R. Crouch, J. Oberling, B. Weaver, S. Appert

We are done with the surveying of the aLIGO BS on the mechanical test stand.  I'm still working on processing the data but can give a quick overview of where things stand:

• With respect to the ISI, the BS is within the aLIGO install specifications (lateral/vertical +/- 1.0 mm; longitudinal +/- 3.0 mm)
  • Position deviations when looking normal to the AR surface
    • Lateral: -0.7 mm (left)
    • Vertical: -0.8 mm (low)
    • Longitudinal: +1.8 mm (in the +X/+Y direction)
  • Will rotate these to the IFO coordinate system at a later date, once all data has been processed
• BS Pointing is NOT within the aLIGO install specification (Pitch +/- 55 µrad; Yaw +/- 190 µrad)
  • Signs reported using the standard SUS sign convention (positive pitch is down, positive yaw is CCW when looking top-down)
  • Pointing deviations from nominal (Pitch: -446 µrad; Yaw: +0.7849 rad (44.9699°) from the +Y axis)
    • Pitch: -200 µrad
    • Yaw: -710 µrad
  • The yaw deviation appears to have been counteracted by a CCW yaw shift done via HEPI once the BS was installed in WBSC2 back in 2013; no explanation for the pitch deviation, but I do recall that pitch did not hold very well on the journey from the test stand to the chamber back in 2013, so there's no guarantee that our measured pitch here is fully representative of the BS optic pitch from in-chamber
  • We have a suspiscion there is an error in the test stand monument used to do the pointing alignment back in 2013, and potentially an error in the LVEA monument used to the in-chamber pointing alignment; working out a way to test that with the FARO
• The BS SUS cage mostly hangs around the aLIGO position tolerances, but we never measured it during the 2013 install (as our target was to place the optic, and the cage ended up wherever it ended up), so this is the first data we have on its position

I'm working on a larger alog tying together all of our BS and WBSC2 measurements (WBSC2 support tube ends, BS in-chamber, and BS on the test stand) to provide a more complete picture of the BS alignment as we have measured it these last couple of weeks (it's going to be a long one); this alog will have the full set of data from the various test stand measurements.  In addition, the SUS and IAS teams met yesterday to discuss our path forward.  We decided that, despite the error seen in pointing on the test stand, we will align the BBS to its nominal position and pointing w.r.t. the ISI on the test stand.  Once back in-chamber we will use the BBS SUS cage position as the metric for adjusting HEPI to once again place the BBS in its nominal in-chamber position; pointing will be restored with the BS optical lever, as originally planned.  I'll write up a RODA documenting this decision and upload it to the DCC ASAP.

This completes LHO WP 13210.

Edit: Some spelling and grammar clean up.

TITLE: 05/08 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 4mph Gusts, 2mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.09 μm/s 
QUICK SUMMARY:

ISS Array work continues...MC2 troubleshooting continues.

I took a Met One  GT-521S laser particle counter into BSC2 to answer a few questions.

Q: What is the reading while standing still in the chamber? About zero

Q: How much dust will be suspended by reconnection of BS cables on the inside feedthroughs of BSC2?  A: I simulated reconnection of cables by tapping and wiping continuously in one of the nozzles for a minute and the 0.3um size value averaged about 200 particles/ cubic foot while the 0.5um size value averaged about 70 particles/ cubic foot. 

Q: What are the levels for walking around (gently) on the aluminum floor of BSC2? A: 0.3 um - about 150,  B: 0.5 um - about 80

Q: Does bumping the cloth cover over the top of the chamber increase dust levels? A: Less than walking on the floor

Q: What level is reached while wiping the floor? A: About the same as for walking on the floor.

Q: How long before the dust levels are difficult to distinguish from zero? A: For all of the above experiments, the readings were back to about zero after a minute or so.

Mitchell & Robert

Mitchell and I installed baffles on the +X side of HAM3 and we installed the scraper baffle extension on the -Y side of the scraper baffle. We also removed the lower central piece of the MC baffle near HAM3. Pictures of all of these are in the attached pdf. We are stopping now for a couple of weeks until the SPI baffles have been installed to avoid interference. When we get back to this, we will install the baffles on the -X side of the table, install the central scraper baffle extension, replace dog clamps on PR2 with shorter clamps so they dont glint, install a POP path baffle, and make final adjustments of the baffles using beam-spot photos. 

Ibrahim, Betsy

Today, Betsy and I set up a Dino-Lite to image the spots we found yesterday (alog 90147).

Below are photos including before and after cleaning - according to the names of the files. None of the spots seemed to change after cleaning.

We also cleaned the spot that's in the center (not imaged with dino-lite) but it also did not go away.

Current most likely hypothesis is a coating defect due to circular nature of the spots and the resistance to cleaning.

