ISC Meeting on 2017/7/3 14:00 - 15:00
Participants: Hiro Yamamoto, Arai, Kokeyama, Akutsu, Aso, Izumi, Michimura (eZuce meeting)
Next meeting
2017/7/31 14:00 - 15:00 (July 17 is a holiday)
Minutes
- Vibration from heat links
- information also needed for WAB
- OMC suspension
- frame resonant frequency should be fixed based on vibration isolation requirements
- frame should be made like Bosch frame (screws screwed in the direction of pillars are bad!)
- flipped OMC is inconvenient for alignment
- put beam dumps as much as possible on OMC
- Somiya and Kasuya visit Koji's OMC lab (Amaldi at Caltech)
- DC QPD holder
- stages are not needed for ISC DC QPD
design new ones; they can be very simple [-> Michimura?]
- calibration can be done in different ways
- put strain relief and anchors for cables to protect QPD board
- bKAGRA sensitivity update
- torsion modes of blade springs could complicate the suspension thermal noise
Agenda
PSL EOM Layout re-consideration [Enomoto] (JGW-T1706748)
- Delay-line length decided to be 2.66 m (instead of 8.88 m)
- Modulation phase between f1 AM and PM is always aligned (we need this to be aligned)
Modulation index needed at each EOM is less than measured maximum index by Uehera (JGW-T1605611)
- Optickle simulation by Kohei Yamamoto
- simulation on imperfections (MZ arm asymmetry, MZ lock, EOM phase difference control etc.)
- start with hand calculation, simple setups, and then to full IFO simulation
- Requirement on carrier power loss?
- Comment from Stefan Ballmer
- Similar calculation was done in LIGO in the past. Displacement noise requirement for MZ was tough (~1e-14 m/rtHz).
- Any in-air interferometer suffer from jitter and frequency noise which cannot be suppressed.
- OFI and OMC status? [Somiya]
- look for OFI with larger aperture [Somiya]
- output optics task sharing status?
- OMC baseplate issue?
design review on June 26 at Titech (JGW-G1706853,JGW-G1706854), layout review on July 3
- OMC suspension (Flipped optics or not? 3 or 4 wires? 2 or 1 DC PD? How to damp and actuate pendulum?), OFI suspension
Actuator noise modeling [Michimura,Miyamoto] (JGW-T1503453)
Updated magnet size for cryopayload marionette (ActuatorDesign wiki)
Updated lock acquisition section to derive velocity requirements for suspensions (see ISC Meeting minutes 20170410) [Michimura]
Magnetic noise calculation updated (JGW-T1504459) [Shimoda]
- Added torque effect on magnets
- Needs to implement frequency noise, but FSS modeling with ALS is complicated [student!]
Discuss mirror vibration from heat link
- Ochi is measuring vibration of cryo-shield, which is different cryo system from the mirror
- Yamada is measuring spring constant of heat links
- Miyamoto has the cryopayload suspension model
bKAGRA Phase 1 initial alignment / commissioning plan [Michimura]: JGW-T1605692
- Fixed mirrors for AS port (including SR2)
- Some comments from the Chief Meeting
- Revised schedule seems compatible with PRMI. Why not?
PRMI is an option after achieving the Phase 1 goal, if it doesn't delay the final bKAGRA JGW-T1605595
- Initial alignment does not interfere with ITM Type-A installation work?
- Evacuation of IXC/IYC compatible with Type-A installation work?
- Baffle PDs for initial alignment in vacuum
- confirmed with Akutsu that he is thinking of putting PDs on narrow angle baffles
- vibration isolation for baffle PDs necessary?
- possibility of seeing beams with Tcam
- Revised schedule seems compatible with PRMI. Why not?
- IR/green steering mirrors [Michimura] (see [kagra-isc 01649])
- for POP/POS and green steering in PR2/SR2 chamber, needs picomotors and ~40 cm pedestals
- need this by the end of August 2017 (after PR2 installation on June, before IR initial alignment starts on September)
- proposed mirror specs
- HR reflectivity: more than 99% for both 1064nm and 532nm
- AR refectivity: less than 0.3 % for 1064nm, similar for 532nm
- incient angle: 20-45 deg, s-polarization
- radius of curvature: flat
should be something like: larger than *** km
- size: 2-inch
- wedge: 1 deg
- substrate: Fused Silica
- surface quality: λ/20, 0.1 nm rms roughness
DC QPD holder [Michimura]
we are using oplev QPD (JGW-D1402411) for ISC DC QPD
we will need QPD mounts for them, just like oplev QPD mount (JGW-D1503562)
beam height should be 4inch to use similar mount, with small modification of spacer (instead of 3inch in JGW-D1402607)
- RF PD, RF QPD boxes are designed for 4inch beam height
bKAGRA sensitivity update
- quantum noise calculation was wrong (pointed out by Haino)
- sign mistake, very slight effect on sensitivity
- suspension thermal noise calculation was wrong (pointed out by Komori)
- strange behavior with respect to sapphire blade resonant frequency
- temperature gradient treatment was wrong
- update on sapphire mirror temperature
ITM substrate absorption turned out to be ~30 ppm/cm (JGW-G1706429)
80 ppm/cm was assumed in the last update, so mirror temperature was 23.1 K (JGW-G1605698)
- currently re-calculating the thermal noise, with non-equilibrium condition and less substrate absorption [Komori, Somiya, Ballmer, Michimura]
- quantum noise calculation was wrong (pointed out by Haino)
See this page for other agendas.