Feb 28th, 2013 Meeting of the 40m Technical Advisory Committee

Link to the slides https://dcc.ligo.org

Report from the TAC

Call in instructions: BR (866) 380 - 5536 BR International: (816) 249 - 4731 BR Code: 6263958709 BR

1. Title
2. People at the 40m
   1. 2 Ugrads
   2. Grads - Jenne + visiting grads (Annalisa, Yuta)
   3. Manasa, Jamie
   4. Koji, Rana, Steve

   5. OUT Suresh, Den => LLO, Kiwamu => Graduate => LHO

   6. IN Manasa
3. Outline - Overview
   1. ALS: Initial testing done / upgrade of tables
   2. Adaptive noise cancellation progress (MC+2 arms)
   3. IFO locking (main topic)
4. Full locking (Jamie)
   1. Long lasting issue of PRC/SRC mode instability - It seems solved.
5. If there is any real progress for PRFPMI locking (Jamie)
6. What was the problem (Jamie)
7. What is the current solution (Jamie)
   • (Quantitative evaluation)
8. Full locking plans for 2013 (Jamie)
   1. What will be the future permanent solution
      1. Replacing the mirror?
      2. Adaptive control?
   2. Towards full locking
      1. Investigation of the DRMI sensing matrix
      2. Investigation of the signal normalization scheme
      3. Integration of the ALS with LSC
      4. Investigation of the ALS noise in various configurations (FPMI, PRFPMI, DRFPMI)

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Backup slides

1. Purpose of the 40m
   1. Similar LSC scheme to aLIGO

      1. 11 & 55MHz PM (cf 9/45MHz for aLIGO)

      2. 3f demodulation
      3. small asymmetry 3cm (cf 8cm for aLIGO)
      4. same arm finesse (450, cavity pole differs from aLIGO by x100)
      5. ALS
2. ALS
   1. realized in 2011, published in JOSA A in 2012
   2. further refined in 2012
      1. dual arms
      2. improved electronics (beatbox)
      3. phase tracker
3. ALS Status (Yuta/Koji)
   1. final result (Yuta's measurements in 2012)
4. ALS remaining issues (Yuta)
   1. integration of ALS and LSC
   2. FPMI excess noise (Yuta's measurements in 2012)
   3. End table refurbish (Manasa)
      1. Purpose:
      2. Method:
      3. Status:
5. Adaptive cancellation progress (Jenne)
   1. Simultaneous adaptive seismic cancellation: MC/Xarm/Yarm
   2. Future?