• TAC_Meeting-Feb_11

Feb 10th, 2011 Meeting of the 40m Technical Advisory Committee

Link to the slides https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?docid=33398

Report from the TAC

I. Personnel

1. Current members

2. Alberto submitted his thesis: https://nodus.ligo.caltech.edu:30889/svn/trunk/alberto/thesis/main/

3. Suresh joined the team
4. Jamie is coming (Feb)

II. Overview of the presentation

• Current Status

  1. Under each subsystem (IFO&SUS, RF, LSC, CDS) we discuss

     1. An overview of the subsystem
     2. Work completed since last TAC
     3. Work in progress just now
• Future projects
  1. Compare and contrast the features of the 40m vs (LHO and LLO)
  2. Outline projects which are planned for the near future (6 months)
  3. Specific deliverables where ever possible.

III. Current Status / Recent and Ongoing Work for each subsystem

1. Optics and Suspensions
   • An overview of the new optical layout (high lighting the differences from the previous plan)
     • ITMs and ETMs are dichroic, mass/finesse chosen such that the radiation pressure effects are comparable to Adv
     • PRC is resonant with 11MHz, 55MHz and the carrier (PSL)
     • SRC is resonant with 55MHz
     • Additional optics installed to route the green beam from the end tables to the PSL table
     • Tip-tilts are installed with new suspensions: some characterisation remains
   • Status:
     • PSL table raised
     • All optics suspended and installed according to the new plan in the vacuum chamber
     • The chamber has been evacuated and has reached operational vacuum pressure
2. Length Sensing and Control
   • An overview of the
   • Current status
     1. PSL locked to MC length (in IR)
     2. MC length locked to beat-note frequency (in green)
     3. X-end laser frequency locked to X-arm length (in IR)
     4. Single-mode fiber brings X-end NPRO light to the PSL table for IR beat
   • Work in progress:
     1. Measurement of the coherence of the two lasers when locked to the arm cavity
     2. Acquiring a deterministic lock
3. Electronics (RF system)
   • An overview of the new RF system
     • The layout and the measurement scheme
   • Status
     • Under construction: Multiple frequency RF generator to preserve the phase noise performance of the oscillator
     • Under construction: RF signal distribution (oscillators, splitters, amplifiers, etc.)
     • Done: Triple-Resonant EOM (New Focus KTP + resonant circuit) prototype completed
     • To be done: Finish the PDs / Install the photodiodes on the tables; characterisation of all the PDs underway
4. Control and Data Systems
   • Done: All of the new CDS hardware installed
     1. All 5 IO chassis and computers installed: c1lsc, c1sus, c1ioo, c1iscex, c1iscey
     2. New frame builder computer and code running, recording, and serving data
   • Done: Local damping has been achieved on all suspended optics with the new CDS system
   • Done: Have working reflected memory networks communicating between computers
     1. Both old GE Fanuc and the new Dolphin PCIE reflected memory networks installed

IV. Future Projects

1. Comparison of the 40m and the LHO/LLO instruments
2. Length Sensing and Control
   • Deterministic lock acquisition through auxiliary green laser locking
   • Locking sequences: successively increasing the length of the primary length reference
   • Coherent lock of the three lasers (PSL and two auxiliary lasers)
   • Dither beam alignment
3. CDS
   • To be done: Finish setting up the LSC controls
   • To be done: Integrate green locking into the digital controls system
   • Realize the idea of "simulated plant"
4. Adaptive seismic noise cancellation
   • seismometers are back in action installed near the 40m arms
   • determination of the transfer function matrices
   • closing the feedforward loops to arm cavities
   • implementing the algorithms in CDS

V. End