nutsinee.kijbunchoo@LIGO.ORG - posted 13:00, Tuesday 14 July 2015 - last comment - 17:23, Tuesday 21 July 2015(19626)
Added SLEDS ON warning to SYS_DIAG
It should not be on during data taking.
It should not be on during data taking.
CO2X laser RTD sensor alarm (H1:TCS-ITMX_CO2_INTRLK_RTD_OR_IR_ALRM) tripped at 14 Jul 15 17:15:00 UTC this morning (10:15am), shutting off the CO2X laser. Folks were pulling cables near HAM4 this morning, which is probably why it tripped. CO2X laser was restarted at 19:30:00 UTC, and is now running normally again.
Just adding some words, parroting what Elli told me: this temperature sensor (RTD) is nominally supposed to be on "the" viewport (HAM4? Some BSC? The Injection port for the laser? Dunno). This sensor is not mounted on the viewport currently, it's mounted on "the" chassis, which (I believe) resides in the TCS remote racks by HAM4. She's seen this in the past: even looking at this sensor wrong (my words, not hers) while you're cabling / electronics-ing near HAM4, this sensor trips. As she says, this was noticed and recovered by her before it became an issue with the IFO because recovery went much slower than anticipated.
If I understand correctly the sensor I think your talking about then yes this should be on the viewport (the BSC viewport which the laser is injected in). The viewport sensor though is an IR sensor, but for some parts of the wiring in the control box (and thus on the MEDM screen) the IR sensor and RTD sensor are wired in together making it hard to know which one caused the trip. Its supposed to monitor scattered light coming off that viewport. It is very sensitive and can be affected by humans standing near it, light being shown onto it (one of the ways to set the trip level is to hold a lighter up to it ), maybe also heat from electronics, etc. So just sitting in the rack I am not at all surprised that it is tripping all the time and causing grief.
My suggestion is to try to get this installed on the viewport if you can, otherwise if you can’t and it really is causing problems all the time, there is a pot inside the control box which you can alter to change the level at which it trips.
After bringing the IMC down this morning, we had trouble getting the IMC back up. The alignment was bad enough after recovering the seismic and sus that the wfs would walk out of alignment. Keita recovered the alignment by ramping the WFS gain down (on IMC_WFS_MASTER screen (under the IOO dropdown), lower left, it's nominally .1) and moving MC1 and MC2 to maximize the power on MC2_TRANS_SUM and minimize IMC_REFL_DC_OUT, while watching them in dataviewer. He then tweaked MC2 to center MC2_TRANS P and Y to near 0 (~.001) on the PD (on the IMC_CUST_OVERVIEW, top right, on the little pd graphic right of MC2). The gain on the WFS was then ramped up to some small number (I think ~.004? maybe .04) and the IMC watched to make sure it didn't go unstable. When it looked stable, the gain on the WFS was ramped back up to .1.
We wasted a bunch of time trying to retrieve earlier alignments, clearing wfs histories and moving the PZT (a strange land where pitch is yaw and yaw is pitch), before Keita decided to just do the realignment by hand.
Note that the manual alignment was done after everything was brought back to old numbers (MC1, MC2, MC3 using witness BOSEMs, PZT offset using the output of the PZT before the maintenance). Even though the PZT change was not huge (as seen in the MC REFL position), I cannot claim that the change was nothing.
Also, at first I was confused by the fact that the MC trans camera looks as if the beam is split (01 mode) even though MC is locked to 00. Kiwamu told me that the only way to make sure is to look at IFO cameras like IFO REFL and AS.
PSL FSS oscillation precluding IMC locking
It appears that FSS oscillation was wreaking havoc with the ISS and this was the cause of the IMC not locking.
Reducing the FSS Common gain to zero then bringing it back up to 26 dB stopped the oscillation, as seen on the "PZT MON (FAST)" trend display on the PSL FSS screen.
It the display shows a black region (rail to rail oscillation), then the FSS is oscillating. In the nominal state, it should just show a think black horizontal line.
The FSS was tuned up this morning and is now operating as designed ~ 500 kHz UGF, 60 deg phase margin, no features (peaks) up to 5 MHz. However, it may not be as robust against kicks from the IMC as it uses the FSS as its frequency actuator.
We did not take time this mornining to investigate the stability of the FAST/Pockels Cell crossover. I was somewhat surprised to see the FAST gain at 5 dB. It may be that the crossover is not stable.
We used to run the FAST gain at 15 dB. Seems that it was turned down to 5 dB on April 15, 2015.
Next opportunity will check the crossover by looking at the mixer monitor noise spectrum in the 1-50 kHz frequency range as we adjust the fast gain - optimize the tradeoff between FAST gain and noise peaking at the crossover.
