jeffrey.kissel@LIGO.ORG - posted 10:03, Monday 10 July 2017 - last comment - 12:54, Friday 14 July 2017(37409)
PCAL Y RX PD Readout Continues to Decay With Temperature
J. Kissel Just posting an update on this -- the H1 PCAL Y RX PD reported displacement continues to decay, likely due to some temperature dependent clipping. This had been a part of the FRS Ticket 8328, but there's little we can do during an observation run to fix this. We've since closed the issue as LONGTERMFIX. AS such, I'll raise to an integration issue, and mark as WHEN VENT (similar to the promised work in Integration Issue 4700). For now, recall that we've switched over to using TXPD as the calibration reference (see LHO aLOG 37166).
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Opened IIET Ticket 8481
I've attached my related notes on this subject, as I've been trying to draw up a history of the issue since the Fall. "Issue History.pdf" is the information I've been able to drag out of aLOGs and long time series, "Investigations.pdf" are the questions I've had and a select few I've answered. Apologies for the rambling nature, these are my personal notes. Short summary of my investigations: temperature correlation on the Rx side is quite clear but higher frequency coherences appear to be only in obvious places (other PCalY OFS and Tx channels, ETMY ISI channels) and I haven't figured out how to measure coherence for long term, slow frequency signals.
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Further investigations and notes will now exist in DCC document G1701350 (see https://dcc.ligo.org/G1701350).