9/4 DAY Shift:  15:00-23:00UTC (08:00-16:00PDT), all times posted in UTC

Summary:  Able to get a few hours of Observation time during the shift.  Also had a few hours of PEM Injections by Robert.  Coordinated a bit with LLO with regards to when to drop out of Observation as well.  All of this is pointing us toward a goal of having long double-coincidence duty cycles for the next week so we can get an idea of the state of our machines going into O1.

Robert plans to continue with injections into the evening so he can have a lighter day tomorrow.

Handed off a nice H1 (~70Mpc) to Nutsinee with quiet seismic and slight winds.

Poll of Control Room Work:  PCal/OMC model work, Calibration Analysis, PEM Injection analysis, Ops Script work.

Support:  Had Commissioners around, but not needed since H1 was locked the whole time (since 16UTC / 10pm PST)

Day's Activities

• Apollo due to come in this morning to deliver a compressor to Staging
• 15:33 Airflows being lowered this morning from 15,000cfm to the standard 11,000cfm (Bubba)
• 17:48 Pepsi truck arrived
• 19:20 svn up ran on CAL_INJ_CONTROL.adl to correct bug on screen (Duncan)
• 20:10 PEM INJECTIONS begin (Switched to "Commissioning"!)
• 21:19 -21:20:  Went to Observation briefly to see if hitting the "Reset WD Only" button for HEPI (to clear HEPI saturations) drops us out of Observation:  IT DOES NOT.
• 21:59:  Back to Observation (PEM Lunch Break)

ECR: https://dcc.ligo.org/LIGO-E1500373

userapps/cal/common/models/PCAL_MASTER.mdl

1. Changed it such that IN1 instead of OUT duotone channels are recorded on frame so there's no way timing information is compromised by user error.
2. FPGA duotone IN1 (not output) is in science frames at 16k. There are two end stations, so two new 16k channel in science frame per IFO.

userapps/omc/h1/models/omc.mdl

1. FPGA duotone (ADC0 CH31) is sent to OMC common block.

userapps/omc/common/models/omc.mdl

1. FPGA duotone signal is sent to cdsFilt in the omc block, and IN1 is recorded as OMC-FPGA_DTONE_IN1_DQ in science frame at 16k. The name was chosen so that the pcal and omc signals are consistent.

h1calex, h1caley and h1omc were all successfully built but not installed. These will be installed on next Tuesday.

The seized up compressor on the supplemental chiller unit for the staging building, commonly described as the AAON Unit has been replaced, charged, and is now running at 100%. 

Chris S. Joe D. Both 70%

This week the guys have cleaned the original caulking and installed metal strips on 200 meters of tube enclosure on the top side. 

They have also cleaned the caulking on an additional 60 meters of enclosure.

I had stepped out the control room for ~15min, and when I came back the first thing I noticed was a YELLOW "OK" on the GWIstat screen.  I asked around the Control Room to see if anyone knew why we were out of Science Mode (granted I should have announced my exit), but no one seemed to notice the drop from OBSERVATION. 

I took us back to Observation Mode immediately since there was no reason given for having us out.  I looked in the Verbal Alarm terminal, and did not see a note of the Intent Bit being changed.  (So, I've talked to TJ about getting this in the Verbal Alarm script.  And to also have time stamps attached to the Intention Bit alarms so we'll know when these come up.

Keita admitted he was the culprit; he opened a DTT session [which has an excitation], and then started it.  (We tested this, while in Observation mode, and we were able to open this DTT session, which had excitation selected, and this did not drop us out.  Robert & I thought that just opening a session would drop us out.  He mentioned that maybe this is the case with AWG.  We should test whether it can drop us out.).  So this is when we were out:

16:19-16:29UTC Out of OBSERVATION

Addendum:

Prior to PEM Injections, Robert and I wanted to check if AWG does in fact have a different effect with regards to staying in Observation Mode with Excitation channels.  Robert opened an AWG session (no drop), but once he merely selected an excitation in AWG, we were dropped out of Observation Mode.  This is even WITHOUT hitting the "Set/Run" button!

When you do this, the DIAG_EXC guardian Node gets an orange box and has the message:  EXC:  [system] excitation!

