Earlier today or yesterday, Sheila added some new "shuttered" states to the ALS guardians.  The ISC_LOCK guardian requests these states during the "bounce violin mode damping" state.  The new ALS states are just empty, so that we can have a final nominal state, so we know when we've completed everything.  This prevents the ALS guardians from reporting things like "lockloss" or "fault" when the green lasers are shuttered.  The new states only have a guardian edge coming from the "IR found" state. 

However, in the ISC_LOCK we were requesting these states, and then immediately closing the green shutters. If the ALS guardians detect that there is no green light in the arms before they've been told to go to this new state, they'll end up in "lockloss" or "fault".  I don't totally understand why, but if they are then told to go to the "shuttered" state from somewhere other than "IR found" , this causes a lockloss of the full IFO. 

Anyhow, for now I've put a 2 second sleep between the node requests and the closing of the green shutters.  At least one time we have now successfully made it through this state after my fix.  I will consult with Sheila and Jamie tomorrow about the best way to handle this - should we build in more explicit ways for the guardian to get to the "shuttered" state?

As a side note, we had several locklosses earlier in the day at this state, and I was unable to find any obvious reason for the lockloss.  Since these new states were already in use, I suspect that this problem is what caused those locklosses.

J. Kissel, D. Tuyenbayev, S. Karki, S. Kandhasamy

We've used the new infrastructure for the ESD / L3 / TST actuation strength tracking line for ETMY, turning on the line with a frequency of 35.9 [Hz] and amplitude of 0.08 [L3 LOCK ct]. We've tuned the excitation amplitude to be roughly half the amplitude of the 37.3 DARM and 36.7 PCAL lines, see attached ASD of DELTAL_CTRL for starters, and we'll iterate a bit once we get back to a better low-noise state (we're currently having a lot of trouble damping violin modes).

Since we were working on violin mode damping anyway (aLog 20280), we also tried some ETMX violin damping tuning.  At some point, we tripped the ETMX analog PUM current RMS watchdog.  We tried setting the H1:SUS-ETMX_BIO_L2_RMSRESET to zero, then back to one (which worked to reset the ETMY watchdog, when we tripped that once or twice).  We tried this reset procedure several times, but the watchdog isn't resetting. I don't know enough about this system to diagnose it further, so I await guidance from someone more knowledgeable in the morning.  Our low frequency noise is kind of terrible, which might be because it looks like we aren't driving the ETMX L2 stage at all, but we are able to get to the Nominal Low Noise state (the trip happened at the DC Readout state).

Attached is a screenshot of the current state of the ETMX suspension screen, including the tripped L2 RMS watchdog.

J. Kissel

I've updated several QUAD screens, including the overview, to reflect the changes that were made yesterday. In the process, I've also added some stuff to the overview screen that was previously only shown on sub-sub screens such that problems are better exposed from the top level. I attach screenshots, but the changes include:
SUS_CUST_QUAD_OVERVIEW.adl --
- Adding a link to a new screen for the new ESD / L3 / TST calibration line.
- Cleaned up the LHO-only, UIM tidal path, better showing how it's added into the UIM control signal.
- Brought the HV ESD driver ON/OFF switch to the overview, and renamed it from the misleading "RESET" to "ON/OFF."
- Brought all relevant voltage (for the ESD) and current (for the OSEMs / coils) up to the top near the output.
- Added a red light surrounding the COILOUTF block that appears if all of the OSEM sensor signals are zero (literally an AND of all four, checking whether the INMONs are < 5 cts).

SUS_CUST_QUAD_BIO.adl --
- Changed the HV ESD driver name from the misleading "RESET" to "ON/OFF."

SUS_CUST_QUAD_L3_ESD_LIN_WITH_CHARGE.adl --
- Added a whole bunch of text and polygons all over the screen to better indicated what "linearization bypass ON vs. OFF" means, since this switch confuses everyone.

SUS_CUST_QUAD_MONITOR_OVERVIEW.adl
- Removed now defunct EPICs records and level indicator bars for the DIGITAL readbacks of the ESD HV driver, which are now just binary bits.


