Kyle, Gerardo, Bubba -> Door Kyle -> Annulus Will begin "rough" pumping X-end first thing Monday morning
F. Matichard, H. Radkins, J. Warner, K. Venkateswara
Due to the problems described in 15690, Z sensor correction to the corner station BSC HEPIs was causing excess tilts at low frequencies. Based on directions from Fabrice, Hugh and I ran tilt decoupling measurements described in 15726 and fixed this to some extent. The pdf attachment (BS_HEPI_Tilt_Decoupling.pdf) shows the effect of the tilt decoupling at the Beamsplitter. The measurements show the X, Y CPS signals with no sensor correction, with sensor correction and finally with sensor correciton and tilt decoupling. There is still room for improvement and a more careful and longer measurement might reduce this further.
For the moment this seems to be good enough to keep MICH locked with perhaps some improvement in the MICH_OUT as seen in the image attached (MICH_OUT.png). The benefit of the Z sensor correction can be seen in the second image (BS_Zsensor_Correction.png). The improvement is not as significant as some of the other chambers. We should investigate more to see what limits the subtraction.
Edit: I made a mistake in the labeling of the lines. The blue and green labels are switched and so are the blue/cyan and pink labels. In summary, the sensor correction increased x and y motion by a factor of ~10 and ~40 respectively and tilt decoupling reduced it by a factor of ~3 and ~8. A more careful/longer approach may reduce it to the original levels.
I attach a screen shot of
(1) The tilt-decoupling, IPS Align elements that have been installed for the three BSC chambers
(2) The current, raw IPS position position values for these chambers
(3) The current alignment offsets stored on HEPI
Remember that we're concerned that if the IPS raw position values, (2), reach the edge of their linear range (around +/-25000 = +/-2.5e4 [ct]), then the tilt decoupling numbers could change. However, with the current set points / alignment offsets stored on HEPI, (3), the raw IPS values, (2), are at worst less than +/-14000 (most less than +/-6000), well within the linear range, so we expect the tilt decoupling values (1) to be static and valid.
And just for ease of parsing later, if they get lost in a reboot or something, the alignment decoupling values are
ITMX BS ITMY
RX to Z (none) -0.0172 -0.0049
RY to Z 0.0015 0.0038 (none)
Betsy, Travis, Jason, Rick First Contact was peeled from the ETM surface this morning. No First Contact remnants were observed on the surface. Particulate counts, using the "Green Lantern," were in the 2-5 particles per square inch range, down from the 5-10 particles per square inch seen before applying the first contact. The composite image attached below contains six images. The upper row of three were taken before applying the First Contact and the lower row of three were taken after the First Contact was removed. For all images, the surface of the ETM was illuminated with a green LED flashlight. For the four images on the left the flashlight was held by hand. For the two in the right, the flashlight was set in the Arm Cavity Baffle in an effort to make the illumination the same for both images.
Adding to Rick's alog above, we are not sure we see much change in the particulate as observed via the pcal camera with flashlight illumination. We did see some improvement of the particle counts when we counted using the green lantern (lights up across the surface). We blew the optic HR surface for ~10 minutes and did not see much particulate move off.
Particle counts:
We appeared to see more particulate in this chamber than in BSC10 - we noted about 2 times the amount of particles floating through the flashlight beam than in with the ETMy. However, the particle counter counted 0 counts in all sizes when I sampled before we entered the chamber, so it must all be from moving around. We counted the following just after applying FC to the ETMx and while wiping our way out of the chamber
1090 0.3um
560 0.5um
400 0.7um
260 1.0um
Chamber closeout order:
Pulled FC
Blew optic with dei N2 Top Gun for 10 mins
Restored ACB to normal position*
Unclamped optic
Unlocked ISI
Laid witness plates and 1" witness optic (2 on floor, 2 on QUAD sus)
Removed all tools/guns/lights, etc.
