WHAM3 MC2 BandK in chamber LIGO-T1200403-v1
	https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=95644
 Draft

This afternoon we ran the ring heater on ETMY for ~3.5 h, taking cavity scans to attempt to quantify the change in modal spacing with heating.

There's a clear change in the behavior in the 55-60 kHz region (associated with the modulation sidebands), but getting a clear signal for a higher-order cavity mode has been difficult. I also don't understand the downward slope of the phase response curve. I'm hoping to make better measurements tomorrow with a cold cavity to get consistent, clear numbers for the cavity mode frequencies, then try this measurement again.

The adoption of Phase - Phase at 30 kHz for the y-axis is purely to put the traces closer together visually for side-by-side comparisons of the sidebands. The "hot" trace starts at 166.7417, the "cold" trace starts at -162.2308.

Kingsoft water delivery
Praxair delivery at ~10:40
Contractors on-site

Jim B. to End-Y station to reboot PEM I/O chassis
Michael R. to outbuildings to change signs for laser safety
work just north of HAM4 by Eric A.
Douglass using leak detector in OSB Optics Lab
SUS work in and around HAM3

DaveB, JeffG, HugoP,

Added EPICS output channels to monitor errors on IPC receiver inputs (all from SUS) of HAM2 and HAM3 models.

We're going to take a few quick TFs of MC2 to check for mechanical interferences within the suspension since it has been installed.  Next up, we'll set the B&K Hammer/Laser Vibrometer equipment up on MC2 for measurements.

We have also been cleaning up grounding and cabling issues inside the chamber.  This is still ongoing and will migrate to PR2 shortly.

During iLIGO, there were 3-axis accelerometers that were mounted on the tabletops of optics tables. This was done by bolting three accelerometers to the sides of a aluminum cube that was then bolted down to a aluminum plate, which was bolted to the table. This mounting scheme, however, introduced a ~900Hz signal, associated with the resonance of the cube and the plate, into the accelerometer channels. We investigated new mounting schemes to use during aLIGO, and compared them.

For all the tests, we used as our reference an accelerometer that was attached to the table surface with a thin layer epoxy. The hole at the bottom of the accelerometer normally used for bolting it to cubes was sealed with a set screw to avoid having epoxy seep between the threads. The epoxy was Devcon 5-minute epoxy, which was applied to the bottom of the accelerometer. Excess epoxy was scraped off using the flat side of the mixing stick, to have the layer be as thin as we could make it. The accelerometer was then placed on the table, in an area where it was not over any of the holes for bolts, and the epoxy was allowed to cure for 5 minutes before the cable was attached to it. The thickness of such a layer of epoxy is no more than 0.3mm.

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SUCCESSFUL MOUNTINGS:

Items Used:

- Wilcoxon accelerometer, model 731-207

- Devcon 5-minute epoxy

- Wilcoxon 1in. triaxial aluminum mounting cube, model TC1

- Glad polyethylene wrap

- Ultratape 1520CL100P3D

- 520 ft Thermax RGS-316 cable

Z-axis mounting:

We tried adding a layer of Glad polyethylene wrap between the accelerometer and the table. A thin layer of epoxy was first applied to the accelerometer, and a piece of wrap was pulled taut against the bottom of the accelerometer. Then another thin layer of epoxy was applied to the wrap, and then the accelerometer was pressed to the table. The purpose of adding the layer of polyethylene wrap is to isolate the accelerometer from the object it's mounted to, since a thin layer of epoxy may actually allow parts of the metal exterior of the accelerometer to come into contact with the table. The combination of the epoxy and polyethylene wrap added 0.3mm to the heght of the accelerometer (the wrap itself is ~0.5 mils thick). We found that adding this layer does not make the signal deviate too much from that of the reference (see attachment 1).

Triple-axis mounting:

We tried attaching an accelerometer with a layer of polyethylene wrap on the bottom (as above) to an aluminum cube using epoxy, and attaching that cube to the table using epoxy. This also does not make the accelerometer signal deviate significantly from that of the reference (see attachment 2). For actual installation of triple-axis accelerometers, we recommend first attaching three accelerometers to a metal cube using the epoxy-polyethylene-epoxy method described above, outside the LVEA. Once the epoxy has cured and the triple-axis setup is stable, one only needs to use one batch of epoxy near the table to mount the cube. We tested a similar setup but with a (non-conductive) acrylic cube instead, but found that the aluminum cubes give better performance (see attachment 3).

