PeterK and RickS

Today we used the Agilent RF analyzer to investigate the FSS OLTF.  We tried to make this measurement from outside the LAE, but found that the necessary cables (In1, In2, Test2 in) were not run from the TTFSS to the field box.
We found that the common gain (and likely FAST gain) sliders were not able to take advantage of the full range of the AD602 variable gain stages.  The conversion from slider units (0 to 1) to gain (-6 to 24 dB) is 0.031 slider units per dB with 0.5 slider units corresponding to 10 dB.  It seems that the channel is set up to give +,- 500 mV range and the AD602 needs +,- 625 mV to give the full -10 to 30 dB range.

We adjusted the half wave plate for the RefCav path to 190 on the dial to give more power such that we could achieve the desired UGF (to take advantage of the phase bubble) of about 450 kHz where we have about 52 deg. of phase margin (see attached plot, not that the UGF is at -10 dB on this plot).  The Common/FAST gains are 0.969/0.930.

After adjusting the gains, the Lock Acquisitions counter is at 277 when we left the LAE.

Summary: Photos show arm cavity baffle installation and the view of the baffle from the ITM and ETM. Part of a reflective bellows can be seen from the test mass through the H1 hole. I include a photo of the interior baffle surface that could be used as a dust witness plate near the test mass. Particle counts measured during installation did not exceed 100/ft^3 (>=0.5um).

Installation photos:

Figure 1 is an annotated selection of installation photos that Lisa A. took.

Glint search:

Figures 2 and 3 show photos taken to look for potential retro-reflections  - in particular, to find surfaces that reflect light scattered from the beam spot on one of the test masses back to the beam spot. This retro-reflection, and reflection to the beam spot on the opposite test mass, are thought to be the dominant paths for scattered light noise. For the side of the baffle viewed by the ETM beam spot, Figure 2, the camera and flash were set up in the beam path many meters from the baffle. The brightest retro-reflections from within the clear aperture were from the diodes and their mounting screws and from the edges of the bends in the baffle.

For the ITM side of the baffle (wide-angle scattering side), Figure 3, I placed the camera at the location of the beam spot on the test mass, except that I had to use the side that didn’t have an optic. The baffle is close to symmetrical so I believe that the actual beam spot would have a similar view of retro-reflections from the inside of the baffle. The brightest retro-reflectors (at least at visible wavelengths) are the backs of the photodiodes, screw heads, and the bellows on the spool between the manifold and BSC8, which can be seen through the hole on the opposite side of the baffle. The outside of this bellows would be a good place to mount a shaker to test for scattering problems. It would be possible to block the view of this bellows with a divider between the two sides of the baffle.

Contamination control:

The large equipment was first staged in the Y-manifold while the dam was located in the spool piece, separating cleaned BSC8 from the un-cleaned manifold. I had recently found that particle levels were ten times higher in the manifold than in BSC8 for similar activity levels, here, and wanted to use the dam to keep manifold activities from contaminating BSC8 and the ITM. Immediately after transport, I measured particle levels in the manifold next to the dam to be about 1000/ft^3 (0.5 um or larger). After the particle level reached about 150/ft^3 (~20 minutes of sitting), I removed the dam and left carefully. As I was leaving, I measured the particle level at about 200/ft^3.  

For our work in BSC8, we had to walk a short distance into the manifold to retrieve the staged equipment, so I wanted to have clean air flowing out of  BSC8 into the manifold (clean to dirty) rather than the other way around. I made sure that the clean room at BSC8 would overpower the clean room at the spool piece, where the Y manifold was open, driving air into BSC8 from its clean room and down the manifold to the opening at the spool. To do this, I turned off the purge air, had the C3 removed from over the BSC8 ISI, removed the C3 from the manifold opening and pulled aside some of the clean room curtains there to reduce pressure in the clean room at the spool. Previous experiments had shown that this produced a good air flow from BSC8 into the manifold and out at the spool.  Most of the air was coming in through the BSC8 dome opening so I checked the particulate level, finding under 50/ft^3 inside BSC8, even when a person was on the upper level working on the ISI.

Immediately after installation we carried the railing down the manifold, and I measured particle levels of about 50/ft^3 in BSC8 as Art walked down the manifold.

Figure 4 is a photo of the inside bottom surface of the baffle, showing a few dust particles. This surface is quite close to the test mass and may be a good witness plate to monitor accumulation of dust. I think we should photograph it again when we button up.

Robert S., Lisa A., Scott S., Art R., Manuel R., Thomas V., Jodi F., Chris K.

