Evan, Krishna, Alexa, Dan, Kiwamu,

At some point in this evening, we noticed that the IMC kept dropping its lock for some unknown reason. It turned out that the HAM2 ISI sensor correction was amplifying seismic at 0.3-ish Hz which resulted in a large drive in MC2 to keep it locked. So we turned the sensor correction off for now. This fixed the issue.

Even though the MC2 coil DACs were not saturating, somehow the motion was big enough to unlock the IMC. It is still unclear why it could unlock. Anyway, after turning off the sensor correction, the amont of drive in MC2 suspension reduced by a factor of 5 or so and IMC became able to stay locked. With the sensor correction on, the MC length was moving approximately +/- 5 um according to IMC_X displacement monitors. We don't know what changed in the HAM2 ISI sensor correction as it has been running fine for a while recently. Only thing we immidiately noticed was that the seismic freq-limited RMSs were pretty high in 0.1-0.3 Hz and 0.03-0.1 Hz bands in this evening. The attached is a time series of the IMC_X signals when we did a simple test of turning on and off the sensor correction in the HAM2 ISI. Since we were a bit rough for turning on and off the correction, it gave a transient when switcing it, but one can still see that when the correction was running, the IMC_X signal increased by roughly a factor of 5.

S. Dwyer, J. Warner, H. Radkins, K. Venkateswara

We did a quick test of sensor correction (SC) along X direction to Stage 1 ISI, previously described in 15146. This attempts to use the ground seismometers located near the test mass chambers in feed-forward like manner to reduce the cavity motion. Sheila and Jim aligned and locked the X-arm using the green laser and data was recorded with SC OFF and ON.

The first pdf shows the signals with SC OFF and the second shows them with SC ON. The signals shown first are the Stage 1 T240s (inertial sensors), the CPSs (positions sensors) and the X arm control signal. The inertial sensors indicate a significant reduction in motion of Stage 1 on both ETMX and ITMX between 50-500 mHz. The microseismic motion is suppressed by factor of ~4. Yet, surprisingly, the X-arm control signal looks almost similar. The oplevs shown on pages 3, 4 indicate that the angular motion of the optics was unchanged so perhaps it might be limiting the control signal.
 

K. Venkateswara

I revived the BRS system after a crash towards the end of last week. It had successfully worked for a period of 16-17 days since the last restart.

As described in SEI alog 638, I've modified the pendulum response-inversion filter. I've also modified the tilt-subtraction scheme as described in the subsequent comments to the log. A high-pass filter at 5 mHz has been added in the sensor correction path (in the calibration filter bank) to roll off the low frequency increase in noise.

I've attached a pdf showing the output of the new tilt-subtraction scheme. The red 'super-sensor' curve looks similar to the blue ground curve, so we'll have to wait for a windy period to see if the tilt-subtraction has been improved or not.

Dave, Evan

Here is a larger scan of the the Y arm loss as a function of ETMY spot position. I tried to get out to a 6 cm radius from the nominal, but eventually the alignment was so bad that the arm broke lock. Also, I've masked out points for which the TRY dc value is less than 10 ct.

Also attached is Friday's measurement, with the colors rescaled to match the colors of today's measurement. Note that Friday's measurement is a smaller spiral. It's hard to know how to compare these measurements, but I've attached another plot where I suggest where Friday's small spiral may fit into today's big spiral.

Note that the zero points of the displacements are not consistent between different measurements; each time I have simply aligned the arm to get good buildup and then started the spiral. Attempting to reproduce the pointing from day to day would be a much more involved process.

Ran DBB scans of the PSL. The plots are attached below.

