J. Kissel, K. Venkateswara, K. Izumi, J. Warner

While Kiwamu was trying to lock the Michelson, several things went wrong, but it uncovered a flaw in the new gain switching of the GS13s that has been implemented in the Guardian (see LHO aLOG 15537. Here's what happened.
(1) Kiwamu incorrectly brought up the BSC ISI in "fully isolated," which turns on stage 2 isolation loops, and switches the GS13s to high-gain mode.
(2) As expected, while trying to acquire MICH lock, impulses sent to the SUS BS kick the cage as well, which is attached to the BS ISI ST2, and trips the ST2 on the GS13s watchdog.
(3) We then reset the watchdog, and switched to "isolated damped," and this triggered the new guardian feature to *start* switching the GS13s back to low gain, but with MICH still trying to lock, impulses would still trip the watchdog before guardian had the chance to switch *all* of the GS13s gains. 
(4) This, trigger-happy watchdog resetting, and guardian half transitioning, caused a nasty loop of guardian sloshing the GS13 gains back and forth between high and low, which, with MICH impulses, continued to trip the watchdog.

I attach a plot of one of the WD trip, which clearly shows that the V3 GS13 had failed to have its gain switched to low. 

We should 
(a) look the new code to make sure there isn't a bad loophole regarding the GS13 gain switching when transitioning from "fully isolated" to "isolated damped"
(b) look for ways to increase the switching speed, or add a pause / check that the switch has occured on all GS13s before proceeding with the transition
(c) remember that these are physical, several thousand pound systems -- if you have to reset watchdogs repeatedly something is wrong and you don't know why, don't just blindly continue to mash the reset button, figure out what's wrong, or do what Kiwamu did and ask an expert!

#justwait

Thomas, Stefan, Jeff, Kiwamu, Elli

Continuing along the same line as yesterday's work on PR3 (alog 15727), we have designed high-bandwidth (<10Hz) actuation filters for the PRM.  These filters are applied to H1ASC-PRC1P and H1ASC-PRC1Y in the central part of the ASC WFS servo.

The filters added to ASC WFS central are called 'PRM^-1' and are:
H1:ASC-PRC1_P:   zpk([0.2+i+0.9;0.2-i*0.9;0.05+i*3.41;0.05-i*3.41],
                [0;0.2+i*2.75;0.2-i*2.75;0.125+i*9.99922;0.125-i*9.99922],1,"n")
H1:ASC-PRC1_Y:     zpk([0.04+i*1.08;0.04-i*1.08;0.1+i*2.08;0.1-i*2.08;0.05+i*3.43;0.05-i*3.43],
                [0;0.15+i*1.8;0.15-i*1.8;0.05+i*3.3;0.05-i*3.3],1,"n")
Some old unused filters were also removed.

Low-pass filters called 'RLP17' were added to the PRM M3 locking filters in pitch and yaw:
H1:SUS-PRM_M3_LOCK_P:  zpk([4+i*119.933;4-i*119.933],[6.78887+i*13.9134;6.788887-i*13.9134],1,"n")
H1:SUS-PRM_M3_LOCK_y:  zpk([4+i*119.933;4-i*119.933],[6.78887+i*13.9134;6.788887-i*13.9134],1,"n")

Fabrice, Hugh, Dave:

we restarted the models h1isiham3 and h1hpiham3 as part of the seismic investigation of this chamber. No new filters, code or daq configuration were applied, this was a simple restart.

