Displaying reports 62541-62560 of 83002.Go to page Start 3124 3125 3126 3127 3128 3129 3130 3131 3132 End
Reports until 12:53, Saturday 29 August 2015
H1 ISC (SEI, SUS)
nutsinee.kijbunchoo@LIGO.ORG - posted 12:53, Saturday 29 August 2015 - last comment - 00:50, Wednesday 02 September 2015(21009)
Windy lockloss coherence

Kiwamu, Nutsinee

As we were trying to relock the ifo after several locklosses due to high wind (50mph), we noticed the sideband signals wiggled a lot before another lockloss at DC_READOUT (wind speed ~35-40 mph). We found a coherence between POP18, POP19, POP_A_LF, AS90 and PRM, SRM, BS which indicates that the DRMI was unstable. The BS ISI Windy blends weren't turned on. 

Images attached to this report
Comments related to this report
kiwamu.izumi@LIGO.ORG - 16:47, Saturday 29 August 2015 (21011)

One of the two lock losses seemed to be associated with PRM saturation. We heard of the saturation alarm voice pointing PRM DAC in full lock mutiple times before the lockloss in NOMINAL_LOWNOISE. I am not sure if this is the direct cause, but as shown in the attached, PRM had been experiencing ~20 sec oscillation in longitudinal which used to be a big issue in the past (alog 19850). At that point wind was around ~40 mph on average. Also, I attach spectrum of each coil on the M3 stage. It is clear that the components below 0.1 Hz are using up the DAC range when wind is high.

Images attached to this comment
evan.hall@LIGO.ORG - 13:24, Monday 31 August 2015 (21055)

Just as a check, I remade Kiwamu's plot for PRM, SRM, and MC2, with all the stages that are used for actuation.

At this point, the wind ine corner station varied between 3 and 13 m/s. The 30 mHz 100 mHz BLRMSs were about 0.02 µm/s in the CS Z (consistent with sensor noise), 250 µm/s for EX X, and 250 µm/s for EY Y.

Since this time, we have increased the offloading of PRM and SRM to M1 by a factor of 2, but we probably need an even higher crossover in order avoid saturation during these times. It may have the added benefit of allowing us to stay locked during even windier times. Additionally, MC2 does not look like it needs any work on its crossovers in order to avoid saturation.

Images attached to this comment
evan.hall@LIGO.ORG - 00:50, Wednesday 02 September 2015 (21130)

The above comment should say 0.25 µm/s for EX X and EY Y.

H1 General
thomas.shaffer@LIGO.ORG - posted 08:00, Saturday 29 August 2015 (21007)
Ops Owl Shift Summery

Stayed locked my entire shift. A fair amount of glitches though, especially toward the second half of my shift.

H1 General
travis.sadecki@LIGO.ORG - posted 00:00, Saturday 29 August 2015 (21006)
OPS Eve shift summary

Pretty smooth shift. IFO was unlocked when I arrived by request of the Calibration Team.  When they were ready for the IFO to be locked, it came up easily with the only hiccup being a switch Kiwamu forgot about.  In an attempt to speed up the procedure, I hastily went to the PRMI->DRMI step.  However, I missed a step in the procedure, which caused the SRM to saturate, and lock was lost.  It started over, and without my intervention, the IFO locked right up. 

Activity log:

23:06 Rich Abbott out of CER

0:28 started locking procedure

1:24 locked on Low Noise, ~70 MPC

6:25 Intent bit set to Undisturbed after Calibration Team leaves for the night

H1 CAL (ISC)
jeffrey.kissel@LIGO.ORG - posted 23:25, Friday 28 August 2015 - last comment - 14:53, Thursday 03 September 2015(21005)
Measurements Necessary for ETMY Actuation Scale Factors, Round 2
J. Kissel, K. Izumi

