no restarts reported.
conlog frequently changing channel report attached.
Nic ran Jim's script.
Earlier tonight, we had a large drift in ETMX pitch (1 urad over about 7 minutes). I turned off the sensor correction (ETMX ISI X only) for the last several hours, this seemed to help. Now I've turned it back on so we can see if this continues to happen overnight.
We are leaving the arms locked in green, and the mode cleaner locked. This should give a chance to see if the mode cleaner is really stable when there is no actuation on it.
Thanks Sheila, for reporting this.
I looked for minutes long features into the ISI CPS, at 0am and 4am, but did not find anything obvious over such low frequencies. However, I don't understand why the vertical Stage 1 CPS signal is so low. The local CPS signals should be quite larger if the platform was well isolated. I am getting inertial sensors and optical levers data to look into more details.
[Rich, Fabrice]
At 0am, the time series show a large drift in ETMX SUS top mass, not only in pitch but also in longidudinal, see first plot (the ylabel should say "nm"). According to the Stage 1 T240s (second plot), the ETMX ISI was performing as well as the other units, but this doesn't tell us anything about slow drift, so we need to get back to CPS data (maybe look at the rotations in the cartesian basis for the non-corrected CPS signals).
At 4am, ETMX SUS drift has stopped (third plot), though the sensor correction seems to be on (fourth plot).
K. Venkateswara
One thing to note is that turning sensor correction on is somewhat equivalent to blending at still lower frequencies than the normal 45 mHz. This makes it very sensitive to ambient ground tilt (caused by human activity or wind). It should not be used if there are people/activity near the ground seismometer.
Using tilt-subtraction makes sensor correction less susceptible to wind-induced tilt but unfortunately BRS is very sensitive to gravity gradients from people. So walking near the BRS when it is being used can cause very large low frequency signals to show up in the super-sensor.
Should we ask the operators to turn off the sensor correction at End X if they know someone is headed down there?
Did you and Evan go there around 6 PM? The attached plot shows a spike at ~6:20 PM
In general, yes, it would be better to turn off sensor correction along the horizontal directions during the day if there is a chance of someone being close to the ground seismometers.
Yes Sensor correction should not be on if there is any activity in the VEA.
Sensor correction is a form of feed forward so it assumes that the chamber and ground sensor are seeing the same thing. So someone walking by the ground sensor, making a large local disturbance can produce large motions in the platform
[Rich, Seb, Fabrice]
We are now looking into HEPI to see if it caused the drifts that was observed on the ETMX suspension. Sebastien is processing the data.
Please let us know if this is not anymore of interest because the cause of problem is now known (for instance related to John's comment on temmperature, or Nic's comment on suspension control).
A 1ºC temperature excursion was reported in alog 15212.
Sheila, Alexa, Dan, Nic, Evan
EX/EY:
Setting up sqrt(TRX+TRY):
Attempt at sqrt(TRX+TRY):
Guardian improvements:
Using the L1 screen as a template, I increased the number of matrix elements in the input matrix screen. I couldn't just copy the L1 screen for 2 reasons. First they don't use a ramping matrix but H1 does. Second, they have an additional signal coming into their input matrix.
Their extra signal is the so-called "TR_DARM" signal. One nasty time bomb is that their signal would need to be inserted in the matrix at position 36, in between the TR_CARM and TR_REFL9 signals, shifting those down. So this screen will change all around if that difference is incorporated from L1.
screenshot attached
Sheila, Nic, Evan
The refcav power has steadily declined over the last 10 days. Tonight it got so low that the modecleaner could not maintain lock for longer than a few minutes.
Sheila and Nic have realigned the pointing to the refcav in order to recover the power.
Sheila and Evan measured the FSS path AOM efficiency.
Power levels:
Before the AOM: 64mW
First pass through AOM: 52mW
Second pass: 38mW
First pass efficiency: 81%
Second pass efficiency: 73%
Total efficiency: 59%
here is a trend of the ref cav trans and PSL temperature, its not clear if temperature caused the problem.
