WHAM4 was already unlocked so all HAMs are unlocked except HAM6. Will unlock BSC1 & BSC3 likely tomorrow. We've relieved the DC position with the big springs so isolated/un-isolated & locked position (during vent) are the same, to a point. Will tabulate the diffs and report.
R. McCarthy, M. Pirello
We replaced the spare (S1001082) Triple Top Coil Driver with the repaired original (S1100195). The original had a bad relay and was swapped back in December with the spare. The unit was repaired, tested, and replaced into its original configuration.
Alog of events leading up to this: 39877
Daniel, Dave:
Daniel restarted the EPICS IOCs for h1ecat[x1,y1]. This fixed the DAQ EDCU and the hourly autoburt connection issues.
Daniel, Dave:
new models for h1lsc, h1omc and h1sqz were installed. No DAQ restart was needed.
2018_01_02 13:31 h1lsc
2018_01_02 13:31 h1omc
2018_01_02 13:31 h1sqz
Pictures of HAM2 West and East doors showing all viewports have Lexan covers.
No PSL stats this week as PSL is still down for the holiday break.
The afternoon of December 22nd I went back into the optics lab and made a few measurements to try to understand why our Faraday isolation was only 20dB(see alog 39861). It turned out that one of the TFPs had an extinction ratio that didn't meet the spec, and by switching the positions of the TFPs I was able to measure an isolation of -28dB.
Thin Film Polarizer extinction ratio:
To measure the extinction ratio of each of the TFPs I used a set up very similar to the image in 39861, with the rotator removed (PD monitoring input power in position A, PD monitoring TFP transmission in position C which is after the Faraday path, used chopper to measure transfer function between PDs).
After the fiber collimator, there was already in place a PBS mounted to clean up the input polarization by reflecting horizontally polarized light. I also used whichever TFP I wasn't measuring to further clean up the polarization. I rotated the half wave plate to measure the maximum and minimum power transmitted by the second TFP to get its extinction ratio. For the TFP mounted with the backplate labeled SN9, I got a ratio of 2220:1 (coated side facing down in the mount, so that incident beam hit uncoated side first), for the one mounted on the backplate SN08, I got 336:1 with the coated side down and 577:1 with the coated side up (so that the incident beam first hits the coated side). The spec for these TFPs is greater than 1000:1 (spec here)
Better Faraday Performance
In the original set up, SN08 was the first polarizer in the Faraday (the one closer to the OPO), and both TFPs were mounted coated side down. Scattered light from the interferometer will be mostly in the polarization to be rejected by the TFP closer to the OPO, so swapped the two positions. Now SN09 (2220:1) is mounted coated side down closer to the OPO, and SN08 is mounted coated side down further from the OPO.
With this arrangement I repeated the measurements of isolation, transmission, and backscatter (I also increased the laser power compared to 39861). For transmission measurements I got 95.6% and 97.6%, for isolation I got -27.9 dB and -27.8dB (0.16%), and for backscatter I got -40dB and -41dB.
Sheila, Nutsinee, TJ
We made a couple of measurements to try to measure the Faraday rotation angle, but our measurements don't provide any better information than the constraint placed on the error by the isolation measurement.
We tried a few methods of measuring this, including setting the half wave plate to maximize transmission with the rotator both in place and removed and comparing the angles (47+/-3 degrees). We also used a polarizer in a rotation stage mounted after the Faraday and setting its angle to maximize transmission with vertically polarized light (with HWP and TFP after rotator left in place) and with the light directly out of the rotator. This method gave us fairly good accuracy (about 1 degree) but we found that repeated measurements varied by up to 5 degrees, so there must be something mechanically unreliable about the rotation stage we were using.
Monthly chiller filter check shows all OK. The filers are clean and clear. I added 200ml water to Crystal chiller, and 100ml to Diode chiller. Diode chiller was not low on water just added what was left over in the measuring cup from the Crystal chiller top off. Closing FAMIS #8304.
