We had a long steady lock stretch this morning so I'm looking at the coherences between the ReflA signals and HAM1 HEPI motion.  Jeff & Sheila report coherences at 5-7hz and the microseism.

Attached are HAM1 IPS and L4C coherence plots with REFL_A_RF9_I. I wasn't going to mess with the IPS but I chose that channel and did not notice until I had produced the plot so I include it.  Both sensors see plenty of coherence at both microseisms with narrower bands around 5 to 10hz.  There is also L4C coherence between 2 & 400mhz in X & Z.  Almost all DOFs show some coherence with both Pitch & Yaw.  I'm having trouble wrapping my head around what coherence with the IPS means.  The platform is moving relative to the ground to make IPS signal.  We should be well locked to the ground with the position only isolation loops at the microseism but does that mean we are too locked or not locked hard enough to the ground.  Inertial sensors are so nice.

I see now Jeff included REFL B.  I did not include these signals. 

Sudarshan, Darkhan

Fixed 2 of the Epics values used for calculation of DARM time-varying parameters, in particular values that supposed to be equal to a complex quantity

EP2 = (C_0(f_pcal) / (1 + G_0(f_pcal))) * (C_0(f_ctrl) / (1 + G_0(f_ctrl)))^{-1}                          (1)

Initially the constants to be used for calculation of DARM time-varying parameters using a method described in T1500377 were taken from ER7 model and written into Epics records with a Matlab script (see LHO alog 20452 and 20361).

Due to mistyping a variable name in the Matlab script, Epics records H1:CAL-CS_TDEP_REF_CLGRATIO_CTRL_REAL and H1:CAL-CS_TDEP_REF_CLGRATIO_CTRL_IMAG that must represent real and imaginary parts of EP2 were set to have the same values as real and imaginary parts of EP1 (see Table 2 of T1500377-v7).

On Thursday, Aug. 27, 2015, around 10:00am PDT we replaced these Epics record values to represent the correct values calculated from H1 DARM model for ER7:

H1:CAL-CS_TDEP_REF_CLGRATIO_CTRL_REAL = 0.9814270
H1:CAL-CS_TDEP_REF_CLGRATIO_CTRL_IMAG = 0.0227508

SDF_OVERVIEW was updated accordingly, and updated Matlab script was committed to calibration SVN:

CalSVN/aligocalibration/trunk/Projects/PhotonCalibrator/drafts_tests/20150808_values_for_cal_EPICS/ER7model_valuesForEpics.m

Jeff, Evan

There is now a new DMT viewer template for viewing the BLRMS of the corner and end-station STSs. It is userapps/isc/h1/scripts/Seismic_FOM_STS.xml.

This is meant to replace the Guralp DMT viewer template.

Right now it only displays the lowest two BLRMS (0.03 to 0.1 Hz and 0.1 to 0.3 Hz).

[As an aside, the frequency bands implied by the channel names in DMT viewer don't seem to match up with the front-end channels. For example, the front-end EX-X channels are named as follows:

H1:ISI-GND_STS_ETMX_X_BLRMS_100M_300M
H1:ISI-GND_STS_ETMX_X_BLRMS_10_30
H1:ISI-GND_STS_ETMX_X_BLRMS_1_3
H1:ISI-GND_STS_ETMX_X_BLRMS_300M_1
H1:ISI-GND_STS_ETMX_X_BLRMS_30_100
H1:ISI-GND_STS_ETMX_X_BLRMS_30M_100M
H1:ISI-GND_STS_ETMX_X_BLRMS_3_10

while the DMT channels are named as follows:

H1:ISI-GND_STS_ETMX_X_DQ_0p03-0p1Hz_48h
H1:ISI-GND_STS_ETMX_X_DQ_0p1-0p2Hz_48h
H1:ISI-GND_STS_ETMX_X_DQ_0p2-0p35Hz_48h
H1:ISI-GND_STS_ETMX_X_DQ_0p35-1Hz_48h
H1:ISI-GND_STS_ETMX_X_DQ_1-3Hz_48h

Are these BLRMS distinct from what's being computed in the frontend?]

