Hanford transportation will haul on day shift and swing shift on Friday 12/12, and ERDF will operate a Friday day shift. No weekend work is scheduled.
Kiwamu, Dave O, Elli
Here are better quality images of ETMx. These images were taken with the same method as for the ETMy images in alog 15547. The exposure level was 500000 microseconds (compared to 10000 for ETMy.)
The camera isn't well focused, because we choose to increase the camera apperature to maximum, which limited our ability to focus.
I was trying to understand a strange temperature bump at MIDX VEA and Richard noticed that there had been a very abrupt excursion outside.
This event turned out to be responsible for the VEA bump I observed at MIDX. The outside temperature rose from 42F to 54F in about 45 minutes
Take a look at these two outside temperatures from X and Y recorded yesterday around 8 pm.
The end stations were not affected since we still have chillers operating there.
JimW did this Tilt Decoupling 14 April; those values he came up with have managed to survive and were still in the CPS Align Matrix. Since we've done lots of changes in many places, we thought a check of tilt decoupling was in order. This morning I repeated the measurement and adjusted the numbers around these historic values. I changed both RX & RY decouple numbers at the same time during the tests.
The first attached is the results for driving in the Y direction. The left column is for the in line coupling; that is, pitching response adjusted by the RX-Y component of the ALIGN matriix. The right column shows the cross response--rolling about the Y axis adjusted by the RY-Y Matrix element.
The blue traces are with the original values, -.001/.0005 for RX/RY to Y elements. Green is the change to -.0015/.00075; brown are with the elements at -.0005/.000 for RX/RY.
The red traces are with the final desired values. Looking at the left inline values, the original blue trace with RX-Y at -.001 looks best. For the cross term RY-Y, it looks best at .00075 shown on the green trace--notice the greatly reduced coherence and lowered amplitude in the lower right and upper right plots respectively. When these 'best' values are used for the red results, things don't look quite as good as the green and the blue but may be the best compromise. This really shows the couplings here and the pain given the length of these measurements.
The second attachment shows driving in X. The blue curves show the original values for RX-X & RY-X. These are the best numbers as my bracketing around these makes the coupling higher seen in the green and red curves: The left column has the blue most linear and in the right column you see the lowest coherence and magnitude for the blue as well.
Templates for these measurements are in /ligo/svncommon/SeiSVN/seismic/BSC-ISI/H1/ETMY/Data/Transfer_Functions/Measurements/Tilt_Decouple/
As a preparation for doing some DRMI ASC, I've added a loop that servos SR2 to the AS_C QPD. (see LLO alog 15840)
As Keita centered AS_C after he finished unclipping the output arm (alog 15145), we can servo SR2 to this QPD to avoid clipping on the Faraday. The input and output matrix elements are 1, the output goes to M2, the gain for PIT is 500 and Yaw is 3000. These are both low bandwidth loops for now. The hope is that this will make using WFS to control the SRM more robust, as was seen at LLO. We'll see when we get a chance to lock DRMI.
After several false starts the new auto-centering software is finally ready to go. The attached screen shot shows the new medm screens. The screen to the left is the main servo screen. It shows the DC readouts of the WFSs leading to pitch and yaw matrices which then are fed into the new integrator filter modules (IFM). The screen to the right shows the new trigger logic. The auto centering is engaged automatically, when there is enough light on the WFSs, when the IFMs are in auto mode and when the main enable switch is on. This SUM thresholds are adjusted on the trigger screen. Whenever the SUM trigger is off, the corresponding integrators are bled off. This ensures that they come back to a good state, if they get completely out of alignment. The later is sometimes introduced by a misalignment of the ETM.
The RMS thresholds are used to decide, if the PZT servos have settled. The logical AND of all triggers is sent to the WFS servos as an additional trigger to engaged the alignment servos.
The attached pdf shows a typical transfer function of an auto-centering servo with a ugf of 10 Hz.
Elli, Daniel
We noticed that PZT2 used for centering WFS_B in end X was out of alignment range. We were tapping at different mounts to see if something was flaky. Indeed, we found that the PZT mirror was not very well attached. This is a press-fit mount and had too much slack. We jammed in a piece of plastic material and realigned the path.
The nds2-client software for Linux has been updated on the DAQ test stand to version 0.10.5 (which is listed as the current version on the LSC NDS2 Trac web page).
model restarts logged for Wed 10/Dec/2014
2014_12_10 12:13 h1iscey
2014_12_10 12:16 h1iscex
2014_12_10 12:20 h1iscex
2014_12_10 12:20 h1iscey
2014_12_10 12:24 h1broadcast0
2014_12_10 12:24 h1dc0
2014_12_10 12:24 h1fw0
2014_12_10 12:24 h1fw1
2014_12_10 12:24 h1nds0
2014_12_10 12:24 h1nds1
2014_12_10 16:48 h1iscey
no unexpected restarts. Continuation of code change for end station ISC (with associated DAQ restart). later h1iscey restart to track excitation problem. Conlog frequently changing channels list attached.