We've completed another round of the suite of actuation coefficient coefficient measurements today, very similar to what was done on Wednesday (see LHO aLOG 20940) with the same templates. There were some differences between the two days worth of measurements -- we don't expect these to have made a difference, but we've been living 1% accuracy and precision land for a week with no sleep, so we write them down anyways. They are: 
- We managed to get all of the full IFO transfer function measurements within the same lock stretch, unlike Wednesday. 
- We did Full IFO config measurements, ALS DIFF measurements, then Free-Swinging MICH (FSM) measurements, as opposed to Wednesday when we did DIFF, then Full, then FSM.
- Because we got distracted with full-frequency range DARM OLG and PCAL to DARM TFs, and there were some problems with DIFF saturating, there were about ~4 hours between when the ETMX TF was taken in full lock and when it was taken in ALS DIFF.
- On Wednesday, we ran ALS DIFF with ALS COMM OFF. Today we ran ALS DIFF with ALS COMM ON.
- We missed a MICH OLG TF for the FSM. We may try to get away with checking if the power and PD normalization levels are the same -- if they are we may just use Wednesday's data. Otherwise it means we have to scrap all of today's FSM data.

A "When will you have a number?" update: we are heavy into analyzing both of the data sets (ALS DIFF is done with the help of LHO aLOG 21001, tomorrow will be PCAL and FSM). A goal is to have a comparison between methods by Sunday.
For a sneak peak on the analysis scripts for ALS DIFF (in case LLO wants to use them), check out
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Scripts/ALSDiff
analyze_alsdiff_data_20150826.m
analyze_alsdiff_data_20150828.m


#NoSleepTilO1

The DTT files live here:
(2) /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/FullIFOActuatorTFs/2015-08-28/
     2015-08-28_H1SUSETMY_PCALYtoDARM_FullLock.xml

(5) /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/ALSDIFF/2015-08-28/
     2015-08-28_ALSDiff_ETMX_L3_HVHN.xml

(6) /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/FreeSwingMich/2015-08-28/
     2015-08-26_H1MICH_freeswingingdata.xml

(7) Does not Exist

(8) /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/FreeSwingMich/2015-08-28/
     2015-08-28_H1SUSITMX_L2_State2_MICH.xml

(9) /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/FreeSwingMich/2015-08-28/
     2015-08-28_H1SUSITMX_L2_State2_XARM.xml

(10) /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/FreeSwingMich/2015-08-28/
     2015-08-28_H1SUSETMX_L3_HVHN_XARM.xml

(X) /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/FullIFOActuatorTFs/2015-08-28/
     2015-08-28_H1SUSETMY_L3toDARM_LVLN_LPON_FullLock.xml

(Y) /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/FullIFOActuatorTFs/2015-08-28/
     2015-08-28_H1SUSETMY_L1toDARM_FullLock.xml
     2015-08-28_H1SUSETMY_L2toDARM_FullLock.xml

(Z) /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Measurements/FullIFOActuatorTFs/2015-08-28/
     2015-08-28_H1SUSETMX_toDARM_FullLock.xml

Wish us luck on tomorrow's measurement suite; hopefully it'll be the last time for while!
Comments related to this report
kiwamu.izumi@LIGO.ORG - 14:53, Thursday 03 September 2015 (21190)

Just for booking purpose.

In addition to the measurements that Jeff posted, I have done a Pcal Y sweep and DARM open loop measurements in a frequency band of [7 800] Hz using Darkhan's template. The data can be found at:


aligocalibration/trunk/Runs/ER8/H1/Measurements/PCAL/2015-08-28_PCALY2DARMTF_7to800Hz.xml

aligocalibration/trunk/Runs/ER8/H1/Measurements/DARMOLGTFs/2015-08-28_H1_DARM_OLGTF_7to800Hz.xml

H1 CAL
kiwamu.izumi@LIGO.ORG - posted 23:15, Friday 28 August 2015 - last comment - 16:37, Saturday 29 August 2015(21004)
DARM open loop template updated

The dtt template for DARM open loop measurement has been updated to take the new elliptic filter (alog 20612) into account. This covers a frequency band of 7-1200 Hz. Additionally, a few frequency points are slightly shifted to avoid notchy places.

