Krishna, Sheila, Hugh, Fabrice:

We have been chasing  large amplifications at low frequencies (in the range of 10mHz to 30mHz) caused by the Z zensor correction of HEPI, which is necessary to reduce the Z to RZ coupling on Stage 1. It looks like the Z HEPI inertial isolation is causing rotations (RX, RY), that are causing tilt signal in the Stage 1 horizontal seismometers, that couple to X and Y as we blend at 45 mHZ, and then shows up into the cavity signal.

The problem was mostly  visible on the BS unit.  We convinced ourself that Z to tilt  was the problem by moving Stage 1 in high blend, which very significantly reduced the Mich amplification around 20 mHz (which exist only when the Z sensor correction is ON)

It seems that the excessive Z to tilt coupling in the BS was caused by off centered  vertical position sensors (up to 24000counts). We recentered them by applying  a HEPI vertical force. The Z to Mich coupling is now much lower. So I guess that the gain of the sensors was affected by the large offsets and thus creating excessive Z to RX and RY couplings.

Comparison with high blend configurations show that there is probably room to further reduce this coupling. We need the measure the Z to RX and RY coupling and apply corrections.

Dave, Jim

To perform some further HWWD testing at ETMY, we have temporarily connected the HWWD RMS analog monitor (BNC output on rear of unit) to a spare PEM channel on its AA chassis. We are reading the channel using the slow IOP DAQ channel. The plot shows 1 minute of full 16Hz data during the recent ETMY in-chamber work. The 1.6 second integration time can be easily seen in the data.

We are using the next to last channel on the PEM AA chassis, this is ADC3, Ch30 (counting from zero).

Recent in-chamber work on ETMY has provided a OSEM PD RMS trip level comparison between the Hardware watchdog (HWWD) and the IOP software watchdog (SWWD).

We have verified that the two systems have very similar trip levels. The SWWD trip level is hardcoded at 110mV. The HWWD level can be modified, but it is running at its default of 110mV.

The plot shows: the PD RMS status for the SWWD (Ch 4, GOOD=1, BAD=0); and the HWWD (Ch 2, GOOD=0, BAD=1). Also shown is the SWWD RMS monitor for the ETMY top stage OSEM, SIDE channel, which is the channel driving the RMS errors.

As can be seen, Ch4 and Ch 2 match each other very well.

Note that the maximum time in error in this plot is only 3 minutes. If the excitation were to extend to 10 minutes the SWWD would have tripped the SEI DACs, and if it were to extend to 20 minutes the HWWD would power down the ISI coil drivers.

Approved work to be done:

1.   Cleaning and assessment of ETMY HR surface
2.   Replacement of EY ESD vacuum feethrough connector assembly
3.   P-Cal alignment

Thursday, Dec. 11

• 1st cleaning of BSC10
• Move Clean Room (CR) into position for BSC10
• Vacuum rooftop of Clean Room
• Attach sock
• Start collecting supplies: FC, solvents (acetone), Green Lantern, Flashlights, PET contamination kit, ...

Friday, Dec 12

• 2nd cleaning BSC10
• Turn on purge air for BSC10
• Make sure CR supplies are in place (gowns, change room, ...)

Monday, Dec 15

• Dust Monitors - verify operation
• make safe.snap files to save settings
• Follow M1300464-v4, "Procedure for preparing aLIGO IFO for pumpdown", Turn off high voltage
• Review and follow E1201035, "aLIGO Chamber Entry & Exit Procedures" checklist
• Review and follow M1100068-v1, "Hanford Checklist - BSC Door Removal", Review door removal procedure with crew
• AM
  • Start vent on BSC10, estimate ~5 hours [Kyle and John]
• PM - follow E1201035
  • Lock down HEPI
  • Wipe down cleaning to ensure area is clean
  • Remove door
  • Document (photograph) entrance and assess for obstructions (hanging cables, loose wires, ...)
  • Enter and secure ISI and SUS
  • Follow E1400472-v3, "Test Mass In Situ Cleaning Procedure", continue on to Tuesday, Dec. 16. Note that First Contact cleaning is preferred and drag wiping is only to be used as a last resort (see procedure and flow chart in E1400472-v3). The only approved solvent for this cleaning work is acetone.