JimW is generating a request to TJ to add an alarm for the FSS range to the Guardian.
FSS oscillation was fixed while I was tweaking the MC2 trans position. Before that, IMC locked to the correct mode but the IMC WFS ran away.
So it seems like the alignment thing was a red herring.
The FSS went into oscillation again, after talking with RIck on the phone we turned the common gain down from 26dB to 23dB.
J. Oberling, R. Savage, J. Bartlett
Summary
We went into the PSL to tweak the beam alignment into the FSS RefCav and PMC. The FSS TPD was left at 1.67 V with a RefCav visibility of 85% and we found that the RFPD DC monitor on the FSS MEDM screen is not reading accurately; will have to fix this. We still are not sure what is causing the drift. Due to time constraints we did not touch the PMC, currently planning on doing that during the next maintenance period.
Details
Here is the FSS as we found it upon entering the PSL enclosure:
We performed the following steps to realign the beam into the RefCav:
At this point we wanted to measure the visibility of the cavity. We plugged a multimeter into the DC port of the RPD and noticed that the reading on the multimeter was different from the reading on the RFPD DC monitor on the FSS MEDM screen. Rick then used the multimeter to center the beam on the RPD; this was done while the loop was locked. There was no change in the TPD voltage. We then measured the RefCav visibility:
Finally, we set the UGF of the FSS loop. To maintain the UGF at 500 kHz we set the FSS common gain at 26dB. This gave a UGF of 500 kHz and a phase margin of 59°
After all was said and done the RefCav TPD had a final reading of 1.67 V. In the interest of time, we then left the PSL without adjusting the beam alignment into the PMC so Robert could begin his work with the IO periscope. We plan on returning to the PMC alignment next maintenance period.
Kyle, Gerardo 0850 - 0900 hrs. local -> In and out of Y-end Kyle, Gerardo Connected LD to exhaust of Y-mid turbo and sprayed helium on turbo fittings -> Found that this turbo has a "Leak valve" a.k.a. a solenoid vent valve which is either not connected or absent altogether on the site's other Main Turbo Pumps (MTPs) -> The turbo had been left levitated but not spinning since John W. and Gerardo's earlier investigation -> As such, this vent valve would be open -> Found that the clamp for the blank on this valve was loose -> Tightened -> With the turbo levitated but stopped, the QDP80 running but valved-out, safety valve and turbo bypass valve opened we sprayed the turbo's CFF and NW fittings with no obvious "smoking gun" -> It is likely that tightening the blank on the vent valve may have been the leak on the turbo side of the 10" gate valve For our next session we will vent the turbo volume and remove and replace the vent valve with a blank followed be a leak testing of the CFF joints on the Y-mid volume Also, set IP9 to Fixed 7000V -> This leaves only the X-mid still in Step Mode (currently 5000V)
Upon noticing the vent valve mounted on the Y-mid turbo, Gerardo and I examined the X-mid turbo and found that it's vent valve was not installed. Knowing that we would never use it and not ever noticing it on any of the other MTPs, I assumed that the Y-mid having one installed must be the exception. Since then, I have surveyed the MTPs at the Corner Station and found that they too have them installed, albeit blanked off like the MTP at the Y-mid. Thus, the X-mid MTP is the exception not the Y-mid MTP
These are the ones added last week that are not used as interlocks for the high voltage. I updated the parameter settings to read out in Torr and wrote them to nonvolatile memory. This was an online change that did not require a restart.
Was not running when I came in. Not yet sure why or when it stopped.
On the production server: Jul 11 16:59:38 h1conlog1-master conlog: ../conlog.cpp: 301: process_cac_messages: MySQL Exception: Error: Out of range value for column 'value' at row 1: Error code: 1264: SQLState: 22003: Exiting. On the test stand server: Jul 11 16:59:40 conlog-test-master conlogd: ../database.cpp: 828: insert_dbr_double_values_execute: Error executing m_p_insert_dbr_double_value_prep_stmt. Parameters: H1:OMC-READOUT_ERR_GAIN, 1436659172531946392, 0, -nan, 0, 0. Jul 11 16:59:40 conlog-test-master conlogd: ../conlog.cpp: 314: process_cac_messages: MySQL Exception: Error: Out of range value for column 'value' at row 1: Error code: 1264: SQLState: 22003: Exiting. So it would appear that H1:OMC-READOUT_ERR_GAIN got a value of -nan which the MySQL server could not store.
Summary: ESD (EY) Actuation Strength 'may' have changed by about 10% at it max from ER7.