All changes have been commited to the userapps repo. To inherent at LLO, just svn update
/opt/rtcds/userapps/release/sus/common/medm/quad/
the directory.

Related alogs: 17610, 19720

Jenne, Stefan

We had highly rung up violing modes tonight, in particular 508.289Hz was outrageous.
Nominally it should be on ETMY. We pushed on that optic in pitch, yaw, length, and with all sorts of different filters (narrow ones, broad ones, different feed-back phases, etc.)
We succeeded in ringing up all three neighbouring modes, and thendam them again. But 508.289 never changed its size. We even tried pushing ETMX (its modes are closest to ETMY), but no success...

(There was a typo in the frequency in the first version, hence Evans comment)

Current state of ASC sensing and actuation.

[Note: The INP2 loops are not used during lock.]

Charge measurements done on both ETMs. Measurements results are in attachments. The same trend remains (discussed in 20067)

Patrick, Carlos

We disabled and stopped the following services on h1ecatx1:

Acrobat Reader Updater
Windows Update
Windows Search
Windows Defender

Pcal Team,

Calibration:

We calibrated the Photon calibrator readback photodiodes at EndX and the new displacement calibration factors for TxPD and RxPD compared to the last calibration are reported below. The difference in the calibration factors are within our reported uncertainty. These number are also uploaded to DCC document T1500252.  A detail report of the calibration factors, optical efficiency and other intermediate calculations is attached to this alog. 

Other Details:

Beam Clipping:

We had a beam clipping issue at ENDX  (alog #19899) and  fixed it after aligning the beam using the steering mirror on transmitter module last week.  (alog #20054). We checked if this alignment was still good by measuring the power at the transmitter side and the receiver side and alignment seems to be good. In addition, we also measured the output power of the laser before the AOM. The measured value (1.6 W) was consistent with what we measured last time on 04/10/2015. 

AA Chassis:

PCAL AA chassis had 3 channels which were either railing or dead and this issue has been reported in a  separate alog (LHO alog #20259) and a fix is underway.

BNC-DB9 Chassis:

We had installed a DB9-BNC chassis to route the working standard signal (for calibration) and AOM drive signal (monitoring) to the AA chassis few weeks ago. These chassis were not tested after installation so we used a calibrated voltage source to test the chassis before proceeding with the calibration. 1 V of calibrated source gave us  ~1637 cts on our readback channel.

OFS Transfer Function:

As a part of calibration we also measured the transfer function of the Optical Follower Servo and a plot is attached. OFS has a unity gain of 100 KHz with  a phase margin of about  62 degrees.

Hannah, Stefan, Daniel

It was determined that the broadband noise we've been seeing has been caused by the Harmonic Generator (SN 1043-03, DCC S1000798). To see if this was an issue with the unit or if this is the normal operation, we tested the spare. Using an RF frequency of 9 kHz, lowpass filter of 10.7 kHz, we tested all seven outputs and measured the following noise:

The x5 output is what we're interested in, and the noise seems to be about the same as what we're already seeing. The power supply was also checked to make sure there were no stray signals. 

The ETMX ESD got stuck again, with both the bias and all quadrants at a constant negative value.  Jeff B and I drove down the the end station to reset the driver by toggling the red button on the driver box.  Jeff has a picture of this and will add a note to the operator troubleshooting wiki about this problem.  

This has been happening more since we installed the low noise driver (which was probably an unnecessary change for EX where we do not plan to use it). 

ALL TIMES POSTED IN UTC

15:00 IFO locked at DC_Readout

15:45 Jeff B. (H1 op) proceeded from DC-Readout. IFO broke lock. Trying to recover.

16:31 Fil and Peter taking an RF multiplier to Mid Y

16:59 Fil and Peter back from Mid Y

17:00 Fil into CER to look for a power cable for the RF multiplier. None at the MY station.

17:20 Peter into Optics Lab

17:40: Ellie headed to HWS table in LVEA

17:50 Eliie out

19:53 Tour Group into control room

20:09 Sudarshan and Fil out to EX to power cycle Pcal AA chassis. No VEA entry.