(Doug, Travis, Hugh, Annamaria, Jason)

The final pointing is PITCH ~ 9uradians to the required beam line
                      Yaw ~ 10 uradians to the required beam line

Having the Cartridge alignments and the GAP/parallel alignments accuracies close was very useful as the laser collimator return reflection was swinging through when the optic was released from the EQ stops.

Tightening the setscrews on the pitch adjuster screws influenced the pitch pointing by ~ 150 uradians.

Care must be taken to determine the HR reflection from the AR reflection.

One full turn of the sus pitch adjuster = about 400urads of pitch change.

1/4 turn of the static ISI adjusters = about 240 urads. This was done by tightening one sid and loosening the opposite and working through the 8 adjusters.

The arm cavity baffle alignment visually as seen through the theodolite is well centered. The baffle apurature is not perfectly round and so I averaged the gap about the ITMy. Previous measurements from the corner cube gave us a quantitative number for its location. The pusher assembly needs to be removed yet.

In the end all went well, but patience is needed and damping ring down takes 15 minutes or so to see the readout.

We installed the H1 PSL table using our standard epoxy float technique here. The plot shows a comparison of the H1 table to the H2 table, installed in the spring. The lowest resonant frequencies are about where we want them.

Robert S., Rick S., Michael R., Bubba G.

A. Effler, G. Moreno, T. Sadecki

After yesterday's reapplication of First Contact on the ready-to-be-attached ETMy reaction chain, I peeled the new FC from the AR face of the ETM and cleaned up the edges with acetone.  Satisfied with the cleaner appearance, we began the delicate process of mounting the reaction chain next to the main chain on the upper structure.  With the assistance of the highly useful 5-axis table, and the keen eyes of Gerardo and Anamaria, the mating went smoothly.  Due to adverse weather, we decided that this is as far as the ETMy would progress today.  Currently it is attached to the US, but the wires between the Top Mass and the UIM still need to be attached in order to begin assessing alignment.  Also, the AOSEMs in the PenRe were removed to facilitate the mating by reducing interference with the flags, so these will need to be reinstalled and aligned before hanging the chain.  All in all, BSC6 is progressing, albeit slower than anticipated due to ongoing work on BSC8, travel of the installation team, and, now, weather.

Note: In spite of an attempt to locate the 'old-style' non-captive lower structure spacers, we wound up with one of the 'new-style' captive spacers with a non-captive, i.e. fully threaded, screw out of the 8 total spacers required.  We decided to see if it would work, and in so doing, decided to put in in the least intrusive place (the lowest, right hand position; it can be identified by looking at the backside of the screw opposite the head since we used a 2" spherical tip EQ stop screw) in case we desire to replace it in the future.  With a little help from a pair of needlenose pliers, we were satisfied that we were able to get it sufficiently tight.  Captive hardware for these is being ordered ASAP.

JimW MitchellR GregG Hugh

Greg & Mitchell Locked the ISI & used the crane to lift the four 150lb Keel Mass Stacks and placed eight 1x1x1/4"thk viton pads, two under each corner of the stack.

Meanwhile, Jim & I unbolted the six Optical Table Mass Stacks and replaced all the viton with approved material.  We also added a second metal washer under the shoulder of the Shoulder Screw to compress the viton a little less.  Now we'll see how those peaks look.

Since the ACB needs a little more tweking, we left the ISI locked.  HEPI remains unlocked.

As IAS told us last night we were 0.4mm South, we disconnected the Vertical Actuators and then based on the Dial Indicators moved a total of ~1/2mm North.  After this, IAS told us we were 0.9mm too far North...What gives?

Jason checked his numbers and confirmed.  We moved the HEPI back South ~1mm and now IAS says we are 0.03mm South.

So now the ACB is being aligned--when they are done, SEI will change/add Viton to vibration absorbers.

Bland, Sadecki
Yesterday, we worked towards attaching the lower reaction chain to the full QUAD.  We:

- Moved it to the 5-axis scissor lift
- Rerouted and secured the cables on this portion of the chain
- Maneuvered it under the ISI next to the main chain
- Pulled the FirstContact on the ERM HR surface (blew with filtered N2 and drag wiped residual ring around the edge near the ID of the gold coating)
- Pulled the FirstContact from the ETMy AR - found that there was sever streaking on the mass under the FC at the top 3 inches of the sheeting, as well as a smear of FC on centerline, right 3". <- Awww, game over.
- Repainted on new FC sheet with PEEK tab.
- Left it overnight to dry since it was so late in the day.

