After testing a known good channel on it, we determined that channel 3 of AA2 is bad. 

[Stefan, Kiwamu]

  Today Stefan reminded me that the WFS RTS library parts for its DC signal was updated in July 30th (see LLO alog 8061) and we haven't applied it at all in LHO. This update was for fixing the numbering of the four DC segments to match with that of the RF segments. Before appplying this updates, we wanted to make sure that this is the right thing to do. So for the reason we did a brief check on the existing WFSs, namely IMC WFSs on ITO2L. We intentionally misaligned the IMC REFL such that it hits only one of the four segments and did a block-and-unblock power modulation by hand to identify which segment responds. We went through all four segments on both WFS_A and WFS_B. Indeed the DC segments were in a wrong order of {4,3,2,1} while it is {1,2,3,4} in the RF segments. Indeed we need to correct it in the IMC realitme model although we haven't corrected it yet.

 Looking at the l1asc model which uses the updated WFS library, we noticed that the labels of the tags associated with the DC library parts were incorrect. We probably need to talk to poeple in LLO to make sure that the update was done in a proper way.

VBO A is up and running again but the side effect is really high dust counts in the optic lab's vacuum oven room. For now the door to that room is closed, but hopefully the counts will drop soon. The fiberglass heat tape and insulation are the largest culprits.

We've tested a new tripod mounting system for the magnetometers with aims to decrease artifacts from motion of the magnetometer on the tripod. The iLIGO mounting scheme resulted in peaks in the magnetometer spectra that were not from real magnetic fields but from the magnetometer moving in the earth's field at tripod resonances. We tap tested both tripods to study their resonances and damping. The flagpole resonance of the current tripod is at 7.9 Hz. The new system, designed at Cal State Fullerton, is more damped and rigid. 

Attached is the power spectrum of both setups, side to side (see photo). The red trace is the magnetometer mounted on the current tripod, the blue trace is the magnetometer mounted on the Fullerton prototype tripod. The flagpole resonance of current tripod is seen at 7.9 Hz, the one place the blue Fullerton trace does not follow. Most other peaks seen are from nearby cleanroom fans and the expected 60 Hz. 

Terra, Robert

TMS ISC cables were attached to the mass using metal clamp with kapton tubing.

Took longer than we first thought because we had an interference with the screw tip of the clamp and the side of the blade, and had to experiment with shimming. Too thin a shim and your screw protrude more from the back and interfere with the blade. Too thick and your screw doesn't go all the way through the threaded hole of the bracket, and the thickness of the bracket seems to be smaller than 1/8, much thinner than you would  expect from 1/4-20 thread.

Then the cables were attached to the cube rather than the ceiling using peek clamps. This is because we don't have a good tapped hole to mount cable clamps under Bosch frame. Once it is moved to the test end we'd have more options, but in the mean time this should be good.

The top mass was rebalanced, table cloth was readjusted to maximize the clearance (the tolerance is extremely tight), BOSEMs were repositioned but we couldn't proceed as there was a trouble attaching the side BOSEM to the new mounting plate (see another alog).

In parallel with side BOSEM effort, we still need to mount the dummy feed through to the Bosch frame, put the BOSEM cables on, and set the height of the BOSEMs correctly, which looks like half day's work, before we can test the SUS.

Side BOSEM mounting plate that came out of the oven today didn't have tapped holes and we couldn't mount BOSEM on it.

According to https://dcc.ligo.org/d060323 it has four 8-32 tapped holes, looks as if the shop just drilled holes for the tap and then forgot tapping.

Will talk to Bubba and Tylor to see if they can dry tap (we need four such holes per plate). No SUS test today.

Robert reported ADC issues with the PEM model in the corner station. I restarted the h1peml0 and h1iopoaf0 models and he reports the problem has been resolved.

I re-imported the l1asc.mdl to Hanford and compiled it.

Changes:
 - L1->H1 globally
 - l1 to h1 globally
 - LLO to LHO globally
 - replaced the PSL IPC with a simple epics input (temporary, due to missing hardware).

Recompiling and running worked, but revealed a bug in the RTCDS code:
 - the kill script got stuck in the burt safe command. Temporary fix: replace grep h1asc with grep "h1asc "

Next I will start adding the inital alignment stuff for the arms.

Had to restart these to restore communications.

- Works at EY
    Apollo: ask Bubba
    Richard ask him

- Works at EX
    Keita (ISI) getting ready for SUS

- Works at LVEA
    Michael, Hugh: ... some HAM are offset by several mm and that can cause problems with the mode matching ... (talk to them)
    Arnaud TF

- Michael gave a tour to a PNNL group
- PRAXAIR came around 9:30AM, left around 11:40AM
- (14:20) John and a group of contractors went to the roof
- Mark Hankel and the fire department were checking fire extinguishers
- DUST at Bake-Out was very high (15000 for 300nm, 5000 for 500nm) today. Patrick told me that Greg was working inside. John is aware of the situation.

Attached are plots of dust counts requested from 4 PM August 13 to 4 PM August 14.

Terra Hardwick, Vinny Roma, Robert, Stefan)

We hat 2 accelerometers mounted on the two pryramid-shaped periscopes on ISCT1 that are in the ALS beam path.

Below are plots of the velocity spectra for each accelerometer, as well as for the difference. No separate calibration was applied - we simply took the difference of the raw data. However, as can be seen from plot 3, the two accelerometers seem to be matched to better than 1%.

Plot 1 shows the of periscope 1 vs periscope 2 spectra. Note that the highest peak is just below 70Hz, but common in both periscopes - the two periscopes seem to be locked together. The peak just above 70Hz however is the dominant one in the difference spectrum. It is also the one that shows up in the HIFOY spectra.

