ISC Meeting on 2018/12/15 13:00 - 14:00

Participants:

Zoom meeting: https://zoom.us/j/6676627462

Next meeting

TBD (Michimura has a meeting on Dec 17)

https://www.timeanddate.com/worldclock/meetingtime.html?day=3&month=12&year=2018&p1=248&p2=4399&p3=137&iv=0

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Minutes

Agenda

Short agenda
- MZM updates (analytical calculation status, agreed to do 3f for O3, technical review in Jan 22)
- RF PD and RF QPD preparation (frequency tuning, 3f and 2f PDs, in-vac)
- DRMI preparation status (electronics, Optickle, suspensions, POP and AS optics)
- Yarm preparation status (electronics, suspensions, POS green optics and obelisk)
Main topics for Phase-2 [Michimura]
- Fix initial alignment scheme for full IFO
  - Enomoto?
  - For XY arm JGW-G1808462
- Finalize ALS scheme and RF AM generation scheme and finalize lock acquisition scheme
  - Enomoto?
- ISC modeling, especially ASC modeling, for intermediate IFO configurations
  - Tanioka for ASC?
- Cabling diagram
  - Almost finalized JGW-D1808394
- In-vacuum RF PD and RF QPD
  - Izumi will ask LIGO people first. And ask Doi for handling fabrication?
  - Laser welding would be tough (resonant circuit cannot be re-tuned)
  - Use similar design to OMC DC PD preamplifier?
- Readout DC PDs and OMC
  - In-vac amplifier board made JGW-D1809177
  - Cabling diagram around OMC JGW-G1809012
- Design output optics on optical tables
  - REFL [Aritomi] (done buying parts) Output Tables Optics wiki
  - POP [done for green; ? for IR]
  - POS [done for green; ? for IR]
    - Obelisk with a hole and attachement designed JGW-D1909579
  - TRX/TRY [K. Nagano for both IR and green]
    - TRX designed and assembled JGW-T1808962
  - AS [??]
  - 20 mm diameter optics post to be ordered by Izumi
RF PD and RF QPD tuning [Michimura]
- The number of RF PDs and RF QPDs necessary are as follows:
- RF PD
  - f1, f2: in-air 6pcs, in-vac 5pcs
    - in-air: REFL, IMMT2T, POP, POX, POY, AS
    - in-vac: REFLVAC x2, POPVAC, POXVAC, POYVAC
  - f3-f1, f3-f2: in-air 1pc (needs design)
    - in-air: REFLNRSB
  - 2*f1, 2*f2: in-air 2pcs (needs design)
    - in-air: SPOP, SPOS
  - 3*f1, 3*f2: in-air 1pc (needs design)
    - in-air: REFLTHREEF
- RF QPD
  - f1,f2: in-air 6pcs, in-vac 6pcs
    - in-air: REFL A/B, POP A/B, AS A/B
    - in-vac: REFLVAC A/B, POPVAC A/B, AS A/B
- AEL will take care of f1 and f2 PD/QPD tuning (9pcs of RF PD and 15pcs of RF QPD) JGW-L1909582
- A/I: Design in-vac housing for RF PD and RF QPD
- A/I: Design 3f, 2f (and f3) RF PD resonant/notch circuit
ALS report [Enomoto]
- Noise mainly comes from fiber noise and reduced to RMS of 13 Hz.
  - Fiber noise cancellation might be necessary.
    - Requires AOM and ~10% coupler.
  - Windshield for PSL table and POP table?
Mach-Zehnder modulator [Yamakoh]
- Not sure if requirement calculation using Optickle is reasonable or not
  - Requirement calculated directly from the TF from MZI displacement noise to DARM and that calculated using TFs from MZI displacement to multiple f1/f2 PM/RAM amplitude/phase noise, multiplied by TFs from multiple f1/f2 PM/RAM amplitude/phase noise to DARM do not match.
- A/I:
  - Analytically calculate TFs from multiple f1/f2 PM/RAM amplitude/phase noise (LIGO-T1500559) to DARM and compare them with Optickle.
  - Analytically calculate TFs from MZI displacement to multiple f1/f2 PM/RAM amplitude/phase noise
- PD noise was updated and worse
- A/I: Look into requirement calculations again
  - Phase noise for f1 RAM, which comes from asymmetry of 1st MZI, gives the most stringent requirement
- Displacement noises of 1st and 2nd MZI do not meet the Phase 2 requirement.
- Measured modulation depths for each EOM alone fluctuates very much. To be investigated.
- Plan for O3
  - Agree to do 3f in O3 (Minutes of the Commissioning Meeting 20190108)
  - Technical review on Jan 22
    - Displacement noise, modulation depth, residual amplitude modulation, phase noise, long term stability
    - Disassemble 1st MZI and 2nd MZI? Just block one of the arms (loose 7/8 of the power)?
    - Future plans?
- Future plans
  - Make monolithic MZM?
  - Make a wind shield?
RF modulation system
- Three-f or f3
  - Agreed to work on both three-f and f3 for redundancy
  - O3 requirement for MZI was calculated (and met?)
    - A/I: The deadline and when to disassemble MZI (remove some of BSs) when the requirement was not met are to be discussed
  - A/I: How to proceed with broadband PDs for f3-f1/f3-f2? Modify our resonant RF PD? (BB PD also necessary for SPOP (and SPOS))
- Low noise VCO
  - Two Prototype Low Noise VCO for ALSX and Y assembled (JGW-D1808968), and noise of the one of them was measured. Meets the requirement.
  - We need three real ones for ALSX, ALSY and FSS
    - 110MHz for FSS? FSS AOM driver broken. Status?
  - For PLLX and PLLY, Keysight E8663D is used.
    - A/I: Need to develop a code to sweep the frequency.
- RF source
  - Harmonics Generator arrived
  - We currently have 6 Agilent N5181B, but we need 7 JGW-T1706762
    - PMC PDH (15MHz)
    - Refcav PDH (51.75MHz)
    - IMC PDH (13.78MHz)
    - seed for Harmonics Generator
    - ALSX PDH (33MHz) (NOTE that 33MHz for ALSX PDH, not 32MHz)
    - ALSY PDH (32MHz)
      - Not necessary until Yarm commissioning starts (mid-Nov?)
    - seed for ALS VCO (~70MHz)
      - Now uses Keysight 33611A-OCX klog #7019
  - RF amplifier for EOM requested to AEL JGW-T1809260
Common mode servo board CMSB wiki JGW-G1808547
- Summarized, requested to AEL JGW-T1809210
- We will make 20 boards, and 10 will be assembled as chassis
- We currently have 5 chassis and used for 1st MZI, IMC, CARM, PLL X, ALS PDHX
- Needs 4 chassis more soon: 2nd MZI, PLL Y, ALS PDHY, ALS COMM summing node
- 6 chassis for spare: MZI, IMC, CARM, PLL, PDH, summing node
OMC status
- OMC was locked from the digital system klog #6846
- DC PD Preamp SN1 was broken, but replaced
  - transfer function of DC PD should be measured within a few % for calibration
- DC QPD amplifier not arrived yet
- Calculations on DC power and circuit noise -> Somiya & Arai
  - Koji's calculation: DCPDCalculation
- Electronics status
  - In-vac DC PD amplifier board finalized JGW-D1809177
  - In-air DC QPD amplifier board not arrived yet
ITMY inhomogeneity JGW-T1808715
- We should check impact on sensitivity and locking as soon as possible
  - For both O3 and full bKAGRA
- There was a discussion whether we should re-optimize OMC for BRSE or DRSE without homodyne angle optimization.
- ASC simulation by FINESSE show worse signal when ITMY inhomogeniety is added (a few % degradation in shot noise?)
- higher order contents, especially odd-order modes are worse
- But still need to check the Finesse code (alignment loop not closed yet)
- FINESSE calculation on ASC was not reliable since Gouy phase tuning was not done
- Working on Gouy phase tuning
General comments from Koji's Kamioka visit
- Many people assembling and installing things without looking at drawings
- Many works that can be done remote are done at Kamioka. Work at Kamioka is very expensive.
- Slow channels may be needed for monitoring things(PLC based? Beckhoff? Acromag?)

