Kiwamu, Nutsinee

We did a quick test with the HWS yesterday hoping it might fix the issue of HWSY sled reflected off the CP (alog29905). We first moved the ITMX and ITMY CP by a few hundred counts to confirm that only HWSY has sled reflection from CP. Then we swapped the X(790nm) sled and Y(840nm) sled then repeat the process. HWSY still had most of its reflection from the CP. The conclusion is, using different wavelength didn't matter.

We removed the HWS plates and stopped the code. This configuration still remained.

During this test we noticed that HWSX looks clipped. Not sure when did this started happening but Kiwamu said the data from HWSX he's been using make sense. No major misalignment to the SR3, ITMX, and BS in the past few days. A small touch to the top and bottom periscope fixed this clipping.

Josh, Andy

Summary: The ASC AS_C INMONs were overflowing on 9/23 but not 9/24. We're not sure if this has any negative consequences. 

During O1 we were asked to report any overflows that happened in analysis ready time. The summary page for overflows for 9/23 had a lot of entries but nearly all of them were at the lock loss. Of the handfull of things that overflowed for longer periods we looked at the ASC AS_C INMONs.

These overflowed the entire lock on 9/23 (like in fig 1) but were not overflowing in O1 (fig 2) and were not overflowing in the most recent lock on 9/24.
The histograms of the values for segs 2 and 4 are compressed around -32768 (though these are not integer counts and that value is exceeded) (fig 3).
We're not sure if this translates into problems for AS_C, but there is somewhat elevated noise in those channels now compared to O1 (fig 4,5) and those channels are used for ASC SRC2 which in turn has ~5-10Hz coherence with SRCL (fig 6).
But AS_C channels have not much coherence with DARM (fig 7).  

We thought it was worth reporting even if there isn't an obviously bad consequence. 

Title:  09/23/2016, Evening Shift 23:00 – 07:00 (16:00 - 00:00) All times in UTC (PT)
State of H1: IFO is locked at DC_READOUT. Environmental conditions are not that favorable. Winds are a Fresh Breeze with gusts to Near Gale (19-24 base, gusts to mid-30s). Seismic activity is elevated but still below 0.5um/s, microseism is also elevated and getting worse due to a mag 6.3 EQ in the Philippines. Set ISI-Config set to EARTH_QUAKE_V2.            
Commissioning: The commissioning team is working feverishly ahead of projected arrival of the EQ. 
Outgoing Operator: TJ
 
Activity Log: All Times in UTC (PT)

23:00 (16:00) Start of shift
23:10 (16:10) Kyle – Back from Mid-Y
23:41 (16:41) Lockloss – Mag 6.3 EQ near the Philippines 
23:45 (16:45) Nutsinee – LVEA to adjust HWSX alignment
23:49 (16:49) Keita – Going into the LVEA
00:02 (17:02) Keita – Out of the LVEA
00:04 (17:04) Kiwamu – Tour in the LVEA
00:11 (17:11) Nutsinee – Out of the LVEA
00:30 (17:30) Kiwamu – Out of the LVEA
04:08 (21:08) Relocked at NOMINAL_LOW_NOISE with 51.0W & 53.2Mpc	
04:30 (21:30) Set Intent Bit to Observation
04:52 (21:52) Lockloss – Mag 5.8 EQ near New Zealand
05:25 (22:25) ETMX – RMS WD tripped - Reset
05:26 (22:26) HAM6 – SUS & ISI WD tripped – Reset
06:25 (23:25) Locked at NOMINAL_LOW_NOISE	
06:26 (23:06) Intent Bit Set to Observing
06:30 (23:30) Ending Shift 


Title: 09/23/2006, Evening Shift 23:00 – 07:00 (16:00 – 00:00) All times in UTC (PT)
Support:  Kiwamu, Sheila,         
Incoming Operator: N/A

Shift Detail Summary: It was a struggle to relock the IFO after the Philippines earthquake. With much assistance and perseverance, were able to relock and eventually take the IFO to NOMINAL_LOW_NOISE. The environmental conditions are good. Wind is no more than a Light Breeze (max 7mph), Microseism is centered around 0.08um/s. However, seismic started to ring up due to a Mag5.2 EQ near New Zealand, which eventually broke lock. Was able to switch the ISI to Eaeth_Quake_V3 before Lockloss, but not soon enough to prevent the Lockloss. 
  