Plot 2 shows the two accelerometers mounted on the same periscope (the middle one that carries the green beam from x and y arm). The accelerometers were mounted at a slightly different height, about a 3 inch appart, corresponding to a setup with different mirrors mounted on top of the periscope. Note that we get about a factor of 10 suppression.

Plot 3 again has both accelerometers mounted on the middle periscope, but at the same height, i.e. simulating a situation with all three beams hitting the same top periscope mirror. The suppression factor is now too good to believe. This suggests that if possible, using the same top mirror for all 3 beams would be beneficial.

One warning about the accelerometer mounting: they were attached directly to the periscope. having two different mirror mounts can make the situation slightly worse. This again would suggest that using a single top mirror would help.

All plorts are calibrated in m/sec/rtHz.


 

Spent an hour to play with the cable clamp bracket, and improved on Cheryl's idea to use metal clamps with kapton tubings (first picture).

One D1000921 (thicker, for pico, beam diverters) and one D1000921 (thinner, for QPDs) are wrapped with kapton tubing and clamped using a pair of metal hold down clamps (second picture). Two such pairs are made (third picture) and they sit next to each other. I also tried making thin-thin and thick-thick pair, but it didn't work well. Thin--thin is easy to rotate between the clamps and goes to "bad" position in the first picture easily, losing any clamping pressure.

Extra care should be taken to align things properly, and the number of washers should be chosen such that everything is snug but not too tight when the bolts are tightened. When you pull the cable it should slide inside the tubing, but it should not slide on its own.

With too few washers, it's easy to put too much pressure on the cables which promotes short circuits as the soft teflon insulation is broken. With too many washers, even if it feels OK at first, it is easy to rotate the cables in the clamps so the cable pair goes to "this is bad" position in the first attachment and the thinner cable becomes loose.

Note that I'm abusing a 1/4-20 aluminum nut as a poor man's washer. This is because the normal washers we have is too big and interferes with the curved  part of the metal clamps, and we have a limited supply of smaller washers. It's working OK, when I tightened the bolts there's no loose thing.

This is just a test run by one person using the wrong end of the cables for ease of access, we'll do the real run tomorrow.

Dan worked on the MSR SATABOY and its associated Sun/Oracle server. He upgraded all firmware and moved hardware around. The disk system is back online and no data was lost.

We have restarted h1fw1 and h1nds1 and frames are being written again. The data gap on h1fw0 is

aug 13 23:31

aug 14 17:04

This afternoon Jim moved the default NDS from h1nds1 to h1nds0. We will keep it this way overnight and swap back tomorrow if h1fw1 continues to be stable.

Out of the 4 DoF (arm optical axis pos and angle, green input beam pos and angle, 2x for pitch and yaw not counted), 3 DoF will likely need a frequent initial alignment - the input beam position at the ETM is the one DoF that remains fixed.

Below is a short description of the suggested alignment loops. Attached is a draft RTCDS model block for e.g. X-arm pitch (we need 4 of them for X/Y P/Y).

Signals to be demodulated:
L: cavity PDH length error signal (green)
R: cavity reflected power (green)
T: cavity transmitted power (green)

Actuation basis (in rad):
(ITM, ETM, TMS)

g-factors:
g1=1-L/R1;
R1= RoC of ITM
g2=1-L/R2;
R2= RoC of ETM

Dither drive frequencies:
f1: ITM dither frequency
fT: TMS dither frequency

Control loops:
1) Fix ITM actuation node
L --->x ---> CTRL_FILT -----> (g1,1,1)
      ^
      |
      f1

Remark:
- Actuation at 1.65-2Hz or above 4Hz seems possible in pitch
- Pitch centering offset at 1.7Hz: ~2.3mm (slightly freq. dependent)
- Pitch centering offset above 4Hz: ~4.7mm
- Could provide a slight additional length drive to compensate this offset
- no such issues for yaw
- Actuation leaves the following quantities unchanged:
  - arm axis position on ETM
  - angle between arm axis and input beam


2) Input beam to arm axis angle overlap at ETM focal point
R or T ---> x ---> CTRL_FILT -----> (1,g2,g2)
            ^
            |
            f1
Remark:
- Actuation leaves the following quantities unchanged:
  - arm axis position on ITM
  - arm axis to input beam separation at ETM focal point
  - input beam position at ETM (trivial)

3) Input beam to arm axis angle overlap at ETM
R or T ----> x ---> CTRL_FILT ----->  (0,0,1)
             ^
             |
             fT
Remark:
- Actuation leaves the following quantities unchanged:
  - arm axis position and angle
  - input beam position at ETM (trivial)

Alternatives:
- GigE camera centering on ITM (instead of 1)
- ETM dither possible, but due to the steep drop-off of the Quad actuation, I expect reasonable drive amplitudes (producing a decent dip in power buildup) to only be possible at very low frequencies. As a result, since the dither frequency separation dictates the achievable bandwidth, it might be difficult to run all dither loops at the same time.

General Remarks:
- The dither drive is done in the optics basis, because any other basis would require significant attention to the relative phase of different actuation functions.
- To be able to run the loops in sequence, an orthogonal actuation function is desirable.
- repeat procedure of X- and Y -arm, pitch and yaw
- Once both arms are aligned, turn this feed-back off.

Kyle, Gerardo 

Today, after John had notified Rai of our intent, we applied a few drops of Vacseal (SPI Supplies, Space Environment Laboratories, original formula 0502-AB) to the top of the previously identified leaking 1.33 CFF on GV6 (North gate annulus port).  The leak seams to be fixed now.