RF generation using Mach-Zehnder interferometer [Kohei Yamamoto] JGW-G1707309 JGW-G1807655 JGW-G1808029
- simulation on imperfections (MZ arm asymmetry, MZ lock, EOM phase difference control etc.)
- calculate requirements on MZI displacement, EOM modulation phase difference, EOM imbalance
- Requirements derived from full Optickle simulation and those derived from transfer function between displacement of MZI and sideband power kind of matched after implementing RAM into calculation for the latter. However, we need more investigation on the following issues:
  - Modulation depth for RAM generating EOM changes the requirement.
  - Spectrum shapes of the requirements for mid-fringe do not match. Maybe coming from accuracy of the mid-fringe?
  - Unknown frequency response of the transfer function from the displacement of MZI and sideband power
  - Check if caluculated RF oscillator amplitude noise is relative one or not with simple Optickle model
- calculations for requirements on delay line lock displacement noise, parallel EOM MZ lock displacement noise, EOM modulation phase difference, EOM imbalance on-going
- Relative f1 PM and f1 AM also needs to be adjusted (CQG 31, 095003 (2014)). Another EOM for f1 or relative amplitude adjuster between two EOMs?
- 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.
- Ref: LIGO-T040119
- MZI implementation starts in May, probably before high power laser installation
- RF oscillator noise requirements for MZI should also be calculated
IMMT1 and IMMT2 transmission [Michimura, Takeda]
- IMMT2 transmission optics are too much squeezed
DC QPD holder [Michimura]
- 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
- 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
OMC and OFI [Somiya]
- look for OFI with larger aperture [Somiya]
- DC PD and DC QPD [Michimura]
  - DC PD not available. Look for product with similar specs
  - DC QPD available from RS
In-vacuum RF PD and RF QPD
- we need them within 1 year, considering OMC REFL and AS RF
In-vac beam-dumps
- required spec?
Actuator noise modeling [Michimura,Miyamoto]
- Summarized in the paper JGW-P1707051
- Needs to implement frequency noise, but FSS modeling with ALS is complicated [student!]
- Discuss mirror vibration from heat link
  - Meeting on July 14 [Yamada, Miyamoto, Ushiba, Michimura]

See this page for other agendas.