Elli, Sheila, Alexa, Rana, Evan

Since we haven't been able to reliably transition ALS COMM to sqrt(TRX+TRY), we decided we'd back off a bit and try the transition with a single arm only (i.e., no DRMI).

The sequence that we found worked for us is as follows:

• Adjust the ALS COMM VCO offset to −100 Hz_green.
• Engage the sqrt(TRX) path with a 1 Hz pole and a 40 Hz zero, an offset of −0.7 ct in TR_CARM, and an overall TR_CARM/REFLBIAS/REFLDCBIAS gain of 80 ct/ct. The common-mode board has an input gain of 0 dB (ALS COMM has an input gain of −4 dB). Addtionally, we have the usual filters engaged in TR_CARM/REFLBIAS/REFLDCBIAS:
  • a 1 kHz pole and a pair of complex zeros at 35 Hz (with a Q of 1) which are meant to make sqrt(TRX+TRY) fall off as 1/f out to high frequency
  • a 1.6 Hz pole and a 40 Hz zero which imitates the response of the ALS COMM VCO.
• Turn off the COMM VCO frequency servo. Tune the VCO voltage so that the sqrt(TRX) output (as monitored via REFLDCBIAS_OUT) is close to zero.
• Engage a 0 Hz pole and 1 Hz zero in the sqrt(TRX) path, so that sqrt(TRX) has a true integrator.
• Turn off the ALS COMM PLL boost (pole at 1.6 Hz, zero at 40 Hz).
• Ramp down the analog gain of ALS_COMM on the summing node board to −32 dB. Then switch off the input.

For most of this process we had a GPIB-controlled SR785 hooked up to the common mode and summing node boards in order to monitor the relative strengths of the ALS COMM and sqrt(TRX) signals. For the excitation we drove EXC A on the common-mode board; for ALS COMM we monitored TEST1 on SUM A, and for sqrt(TRX) we monitored TEST2 on SUM A. This was incredibly helpful for sorting out how to properly shape sqrt(TRX) and how to engineer a stable crossover during the transition.

Sudarshan, Darkhan, Rick, Sheila, Rana, Evan

Summary

For a little while we've been worried that excess RIN might be causing some of the difficulty in transitioning the CARM sensor from ALS COMM to sqrt(TRX+TRY). Based on the measurements here, it appears that RIN from the PSL is not an issue. However, we're continuing to investigate whether the RIN further downstream of the PSL will cause us issues.

From 1 Hz to 100 kHz, the rms RIN is about 5×10⁻⁴. For a power recyling gain of 30 W/W and a CARM offset of 300 pm, we expect sqrt(TRX+TRY) to have a value of 1.7 ct and a slope of 5.6×10⁻³ ct/pm. The RIN therefore appears as a 8.5×10⁻⁴ ct rms fluctuation, which propagates forward to a 0.15 pm rms fluctuation in CARM.

Details

Sudarshan, Darkhan, and Rick spent some time diagnosing the health of the first ISS loop (using ISS PDB as the in-loop sensor, and ISS PDA as the out-of-loop sensor). They turned down the gain of the OLTF by approximately 10 dB in order to reduce the UGF from 80 kHz or so to more like 25 kHz (so that it sits right in the middle of the loop's phase bubble, where there is about 45 degrees of phase). The OLTF is shown in an attachment. Next, we took spectra of the in- and out-of-loop sensors. The dc voltage on both was 2.2 V.

Initially there was some uncertainty (and perhaps there is still some uncertainty) about the frequency-dependent shaping of the ISS PD signals. Based on the schematic in D1001998, I claim the shape is a dc gain of 0.2 V/V, two zeros at 0.07 Hz, two poles at 3.1 Hz, and a pole at 135 Hz.

At around 3:30 this morning, the ETMX T240s started to drift to some large values.  This morning we were having trouble locking the X arm with green light, and noticed that the REFL CNTRL output was huge, indicating that the cavity length was changing by ~20 um in about 10 seconds.  We looked at the ISI screens, saw that the T240 mons were red.  After interupting Jeff's Saturday morning errands, we decided to try zeroing the T240s by turning on FM6 (labeled AutoZ) in the T240 X filter banks, when we did this the ISI tripped.  It started to Isolate, the outputs of the T240s were still large but not as large as they had been, stage 2 watchdog tripped, then it isolated and the cavity motion is much much less.  

