Switch HAM2 ground sensor from B to A.
All HAMs running X Y & Z sensor correction from ground to ISI, except HAM3 is doing Z from the Ground to HEPI.
All BSCs (Corner Station) running X & Y from ground to ISI Stage1 and Z from ground to HEPI.
HAM2 HAM3 HAM4 HAM5 HAM6 ITMY BS ITMX BSC1 BSC2 BSC3
Added 225ml of water to topped off the diode chiller water level ahead of the holiday break.
Elli, Evan, Thomas, Kiwamu, Stefan First we made sure we can still run on the 3f diodes with WFS on: - After reconnecting REFLAIR_B and removing the beam dump that worked without a hitch - same WFS gains as coded for DRMI. Next we wanter to check the PRMI - first on SBs: - We temporarily turned of the WFS and Kiwamu simply kicked out the SRM by misaligning it - the PRMI stayed locked. - So we simply turned on all WFS with the same gains as DRMI (without the SRCL loops of course). They worked just fine. Finally we locked the PRMI on the carrier. - There we had to change the WFS gain for PRC1, PRC2 and MICH. Those 3 loops were then simply closed. - We had to slightly lower the MICH_P gain, as we were developing an oscillation. - Kiwamu will post a PRC recycling gain measurement form that data.
Bubba noticed this error while he was in the chiller yard -> I will investigate tomorrow in the daylight -> Air at CP1 LLCV feels dry still
Kyle, Gerardo Finished rough pumping Y-end -> Switched to turbo (backed by QDP80) -> local scroll backing pump has a relay issue that needs to get sorted before it can substituted for QDP80 pump Kyle Began rough pumping X-end (blow down dewpoint -16C) -> Will finish roughing tomorrow and switch to turbo in the afternoon
If the commissioners could turn off all the sensor corrections when they are done tonight, it would be greatly appreciated as we continue to debug the HAM3 problems. Jim has a scripts, Jim's log, to turn these all on or off. I'll set this up ready on opsws1. Additionally, we need to turn off the HAM3 HEPI Sensor correction which Jim's script does not address. Please ramp down the H1:HPI-HAM3_SENSCOR_Z_FIR_GAIN to turn this off. Thank ya much.
LVEA: Laser Hazard Observation Bit: Commissioning 09:10 Cris – Delivering garb to End-X 09:10 Karen – Cleaning in the LVEA 09:37 Gerardo – In LVEA doing viewport checks 09:37 Hugh & Mitch – To unlock HEPI at End-Y 09:47 Aaron – PEM cabling work between HAM2 and Beer Garden 09:50 Travis – Open the High Bay rollup door in LVEA to bring in equipment from the end stations 10:22 Hugh & Mitch – Back from End-Y - HEPI is now unlocked 10:25 Bubba – Going to End-X to check on cleanrooms 10:51 Karen – Going to End-Y to check on garb and clean 11:10 Bubba – Shutdown cleanrooms at End-Y and turn on heaters 11:30 Karen – Finished at End-Y 12:37 King Soft Water on site to drop off parts 13:17 Aaron – Pulling OpLev cables in the LVEA 14:54 Robert S. – Delivering equipment to End-Y 15:40 Daniel – Transitioning both End-X and End-Y to laser hazard
Rich, Hugh, Fabrice:
Continuing the investigation to solve HAM3 noise issues. Last tests on Fridays doing the sensor correction to HEPI instead of ISI show that the noise line is still visible in the CPS, but not in the GS13. Rich suggested it might mean that the noise is introduced in the sensor correction channels (still disturbing Stage 0, but rejected by Stage 1 isolation). So we have looked at the coherence bewteen the FIR channels:
H1:ISI-HAM2_SENSCOR_GND_STS_X_FIR_IN1_DQ,
H1:ISI-HAM3_SENSCOR_GND_STS_X_FIR_IN1_DQ,
...
H1:ISI-HAM6_SENSCOR_GND_STS_X_FIR_IN1_DQ
for the X, Y and Z directions.
The coherence from HAM2 to the other channels is shown in the plot attached. It is pretty bad in the Y direction, but we don't see the coherence droping at 0.6 Hz. Next step is to look at the output of the sensor correction filters (not sure whether they are in the DAQs, I might need someone on site to look at it)
A separate comment: Hugh and I just checked which ground instruments are used where. It looks like HAM2 uses intrument A, and HAM3 uses instrument B. We probably want those two chambers to use the same sensors. We might want to investigate a bit more on HAM 3 (and fix it!) before we swap.
