Over the past hour or two, locklosses (8) have all occured during transitions to ANALOG_CARM, DARM_OFFSET, or ENGAGE_SRC_ASC. Microseism and wind have been quiet. Leaving it in DOWN. 

I've turned the ETMX ring heater back on (requested power 0.5W top and bottom). 

Ross, Tega, Evan, Terra

Tonight we successfully damped a known parametric instability at 15540.6 Hz with the newly implemented ESD damping scheme. 

In April last year, this mode was detected in the X-arm during a 15W lock. Ultimately it was avoided by turning on the ETMX ring heater (0.5 W requested power top and bottom), shifting the optical mode peak down in frequency and away from ~15540 Hz mechanical modes. To test the new active damping scheme, we turned off the ETMX ring heater, allowed 15540.6 Hz to start to ring up during a 24W lock, and damped it by driving the UR and LL quadrants of the ETMX ESD.  

Below we tracked the amplitude of the ~15540.6 Hz mode. Leftmost action is the important part: first we briefly manually rang it up (gain -1000) before switching the gain sign (gain +500) to rapidly damp. Attached images show power spectrum before damping and immediately after.  We had planned to ring up and down again to get a better idea of the gain settings, but with the newly low magnitude peak, the line tracker got confused with another peak ~1 Hz away and then we lost lock shortly after, for unrelated reasons. 

Briefly, the damping set up: We grab the mechanical mode signal from the OMC transmission DCPDs (H1:OMC-PI_DCPD_64KHZ_A) and send it to the relevant end station, downconverting before the trip and upconverting after using synced oscillators set approximately to the known mechanical mode. There, the mechanical mode peak is tracked with iWave. Output is run through a damping filter for gain control and finally sent to actuate on the UR and LL quadrant of the ETM LNLV ESD. Overall, we get early detection of PI from the OMC and actuation on the test mass with the exact equal but opposite mechanical mode frequency that is ringing up, enabling damping to happen earlier in the lock aquisition process before PI has as much time to ring up. This is necessary as we increase power yet remain working with relatively low actuation force from the ESDs. 

PI at 15520: While working with 15540.6 Hz, we witnessed a mode at 15520 begin to ring up as well. During a second 24W lock, we allowed both to ring up ~15 min; they grew rapidly at similar rates, ultimately producing a strong 20Hz comb and breaking the lock. Will investigate (and attempt to damp) more this weekend.

We didn't get another good lock to test on tonight and we're still working out issues so I've left the damping system in manual mode and have turned the ETMX ring heater back on. 

3:37UTC

4:09UTC

5:37UTC

.3micron Alarm also at EX

4:31UTC

5:03UTC

Following up on yesterday's restart of CW HW injections with a new actuation scheme,
here are comparisons over 24-hour intervals of the excitation channel H1:CAL-PINJX_HARDWARE
with what it was previously when a time-domain inverse actuation filter was used.
One benefit for transient search groups is that if sporadic CW injection dropouts are seen again in O2, 
they should not induce nasty glitches in DARM (see figures 11-13 below).

The bottom line for CW searches is that things look close to what is expected, but the amplitude of the 
highest-frequency pulsar injections (above 1 kHz) are significantly lower than before. 

The small residual discrepancy does not seem to be explained by the difference
between the old and new inverse actuation filter curves that Evan G. posted yesterday. Perhaps both the old and new inverse actuation filters simply amplify
the 1000-2000 Hz band too much (by 20-30%)? 

The figures below show 24-hour second-trend plots of the excitation channel envelope and
4-minute spectrum snapshots taken at 6-hour intervals, along with samples of sudden shutting
off of the injections.

Figure 1 - 24-hour trend (min/mean/max) of the channel for old actuation, showing the envelope of injections,
which is affected by the rotating antenna pattern of the interferometer w.r.t. 15 different
points on the sky with various intrinsic source polarization and strengths.

Figure 2 - 24-hour trend for new actuation - one can see a small drop in amplitude, driven by the highest
frequency pulsars for which the inconsistency between old inverse actuation filter and new actuation function is largest

Figure 3 - 4-minute spectrum at 22:34 UTC on May 24 (old actuation)

Figure 4 - 4-minute spectrum at 22:30 UTC on May 25 (new actuation) - approximately one sidereal day later

Figure 5 - 4-minute spectrum at 04:34 UTC on May 25 (old actuation)

Figure 6 - 4-minute spectrum at 04:30 UTC on May 26 (new actuation) - approximately one sidereal day later

Figure 7 - 4-minute spectrum at 10:34 UTC on May 25 (old actuation)

Figure 8 - 4-minute spectrum at 10:30 UTC on May 26 (new actuation) - approximately one sidereal day later

Figure 9 - 4-minute spectrum at 10:34 UTC on May 25 (old actuation)

Figure 10 - 4-minute spectrum at 10:30 UTC on May 26 (new actuation) - approximately one sidereal day later

Figure 11 - Glitch induced by sudden shutoff of CW injections with old inverse actuation filter

Figure 12 - Vertical zoom of glitch

Figure 13 - No glitch induced by shutoff of CW injections with new direct application of inverse actuation function


Note that the new trend (Figure 2) is a little smoother than the old one, as expected, 
without the amplification of tiny glitches seen with the old inverse filter. Another
manifestation is the much cleaner noise floors seen in the new spectra, away from
the injected lines. 

