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==== Past week report ==== At Kamioka (Mark, Fabian, Enzo, Hirata-san): |
==== Past two weeks report ==== At Kamioka (Mark, Enzo, Kozu-kun): * Supported IA team. * Replaced LPCDs for IM OSEMs with HPCDs for increased pitch/yaw range. * Re-zeroed OL after significant change of beam position during IA. * Re-laid-out OL to improve focus of lens to LEN QPD. * Offloaded the pitch/yaw actuation at the IM OSEMs using the IM pitch/yaw picos. * Enzo worked on design of control loops using the OL. * Kozu-kun worked on diagonalizing the OL. |
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* Inspected LLB in tank - in a good position, but not very clean - apparent water spots and dirt. * Found the geophone adapter plates. * Retested SF FR stepper - still good. * Finally got SF LVDT working: * Found a short in the primary coil due to Al foil used for mechanical reinforcement at vacuum feedthrough connection. * Did a full calibration and found that linear range was too small (0.75 mm!) and did not cover nominal keystone height. * Decreased gain to increase linear range. * Adjusted the height of the yoke and secondary coil unit to center the linear region around the nominal keystone height. * Implemented velocity damping. * Found all parts for the LBB and damper rings. * Cu segments and some other parts were very dirty - wiped carefully for now, but should be properly cleaned before final install. * Outrigger parts for LBB have M16 thread cut directly into Al but should have had M16 helicoils. This is a galling risk with Ag-coated rod receptacles. Hirata-san organized rework. * Some special lock nuts are in short supply and are being borrowed from supply at ATC for next batch of BFs. * Made remaining two geophone in-air descrambler cables (total three). * Installed a thermometer supplied by Kokeyama-san on the tower around the BS tank. * Prepared the SF damper. * Designed a pattern of magnets for the two-segment arrangement of SF damper and laid it out on the magnet ring with the template. * Moved the Cu segments on SF cap by 30° (the cap had not been in the right position earlier). * Reinstalled PI: * Raised the PI with the crane and hooked the SF damper ring. Some of the rods did not fit the receptacles due to tolerance issue, but by going through a large number of rods and receptacles, we found three working sets. * Craned the PI onto the frame and suspended the SF/... section, this time with the hex cable clamp on the F0-SF rod. * Tensioned the PI yaw return spring, installed (but did not cable) the yaw stepper and adjusted the yaw of the SF/... section. We worry the return spring is not stiff enough. * Installed (but did not cable) the geophones. * Recentered the IP. The extra weight from the geophones (≈42 kg) and SF damper ring (≈17 kg) had brought the IP to near the point of instability, so we removed one arc weight (≈17 kg) and rearranged the other two in the top row to be symmetrical. * Added ballast to set the height of the F0 keystone. We now have about 6 kg in hand (due to removing one of the Cu segments for the SF damper). This should be enough margin for cables, temperature fluctuations etc. |
Mitaka (Fabian, Hirata-san): * Hirata-san published his inventory of SR parts on Dropbox. |
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==== Plan for coming weeks ==== For more detail, see [[KAGRA/Subgroups/VIS/TypeB/ToDo]]. |
==== Plan for week of 11/13 ==== |
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Weeks of 5/22, 5/29: * Retest SF stepper every day, to see if problems recur. * Find/install geophone adapter plates or improvise replacement. * Reinstall PI, this time with rods and damper ring. * Reinstall PI-SF rod, this time with hex cable clamp. * Cable/test PI geophones LVDTs and steppers. * Reinstall LBB blade units. |
Kamioka: Mark * Attend commissioning workshop at U Toyama. * Be person-on-site for BF work. * Set up for mirror gluing. |
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Mitaka: Fabian and Hirata-san * SR procurement. * New PI GAS FR design. * BS LBB ballast mass design. * SR cable lamp design. Mitaka: Enzo and Kozu-kun (Wed, Thu) * Servos * TFs of BF * Documentation |
Scraps of text for incorporation in the VIS Meeting Minutes
KAGRA/Subgroups/VIS/MeetingNAOJ
Type B (Mark)
Past two weeks report
At Kamioka (Mark, Enzo, Kozu-kun):
- Supported IA team.
- Replaced LPCDs for IM OSEMs with HPCDs for increased pitch/yaw range.
- Re-zeroed OL after significant change of beam position during IA.
- Re-laid-out OL to improve focus of lens to LEN QPD.
- Offloaded the pitch/yaw actuation at the IM OSEMs using the IM pitch/yaw picos.
- Enzo worked on design of control loops using the OL.
- Kozu-kun worked on diagonalizing the OL.
Mitaka (Fabian, Hirata-san):
- Hirata-san published his inventory of SR parts on Dropbox.
Plan for week of 11/13
Kamioka: Mark
- Attend commissioning workshop at U Toyama.
- Be person-on-site for BF work.
- Set up for mirror gluing.
Mitaka: Fabian and Hirata-san
- SR procurement.
- New PI GAS FR design.
- BS LBB ballast mass design.
- SR cable lamp design.
Mitaka: Enzo and Kozu-kun (Wed, Thu)
- Servos
- TFs of BF
- Documentation