The New Zealand EQ was followed by back to back Mag4.9 & Mag4.7 earthquakes near the Reykjanes Ridge. Seismic recovered in about an hour. Much trouble relocking, and Roll Modes still a bit elevated. Finally, able to get to NOMINAL_LOW_NOISE with Intent Bit set to Observing. Will take a small success and call it a night before another earthquake comes along to break the lock.   	   	 

Not much progress has been made toward understanding the ITM charge mystery of aLOG 29699 and earlier. I tried to get quad-specific charge information before the earthquake hit tonight, but I found the data had insufficient SNR at my excitation amplitude.

To measure effective bias voltage of an ITM, read /ligo/home/chris.whittle/Documents/ITM_CHARGE_README.txt, set appropriate excitation amplitude/frequency and run /ligo/svncommon/SusSVN/sus/trunk/QUAD/Common/Scripts/ESD_TM_charge.py as (for example)

python ESD_TM_charge.py -l -m -o ITMX

(further instructions in the readme).

To perform a swept sine measurement, set the bias voltage to your desired value, then open the DTT template at /ligo/home/chris.whittle/Documents/charge/itm_charge_sweep_sine. You will have to set an envelope for the excitation frequencies. Previously, /ligo/home/chris.whittle/Documents/charge/analyse_sweep.py was used to calibrate and re-plot this data (requires transfer functions and coherences from charge measurement and pcal measurement).

ISS has true in-loop signal called H1:PSL-ISS_SECONDLOOP_RIN_ERR1 that is picked off of the error point of the second loop board, and we also have pseudo in-loop and out-of-loop sensor called RIN_INNER and RIN_OUTER that are digital sum of indivisual PD output.

In the morning we noticed that pseudo in-loop and out-of-loop sensors have huge low frequency noise (first attachment, brown).

Three problems were identified:

1. The scaling operation to make RIN somehow involved dividing by 1st loop sensor DC though this is unnecessary. This 1st loop sensor is green on the same plot and perfectly  agreed with brown.
2. The digital SUM of individual diodes seemed to be limited by the single precision math (red, blue). This is because individual PD output has large DC.
3. Somehow it seemed as if the pseudo in-loop signal was larger than out-of-loop and it seemed as if in- and out-of-loop was swapped.

The first problem will be solved by model change, but for now we disabled the scaling.

The second problem was solved by adding HPF in the RIN_INNER and RIN_OUTER.

After these, huge noise was gone, and now the RIN_INNER became smaller than RIN_OUTER, but the discrepancy between the RIN_INNER and the true in-loop signal didn't make sense (second attachment).

We went to the floor and disconnected the PD5-8 cable from the front panel of the chassis, and confirmed that all PD 5-8 signals went away, and got confident that INNER- and OUTER- are NOT swapped anywhere.

However, when I connected the cable back, PD5 signal had a huge offset, and the DC channel and the whitened channel were opposite in sign, which doesn't make sense. It seems like something happened on the transimpedance board.

We turned the power of the chassis off, disconnected the PD5-8 cable, and powered it on again, and the PD5 DC channel has a huge offset.

We did NOT put PD5-8 cable on PD1-4 connector as we feared to break PD1-4 channels.

The chassis will be pulled for investigation on Tuesday.

TITLE: 09/23 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Lock Aquisition
INCOMING OPERATOR: Jeff
SHIFT SUMMARY: Some morning work on the AS_C QPD whitening, then after that was done locking started but was severely slowed by some ASC issues when engaging DRMI ASC. Kiwamu narrowed it down to either SRC1 or SRC2. When he engaged these separately, it seemed to work, but when the guardian did it simultaneously, it would crash within ~30s.
LOG:

• 15:57 - Hugh, Jim to  EX to check on Beckhoff code
• 16:06 - Richard to CER to work on AS_C QPD Whitening
• 16:19 - Chandra, Gerardo to CP4
• 16:23 - Hugh, Jim back
• 21:08 - Nutsinee to LVEA to get Hartmann Plate and cable swap
• 22:08 - Nutsinee out.
   

3pm local

12:15 to overfill CP3 with 1/2 turn open on LLCV bypass (exhaust bypass left open)

*while I was out there, I closed bypass exhaust valve on CP4 from this morning's activity

Chart shows changes of the IM alignment over

• O1 start to end (Aug 2015 to Jan 2016)
• O1 end to Current (Jan 2016 to Sept 2016)
• O1 start to Current (Aug 2015 to Sept 2016)

IM3 yaw from O1 start to Current has changed by -111urad, highlighted in blue.