Day's Activities:

• Observation Bit was in Commissioning state
• 7:15  Cris in LVEA
• 9:50 Travis in HiBay to look at First Contact supply
• 9:12 pem cabling & hepi pressure sensors (filiberto)
• 9:45 EY Dust Monitor (Jeff B)
• 9:55 EY & EX for Oplev photos (Doug)
• 10:10 LVEA West Bay parts hunt real quick (Mitch)
• 10:10 TCS part search (Andres)
• 10:15 - 1:10  Beam Rotation Sensor work at EX (Jim W, Krishna)
• 10:18 Elli at EX/EY to grab cables off ISCT EX/EY
• 1:15 Replace chilled water booster pump
• 1:59 MX Instrument Air
• 2:47 HAM ISI measurements (Jim W)

Laser Status: 
SysStat is good
Output power is 33.1 W (should be around 30 W)
FRONTEND WATCHdog is Active
HPO WATCH is RED

PMC:
It has been locked 7 day, 21 hr 39 minutes (should be days/weeks)
Reflected power is 2.4 Watts, and PowerSum = 25.8 Watts.
(Reflected Power should be <= 10% of PowerSum)

FSS:
It has been locked for 0 days, 0 h and 17 min (should be days/weeks)
Threshold on transmitted photo-detector PD = 1.555V (should be 0.9V)

ISS:
The diffracted power is around 5.700% (should be 5-15%)
Last saturation event was 0 days, 0 h and 15 minutes ago (should be days/weeks)

The HEPI Pumps stopped due to a level trip in the reservoir fluid height.  I did a 100% scan of the system in the LVEA and found no evidence of a leak.  I should have done similar in the MR but went back to my previous assumption that the fluid level declines were from the known motor drips on PS8 (1.)  I had lowered the trip position to its lowest level last Tuesday so I proceeded to add fluid (Best to do while pumps are off.)  Added ~2.4 gallons and then got the pump stations back running.

It seems someone else had seen a leak on the mezzinine previously--Just before leaving I noticed something (can't remember exactly what) behind the blue drum behind the reservoir, on the floor was an absorbent pad and other puddles.  I first thought TCS but no it was HEPI fluid.  I found a 5 second drip coming from the pipe/hose joint at the electrical break.  I tightened this clamp a bit and will regularly monitor for a few days.  I suspect the leak rate may have increased over time but if it had started at full rate, it would take 105 hours to leak a gallon.  Since last Tuesday, I'd say the level had to drop about 3/8" or 0.3 gallons.  Given the mess I cleaned up this morning, that seems about right.

So, I don't know when this leak started, it may have been much slower for a long time.  Was the absorbent pad just luckily in the right spot or had someone put it there?  Did someone tell me about it (a long time ago,) possibly?

• In-vac incursion discussion:  Most likely next week
  • HAM1 1-day: 
  • EY to clean ETMy (first contact "ring", and various types of spots)
    • Earliest could start is wed (maybe aim for mon)
  • Try not to forget other activities:  Camera housings at EX?
• Craning operations (3ifo work) planned for Tues Maintenance
• Cleanroom tape leaving residue on vinyl cleanroom curtains
• HEPI situation (Pump Stations down Sunday morning) brought up.  Hugh could do some major work (including filling resevoir & several investigations), or can work to just get back up today & do major work during potential vent next week.

• Intent Bit was in the Commissioning State upon arrival
• ISI Trips for:  BSC1, 2, 3. 
• HEPI Trips for:  all corner station HEPIs---> pointing to Pump Station Issue (went down around 12:15am Sunday morning).  Hugh will investigate and will take opportunity to add fluid to the system.
• SUS Trips:  ITMx

model restarts logged for Sun 07/Dec/2014
2014_12_07 15:28 h1fw1
2014_12_07 22:42 h1fw0

Both restarts unexpected. Conlog frequently changing channel report attached. FYI: H1:ALS-Y_REFL_SERVO_IN1EN is being toggled every 2 seconds by a non-guardian script.

no restarts reported. Conlog frequently changing channels list attached.

Over the past few days I optimized the damping filters for the HTTS suspensions (RMs, OMs) and the OMC SUS.  For the most part this was an exercise of copying the filters from L1 and making sure the gains were sensible.  (For the HTTS, I used the filters that Rana had set up at L1.)  I've changed the damping gains and filter settings for the DAMP loops on the following suspensions: RM1, RM2, OM1, OM2, OM3, and OMCS.  We should update the safe.snap files on Monday.

For each optic and each damping loop I set the gains using the impulse response to judge the Q of the fundamental modes.  The first image attached shows the OM1 response in L, P, and Y to impulses.  The Q in each case is about 5.  (I applied the impulses using the LOCK filter banks, and thanks to Koji's diagonlization of the LOCK inputs to the OMs there is very little DC coupling between the DOFs.)