The dtt file is saved in SVN at

aligocalibration/trunk/Runs/ER8/H1/Measurements/DARMOLGTFs/2015-08-28_H1DARM_OLGTF_7to1200Hz.xml

Images attached to this report
Comments related to this report
kiwamu.izumi@LIGO.ORG - 16:37, Saturday 29 August 2015 (21012)

Also, the frequency vector for Pcal Y sweep is adjusted to the one for the new DARM template. I could not fully test it out because of a lockloss in the middle of the measurement. However, since I interpolated the amplitude from 2015-08-17_PCALY2DARMTF_logscale.xml, the signal-to-noise ratio should be as good as it in principle. The new Pcal Y template is saved in SVN at

aligocalibration/trunk/Runs/ER8/H1/Measurements/PCAL/2015-08-29_PCALY2DARMTF_7to1200Hz.xml

H1 SEI (ISC)
hugh.radkins@LIGO.ORG - posted 16:58, Friday 28 August 2015 (20999)
HAM1 HEPI Coherences to ReflA re Kissel/Dwyer 20664

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. 

Images attached to this report
H1 CAL (CAL)
darkhan.tuyenbayev@LIGO.ORG - posted 16:25, Friday 28 August 2015 (20998)
Fixed Epics values used for calculation of DARM time-varying parameters (using H1 DARM model for ER7)

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

H1 SEI (CDS, PEM)
evan.hall@LIGO.ORG - posted 16:06, Friday 28 August 2015 - last comment - 21:08, Sunday 30 August 2015(20997)
DMT viewer template for STS BLRMS

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?]

Images attached to this report
Comments related to this report
daniel.sigg@LIGO.ORG - 21:29, Friday 28 August 2015 (21002)

What was wrong with the old plot?

evan.hall@LIGO.ORG - 22:09, Friday 28 August 2015 (21003)

The STS is more sensitive than the Güralp in the frequency band where we typically watch for earthquakes (30 mHz to 100 mHz).

daniel.sigg@LIGO.ORG - 21:08, Sunday 30 August 2015 (21040)

Looks like we should keep the old plot then, since everyoe already knows it.

H1 General
nutsinee.kijbunchoo@LIGO.ORG - posted 16:00, Friday 28 August 2015 (20982)
Day Ops Summary

(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.

Images attached to this report
LHO FMCS
bubba.gateley@LIGO.ORG - posted 15:03, Friday 28 August 2015 (20996)
Beam Tube Enclosure Joint Repair on the X-Arm
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.   
LHO FMCS
bubba.gateley@LIGO.ORG - posted 14:52, Friday 28 August 2015 (20993)
Staging building chiller
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.

 
H1 CDS
james.batch@LIGO.ORG - posted 14:51, Friday 28 August 2015 (20995)
Added script to bundle medm screens for remote access
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.
H1 SEI
hugh.radkins@LIGO.ORG - posted 14:45, Friday 28 August 2015 - last comment - 14:47, Friday 28 August 2015(20992)
STS2-A returned from Quanterra--I don't know...

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?

Images attached to this report
Comments related to this report
hugh.radkins@LIGO.ORG - 14:47, Friday 28 August 2015 (20994)

Ignore the Title stating Huddle and cables switched.  Units are in home position on nominal cables.

H1 CAL (AOS, CAL)
darkhan.tuyenbayev@LIGO.ORG - posted 13:34, Friday 28 August 2015 (20991)
LHO Pcal EndX and EndY calibration measurements were taken (analysis to follow)

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:

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:

Record sheet papershots are attached to this alog.