We were dropped out of Observation at:  20:10UTC due to this excitation being selected (and NOT run) (this was different from what DTT did).

The noise below 30 Hz looks a bit non stationary, see the zoom in of the attached spectrogram. 

The behavior of the noise reminds me very much of scattered light, but I'm not 100% positive right now.

For some reason Evan is reluctant to make a new post about it: LHO alog 21210, comment 5 (H1NB_2015-08-27_123000.pdf)

Due to a crazy big offset of -0.5 in Y_TR_B_PIT (for SOFT modes sensing), Y IR QPDB is almost always railing a bit in 24W operation, and Y IR QPDA is not too far.

Next time IFO drops out of lock, somebody needs to lower the whitening gain by 3dB and set a new dark offset for each quadrant.

The landscapers will be out this weekend-Saturday and possibly Sunday for weed control in front of the OSB, Staging Building, and the LSB.

Patrick handed off an H1 which has been at Nominal Low Noise since about 5:30utc (10:30pmPST) with a range hovering around 70Mpc.  There was a noticeable step down in range (~60Mpc) at 12:04UTC for about 30-60min (Patrick notes several ETMy saturations around 12:10UTC & Ed notes there were earthquakes aroudn 12:15UTC).

Injection around 11:15UTC?

Looks like we have been in Observation Mode since 6:00UTC, but GWIstat says we've only been in this state since about 11:15UTC (this isn't Peter's Burst from last night....maybe a Transient Injection?  Or some other injection?  Is there a schedule for these things??).

Today's Outlook:  PEM Injections for good chunk of day

Will stay in Observation a little, but Robert says he said would like to start PEM Injections within an hour or so (~16:45UTC?), and will be PEM Injecting for a good chunk of the day so he does not have to do much on Saturday.  Have just talked with Lisa at LLO and they will be interested when we go out of Observation, so they could also go out and do some much-need commissioning.

Seismically, we look fairly quiet with microseism noticeably trending down by 0.1um/s over the last 24hrs.  Winds are also quiet.

ER8 Day 18, no restarts reported.

Per request by Robert Schofield, I am lowering the air flows in the LVEA to allow him to preform his injections.

These will be going down from ~15000 CFM to ~11000 CFM. Since the weather is cooling down, I will leave these flows at this rate until something or someone convinces me otherwise.

12:45 UTC Christina here
12:51 UTC Karen here

More SUS ETMY saturation alarms. Most if not all were coincident with glitches in the spectrum. List of all from verbal alarms script:
SUS E_T_M_Y saturating (Fri Sep 4 8:13:12 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 8:28:3 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 8:28:5 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 10:40:16 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 10:51:18 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 11:15:5 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 12:10:24 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 12:10:26 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 12:10:28 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 12:10:30 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 12:47:13 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 12:47:26 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 12:47:29 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 12:48:39 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 13:24:44 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 13:24:46 UTC)
SUS E_T_M_Y saturating (Fri Sep 4 14:44:33 UTC)

Nice quiet shift otherwise. H1 remains in observing mode around 70 Mpc.
Handing off to Corey. 

A scheduled burst hardware injection was done early this morning, at GPS 1125390500 = Sep 04 2015 01:28:03 PDT, that was extremely loud.  It was detected by Coherent WaveBurst (see https://gracedb.ligo.org//events/view/G181472) and also produced several MBTA triggers that were inserted into GraceDB, with (inferred) coalescence end times up to 37 seconds later.  I have removed all future burst injections from the tinj schedule file so that no more will be done until we sort this out and make sure that future injections will have reasonable amplitudes.

Dan, Daniel, Evan

Summary

The addition of a 9.1 MHz bandpass on the OCXO output has removed the broadband excess noise between DCPD sum and null. The dashed lines in the figure show the sum and the null as they were three days ago (2015-08-31 7:00:00 Z), while the solid lines show the sum and the null after the filter was inserted.

Details and review

Since at least June (probably longer), we've had a broadband excess noise between the sum and null DCPD streams. Stefan et al. identified this as 45.5 MHz oscillator noise a few weeks ago (20182).

