JimW, RickS
After swapping out the Pcal barrel baffle button-head screws, we checked the alignment of the Pcal beams at the Rx module power sensor.
With the ETM aligned within 50 urad of the nominal location (see attached photo), the Pcal spots were where we expected them to be (see attached photo). Good news.
JimW, RickS
Last Friday, we swapped out the 48 electro-polished 1/4"-20 button-head screws screws that attach the "barrel" baffles for screws that had been coated to reduce reflectivity. We also swapped out the washers for coated washers.
Note that the heads of the coated screws are deeply stamped with letters and numbers, while the electro-polished units are smooth.
Chandra R. has been notified that I am here. I expect to be here < 2 hrs. doing various checks of the purge-air supplies at the end stations and the corner station, NEG bake in LVEA, VBO C in VPW and CP4 bake in the Y-mid VEA. I'll make a comment to this entry when I leave.
Turned off YBM MTP controller and GV5 AIP controller. Kobelco oil temp running a little warmer than previous 6 months at 105F. Found flange bolt within Kobelco has worked its way loose and has fallen out. Flange in question is too hot to work on while running but this can be dealt with on a maintenance day. Moved RGA laptop from CP4 at Y-mid to VBOC in VPW (we need to install RGA software on a second laptop at some point). Also, I isolated the scroll pump from Turbo at CP4 and used room air to purge scroll stages of any forming water condensate before restoring to as found configuration. During this visit, I started the last 90 minute activation of the final NEG pump on the OMC tube as part of the particulate mitigation exercise. As such, I'll be able to vent this NEG and do the last UHP N2 blow out anytime tomorrow and be done with this extra step applied to the three vertically oriented NEG pumps. 1955 hrs. local -> Leaving site now.
Today Richard M. tested the new (borrowed) SCR that Kyle installed last night on CP4's regen control circuit. It tested fine and then shorted after about an hour with GN2 flow. I was conservative in driving it while ramping temperature. We are not sure of the exact cause of failure, but are convinced it's an overheating issue. We might install one of the larger HVAC SCRs or buy a 16A variable transformer to control the heater.
Kyle, Chandra, Mark D. Tyler
A new/rebuilt large ion pump was tested at high volts: 114 uA at 7000 V. Monday morning we will vent it with N2 and then install on the new valve on YBM.
Mark and Tyler spent the morning torquing bolts and maneuvering IP equipment.
Starting pumping the XBM today. QDP80 is currently valved out with pressure at 45 Torr. Will resume on Monday. Blow down measured -15degC dew point.
Before pump down I replaced PT-170 full range gauge on BSC7 with a brand new gauge. PT-170 and PT-180 have been acting strange, and after some conversations with manufacturer, we agreed to send at least one unit back for contamination analysis.
1345 hrs. local, Saturday PT170 showing XBM vented. New gauge?
Chandra on site 7:30 pm to 9 pm local
I came on site to check this out. I found that the new IP6 valve flange to beam tube was improperly torqued with a large leak to XBM volume. I also found the gate valve not fully closed (not cammed over).
Reconnected purge air to XBM and slightly opened IP6 gate valve to allow flow path for flushing to dry out the volume. We'll check the blow down dew point on Monday.
Jim, TJ, Cheryl, Patrick 13:50 UTC Peter to PSL 14:50 UTC Mark and Tyler to LVEA (moving HAM6 door) 18:02 UTC Chandra to mid Y 18:02 UTC Travis, Sebastian, Terra, Slawek to end Y 18:14 UTC Karen to mid Y and end Y to drop off supplies 18:38 UTC Betsy to end Y 19:20 UTC Peter to PSL 20:42 UTC Peter and Ed out of PSL 21:08 UTC Tyler done at IP5 21:17 UTC Peter to PSL 22:36 UTC Peter out of PSL 22:56 UTC Tour offsite
Slawek, Sebastien, Travis, Betsy, Terra
All done with AMD installation at EY, we removed the installation jig this morning. See pictures of the 4 AMDs attached.
Ronaldas, Sheila, Corey 'H1_01_january/04_april/08_august.jpg' shows how SRM angle changes over O2 run. One can see that SRM P angle changes its relative position from about -40 (January) to -110 (August) in microrads. SRM Y angle changes over time not that much, just from 880 (January) to 860 (August) in microrads. Using distance measurements by Corey (attached as 'dist_meas_Corey.png'), maximum angle change is only 70microrads * 2100mm = 0.147 over the period of 8 months. Sheila suggested that this change in angle is sufficiently small to ignore. For a comparison, Livingston January SRM P/Y angle change over time is attached. L1 angle change is a bit bigger but still relatively small. About plots: 1) data is plotted only when IFO is locked (this explains sudden jumps in angle values); 2) each plot has the total duration of '15 days - time when IFO was not locked'; 3) data was taken from the following O2 dates: 10-25th of January, 10-25 of April, 10-25 of August. Plots are attached to the aLOG. Code used to get data and generate plots is given as well.
