling increased. One possibility is increased clipping from an alignment change.

Over the holidays, this sensor went flat.  Investigation found guy line rope had parted where it turns through the ground anchor eye.  One cup was broken and the rotating shaft looks to be bent now too; I'd say it isn't likely repairable.  Photos attached.

On Tuesday, I'll replace it with my last unit available and also move it.  Additionally, I'll add chafe protection to all the guy lines.  Guys will be wire when they get to a permanent location.