In parallel, we switched the 9 MHz generation from an IFR to the OCXO (19648), and we installed Daniel's RFAM driver / active suppression circuit (20392), but the excess noise remained (20403). For a while we suspected that this was 45.5 MHz phase noise (and hence not supressed by the RFAM stabilization), but the shape and magnitude of the oscillator phase noise coupling (20783) were not enough to explain the observed noise in the DCPDs, under the assumption that the OCXO phase noise is flat at high frequencies (20582). For that matter, the shape and magnitude of the oscillator amplitude noise coupling were also not enough to explain the observed noise in the DCPDs, assuming a linear coupling from the RFAM (as sensed by the EOM driver's OOL detector) (20559).

Daniel et al. looked at the 45.5 MHz spectrum directly out of the harmonic generator in CER, and found that most of the noise is actually offset from the 45.5 MHz carrier by 1 MHz or so (20930), which is above the bandwidth of the RFAM suppression circuit. This suggested that the noise we were seeing in the DCPDs could be downconvered from several megahertz into the audio band.

Yesterday there was a flurry of work by Keita, Fil, Rich, et al. to find the source of this excess noise on the 45.5 MHz (21094 et seq.). Eventually we found circumstantial evidence that this excess noise was caused by baseband noise out of the 9.1 MHz OCXO.

Tonight we installed a 9.1 MHz bandpass filter on the OCXO output. This has removed the huge 1 MHz sidebands on the 45.5 MHz signal, and it also seems to have greatly lowered the coherence between DCPD A and DCPD B above a few hundred hertz.

Loose ends

The chain from OCXO to filter to distribution amplifier currently involves some BNC, since we could not find the right combination of threaded connectors to connect the filter to the amplifier. This should be rectified.

Also, it appears that our sum is lower than our null in a few places (400 Hz in particular), which deserves some investigation.

The attached pdf contains current Stage-1 and Stage-2 NB model performance of ITMY chamber for X,Y,Z and RZ dof. 

Fig 1- ST1 ITMY X
Low frequency near microseism model performance is limited by the ground blend filter (HEPI L4C+IPS)
1-5Hz frequency band is limited by GND-STS passing through the sensor correction path
5Hz and above (upto 10Hz say) is limited by Stage-2 back reaction
Below microseism model does not match with actual performance.       (May be because of some tilt coupling??  But it looks like actual measurement is limited by the sensor noises (T240/CPS) via isolation filter. - Not sure about it)

Fig 2- ST2 ITMY X
Instead of T240 BLND OUT,  I have used T240 BLND IN as the input (stage-1 displacement) to the ST-2 model.
Though the model and measured GS13 are in agreement above blend frequency (250mHz), the shape between 1-3Hz are not same. The model output looks more like the input signal T240 BLND IN.  May be a better input noise model will work better. 
Since the stage-2 model performance above ~1Hz is highly dependent on stage-1 displacement, we can san say that the Stage-2 back reaction on stage-1 can have effect on the final performance of the model. 
Fig 3 - ST1 ITMY Y

Most of the features and model performance are same as X dof.

Fig 4 - ST2 ITMY Y

Though this one is same as ST2 ITMY X only thing I have noticed here is the actual IFO ST1 performance is better than ST2  between ~ 300-500 mHz. 

Fig 5- ST1 ITMY Z

ST-1 model performance matches the actual measurement at almost all the frequency range of interest.  
The conclusions derived for ground model and Stage-2 back reaction hold here too.   

Fig 6- ST2 ITMY Z

Unlike X and Y dof, the model performance between 60 to 250 mHz is quite good (I am still trying to figure out why this sort of discrepancy exists between these dofs ???)
At the same time the mismatch between model and actual performance above 5Hz is noticeable. Model is over estimating the actual performance here (though the model has already included stage-2 back reaction in Stage-1)
Fig 7- ST1 ITMY RZ

Apart from the limitations of the model due to ground noise at low frequencies, the performance of this stage is mostly limited by CPS sensor noise via BLEND+ISO  path.

Fig 8- ST1 ITMY RZ
   
Please DO NOT go through this figure. Still need to sort out the problems.

   
Same sort of features can be seen in almost all the BSC chambers except BS where the stage-2 controllers are not in use. 