This is sheila
SR3 oplev was realigned to the new SR3 angle.
We've found that this oplev had a clipping problem even before SR3 angle was changed. OPLEV SUM used to be about 30000 counts, and after we were done the SUM jumped up to about 66000 counts without changing the whitening setting. Doug thinks that this might be a bit too high a count, but ADC is not railing so we'll leave it as is.
Details:
SR3 oplev had two serious problems that are not related to SR3 angle.
After these were fixed, Doug aligned the launcher such that the return beam comes through the receiver viewport/pipe cleanly. Due to the beam angle shooting up from HAM5, in order to avoid clipping by the receiver viewport, bellows and the pipe, the beam was positioned much higher than the center of the pipe opening at the receiver box.
At this point, we recognized that the oplev sensor couldn't be moved high enough to receive the beam as the vertical stage doesn't have enough range. Actually the vertical stage has a huge range, but at least 3/4 of that range is wasted to be able to lower the sensor to the position where there is no possibility of receiving any beam with any SR3 alignment.
We removed the aluminum part on which the sensor is mounted, Doug made new holes, we remounted the sensor at a higher position (4th picture) and the translation stages were moved until the beam was roughly centered (5th picture), and we used the MEDM screen to fine tune.
A cell phone camera with selfie mode turned out to be quite useful to monitor the beam position when there's no light on the sensor, and that's what was used to take the 5th picture.
The whitening board is already on the lowest gain setting, so I think we cannot reduce the counts that way.
I have turned off the single whitening stage that was on previously (LHO#14756). This won't help if the optic makes large excusions in pitch/yaw and saturates the ADC, but we are so far above the ADC noise that I think whitening is not necessary here. (See first attachment. Blue is with whitening, red is without whitening.)
The SR3 pitch oplev damping loop appears to work fine with no modifications. (See second attachment. Blue is loop off, red is loop on.)
(Alexa, Nic, Sheila)
We measured the ALS COMM OLTF and found the UGF to be ~400 Hz, with a crossover at ~70 Hz. In September we had changed filters in MC2, and CARM as reported in alog 14214 to increase the crossover frequency. I also noticed we had changed our configuration in the LSC_REFL_SERVO CM board relative to what was in model (alog 11109). Now we have:
9:17 Fil to pick stuff up at EX, then to EY PEM cabling
9:56 Doug to LVEA for SR3 OpLev work
9:58 Jeff and Andres to LVEA staging for SUS storage
10:22 Jeff and Andres exit LVEA
10:28 Krishna and Jim to EX for BRS checkup
11:03 Mitch and Jeremy out of LVEA
11:11 Cris to EX
12:02 Sheila and Nic to ISC electronics racks in LVEA
12:04 Fil back from EY
12:32 Doug out of LVEA
15:45 Doug to SR3 for more OpLev work
There has been some concern that there might be excess cps noise in some of the channels. So i looked at 20 minutes of data at 1am sunday night/monday morning.
Looking only above 30Hz where the sensors have hit the noise floor, all of the coarse channels are similar and between 3.5-4.5E-10m/rrtHz about what we expect.
The stage 2 channels show two outliers, ITMX H2 and ITMX V1, maybe BS H2 also but that is close enough so that it could just be at a large offset (we expect the noise floor to go as the gap squared) I'll check that.
The first thing to do is for me to look at another time, and to check the cables and connections for those sensors
I looked at a second data set calling it "B" (24 hours later) ST2 ITMX H2 and ST2 ITMX V1 still show excess noise BS H2 is down to 4.5-5E-10m/rtHz which is a little bit noisy, but probably within what we are calling acceptable. I attached the data because Jeff asked to see the ADC noise on the plot
When I say large offset I mean > 10000 counts, so 1200 counts is centered for this discussion
ITMX Stage2 H2 & V1 CPS offsets are 900 & 3800 counts. While V1 is actually the largest offset of all the BSC CPSs, H2 is 21st of 30 (towards the bottom) of Stage2 CPS offsets. At 1200cts, BSC2 H2 ranks 17th of 30. So the offset maybe an issue for ITMX V1 but the others...? And, what about ITMY V1 at 3700 counts and ITMX V3 at 3200?