Took TFs of ISI and QUAD for health checks
* When we looked at the ACB earthquake stops after replacing it and noticed that one was very high in the hole. After bantering and worrying about it for an hour, we discovered this alog which says that this is actually how it was tuned to begin with. Jim checked and doesn't see unhealthy vertical TFs, so we're leaving it again.
model restarts logged for Thu 18/Dec/2014
2014_12_18 11:30 h1fw1
unexpected restart. Conlog frequently changing channels report attached.
Blow down dewpoint -26C
Pulling First Contact from ETM-X Replace door on BSC9 BSC10 on roughing pump today. Plan to start turbo pumping on Monday BSC9 on roughing pump after door is on. Plan to start turbo pumping on Monday Electrical cabling work on PEM and OpLevs in the LVEA
Since we turned on cleanrooms in each end station the temperatures have drifted several degrees - ie. out of control. In addition our outdoor temperatures have warmed significantly.
Our electric heat in the outbuildings can be turned on in 15kw stages - which is also roughly the heat output of one large cleanroom.
Last night I decided to turn off the heaters in both buildings to help restore the temperatures to the setpoints of 68F and 65F for EY and EX respectively. Once we turn off the cleanrooms we will consider turning the heat back on. We should attempt to coordinate this so please notify Bubba or John prior to shutting off cleanrooms.
Age related failure of Pirani channels reading the same value -> MKS 937B will be substituted from this point onward via attrition
I left a measurement running overnight -- this will sweep the 9MHz sideband frequency by 20kHz or so and inject a 1kHz oscillation into IMC_F.
To turn off the measurement, select MOD DISABLE on the IFR source in the highbay, and turn off EXC A on the IMC Common Mode Servo screen.
I was trying to figure out how to run the MC alignment offset calibration this afternoon, but ran into some difficulties with new features of the guardian / IMC ASC system. I wasn't able to turn off the ASC loops without the IMC alignment drifting. This wasn't an issue previously, though that was back in February.
Unfortunately, after tinkering with some of the ASC switches etc., the IMC alignment seems to have got into a bad state where it locks, and then drifts in alignment, and then unlocks after about a minute. I put the guardian mode back to exec, and requested locked, but each time the IMC locked the alignment drifted until lock was lost.
To avoid a possible runaway drift overnight, I've put the guardian requesting down.
I came back late to the lab and found the same problem. In order to take some measurements I set the IMC WFS gain to zero. The IMC was stable after that.
J. Kissel, P. Fulda, K. Izumi, K. Venkateswara While trying to get MICH locked again for seismic diagnoses of goodness, Kiwamu found that the H1 SUS ITMY's highest vertical (bounce) mode at 9.7 [Hz] had been rung up. It's the end of the day and no one wants to stick around long enough to really diagnose why it rung up, or attempt to damp it. Our best guess is that the mode got rung up while the SEI team was measuring HEPI tilt-decoupling coefficients (see attached 12 hour trends). Paul and Mackenzie might keep trying, but will most likely just wait until tomorrow for the mode to ring down naturally.