Temporary mounting:

For temporary installations, we tested 1in wide double-sided clear clean room tape. Previously, in iLIGO, double-sided Scotch tape was used, but for aLIGO we wish to use particle-free adhesives such as clean room tape. We found that this mounting allowed the accelerometer to respond to vibrations in a similar way to the epoxied reference (see attachment 4). There were two kinds of clean room tape we tried, one that had a peel-away backing, and one that did not. Since the backing is a hassle to peel off, the tape without the backing is preferred.

Extra long cables:

For cases where extra long cables need to be used for an accelerometer, we verified that the length of the cable does not affect the accelerometer readings. We tested a 520 ft Thermax RGS-316 cable with an accelerometer that was epoxied to the table, next to the reference, and found no effects from using a longer cable (see attachment 5).

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SUB-OPTIMAL MOUNTINGS:

The first mounting scheme we tested was double-sided tape, used in temporary setups during iLIGO. This kind of mounting is useful in temporary installations, not specific to optics tables. The tape used was Scotch Permanent Double Sided Tape, 0.5in wide. Two parallel, non-overlapping strips were placed across the bottom of the accelerometer, which is 1in in diameter, and the accelerometer was pressed to the table surface, again away from any holes. It was placed adjacent to the reference to avoid variations due to positioning on the table. The tape was also found to be non-conductive, so it isolates the accelerometer from the object it's mounted to. We found that when taped to the table, the accelerometer behaves very similarly to one that is epoxied to the table (see attachment 6). However due to cleanliness concerns we opted to use clean room tape for future installations.

Next we compared the iLIGO setup to the epoxied reference. We again found the 900Hz resonance of the cube and plate entering the accelerometer channel (see attachment 6).

Other methods we tried were:

• Accelerometer bolted to aluminum cube bolted to brown plastic plate (one of the iLIGO setups)

• Accelerometer resting on the table (no mount)

• Accelerometer bolted to cube taped to table

• Accelerometer bolted to cube epoxied to table

• Accelerometer taped to cube epoxied to table

• Accelerometer epoxied to cube dog clamped to table

  • + polyethylene wrap between cube and table

    • + foam stuffed in dog clamp slot

    • + foam between dog clamp and cube

  • + different position on the table

  • + cube replacement

    • + tightening of the clamp

    • + maximum tightening of the clamp

  • + foil between clamp and cube

  • + foil between cube and table

  • + foil above and below cube

• Accelerometer with a thin layer of epoxy + polyethylene wrap + a thick layer (0.7-1.0mm) of epoxy to the table

• Accelerometer epoxied to cube bolted to plate

  • + foil between cube and plate

  • + foil between plate and table

  • + foil above and below plate

Maggie Tse, Robert Schofield

The H1 SUS PR2 "safe" burt file was updated and committed to the "cds_user_apps" SVN repository locally in:
'/opt/rtcds/userapps/release/sus/h1/burtfiles/h1suspr2_safe.snap'

This is the file that is SVN version-controlled in the above directory.  A soft-link pointing to this particular file was created in the directory:
'/opt/rtcds/lho/h1/target/h1suspr2/h1suspr2epics/burt/'

with the name "safe.snap" for use by the startup scripts when re-booting the "h1suspr2" Simulink user model.

[Jax, Elli, Alberto, Keita, Daniel, Bram]

After relocking the RefCav we started locking the Arm and setting alignments. Jax and Elli are running the mode-scans.

HAM-ISI Unit #7 - Assembly Validation Testing was validated today. We can now proceed to storage of the unit for future insertion in HAM4 Chamber.
 

