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ID Date Author Type Category Subject
14251   Sat Oct 13 20:11:10 2018 yukiUpdateComputer Scripts / Programsloss measurements
 Quote: the script "armloss_AS_calc.py", "ETM_YAW_L_DEMOD_I_OUTPUT" was little noisy even when the arm was locked. The reflected beam power when locked was higher than when misaligned. It seemed strange for me at first. Johannes suggested that it was caused by over-coupling cavity. It is possible when r_{ETMY}>>r1_{ITMY}.

Some changes were made in the script for getting the signals of beam power:

• The script sees "C1:ASS-X(Y)ARM_ETM_PIT/YAW_L_DEMOD_I_OUTPUT" and stops running until the signals become small, however some offset could be on the signal. So I changed it into waiting until (DEMOD - OFFSET) becomes small. (Yesterday I wrote ETM_YAW_L_DEMOD_I_OUTPUT was about 15 and was little noisy. I was wrong. That was just a offset value.)
• I added a code which stops running the script when the power of transmitted IR beam is low. You can set this threshold. The nominal value of "C1:LSC-TRX(Y)_OUT16" is 1.2 (1.0), so the threshold is set 0.8 now.

In the yesterday measurement the beam power of ASDC is higher when locked than when misaligned and I wrote it maybe caused by over-coupled cavity. Then I did a calculation as following to explain this:

• assume power transmissivity of ITM and ETM are 1.4e-2 and 1.4e-5.
• assume loss-less mirror, you can calculate amplitude reflectivity of ITM and ETM.
• consider a cavity which consists two mirrors and is loss-less, then $\frac{E_{r}}{E_{in}} = \frac{-r_1+r_2e^{i\phi}}{1-r_1r_2e^{i\phi}}$ holds. r1 and r2 are amplitude reflectivity of ITM and ETM, and E is electric filed.
• Then you can calculate the power of reflected beam when resonated and when anti-resonated. The fraction of these value is $\frac{P_{RESONANT}}{P_{ANTI-RESO}} = 0.996$, which is smaller than 1.
• I found this calculation was wrong! Above calculatation only holds when cavity is aligned, not when misaligned. 99.04% of incident beam power reflects when locked, and (100-1.4)% reflects when misaligned. The proportion is P(locked)/P(misaligned)=1.004, higher than 1.

14253   Sun Oct 14 16:55:15 2018 not gautamUpdateCDSpianosa upgrade

DASWG is not what we want to use for config; we should use the K. Thorne LLO instructions, like I did for ROSSA.

 Quote: pianosa has been upgraded to SL7. I've made a controls user account, added it to sudoers, did the network config, and mounted /cvs/cds using /etc/fstab. Other capabilities are being slowly added, but it may be a while before this workstation has all the kinks ironed out. For now, I'm going to follow the instructions on this wiki to try and get the usual LSC stuff working.
14254   Mon Oct 15 10:32:13 2018 yukiUpdateComputer Scripts / Programsloss measurements

I used these values for measuring armloss:

• Transmissivitity of ITM = 1.384e-2 * (1 +/- 1e-2)
• Transmissivitity of ETM = 13.7e-6 * (1 +/- 5e-2)
• Mode-Matching efficiency of XARM = 0.912 * (1 +/- 2e-2)
• Mode-Matching efficiency of YARM = 0.867 * (1 +/- 2e-2)
• modulation depth m1 (11MHz) = 0.179 * (1 +/- 2e-2)
• modulation depth m2 = 0.226 * (1 +/- 2e-2),

then the uncertainties reported by the individual measurements are on the order of 6 ppm (~6.2 for the XARM, ~6.3 for the YARM). This accounts for fluctuations of the data read from the scope and uncertainties in mode-matching and modulation depths in the EOM. I made histograms for the 20 datapoints taken for each arm: the standard deviation of the spread is over 6ppm. We end up with something like:

XARM: 123 +/- 50 ppm
YARM: 152+/- 50 ppm

This result has about 40% of uncertaintities in XARM and 33% in YARM (so big... ).

In the previous measurement, the fluctuation of each power was 0.1% and the fluctuation of P(Locked)/P(misaligned) was also 0.1%. Then the uncertainty was small. On the other hand in my measurement, the fluctuation of power is about 2% and the fluctuation of P(Locked)/P(misaligned) is 2%. That's why the uncertainty became big.