Attached are all the BSC medms showing the offsets.
Some additional info regarding the CPS - On the figures are plotted time series, integrated RMS, and ASD down to low frequencies. Somme comments:
- At high frequencies, not much to add on sensor noise (ITMX and BS both have two CPS untis with elvevated sensor noise on Stage 2). I looked at data of the Nov 17th, 18th and 19th, and get similar results.
- All Stage 1 CPS units are within 1um p2p, except BS horizontal that is moving 4 times more. Something to look into.
- At the microseism, the three vertical sensors are moving in sync, on all stages of all platforms. Probably normal (the platform is inertially decoupled down to the micro-seism with th 90 mHz blends)
- The low frequency motion amplification is about 100 times larger in the vertical directions than it is in the horizontal directions.
The 5 figures in the previous log are for data ten on the 17th at 3pm PT.
Results and comments are similar for the 18th and 19th, except for ETMX (attached plot) that shows different behavior at low frequencies, as expected with the sensor correction that was turned on Tuesday. It also shows features on Stage 2 at the SUS resonances, that might need to be doubled checks.
Could this be related to the trips on ITMX? (alog 15021)
this log seems to have gotten hijacked
I check the HAM-CPS and they all seem to be good at high frequency
(Alexa, Evan, Sheila)
We roughly centered the EX IR QPDs; the beam is now on all four quadrants, however, more fine tuning could be done. The beam was slightly off in yaw common to both QPDs, and already fairly well aligned in pitch. I adjusted picomotor M14 by ~200 steps in yaw to bring the beam center on the QPDs. I did not have to adjust M4, which would affect the IR transmitted beam onto ISCTEX, and potentially clip the green beam. The current picomotor positions are:
M14: X = 53045, Y = -38603, M4: X = 9267, Y = 1665
The sum show about 1000 cnts on QPDA, and 700 cnts on QPDB. This is consistent with the power budget (alog 10006), so I believe this is the real beam and it is now centered enough.
I did something similar for EY. QPDA was farily well centered, with the beam on all four quadrants. QPDB was off a bit; so I adjusted M14 in both pitch and yaw, to get this beam better centered and on all four quadrants. This adjustment did not move QPDA all that much. There does not seem to be a picomotor position readback for EY ???? They are all zero. The sum show about 840 cnts on QPDA, and 760 cnts on QPDB.
J. Warner, K. Venkateswara
Jim installed Rich's SC filters to all sensor correction filter banks. This afternoon, I turned on ETMX SC to Stage 1 using the tilt-subtracted ground sensor and then for ITMX using the normal ground sensor (STS) along X. For Z, SC to HEPI was enabled for both chambers. Sheila then aligned the arms and locked them using ALS.
The aim was to observe if SC reduced arm motion between~ 50 to 500 mHz as indicated by the local sensors while keeping the low frequency motion small. The noise in this band seemed lower, but unfortunately activity at ITMX increased ground motion as measured by the seismometers which ended up re-injecting excessive noise at low frequencies. This test should be repeated later in the evening or night when activity at the corner is reduced.
For the moment, I have left tilt-subtracted SC on at ETMX and SC off at ITMX.
As per Aidan, I set all 4 of the LOWER RH RTD channel calibration gains and offste to their nominal setting. Likely these were not input after the summer vent or they were over written sometime since. Settings for all 4 should be:
LOWERRTD_GAIN = 50 (K/V)
LOWERRTD_OFFSET = -257 (C)
One arm RH calibration medm screen shot is attached.
However, a trend of the last hour of all 4 RH RTD channels since I made the setting change, show that there are likely missing external parts to 3 of the 4 temperature probes. Only ITMy RTD looks reasonable.