LVEA: Laser Hazard
Observation Bit: Commissioning  

08:00 Cris – Delivering garb to End-X
08:40 Doug – OpLev work at HAM4
08:51 Kyle & Gerardo – Roughing BSC10
09:00 Betsy, Travis, & Rick – At End-X
09:10 Fabrice – BS & HAM3 Testing
09:13 Filiberto & Aaron – PEM cabling work in the Beer Garden
09:30 Karen – Going to End-Y
09:55 Kyle & Gerardo – Back from End-Y
10:18 Jim – Going to End-X to unlock HEPI & ISI
10:30 Shutdown dust monitor at HAM1
10:36 Karen – Back from End-Y
10:40 Dale – High School tour in control room
11:19 Dave – Going to End-Y to adjust cameras
11:21 Jim – Back from End-X
11:45 Betsy, Travis, & Rick – Back from End-X
12:50 Jim – Going to End-X to unlock HEPI
12:52 Filiberto – PEM and cabling work in Beer Garden and along spool arms
13:50 Dave – At End-X to adjust cameras
14:02 Kyle, Gerardo, & Bubba – End-X Install West door, connect pump cart and pump annulus
14:05 Dave – Back from End-X
14:44 Filiberto – Out of the LVEA
14:47 Dave – Restarting HAM3 models
15:28 Rick – Taking Mike R. and friend on tour of LVEA
15:40 Kyle, Gerardo, & Bubba – Finished with BSC9 door install, started pumping annulus 

Jim, Hugh, Krishna, Jeff, Fabrice:

We keep investigating the sensor corrction issue on HAM3. What we found yesterday is that it depends on which blends are engaged. We can't explain why yet. We did additional tests today:

- we turned off all CPSs of all HAM-ISI and BSC-ISI in the corner station. No change.

- we checked the jumpers of all HAM3 CPS boards. All good.

- we tried to apply large offset in case it would reduce some kind of cable touching/rubbing (+/-400 um in HEPI Z, and +/-400 um in ISI X,Y, Z). No change.

Finally, we tried to do the Z sensor correction to HEPI. In the plot attached:

- Red curves is HAM3 ISI isolated, no sensor correction

- Green Curve, we turn ON the sensor correction in X and Y to the HAM-ISI

- Blue Curve, we also turn on Z sensor correction to ISI. The 0.6 HZ peak shows up. For some reason it also reduces X at the microseism.

- Brown, we do the Z sensor correction to HEPI instada of ISI. The peak is still there in the CPS, but not in the GS13. It's unclear why.

The last configuration looks good from the GS13s,  but it's unclear yet how good it is for the cavity. More info on that is coming.

The information we received from Hanford ops indicated that hauling would not occur on day shift or swing shift today, 12/19.  The 1-3Hz seismic trace during the day today looks pretty noisy, however, as if hauling is occurring.  I'll pursue this next week -- perhaps there's other activity underway nearby.  No hauling is scheduled for the weekend.  Next week the drivers are scheduled to work day and swing on Monday and Tuesday and then go out for the remainder of the week and the weekend.  I suspect that they'll use a similar schedule during the week of Jan 1.   

Kyle, Gerardo, Bubba -> Door 

Kyle -> Annulus 

Will begin "rough" pumping X-end first thing Monday morning

F. Matichard, H. Radkins, J. Warner, K. Venkateswara

Due to the problems described in 15690, Z sensor correction to the corner station BSC HEPIs was causing excess tilts at low frequencies. Based on directions from Fabrice, Hugh and I ran tilt decoupling measurements described in 15726 and fixed this to some extent. The pdf attachment (BS_HEPI_Tilt_Decoupling.pdf) shows the effect of the tilt decoupling at the Beamsplitter. The measurements show the X, Y  CPS signals with no sensor correction, with sensor correction and finally with sensor correciton and tilt decoupling. There is still room for improvement and a more careful and longer measurement might reduce this further.

For the moment this seems to be good enough to keep MICH locked with perhaps some improvement in the MICH_OUT as seen in the image attached (MICH_OUT.png). The benefit of the Z sensor correction can be seen in the second image (BS_Zsensor_Correction.png). The improvement is not as significant as some of the other chambers. We should investigate more to see what limits the subtraction.

Edit: I made a mistake in the labeling of the lines. The blue and green labels are switched and so are the blue/cyan and pink labels. In summary, the sensor correction increased x and y motion by a factor of ~10 and ~40 respectively and tilt decoupling reduced it by a factor of ~3 and ~8. A more careful/longer approach may reduce it to the original levels.

Betsy, Travis, Jason, Rick

First Contact was peeled from the ETM surface this morning.  No First Contact remnants were observed on the surface.  