The corner RGA tree was rebuilt in order to match the standardized trees on other HAM chambers. This included reducing the amount of elbows and piping, removing calibrated leaks, installing a 10 l/s ion pump, and installing a full range gauge that can be read by the new PrismaPro RGA head. This volume will pump down over the weekend, and we will confirm the connection/functionality of the new RGA to the control room RGA computer. Once confirmed, the entire RGA tree will be baked at high temperature to clean the volume for use. The small area around the RGA tree (output tube on +X side) has been sectioned off with caution tape, please avoid the area.

TITLE: 05/07 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: The LVEA is now is laser hazard, HAM2 ISS swap and HAM3 cabling was started today.
LOG:

Jennie W, Jenne D, Keita K, Elenna C, Rahul K, Fil C, Jim W,

Summary: Today we started the replacement of the ISS array with its spare. JAC REFL PD was aligned and JAC locked but some problems encountered with MC2 which we need to fix so we can check the current ISS array alignment before removing it.

First part of day - JAC locking

• We had a bit of trouble locking the JAC till Keita reminded me to check the error signals. The beam needed aligned on the IOT1 table. Jenne and I did this with the two mirrors before REFL PD that are not common to the WFS path.
• After this we could lock JAC.

Checking beam in HAM2.

Checking the beam coming towards MC3 with the flashes transmitted back through the IMC, Keita and co realised that the IMC and input beam from the JAC were not well aligned.

Jenne and I consulted with Jim and isolated the HAM1 chamber, plus reset the set points for the HAM2 CPS. This means that the residuals for HAM1 were low but both HAM2 and 3 which have their ISIs locked, are out of nominal alignment, ie. higher in pitch and lower in yaw than their nominal.

The positions we want for MC2 to put  compensate for the ISI relative alignment change are M1-OPTICALIGN_OFFSEt_P = 864/858

M1-OPTICALIGN_OFFSET_Y = -451.5/-354.5

The positions we want for MC3 are M1-OPTICALIGN_OFFSEt_P = 417

M1-OPTICALIGN_OFFSET_Y = -185.4/-190.6

The positions we want for MC1 are M1-OPTICALIGN_OFFSEt_P = -686

M1-OPTICALIGN_OFFSET_Y = 1352/1358

Unfonrtunately while trying to align MC2 we encountered some problems with the suspension so that is in the process of being debugged. Possible culprit is the D6 feedthrough swap last Thursday on HAM3 as MC2 top mass osems changed a lot that day. Left record of values we need to align osems to above so we can come back to this when we have fixed MC2 problems.

ISS Array

In the meantime Keita, Rahul and Elenna opened the box with the new ISS unit in the clean room and prepared to swap out the base with the one in chamber (our new unit is set for L1 beam height). To do this thye had to removed the blue glass beam dumps to reach the 1/4-20 screws at the four corners of the middle ISS mounting plate.

(Jordan V., Dave B., Gerardo M.)

The internal pressure to CP1 turned around overnight signaling that the process of emptying the trap is complete, now we'll continue to monitor and pump on the cryotrap volume.until good pressure is achieved.

A side note, I manually turned off the CC for PT114B last night at 9:44 pm (local time) as the pressure was rising a bit high, then turned it back on this morning at 5:33 am local time.

Attached is a snapshot of one day trend data of pressure behavior regarding the soft regeneration for CP1.

Process started here.

TITLE: 05/07 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 5mph Gusts, 2mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.26 μm/s 
QUICK SUMMARY:

• Temps looks good, no dust alarms
• Potential LVEA laser hazard transition today to allow
  • ISS swap
  • JAC locking and WFS work
  • SQZT7 table beam profiling

The baffle on the +Y, +X wall of HAM2 has to be moved in order to enter the MC tube from the +Y door of HAM2. I readjusted it after it was moved, but, in case I am not around, the important thing is that it stick out about 2 cm from the tube wall. This means that the upper and lower corners of the baffle stick out past the wall of the beam tube just a tiny bit. I attach the photo from the original log, 75688, to demonstrate this. 

Ibrahim, Betsy, Rahul

First contact was successfully poured on BBS01 AR side. Pictures below.

Ibrahim, Betsy, Rahul, GariLynn

Following AR side first contact removal, we did our first flashlight inspection of the AR side (S2) of the optic. We found that there were 4 spots of varying size all under 1mm, perfectly circular. They seem to look like water (look at image). We contacting COC (GariLynn), who informed us this may be some coating defect. Nontheless, we tried cleaning it.

There are 2 smaller spots on the side of the optic (see image). There are 2 other spots near the center, with one being pretty dead on-center.

First, we used acetone with a cotton swab to wet two spots (the ones on the side). This didn't work and the spots were still there.

Second, we followed T1800350 to clean two spots with water, then immediately apply first contact. This didn't work either.

We will continue to clean spots with water tomorrow. Images below.