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Entry  Thu Apr 11 02:00:21 2013, Jenne, Update, Locking, TRY gone??? 
    Reply  Sun Apr 14 15:03:17 2013, Manasa, Update, Locking, Fixing - progress 
       Reply  Sun Apr 14 17:30:14 2013, Manasa, Update, Locking, Fixed 
          Reply  Sun Apr 14 23:20:42 2013, Den, Update, Locking, Fixed 
             Reply  Thu Apr 18 21:12:56 2013, Manasa, Update, Locking, Fixed 
Message ID: 8438     Entry time: Thu Apr 11 02:00:21 2013     Reply to this: 8452
Author: Jenne 
Type: Update 
Category: Locking 
Subject: TRY gone??? 

TRY signals are all gone!  Both the PD and the camera show no signal.  I went down there to turn off the lights, and look to see what was up, and I don't see any obvious things blocking the beam path on the table.  However, Steve has experimentally bungeed the lids down, so I didn't open the box to really look to see what the story is.

Absent TRY, I redid the IFO alignment.  Yarm locked, so I assumed it was close enough.  I redid Xarm alignment pretty significantly.  Transmission was ~0.5, which I got up to ~0.85 (which isn't too bad, since the PMC transmission is 0.74 instead of the usual 0.83).  I then aligned MICH, and PRM.  After fixing up the BS alignment, the POP beam wasn't hitting the POP PD in the center any more.  I centered the beam on the PD, although as Gabriele pointed out to me a week or two ago, we really need to put a lens in front of POP, since the beam is so big.  We're never getting the full beam when the cavity flashes, which is not so good.

Den is still working on locking, so I'll let him write the main locking report for the night.

We see that the PRC carrier lock seems to be more stable when we lock MICH with +1 for ITMY and -1 for ITMX, and PRCL with -1 for both ITMs.  This indicates that we need to revisit the systematic problem with using the PRM oplev to balance the coils, since that oplev has a relatively wide opening angle.  I am working on how to do this.

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