We want to measure tiny value of loss (~100ppm). So the fluctuation of P(Locked)/P(misaligned) must be smaller than 1.6%.

(Edit on 10/23)
I think the error is dominated by systematic error in scope. The data of beam power had only 3 degits. If P(Locked) and P(misaligned) have 2% error, then
$\frac{P_L}{P_M}\frac{1}{1+T_{\mathrm{ITM}}} = 0.99(3)$.
You have to check the configuration of scope.

Attachment 1: XARM_20181015_1500.pdf
Attachment 2: YARM_20181015_1500.pdf
 Quote: but there's one weirdness: It get's the channel offset wrong. However this doesn't matter in our measurement because we're subtracting the dark level, which sees the same (wrong) offset.

When you do this measurement with oscilloscope, take care two things:

1. set y-range of scope as to every signal fits in display: otherwise the data sent from scope would be saturated.
2. set y-position of scope to the center and don't change it; otherwise some offset would be on the data.
14256   Mon Oct 15 13:59:42 2018 SteveUpdateVACdrypump replaced

Steve & Bob,

Bob removed the head cover from the housing to inspect the condition of the the tip seal. The tip seal was fine but the viton cover seal had a bad hump. This misaligned the tip seal and it did not allow it to rotate.

It was repositioned an carefully tithened. It worked. It's starting current transiant measured 28 A and operational mode 3.5 A

This load is normal with an old pump. See the brand new DIP7 drypump as spare was 25 A at start and  3.1 A in operational mode. It is amazing how much punishment a slow blow ceramic 10A  fuse can take [ 0215010.HXP ]

In the future one should measure the current pick up [ transient <100ms ] after the the seal change with Fluke 330 Series Current Clamp

It was swapped in and the foreline pressure dropped to 24 mTorr after 4 hours. It is very good. TP3 rotational drive current  0.15 A at 50K rpm   24C

 Quote: Gautam and Steve, Our TP3 drypump seal is at 360 mT [0.25A load on small turbo]  after one year.  We tried to swap in old spare drypump with new tip  seal. It was blowing it's fuse, so we could not do it. Noisy aux drypump turned on and opened to TP3 foreline [ two drypumps are in  the foreline now ]  The pressure is 48 mT and 0.17A load on small turbo.

Attachment 1: drypump_swap.png
14258   Tue Oct 16 00:44:29 2018 yukiUpdateComputer Scripts / Programsloss measurements

The scripts for measuring armloss are in the directory "/opt/rtcds/caltech/c1/scripts/lossmap_scripts/armloss_scope".

• armloss_derefl_asdcpd_scope.py: gets data and makes ascii file.
• armloss_AS_calc.py: calculates armloss from selected a set of files.
• armloss_calc_histogram.py: calculates armloss from selected files and makes histogram.
14259   Wed Oct 17 09:31:24 2018 SteveUpdatePSLmain laser off

The main laser went off when PSL doors were opened-closed. It was turned back on and the PSL is locked.

Attachment 1: Inno2wFlipped_off.png
14261   Thu Oct 18 00:27:37 2018 KojiUpdateSUSSUS PD Whitening board inspection

[Gautam, Koji]

As a part of the preparation for the replacement of c1susaux with Acromag, I made inspection of the coil-osem transfer function measurements for the vertex SUSs.

The TFs showed typical f^-2 with the whitening on except for ITMY UL (Attachment 1). Gautam told me that this is a known issue for ~5 years.
We made a thorough inspection/replacement of the components and identified the mechanism of the problem.
It turned out that the inputs to MAX333s are as listed below.

 Whitening ON Whitening OFF UL ~12V ~8.6V LL 0V 15V UR 0V 15V LR 0V 15V SD 0V 15V

The switching voltage for UL is obviously incorrect. We thought this comes from the broken BIO board and thus swapped the corresponding board. But the issue remained. There are 4 BIO boards in total on c1sus, so maybe we have replaced a wrong board?

Initially, we thought that the BIO can't drive the pull-up resistor of 5KOhm from 15V to 0V (=3mA of current). So I have replaced the pull-up resistor to be 30KOhm. But this did not help. These 30Ks are left on the board.