Here are coherences at the OUT of the Match filter. Results look somewhat similar but with cetain differences to the plots Fabrice put in. In particular, the X & Z coherences don't go as low in frequency. The Y dof does look very similar.
Elli, Daniel, Evan
We tried adding a dc bias to the PSL EOM in order to reduce the RFAM, with little success.
At the top of ISC R1, we inserted a minicircuits bias tee into the 9 MHz drive that goes to the PSL EOM. With a DMM, we measured the input impedance of the 9 MHz drive to be an open, and the input impedance of the analogous point in the 45 MHz drive was 70 Ω. We take this to mean that the 9 MHz drive goes directly to the EOM, with no intervening amplifier.
To see the effect of dc bias, we first hooked up the dc port of the tee to ISC-EXTRA_C_AS_AO_4, which is a slow DAC channel on the ISC rack. We applied ±10 V dc offset while watching the time series of REFL_A 9I&Q, but saw no obvious changes.
So instead, we hooked up the dc port of the tee to LSC-EXTRA_AO_2 (a fast channel) and drove it with a 32700 ct, 444 Hz sine wave. Then we looked for this excitation in spectra of REFL_A RF9I&Q.
Previously (LHO#15681), the RFAM level has been pegged at 1.1×10−3 Wrms/Wdc. That means that the fractional RFAM change that can be effected by this bias tee configuration appears to be something like 1×10−6 / Vbias, which is way too small to be practical.
J. Kissel I've taken a full set of top-to-top transfer functions on H1 SUS ETMX to complete the quick assessment performed on Friday (LHO aLOG 15748) and confirm all is free and good after the recent optic cleaning (LHO aLOG 15744) and door re-install (LHO aLOG 15750). The chamber is still at air, but the doors are on, the ISI is damped, HEPI is floating and position controlled. Results look great. The only thing of interest is that the 2nd pitch mode, previously reported to be a lower frequency than expected (see LHO aLOG 8822) remains low in frequency, and has not changed since the previous assessment. Again, we've controlled this suspension admirably, so no problems. Just one of life's mysteries that remains unsolved. All data, and updated scripts have been committed to the repository (see below for details). ----------------- Raw Data: /ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/ SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_L_WhiteNoise.xml SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_P_WhiteNoise.xml SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_R_WhiteNoise.xml SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_T_WhiteNoise.xml SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_V_WhiteNoise.xml SAGM0/Data/2014-12-22_1710_H1SUSETMX_M0_Mono_Y_WhiteNoise.xml SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_L_WhiteNoise.xml SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_P_WhiteNoise.xml SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_R_WhiteNoise.xml SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_T_WhiteNoise.xml SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_V_WhiteNoise.xml SAGR0/Data/2014-12-22_1720_H1SUSETMX_R0_Y_WhiteNoise.xml Processed and saved .mat files of measurements: SAGM0/Results/2014-12-22_1710_H1SUSETMX_M0_DTTTF.mat SAGR0/Results/2014-12-22_1720_H1SUSETMX_R0_DTTTF.mat Updated scripts: /ligo/svncommon/SusSVN/sus/trunk/QUAD/Common/MatlabTools/ plotquad_dtttfs.m plotallquad_tfs.m
Will run a couple DC tests to insure clearance.
Here are the current ROMs after unlocking HEPI:
1.0mm ROM H1 H2 H3 H4- V1+ V2+ V3+ V4+
0.9mm ROM V2- V4-
0.8mm ROM V1- V3-
0.7mm ROM H4+
broken by people starting to go into the LVEA. Start: 2014/12/22/01:05 Stop: 2014/12/22/17:25 Duration:16h20min We do see O(1%) power drifts, including a step arounbd 8:30am local - presumably due to human activity. We will chase down where this comes from.
Kiwamu pointed out that PSL or IMC fluctuations could be the culprit in the ~1% drop in power build up over the course of 14 hours. I attached some trends that show that the PSL output is the cause of the long term degredation and the jump at ~16:01 UTC.