Images attached to this report
H1 CAL (ISC)
jeffrey.kissel@LIGO.ORG - posted 00:45, Tuesday 25 August 2015 - last comment - 21:41, Friday 28 August 2015(20850)
ALS DIFF VCO / PLL Open Loop Gain Measured Again, Points back to Nominal 1.6 Hz Pole
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.
Non-image files attached to this report
Comments related to this report
kiwamu.izumi@LIGO.ORG - 21:41, Friday 28 August 2015 (21001)

Since we propagate the uncertainty in the estimation of the poles and zeros to the entire diff calibration, we needed to do a quantitative fitting. So we did it using LISO. Here is the resultant plot:

 

The below are the raw output from LISO. We will propagate these errors throughout the ALS Diff calibration.

########## fitting results ###############

  
It seems that parameter 'delay' has only a little influence on the fit.
  Suggestion: disable the 'param delay' instruction.
Correlation matrix (using fast derivatives)
       pole1:f zero0:f  factor   delay
pole1:f       1
zero0:f   0.435       1
 factor  -0.909  -0.104       1
  delay -0.00739  -0.022 1.01e-11       1

Best parameter estimates:
pole1:f =  1.5812454061 +- 8.509m (0.538%)
zero0:f =  40.8398688169 +- 114.7m (0.281%)
factor =  1.8947798127M +- 8.898k (0.47%)
delay =  1.2910415204u +- 84.71n (6.56%)

Final chi^2=1.87823

 

 

The fitting code can be found in SVN at

aligocalibration/trunk/Runs/ER8/H1/Scripts/ALSDiff/fit_diff_pll_olgtf_20150824.fil

Images attached to this comment
LHO VE
kyle.ryan@LIGO.ORG - posted 17:21, Friday 21 August 2015 - last comment - 18:17, Friday 28 August 2015(20765)
Beam Tube ion pump coupled to port hardware at Y2-8
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)
Non-image files attached to this report
Comments related to this report
kyle.ryan@LIGO.ORG - 18:17, Friday 28 August 2015 (21000)
Upon reconsideration the BT valve is experiencing a minimum of 55ft*lbs as a result of having mounted the 8" gate valve to the reducing Tee before having coupled the ion pump to the 8" valve
H1 ISC
evan.hall@LIGO.ORG - posted 10:13, Friday 14 August 2015 - last comment - 12:07, Friday 04 September 2015(20526)
Sensing noises in the OMC DCPDs

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:

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.

Non-image files attached to this report
Comments related to this report
rana.adhikari@LIGO.ORG - 12:07, Friday 04 September 2015 (21214)

* What is the reasoning behind the updated suspension thermal noise plot?

* Its weird that cHard doesn't show up. At LLO, cHard is the dominant noise from 10-15 Hz. Its coupling is 10x less than dHard, but its sensing noise is a lot worse.

evan.hall@LIGO.ORG - 10:59, Wednesday 19 August 2015 (20680)

I remade this plot for a more recent spectrum. This includes the new EOM driver, a second stage of whitening, and dc-lowpassing on the ISS outer loop PDs.

This time I also included some displacement noises; namely, the couplings from the PRCL, MICH, and SRCL controls. Somewhat surprising is that the PRCL control noise seems to be close to the total DCPD noise from 10 to 20 Hz. [I vaguely recall that the Wipfian noise budget predicted an unexpectedly high PRCL coupling at one point, but I cannot find an alog entry supporting this.]

Non-image files attached to this comment
evan.hall@LIGO.ORG - 14:33, Friday 21 August 2015 (20758)

Here is the above plot referred to test mass displacement, along with some of our usual anticipated displacement noises. Evidently the budgeting doesn't really add up below 100 Hz, but there are still some more displacement noises that need to be added (ASC, gas, BS DAC, etc.).

Non-image files attached to this comment
evan.hall@LIGO.ORG - 16:25, Monday 24 August 2015 (20832)

Since we weren't actually in the lowest-noise quad PUM state for this measurement, the DAC noise from the PUM is higher than what is shown in the plot above.