Attachment 1: 43.png
14262   Mon Oct 22 15:19:05 2018 SteveUpdateVACMaglev controller serviced

Gautam & Steve,

Our controller is back with Osaka maintenace completed. We swapped it in this morning.

 Quote: TP-1 Osaka maglev controller  [  model TCO10M,  ser V3F04J07 ]  needs maintenance. Alarm led  on indicating  that we need Lv2 service. The turbo and the controller are in good working order. ***************************** Hi Steve, Our maintenance level 2 service price is \$...... It consists of a complete disassembly of the controller for internal cleaning of all ICB’s, replacement of all main board capacitors, replacement of all internal cooling units, ROM battery replacement, re-assembly, and mandatory final testing to make sure it meets our factory specifications. Turnaround time is approximately 3 weeks.   RMA 5686 has been assigned to Caltech’s returning TC010M controller. Attached please find our RMA forms. Complete and return them to us via email, along with your PO, prior to shipping the cont Best regards, Pedro Gutierrez Osaka Vacuum USA, Inc. 510-770-0100 x 109 ************************************************* our TP-1 TG390MCAB is 9 years old. What is the life expectancy of this turbo?                         The Osaka maglev turbopumps are designed with a 100,000 hours(or ~ 10 operating years) life span but as you know most of our end-users are                         running their Osaka maglev turbopumps in excess of 10+, 15+ years continuously.     The 100,000 hours design value is based upon the AL material being rotated at                         the given speed.   But the design fudge factor have somehow elongated the practical life span.   We should have the cost of new maglev & controller in next year budget. I  put the quote into the wiki.

Attachment 1: our_controller_is_back.png
14263   Thu Oct 25 16:17:14 2018 SteveUpdatesafetysafety training

Chub Osthelder received 40m specific basic safety traning today.

14264   Wed Oct 31 17:54:25 2018 gautamUpdateVACCC1 hornet power connection restored

Steve reported to me that the CC1 Hornet gauge was not reporting the IFO pressure after some cable tracing at EX. I found that the power to the unit had been accidentally disconnected. I re-connected the power and manually turned on the HV on the CC gauge (perhaps this can be automated in the new vacuum paradigm). IFO pressure of 8e-6 torr is being reported now.

Attachment 1: cc1_Hornet.png
14266   Fri Nov 2 10:24:20 2018 SteveUpdatePEMroof cleaning

Physical plan is cleaning our roof and gutters today.

14267   Fri Nov 2 12:07:16 2018 ranaUpdateCDSNDScope

https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=44971

Let's install Jamie's new Data Viewer

14268   Fri Nov 2 16:42:31 2018 aaronUpdateComputer Scripts / Programsarm loss measuremenents

I'm continuing the arm loss measurements Yuki was making. I'm first familiarizing myself with the procedures for the measurement Johannes describes.

I'm not very familiar with the medm screens, so I'm just kind of poking around and checking with Gautam. I do the following:

1. Turned Xarm ASS dither on, then off.
2. Turned X and Y ALS on, then off shortly after
1. Realizing I needed some guidance, I found this page on lock acquisition on the wiki
2. Gautam showed me how to align/lock the IFO so I could take some notes, and we locked the Y arm, misaligned X.
3. I put the PD back in the AS beam path to get the ASDC signal, and approximately centered the beam. This PD is on channel 1 of the scope, which is at 192.168.113.24.
4. I centered the beam onto the MC2 PD that Yuki had installed. This PD is on channel 2 of the scope.
1. Both scope channels are set to 1V scale (I also had tried 500mV, and it didn't seem to make a difference) and 10s time axis spacing (maximum integration time, since we're looking for a DC effect. Is this what we want?)
2. The impedance for both channels is 1MOhm.
5. I ran the script to start the loss measurement on the Y arm.
1. python2 armloss_dcrefl_asdcpd_scope.py 192.168.113.24 1 2 5 YARM
2. I'm reading ~15 (au?) for the MC channel and ~5% of that out the AS, which seems to make sense to me and looked to be about what Yuki the ratios when I checked the log files. However, I'm a bit confused by the normalization, because the maximum output of the MC PD is 10V, and indeed the scope's display is reading under 10V.

I've left the script running.