I also attached the WFS loops that we've closed in the past few days (BS,PR3, PRM, SR3, SRM) to see how they are reacting to the change in power and they seem to not vary much over the course of the night. I've also attached some trends of the WFS/optics that we're not using (RF45 and PR2) to see if the uncontrollled DOFs are also coupled into this power loss, it looks like there might be some of this occuring when comparing thhe WIT sensors on PR2 to the power buildup.
(Doug C and Suresh D.)
This afternoon we replaced the glitchy diode laser (Sl. No. 193) in the BS optical lever with a repaired and thermally stabilised laser (Sl. No. 130-1) which was under observation in HAM3 oplev. The attached plots show the improved performance due to the repairs and stabilisation.
Things to note:
1) Broadband noise injection into pitch has disappeared after swapping the lasers
2) Constant glitching and consequent broadband injection of noise into yaw signals has disappeared after swapping.
3) The RIN has dropped by an order of magnitude at all frequencies
4) The spectrum is stable and does not oscillate between stable and unstable regimes as the temperature in the LVEA changes due to the airconditioners.
Please note that the laser is still approaching a stable operating condition and is under observation for a futher 24 hrs. However its performance over the past six hours is satisfactory.
Distinguishing glitch and operator initiated actions in PIT and YAW signals:
We can distinguish the glitch and operator actions by looking at their spectral signatures. A glitch would cause a rise in spectral amplitude right across the entire frequency range. This would then appear as a white line running vertically (across all frequencies) in the spectrogram. Where as an operator initiated action would have a subsequent suspension damping motion at low frequencies (only).
We can see examples of both in the PIT spectrogram. There are no glitches in the red trace (the spectrogram for that is in bottom panel). This was after about 7PM and folks had already started using the BS oplev for damping. So their initial alignment efforts show up as small steps with an associated low frequency spectral signature.
The blue trace has the classic glitch related signals showing up in pitch. They can be seen starting at 1.3 hrs and going on till 1.4 hrs. I dont think anyone was using the IFO at that time. Since the BS oplev is used for local damping continuously, it is likely that the gliches kicked the optic and caused the activity we see around that time.
The picture is more messy in the case of YAW as we can see from the blue trace and its associated spectrogram (middle panel). The yaw signal seems to be continuously affected by the glitching however the event we saw in pitch at 1.3 hrs can also be seen in yaw. Once again there is no operator related activity in the blue trace while the red trace shows some steps which have an associated low frequency spectral signature (bottom panel). I concluded that they were associated with the initial alignment activity which was going on at that time.
I looked at whether the improvement in the laser quality has resulted in an actual improvement in the BS local damping. There is a tangible improvement in YAW.
1) The Spectrogram of YAW motion shows that the injection of broadband noise into the optic motion in YAW due to glitching has disappeared after the swapping of lasers
2) the Coherence between the witness channel and Oplev channel in YAW shows that we can now extend the servo bandwidth to about 10Hz reliably.
3) The spectrum of yaw motion dropped by a factor of two in the range 1 to 20 Hz. This probably has nothing to do with the laser per se. Probably the pier motion decreased between the two data segments.
Performance check after a week of operation
To see if the laser is still operating safely within the glitch free region, I checked the 1s trend over the past two days. The laser power has a slow drift of about 1% in a day. This is probably a LVEA average temperature related effect. The long term spectrum shows a 1/f shape down to 10^-4 Hz.
And to see the broad band noise I looked at raw signal over the past four hours (256 samples/sec)
The 4hr stretch of raw data spans a period when the oplevs were not used for first 1.4 hour stretch and then were turned on. We can see the suspension resonances damp in the witness channels.
The spectrograms show that there is broad band noise in the optic motion, but it is not due to the laser glitching.
The top panel shows the laser spectrogram and it does not show any broadband noise.
Conclusion:
The laser is performing well, without glitches. All the action we see in the Pitch and Yaw is associated with either human intervention or lock loss events which have kicked the optic.
After looking at the oplev spectra with the OL damping loops on and off, I turned down the yaw gain from 650 ct/ct to 500 ct/ct to reduce the amount of extra noise injected between 1 and 10 Hz. The pitch gain is still 300 ct/ct.
In the attached plot, blue is the spectrum without damping, and red is the spectrum with the new damping gain.
Dan, Kiwamu,
We locked the PRMI on the sidebands to assess the current recyclying gains. The result will be posted later.