J. Kissel Stefan needed measurements of the HLTS M3 stage for global angular controls (see LHO aLOG 15727), and after taking the first set I found / re-remembered that Betsy and Evan only half finished the import of LLO's damping loop design for the HLTS (see LHO aLOG 15329, and subsequent comments). As such, I've installed the complete set of filters and gains LLO HLTS damping in both H1 SUS PR3 and SR3. I attach a screen shot of how both SR3 and PR3 damping filters are configured (2014-12-18_H1SUS?R3_DAMP.png). M3 to M3 transfer functions with these new damping loops on (shown in the measurement vs. model comparison, allhltss_2014-12-18_Phase3b_H1HLTSs_M3_Don_ALL_ZOOMED_TFs.pdf) is what Stefan and Elli used for the design of the PR3 WFS / Oplev control. Such that design sticks, I've - Foton File - Removed all old filters - Committed new filter file to userapps repo - Safe.snap / EPICs configuration - Turned on the gain-only filters (in FM7 of every DOF), and set all of the EPICs GAINs to -1, as is the case for other suspension types (instead of having the overall gain of the loop in the EPICs GAIN field, as is done at LLO -- see LHO aLOG 15364 for documentation). - Turned off some M3 DRIVEALIGN elements that have been accidentally left ON - Captured a new safe.snap - Committed new safe.snap to the userapps repo. A model of the LLO filters now exists, and lives in the following design script: /ligo/svncommon/SusSVN/sus/trunk/HLTS/Common/FilterDesign/Scripts/design_damping_HLTS_20141218_LLO.m stored .mat file of filters: /ligo/svncommon/SusSVN/sus/trunk/HLTS/Common/FilterDesign/MatFiles/dampingfilters_HLTS_2014-12-18.mat model: /ligo/svncommon/SusSVN/sus/trunk/HLTS/Common/FilterDesign/MatFiles/dampingfilters_HLTS_2014-12-18_model.mat I've attached the model figures of merit, including the loop design, global control TFs, sensor noise, actuator noise, residual seismic noise, and a total assessment of the performance (though I was lazy and didn't add the impulse response that I'd added for the BSFM, QUAD, and HSTS; Next time). Again, I don't both making a comparison with the previous filters because they weren't at all designed with any thought put into them and did not meet any kinda of desirable noise performance, have desirable global control transfer function response, nor did they have a low-Q / low-ring-down-time. The transfer function templates live here: PR3/SAGM3/Data/2014-12-18_2331_H1SUSPR3_M3_WhiteNoise_L_0p01to50Hz.xml PR3/SAGM3/Data/2014-12-18_2331_H1SUSPR3_M3_WhiteNoise_P_0p01to50Hz.xml PR3/SAGM3/Data/2014-12-18_2331_H1SUSPR3_M3_WhiteNoise_Y_0p01to50Hz.xml SR3/SAGM3/Data/2014-12-18_2328_H1SUSSR3_M3_WhiteNoise_L_0p01to50Hz.xml SR3/SAGM3/Data/2014-12-18_2328_H1SUSSR3_M3_WhiteNoise_P_0p01to50Hz.xml SR3/SAGM3/Data/2014-12-18_2328_H1SUSSR3_M3_WhiteNoise_Y_0p01to50Hz.xml I've committed new versions of /ligo/svncommon/SusSVN/sus/trunk/HLTS/Common/MatlabTools/ plotHLTS_dtttfs_M3.m plotallhlts_tfs_M3.m to the SusSVN because I've updated them to include the ability to compare against a damped model and I've added the two new measurements.
Fabrice Krishna Hugh.
Krishna was suspecting that RX tilting on ITMY and the BS was impacting the HEPI Z Sensor correction results. Sure enough, when checked it was most coupled on the BS Z to RX and next on ITMY HEPI Z to RX. The other couplings, that is, HEPI Z to RY, and for ITMY both HEPI Z to RX & RY, where less by about a factor of 10.
The Measurement
HEPI Z is driven with a 0.001 to .1 band pass excitation (see attachment 1) looking for coherence with ISI Stage1 T240 X & Y.
The HEPI is in normal configuration, Lvl1 position loops but with sensor correction off.
The ISI Stage1 all dofs are put into high blend (T750) and its sensor correction is also off.
Once a baseline of the existing HEPI Z to ISI Stage1 T240 to RX & RY coupling is established as seen by the T240 Y & X, the HEPI is then Tilted in RX & RY with a smaller magnitude but similar bandpass to see the actual tilt of the ISI Stage1 when HEPI is tilted. The Decoupling factor is computed by the ratio of the former to the latter: RXz/RXrx. This correction goes into the IPS Align matrix.
Results
See attachment 2 for ITMY. The left three plots are the TF data for inline tilt on ITMY, this is the Y direction caused by RX; the three right plots are for the crossline tilt RY showing on X. The first step is shown in blue: the area below 0.1 to 0.01hz with good coherence is our tilt coupling. Notice on the right side, there is poor coherence and the TF magnitude is 10x smaller than the tilt in the Ydirection seen on the left side.
