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:
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
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.
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.
I've looked at this a bit more, but i can't find anything obvious. At ~11:40 UTC, something agitated the ISI and it stayed that way until 21:30 when Sheila tripped the ISI ( T240 time series trend shown in first screenshot) The ETM optic was in a similar state, and returned to normal after the ISI tripped. The ground sensors don't show anything (second plot, reference is from 8:00 UTC, active is from 12:00), and I didn't see any evidence that the ISI isolation loops were ringing (last screen shot, I only show a few, but I looked at them all).
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
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.
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.
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,
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
The first attachment is of a REFLBIAS transfer function when we had partially transitioned between TRXY and ALS COMM (CMB IN1 Gain was 4, and CMB IN2 gain was -11). When we measured this TF we had not engaged the FM5 boost. Still, this does not look correct ...
The second attachment is of ALS DIFF and CARM spectra. It seems we had some gain peaking in ALS diff, which motivated us to lower the gain as Sheila mentioned. This reduced the peak in CARM, but did not eliminate it.
Here are some more lock loss times for last night:
23/1/15 00:03:03 UTC
23/1/15 01:14:01 UTC
23/1/15 01:43:45 UTC
23/1/15 02:17:01 UTC
Attached is lockloss plot at 23/1/15 00:03:03 UTC. LSC-REFL_SERVO_IN2GAIN was turned down at 00:03:03 -26 seconds. Lock was lost 26 seconds later. CARM noise dropped once the gain was turned down. Also attached is a power spectrum of CARM signals before and after turning down the gain. REfs 0 and 1 are before, refs 4 and 5 are after. Puzzlingly, the high frequency noise increased after the ALS gain was turned down.
Here are some other lock loss plots from yesterday. The first one shows that the ALS Y glitch caused one of our locklosses, the Y arm transmission went to 0, with the charachteristic glitch in Y REFL CNTRL, as seen in alog 15242 and 15402. We think this was bad luck, and a reminder that these glitches are a problem.
The other lock losses were less conclusive so far, I've attached a plot that shows that as the gain of the ALS path is ramped down on the common mode board we have large glitches in CARM, however the lock survives this and drops a few seconds later.
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:
Somehow these values were overwritten with the old values around 2015-01-24 03:37:00 UTC. I've restored the new values.
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
X | Y | Z | |
HAM2 | 1.036 | 0.995 | 0.877 |
HAM3 | 0.976 | 0.958 | 0.812 |
ETMX (T240 for gnd sensor) | 1.114 | 1.106 | 1.105 |
ETMY | 0.985 | 0.974 | 0.995 |
ITMX | 1.964 | 0.976 | 0.993 |
ITMY | 1.982 | 0.984 | 0.993 |
BS | 1.99 | 0.986 | 0.994 |
The BSC - HEPI gains (L4C/STS) are
X | Y | Z | |
ETMX | 1.110 | 1.107 | 1.091 |
ETMY | 0.998 | 0.991 | 0.969 |
ITMX | 2.167 | 1.063 | 0.972 |
ITMY | 2.011 | 1.006 | 0.963 |
BS | 2.09 | 1.055 | 0.924 |
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 ;
The sensor correction matching gains were changed to their new values for the BS ITMX and ITMY in the X dof. The pdf attached are comparing the X platform motion before/after the change, showing improvement (x~2) in the 300mHz 700mHz band.
I confirmed that the factor of two mismatch described in the log above comes from the STS B, looking at the comparison of the three ground seismometers (X dof) of the corner station, see attached screenshot.
It looks like the problem is in the B STS or associated cabling. I took spectra of the raw ADC signal and the B seismometer shows half as much X signal (ADC channel 26 on attached plot) as the other 2 STS's. Arnaud and I went out to check the cabling at the rack, everything is tight there. We are doing measurements with the ITM's right now, so we didn't go out to check the cable on the pod.
I looked though the trends and science channels, and it looks like the auto center on the B STS was pushed at 8:30 am local on Dec 23rd, 2014 and the X channel didn't recover properly. On the first attached trend you can see that before the alleged button push (alleged because there are no logs, I'm just guessing, second trend shows what looks like an auto-centering sequence though) the X channel showed more signal, then after less signal. Y channel looks roughly the same before and after. Attached spectra (3rd png) shows overall spectra is very different, solid red is before, dashed green is after.
And if anyone is looking for the freshest copy of the 40m GPIB scripts, they are maintained by Eric Quintero on github: https://github.com/e-q/netgpibdata