(All time in UTC)

15:28 Kiwamu asked the intent bit to be set to comissioning. Calibration works begin.

15:30 Fil to both end stations EER (end station electronics room).

15:31 IFO lock broke. ETMX switched to high voltage

15:52 Locked at NOMINAL_LOW_NOISE. Kiwamu driving ETMX.

16:09 Fil back. Going to CER.

16:12 Fil done

16:51 EX Dust alarm went off. I checked EX dust monitor but not sure what happened to its medm screen.

17:00 Rich Abbot to LVEA. Field RF measurement.

17:13 Daniel to joined Rich.

17:40 Small re-locking issue. I didn't aware of the new method of locking PRMI so I didn't . The SRM offset was high and eventually ISI tripped. Jeff Kissel took care of the ISI.

17:51 Lockloss at SWITCH_TO_QPD see alog 20988

18:05 Locked again at NOMINAL_LOW_NOISE

18:11 Rich back for now

18:15 Rich back out

18:42 Richard to MidY

19:00 Richard back

19:07 Greg updating DMT code. This requires DMT computer restart but shouldn't affect anything in the control room.

19:15 Rich out

19:20 Nutsinee begins testing ITMX L2 DAMP MODE9 and 10 violin mode damping filters

20:00 Violin mode filtes testing stopped

20:23 Richard's intern to the roof to checck on camera

20:51 Rich back to the CER

21:00 Calibration crews took down the ifo.

23:00 Handling the ifo to Travis.

While I was out on vacation, Chris and Joe cut 3 of the 25# rolls of aluminum into 10' lengths and completed installation of those to the Mid station on the upper section of the enclosure. Additionally they have cleaned and installed strips on 240 meters of enclosure north of the Mid station to date.   

Today I replaced one of the condenser fan motors on the staging building chiller. As I was removing the motor and support/guard, the last of the spot welds broke. Had this happened during operation the fan would likely have fallen into the chiller causing a considerable amount of damage.

I took the support to the weld shop, cleaned and re-welded it.

While I had the unit disassembled, I also cleaned the coils which I would estimate were 40% blocked with debris.

 

WP 5466

Jonathan, Jim

A script has been added to gather up medm screens and put them in a tar file for exporting.  This is to support offsite viewing of medm screens for the detector.

The script runs as the controls user on script0 at 1:00 AM local time each day.  The frequency of this may be reduced to once per week when we enter O1.

Attached are ASD and Coherence betwix the three corner station STS2s taken at 3am local Wednesday Thursday and Friday.  These three days look very similar.  I installed STS2-A aka HAM2 on Tuesday.  Recap:

STS2-C (HAM5) has been in place for long time.  STS2-B (ITMY) is the unit returned from Stanford replacing PEM STS2 which we were using to replace our original STS2-B which is still at Quanterra for repairs.  STS2-A returned from Quanterra after a couple months in their vault where they say there was no problem.  The A unit spent time in the BeirGarten near the ITMy unit undergoing cable and chassis swaps, see 18354 for recap but nothing was consistent.

To me, STS2-A still looks like this unit has a problem.  When I look at plots from back in May, 18354, it looks even worse now.  There was better coherence in Z and X with the other units and Y was equally poor.

RobertS--do you have an opinion?

Travis S, Darkhan

Yesterday, Aug 27, 2015, we took Pcal end-station calibration measurements at both end-stations. The measurement procedure is described in T1500063 (-v5).

The following steps from the procedure have been completed at both end-stations:

• 3.1  DAC calibration
• 3.2  Setting up the current amplifier
• 3.3  Additional checks
• Appendix A.  Taking the measurements.