The firt attached screen shot shows the green laser control signal roughly calibrated in um, you can see the abrubt change when we tripped the ISI and the much smaller fluctuations after.  The second screen shot shows a trend of the outputs over the last two days.  

model restarts logged for Fri 23/Jan/2015
2015_01_23 00:08 h1fw0
2015_01_23 00:41 h1fw0
2015_01_23 01:22 h1fw0
2015_01_23 03:26 h1fw1
2015_01_23 13:42 h1fw0
2015_01_23 15:29 h1fw1
2015_01_23 16:30 h1fw1
2015_01_23 19:38 h1iscey
2015_01_23 19:40 h1dc0
2015_01_23 19:42 h1broadcast0
2015_01_23 19:42 h1fw0
2015_01_23 19:42 h1fw1
2015_01_23 19:42 h1nds0
2015_01_23 19:42 h1nds1
2015_01_23 20:02 h1fw0
2015_01_23 20:04 h1dc0
2015_01_23 20:04 h1iscex
2015_01_23 20:14 h1iscey
2015_01_23 20:24 h1broadcast0
2015_01_23 20:24 h1dc0
2015_01_23 20:24 h1fw0
2015_01_23 20:24 h1fw1
2015_01_23 20:24 h1nds0
2015_01_23 20:24 h1nds1

Several unexpected fw restarts. ISC EY/EX changes with related DAQ restarts. The last DAQ restart failed and had to be completed manually. Conlog frequently changing channels report attached.

Sudarshan, Rick, Darkhan

Pcal EY is running at full power with 2W beam pushing the end test mass and Optical Follower servo engaged. The loop gain is set at 24dB with refrence offset at 5 V. We will let it run over the weekend and characterize the PDs on Monday.

With the addition of the WFS/auto-centering/tidal the CPU cycles in end station isc models have gradually increased to the point where we saw IPC errors in the lsc of ~1000err/sec from ex and ~10000err/sec from ey. The ey problem was compounded by adding the temporary oscillators last Wed. This mainly effects the transmitted red power which is sent to to the corner for locking. We removed the temporary oscillators, the other 2 oscillators we never used, as well as the WFS path to the input PTZs. This reduced the IPC errors as seen by the lsc to 1-2err/sec (both ex and ey). There are still ipc errors from the lsc to the sus (DARM_ERR) around 10err/sec (unchanged).

The DAQ did not restart cleanly after the evening's h1iscey and h1iscex model changes. After checking for duplicate channels in the DAQ configuration (of which there were none) I manually restarted monit on h1dc0. The DAQ started cleanly this time.

I did some tests on the bsc chambers this morning 

• closed stage 1 and 2 Rz controls on ETMX ETMY ITMX ITMY with 750mHz blend filters ("T750mHz" in FM2) - first and second screenshots-

They have been left on during the day (from ~19:00 UTC) to eventually get some offline data. The oplev yaw see some minor improvement for ITMx and ETMx, but nothing for the other two chambers (first screenshot). The references are without the Rz loops running. The second screenshot is for the cps afficionados. 

• open st2 rz and reduced the stage 1 rz blend to 45mHz to observe the z->rz coupling -third screenshot-

the references are with st1 rz closed at 750mHz. When the blend is low -45mHz-, st2 gs13 signal is better between 0.2Hz and 5Hz but worse below 0.2Hz. The st1 cps see a large relative motion with the ground at low frequencies. 

I didn't have a chance to try the last configuration with the subtraction path engaged.

The dtt templates are under /ligo/svncommon/SeiSVN/seismic/BSC-ISI/H1/{chamber}/Data/Spectra/Isolated

This entry corrects log 16052. The plots there were given the wrong DOF titles. While at it, I added plots comparing stage 1 to stage 2 TFs. The model matches well around the resonances here, but has the wrong slope at higher frequencies.

The model is located on the svn at

/ligo/svncommon/SeiSVN/seismic/BSC-ISI/Common/BSC_ISI_Model/N4SID_Model/L1BS/BuildFullL1BSmodel.m

To compare the model to data, run

/ligo/svncommon/SeiSVN/seismic/BSC-ISI/Common/BSC_ISI_Model/N4SID_Model/L1BS/CompareModel_to_data.m

J. Kissel, H. Radkins, J. Warner, A. Pele

Here's a recap of the the week's progress, contrasted against last week's to-do list; revising it for the next week or two. Arnaud's back to LLO tomorrow, Krishna's in for next week.

