keita.kawabe@LIGO.ORG - posted 23:47, Wednesday 09 May 2018 - last comment - 10:18, Thursday 10 May 2018(41924)
PSL main beam path done (ALS path later) (Cheryl, Sheila, Keita)
We iterated between IO_MB_1 and IO_MB_2 without moving EOM as planned. One difference from the plan was that it was my misunderstanding that Cheryl had two irises on the main beam path (there was only one), so we used EOM and iris as our fiducial.
As expected this made ALS path totally misaligned such that it doesn't clear Faraday, that will be adjusted later.
Ooopps! This is potentially a worst case scenario. I made log entry 41922 @ 21:21 hrs. local intended for the Thursday morning 0900 meeting audience thinking that anyone who might potentially energize any of the High Volts had left for the day. I hadn't seen anyone in the Control Room, LVEA or OSB offices for hours. Is this log entry just a late recording of activities from earlier in the day, or, where people in the PSL "chomping at the bit" awaiting the "go ahead" from me confirming that we were on turbo pumping? If so, and if any High Volts had been energized last night after my entry, then we may have risked Paschen arcing!
Regardless, people, I think this situation (or potential situation) is symptomatic of a culture that is developing that is going to "bite" us sooner or later. If I had my druthers, we would slow down the pace a little. In the past, I didn't feel time pressure to make this hand-off to the next interested party. Typically, we would pump with the turbos for a day or more before declaring it okay to resume IFO work.
This was an alog entered well after the work completed. (Cheryl & Keita left the LVEA at ~4:45pmPDT.)
They were working on alignment in the H1 PSL Room. The LVEA is Laser SAFE (so the light pipes for the ALS & PSL shutters are CLOSED).
To re-enforce what Corey said, this was work that was done earlier during the day and confined to the PSL enclosure (no beams were sent into the chamber, no high voltage in chamber was used, and no viewport work.)
Before starting this, we measured the power before and after the EOM, which was 17.8mW at the input and 17.9mW at the output. We changed the power up and down while we were working, and attempted to re-measure after the work was finished (9.08mW before the EOM, 9.5mW after). We found that the scattered light from the high power beam dump that is near the EOM was showing up as significant errors in our power measurements, which probably explains why we found EOM transmissions greater than 100%.