Danny,  Sheila

• DSOFT P
  • Earlier this evening Hang moved PR3 pitch from -116.8 to -112.7 and the PRG improved from 46 to 47.  We then lost lock because of the ~0.5Hz DSOFT instability.  
  • Danny and I tried engaging the oplev damping to help with the ~0.5 Hz instability, then attempted to move DSOFT P, but lost lock due to the same instability.
  • Perhaps manually walking SRM to keep the DARM cavity pole high would help avoid the instabilty
  • We saw high coherence between DARM and DSOFT P (because the bandwidth of DSOFT P is increased to try to address the DSOFT instability).  We copied the cut off from CSOFT P to DSOFT, and it works fine reducing the noise from 15-20 Hz.  (see attached spectra)
  •  
• Our spectrum is dominated by ASC noise below 50 Hz, and there is high coherence with LSC from 45-100 Hz.  We ran A2L, and also tried running the A2L script that Gabriele writes about here with the 30 Hz notches on.  We used default settings and got an error:
  • >>> Starting line in H1:SUS-ETMX_L2_DRIVEALIGN_Y2L_EXC (freq = 30.000000 Hz, ampl = 1000.000000)
        Measuring...
        Stopping line in H1:SUS-ETMX_L2_DRIVEALIGN_Y2L_EXC (freq = 30.000000 Hz, ampl = 1000.000000)
        Measured coherence = nan, transfer function abs = nan phase = nan deg
    >>> Results <<<
        Ratio Y2Y/Y2L: nan + 1j * nan
        Coherences: Y2Y = 0.999951, Y2L = nan
        Imaginary / Real part of ratio = nan
        Current Y2L value = 2.946300
        New     Y2L value = nan
    >>> Saving A2L gains to /opt/rtcds/userapps/release/isc/common/scripts/decoup/rec_LHO//20181018/data_ETMX_YAWa2l_decoup_235653.txt
     
• We added the low pass in DARM (FM9 in DARM1) to the guardian, we have still been loosing lock about once an hour.
• We saw improvements in the range but don't know why.  (see attached spectra)
• To save some time with lock acquisition we damped the ETMY bounce mode, +60 degrees gain -1 filter on and a gain of 1 in the gain setting.  This damped it well a few times.  We put this damping in the guardian.