jodi.fauver@LIGO.ORG - posted 12:40, Tuesday 18 September 2012 (4235)
BSC9 ICC
All brushing was completed this morning. First vacuum was completed this afternoon and wipe-down got started.
All brushing was completed this morning. First vacuum was completed this afternoon and wipe-down got started.
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.
Christina and Karen will do a gross cleaning of the uncovered Test Stand and vicinity this morning. That should give us some idea of how many cleanings will be required to get things into reasonable shape to receive the cartridge.
Phase 1 Cleaning of the HAM cleanroom is complete and signage posted.
There appears to be a favorable slope change starting ~ Aug 8 (65 days on this log/log plot) Browsing the aLOG I find that near that time there were ring heater operations, and one week prior to this Kyle disconnected a small turbo pumping the BSC6 annulus. I don't think either of these explain the slope change. I also looked at the big ion pump voltages during this period - there were no step changes anywhere near this time.
GV18 was cycled on August 7-8 -Rai might have been making RGA measurements?
John, You are correct I was making measuremants and moving the gate valve on both August 7 and 8. It seems that the slope became 1/t after the measurements. It is not easy to understand this. The first thought would have been a leak in the valve between the RGA and the chamber with a poor vacuum in the RGA. This is not the case as the 2 liter/sec ion pump was holding the pressure in the RGA volume below that in the chamber. Another possibility is that the annulus system was leaking but you rule this out from Kyle's measurements. I am stumped. RW
Kyle decoupled the annulus turbo pump on July 31 - probably not this.
A signal we do not yet have is the BSC 6 annulus ion pump current as this chamber and it's pump were brought from the mid station. - I'll ask Dave about this.
Kyle recalls that he disconnected the annulus turbo pump for noise reasons at the request of Robert rather than for vacuum reasons. Some days later he was surprised to find that the annulus ion pump had "come on scale" as if the pressure had fallen in the annulus space to the point where the ion pump could start.
This suggests that there may be an inner oring leak from the annulus to the BSC6 chamber which might explain the slope change. Once the annulus ion pump began pumping, this gas load was removed from the chamber.
Richard has our electrician working at connecting up our new annulus ion pumps to the CDS system so that in future we will be able to trend these signals. At the time we did not assign any priority to this work.
A new version of gds software has been installed for Ubuntu and Mac OS X workstations. The notable differences appear in foton and diaggui. Widgets for displaying channel names have been made much wider, forcing the layout of several screens to be changed. Diaggui measurement tab now shows 2 columns of channels instead of 3. Diaggui excitation tab has two channel name widgets for each excitation, the wider length required these to be put on separate lines. The plot options panel on the result tab is also wider to accomodate long names - this affects foton as well. Since the plot options panel is wider, there's less room for the actual plot, but the option panel can be detached so it "floats" which should allow plenty of room for the plot. The Export popup dialog in diaggui also has channel name fields that have been made wider, and there's now an option to add a header to the ASCII export file. The header contains information to allow identification of the source of the data. Complaints should be addressed to me or filed with bugzilla.
I have reverted GDS tools to the previous version, 2.16.3 due to a bug discovered by Hugo.
Measurements to begin at ~9:00 PM PST.
Measurements completed.
Attached are plots of dust counts > .5 microns in particles per cubic foot.
ScottL & HughR Payloaded HAM1 Optical Table per D1200524. This is 310lbs which stays on in place plus 40lbs to substitute for the ISC equipment that will eventually go onto the Table. I've got the Table level to ~+-0.15mm but the elevation is low by 15mm. We'll continue to work this Tuesday.
Hand brushing of the upper chamber was completed this morning. Half of the BSC flooring was stacked to expose half of the lower chamber: both pneumatic and hand brushing were completed on the exposed half. The flooring was replaced and the other half stacked to expose the other side of the lower chamber.