Peter in PSL enclosure
14:55 UTC Jeff B. moving chiller with forklift
15:13 UTC Lock loss after sitting on LOCK_ALS. A short time after the ISI ITMX stage 1 and 2 watchdogs tripped.
15:23 UTC Filiberto to beer garden to take measurements for running cables
15:33 UTC Jeff B. done
15:43 UTC Filiberto done
15:56 UTC Peter to LVEA to toggle NPRO noise eater switch
16:00 UTC Peter back
16:12 UTC Peter to PSL enclosure
17:10 UTC Fire department truck through gate
17:22 UTC Betsy looking for parts in LVEA west bay
17:35 UTC Jim W. to end X to install anemometer in desert (WP 5902)
17:32 UTC Peter done
17:44 UTC I toggled the NPRO noise eater switch
17:46 UTC Dave loading ASC filter modules
17:55 UTC Started attempting to lock
18:09 UTC Lock loss on CARM_5PM
18:28 UTC Lock loss on ENGAGE_ASC_PART2
18:47 UTC Re-requested READY_FOR_HANDOFF for OMC_LOCK node in order to get to DC_READOUT
The ISS first loop did not engage because the PSL AUTOLOCK was off. Kiwamu turned it on.
18:50 UTC Jim W. back
19:55 UTC Tour leaving control room
20:06 UTC Travis to end Y to reset camera
20:44 UTC Have been sitting at DC readout. Commissioners back. Evan H. changing 9Mhz modulation depth.
20:47 UTC Travis back
21:24 UTC Evan H. done
Going to NOISE_TUNINGS for Sheila and Terra to run measurements
Got stuck on increase power. Sheila changed guardian code to continue.
22:11 UTC Kiwamu and Nutsinee to CO2 Y table to remove beam block
22:15 UTC Jim W. to end X to retrieve anemometer from desert
22:44 UTC Kiwamu and Nutsinee back. They did not remove the beam dump.
22:47 UTC Jim W. back
22:53 UTC Kiwamu and Nutsinee back to CO2 Y table

The laser power guardian checks that the laser power is within 15% of the requested power, and doesn't return true unless it is.  The rotation stage isn't always this accurate (right now the requested angle matches the measured angle, but the requested power is 12W instead of 10W).  Now that we are powering up in multiple steps, this means that the guardian gets stuck with a warning to adjust the rotation stage by hand or search for home.  

We edited the threshold that is used to check the power, so now it will return true if we are within 25% of the requested power. 

Following a two month hiatus we have gotten the daily archival of H1 running DAQ and filter files running again.

This runs as user root on script0, as a cronjob running at 27 minutes past the hours of 9,4,8,12,16,20.

Many thanks to Evan for reminding us that this service was not operational.

https://daqsvn.ligo-la.caltech.edu/websvn/

After several loads of the ASC DHARD filter, the archived H1ASC.txt file increased in size from 4,000 lines to 117,000 lines overnight. Now that the DAQSVN archiver is running again, this becomes an issue when someone tries to display the differences in the loaded filters. These problems can be avoided by doing a full filter load (from the GDS_TP MEDM screen) if you see the difference list getting out of hand.

Attached are 7 day pitch, yaw, and sum trends for all active H1 optical levers. Big dips on Tuesday May 24 caused by the recentering of the OPLEVS.

All the DBB cables were checked that they were connected properly (they were).  The incident power into the
diagnostic breadboard was adjusted to be ~110 mW - it really should be 135 mW.  However at this lower power
level, the interlock still tripped.  The interlock tripped even though the shutter did not open.  I blocked
the input hole to the diagnostic breadboard so that no light could enter.  Under this circumstance the interlock
still tripped.  So obviously it wasn't a light level associated problem even though the interlock message
indicated it was.

    I turned off and then on the two AA and AI chassis associated with the diagnostic breadboard.  This seems
to have reset the problem.

    That said, there's still some work to do to bring the diagnostic breadboard truly back.

   The signals for the Diode Room chiller flat lined at 23:09 on the 22nd. Need to reboot the H1PSLCTRL0 computer. As this will take down the PSL will do the reboot early Friday morning. 