Stefan, Paul, Kiwamu,
Tonight, we conitued working on the PRMI carrier lock. It is getting stable again.
(PR3 DC-coupled oplev servo)
Locking the PRMI, we immediately noticed PR3 drifting, which resulted in lock loss in a few minutes after lock is acquired. This is something we already knew (see for example alog 13837). First, we decreased the PSL power to 5 W in order to reduce whatever the thermal effect on PR3. Then we worked on the oplev servo on PR3 to pin it down on a certain angle. Since the PR3 opelv loop had been modified to be AC-coupled (alog 14719 from this past October), we put it back to DC-coupled again. This was done by adding some zero-pole pairs in the existing M2 stage damping loop. The DC couepling filter now resides in FM9. See the attached for the new DC-coupled filter. The blue curve is the original AC-coupled open-loop TF and the red is the new DC-coupled one. Note that the overall gain in the plot is not adjusted. The DC-coupled PR3 oplev gave enough stability that we can then work on some ASC loops.
(ASC loops)
We then closed two ASC loops in order to maintain the PRMI at high build up. Currently we engage the follwoing loops; AS_A_45Q -> MICH and REFL_B_9I -> PRM. Since we have already setup the control filters and suspensions, we simply changed the input matrix without chainging the servo gains. Here are the input matrix elements that we used:
This gave more stable lock which could last more than 30 minutes. Most of the lock loss was due to just us trying to make some changes in situ. Also, we needed to engage the BS top mass length feedback in order to keep it for many minutes because of high seismic.
(BS oplev glitching again)
Even with the ASC loops engaged, the ASDC fluctuated a lot. It could fulctuate from 4000 counts to 40000 counts at low frequencies below 1 Hz. Apparently the low frequency signal was associated with some kind of fast angular motion which was visible in the REFL, POP and AS cameras. We then found that the BS oplev was glitching and therefore giving fast transient into BS. It looked like it was happening mainly in yaw. This needs a close look tomorrow.
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
Dave O, Elli, Kiwamu
We have improved the dynamic range of the scatter pictures we took last night. We did this by:
-Changng analog gain on the camera from 1023 to 100.
-Changing from 8 bit to 12 bit enconding
-Averaging over 100 images rather than just using one.
We now have a much clearer picture of scattering off of ETMy. We took an image of ETMy with IR locked and green misaligned. We then subtracted a background image with both green and IR misaligned. We plotted the images using log10 of the intensity. We have also included the same image plotted with linear intesnity, which can be compared directly to last night's image.
Daniel was seeing problems running excitations to the ISC EY integrators, but at the time was not seeing the same problems at EX. We restarted h1iscey to restart its awgtpman. Problems persist at EY and now EX is seeing intermittent excitations. We'll take a closer look tomorrow. This is not a filtermodule excitation channel, rather an excitation part in the model.
Evan and Alexa working on ringdown measurements Daniel and Dave changing h1iscex and h1iscey models Jim W. and Krishna working on seismic sensor correction 07:25 Jeff and Bubba moving 3IFO storage containers in the LVEA 07:32 Karen and Cris into the LVEA 08:57 Filiberto and Aaron cabling in the LVEA 09:16 Corey and Kiwamu to the squeezer bay 09:16 Filiberto to end Y to look at the illuminator and dust monitors 09:35 Jim W. and Krishna to the CER 09:46 Jim W. and Krishna back 09:56 Karen cleaning at mid Y 10:19 Dave to mid X to label racks 10:48 Karen leaving mid Y 10:54 Dave back 11:55 Bubba, Jeff and Andres done 3IFO work in the LVEA. LVEA is back to full laser hazard. 12:00 Filiberto and Aaron done 12:36 Kyle and Gerardo taking engine hoist from corner station to end Y 13:14 Cyrus to mid X, end X and end Y to work on surveillance cameras 14:20 Kyle and Gerardo done Cyrus done
J. Warner, K. Venkateswara
The LLO sensor correction was implemented at the rest of the test mass chambers, after installing it yesterday at ETMX. Plots are attached.
There is a significant difference in performance between chambers despite the CPS sensors showing about the same level of subtraction (~10). ETMY_Y shows only a factor of 2 improvement at 0.43 Hz, while ITMX shows the full factor of 10 improvement. We are not sure why this is the case yet, but we'll look linto the isolation loops tomorrow.
S. Dwyer, K. Venkateswara
Sheila helped me align ITMX. We then looked at the OPLEV to see if the sensor correction had improved the Pitch and Yaw of the optics. Once again, as we saw in 15498, the Pitch and Yaw remain unchanged, as they are dominated by Ry and Rz respectively as seen by the coherence. This will likely affect the cavity control as well, unless the WFS are on which we will try tomorrow.