Please join me in congratulating the members of the SEI Assembly Team who successfully assembled all of our 7 aLIGO HAM-ISIs  

Reports regading the Assembly validation of previous units at LHO are available in the DCC:

HAM-ISI Unit #1 - Assembly Validation

HAM-ISI Unit #2 - Assembly Validation

HAM-ISI Unit #3 - Assembly Validation

HAM-ISI Unit #4 - Assembly Validation

HAM-ISI Unit #5 - Assembly Validation

HAM-ISI Unit #6 - Assembly Validation

Reports regading the Chamber Side testing of other units at LHO are available in the DCC:
HAM2 (HAM-ISI Unit #4) - Chamber Side Testing
HAM3 (HAM-ISI Unit #5) - Chamber Side testing

Note: Earlier this month we added an Initial In-Chamber Testing section to the HAM3-ISI Phase II - Integration Process testing report. This report has now two sections:

• Chamber-Side Testing: tests performed in the LVEA, after the Assembly Validaton, and before the insertion of the ISI in chamber.
• Initial In-Chamber Tesing: Tests performed after the insertion of the ISI in chamber and before the installation of Suspensions.

This report will be completed with the future tests performed on HAM3-ISI unitl the begining of Phase III - Control and Commissionning.

Kate and I are checking grounding on MC2.  This will require disconnecting the exterior MC2 SUS cables from the chamber feedthru briefly.

The Simulink models for H1 MC1, MC3, PR3, and PRM were compiled, installed, and begun on the 'h1sush2a' FrontEnd this morning during the CDS Tuesday Maintenance period.  The H1 DAQ was also re-booted to begin recording the channels for these models.  All re-boots were clean with no apparent issues to note. 

For future reference, the peak in the ISS_rpn spectrum at ~120Hz appears to be caused by the NPRO's noise eater. It also explains why I had to lower the reference signal to -2.5 from -1.9 to get the diffracted power to a reasonable level (33% down to 2%). This was fixed by turning the noise eater off and on. The attached plots show the noise eater noise (iss_rpn-009) and after it was reset (iss_rpn-001).

This was caused by swapping the FAST cable earlier last week. I was able to set the reference signal back to -1.9 afterwards.

Removed temporary connection used for PR2 testing and connected permanent cabling from HAM3 feedthrus to SAT Amplifiers.

I have put together 4 optics in the Faraday Isolator, out of 7 that should be there eventually. These include:

Ca wedge polarizer s/n 12 currently on the input side
Ca wedge Polarizer s/n 03 on the output side
TGG crystal s/n 10, presently on the "long" tube together with
Quartz rotator

Still not assembled are:

2nd TGG crystal -- will put s/n 09 in tomorrow when Al-Bronze cap is out of the C&B oven
HWP and DKDP -- don't yet have the proper mounts

To install Ca wedges I used a slightly different technique. I cut two 5 mm long sections of the Indium rod, and rolled them together into one fat 5 mm long rod. I then pressed that rod onto the setscrew, and still had enough Indium thickness to tighten on the Ca wedge.

The TGG is installed with Indium foil wrapped around the wedge. I had to roll two slices of the Indium foil together, as the lengths (or even the diagonals) of the foil squares that were delivered are shorter than the circumference of the crystal.

The Quartz is installed withOUT the foil. Instead it contains at least 3 layers of the Indium wire on the cap side to keep it in place.

More photos may be found on the Resource Space.

Attached are plots of dust counts > .5 microns in particles per cubic foot.

[Daniel and Bram]

With the appearance of the laser PZT resonance in the FIBR servo loop, we made a notch filter. We measured the PZT resonance in a previous entry 3857 to be at 287.55 kHz. After some searching and going back and forth we decided to go the easy way, using a passive notch filter (schematic attached 'FIBR_PZT_NOTCH.pdf'), which Daniel already has used in the TTFSS.

By the lack of finding the right capacitors, we used a 500 pF and a 100 pF parrallel, with a 0-100 pF variable capacitor (oh and we got a 470 uH SMD inductor!). With the help of EE-Dave we managed to pack it into a pomona box.

Also attached is a discustingly bad phone photo of the measured response (the RF analyser has a naughty floppy disk drive).

All in all success. We plugged it in and it worked, we can lock the FIBR Servo with a UGF of 28 kHz (another log entry will follow when I get the data from the disk).

PR2 was installed in HAM3 today, and traveled well on the Genie and Arm.  It's sitting against it's cookie cutter, and dogged down overnight.  The crew was Kurt Buckland and Scott Shankle, as well as Deepak and I