This morning, I have measured the in-loop and out-of-loop spectra of the second loop ISS when it was closed at 50 W with the recently-installed-boosts using an SR785. This was without the full interferometer but the IMC. Here is the results.

The purple, blue and red curves are all the in-loop spectra (i.e. SUM14) but with different frequency resolutions. The yellow, green and cyan curves are the ones for the out-of-loop sensor (i.e. SUM58). The interpretation and implication of this plot will be posted by Keita, Daniel and Ben later. The data, plotting script and figures are also attached as a zip file.

This is a follow-up study for 29524, 29556,

Synopsys- With the current CO2 and ring heater settings, the readout gain for laser frequency with REFL45I does not flip the sign any more during and after the power up.

Some details- Here is a screenshot showing the sensing gain for laser frequency at REFL_A_9I and REFL_A_45I from the last night. The sensing gain were monitored by the mod/demod technique at 900 Hz which is the same as what Stefan did in the past (29524, 29556).

• (blue) REFL_A_9I using DEMOD_2 [arbitrary unit]
• (green) REFL_A_45I using DEMOD_3 [arbitrary unit]
• (brown) power recycling gain [W/W]
• (cyan) IMC input power [W]

Very similarly to the past observations, REFL_9I maintains a steady gain throughout the measurement. REFL_45I was also stable. Its sensing gain changed by a factor of two from the beginning of the 50 W operation to the end of the measurement (for about 35 minutes). As opposed to the previous observations, REFL_45I did not experience a large deviation of more than factor of two or sign flip. This is consistent with our experience in the sense that the interferometric loops can hold the interferometer locked without significant changes during and after the power-up.

Some notes on the thermal settings that we used in this measurement:

• CO2X 500 mW --> 240 mW (as we power up)
• CO2Y 1000 mW --> 0 (as we power up)
• RH [ITMX, ITMY] = [0.5 W, 2.5 W]
• RH [ETMX, ETMY] = [1.5 W, 0 W]

Always learning something new:  10% open on LLCV at CP4 is too low to maintain a cool LN2 transfer line. 20% is a good value. 

CP4 was overfilled yesterday and left in PI mode overnight with a lower limit set at 10%. Pump level was reading ~88% this morning so I raised set point from 90% to 92% and the signals from pump level fluctuated sporadically from 78-98% and the exhaust pressure rose to levels around 4-5 psi in PI mode with LLCV close to 100% at times. Conclusion is we're cooling the transfer line with increased LN2 flow so I've left the exhaust bypass valve open temporarily, until transfer line is cool and PI behaves as usual.

I removed the flow meter and flex line from CP4 exhaust. Configuration is same as other cryopumps.

I'm not sure how the gains on the IM alignment sliders were set, but currently pitch is at 0.023urad/slider_count, and yaw is at 0.085urad/slider count.

So the motion per 1 slider count for pitch is much different than for yaw, and I think it would be good to correct this.

I've attached a chart showing the current and target alignment slider gains, and the current and target alignment slider urad/slider_count.

I set the target urad/slider_count at 0.01, so 100 counts on the slider is equal to 1urad change in optic position, and I'm not sure how that compares to other optics, but is reasonable for the IMs.

For the past day or so the diode chiller temperature has been fluctuating by a couple of degrees with a period
of ~90 seconds.  The fluctuations are noticeable in the temperature of the diode box heatsinks, and in the
injection locking voltage for the oscillator.  Maybe not so noticeable in the output power of the oscillator,
and not in the diode box output power.

    The diode TECs are compensating for the temperature fluctuations.  Since the TECs solely adjust the temperature
of the laser diodes, the temperature fluctuations are clearly caused by the diode chiller.

SEI - Jim W needs to head down to EX to check on some PLC code.

SUS - Good.

CDS - HW: Whitening filter that was switching, see Sheila's alog (alog29925).

    SW: fw went unstable yesterday, investigation ongoing (alog29911).

PSL - Up and running.

Vac - Chandra will still run tests on CP4 when possible.

Reminder: ER10 will not start next week, pushed back to the end of October.

Following on from yesterday's diffracted power versus applied AOM RF power, the coefficients for the
parabola calculating the percent diffracted power has been changed.

old: 97.675 x**2 - 63.548 x + 11.458
new: 134.794 x**2 - 106.473 x + 20.9997

The calculated fit is only good for AOM drive values greater than 0.300V (which is almost always
the case, historically).

The transfer function of the first loop ISS was measured before and after the coefficient change.
The UGF was not affected.