After configuring h1nds1 to once again use framed data from h1ldasgw1 before the break, I forgot to fix the /frames symbolic link. I have corrected this and framed data (full and second trends) should be available. h1nds0 was unaffected.
I'll go ahead and do an impromptu site inspection while I'm here. I expect to be here between 60- 90 minutes. I will make a comment to this log entry when I leave
Vacuum pumps and purge air are all normal. local gauge indications Vertex MTP (7.7 x 10-7 torr, 1.0 x 10-2 torr), XBM MTP (8.8 x 10-7 torr, 6.9 x 10-3 torr) and YBM MTP (1.1 x 10-6 torr, 8.5 x 10-3 torr) SITE INSPECTION: 1) JOY fan (HVAC) at X-mid is quite whiney/screatchy and noticeablly noiser than the rest of the fans on site -> I was unable to open the door to inspect as the internals of the door handle seem broken. 2) Filler cap on main chiller (ante room?) was not in place, i.e. just dangling. -> I left as found. 3) Weld shop door was found to be unlocked -> I locked it. 4) VPW above-ground waste water tank must be full as the "RED" lamp is illuminated. 1705 hrs. local -> Kyle leaving site now, no one else here at this time.
Starting around 6pm Friday 29th PST we are seeing auth problems when accessing the internal CDS web pages using the standard LIGO authentication option. The work around is: when you get the web page with the LIGO logos, if you select the LHO Backup option you should be able to view the web pages.
Both Beckhoff end station slow controls systems are having problems. h1ecaty1 continues to run but not allow connections to the DAQ-EDCU nor the hourly autoburt. h1ecatx1 froze up on Christmas Eve (23:37 PST). Both require IOC restarts.
No other problems have been found.
In other words, select the middle option.
If the LOGO for LHO:Backup is not presented, press the "Allow me to pick from a list" button to make your selection.
The site is secure. The entire site is covered in ice and showing no signs of melting as of this moment. Let's hope the weather man is correct about the warmer temps tomorrow. All buildings checked.
IP 1,2,3 are being pumped via aux carts (valved out now). IP4 valve dead space was pumped out with loaner "cube" cart. GV5 annulus is set up to pump next week.
HAM 1 is on turbo powered through safety GFCI in case of a power failure.
All three turbos are valved into main volume and backed by local scrolls. QDP80s are OFF; water valved out.
Attempted to start leak checking but leak detector was not budging below 1.1e-8 Torr-L/s background. Postponing till next week.
Mark & Tyler worked on TMDS tables.
Dick G. was onsite for a while in the EE lab.
John Deer tech was on site for a while working on big green machine.
No issues to report.
Except that the janitor closet next to unisex bathroom in OSB has a slow leak in faucet.
The drip in the closet is condensate, not a faucet leaking.
Water drips from hose connected to faucet.
Over the last week we have noticed an anomalous peak in the amplitude spectrum of various sensors on ETMX-ISI, reminiscent of the 0.6Hz peak on HAM 2(?) back when
Looking more closely it seems to be mostly showing up on a few of the CPS channels, St1-H1, ST2-H2 and H3, see the attached screen shot. This data is with the loops on
A little documentation, first(only?) plot shows all five sets of ISI sensors and which channels show the 0.085Hz peaks (a close comparison show that they some channels behave differently from the previous plot)
The second plot is with the ISI in damping only, and the 85mHz peak is gone, not really sure what to say
While looking for something else, I noticed that
ETMY had a similar feature at 0.7 Hz in Aug 2016. Jim and Jeff did some work on it.
see alog 28960.
Not sure if we resolved that one, but maybe it is interesting. I log it here so I don't forget.
Never mind - the previous issue was with a Trans Mon Suspension which had been left undamped and caused a feature at about 0.73 Hz. This feature is at 0.085 Hz, not 0.85, so is not related.