20:50 Sudarshan and Fil back from EX

21:28 Kyle, John, Robert out yo Y-2-8

21:41 Jeff B and Sheila to End X

21:55 Kyle and company back from Y arm

21:55 Sheila and Jeff out of X End

Using the calibrated DRMI channels created and described by Kiwamu in entry 18742, I grabbed data from the lock of August 3, 2015, starting at 04:20:00 UTC. The attached 4 page PDF shows spectra of the open loop and residual displacement noise for SRCL, MICH and PRCL. The 4th page shows the coherence of SRCL with the other 2 degrees of freedom.

The SRCL spectra has a curious shape: it comes down quickly with frequency to 10 Hz, then is fairly flat from 10 Hz to 50 Hz, then falls by a factor of 5 or so to the (presumed) shot noise level that is reached above 100 Hz. What is this noise shelf between 10 Hz and 80 Hz? That is exactly the region where the SRCL noise coupling to DARM is troublesome. Our usual approach is to send a SRCL correction path to DARM to reduce the coupling, but this spectrum shows that there should also be some gain to be had by reducing this noise shelf.

The last page of the PDF shows the coherence between SRCL and MICH & PRCL, and it indicates that the SRCL noise shelf could be coupling from PRCL noise -- the coherence is fairly high in this band, though not unity. This suggests that the DRMI signals could use some of the demodulator phase and input matrix tuning that Rana has recently done on L1, reported in LLO log entry 19540.

To complete this log entry, it would be useful if someone at LHO could add the open loop transfer functions for each loop (models), and other pertinent info such as DC photocurrents for these detectors and the input matrix coefficients.

Jenne noticed in alog 20099 that PR3 jumps on lock-lass when the integrators are cleared, but then comes back with a 4min time constant to more or less the same location.

Thus I implemented a split integrator for PR3 PIT:
FM1 z4min:p0  zpk([6.6315e-04],[0],6.6315e-4,"n")
FM2 :p4min    zpk([],[6.6315e-4],1507.955,"n")

Instead of clearing the filter module, the down script now simply turns off FM1 and turns it back on, producing a 4min exponential decay.

The guardian is updated to use this (set the right filters, use new clearing procedure in DOWN state).
Additionally I took out take out any clearing in LOCK_DRMI_1f. (PR3 is no used in DRMI ASC, so there should not be anything to clear anyway.)

[Sheila, Jenne]

We have had a violin mode at ~ 508.29 Hz rung up for the last several days.

Part of the problem was that the ETMY Mode7 filter was railing at its limiter.  This filter bank has the new "flat phase" filter that is being tried, for damping many modes at once.  Evan ramped the gain to zero for this filter bank.  After ~30 minutes we didn't see any noticeable change in the height of the peak.

The only other filter bank that was enabled was the Mode5 bank, with a 506-513 band pass.  We turned off the "-60deg" FM2.  After an hour and a half or so, we see the height of the violin mode has been reduced by almost a factor of 10.  We'll check back on it tomorrow.

Also, there is a new violin mode blrms screen, accessible from the quad overview screen.

Rana pointed out to me that the PR3 and SR3 suspensions may still have some shift due to wire heating during locks (which we won't see until a lockloss, since we control the angles of mirrors during lock).

Attached are the oplev signals for PR3 and SR3 at the end of a few different lock stretches, labeled by the time of the end of the lock. The lock ending 3 Aug was 14+ hours.  The lock ending 31 July was 10+ hours.  The lock ending 23 July was 5+ hours.  The lock ending 20 July was 6+ hours.

The PR3 shift is more significant than the SR3 shift, but that shouldn't be too surprising, since there is more power in the PRC than the SRC so there is going to be more scattered light around PR3. Also, PR3 has some ASC feedback to keep the pointing.  SR3 does not have ASC feedback, but it does have a DC-coupled optical lever.  SR3 shifts usually a few tenths of a microradian, but PR3 is often one or more microradians.  Interestingly, the PR3 shift is larger for medium length locks (1 or 1.5 urad) than for very long locks (0.3 urad).  I'm not at all sure why this is.

This is not the end of the world for us right now, since we won't be increasing the laser power for O1, however we expect that this drift will increase as we increase the laser power, so we may need to consider adding even more baffling to the recycling cavity folding mirrors during some future vent.

[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?