This morning TJ unlocked the OPO, and I tried taking some L2L TFs. First time I've tried taking SUS TFs, so I'm sure it could be done better. Not sure what to make of these either. Looking at the little cartoon on the OPO overview would lead me to believe that each corner should look kind of similar, but to my eyes they don't. TJ also thinks the OPO could be balanced a little better, so maybe the weird cross transfer functions are a result of some rubbing? Mostly I was looking for an obvious miswiring, I don't see anything that screams that, yet.
Bypass will expire:
Mon Apr 2 09:22:21 PDT 2018
For channel(s):
H0:VAC-MY_CP4_253_REGEN_TEMP_ALRM_INTLK
Chandra had attempted to use the newly installed submersion heater unit (borrowed from CP3) using the existing SCR but continued to experience the "SCR SHORTED" trip. This SCR had failed when used with the original submersion heater and may have been damaged then. So, I borrowed a "virgin" SCR from CP6's regeneration control panel and installed it in CP4's control panel this evening. We will review the schematic and SCR manual etc. and consult Richard M. before are next regeneration attempt so as to "put our heads together" in an effort to understand why these SCR units are failing.
Completed particulate mitigation exercise on the second of the the three NEG pumps mounted atop the OMC tube. I will move the associated hardware to the third pump tomorrow and hope to make headway on it.
Today, we performed a few iterations of weld annealing with the goal of reducing the differential pitch offset of the PUM-to-ETM from the initial welded value of ~3mRad. After 2 iterations, we had the pitch down to ~1.6 mRad. As we were preparing to break for lunch, I noticed that the PUM prism crack (referenced in aLog 41111) seemed to have grown from what I recalled. During the break, I looked at Betsy's pictures that were taken shortly after removal from chamber which confirmed my suspicions that the crack had increased in length. We decided this warranted a discussion with several of the decision making staff (Dennis, Peter, Calum, Fred, and Garilynn). Together we concluded that it was probably fine to carry on since the crack only seemed to lengthen when exposed to heat from welding (the initial cause of the crack and the cause of this case of extension) and that this side of the PUM would not need to see any more heat for the annealing that was continuing. (Note that the copper prism shield that was designed to protect this from happening again after the first instance WAS installed, but apparently enough radiative heat was present to affect the crack anyways.) We continued on with another iteration of annealing which resulted in a final differential pitch of ~350 µRad. This concludes the final post-O2 monolithic welding session. Check.
Attached are the pictures of the crack from today along with the 2013 and extraction PDF of pictures for comparison.
Note, we did discuss various options such as adding or wicking epoxy or silicate bonding solution into the crack. However, looking closer at the various viscosity properties of each and a previous attempt at this at LHO, we decided it was likely not to help the situation. We also are not convinced this will be a problem for us. We will however mobilize to prepare a spare PUM for the next time around.
Final alignment numbers for the ETMx fiber weld. All measurements were done with the ETMx suspended; the PUM and UIM were both locked. All numbers assume the reader is looking in the -X direction (i.e. at the AR surface of the ETMx); this is opposite the notation used in the alignment notebook, which is done from the perspective of the alignment equipment (i.e. looking at the HR surface of the ETMx). All measurements (except the pre-welding roll) were done after yesterday's correction of the differential pitch; before the correction the differential pitch was 3.13 mrad down. In addition, I have also included before and after welding numbers for the roll of both the PUM and ETMx, as there was a change in roll somewhere during the welding process that needs to be documented.
We're not entirely sure why the roll changed during the welding process, especially as much as it did. The going theory is that when the ETMx was hung it pulled on the PUM, causing the observed roll issue. Maybe a small mechanical misalignment between the PUM and ETMx (my guess is possibly a horizontal position offset between the 2 masses; this is something we do not measure with the IAS alignment equipment, so I have no numbers to back this up) caused a shift of the ETMx relative to the PUM during the hang which pulled on the PUM and caused the roll change (this is just a guess on my part). The differential pitch correction work did not have an effect on the roll of either mass, as the roll measured after the correction was identical to that measured before the correction. I don't recall seeing an issue like this with any of our previous welds at LHO, either during this post-O2 vent work or during aLIGO install. It should also be noted that this roll error is a contributor to the difference in measured fiber stretch between the left and right side of the monolithic.