14269   Fri Nov 2 19:25:16 2018 gautamUpdateComputer Scripts / Programsloss measurements

Some facts which should be considered when doing this measurement and the associated uncertainty:

1. When Johannes did the measurement, there was no light from the AS port diverted to the OMC. This represents ~70% loss in the absolute amount of power available for this measurement. I estimate ~1W*Tprm * Ritm * Tbs * Rbs * Tsrm * OMCsplit ~ 300uW which should still be plenty, but the real parameter of interest is the difference in reflected power between locked/no cavity situations, and how that compares to the RMS of the scope readout. For comparison, the POX DC light level is expected to be ~20uW, assuming a 600ppm AR coating on the ITMs.
2. Even though the reflection from the arm not being measured may look like it's completely misaligned looking at the AS camera, the PDA520 which is used at the AS port has a large active area and so one must check on the oscilloscope that the other arm is truly misaligned and not hitting the photodiode to avoid interference effects artifically bloating the uncertainty.
3. The PDA255 monitoring the MC transmission has a tiny active area. I'm not sure the beam has been centered on it anytime recently. If the beam is not well centered on that PD, and you normalize the measurements by "MC Transmission", you're likely to end up with larger error.
 Quote: This result has about 40% of uncertaintities in XARM and 33% in YARM (so big... ).
14270   Mon Nov 5 13:52:18 2018 aaronUpdateComputer Scripts / Programsarm loss measuremenents

After running this script Friday night, i noticed Saturday that the data hadn't saved. Scrolling up inthe terminal, I couldn't see where I'd run the script, so I thought I'd forgotten to run it as I was making last minute changes to the scope settings Friday before leaving.

Monday it turns out I hadn't forgotten to run the script, but the script itself was getting hung up as it waited for ASS to settle, due to the offset on the ETM PIT or YAW setpoints. The script was waiting until both pitch and yaw settled to below 0.7, but yaw was reading ~15; I think this is normal, and it looks like Yuki had solved this problem by waiting for the DEMOD-OFFSET to become small, rather than just the DEMOD signal to be small. Since this is a solved problem, I think I might be using an old script, but I'm pretty sure I'm running the one in Johannes' folder that Yuki is referencing for example here. The scripts in /yutaro_scripts/ have this DEMOD-OFFSET functionality commented out, and anyway those scripts seem to do the 2D loss maps rather than 1D loss measurements.

In the meantime I blocked the beams and ran the script in DARK mode. The script is saving data in /armloss/data/run_20181105/, and runs with no exceptions thrown.

However, when I try to dither align the YARM, I get an error that "this is not a degree of freedom that has an ASS". I'm alsogetting some exceptions from MEDM about unavailable channels. It must have been something about donatella not initializing, because it's working on pianosa. I turned on YARM ADS from pianosa. Monitoring from dataviewer, I see that LSC-TRY_OUT has some spikes to 0.5, but it's mostly staying near 0. I tried returning to the previous frozen outputs, and also stepping around ETMY-[PIT/YAW] from the IFO_ALIGN screen, but didn't see much change in the behavior of LSC-TRY. I missed the other controls Gautam was using to lock before, and I've also made myself unclear on whether ASS is acting only on angular dof, or also on length.

I unblocked the beams after the DARK run was done.

14273   Tue Nov 6 10:03:02 2018 SteveUpdateElectronicsContec board found

The Contec test board with Dsub37Fs was on the top shelf of E7

Attachment 1: DSC01836.JPG
14274   Tue Nov 6 10:19:26 2018 aaronUpdateComputer Scripts / Programsarm loss measuremenents

I'm checking out the data this morning, running armloss_AS_calc.py using the parameters Yuki used here.

I made the following changes to scripts (measurement script and calculator script)

• Included the 'hour' of the run in the armloss_dcrefl_* script. This way, we can run more than once a day without overwriting data.
• Changed the calculator script to loop over all iterations of locked/misaligned states, and calculate the loss for adjacent measurements.
• That is, the measurement script will make a measurement with the arm locked, then with it misaligned, and repeat that N times
• The calculator now finds the loss for the nth iteration using *_n_locked and *_n_misaligned, and finds N separate loss measurements
• The dark signal is also computed N times, though all of the dark measurements are made before running the arm scripts, so they could be all integrated together.
• All of these are saved in the same directory that the data was grabbed from.

