The old Balzers RGA mounted at YEND was powered down and valved out today to facilitate electrical work. This RGA was valved into the system ~June 8 by Kyle and I.
NOTE - this is NOT Rai's RGA - it was not disturbed.
Attached are plots of dust counts > .5 microns in particles per cubic foot.
I have uploaded a brief report on efforts to understand and diagonalize the OSEM sensor readouts on the two quadruple suspensions at LHO. The BSC8 chamber containing ITMY is now out of vacuum and so further testing on it will not be possible for the near future. The ETMY will still be under vacuum and is amenable to more testing that should help us understand how to fix the responses of the lower stages of the quad suspension OSEMs.
https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?.submit=Number&docid=t1200442&version=
EricA Hugh & Apollo JimP & Keith We throttled down the Pump Station operating press to 30psi, then move the BSC8 4-way valves to bypass isolating the Actuators at the Chamber. We then put the Pump Station System up on the Mechanical Room Mezzanine into recirculate mode. Then the 1-1/2" supply lines in the LVEA were closed. With pans and pitchers in place, we started opening up the drain and vent ports. With a little additional help from some bottled gas in the vent port we have pretty much emptied the system. All the port are closed for the night. We'll let the fluid pool overnight--there is a lot of shallow sloped tube. In the morning we'll dump the final bit that accumulates overnight and then start taking out the temporary lines.
Started assembling BSC#4's lockers today and encountered a rather annoying issue, which, I vaguely recall, we may have run into before. When inserting the Stage 1-2 locker sleeves (D1000875) into the locker housing (D1000908) I could thread the sleeve down into the housing, but couldn't get it down the last 1/4 inch. I suspect that there is some manufacturing issue with the sleeve, because I had no such difficulties with the Stage 0-1 parts, which use the same housing. The sleeve does have very tight tolerances to the housing, so a small error in concentricity would totally screw this up. There are a couple of pretty easy fixes for this (lathe the interfering part down, or electropolish a couple tenths off) but the sleeve is coated with a anti-friction treatment, which will need to be re-applied and thus slow down re-processing after the fix. I was able to find enough sleeves that happened to work (3 out of 7 tried) to keep BSC#4 moving, but this job took 3 times as long as it should have. Otherwise BSC#4 is going well, the superstructure is assembled and is now waiting to be populated with sensors, springs, lockers, etc. We are also slowly working towards getting the other staging building test stand converted so we can start on #5, whose Stage 0 plates are currently waiting on the floor for some free table space.
Wipe down started this morning.
We moved the green iLIGO cleanroom from the HAM6 Laser Bay so that we could use it on the E Module at BSC8. I also worked on the cleanroom curtains.
This morning, Bubba and I moved three optic table enclosures from the LEA to the LVEA. One went to the HAM6 Laser Bay and two will be craned over into the West Bay for dis-assembly and storage since they are destined for LIGO India. This afternoon, Bubba fired up Big Red and moved the BSC ISI from Y-mid to the LEA.
Attached are plots of dust counts > .5 microns in particles per cubic foot.
The bug has been fixed, so I've reinstalled new gds tools for Ubuntu workstations. Mac OS X to follow in the morning. See note from earlier today describing changes.
Something is causing the iLIGO HAM1 Optical Table to be too low. First I measured the weights of the masses I'm using for the payload. A drawing error has me 11.254lbs heavy; I don't think this is enough to make a large effect. D080001 & 2, HAM Trim Mass Large & Small have their weights noted in lbs; looks to me they should have been Kg. So D080001 is noted to be 1.14lb, I measured 1.106kg; D080002 is noted to be 0.26lbs, I measured 0.25kg. I'll put redlines in the DCC. The Spacer D1200530 (between Support Tubes and Support Table) measured as drawn as I remember Mitchell confirming when we received these. I measured the Gap between the two Leg Elements (large masses in the isolation stack) in a few places to measure the compressed height of the Spring. This value is 1.86+-0.01". I did not measure an uncompressed Spring. T1000310 (PeterF's HAM1 Isolation Stack doc) notes a 2.03" tall Spring with 0.14" of compression. So about 3/4mm more compression (still early days too) x 3 for the three layers of Springs in the system. So, this would put us 2.5mm low...OK not enough there. Sam Barnum of MIT reports to me the compressed Spring height in the model (used to determine the Spacer height?) is 1.93" putting us 5.25mm (over 3 layers) lower than expected.... So I don't see enough from these listed issues to get us to 15mm, maybe 6mm low... Other possibilities are the leg elements and Optical Table are heavier than modeled...maybe I can put some numbers on that soon.