We did the initial alignment sequence to get back to a good global interferomter alignment. One thing I have to note is that I had to touch PR3 in yaw by 2 urads in order to recover a high RF power in ALS COMM. It is now back to 3 dBm in the monitor. Also this gave a good spot position on the ALS X camera as it was clipping before I moved PR3. The clipping seems to be fixed now on the camera. I aligned TMSY, ETMY and ITMY using the green light with a hope that they still represent a good IR alignment. After going through all the alignment sequence, the ALS DIFF beatnote came back to a high RF power of about 0 dBm. So I think the global alignment came back to as good as before.
The PRMI was locked very easily by setting LSC_CONFIGS to PRMI_sb_OFFLOADED. Then we aligned the OMs and did OMC scans in order to evaluate the recyclying gains. The data is now under some analysis. After the OMC scan, we attempted to lock the PRMI on the carrier, by simply flipping the sign of the PRCL control sign. We tried different gain settings MICH which uses REFL45Q, but did not get good lock tonight. So, we still don't know the carrier recycling gain.
We locked the PRMI on carrier. The carrier recyclying gain was measured to be 35 at highest. However, since the alignment was not perfect, it probably would go up. To be continued.
After playing with the gain settings, we eventually became able to lock the PRMI on carrier. However the alignment was not stable to keep it locked with high build-up. I think this needs more study to understand what is going on. Anyway, so far, the highest buidl-up in POPAIR_A_LF we had tonight was about 3.5x104 uW. When the simple MICH without power-recycling was locked, POPAIR_A_LF was about 30 uW. Assuming that there is no mode-mismatch and Tp=0.03, we get a recycling gain of 3.5x104 / 30 * Tp = 35.
LSC settings:
Attached are the OMC scan results for a PRMI sideband lock, compared to a scan from a single-bounce beam. The first plot shows the results of three single-bounce scans and three PRMi scans (100 second ramps of PZT2); the second plot has averaged the traces. The PRMI data appears to be shifted upwards compared to the single-bounce data, by about 1V in the PZT2 output. We expect some drift and hysteresis in the PZT, but the single-bounce data was taken immediately after the PRMI lock, and a shift of this size is...surprising.
Using Kiwamu's expression from alog:14532, I calculate the PRC gain of the 45MHz sideband to be about 11.8 or 14, depending on which sideband peak you use. I think this is lower than we expect. The PRMI sideband lock was quite wobbly with a lot of angular motion, we might get a more robust measurement by locking the OMC to a particular mode and maximizing the transmission.
Here is a table of peak heights:
| Sideband Freq. | Single-bounce data | PRMI Data |
| -45 | 0.31 | 3.98 |
| -9 | 0.17 | 2.45 |
| 9 | 0.17 | 0.22 |
| 45 | 0.31 | 4.70 |
With a Schnupp asymmetry of 9.5cm the gain, for example for the upper 45MHz sideband, is (4.7/0.31) * (0.03*0.5*0.5) * (1/sin(2*pi*0.095*5*9100230/c)**2) = 13.9.
Just for a book-keeping purpose:
Two weeks later from this entry, we have measured the recycling of the carrier with the ASC loops fully engaged. We measured it to be 45 (see alog 15793).
The carrier recycling gain was measured to be 45 with the three ASC loops closed in PRMI.
Please forget the previous measured recycling gain (alog 15527).
(Some numbers)
Note that the IMC incident power was at 10 W during the measurement. REFL_LF dropped from a nominal of 83 mW to 6.3 mW when the PRMI was locked. The dark port ASAIR_A_LF stayed at 12000 counts during the lock. We could see a donuts mode at the dark port digital camera.
We shut off the ITMX CO2 laser at 20:00:40 in local time (4:00:40 UTC) for tomorrow's HWS project. We are leaving the PRMI locked on the carrier to see what happenes.
To avoid collision between the TCS step and Hugh’s sensor correction test, we have set the the senscor test to start 4.5 hours from now (through the magic of
sleep).Some notes on the PRMI recycling gain measurement (UTC date is 2014-12-23):
01:59:20 – MICH is locked on a dark fringe.
02:00:00 – IMC is unlocked.
Also, the last week’s improvements to the PRMI carrier locking (including ASC improvements) are now implemented in the
LSC_CONFIGSguardian.The lock held for about 8 hours, from about 8 PM to 4 AM local time.