So, unfortunately we could not get the chain attached due to the FC process.

Photo shows that all racks other than the fibre opitcs patch rack have been removed from the MSR and the UPS rack is disconnected from the power circuits at the moment. Underfloor power upgrades are complete. We are still pulling out the old underfloor CDS cabling, carefully while maintaining active systems. A new cable tray has been installed under the floor which cuts across the centre of the main loop. Underfloor drawing is available on DCC 

<A HREF="https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=78581"> Link to D1200078</A>

Betsy, Richard, JeffG, Anamaria

ETMY now has an iMac work station near the clean room.

The electronics chain will hopefully be closed tomorrow, once the feedthrough has been cleaned (to my knowledge the last piece missing).

The models are running on the front end, h2susetmy. We've loaded the filters and epics values necessary (using the load_medm_values and prepare scripts in SusSVN), so it *should* all be ok. In order to fix previously mentioned issues of sign flip and dc gain, we've entered dumb OSEM input filters by hand as a simple zero at 10 Hz and pole at 4 Hz. When the scripts are fixed, we will rerun them to get in whatever filters we decide on. We also copied over the damping filters from ITMY, by hand. Had to change some filter bank gains to match production electronics.

Saved a burt file with today's date in /opt/rtcds/lho/h2/userapps/release/sus/h2/burtfiles/etmy/ and committed it to svn. Just in case. 

Attached are plots of dust counts > .5 microns.

IAS told us we were 1.1mm too South.  I decided this was too far and too unpredictable to move with the Horizontal Actuators attached.  So, we detached them.  The Vertical Actuators are still connected although I want to disconnect/reconnect to relieve stress.

We then cranked the HEPI North ~1mm based on the Dial Indicators.  IAS checked again and said we were now in spec and just 0.4mm South.  I asked Jason about this discrepancy and he corrected his early number to being 1.4mm South.

For the life of me I didn't think I had moved things that far since our alignment back on Dec 21.

Early, Jim & I checked the elevation and level of the ISI Optical Table.  It is just 0.2mm low and shows <0.3mm variation in level.

We swapped the AOSEM with the broken PD.  The S/Ns of the 4 AOSEMs are now:

UL 473
UR 332
LL 428
LR 321

(Corey, Mark, Slim, Zach)

With the Payload extraction from last week, and starting first thing this morning, we were able to empty HAM4 & HAM5, and remove a few more items from BSC2. Today's work occurred roughly from 8:15-11:30 (with a 20min break at 10am after the SEI stack was removed).  All photos for this work is located in Resource Space, here.  This signifies the last removal of an iLIGO HAM SEI from a chamber.  A breakdown of today's activity is below:

HAM4

Removed SEI system (kept Support Table in Chamber).  The Optics Table and Leg Elements were wrapped & bagged.

Note:  Zach found a loose 1/4-20 bolt inside the Optics Table.  This either dropped down there during Payload extract on Fri, or it has been along for a ride for the last few years (and Science Runs).

HAM5

Removed HAM5 Baffle (this will be scrapped for recycling)

BSC2 (& BSC1, BSC3)

Removed (4) Cornucopia Beam Dumps (black glass should be removed off of these guys, and rest tossed for recycling)

Removed (18) Side bolts from the Support Tubes (this is to prevent the need to have someone go into the chamber for BSC SEI extract later).

Removed forgotten allen wrench

Put H1 ITMx & ITMy Suspensions on their stops.

aLIGO HAM 2 has had the old iLIGO stacks removed and replaced with fancy new HEPI piers, frames, and crossbeams. The support tube positions will be checked and fine tuned within the week. Hopefully work can begin on removing the iLIGO HAM 3 stacks and installing the new HEPI structures soon.

A new version of awgstream has been installed for Ubuntu workstations which corrects a bug in which not all channel names are read from the nds.  New version is 2.15.5. 

JimW, ScottS, Hugh

See the attached which is a zoom in of D0900894 sht2.  The upper right cloud area is the SW corner of the SEI ISI Stage0(+Y,-X) looking up.

We tapped and helicoiled the three holes in the right cloud and one of the 'A' holes in the left (not exactly sure which) to accommodate the planned mounting of the ACB dog clamp and alignment pushers.  These holes were vent holes and were never planned to be tapped.  We were lucky in that they were close enough in size to only lose maybe 25% of the thread holding in the aluminum--plenty fine for the 200lb ACB.
The story is this clamp and these pushers can be removed as there is another clamp on the mounting plate.  And we could swap out the hardware later with vented bolts.