Betsy and Sheila are transitioning the LVEA to laser hazard. They plan to run it overnight and into tomorrow, but can transition back if someone needs it.
After Betsy's observation that a wrong beam might have been used for EY oplev (alog 40653), she and Georgia went into the chamber and faked the "correct" EY alignment by pushing the optic using EQ stops until the right beam is on oplev. It's not quite centered but it's not very far. The OPLEV SUM dropped to about 11k.
After this we turned on the ALS laser, and got retro-reflection well within the adjustment range of TMS OSEM. It seems like Betsy found the right beam for EY oplev.
When the REFL was on ALS REFL PD, TMS sliders were P=-88 urad, Y=-168 urad (full range is +-298 for P, +-608 for Y).
Rick and Travis are going back to EY to see if this EY angle is also better for PCAL. IF that's the case EY needs to be properly realigned (not faked by EQ stops but by adjusting the cage etc.).
TravisS, RickS
We switched on the Pcal laser and checked the alignment of the two Pcal beams into the Rx module integrating sphere.
Both beams were reasonably well centered. They were slightly offset from eachother vertically, but only by about 1-2 mm and they were very close to the center of the Rx integrating sphere aperture.
It seems that work on the periscope structure DID NOT impact the Pcal alignment significantly (GREAT NEWS!).
Keita has transitioned EY to laser hazard.
-Niko
EY is now LASER SAFE
7 weeks of BRSX and BRSY driftmon channels. BRSX is below between 2017-12-28 and 2018-01-04, and above between 2018-02-01 and 2018-02-15. BRSY is within boundaries.
Pressure will rise at CP4 PT-245 while the turbo is valved out again today.
Jim Warner, Georgia Mansell, Sheila Dwyer
This morning we went back to EY to make some follow up measurements with the electric field meter that Rai brought. (40599 and 40597). Our main result was to confirm that below 300 Hz the measurements we made on Monday were dominated by acoustic noise from the purge air and clean room, and that some care should be taken to mount the meter so that it has some isolation from acoustic noise and ground motion. It also seems like the line we identified as being from the CPSs on Monday is not actually the CPS line, and we are not currently seeing any signal from the CPSs in the field meter.
Today the field meter was oriented to measure fields parallel to the beam direction and we did not rotate it. We first repeated the measurement we did on Monday with the cleanrooms and purge air on. We then turned off the cleanroom over the BSC chamber (leaving the others alone) and repeated the measurement, then repeated it with the purge air also turned off (top panel of attached plot). We saw that a line at 33.8kHz was coming from the cleanrooms, and that the noise below 300 Hz was driven both by the cleanroom and purge air motion, as we suspected on Monday after seeing that the spectrum didn't change when we added a tin foil Faraday cage.
We made a single measurement where we attempted to turn off many of the expected sources of fields in the chamber.
We repeated the measurement with the clean room and purge air off and saw that powering off all of these items didn't make a difference in our spectrum (bottom panel of attached plot). To confirm that we had really turned of the CPSs, Jim unplugged one of the cables from the CPS interface that is a silver chassis on the cable tray, no error light lit up when he did this.
Hugh looked up for us the frequency of the CPS clock signal, which is 25.725kHz. The second attachment shows the spectra zoomed in around 25kHz, and you can see that the line we see is at 24.8kHz, so it may be due to something other than the CPSs.
We will take a break from making these measurements for a few days while the end station alignment work is going on, but if we have an opportunity Rai has requested that we try the measurement with the neutral pin of the power supply grounded to the box and floating. If possible we would also like to mount the meter so that it is held off of the bench and has some vibration isolation.
Framing is erected and most of the insulation pads are up. Need to work out some bugs in the electrical. Reworked a few areas of strut interference. Designer will create as-built drawings. Thanks everyone for your help today: Ken, Mark, Richard. Tomorrow we resume.
We have an adapter cable to swap CP4's pressure reading from PT-245B to the {temporary} full range hot cathode gauge installed on turbo inlet, since we'll lose PT-245B (electronics) in the heat. Patrick T. is working on software code for this swap. Thanks!
After hearing that both the TMS and PCAL beam alignments did not recover after we swapped the ETMY and aligned it to the OPLEV, I did some brainstorming with Daniel, Sheila, and Keita who were in the CR. A few trends of OPLEV data later, and I'm thinking that Travis and I have aligned the ETMY to the incorrect OPLEV beam.
There are 4 red beams heading towards the ETMY OPLEV receiver, of which Travis and I convinced ourselves that we understood the second from the bottom to be the main reflection beam based on the wedge orientation (it's also the brightest, which maybe doesn't matter based on the coating). Even if this is the correct OPLEV beam, it is not obvious that this was the beam that was used for the "before" alignment of the ETM. However, a quick look at the trend attached shows that the SUM of the OPLEV was much lower than it is now prior to the test mass swap, maybe arguing that we've got the wrong beam.
Tomorrow we will point one of the other 2 possible beams onto the OPLEV and see if the PCAL and TMS pointing are restored.
We went in the EY chamber and saw that the return beam was off on the secondary mirror at 1:30 position, the radial distance from the forward going beam was maybe 5 or 6mm. The return beam was not even hitting the bottom periscope mirror under the TMS optics table.