If the updated buget (attached) is right, this means that actually there are low-frequency gains to be had from 20 to 70 Hz. There is still evidently some excess from 50 to 200 Hz.

Non-image files attached to this comment
evan.hall@LIGO.ORG - 13:04, Friday 28 August 2015 (20990)

Here is a budget for a more recent lock, with the PUM drivers in the low-noise state. The control noise couplings (PRCL, MICH, SRCL, dHard) were all remeasured for this lock configuration.

As for other ASC loops, there is some contribution from the BS loops around 30 Hz (not included in this budget). I have also looked at cHard, but I have to drive more than 100 times above the quiescient control noise in order to even begin to see anything in the DARM spectrum, so these loops do not seem to contribute in a significant way.

Also included is a plot of sensing noises (and some displacement noises from LSC) in the OMC DCPDs, along with the sum/null residual. At high frequencies, the residual seems to approach the projected 45 MHz oscillator noise (except for the high-frequency excess, which we've seen before seems to be coherent with REFL9).

Evidently there is a bit of explaining to do in the bucket...

Non-image files attached to this comment
evan.hall@LIGO.ORG - 10:06, Friday 04 September 2015 (21210)

Some corrections/modifications/additions to the above:

  • I updated the optical gain and DARM pole using the pcal like at 331.9 Hz; from this line I find the transfer function from the TX PD into DCPD sum is (1.69 − 1.59i) mA/pm, which works out to an optical gain of 3.19 mA and a DARM pole of 353 Hz. I think Kiwamu may have a different number from his pcal sweep, so there might be some reconciliation to do.
  • I now compensate the extra 10 kHz pole that Kiwamu found in the readout chain of the DCPDs.
  • I remade the quantum noise curve for 23 W, and with a more realistic estimate of the losses. In addition to the 87 % quantum efficiency, I include 14 % readout losses that Lisa has already tabulated: we expect 96.5 % transmission through the OFI, 93 % transmission through the OMC, 99% reflection from OM3, and (according to Dan) 97 % mode matching into the OMC. This results in a quantum noise curve that is 6.6×10−20 m/Hz1/2 at 1 kHz. The DARM pole predicted by GWINC is 360 Hz or so (slightly higher than what I extracted from pcal).
  • Previously, I had tuned the arm losses in GWINC to give a recycling gain of 40 W/W. In light of Sheila's analysis, this is too optimistic; usually our recycling gains are more like 36 to 37 W/W. In GWINC, this amounts to tuning the arm losses to 90 ppm (per arm), which gives a gain slightly in excess of 37 W/W.
  • The null stream is 5 % – 7 % higher than the GWINC curve, so either some parameter is mistuned or we need to be looking for some extra readout loss.
  • I replaced the GWINC suspension thermal noise curve with a (hopefully) more accurate curve that I got from Sheila.
  • I replaced the oscillator noise trace (which was flat in DCPD photocurrent) with a trace based on the TF that Stefan and I took. I still assume the underlying noise contribution is flat in RIN, at a level of 3.5×10−8 mA/Hz1/2. This trace will become less relevant since the excess oscillator noise now appears to be gone.
  • I added gas noises. Squeeze film damping was calculated after T0900582 using the nominal parameters (our end station gauges read 1×10−8 torr, and I've assumed the dominant species is molecular hydrogen). For residual gas, I again assume the species is molecular hydrogen, and the arm pressure is taken to be 5×10−9 torr (which is a rough average of the arm gauges).
  • The ASC trace contains only the dHard and BS loops. I drove in cHard, but even after driving far, far above the ambient noise floor I could not make excess noise appear in DARM.

Of course, the budgeted noises don't at all add up from 20 Hz to 200 Hz, so we are missing something big. Next we want to look at upconversion and jitter noises, as well as control noise from other ASC loops.

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