The green traces are the direct tilt measurement HEPI RX(RY) to ISI RX(RY). Picking a few magnitude points from the blue & green traces in the area of interest and averaging the ratios gives the decoupling factor blue/green= 0.23/46(e.g.) == -0.0049 with the sign coming from the phase which are ~180 out of phase.
The brown trace (only on the left side) shows the reduction with the decoupling factor in the matrix (see last attachment) when the first measurement is repeated. (I failed to save the coherence for this but it was reduced just above 0.8 from the near 1 at the start (blue.) This indicates there may be more improvement to be made but it will be time consuming and may not be worth it. The improvement though is clear, about a factor of 10.
Time constraints (commissioners) prevented a brown results curve measurement for the Z to RY tilting but I have the data to calculate the ratio. We expect the improvement to be minimal as the coupling is already low.
I've attached similar data for the Beamsplitter HEPI. The RX and RY correction values were based on the following measurement:
the transfer function between Z drive to X/Y
Correction value = ------------------------------------------------------------------------
the transfer function between RX/RY drive to X/Y
For the beamsplitter, we measured
RX correction = - 0.0172
RY correction = + 0.0038
The plot shows the transfer function between Z drive to X/Y before and after the tilt decoupling.
Secretary notes from BSC9 today:
We will pull the FC sheet ~9:30 am tomorrow and hopefully get the door back on by lunch.
Note, there were apparently no witness plate or witness optics placed on the floor of BSC9 when it was closed last time, so we did not pick them up today.
Also, I forgot to mention that when we inspected the ETMx-HR, we saw some mottling and haze across the surface but we did NOT see the "ring" feature that the FC left on the ETMy-HR.
The Ops Overview screen that shows the graphic representation of the IFO (OPS_OVERVIEW_CUSTOM.adl) had been previously unable to report individual suspension stage watchdog trips. According to the models, the discreet watchdog stages are "ANDED" into an EPICS channel called $(IFO):SUS-$(LOC)_DACKILL_TRIG_STATE which was the only conditional channel included for the Visibility Calculation in MEDM. This channel will never show it's alarm state unless all upstream watchdogs have been tripped therefore making said "trips" invisible in this overview, which has become a popular one with operators and others as well (imo). Discreet watchdog channels have been added and tested for BS and all Quad suspensions. This overview screen can now be relied on for accurate reporting on the status of any suspension watchdog trips.
TMSs and everything down the output arm has been added to his list, also.
All suspensions have been covered at this point. Please let me know if anyone experiences false reporting of status of suspensions in this view.
Dan, Fil, Thomas
We made a quick modification to the ASC-AS_C transimpedance board today, so that the HAM6 fast shutter threshold can be set for 1W of light into the chamber. The modification was a swap of R23, from 1.24k ohm to 422 ohm. This changes the gain on the SUM_OUT channel on the back of the chassis, that's used for the fast shutter logic.
ASC-AS_C gets 2.5% of the light into HAM6, so we'd like to set the threshold at 25mW. The input to the shutter controller rails at 2V. The QPD transimpedance is 1000 ohms, the quantum efficiency is probably about 80%, and the new resistor changes the final gain stage to 422/4.99k = 0.0845. So, the correct shutter threshold is 0.025*1000*0.8*0.0845 = 1.7 volts.
This modification only affects the signal path to the shutter controller; it doesn't change the signal path that is acquired by the ASC front end. So the ASC-AS_C sum that you see on the MEDM screen hasn't changed. (The input to the HAM6 shutter controller is recorded by the channel H1:SYS-MOTION_C_SHUTTER_G_TRIGGER_VOLTS.)
