Attached are screenshots for the past 7 days of optical lever trends for PIT, YAW, and SUM.
This completes FAMIS request 4683.
Peter was in the PSL enclosure and looking at the FSS - his alog will give details.
He's done so I'm starting to lock.
DRMI locked at 16:36UTC
POP X PZT railed, but POP signal is still centered on the QPD, so this is on the "to be fixed" list, but does not prevent locking. POP X is accessable from the ASC overview screen.
in DC READOUT TRANSITION, OMC guardian was stuck in DOWN, and was unstuck by running it through INIT.
I unintentionally killed the lock by requesting the INCREASE POWER state in ISC_LOCK.
I thought this would just stop the ISC_LOCK guardian in this state, keeping the input power at 38W.
Instead it reran the code for INCREASE POWER from the beginning and lowered the input power to 10W, killing the lock.
Broken:
So I thought the power was going to increase to 50W, based on what the LASER_POWER guardian main screen was showing, however TJ explained that the guardian can only request so many states, so the power was going to stop at 40W but the guardian could not show that because 40W was not a requestable state.
Fixed:
TJ rewrote the LASER_POWER guardian to make 40W a requestable state, so when we're going to 40W it will show this.
TJ also set the ISC_LOCK to stop at 25W input power on out next lock.
Currently, we have the IMC locked and at 40W input power.
Keita is looking at the ISS Second Loop and measuring the correct offset for 40W.
18:32UTC - adjustments made for running at 25W are complete - now relocking H1
DRMI locked at 18:43UTC
19:12UTC - H1 in DC readout and heading to ENGAGE ISS 2nd loop
19:58UTC -------------
H1 made it to ENGAGE ISS 2ND LOOP which is good, because getting to the point where we could engage the 2nd loop is progress, however engaging the loop revealed an issue which broke the lock.
Jenne and Keita are looking into it.
******** my estimate of having H1 in Observer was a bit optomistic - 4PM today (23:00UTC) is more likely.
21:04UTC - locked and going to ENGAGE_ISS2ND_LOOP without engaging the loop, to do measurements
lockloss
last entry for this log:
21:52UTC - H1 is back in ENGAGE ISS 2ND LOOP with the ISS 2nd loop disabled.
Keita and Jenne are looking for a fix, so H1 can go to Observe.
Attached is a plot of the diffracted power versus offset slider position. With the current slider setting of 6.35, we are diffracting around 3 W of light. Even if the output power of the laser was only 100 W, this would be 3% not the indicated ~15%. However we know the output power of the laser is greater than 100 W, so obviously the percent diffracted light is even less than 3%. This is noticeably less than when the ISS was last tuned up. Back then a slider setting of 6.35 would diffract about 7 W. Although nothing has changed hardware-wise, it is possible that the 80 MHz source for the ISS AOM is no longer providing the ~32 dBm, or the AOM driver is deteriorating. Jason/Peter
With the pre-modecleaner unlocked the output of the locking photodiode was between -1.070 V and -1.080 v. Locked was between -170 mV and -185 mV. This gives the pre-modecleaner visibility to be between 83% and 84%. Jason/Peter
Attached are measurements of the ISS transfer function performed after a
minor alignment adjustment to the ISS AOM. These were taken with the gain
slider at 6 dB and 9 dB. The offset slider was left at 6.35.
With the gain slider at 6dB the UGF is about 54 kHz; 9 dB 70 kHz.
However there is considerable peaking in the noise spectrum. The free-running
noise is also attached.
All measurements were taken with PDA which was the in-the-loop sensor
at the time. The reference signal was at -2.00. At this setting the measured
DC output of PDA was -8.70 V.
Jason/Peter
After tweaking the alignment into the pre-modecleaner, the DC output of PDA was measured to be between -12.5 V and -12.7 V with the ISS off. The half waveplate in the ISS PD box was adjusted to bring this down to about -9 V unlocked.
Attached are the transfer function measurements of the FSS taken yesterday afternoon.
The first two plots are taken with the common gain at 16 dB and fast gain of 22 dB.
The second measurement (C16F22-2) I think was affected by the modecleaner trying to
acquire lock, which might explain the notch-like feature just past 200 kHz. The
UGF in both measurements is about 195 kHz.
The third measurement, taken with a common gain of 20 dB and a fast gain of
22 dB is, I suspect, also affected by the modecleaner trying to acquire lock.
Jason/Peter
This is as far as I have been able to get the IFO tonight. I tried to set the intent bit, but it will not engage. I have set the Ops Observatory Mode to Observing.
The 'Observing' button (intent) will only engage if the interferometer is 'ready' (bit 2 of ODC-MASTER). In practice this means you can only press the button when the IFO node (top-node) is in full OK mode (current state == request == nominal). I think this requires all other guardian nodes to be nominal, no SDF changes, etc, etc.
This can be disabled (so you can press the button anyway) by setting H1:ODC-AUTO_UNSET_OBS_INTENT to 0, but downstream users (data analysis/detchar) won't be notified anyway because they look at the 'ready' bit as well to see when to analyse.