• ESD Connector Repair

After Chamber Vent Following E1400430
1: Disconnect external (air side) ESD cable from feed thru.
2: Install flat surface with Vacuum Foil on it near Flange for a work
surface.
3: Remove ESD feed thru flange  Gerardo
4: IF enough cable exist cut the cables from the connector on the inside.
    IF not enough cable disconnect cable
    disassemble connector then remove connector ends.
5: Crimp new pin on to cables.
6: Verify with SUS which pin is connected to which part of ESD.
7: Make up connector with new pins in proper order D1400177 V2
8: Secure new connector to new feed thru.
9: Install Flange on Vacuum chamber.  Gerardo
10: Connect new external cabling to feed thru
11: Ensure no one is near optic!!!  High Pot connector ~ 700V DC  If it
doesn't pass.  Stop and investigate.
12: Make up external cables to field current limiting resistor box.

Tuesday, Dec. 16

• AM
  • Continue with ETMY cleaning as described in E1400472-v3. Note that First Contact cleaning is preferred and drag wiping is only to be used as a last resort (see procedure E070304 for drag wiping). The only approved solvent for this cleaning work is acetone.
  • Meet with SYS and COC team members to assess.
• PM
  • Perform spot cleaning on edge in attempt to understand First Contact edge contamination ring.
  • Apply 2nd round of First Contact, cover, and allow to dry and cure over night.

Wednesday, Dec. 17

• AM
  • Peel First Contact and assess the situation with SYS and COC
• PM
  • Prepare to close WBSC10 EY as per  E1201035, "aLIGO Chamber Entry & Exit Procedures" checklist
  • Review and follow M1100068-v1, "Hanford Checklist - BSC Door Removal"
  • Unlock ISI and Optic
  • Verify optic is free
  • Assuming all goes well, obtain approval and signatures for volume closure (M1300172).
  • Notify door crew to hang door
  • Verify readiness to pump down, follow M1300464-v4, "Procedure for preparing aLIGO IFO for pumpdown". Confirm all high voltages are off.
  • Notify Vacuum crew of readiness to start pumps

The last step is at the time and discretion of the Vacuum crew.

Took dust monitor trends from End-X ahead of the vent. Posted are a 7 day trend for both location #1 and #2 and a 72 hour trend. The first cleaning and cleanroom over BSC9 were turned on 12/16/14. 

Here is an estimate of the BRDF for ETMx and ETMy from the recent scattering images we took. 

BRDF=Ps/solidAngle/Pinc/cos(theta_s), in W/steradian , as quoted by Hunter Rew in P1400197.  Ps is power incident on photodiode, solidAngle is that subtended by the photodiode, Pinc=incident power (here the IR power inside the arm), and theta_s is the scattering angle, which is the angle of the photodiode from normal incidence.  SolidAngle-A/L where A is the area of the photo diode and L is its distance from the test mass.

Ps=calibration_factor*Intensity/Exposure, where calibration factor is in (W*microseconds/counts) and is defined by David Feldbaum in LLO alog 12627, intensity is the total pixel counts on the CCD, and exposure is the camera exposure in microseconds.

Pinc is calculated using Dan's calibration of the TMS photodiodes outlined in alog 15431.

A is as given by the camera specs = 1.0209e-05 m^2.

Rick Savage and Joe Gleason helped me get the distance and scattering angle of the camera from the mirror.  L is 6.0452m and theta_s is 4 deg for the ETMS. .

The other paramters used are:

Because these images are taken at small angles, its not valid to assume the BRDF is constant, so its not meaningful to integrate the BRDF to get an estimate on total scatter in ppm. I wanted to compare numbers to the ITMs, however I can't because the analogue gain setting was different (1023 not 100) for the ITM pictures.  Once ETMy is clean and we have the Y-arm back I will re-measure ETMy and also add numbers for the ITMs.