The actuation strength of the ESD can be calculated by comparing the height of Pcal lines to ESD lines. We know the calibration of Pcal line and using the DARM_IN1 as an intermediate between ESD line and Pcal Line we can transfer this calibration to the ESD.
We have been using an assumption that the response function is same at close enough frequency (few Hz apart). This assumption is still under investigation and looks like it is not necessarily true to the level at which we want our calibration to be accurate.
However for this result we are only concerned with change in actuation strength from some initial configuration. We chose this initial configuration to be the start of ER7 and the result is attached below. In the plot below the first long set of data is the first half of ER7 and the a small chunk at the end of the plot is the lock stretch from the weekend. Using all four Pcal lines it shows the actuation strength has changed by about 5-10 % after ER7 (possibly a result of discharge). Note the actuation strength itself was changing with time during ER7.
Kiwamu, Sudarshan
ISS Outer Loop Servo Board (S1400214) was modified to include a zero at 100 Hz to obtain a better phase margin. This was done by replacing a resistor R74 from 0 Ohm to 154 Ohm (D1300439) and has been documneted in the E-traveler.
Initial test has been done after the modification and the board will be installed today during the maintenanace period. Further performance test will be done after the installation and with loop closed.
The second loop transfer function measurement was taken after the modifications were done. The plot and data is attached.
J. Kissel, E. Merilh, J. Warner Found the IFO held in the INCREASE POWER state (that's why we're only at 30 Mpc, bcause the global DARM control hadn't switched to ETMY's LVLN driver, so we're limited by ETMX's HV Driver's DAC noise), though the requested state is DC READOUT. It's been locked for the past 4 hours. Checked SDF for any new differences since last night: - Accepted a few changes on the ITMs and ETMs for Violin Mode Damping (described in LHO aLOG 19594) - Looks like we've been messing with DRIVEALIGN P2L and Y2L gains for the ETMX as well. (No associated aLOG, but I've accepted them anyway, since we're locked) I've not accepted these changes (and therefore will be lost with the front-end maintenance today), but if they're needed: In the safe.snap Currently H1:SUS-ETMX_L2_DRIVEALIGN_P2L_GAIN 1.1 1.0 H1:SUS-ETMX_L2_DRIVEALIGN_Y2L_GAIN 1.37 1.3 - Brough the ISC_LOCK to DOWN (this didn't break the lock) - Brought IMC to offline (this broke the IFO lock) - Brought HAMs 1-6 to OFFLINE (technically just "ready" for HAM1 HEPI) - Brought BSCs 1-5 to OFFLINE - Brought ETMs and TMSs to SAFE We're ready to begin the scheduled tasks -- see LHO aLOG 19600
Sheila, Jenne, Matt, Stefan, Evan
List of things done today:
We had a spectrum earlier in the night last night that had better low frequency sensitivity. One difference between this and later locks was the BS coil driver switching, the DARM offset could also have been different but I am not sure.
Jenne, Sheila, Evan
We locked at 10Watts with low noise, and redid the OMC excitations that Koji and I did in alog 17919. We plotted the OMC L excitation against a model with a peak to peak motion of 36 um, and the result seems consistent with a reflectivity of 160e-7 that we measured on Friday by exciting the ISI. This is slightly worse than what we measured in April.
We made these excitations with the same amplitudes and frequencies that we used in April, but some of the velocities seem to be smaller. Jenne is working on doing a more thourough comparision, but it seems that the scatter is better when we are exciting Yaw and Transverse, if a little worse for longitudnal.
We used a frequency of 0.2 Hz for all excitations.
| DOF | excitation amplitude (0.2Hz) | time | Ref |
| OMC L | 20000 | 4:39:30 | 10 |
| T | 20000 | 4:43:51-4:47:00 | 11 |
| V | 20000 | 4:47:30-4:49:20 | 12 |
| P | 2000 | 4:51:38-4:53:20 | 13 |
| Y | 200 | 4:54:00-4:56:20 | 14 |
| R | 2000 | 4:56:47-4:58:00 | 15 |
I'm concerned that the times from the April data for the Longitudinal excitation that Sheila is using aren't quite correct. This means that for the "L" traces we're integrating some "no excitation" time in with our "excitation" time, and using this muddled spectra as the measurement of the OMC scattering.
I have pulled the data from April, and adjusted the start time of each measurement to ensure that the excitation channel was fully on at the start (the [0][0] "time series" trace in DTT), and was still fully on for the last average (the [0][9] "time series" trace). Since I only had to adjust the "L" start time, I think this is the only one that is affected. With this adjustment, I see that the knee frequency goes down for L and T. It stays about the same for P, and is hard to tell (almost no scattering) for Y. The amplitude is a little bit higher for L and P, but not by a lot. Since the knee frequency is directly proportional to the velocity (eq. 4.16, Tobin's thesis), this seems to imply that even though we were actuating with the same amplitude and frequency, the true motion is slower now than in April. Is this because we are also pushing around the weight of the glass shroud? I'm not sure how the glass is mounted.