I tagged the four large (pallet-sized) storage units in the West Bay. I replicated the system that Hugh and I worked out for the Mechanical Room storage units, back in the day. The storage units are each assigned a letter, the shelves are numbered, and then the shelves are sub-divided into sections (left, center, right). This should facilitate input of ICS storage locations. When putting info into ICS use the following format for location/sub-location: LVEA/WBSU X-Y-Z where X is the letter assigned to the storage unit (A,B,C,or D), Y is the shelf designation (Floor, 1,2,3,4,or 5), and Z is the shelf sub-division (L,C, or R). For example, I have cleanroom materials on Shelving Unit B, shelf 2, left side so my ICS entry would be: LVEA/WBSU B-2-L.
[Aidan, Jax]
Over the weekend, we ran a final series of cavity scans with the updated ring heater driver. The ETM ring heater was operated at 450 mA/13.2 W from 17:55 PST on Friday Sept 14 until 19:25 PST on Saturday Sept 15. Cavity scans run approximately every 90 seconds over the range [36,76] kHz every 20 Hz. The amplitude and phase respones were averaged over 500 oscillations. Cavity scans were also performed after the ring heater was turned off, but the cavity was unusually noisy so the data in the cool down period is unusable.
The frequency of the LG10 mode was tracked over this 24h period. The attached plot (modal_spacing_analysis_v2_frequency) shows the change in frequency over time. The spacing of the LG10 mode is two times the modal spacing in the cavity.
The modal spacing, cavity g-factor, and mirror radius of curvature were also calculated and plotted. They are attached as _modalspacing, _gfactor, and _radcurv, respectively.
35W beam. The laser room HEPAs, lights, and AC units were turned off and the make up air was set to 50% for these measurements. The anteroom lights and HEPAs were still on.
Pointing file didn't upload, I attached it here.
This was supposed to be posted by me...
(Suresh Doravari, David Jones mainly [& myself a little])
Suresh was onsite for the last two weeks to assemble as many Tip Tilts as he could (Suresh is from LLO, but we have all the hardware here). Each interferometer requires a total of (6) Tip Tilts. As of late Friday (9/14) afternoon, Suresh completed all Tip Tilts for LHO & LLO, and completed 2 (of 6) for India. He wanted to finish all of them, but he was missing some hardware, so he completed the remaining Tip Tilts as much as he could.
We bagged and tagged all of these assemblies on Fri afternoon. I'll be sending him the LLO batch. The LHO batch and other assemblies will be stored in the Staging Bldg Optics Lab in the meantime. Suresh will be back to finish building these assemblies.
Check ResourceSpace for photos of last week's stack installation at HAM1. Thanks to Bubba for pics of the optical table going in.
[Jeff B, Stuart A] Jeff B posted Phase 1b M1-M1 TFs for PRM (HSTS) in LHO aLOG entry 4195. These recent TFs from 2012−09−06_2000, with damping OFF, show a Y to T coupling at 1.1 and 2.05 Hz. This coupling goes away with damping ON, as can be seen in the TFs from 2012-09-10_0900. Jeff K had made some comments regarding the nature of this Y to T cross coupling in LHO aLOG entry 3831, outlining possible scenarios for how it could be caused. As a consequence, it was requested that Jeff B switched the "side" of the SD BOSEM [i.e. +T] to the opposite side of the PRM structure [-T], and accordingly change the sign of the SD BOSEM gain in the OSEM OUTPUT FILTERS, from -1 to +1. Following these changes, repeat TFs were taken Friday afternoon for just the T DOF. A comparison plot showing the TF for the T DOF both before and after swapping the side location of the BOSEM is available below. Pot Key:- Blue Trace = Model Prediction Orange Trace = X1 PRM M1 (2012-09-06_2000) - SD BOSEM on as-built side Black Trace = X1 PRM M1 (2012−09−14_1700) - SD BOSEM on opposite side It can be seen that swapping the side location of the BOSEM appears to have mitigated the Y to T cross coupling! n.b. all data, plots and scripts have been committed to the sus SVN as of this entry.
Andres R. Jeff B. This morning before moving the side BOSEM back to its proper location, I visually realigned the magnet/flag assembly on that side, squaring it to the edge of the Upper Mass Base Plate. We took another transverse transfer function, which shows the cross coupling has disappeared. We are currently taking a full set of un-damped TFs on PRM as a sanity check.