The serial numbers of the fibers used and their location in the monolithic are as follows:
I'd like to thank Chris Sioke for his help in lugging the alignment equipment to the end station Monday morning, and Stephen Appert for his help in getting everything set up. You both made things go quicker than if I were doing it all myself.
pictures of fibre ends and welds taken after destress before initial hang - that is before the post-hang annealing to correct the pitch offset, These are the ETM welds
and these are the PUM
Shelia, TVo, Nutsinee, Alexei, Dan
Today we continued trying to align the beam into HAM6. The beam going into HAM6 leaking from the OFI was ~15mm too low on the SQZ apertures. To try and correct this we adjusted SR2 and SR3 pitch within the ranges we found yesterday (alog 41197) to avoid any OFI clipping. We were unable to find a suitable alignment that avoided the OFI clipping and pitched the beam up enough to make it through the center of the SQZ apertures.
The procedure was:
| SR3 slider value | SR2 aperture clipping points | Vertical offset as SQZ aperture (mm) |
| 500 | 270 and 620 | -17 |
| 600 | -540 and -70 | -12 |
| 800 | -1900 and -1480 | -10 |
| 1000 | -3290 and 2930 | -7 |
SR3 pitch of 1100 was causing clipping yesterday so we stopped here. We tried to improve on -7mm by pitching ZM2 but this railed before being able to sufficiently correct it. The beam going into HAM6 had an angle of 7mrad toward the SQZ aperture (The beam dropped ~5mm over ~68.6cm) which is too much for ZM2.
Shelia and Terry have gone back into HAM6 to look at alignment further.
We measured 5.5mW of light arriving in HAM6 heading towards the OMC in single bounce, and 3.4+/-0.1 uW arriving in HAM6 in the squeezer path, so the rejection ratio of the thin film polarizer at the output of the OFI is about 1600:1.
After the exercise that Daniel described above, we let SR3 pit at 600 on the slider (cage servo off), and 490 yaw, SR2 at -240.8 urad pitch, 3705 yaw, and zeroed the offsets on ZM2. Terry and I attempted to align the squeezer to this beam, to see if we can get in some measurements of the mode matching from the squeezer to the OMC before the HAM5 vent next week. In the end we didn't find the beam, but we have left ZM1 pitched with the adjustment screw most of the way in. We will undo this soon, so there is no need to re-center osems or worry about rubbing.
Slawek, Betsy, Sebastien, Georgia
We finished installing the remaining AMDs (AMD 3 and 4) on ETMY this morning. Everything went smoothly, no issue to report. The required force was applied and we observe a nice ring of epoxy around the AMD bases, as expected. The epoxy has to cure 24h with the jig in place (we will remove it tomorrow).
We also inspected AMD1 and 2, installed two days ago. Bond looks uniform, as we observe few fringes between the base and the test mass (Betsy will put pictures later). Find attached a little sketch (not to scale) showing the rough locations of the AMDs on the flats. We will have more precise numbers by looking at the pictures.
Following are pictures of AMD 1 and AMD 4 installed.
And below are pictures of the AMD 2 and 3 installed this week.
Well done team! Nice easy install.
I have measured the dust counts just outside of the chamber and inside of the BSC10 chamber a few times throughout the install of these on Tuesday and today - in all cases, the numbers have been less than 30 for all sizes of particle.
So have had a continuous exponential spectra of the WHAM6 CPS signals running on the desktop watching for the grounding or whatever-it-is noise on the Corner3 sensors. The attached snap shows this new noise. The reference and the thicker traces are the corner3 signals, which look fine. The other four fine traces are the corners 1 & 2 signals. This isn't even the worse of it but it looks very similar to the corner3 noise seen previously while messing with the cabling there the last few days. Note that the corner3 channels are in one satellite crate and corners 1 & 3 are in the other. I'm suspicious activity around the chamber has disturbed the ground of that crate and made it iffy.
I went back to about 1pm yesterday (1900 utc 28 March) and watched the spectra until it went noisy like this. First time I spotted was 0130 pdt this morning. Will check with EE to see if they know of anything.
This noise has come and gone since starting and wouldn't bee too worried about it if it was associated always with activity near by the satellite crate but as it started in the wee hours...
Haven't been staring at this all day but haven't seen this noise pop up again all day. Haven't looked at crate or talked with EE. Will comment tomorrow.
Got a typo in the main (can't edit anymore): "...the corner3 channels are in one satellite crate and corners 1 & 3 are in the other." should be corners 1 & 2 are in the other.
Sorry for confusion. Still haven't made it out to the box to inspect but I haven't noticed any problem with the spectra either since ~9am yesterday.