JimW, HugoP,
We recently huddle-tested the T240s received in LLO's shipment #4386. We took power specra that look fine. We also checked the pressure readouts which appeared surprisingly low: ~40kPa instead of the usual ~100kPa.
We investigated this issue and found that it was caused by a model discrepancy at X1, which does not match what is installed at ETMY and ITMY (see attached screenshots of the models: X1, ETMY, ITMY).
Pressure signal processing at X1: Pressure_Displayed
Pressure signal processing at ETMY/ITMY: Pressure_Displayed
If we reverse the processing applied at X1, and then apply the one of ETMY/ITMY we then obtain:
( 40kPa / 2.879e-3 * 5.065e-3) + 30.625 = 101 kPa
... Which is what we expected in the first place. The four T240 pods received in shipment #4386 were huddle-tested OK at recption. Results are available under the seismic SVN.
Other measurements performed during the investigation, at X1:
-We read 0 kPa when nothing is plugged into the T240 interface
-We read ~40 kPa with the T240s are plugged in
-We measured 8.36V at the T240 interface (D1002696) "to-Anti-Alias" output
-The power supplied to the T240 interface is:
-17.96V
+17.75V
Today marked the official end of the 1-Arm Test (laser powered down at EY [laser safe there now], venting of Y-Beam Manifold, etc.)
MC3 has all 6 top BOSEMs plugged in and backed off in prep for new OLVs and gain settings. As well, we've attempted to fix the side BOSEM flag cross coupling - we indeed found the flag to be mounted quite crocked and have straightened it. TFs will tell us if the cross-coupling is alleviated.
While rechecking the open light voltage offsets on the MC3 INMONs, I noticed that the T2 BOSEM gain was set to 1.405 (likely instead of 1.045). Possibly this is what was causing heart ache during the testing phase immediately after the build across the street in the staging building on this sus. The gain should now be set to 1.049 since I remeasured with the sus on the production cables/electronics. Attached is a snapshot of the inmon setting before my work today.
And the new settings from today snapshotted below - mostly small number tweeks except for the T2 gain noted above.
The burt restore file to be used should be the cds auto one at:
/ligo/cds/lho/h1/burt/2012/09/18/17:00/h1susmc3epics.snap
There was a transverse to yaw cross coupling noted in the TFs for H1-PRM (orange trace). To isolate the problem we moved the side BOSEM to the other side of the suspension and re-tested. With the BOSEM on the opposite side, the cross coupling disappeared (black trace). Before moving the BOSEM back to its correct side position, I found the magnet/flag base to be misaligned. This was corrected and the BOSEM was re-centered to 50% light. Subsequent testing shows the cross coupling has been removed (purple trace). H1-MC3 and H1-PR2 also show the same cross coupling. We will check the side magnet/flag base alignment on these two suspensions and re-align as necessary.
[Stuart A, Jeff K and Jeff B] Adjustment of the PRM (HSTS) side flag mounts rectified the Y to T cross coupling observed in previous measurements. But something else appears to have cropped up. The plots below (allhstss_2012-09-19_0940_All_Phase1b_PRMs_ALL_ZOOMED_TFs.pdf) show a comparison between the latest two complete data sets of un-damped M1-M1 TFs, with the most recent being the orange trace. It can be seen that these recent TFs exhibit signs off:- - Roll (slide 4) looks to show stronger vertical mode coupling at ~0.85Hz - Pitch (slide 5) looks to show stronger vertical mode coupling at ~0.85Hz Most likely, these are sensor-related cross couplings -- as in the usual imperfect subtraction of common mode signal (Vertical) in the differential signals (Roll and Pitch). But they were not so apparent in the 2012−09−06_2000 data, and we wish to be sure that they are not related to the re-alignment carried out on PRM to rectify the Y to T cross coupling. To demonstrate the significane of these Pitch and Roll cross couplings, we provide a plot showing similar couplings for ALL HSTSs from both sites (allhstss_2012-09-19_1040_All_Phase1b_HSTSs_ALL_ZOOMED_TFs.pdf). This demonstrates that compared to other HSTSs the feature in pitch (again the orange trace) is less of a concern. However, the feature in roll could be considered egregious. It should be noted that the most recent PRM TFs were taken during the middle of an active day. Therefore, the next data will be taken at a quieter time, when the common mode (Vertical) signal is reduced (or by just turning on the Vertical damping loops while taking the Pitch and Roll measurements with loops open). All plots and scripts have been committed to the sus SVN as of this entry.