The second plot is damped spectra for the OMs, compared to the damped spectra before I changed the filters.  The OMs were somewhat overdamped before the changes.

For some reason the RM1 damping loops are different by a sign from the other HTTS, I'm not sure where this sign flip is coming from.  For RM1 the damping gain is 1.0, for all the other HTTS it's -1.0.  The gains that are hard-coded into the 'gain' filter in each L,P,Y filter bank are the same for each optic.

Once I finished with the HTTS suspensions I worked on the OMC.  H1's OMCS hadn't been damped before; I tried to do some clever filter work but in the end I found the imported filters from L1 worked well (a zero at 0Hz, two poles at 30Hz, and a 4th-order elliptic rolloff at 50Hz.)  The one difference is the YAW loop, I added a boost filter at 0.54Hz.  The third plot attached shows the damped and undamped spectra of the OMCS in the six degrees of freedom.  The gains for each DAMP filter bank were set using the impulse response.  They are:

I also went through the OSEMINF filter banks for each optic and made sure each had a comb(60,30,-50,4).

Evan, Dan

We tested the OMC's fast PZT shutter function today.  It works!

We followed the procedure that Zach described for the OMC at L1.  On ISCT6, we installed a PDA255 (50MHz) on the OMC TRANS beam path.  Then we tee'd off the input to the 'trigger' port on the OMC PZT driver chassis.  (The trigger input to the driver chassis comes from the shutter logic controller box on top of ISCT6; the trigger PD is ASC-AS_C.)  With the OMC locked on a single-bounce, we closed the shutter by hand using the Beckhoff controls, and triggered a fast oscilloscope on the falling shutter logic signal.  Since we triggered on the output of the shutter logic box, we essentially measured how long it takes the OMC TRANS to drop to zero after the shutter logic is flipped.  (There will be additional delays due to the logic electronics inside the shutter controller; also the response of the AS_C sum output to a spike in power is finite.  We assume that these delays are less than ~1 millisecond, which is the prescribed shutter performance from T1000294.)

The OMC TRANS signal drops to 10% of the full light level zero 3.84 microseconds after the shutter logic output switched to the closed condition.  This was calculated using a sigmoid fit to the PD data, see figure.  We repeated the test three times, and the results in each case were the same to within 10 nanoseconds.  Plots and data files are attached; Channel 1 is the output of the shutter logic controller (5V is nominal/open state, 0V is triggered/closed state), Channel 2 is the PDA255 on the OMC TRANS path.  The drop from full lock to no transmission is less than a microsecond, the other 2.84 usec of the delay must come from the LV path on the PZT driver board.

One more thing we need to do before the HAM6 shutter electronics are functional for full IFO locks is swap a resistor on the AS_C transimpedance board.  We want to set the shutter threshold at 1 W into HAM6, and AS_C gets 2.5% of the light going into the chamber, so the threshold should be 25mW.  Currently the AS_C sum output calibration is 200 V/watt of power on the QPD.  With this calibration the threshold level should be 5 volts, but due to some factors of five in the Beckhoff settings and the shutter logic box that I don't understand, we only have a range of 0-2 volts for the threshold.  So we need to swap R23 on the AS_C transimpedance board again, for a 420 ohm resistor.  With this change the threshold for the trigger will be 1.6V.

no restarts reported. Conlog frequently changing channels list attached.

SudarshanK, TravisS, EvanH, AlexaS, RickS

Using the Pcal beam localization cameras at both end stations, we took images of the ETM surfaces under three conditions: IR and Green resonating; IR only resonating, and Green only resonating.

Attached below are two composite images composed of four separate images taken with the same camera settings:
Upper Left: Xarm Green
Lower Left: Xarm IR
Upper Right: Yarm Green
Lower Right: Yarm IR

The images in the first composite were taken with the following camera settings: F8, ISO 200, 30 second exposure, WB-cloudy.

For the second composite image the aperture was F29 (~13 times less light)

The Yend camera was re-focused for the IR-only images, but the Xend camera was not re-focused.