ITM03 - had a full sheet of FC applied with NO IAS windows, see attached.  ITM03 was installed in BSC3.

Thomas V, Elli

The ITMy and ITMx Hartmann wavefront sensors are now aligned to their respective SLEDS.

We took the HWS plates out and centered the SLED beam on the camera using the periscope mirrors and the final mirror before the HWS (pictures of the final alignment on the camera are included).

The ITMx image is a lot dimmer than the ITMy image, however the H1:TCS-ITMX_HWS_SLEDPOWERMON  said 5mW whereas H1:TCS-ITMY_HWS_SLEDPOWERMON says 1.8 mW.  We were watching to maximise image brightness as we made the adjustments so I don't know why ITMx image is so much dimmer.

This morning, travis and I pulled the FC sheet that we applied to the ETMy yesterday.  The patchy smudge mark and the large gooeyish particle that we induced yesterday were apparently picked up by this FC sheet.  While there, we tested using the cotton tipped Q-tip on a portion of the ring around the edge of the optic (~1Inch in from bevel edge near the bottom).  We used both DI water and also acetone, both chased with ~5 spot drag wiped of acetone using the pressure technique.  Upon evaluating neither q-tip+ acetone drags seemed to improve the area since both swipes added to the streaking which the chasing acetone could not fully remove with 5 wipes.

End-Y: The faulty ETM-Y ESD connector was repaired (see aLOG #15656).   
The first cleaning of the ETM-Y optic with First Contact was completed with some success. There are still several areas of concern left on the optic. A second First Contact application will be removed today. 

End-X: Preparations (cleaning, cleanrooms, garb, etc.) for entry into End-X are underway in case it is decided to clean the End-X optics.
    
HAM1: The work in HAM1 is finished. The door will be reinstalled today.

EE: PEM cabling work in the LVEA.

Seismic: Hugh adding CPS ground straps to the HAMs in the LVEA. 

Betsy, Travis, Rick

How today went:

We spent a few hours this morning working on the in-vac side of the new ESD connector termination checkouts. 

At ~2pm we pulled the FC sheet off of the ETMy-HR (painted on last night).  We immediately saw that the 3 larger FC remnants that were causing all of the glint in the cavity arm were removed.  Yay!  However, it was also immediately clear (with the green flashlight) that the 3" ring feature and mottled haze were still there. 

We took a break at 3pm and spoke to a wider SYS+ audience where it was determined we would attempt to do a test drag wipe on the mottling nearer the edge of the optic.  We worked on getting pictures of numerous mottled areas in the haze of the donut shape on the ETMy-HR before doing some test drag wipes.  Then we chose an area toward the top of the optic where there was another relic IAS window circle print near the 12 o'clock position to test drag wiping.  After numerous failed attempts at performing the light-duty friction-only drag wiping technique on this area I resorted to folding the lens wipe a few times and applying pressure during the drag wipe.  This made a smudge where I wiped which I then had to spend another ~5 wipes removing.  We then reevaluated the mottling and found that we might have improved it in one small place, but not the entire area I had been working on.  We then redirected a streaky area at the bottom of the optic to see if I could get a better technique down.  No such luck and I again had to resort to applying pressure numerous times in order to see an improvement.  Since we had better pictures of the 12 o'clock position mottling area that I had been working on earlier, we decided to revisit that area.  I again made an attempt at friction-only drag wiping of this top area.  In the process I must have lightly swiped the optic with my glove because when inspecting the optic after the drag wipe, we found a ~2mmx2mm patch of particulate just outside of the 3" ring near the center of the optic.  Brilliant.  We also found more particulate on the optic from the waving lens tissues.  We tried to blow them off with a few minutes of N2.  This did not seem to work.  One of the particles was quite large and even a light dab with an swab did not move it (in fact, ~5 attempts to snatch it off via dabbing failed).  Rick captured a few pictures of the "new" features.