Ross and I are the only ones in the control room. The last lock was lost at ENGAGE_ISS_2ND_LOOP from a pringle mode on ETMY.
Carl is here as well. We just lost lock in ENGAGE_ISS_2ND_LOOP again.
Per Sheila's suggestion, went to ADJUST_POWER after COIL_DRIVERS. Set to 25 W and then went to ENGAGE_ISS_2ND_LOOP. Lost lock again in ENGAGE_ISS_2ND_LOOP.
Tried skipping from COIL_DRIVERS to LOWNOISE_ESD_ETMY. After a while in LOWNOISE_ESD_ETMY, it seemed to be stuck, so I requested NOMINAL_LOW_NOISE. It still didn't move on, so I re-requested LOWNOISE_ESD_ETMY. This broke the lock.
[Everyone]
We have determined (a few hours ago) that flipping the ESD bias sign on ETMX does not allow us to lock ALS DIFF. Jeff has looked through the settings, and everything is flipped to match the bias sign as appropriate, but we're still not able to lock. It looks like a crossover is unstable, or something like that. For now, we have reverted the ETMX ESD bias to its pre-Tuesday state, which has facilitated locking. Team SUS will look into this later.
The ISS is much better behaved now that the alignment work was done. However the FSS gain change was making the IMC loop very nearly unstable, and we lost lock during the power-up twice due to this instability. Sheila and Keita will post their measurements that discovered and fixed this issue.
We have so far been able to power up to 40W once, but it looks like a PI rang up pretty quickly. Carl will post details, but this is a new mode that hasn't been a problem previously, so it does not yet have damping settings.
At this time, it looks like there is no problem in getting to 40W, and other than PI damping we should be able to get all the way to low noise.
If Carl is unable to find damping settings relatively quickly, we may choose to instead only go to 20W for tonight, so that we can get to low noise and set the intent bit. Stay tuned for more updates...
Locklosses around 0230 and 0345 were associated with the 18040Hz instability first two images. In other locks this mode's amplitude did not reach these elevated levels. The lock ending at 0800 appears to have just scraped through the transient, in the last image the mode amplitude can be seen to grow, then saturate the sensing (I assume), before damping.
Jenne, Sheila, Keita, Peter and Jason are here. The work in the PSL enclosure has completed for now. The IFO has made it to DC readout twice, but lost lock on increase power. Keita and Sheila are taking measurements related to the FSS.
The first attachment is an IMC OLG measured with the FSS common gain at 16dB, with something unstable at around 200 kHz. The second attachment is with a common gain at 20dB, which gives us about 4dB of gain margin at 200kHz. We have left the FSS like this and the IFO was able to power up to 40 Watts. Data attached is for the state we are leaving it in, FSS fast gain 22dB, common gain 20 dB, IMC in1 gain 16 dB at 2 Watts.
If the operators have trouble getting the FSS to relock after a lockloss they can try reducing the common gain, and then setting it back to 20dB once it is locked.
Dan, Jim, Dave:
we tried several things today to try to make h1fw0 more stable. These are:
reintroduction of h1ldasgw2 to take NDS traffic away from h1ldasgw0 (leaving it only used by h1fw0)
upgrade the network link between h1fw0 and h1ldasgw0 from a cat5e 1GE to a fiber opitcs 10GE using borrowed intel 10GE cards from LDAS
reconfigure fw0 to not write commissioning frames
power cycle fw0 and ldasgw0
these changes have not made fw0 any more stable. fw1 continues to be more stable, some of its restarts were coincident with fw0 restarts (within several minutes)
in a final attempt to make h1fw0 stable for tonight I have reduced its configuration to only save science frames (is not writing commissioning, second trends or minute trend frame files). Since that time fw0 has been stable (2 hours) with fw1 restarting once. The issue certainly appears to be file system access, we will continue our investigation tomorrow.
Note that on the DAQ overview MEDM screen, only the science frame size should match, CRC and Commissioning size numbers will not match.
Took advantage of laser being down (aLOG #28142 & 28145) to change the water filters in the chiller room. Swapped out the Diode Chiller filter. The filter looked fine, but changed it out anyway to see if this had any effect on the rising PSL chiller pressures. Did not change the Chrystal Chiller filter. The filter bracket is poorly mounted to the wall and is coming loose. Need to secure the filter bracket to the wall before unscrewing the filter canister.
48 hours after changing the Diode filter the PSL chiller pressures and flows seem to be flattening out. Will continue to monitor over the next several days. The plan is to swap out the Crystal chiller filter in conjunction with remounting the filter housing.