Improve The Chamber Noise Performance:  
     All Chambers                                                 Benefit to IFO
     - ST 01 L4C Feed Forward (all 6 DOFs),             improve 1 to 10 [Hz] performance -- No progress yet
DONE - Sensor correction gain matching (all 3 DOFs),    improve 0.08 to 3 [Hz] performance (see LHO aLOG 16208)
         - Turned into "Investigate factor-of-2 problem with Corner Station STS B's X Channel" (see LHO aLOG 16237)
     - Assess whether switching to differential pressure affects platform noise performance -- suddenly interesting, may impact sub-0.1 [Hz] Yaw (see LHO aLOG 16231)
         - Measure HEPI Pump Servo Plant
         - Tune Pump Servo PID loop
         - Differential Pump Pressure signals are noisy possibly from poor electrical grounding, fix it if still there after loop tuning

     BSCs Only
     - Z to RZ subtraction,                            reduce BSC optic's yaw below 0.08 [Hz]  
            This has turned into "Close RZ loops on Stage 1 and Stage 2 with high frequency blend filters" but seems to have little to no improvement. Continue Assessment.
     - Discuss / Assess closing the rest of ST2 isolation loops
     - Assess performance of loops with GS13s in low gain vs. high gain (are we ADC noise limited?)
     - Implement Slow MICH,                        reduce MICH velocity, improving lock acquisition -- No progress; waiting for Ryan DeRosa
DONE - Finish ITM HEPI Z to RX/RY Tilt Decoupling,     reduce BSC optic's yaw below 0.08 [Hz] (see LHO aLOG 16118)

     HAMs Only
DONE - HAMs 2,3,4,5 Isolation Loop Gain Increase       improve 0.5 [Hz] to 20 [Hz] performance (see LHO aLOG 16214)
     - Continue HAM3 0.6 [Hz] feature investigation        improve 0.6 [Hz] performance
            No progress on *solving* the problem, but some investigation on finding a better compromise (see LHO aLOG 16196

Improve the Maintainability / Extensibility:
     - BSC-ISI Noise Budget Model -- Good Progress; see G1500081
     - HAM-ISI Noise Budget Model -- No progress yet; sort of waiting for BSC-ISI budget to be more developed
     - HEPI Noise Budget Model -- No progress yet
     - Assess guardian vs. watchdog robustness of bringing all chambers to OFFLINE from FULLY_ISOLATED -- No progress
     - Put MATCH OUTPUT channels on Sensor Correction overview screen -- No progress
DONE - Storing more than just RZ on HEPI alignment (see LHO aLOG 16207, LHO aLOG 16191)
     - Switch ETMX to using differential pressure signal
     - Include closing ST1 and ST2 RZ loops into guardian
     - Include gain switching on all Guardians
     - Get ISI system under SDF system configuration control
DONE - Get HPI system under SDF system configuration control (see LHO aLOG 16217)
DONE - Install DeRosa filters into NXT blend filter banks, such that blend switching may eventually work (see LHO aLOG 16200)
     - Figure out how to make blend switching code work with multi-bank filters

Relegated to installation AFTER 2 hour lock:
     - Hook IOP SWWD signals up to ISI USER watchdog
     - Install HEPI saturable integrators
     - Remove HEPI / ST0 L4C Sensor Correction path from ISI models

8:48 Keita to EX working on ISCTEX

9:01 Keita done

9:03 Jim and Arnaud to MSR and LVEA looking at cabling

9:05 Gerardo to LVEA decoupling vacuum pump

9:11 Sudarshan and Fil to LVEA working on PEM mics

9:27 Gerardo done

10:30 Manny and Essence to MY 3IFO inventory

10:36 Sudarshan and Fil done

J. Kissel, H. Radkins

We'll fill out with more plots, data, and information later, but we've found that the newly installed differential pressure readout in the corner station HEPI pumps is coherent with noise in the BSC HPI L4Cs between 0.1 and 1 [Hz] in Z, and 0.01 - 0.1 [Hz] in RZ. I attach results for the Beam Splitter's tank.

**Edit -- Page Three had terribly confusing labels, I've now fixed the plot to reflect the information correctly -- its the rotational DOFs, which are, of course, in [rad/rtHz].

Jeff wanted me to see if I could find some cavity signals to assess the performance of the corner station ISI's after my work on the HAM's on Tuesday. The commissioners gave us a bunch of channels to look at, but it looks like there haven't been any DRMI lock stretches long enough for us to get good spectra. I've attached trends of the 4 channels we want to look at. SRCL, PRCL and MICH all have whitening filters (starting at 1hz) that would need to be divided out. Kiwamu said that  LSC-POPAIR_B_RF18_I_ERR_DQ is above 600 counts when DRMI is locked.

