Reports until 22:50, Monday 25 April 2016
H1 ISC
sheila.dwyer@LIGO.ORG - posted 22:50, Monday 25 April 2016 (26785)
some SRC asc work today

Jenne, Chris W, Sheila

Today we had some difficulty staying locked at 22 Watts, because of our SRC becoming misalinged (POP90 increasing gradually after power up until we break lock.)

We spent some time investigating signals for SRM control by opening the SRM loop and alinging by hand to minimize POP90.  The error point of our old loop is far from ideal.  We tried a dither and demodulated POP90, but this is a very noisy signal.

Jenne looked at the AS90 dark offsets, which have not been moving around as much lately, and set the gains in DRMI so that 90 and DC centering agreed.  We tried introducing offsets into the DC centering loops to zero the 90MHz signals, but this did not bring the 36 signals to zero.  

Eventually we found a combination of AS36I A and B that seem to cross zero when the SRM is well aligned, and have put that into the guardian:        

        asc_intrix_pit['SRC1', 'AS_A_RF36_I'] =-1
        asc_intrix_pit['SRC1', 'AS_B_RF36_I'] =2
        asc_intrix_yaw['SRC1', 'AS_B_RF36_I'] = 0.5
        asc_intrix_yaw['SRC1', 'AS_A_RF36_I'] = -0.8
 
We have an instability of CHARD yaw that seems to only ring up while we are powering up and sometimes breaks the lock.  We also saw a verry slow (1 minute period) oscillation of PRC2 yaw.  
 
We are leaving the IFO locked at 10 Watts, DC readout, but not low noise, starting at 6:12 UTC.  It would be interesting to see what the cavity pole does with this new SRM input matrix, sine it seems that POP90 is more stable and lower than normal. 
 
 
        asc_intrix_pit['SRC1', 'AS_A_RF36_I'] =-1
        asc_intrix_pit['SRC1', 'AS_B_RF36_I'] =2
        asc_intrix_yaw['SRC1', 'AS_B_RF36_I'] = 0.5
        asc_intrix_yaw['SRC1', 'AS_A_RF36_I'] = -0.8