The CP3 refill reminders (emails and cell phone text messages) have been rescheduled from every other day (actually every odd-day of the year) to Mon, Wed, Fri. This means that reminders will no longer be sent during weekends. The change was requested by the vacuum group.

13:55 UTC Chris S. opened high bay outside door for approx. 30 min to remove barrels
Mode cleaner lost lock, NPRO noise eater went out of range
15:22 UTC Jim W. to LVEA to toggle noise eater switch
15:28 UTC Jim W. done
15:55 UTC Betsy to LVEA to look for equipment
16:11 UTC Travis to HAM6 with tape measure
16:22 UTC Jim B. to staging building
16:28 UTC Travis and Betsy done
16:42 UTC Nutsinee and Kiwamu to TCSY CO2 table
17:02 UTC Jeff B. and Jason using forklift by mechanical room
17:32 UTC Jim B. back
17:55 UTC Keita and Haocun to HAM6 to take measurements
18:02 UTC Jeff B. and Jason done
18:09 UTC Kyle to LVEA to look for property tag
18:11 UTC Boom lift delivery through gate
18:55 UTC Kyle back. Kyle going to mid Y.
19:05 UTC Nutsinee and Kiwamu back
19:25 UTC Kyle back from mid Y
20:05 UTC Jeff B. using forklift near mechanical building
20:21 UTC Christina to open OSB receiving door
20:31 UTC Chandra and Gerardo to mid Y to fill CP3 and look at equipment in building
20:51 UTC Kiwamu and Nutsinee back to TCSY CO2 table
21:01 UTC Keita to CER to check ISC racks
21:13 UTC Jeff B. done
21:13 UTC Chandra and Gerardo done

Sheila and Evan H. have been troubleshooting locklosses. Nutsinee and Kiwamu have been working on TCSY CO2.

Lowered LLCV value from 20% to 19% because exhaust pressure was reading 1.2 psi. 

Chandra and Gerardo made arrangements for CP3 fill on Monday, Memorial Day.

2pm local

1/2 turn open LLCV bypass - took 22 sec. to overfill CP3. 

Jim, Dave:

Thursday afternoon and this morning we brought the Staging Building SUS test stand back to life. The front end machine (bscteststand2) and its IO Chassis started with no problems. Most of our work was in getting the workstation running to permit DTT and DATAVIEWER to run. The original SUS workstation, which used to be in the office area, has been repurposed. We located the old SEI workstation in the DTS and pressed that into SUS service. In order to run the workstation outside of the clean area but not in the office, we have temporarily setup in the communications closet. Next week when the area behind the large roll-up door becomes available we will move the workstation there to avoid the closet's cooling issues.

Originally a NAT router (bisbee) in the FEC rack was connected to the GC switch via a wall outlet. We have decommissioned the NAT router, and used the ethernet run to the closet as the way of hooking the workstation up to the iMac and the FEC. We will not be replacing the NAT router, this test stand will no longer be accessible from GC.

Next week Betsy will be able to use the iMac in the clean room to X-foward DTT sessions running on the workstation.

Attached are the trends for the BRSY Drift.  We are close to -10000 counts and doing about 5000 counts per week.  Next weekend power outage may suggest we just wait until after power recovery.  Will check with UW whether we should recenter before or after as well as power recovery procedure.

TCS CO2 Y arm alignment in the morning (Nutsinee)

Vacuum group will replace remaining pneumatic LLCV actuators with electrically driven actuators on Tuesday (Chandra)

Boom lift arriving on site this morning from Sun Valley rentals (Bubba)

To fix a problem with the readouts for the diode chiller flow and conductivity, the PSL Beckhoff computer was
rebooted this morning.

    I also took advantage of the opportunity to reset the clock on the computer from Central European time
to US Pacific.

    At first glance it looks like rebooting the computer fixed the signal(s).

    The laser was brought back to life, by the time I got back to the Control Room all the servos were locked
and engaged.



Jeff, Peter

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. 

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.