J. Kissel, E. Goetz Having a few new breakthrough ideas on the UIM actuation system (see LHO aLOG 24914), we explored whether we are modeling the [m/N] L1/UIM force to L3/TST displacement transfer function incorrectly. This was done by driving the UIM out to 600 [Hz] and measuring the response in DARM. Not only did we find the expected-but-not-yet-modeled wire violin modes at ~330 [Hz], 420 [Hz], and some at ~500 [Hz], but we found several bending-mode resonances at 111 [Hz] and 166 [Hz]. Indeed, upon first glance, we think the 111 [Hz] resonance is the remaining missing frequency dependence that explains the turn-up seen at 100 [Hz] in all previous measurements of the UIM to TST transfer function. We'll process in more detail some time in the future, but check out the attached screen shots and be amazed at how not 1/f^6 the L1 to L3 transfer function is. -------- We'd started by exciting the L1 stage via awggui in a broad-band fashion such that we could catch all of the wire violin mode frequencies watching DARM. As Evan mentions, we had suspected that these wire resonances -- documented in T1300876 -- were the source of the deviation from 1/f^6, and they'd just not been included in the SUS dynamical model -- [[EDIT -- Brett has now included them in the model, and they are a non-negligible effect; see LHO aLOG 24915]]. This broadband TF is shown in the first attachment. Black is the with excitation ON, and red is ambient (to distinguish the ~505 [Hz] fiber violin modes from the ~495 [Hz] TOP to UIM wire violin modes, and the Beam Splitter violin modes & 331.7 [Hz] calibration line from the Sus. Point to TOP wire violin modes). Only the peaks of the wire violin mode resonances are visible above the DARM noise; driving them any higher breaks the IFO's lock. Just in case, we drove down to the same ~80 [Hz] region, and BINGO! We also found new, unexpected resonances at 166 [Hz] and even as low as 111 [Hz]! (see second and third attachments) Our best guess for the source of these resonances are imperfect actuators. Perhaps the bending of the L-bracket that mounts the OSEM coil to the reaction chain's UIM (see D060375, see page 1 for the total assembly, lock at pg 14 for the L-bracket). Though, if it were these L brackets, I'd suspect there would be 4 independent resonances... also it doesn't look like enough moving mass to have resonance frequencies as low as ~100 [Hz]... dunno, will think more. Finding something at 111 [Hz], we then took a careful swept sign measurement covering it, and indeed, it looks strikingly like another piece of the UIM puzzle. (see 4th attachment). We also grabbed a PCAL to DARM transfer function over this frequency vector, so we can turn the TF into an absolute calibration later. For future reference, the templates for the swpet sine TFs are here: /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PostO1/H1/Measurements/FullIFOActuatorTFs/ 2016-01-12_L1toDARM_FullLock.xml 2016-01-12_PCALYtoDARM_FullLock.xml and I attach screenshots of the awggui sessions used to excite L1 and PCAL in a broad-band fashion (DARM_IN1 ASDs during the broad-band excitations were taken using the standard wall FOM for DARM).
Weird about the 111 Hz and 160 Hz modes. If it is a mechanical mode of the UIM OSEMs, it is probably more likely to be the magnet-flag assembly, which makes a nice long cantilever, and is attached to the main chain itself. See page page 16 of D060375. Additionally, if for some reason the set screw holding the flag assembly in place is loose, you met get lower frequency modes.
The L bracket is on the reaction chain, so if the mode was in that it have to couple through to the main chain via the magnetic field gradient inside the coil; it's possible but one more step removed.
You could try exciting these modes one OSEM at a time, to see if it is coming from one in particular. If we get lucky, maybe we'll find there is a simple fix, like tightening a set screw.
I also wonder if these features exist on other test mass suspensions.
The 111Hz feature is very likely from the first internal mode of the UIM blades which is not surprising sicne it will ebt there at some level due to cross-coupling. The frequency is very close - see for example https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=16740 where the frequencies were measured at LLO for their quads to be in the range ~111 to 112 Hz. As for the 166 Hz, I don't have a good idea. It is not the second resonance of these blades. Lab measurements of such a blade here at Caltech give the second mode at around 325 Hz. Funnily enough this is ~twice the observed feature, but I can't think why we would see something at half the frequency of a blade mode.
I was asked by Jeff to fit the UIM data so that we can include the peaks at 111 and 167 Hz in our calibration model. After some struggle, I ended up doing an emperical zpk model which gave me the following parameters:
=========================
gain = 2.270401e-09
f:pole0 = 1.113398e+02
Q:pole0 = 5.596904e+14
f:pole1 = 1.950899e+02
Q:pole2 = 4.743158e+00
f:zero0 = -1.133450e+02
Q:zero0 = 6.220362e+01
=========================
In addition to these fitted parameters, I had fixed zpks which are 6 poles at 1 Hz and 1 complex pole at 166.7 Hz with a Q of 200. The attached shows a comparison of the fitting and data. I have used fminsearch to minimize a weighted residual. I didn't have an energy to compute the uncertainties in the estimated parameters.
One thing I don't like with this fitting is that the fitted model falls faster than the nominal 1/f^6 slope above approximately 160 Hz due to the extra poles that I put in to make the fitting better at frequencies below.
The code and resultant figure can be found at:
