Reports until 20:34, Thursday 31 August 2017
H1 ISC (ISC)
thomas.vo@LIGO.ORG - posted 20:34, Thursday 31 August 2017 - last comment - 09:08, Friday 01 September 2017(38476)
Trouble Re-locking

Sheila, Jeff, Corey, TVo

After opening the gate valve at ETMX, we started locking to measure the charge in-lock using Sheila's script in aLOG-38387

However, we had trouble getting past the CARM_10PM state and Sheila noticed that the alignment might be bad because of the ratio of REFL power locked to unlocked was too low and the PRC Gain was lower than normal as well.  Even after running initial alignment twice, the same problem still persisted so we're thinking there may be some extra absorption in the arm cavities, we will follow up tomorrow.

Comments related to this report
jeffrey.kissel@LIGO.ORG - 09:08, Friday 01 September 2017 (38479)
Link 

For the record, Sheila referenced LHO aLOG 36439 that documents symptoms of poor alignment during the CARM reduction causing lock losses. However, after several initial alignment attempts, and some by-hand tuning of the alignment, the power recycling gain did not improve; hence this investigation into arm losses.