Something seems odd here. The QPD amp single ended sum output (D1001974) is designed to accommodate the full design dynamic range of the QPD (10mA per quadrant)by use of the R3 = 1.24k and to produce 10V at the sum output during this full scale optical input. The shutter controller (D1102312) photodiode input is a unity gain receiver, although for some bizarre reason, this design only operates on +5V for all the opamps. The correct way to fix this dynamic range problem should have been by lowering R13 from 10k to 2k thus preserving best SNR on the QPD sum output. Also, I see no mention of serial numbers here. Hopefully the eTraveler's are being updated as this is the only way to track such changes at the board and chassis level.
Evan, Alexa
Following the preparation described in alog 15524, we made a ringdown measurement of both the x- and y-arm. For each arm, we locked the IR beam and ran the wfs to ensure maximum build up. We then turned the wfs off, and switched the input polarity of the MC common mode board to unlock the MC quickly (based on LLO's alog 11727 the MC has about a 15usec ringdown time). We used the relfected signal at the AS port to capture the ringdown. We repeated this measurement 10 times to have ample data for our uncertainities. We also measured the "off-resonance" ringdown, by unlocking the arm and misaligning the respective ETM. All the data can be found in /ligo/home/alexan.staley/Public/Ringdown/EX(Y)data (these folders are then split into locked and unlocked times). From this data we calculated the total loss:
X arm: 14310(100) ppm
Y arm: 15000(100) ppm
Based on the galaxy ITMY transmissivity (1.42%) this amounts to 800ppm of loss in the y-arm. Meanwhile, for the x-arm, the ITMX transmissivity is 1.39 % corresponding to a 410ppm loss in the arm. We are in the process of calculating the transmissivity of the ITMs based on our ringdown fit. Our code can be found in /ligo/home/alexan.staley/Public/Ringdown/proccess.py. The y-arm losses seems consitent with our scan measurements; however the x arm does not. These numbers are very sensitive to the transmissivity we use; so before we make an conclusion with this we should inprove our confidence in the transmissivity values.
I’ve attached the code, the data, and the plots in a zip file.
Also attached are a few representative plots with the arms locked and unlocked.
Also, Dave wants me to note that the inferred loss of 410 ppm in the X arm is probably wrong; we’ve just pulled the ITMX transmissivity from the galaxy website instead of extracting it from our data. This is in progress.
The time constant of the ringdown is half of the cavity storage time, and the cavity storage time is related to the arm reflectivities by an equation in Isogai (sec 4.3):
We've assumed that we know RE = 1 − 5×10−6.
Here are the values for the ITM transmissivities, as inferred from the ringdown data.
In summary, to within experimental error there is no anomalous loss in the X arm. In the Y arm, the anomalous loss is 1330(370) ppm.
An updated version of the code is attached, along with a document giving the expression for TITM in terms of the measured quantities.
Here I've assumed RETM = 1, as was done in the paper by Isogai et al.
[Edit: Alexa has pointed out that we need to use m1 = RITM(P0+P1), rather than the original Isogai formula m1 = P0+P1, since we are using a PD in reflection. I've updated the table and the attachments accordingly. The ITM transmissivities change slightly and the extra losses go up a bit, but the conclusions remain the same.]
| X arm | Y arm | |
|---|---|---|
| m1 | 201(5) mV | 153(5) mV |
| m2 | 70(13) mV | 467(30) mV |
| m3 | 203(16) mV | 114(12) mV |
| m4 | 1.863(13) ms | 1.778(12) ms |
| ITM transmission, TITM | 1.419(35) % | 1.366(36) % |
| Total loss, L | 14 310(100) ppm | 14 990(100) ppm |
| L − TITM | 120(360) ppm | 1330(370) ppm |
For posterity, the old, incorrect values for the ITM transmissions were 1.425(35) % for X and 1.37(4) % for Y. The incorrect values for the extra losses were 60(360) ppm for X and 1290(410) ppm for Y.
Check the assumption on ETM transmission? Our measurement is 3.6 ppm with a tolerance of 0.2 ppm for both LHO ETMs. https://dcc.ligo.org/LIGO-E1300313