    Attached are dumps of the MEDM screens taken before and after the coefficient change.  The before
and after transfer functions around the UGF are attached to show that no change in the UGF was observed.

3pm local

CP4 = cryopump #4 at mid Y

John, Chandra

First, this morning we installed type K thermocouples along the exterior of the nitrogen exhaust pipe outside - one ~1 ft the exit of the building, one mid way down, one at the end of the SS exhaust line, and the last inserted inside the plastic flex tube (also the flow meter measures temperature).

We repeated yesterday's CP4 experiment by doubling LLCV (66% open) and allowing CP to overfill beyond 100% until LN2 came out the exhaust. I was physically at the exhaust line during the violent transition taking temp. measurements along exhaust. LN2 sputtered into plastic flex tube, so I quickly opened bypass exhaust valve and closed manual LN2 fill line on main Dewar (temporarily). It didn't help that during this chaos there were reverberations from an airplane or big truck in the distance that sounded like the entire arm coming up to air.

Temp measurements along the exhaust line (degC):

Time      TC1 (wall)     TC2 (mid)     TC3(end)     TC4 (flex tube)     TC5 (flow meter)
14:07     -27.4          5.8           21.9         22.8                -
14:43     -25.2          11.1          25.9         26.1                28.xx
14:55     -27.5          10.1          26.2         26.2                -
15:01*    -57.5          -49.3         -57.6        -193.8              -0.5
15:30     -23.1          13.7          15.6         16.3                19.7

*LN2 out the exhaust

Flow meter seems to be functioning still

John and I are considering installing a TC inside the end of the exhaust pipe at CP3 to use both this signal and the exhaust pressure to develop an automated fill every 2-3 days (no flow meter).

Jeff K, Sheila, Chris Whittle

Having recently taken measurements for the CARM and IMC loops with the newly installed 200 kHz pole (aLOG 29735), we have begun an investigation into whether we can boost the gain in CARM to help mitigate frequency noise in DARM without compromising loop stability. We used the following form of the CARM open loop gain:

G_CARM ~= g_CARM * H * ( g_IMC * G_IMC / (1 - g_IMC * G_IMC) )

where g_IMC and g_CARM are tweaked, and G_CARM and G_IMC were measured (see above). H is a combination of the electro-optical CARM plant of the IFO and the electro-optical IMC plant, and is calculated from the above measurements. We are ignoring the slow path here as we are far above the 30 Hz crossover. See aLOG 22188 for more details.

Note that the closed loop gain of the IMC was extrapolated back to 1 kHz from 10 kHz (assuming a unity CLG below 10 kHz).

The OLG of the IMC loop shows that we can't get away with an IMC gain much grater than 2 dB without hurting our phase margin too much. Similarly, the loop suppression of the IMC loop significant gain peaking above 2 dB.

With g_IMC = 2 dB, our CARM phase margin suffers above g_CARM = 2 dB. This gives us a a factor of 2.08 dB suppression in our CARM loop suppression. We therefore propose increasing CARM and IMC loop gains to g_CARM = 2 dB and g_IMC = 2 dB. Although this introduces some additional UGFs, all are stable, and the worst of which has a phase margin of 31.6​​^∘​.

The script for producing these plots can be found at:

I took a quick look at six hours of 30-minute SFTs automatically
created by FScans this morning (thanks for setting the intent bit!),
to see if recent line mitigation attempts have reduced the amplitude
of the 1-Hz and other combs at low frequencies. Unfortunately, 
the low-frequency noise floor is too elevated to say much yet
about that mitigation success, but in the band 28-32 Hz, where
last night's noise is lower, there do seem to be fewer and lower-level
lines, including reduced amplitudes for the 1-Hz comb with a ~0.25-Hz offset.

Please note that the 56.84-Hz comb reported in the ER9 data
(present but weaker in O1 data)  remains quite strong.
There are other strong lines present, too, but I gather noise-hunting
is just getting started. The 56.84-Hz comb suggests a DAQ problem
somewhere, as noted before.

The attached plots show different bands of O1 data (narrow black curves)
superposed on last night's data (broad red swath). In each case, an 
inverse-noise weighting is used, to suppress periods of elevated noise.

Figure 1 - 10-2000 Hz
Figure 2 - 10-28 Hz
Figure 3 - 28-32 Hz
Figure 4 - 32-50 Hz
Figure 5 - 50-100 Hz
Figure 6 - 100-200 Hz
Figure 7 - 200-1000 Hz
Figure 8 - 1000-2000 Hz