At this point we aborted the drag wipe testing and carefully repainted FC back on.  I was very careful to not brush across the large particle nor the "patch" area very much.  I applied very thick ~1 inch long strokes which at first were more like dabs near these areas.  (All other saturated sloppy strokes were ~1-2" in length, repeated.)

I do not think we can drag wipe the full surface (or even the central ~8") of the ETMy-HR.  We were not sucessful in ~25 attempts to get a good pull on the optic except for in the localized areas I mentioned above when I used finger pressue.  And after these attempts we added contaminant to the surface by accident.

The optic size obviously makes it hard to work with.  The working area is too small for 2 hands, elbows, flashlights, your head, etc.  Then, the task is too hampered by suspension brackets and braces to get good surface tension with the flat lens tissue.  The wipe wants to continue to pull off the surface and ripples easily.  As well (or worse), we had a hard time getting the wetted wipe to the surface before the acetone dried.

Rick plans to attach some pictures to this alog so check back later or tommorrow.

[Mackenzie, Paul]

Yesterday we had trouble getting a large enough beat signal between the aux laser and the main PSL. After discussions with Dave O., Stefan and Daniel, we were convinced that the aux laser was not operating monochromatically. This can apparently occur if the aux laser is close to a "mode hop" region when we bring its frequency close to the PSL frequency using the temperature control. We then end up observing the beat frequency between the PSL and one of the "parasitic" modes of the aux laser, which has a much smaller amplitude than the main mode.

On Daniel's advice, we adjusted the diode input current as well as temperature, in order to give us an additional frequency control option that affected the proximity to the mode hopping region differently to the temperature. After some searching around, we suddenly observed a forest of peaks, with one especially large peak.

This forest appears to have been a combination of a) saturation of the 1811 AC output exciting harmonics of the base beat frequency and b) contributions from RF sidebands of the PSL light. We reduced the power on the 1811 using the filter wheel (we ended up using the OD 2.5 filter), resulting in the spectrum shown in the attached figure. The VCO offset frequency was 20MHz. Interestingly, the beat between aux laser and 9, 45MHz sidebands are quite visible.

The dominant beat frequency now registers a -22dBm signal at the AC PD output on the spectrum analyzer, even with the power on the PD attenuated such that the DC output from the PD produced by the PSL beam is less than 1mV (the PSL beam is the weaker of the two beams at the PD). This may still seem a little weak, but it is much better than yesterday, when we had ~-50dBm AC on a ~100mV DC signal.

After some adjustment of the servo box gains, we were able to achieve stable PLL locks. There is no slow temperature servo path included yet, so the PZT on the aux laser will go out of range rapidly if the temperature dial is not adjusted by hand. By adjusting the temperature dial, it was possible to keep the PLL locked for tens of minutes. 

Next, we switched the frequency reference for the PLL offset from the Marconi VCO to the swept sine output of the network analyzer. This presents a new challenge, because now not only does the aux laser have to phase lock to the PSL, but it also has to track the offset frequency generated by the NA. After playing around with IF BW, sweep ranges, source power etc., we were eventually able to get the aux laser to reliably phase lock to the PSL and track the NA frequency through a ~2MHz frequency range (almost enough for a full PRC sweep). We convinced ourselves that the PLL was locked and tracking the NA frequency by observing the TF from NA drive signal to 1811 AC output. When the PLL is locked, the TF is flat, high, and smooth, since the 1811 AC output is coherent with the NA signal at the same frequency. When the PLL is unlocked, the same TF is many decades smaller.

Each time the NA reaches the end of a sweep and flips back to the start frequency, the lock drops. I'm not sure there's much we can do about that. It would help to have the slow path enabled though, in order to compensate for slow drifts of the aux laser frequency away from the PSL frequency. 

Next we plan to try some PRC sweeps if there is PRMI locked time available. For this, we will take the TF from NA drive signal to one of the REFL AIR broadband detectors, with the PRMI locked and the PLL locked. Depending on how that goes, we may pursue the slow temperature feedback development.