Today I perfomed several broad-band noise injections to check how large the coupling of MICH, PRCL and SRCL noises are to DARM, and to check if they are stationary.

In summary:

• MICH and PRCL couplings are stationary (spectrograms in fig. 1 and 2)
• MICH and PRCL are both contributing significantly to DARM noise below ~20 Hz (probably through the same mechanism, fig. 3 and 4, where the noise projection is shown)
• SRCL coupling shows a non stationary behavior above  ~70 Hz (fig. 5), but the SRCL noise projection is well below the DARM noise (fig. 6)

Some more details follow.

While injecting noise in an AUX channel, if the coherence with DARM is good, we can estimate the linear transfer functon TF. Then we can check if the PSD of DARM during the noise injection matches the PSD of AXU times the transfer function: the two should be equal if the coupling is dominated by a linear term. If there is strong non-linearity or strong non-stationarity, the two can be different. This is the case for SRCL (fig. 6).

The plan for the next days is to repeat this same kind of tests with ASC degrees of freedom.

As a side note, while injecting PRCL and SRCL I caused two lock losses. In both cases I'm quite confident that nothing was saturating. However, after the aborted SRCL injection, we relocked and found a mode at 41.02 Hz largely excited (SNR ~ 1000). This mode is unidentified, but seems to roughly match the roll mode of the triple suspensions.

For future reference, attached the logfile of the injections.

J. Kissel

I got charge measurements today, data files live in
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGL3/Data/
data_2016-01-19-18-26-30
data_2016-01-19-18-37-10
data_2016-01-19-18-48-53
data_2016-01-19-19-00-36
data_2016-01-19-19-12-29
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMY/SAGL3/Data/
data_2016-01-19-18-26-45
data_2016-01-19-18-38-30
data_2016-01-19-18-50-13
data_2016-01-19-19-02-04
data_2016-01-19-19-13-57


Data will be processed later.

Attached are 7 day pitch, yaw, and sum trends for all active H1 optical levers.

I reset the 35W FE watchdog at 18:17 UTC (10:17 PST).

I also noticed the crystal chiller water reservoir was very low; I added 200 mL of water.

Related: 25010

I wanted to see how well the LSC feedforward performs from 10 to 600 Hz.

I injected noise into MICH (and then SRCL) twice: once with the FF on and once with the FF off.

In both cases, the FF improves the coupling in the bucket, but makes it worse elsewhere. We already knew this was true around a few hertz (22586), but it seems to also be true above 500 Hz or so.

The intrinsic couplings (no FF) seem to have an uptick approaching 1000 Hz.

Locked in NLN and observing bit set to preventive maintenance upon arrival. Tuesday maintenance has begun per Richard's entry.

IFO has been locked steadily last 12 hours.80 MPC.
0745 took IFO out of Observing for start of Maintenance.  People were ready to go and LLO was down.
0745 S and K electric to EX air handler room to look at heater wiring.
0750 Chris S. will be resuming beam tube sealing on X2.

I have schedule 3 more hardware injections (2 burst and 1 cbc), to begin at 20:30 PT (04:30 UTC), with the last one at 21:10 PT (05:10 UTC). Here is the updated schedule:

1137213017 2 1.0 burst_GPS_76.264_

1137214217 2 1.0 burst_GPS_76.266_

1137215417 1 1.0 coherentbns1_1135135335_

Quick Summary: The IFO is ready for the hardware injection. I've informed Adam and he will schedule the injection to start in 20 mins. Jenne and Sheila are waiting to do some work after the injection is done. Wind is picking up a bit (~10 mph). Useism cruising at 90th percentile. Nominal seismic activity in the earthquake band. Robert finished his PEM injection earlier today. Gabriela and Sheila got to do some commissioning work. All the locklosses since 20:00 UTC were caused by excitations.

In order to reduce the number of saturating pixels, I changed the exposure time of the following digital cameras:

• OMC TRANS (cam20), 4861.1 => 100
• ITMX (cam21), 100000 => 6944
• ETMX (cam25), 100000 => 7639
• ITMY (cam23), 100000 => 3472
• ETMY (cam27), 100000 => 6944

In particular, the OMC camera may be confusing when one checks whether OMC is on a correct resonance or not. Since I am currently not trying to get some useful quantities out of them, one can feel free to change them to other values.

Evan, Kiwamu,

As some of us have already noticed, there is a broadband noise with a 1/f^{0.5} shape in frequency from 60 to 200 Hz. This noise is unidentified.

Do not believe any statements in this report until futher analaysis. Something is fishy with the claibration of the cross-spectrum.

We are planing to check how stable this noise level is over the course of the entire O1.

The below shows an example spectrum of DARM.

Blue curves are twenty spectra of DARM (aka C01 frame, converted into displacement), each of which is made by the Pwelch with Hanning, detrended, 50% overwrap for a 12 minutes time series. The data starts at a GPS time of 1134604817. Green curves are the square-root of twenty cross-power-spectra of DCPD A and B which are reconstructed from the sum and null streams of the DCPDs. The DARM suppression effect was removed from the sum signal. The cross-spectra are then calibrated to the displacement using the latest O1 DARM model of the calibration group. No time varying correction (i.e. kappas) is applied. Red line is a 1/f^{0.5} line to show how steep the slope of the green curves is. I also attach the fig file.

Seismic activity in the earthquake band has come back to its nominal after a 6.0M earthquake in Fiji. Useism stil high but trending downward (still at 90th percentile though). Wind <10mph. CDS overview thinks there's still an excitation to the LSC but Gabriele said he had already stopped the excitation.

model restarts logged for Sun 17/Jan/2016 No restarts reported.