Rough numbers from MEDM screen logged into the record sheet (provided in appendix A of T1500063) suggest that RxPD and TxPD calibrations as well as optical efficiencies of Pcal beams at LHO EY did not change significantly compared to numbers from calibration on 2015-05-22, however we saw ~1 - 2 % drop in the optical efficiency of Pcal beams at LHO EX compared to measurement taken on 2015-05-20.

Calibration results will be reported after completing the last part of the calibration procedure, running Matlab scripts that acquire data and calculate responses of TxPD and RxPD:

• 4.1  Data acquisition and plots
• 4.2  Committing results into SVN

Record sheet papershots are attached to this alog.

Jenne, Nutsinee

There was a suspecious lockloss at SWITCH_TO_QPD at 17:50 UTC. We went through lockloss plots and found ASC-MICH was unstable right before the lockloss.

J. Kissel, D. Barker

Dave found that H1SUSETMY L3 LOCK L FM 2 (which has and remains OFF all throughout lock acquisition and lownoise) had been changed by Evan from compensating for the ESD driver's low pass filter (which is now done in the H1 SUS ETMY L3 ESDOUT $(QUADRANT) FM2/FM7 banks) to some other filter, and sadly did not name it so it shows up (appropriately) as "Unknown." I;m not sure what his intent was with this filter, but because is OFF all the time, I loaded the coefficients so that the model doesn't have a "modified filter coefficients" message which sets off all sorts of SysAdmin alarms.

I'll find out from Evan what his intent, and probably clean it up later.

the attached files show the current status of the front end code.

ER8 Day 11. No restarts reported

Itbit set at 10:48 UTC with long lock hopes.

New EXCITATION_OVERVIEW screen has been created:

$USERAPPS/sys/common/medm/EXCITATION_OVERVIEW.adl

Hopefully this can help in tracking down excitations that could be preventing the system from entering READY:

The two columns show the front-end excitation monitors (FEC, left) and the ODC monitors (ODC, right).

NOTE: ONLY ODC monitors count towards OBSERVATION READY at the moment.

The FEC monitors are there for reference, and for completeness.

The EXCITATIONS box in the OBSERVATION_OVERVIEW screen now contains a link to this screen.

J. Kissel, K. Izumi, C. Cahillane

Evan and Kiwmau wished to get a better answer than my supremely bold claim of being able to ALS DIFF VCO's pole and zero to 1% and 1 [deg] (LHO aLOG 20542). As such, they remeasured the ALS DIFF PLL OLGTF with no boosts, as had been done before, but this time with the PLL Common gain reduced to -32 dB([V/V]) instead of the nominal 26 dB([V/V]). In this way, they reduce the overall loop suppression, in hopes to alleaviate the non-linear distortion we had been plagued by before. The message -- they were right. The new OLGTF, with all other parameters the same, shows that the "nominal" z:p = 40:1.6 [Hz] pair fits the data better than my previously claimed z:p = 40:1.05 [Hz].

However, naturally, there is still confusion. The new *magntiude* residual shows what looks to be a descrepant pole-zero pair around 100 to 500 Hz, but there's no such affect in the phase. Recall that the frequency dependence in the model is simple -- a pole a DC for the phase-frequency descriminator, the z:p pair for the VCO, a time delay, and a single 450 kHz pole. Nothing around 100 - 500 Hz. What do we suspect? More non-linearity. Great. 

More to think on. We'll measure the PLL controller in the -32dB gain setting tomorrow to make sure it's what we hope -- non-linearity at the negative-edge of the gain setting for this box, that we can just measure and divide out.

Kyle, Gerardo 

Today we coupled the ion pump to Y2-8 -> The operation was slow and meticulous but we feel confident that no new net forces are realized by the beam tube nozzle -> We also pumped out and leak tested -> Still to do is the pulling of the HV cable and bake out -> In the meantime we will likely move on to X2-8 and repeat the exercise.  

(Note that Mike Z., Ken Mason and others provided the components used)

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.