The times that I'm using are as follows:
| 16-17 April 2015 (t0 UTC) | 14 July 2015 (t0 UTC) | |
| No excitation | 23:33:39 | 04:49:57 |
| L excitation | 23:47:47 | 04:39:30 |
| T excitation | 23:59:00 | 04:43:56 |
| Y excitation | 00:31:00 | 04:55:00 |
| P excitation | 00:24:00 | 04:51:50 |
Another thing to add:
Since June 25 (right after shroud thing was done) and including the time this measurement was done, OMCR beam diverter has been open and nobody cared to close it.
Though it's not clear if this makes any difference, any comparison should be done with the diverter closed.
Regarding Jenne's comment above, "Is this because we are also pushing around the weight of the glass shroud? I'm not sure how the glass is mounted." - the black glass shroud is mounted to the OMC structure, not the suspended mass. After installation, the ISI was rebalanced and retested.
[Matt, Jenne, Evan, Sheila] There is an enormous peak in the DARM spectrum at 4735 Hz. Shown in the DTT printout below is the IOP channel for the OMC DC PD (H1:IOP-LSC0_MADC0_TP_CH12), from 1 kHz to 25 kHz, and this 4.7 kHz peak is dominating by about 2 orders of magnitude. We wonder if this is perhaps an acoustic internal mode of one of the test masses, although we are having trouble finding a listing of such modes. Does anyone know where we can find a listing of test mass acoustic modes? Or, alternatively, does anyone have any thoughts on what this mode might be?
Sort of unsatisfying (because they're not the real deal, or their incomplete) FEA results for the test mass body modes can be found here: http://www.ligo.caltech.edu/~coyne/AL/COC/AL_COC.htm (Only for a right cylinder) and here T1400738 (only shows the modes which are likely to be parametrically unstable). A quick glance through the above doesn't show anything at or near that frequency (including abs(16384 - FEA results)). I've yet to see FEA analysis of non-test-mass optics, but I've been told that Ed Daw and/or Norna/Calum's summer students on working on it. The best I've seen on that is the ancient 2004 document for the Beam Splitter, T040232 which is where we colloquialy get the frequency of the beam splitter's butterfly mode, which was done by eyeballing the current beam splitter's parameter location Figure 2. (But, the modeled dimensions are wrong, and the wording is confusing on whether the listed frequencies are from the model with flats or not.)
It appears to be a 10th order violin mode on EY.
It is damped with a 1 Hz wide butterworth (unity gain in the passband), a +100 dB filter, and a gain of -30. No rotation needed.
Jeff
As you notes there is some data in the links you already included and we have started to fill in the blanks. Refer to https://dcc.ligo.org/T1500376-v1. When we talk I (we) can complete.
Calum
For reference, with a combination of Slawek's (T1400738) and Calum's (T1500376) FEA models, and Calum's video of the test mass internal mode shapes (T1500376), we expect to find the drumhead mode around 8029 Hz, the x-polarized butterfly mode around 5821 Hz, and the +-polarized butterfly mode around 5935 Hz (using Slawek's values for the mode frequencies). The next two modes (at 8102 Hz and 8156 Hz) do not involve distortion of the test mass face in the direction of the beamline.
Nic, Sheila
We put an excitation into the HAM6 ISI ISO Y filter bank, (30000 counts at 0.3 Hz) from about 3:17-3:19 UTC July 11. We then did a by eye fit (on a log log scale)for a fringe wrapping model. We expected the excitation to result in 30 um motion of the OMC, but we had to use 36 um to get the fringe speed right. We get an amplitude reflectivity of 1.6e-7 for the single pass shelf. (compare to 1e-5 measured in 17919) We see no evidence of a second shelf or a shelf in the null stream.
We plan to make measurements in exactly the same was as 17919, if we get a chance again tonight.
There is a typo in this alog, the reflectivity is r=160e-7, as the legend in the plot says, not 1.6e-7 as I wrote.
The list below is for the time between now and O1. Since the sensitivity has reached the nominal goal set for O1, we plan to prioritize reliability and operations issues to maximize the up-time.
Under Reliability & Operations, I would also add:
11) Help to Train Operators
Also added warnings for when the cameras and the frame grabbers are on.
I've commented out the HWS and frame grabber on warnings because we want to use them during commissioning. We should uncomment this for the science run though.