This entry is meant to survey the sensing noises of the OMC DCPDs before the EOM driver swap. However, other than the 45 MHz RFAM coupling, we have no reason to expect the couplings to change dramatically after the swap.

The DCPD sum and null data (and ISS intensity noise data) were collected from an undisturbed lock stretch on 2015-07-31.

Noise terms as follows:

• Shot noise
  • For 20.0 mA dc on the DCPD sum, we expect a shot noise of 8.0×10⁻⁸ mA/Hz^1/2.
• Dark noise
  • Dan and I measured this a few months ago. In full lock we use one stage of whitening, which amounts to a dark noise of 1.5×10⁻⁸ mA/Hz^1/2 or so above 100 Hz. We have at times experimented with two stages of whitening, but it requires some vigilance regarding the violin modes.
• Intensity noise
  • Coupling was measured à la Kiwamu by leaving the outer loop off and driving the inner-loop excitation point. For the noise estimation, I used the outer loop out-of-loop sensor. Since Sudarshan et al. previously found that this is artificially high, this estimation is an upper limit (though probably no more than a factor of 3, given Sudarshan's plot).
• Frequency noise [CARM sensing noise only]
  • Previously (i.e., when we locked CARM using the in-air REFL sensor), I estimated the coupling by looking at the TF in-vac REFL to DARM, and for the frequency noise estimation I used the noise of in-vac REFL as an upper limit for the frequency noise. Since we now lock with in-vac REFL, which has more light on it than in-air REFL does, I do not expect that the noise of in-air REFL is a particularly useful upper limit for the frequency noise.
  • Therefore, I have tried to instead estimate the sensing noise in CARM (from in-vac REFL, the summing-node board, the common-mode board, and PDH shot noise) in V/Hz^1/2 and propagate it (using the Izumi/Sigg expression) into a frequency noise in Hz/Hz^1/2. For the CARM optical TF I use 12.7 W/Hz at dc, with a pole at 0.48 Hz.
  • Then I have injected noise into CARM and looked at the TF from the residual of the excitation into DARM. This is the coupling TF needed to propagate the estimated sensing noise to DARM, assuming the CARM gain is high (this isn't quite true at high frequencies; the ugf is 17 kHz or so, and the gain does not exceed 20 dB until 3 kHz).
  • Since this includes sensing noise only (and not, for example, FSS noise), I have labeled it as a lower limit. In fact, the coherence between REFL 9Q and the DCPD sum is about 0.04 around 7 kHz, perhaps suggesting a frequency noise contribution of 2×10⁻⁸ mA/Hz^1/2 or so. More investigation required.
• Oscillator phase noise [not included here]
  • Stefan and I measured the coupling of the 9 MHz RF source into DARM, and using the expected performance of the OCXO estimated the noise in DARM should be 2.8×10⁻¹⁰ mA/Hz^1/2 at 1 kHz. This is quite low (and not shown on the plot).
  • This number should be replaced with Alexa's and Daniel's measurements of the phase noise. An even more satisfying number could be made by trying to measure the 9 MHz and 45 MHz phase noises in situ, closer to the EOM (e.g., at the output of the distribution system on the ISC rack).
• Oscillator amplitude noise [45 MHz only]
  • In this case we know that the 45 MHz RFAM is the dominant contributor (other than shot noise) to the DARM noise above a few hundred hertz. Here I use Stefan's estimate of the RFAM-induced photocurrent (1.8×10⁻⁸ mA/Hz^1/2), which (as he notes) is not enough to explain the excess between sum and null.
  • However, based on tonight's measurements using the new EOM driver readback, it seems that 45 MHz RFAM is enough to explain the excess. Perhaps Stefan's measurement is an underestimate, since it was done at the output of the distribution system and did not include the final rf amplifier before the EOM.
  • As for 9 MHz RFAM, Stefan and I made an estimate of the coupling from the 9 MHz source into DARM. Based on the specified performance of the OCXO, the expected noise in DARM is quite small. However, it would be better to look somewhere further downstream, as Stefan did (although I think he said the measurement was not that clean). This noise is not estimated in the plot.

The downward slope in the null at high frequencies is almost certainly some imperfect inversion of the AA filter, the uncompensated premap poles, or the downsampling filter.