Sheila, Keita, Haocun

We took several more measurements on 90MHz signals at AS port yesterday.


In summary, the noise at 90MHz is really large compared to signals. Even when the MC was unclocked, the spectrum from RF IN had a peak of -88dBm at 91MHz, and the signals were around -71dBm both at RF in and RF MON when the IFO was locked.
There are large signals at 54MHz in RF IN (-45dBm), and -68dBm in RF MON. We put in an 91MHz Bandpass Filter (Lark Engineering MC91.5-H2.5-3BA), but this did not help with the noises at 91MHz. (RF IN: -78dBm; RF MON: -70dBm @91MHz)

Last night, we ran a quick TCS test where we attempted to minimize the intensity noise coupling to the DCPDs by changing the CO2 differential heating.

It seems that the following CO2 setting gives a much better intensity noise coupling when the PSL power is 25 W:

• CO2X = 460 mW
• CO2Y = 0 W

This did not improve the recycling gain so much. It seems to have increased by 2% only.

According to a past measurement with a lower power PSL of 2 W (alog 26264), a good differential CO2 power had been found to be P_{co2x} - P_{co2y} = 270 mW (or probably less than 270 mW because I did not explore the lower differential power).

This could be an indication that ITMY has a larger absorption for the 1064 nm light such that the differential self-heating linearly changes as a function of the PSL power. We should confirm this hypothesis using the HWS signals.

[The test]

No second or third loops engaged, DC readout, no SRC1 ASC loop.

• 3:34 UTC, full resonance with 2 W PSL
• 4:12 UTC, PSL --> 25 W
• 4:24 UTC,  CO2Y 260 mW --> 0 mW
• 4:49 UTC, PSL --> 22 W for letting the 0.5 Hz instability go away
• 4:56 UTC, CO2X 480 mW --> 790 mW
• 5:12 UTC, lock loss

Drastic reduction of the intensity noise coupling was observed mostly between 4:24 and approximately 5:00, indicating that reducing the CO2Y power helped improved the coupling. After 5:00 UTC, we did not see a significant reduction. This may mean that we might have been already close to an optimum point where the coupling is minimized. The attached shows DARM spectra from various time during the test.

A broad peak at around 400 Hz is my intentional excitation to the first loop with band-passed gaussian noise in order to check the coupling to the DCPDs. As shown in the spectra, the reduction from the beginning to the end of the test is about a factor of 5. As reported in 27370, broad noise above 100 Hz up to several kHz is indeed intensity noise and therefore we see the noise floor in this frequency band decreasing too.

Kiwamu, Sheila, Hoacun, Evan

We've worked on all four hard loops today.  

First we designed a new compensator for CHARD P, which roughly inverts the plant at 2W and should be stable all the way to 50 Watts according to the model. (Screenshots of filter change and before and after OLG measurements attached.)

We tried this for DHARD, but it was not stable durring the CARM offset reduction.  Instead we made a filter that is the ratio of the new compensator to the old, which is engaged on resonance.  

Then we had a look at the hard yaw loops, and adjusted the boosts in both loops to move the zeros to higher frequencies.

This is all in the guardian.  

Things not in the guardian:

We have seen several times that engaging the ISS 3rd loop supresses the CSOFT P instability (engage second loop output, set 3rd loop gain to 0.04).    I tried once to engage it at 20 Watts, and it broke the lock.  

When we approach 40 Watts, there is an instability at nearly 2 Hz in yaw that breaks the lock.  It is clear from the transfer function of both CHARD and DHARD yaw that there is a problem here.  I tried a lag filter (FM4 in both DHARD and CHARD Y) to avoid the instabilites.  These can come on by hand at 20 Watts, and do avoid the instability  but just shift the problem to little bit of a lower frequency where we have a little gain.  

After adding these filters I became unable to get test points using DTT (the test points were all full for ASC, so I cleared them, but I still couldn't get anything from dtt.  I tried closing my dtt session and starting over, but that didn't work either).

I tried powering up one last time, it looked like an instability in DHARD P was the problem this time. 

I turned off the XARM ring heaters to prepare for a PI test tomorow. 

BSC5 annulus IP is flickering between red and green state. 

BSC8 aIP was in the red a few days ago, but seems to have recovered. 

Transitioning over to the new, improved inverse actuation filters (see LHO aLOG 27176), I removed the old filters from PINJ_HARDWARE and installed the new inverse actuation filters into the PINJ_TRANSIENT bank. Since the CW injections will apply the inverse actuation function to condition their signals before sending it to the PINJ path, we don't want the filters in PINJ_HARDWARE any longer.

CW injections are running right now using this new actuation function. Keith R. and I made a test of this earlier to verify the output was roughly correct (Keith will post an aLOG about our work). He wants to see this running over the next few days to gain confidence that the injections are operating normally.