Rz could be improved if we could reproduce Arnaud's results. Ry improvement will be harder.
All outdoor and indoor units are on site. Indoor units are all hung and refrigeration lines are being connected. Outdoor units will be set next week after the concrete pad is poured. Partition wall is up and sheet rock in place, taping and paint next week.
K. Venkateswara
After the changes to the way BRS is used at ETMX, detailed in 15497, tilt-subtraction shows significant improvement. Attached files show ASD plots from 40k seconds of data from last night, when winds were barely a few mph at ETMX.
The first plot is in angle units. The blue line shows the ground seismometer output, the green shows the raw BRS output and the red curve shows the new tilt-subtracted super-sensor output. The roll-off at 5 mHz is due to the high-pass filter but most of the other difference is from the new tilt-subtraction. This is also clear in the coherence plot shown below - the coherence between the super-sensor and the T240 is less than the coherence between the T240 and BRS. The BRS ref is shown in cyan.
The tilt-subtracted super-sensor is tilt-free and reliable till ~30 mHz or so. Why is this important? For one thing, it can be used to do sensor-correction to Stage 1 of the BSC-ISI, while keeping tilt-reinjection at a minimum. This has the effect of reducing the microseism, which is a big problem at LLO and will be a problem here as well. This was shown recently in 15498.
Some data from last night when winds were at an incredible ~5 mph! :)
Dan, Kiwamu,
We locked the PRMI on the sidebands to assess the current recyclying gains. The result will be posted later.
We did the initial alignment sequence to get back to a good global interferomter alignment. One thing I have to note is that I had to touch PR3 in yaw by 2 urads in order to recover a high RF power in ALS COMM. It is now back to 3 dBm in the monitor. Also this gave a good spot position on the ALS X camera as it was clipping before I moved PR3. The clipping seems to be fixed now on the camera. I aligned TMSY, ETMY and ITMY using the green light with a hope that they still represent a good IR alignment. After going through all the alignment sequence, the ALS DIFF beatnote came back to a high RF power of about 0 dBm. So I think the global alignment came back to as good as before.
The PRMI was locked very easily by setting LSC_CONFIGS to PRMI_sb_OFFLOADED. Then we aligned the OMs and did OMC scans in order to evaluate the recyclying gains. The data is now under some analysis. After the OMC scan, we attempted to lock the PRMI on the carrier, by simply flipping the sign of the PRCL control sign. We tried different gain settings MICH which uses REFL45Q, but did not get good lock tonight. So, we still don't know the carrier recycling gain.
We locked the PRMI on carrier. The carrier recyclying gain was measured to be 35 at highest. However, since the alignment was not perfect, it probably would go up. To be continued.
After playing with the gain settings, we eventually became able to lock the PRMI on carrier. However the alignment was not stable to keep it locked with high build-up. I think this needs more study to understand what is going on. Anyway, so far, the highest buidl-up in POPAIR_A_LF we had tonight was about 3.5x104 uW. When the simple MICH without power-recycling was locked, POPAIR_A_LF was about 30 uW. Assuming that there is no mode-mismatch and Tp=0.03, we get a recycling gain of 3.5x104 / 30 * Tp = 35.
LSC settings:
Attached are the OMC scan results for a PRMI sideband lock, compared to a scan from a single-bounce beam. The first plot shows the results of three single-bounce scans and three PRMi scans (100 second ramps of PZT2); the second plot has averaged the traces. The PRMI data appears to be shifted upwards compared to the single-bounce data, by about 1V in the PZT2 output. We expect some drift and hysteresis in the PZT, but the single-bounce data was taken immediately after the PRMI lock, and a shift of this size is...surprising.
Using Kiwamu's expression from alog:14532, I calculate the PRC gain of the 45MHz sideband to be about 11.8 or 14, depending on which sideband peak you use. I think this is lower than we expect. The PRMI sideband lock was quite wobbly with a lot of angular motion, we might get a more robust measurement by locking the OMC to a particular mode and maximizing the transmission.
Here is a table of peak heights:
| Sideband Freq. | Single-bounce data | PRMI Data |
| -45 | 0.31 | 3.98 |
| -9 | 0.17 | 2.45 |
| 9 | 0.17 | 0.22 |
| 45 | 0.31 | 4.70 |
With a Schnupp asymmetry of 9.5cm the gain, for example for the upper 45MHz sideband, is (4.7/0.31) * (0.03*0.5*0.5) * (1/sin(2*pi*0.095*5*9100230/c)**2) = 13.9.
Just for a book-keeping purpose:
Two weeks later from this entry, we have measured the recycling of the carrier with the ASC loops fully engaged. We measured it to be 45 (see alog 15793).