• LVEA free-reign time moved up to 10am to allow for more commissioning time.  Check with operator/commissioners if you need to be in VEAs after 10am.
• Tuesday maintenance activities will be kept to a minimum to allow for less commissioning downtime.
• CDS at MY for 3IFO inventory
• CDS PEM mic work continues
• SUS needs to keep working on SDF
• PCal analyzing data from yesterday's work at EY

The following microphones were powered up in the corner station:

PSL, HAM2, HAM3, Vertex, Y arm spool and CER.

Each microphone power box was tested to verify both channels are working.

Filiberto C. and Sudarshan K.

Evan, Alexa, Elli, Sheila, Rana,

• Evan changed the gain on the END Y TR PD to 20dB, while the X end 1 is still at 0dB (alog 16211)
• We realized that with our better recyling gain, the locking offset and gain we used last night were not sensible.  We are not using an offset in sqrt(TRX+TRY) of -1.7, which would put us at 300 pm if the recylcing gain is 30, similiar to the CARM offset that we used before.  We also estimated that the calibration into picometers should be changed from 312 to 180.  (this is the to_pm FM in TR_CARM)
• Alexa realized that the res G filter to supress 1 Hz noise in ALS DIFF was not on, turning this on reduced the RMS of ALS by about a factor of 10, helping us to stay in the linear range of TR CARM.
• We have been stable in the state PREP_TR CARM for 10 minutes or so.  We have been able to turn the gain of the ALS signal down to -11dB on the common mode board, while the TR CARM input was at a gain of 4dB.  
• We changed the low frequency boost in LSC-REFL BIAS, we are no longer engaging FM6 (a true integrator with a zero at 1 Hz).  We also changed FM5 so it is no longer a true integrator, it now has a pole at 1Hz and is turned on in PREP_TR_CARM.  We have also stopped using the lead filter in FM8, we have plenty of phase without it.  
• We measured the cross over in ALS COMM to be at 50 Hz, with 45 degrees of phase margin.

We think that we are loosing lock due to some 12-15 Hz noise in CARM which is non stationary.   We watched the spectrum of CARM locked on ALS with and without DIFF locked, and saw that the non stationary noise is only there when DIFF is locked.  We then looked back at our ALS DIFF design (alog 15025) and decided to reduce the gain by 35%. This has reduced the gain peaking, but we still have nonstationary noise in CARM.  

lock loss times: 1:44:20 UTC, 3:01:27 UTC Jan 23rd UTC lock loss durring swept sine excitation 3:55 UTC

I have turned up the preamp gain on the LSC-Y_TR photodiode (a PDA100A on ISCTEY) from 0 dB to 20 dB. The BS immediately before this PD is a BS1-1064-50-2037-45P.

The LSC-TR filter banks have been adjusted as follows:

• LSC-Y_TR_A_LF: gain changed to 0.0185 from 0.185; offset changed from -30 to -40
• LSC-X_TR_A_LF: offset changed from -180 to -171.

Last week, sts correction gains were measured and calculated on HAM4/5/6 to improve the CPS sensor correction. We measured them today for the remaning chambers.

For the BSC chambers, we locked the platforms to the ground by increasing the blends to 750mHz (cf alog) and turned off the sensor correction. We measured the ratio between the T240 (stage 1) and the STS (ground) signal (should be 1 with the platform moving with the ground). The same measurement was also carried out between STS and L4C for hepi, since IPS sensor correction is used for the Z DOF.

All the measurements using the corner station STS B as input to the sensor correction (ITMX, BS, ITMY) show a factor of two mismatch with the hepi and platform sensors in the X DOF only. There is certainly a calibration error with the STS B seismometer. I checked the calibration filter in the input filter banks and it looks correct (10.17 nm/s /cts). We should investigate more. The other chambers and dofs need a relatively small correction. 

The ISI gains (T240/STS for BSCs and GS13/STS for HAMs) are 

The BSC - HEPI gains (L4C/STS) are

Attached are examples of the transfer functions for ITMY 

To calculate the gains I wrote a script for the bscs in a similar fashion as Sebastien's : it is called BSC_gain_matching_calculation(IFO,Chamber,start_time,duration) located under /ligo/svncommon/SeiSVN/seismic/BSC-ISI/Common/Misc. The results above were obtained using the following parameters : 

start_time=tconvert('01/22/2015 15:35') ;
duration = 45*60 ;