Particulate counts, using the "Green Lantern," were in the 2-5 particles per square inch range, down from the 5-10 particles per square inch seen before applying the first contact.

The composite image attached below contains six images.  The upper row of three were taken before applying the First Contact and the lower row of three were taken after the First Contact was removed.

For all images, the surface of the ETM was illuminated with a green LED flashlight.  For the four images on the left the flashlight was held by hand.  For the two in the right, the flashlight was set in the Arm Cavity Baffle in an effort to make the illumination the same for both images.

model restarts logged for Thu 18/Dec/2014
2014_12_18 11:30 h1fw1

unexpected restart. Conlog frequently changing channels report attached.

Blow down dewpoint -26C

Fabrice Krishna Hugh.

Krishna was suspecting that RX tilting on ITMY and the BS was impacting the HEPI Z Sensor correction results.  Sure enough, when checked it was most coupled on the BS Z to RX and next on ITMY HEPI Z to RX.  The other couplings, that is, HEPI Z to RY, and for ITMY both HEPI Z to RX & RY, where less by about a factor of 10.

The Measurement

HEPI Z is driven with a 0.001 to .1 band pass excitation (see attachment 1) looking for coherence with ISI Stage1 T240 X & Y.

The HEPI is in normal configuration, Lvl1 position loops but with sensor correction off.

The ISI Stage1 all dofs are put into high blend (T750) and its sensor correction is also off.

Once a baseline of the existing HEPI Z to ISI Stage1 T240 to RX & RY coupling is established as seen by the T240 Y & X, the HEPI is then Tilted in RX & RY with a smaller magnitude but similar bandpass to see the actual tilt of the ISI Stage1 when HEPI is tilted.  The Decoupling factor is computed by the ratio of the former to the latter: RX_z/RX_rx.  This correction goes into the IPS Align matrix.

Results

See attachment 2 for ITMY.  The left three plots are the TF data for inline tilt on ITMY, this is the Y direction caused by RX; the three right plots are for the crossline tilt RY showing on X. The first step is shown in blue: the area below 0.1 to 0.01hz with good coherence is our tilt coupling.  Notice on the right side, there is poor coherence and the TF magnitude is 10x smaller than the tilt in the Ydirection seen on the left side.

The green traces are the direct tilt measurement HEPI RX(RY) to ISI RX(RY).  Picking a few magnitude points from the blue & green traces in the area of interest and averaging the ratios gives the decoupling factor blue/green= 0.23/46(e.g.) == -0.0049 with the sign coming from the phase which are ~180 out of phase.

The brown trace (only on the left side) shows the reduction with the decoupling factor in the matrix (see last attachment) when the first measurement is repeated. (I failed to save the coherence for this but it was reduced just above 0.8 from the near 1 at the start (blue.)  This indicates there may be more improvement to be made but it will be time consuming and may not be worth it.  The improvement though is clear, about a factor of 10.

Time constraints (commissioners) prevented a brown results curve measurement for the Z to RY tilting but I have the data to calculate the ratio.  We expect the improvement to be minimal as the coupling is already low.

Secretary notes from BSC9 today:

• The chamber door was pulled by Gerardo/Kyle/Bubba.
• ~20 mins later, with the billowing C3 door cover on, I reached in and took particle counter counts of 30 - 0.3um, 20 - 0.5um, 10 - 0.7um.  A pretty clean sample.
• I reached in an wiped ~2/3 of the floor.
• Jim locked the HEPI.
• Jim locked the ISI.
• Travis, Jason and I went into the chamber.
• We attached the locking bracket to the ACB and let it swing back to it's natural hanging position, giving us a bit of room to work, yet not occulting the pcal camera view.
• We removed the vertical witness plate that was hanging from the bottom of QUAD structure.
• We inspected the ETMx-HR - We saw no dead-ringer particle that was a more obvious "scatterer" than any other particles on the surface of the mirror.  We also did not see any large bits of left over FirstContact or other debris.  We put the green lantern onto the suspension structure and counted ~5-10 particles per sq. inch roughly everywhere in the central 8" circle area of the mirror - higher than what we counted on the ETMy.  We spent a few minutes blowing with the deionizing N2 Top Gun blower - not much moved.
• We decided we should FC clean the surface given that the particle count level was higher than the ETMy level, even though we did not find the one we were looking for.  We also noticed that more particulate was floating around in the flashlight beams than we noticed at ETMy.  See my particle count data below, though.
• Rick took quite a few pictures of the surface in an attempt to capture the particulate condition - pictures will be available tomorrow when we post final results.
• We clamped the optic with the TFE rail tooling.
• We applied brush-on FC in the same manner as yesterday (thick short dabs/strokes, 3 coats) and put the PETG cap on.
• WE wiped more of the floor.
• We removed all of the extra tooling/blow gun/lights from the chamber and exited for the day.