The message:

The second harmoinc upconversion we see in DARM is much larger than can be explained by a quadratic term in the actuator response on any one of the suspension stages we use to drive DARM. Also, the coil balancing for ETMY L2 is a little bit off. 

Details:

We have seen that driving DARM at frequencies from 5-10 Hz creates a second harmonic in DARM (alog 21240).  One of the tests Evan and I have been thinking about doing for a while is driving each suspension stage in pringle to look for a second harmonic in DARM.  The idea is that if we drive pringle, as long as the coil balancing is good there should be no longitudnal DARM motion at the drive frequency, although there would be longitudnal motion at the second harmonic frequency. This allows us to look for a quadratic actuator reposnse without having to worry about any quadratic effect in the sensors.

The second harmoinc upconversion we see in DARM is much larger than anything we can see by driving pringle on EMTY L1, L2, L3 or ETMX L2.  (all the stages we use for DARM, plus ETMX L2 as an extra).

I repeated an injection similar to what we did in alog 21240, injecting a 500 counts at 6Hz into ETMY ISCINF. This resulted in a similar level of second harmonic.  Then, using the lockin I excited pringle on each stage individually, creating a drive to each actuator that was significantly larger than the drive generated by the DARM excitation. 

First attachment:  ETMY L1 pringle drive. In the case where I was driving DARM you can see the excitation at 6 Hz in L1 MASTER OUT and the second harmonic at 12 Hz, when I drove pringle a factor of 5 harder on each osem, there is no second harmonic showing up.

Second attachment: Same for ETMY L2, driven a factor of 10 harder for pringle than DARM. You can see in the DARM spectrum in the upper panel that the coil balancing is a little off, so the pringle drive couples to DARM at 6 Hz a little bit.  Also it is difficult to see the darm second harmonic in the master out for L2, probably because ASC drive signals dominate.   I did a similar test for ETMX L2, and there is similarly no second harmoinc in DARM.

Third attachment:  Same for EMTY ESD.  We would expect to have some quadratic term to the ESD actuation since we don't use the linearization for ETMY, and you can see that even in the green trace where pringle is driven.  However, this quadratic term is clearly much smaller than the one that causes the second harmonic when we drive DARM.

There is a script to help set these measurements up, in /sheila.dwyer/Noise/UPCONVERSION/PRINGLE_SETUP.py

It seems like the next thing to check is the sensors, for which we would like to transition DARM control to a true differential arm.

So after the long overnight-lock, H1 dropped out of lock mid-shift (Robert was at EY, but we were running ragged for the last few hours with fairly high low-frequency seismic motion).  

• Took over 3.5hrs to get back to Observing
• There were many types of issues, IMC would drop out, ALS locking was hit or miss, and then DRMI locking wasn't trivial~~And we watched our noisy envirnoment.
  • A word about this seismic motion.  We see useism slowly trend up and down without raising an eyebrow.  The odd occurrence last night/today is that the EQ band (0.03-0.1Hz) also slowly increased over the last 18hrs up to 0.3um/s.  (the normal behavior here is that it would stay flat, and only have "quick" increases due to EQs, wind gusts, or people walking around seismometers)
•  We tried switching to all 90mHz Blends, back to our "standard 45mHz", and currently have ALL 45mHz blends engaged.
• After 1-2hrs of locking, H1 finally made it!  Took it to Observing (after accepting with the 45mHz filters for the ETMs).

Note:

There were a few new tricks which Sheila taught me when we were working on locking H1 in these noisy conditions:

1)  When the ALSy was having trouble locking, we did a Clear History (yellow button on the ALS screen).  This then gave us a very misaligned Y-arm (but this was taken care of fairly easily by adjusting only yaw on only ETMy).

2) While waiting for PRMI, POP 18 & 90 looked pretty bad.  So, while in this state, the PRM was misaligned and then we adjusted the BS by eye while looking at ASAIR video.

These were two new tricks which I was not aware of.

J. Kissel, R. Savage, LHO Operators

Tallying up the progress so far on the schedule of PCALX excitations at high frequency (see plan in LHO aLOG 24802):
                                                        Achieved     Planned 
Frequency    Amplitude   Start Time      Stop Time      Duration     Duration    Success?
(Hz)         (ct)        (mm-dd UTC)     (mm-dd UTC)    (hh:mm)      (hh:mm)     (Yes / No, reason if no)
------------------------------------------------------------------------------------------------------------------------------
1001.3       35k         01-09 22:45     01-10 00:05    01:20         01:00      Yes

1501.3       35k         01-09 21:12     01-09 22:42    01:30         01:00      Yes

2001.3       35k         01-09 18:38     01-09 21:03    02:25         02:00      Yes

2501.3       40k         01-09 12:13     01-09 18:31    06:18         02:00      Yes
 
3001.3       35k         01-10 00:09     01-10 04:38    04:29         04:00      Yes    

3501.3       35k         01-10 04:41     01-10 12:07    05:26         06:00      Good Enough!

4001.3       40k         01-09 04:11     01-09 12:04    07:55         08:00      Good Enough!

4501.3       40k         01-10 17:38     01-11 06:02    12:24         12:00      Yes

5001.3       40k         01-11 06:18     on-going          (as long as we can get)


Thanks to all of the operators who have been dilligently caring for these lines while we sleep!

For the record, while these PCALX calibration lines are on, the majority (if not all) of the range is consumed, so we cannot perform PCALX hardware injections.