Elenna, Sheila

Summary:  We reverted a large move of SR3 to be more like O4 in the SRC alignment, which we hope will help with the mode hopping problems.  We made phased reflair 135 phasing, and can now lock DRMI on 3F.  

• Elenna did a careful manual alignment in PRMI.
• We moved SR3 pitch back to the alignment slider values that it was at in O3.  This was changed during BBS alignment, without the arms, to match where we thought we needed ITMY to be (see 91567).  While the Yarm was open we moved ITMY but hadn't un done the move of SR3.  We have been seeing mode hopping problems, which in the past had been a sign of some change in alignment in the SRC.  
  • Elenna locked SRY and walked SR3 back to the O4 sliders, SR2, and SRM to keep SRY locked.  
  • At the end of this process we checked the power on AS_C, with 8.8W on PRM according to IM4 trans, which was in agreement with expectations (22mW into HAM6 according to AS_C, we expect 20mW but this power has always reported slightly high.)
• With DRMI locked, Elenna walked SR2 in steps until build ups got worse, then corrected the build ups with SRM.  After each step we looked at AS_C centering to judge if this was a step in the right or wrong direction.  By the time AS_C was centered there was a clear improvement in the power in OPO18 and more stablity of POP18, although the powers have been higher other days.  Screenshot
• With DRMI locked, Elenna transitioned PRCL to 27I (matrix element doubled compared to what it used to be).  We then put a line on SRM M3 test at 88 Hz, 30000 counts, and turned on notches in all DRMI loops.  We saw that SRM was mostly showing up in 135 Q, not I, so we adjusted the phase from 145 to 55 degrees to get SRCL into I.  
  • Elennal did a broadband SRCL excitation and sees that the 135I error signal matches 45I error signal well with a matrix element of 1.3 for 135I to SRCL.  We also did a prcl excitation and see that to cancel the PRCL signal in 135 I we will want to add a matrix element of 1.5 for 27I to SRCL.  (We used userapps/lsc/h1/template/phase_REFLAIR_3F.xml)
  • SRCL moved to 3F with 27I at 1.5, 135I at 2.5, this worked. (SRCL, used to be 2.1 27I, 1.7 135I)
• In 2018, we added a 27I to MICH matrix element: 43183 and 43190.  We rechecked this with the same PRCL exctitation used to tune the SRCL element, it should be -1.88, used to -0.67 .  Elenna measured a braodbadn MICH excitation, determined the matrix element should be 2.82 (used to be 1.115) 
• DRMI is transitioned to 3F, and Elenna put these matrix values in guardian.  
• OLGs of all three DRMI LSC loops are attached, on 3F.