We will pull the FC sheet ~9:30 am tomorrow and hopefully get the door back on by lunch.

The Ops Overview screen that shows the graphic representation of the IFO (OPS_OVERVIEW_CUSTOM.adl) had been previously unable to report individual suspension stage watchdog trips. According to the models, the discreet watchdog stages are "ANDED" into an EPICS channel called $(IFO):SUS-$(LOC)_DACKILL_TRIG_STATE which was the only conditional channel included for the Visibility Calculation in MEDM. This channel will never show it's alarm state unless all upstream watchdogs have been tripped therefore making said "trips" invisible in this overview, which has become a popular one with operators and others as well (imo). Discreet watchdog channels have been added and tested for BS and all Quad suspensions. This overview screen can now be relied on  for accurate reporting on the status of any suspension watchdog trips.

Dan, Fil, Thomas

We made a quick modification to the ASC-AS_C transimpedance board today, so that the HAM6 fast shutter threshold can be set for 1W of light into the chamber.  The modification was a swap of R23, from 1.24k ohm to 422 ohm.  This changes the gain on the SUM_OUT channel on the back of the chassis, that's used for the fast shutter logic.

ASC-AS_C gets 2.5% of the light into HAM6, so we'd like to set the threshold at 25mW.  The input to the shutter controller rails at 2V.  The QPD transimpedance is 1000 ohms, the quantum efficiency is probably about 80%, and the new resistor changes the final gain stage to 422/4.99k = 0.0845.  So, the correct shutter threshold is 0.025*1000*0.8*0.0845 = 1.7 volts.

This modification only affects the signal path to the shutter controller; it doesn't change the signal path that is acquired by the ASC front end.  So the ASC-AS_C sum that you see on the MEDM screen hasn't changed.  (The input to the HAM6 shutter controller is recorded by the channel H1:SYS-MOTION_C_SHUTTER_G_TRIGGER_VOLTS.)

Evan, Alexa

Following the preparation described in alog 15524, we made a ringdown measurement of both the x- and y-arm. For each arm, we locked the IR beam and ran the wfs to ensure maximum build up. We then turned the wfs off, and switched the input polarity of the MC common mode board to unlock the MC quickly (based on LLO's alog 11727 the MC has about a 15usec ringdown time). We used the relfected signal at the AS port to capture the ringdown. We repeated this measurement 10 times to have ample data for our uncertainities. We also measured the "off-resonance" ringdown, by unlocking the arm and misaligning the respective ETM. All the data can be found in /ligo/home/alexan.staley/Public/Ringdown/EX(Y)data (these folders are then split into locked and unlocked times).  From this data we calculated the total loss:

X arm: 14310(100) ppm

Y arm: 15000(100) ppm

Based on the galaxy ITMY transmissivity (1.42%) this amounts to 800ppm of loss in the y-arm. Meanwhile, for the x-arm, the ITMX transmissivity is 1.39 % corresponding to a 410ppm loss in the arm. We are in the process of calculating the transmissivity of the ITMs based on our ringdown fit. Our code can be found in /ligo/home/alexan.staley/Public/Ringdown/proccess.py. The y-arm losses seems consitent with our scan measurements; however the x arm does not. These numbers are very sensitive to the transmissivity we use; so before we make an conclusion with this we should inprove our confidence in the transmissivity values.