We steered TMS suspension as much as we could using the bias slider and it was clear that we need at least twice the range for YAW, more for PIT. We need positive PIT and YAW, both at around a milliradian. That's huge misalignment.
This cannot be ring ERM as the original ERM was wedge-less.
The wedge of the new ETM is somewhat different (old one was 0.076 deg, new one 0.07, the difference is 0.006 deg or 100 urad), and this is not large enough to cause milliradian difference.
We checked apparent interference but we couldn't do a thorough job.
We installed kapton washers to the picos, but we haven't installed collars as it will change the TMS balance (we will NOT fix the lack of collars as there's no need for gross motion of picos at this point).
FAMIS 6563 Added 100 mL H2O to the H1 PSL crystal chiller. The lower left canister filter is discolored. The top right canister filter is white and clear of debris. The fault light on the diode chiller is not lit.
Discoloration in the Crystal Chiller filter is due to the 70w install. The filter is downstream from the new amp and supporting plumbing and caught the gunk from them. Will swap in a new filter when the PSL work is finished.
Bubba, Gerardo, Kyle We removed BSC1's North Door for Betsy W. and re-installed after she completed her in-chamber work. We are pumping BSC1's annulus with a small turbo backed by a leak detector overnight. We expect to helium leak test the door in the morning followed by submission of a WP to pump down the Vertex Volume.
Torqued the two flanges that were removed, F2-3 and F3-1. Leak testing needs to be done for both.
Maik F, Jeff B, Jason O, Peter K, Matt H
Quick summary of recent tasks:
In prep for removing the BSC1 door, I turned to OFF, and then removed the keys to the TCS lasers in the LVEA.
After we were finished putting the door back on yesterday I put the keys back in the TCS power supplies and turned them back on. Beam blocks have been in place on the table for a few weeks mow however so this was just extra caution.
While closing out the recently replaced SUS ITMY R0 RT OSEM (alog 40634), found short on UIM chain. Short is on cable SUS_ITMY_16, pin 5, cathode side of LED for UIM UR.
Sheila and Kissel have confirmed that this UIM UR LED is not used (and would be a much larger scope to fix). So, we have opted to save this fix for a future fix. Attached shows the spectrum of all of the L1 and L2 stage OSEMs for ITMY - you can see the elevated noise on the black L1 UR trace.
Summary: The core functionality of the Matlab DARM model has now been replicated in Python. Attached are figures in a single PDF file showing the primary results. By eye, these look reasonable. A more detailed study comparing to the Matlab model is forthcoming. I also replicated a study made for the L1 detector by Joe B. (see LLO aLOG 29622). I propose to call this code pyDARM. Details: I have ported most of the core functionality of the DARM model from Matlab into Python. So far, I have done spot checks by eye to make sure that the results look sensible. I have not yet done a detailed study comparing to the Matlab version, but will do so soon. I have produced plots showing: 1) DARM digital filters 2) Sensing function 3) Actuation function 4) Open loop gain 5) Frequency dependent actuation authority of each stage compared to inverse sensing 6) Ratio of each stage to the overall calibration As can be observed, the scale of each figure appears reasonable (comparing with, e.g., G1700316), the OLG is stable, and with a UGF with the correct value (by eye). The contribution of each suspension stage is closely matching L1's results using the Matlab model (see LLO aLOG 29622). What was done: - Write python version of Matlab functions to parse Foton filter files and to compute IOP downsampling filters from RCG code coefficients - Exported numerical values of zeros, poles, gain, delay from analog AA and AI models (these are objects in .mat files) - Exported ASCII file of the frequency response for the suspension force-to-length for each stage. This is read in and used in the python DARM model, and so far can only be at specific frequency points - DARM filter bank digital filters computed, sensing function and actuation functions are computed from parameters - Intermediary data products can be accessed - Code structure is "flatter", meaning less jumps between different functions/files. Hopefully this makes the code more accessible and readable. Required python modules (so far): scipy (e.g., filters), numpy (e.g., arrays/array math), collections (for namedtuples), matplotlib (for plotting) Quirks found along the way: - You can't directly multiply or add filter objects together in Python (the + and * functions are not overloaded in Python). I had to code up my own version to 1) add filters by using polynomials from roots, computing a transfer function filter, and then converting to a zpk object, all using scipy built-in functions; and 2) multiply filters by appending zeros together, poles together, and multiplying gain. - The scipy sos2zpk() function is not exactly like Matlab's version. I found an extra zero and pole when converting because Matlab removes any zeros in the 3rd and 6th positions of an sos section before computing a filter from the sos coefficients To do list (short term): - More detailed study comparing Python with Matlab models - Read in a config file - Make an L1 model to check for any differences - See if there is a way to read Matlab .mat file and objects therein. This didn't look trivial when I tried at first, which is why the analog AA and AI models were exported as well as the frequency response of each suspension stage - Address how to get the force-to-length transfer function for each stage for arbitrary frequencies - Add computations for GDS / DCS pipelines Longer term: - Hook this into a pipeline from measurement to model to uncertainty estimate pipeline
Attached is an updated figure to include the inverse sensing contribution ratio to the overall calibration. Observe that the inverse sensing has impact on the overall calibration above ~10 Hz.
Evan, this looks great, but I don't see any links to the actual pyDARM code? Can you push that to a git repository somewhere? I would be happy to help with python packaging if needed so that this is trivially distributable.