I repeated the 'dark' measurements, because I need 20 files to run the script and the measurements before had the window on the scope set larger than the integration time in the script, so it was padded with bad values that were influencing the calculation.

On running the script again, I'm getting negative values for the loss. I removed the beamstops from the PDs, and re-centered the beams on the PDs to repeat the YARM measurements.

14275   Tue Nov 6 15:23:48 2018 gautamUpdateIOOIMC problematic

The IMC has been misbehaving for the last 5 hours. Why? I turned the WFS servos off. afaik, aaron was the last person to work on the IFO, so i'm not taking any further debugging steps so as to not disturb his setup.

Attachment 1: MCwonky.png
14276   Tue Nov 6 15:32:24 2018 SteveUpdatePSLMC_Transmitted

I tried to plot a long trend MC Transmitted today. I could not get farther than 2017 Aug 4

 Quote: The mode cleaner was misaligned probably due to the earthquake (the drop in the MC transmitted value slightly after utc 7:38:52 as seen in the second plot). The plots show PMC transmitted and MC sum signals from 10th june 07:10:08 UTC over a duration of 17 hrs. The PMC was realigned at about 4-4:15 pm today by rana. This can be seen in the first plot.

Attachment 1: MC_Trans.png
14277   Tue Nov 6 19:02:35 2018 aaronUpdateIOOIMC problematic

That was likely me. I had recentered the beam on the PD I'm using for the armloss measurements, and I probably moved the wrong steering mirror. The transmission from MC2 is sent to a steering mirror that directs it to the MC2 transmission QPD; the transmission from this steering mirror I direct to the armloss MC QPD (the second is what I was trying to adjust).

Note: The MC2 trans QPD goes out to a cable that is labelled MC2 op lev. This confusion should be fixed.

I realigned the MC and recentered the beam on the QPD. Indeed the beam on MC2 QPD was up and left, and the lock was lost pretty quickly, possibly because the beam wasn't centered. Lock was unstable for a while, and I rebooted C1PSL once during this process because the slow machine was unresponsive.

When tweaking the alignment near MC2, take care not to bump the table, as this also chang es the MC2 alignment.

Once the MC was stably locked, I was able to maximize MC transmission at ~15,400 counts. I then centered the spot on the MC2 trans QPD, and transmission dropped to ~14800 counts. After tweaking the alignment again, it was recovered to ~15,000 counts. Gautam then engaged the WFS servo and the beam was centered on MC2 trans QPD, transmission level dropped to ~14,900.

Attachment 1: 181106_MCTRANS.jpg
14279   Tue Nov 6 23:19:06 2018 gautamUpdateVACc1vac1 FAIL lights on (briefly)

Jon and I stuck a extender card into the eurocrate at 1X8 earlier today (~5pm PT), to see if the box was getting +24V DC from the Sorensen or not. Upon sticking the card in, the FAIL LEDs on all the VME cards came on. We immediately removed the extender card. Without any intervention from us, after ~1 minute, the FAIL LEDs went off again. Judging by the main volume pressure (Attachment #1) and the Vacuum MEDM screen (Attachment #2), this did not create any issues and the c1vac1 computer is still responsive.

But Steve can perhaps run a check in the AM to confirm that this activity didn't break anything.

Is there a reason why extender cards shouldn't be stuck into eurocrates?

Attachment 1: Screenshot_from_2018-11-06_23-18-23.png
Attachment 2: Screenshot_from_2018-11-06_23-19-26.png
14280   Wed Nov 7 05:16:16 2018 yukiUpdateComputer Scripts / Programsarm loss measuremenents

Please check your data file and compare with those Johannes made last year. I think the power in your data file may have only three-disits and flactuate about 2%, which brings huge error. (see elog: 40m/14254)

 Quote: On running the script again, I'm getting negative values for the loss.
14281   Wed Nov 7 08:32:32 2018 SteveUpdateVACc1vac1 FAIL lights on (briefly)...checked

The vacuum and MC are OK

 Quote: Jon and I stuck a extender card into the eurocrate at 1X8 earlier today (~5pm PT), to see if the box was getting +24V DC from the Sorensen or not. Upon sticking the card in, the FAIL LEDs on all the VME cards came on. We immediately removed the extender card. Without any intervention from us, after ~1 minute, the FAIL LEDs went off again. Judging by the main volume pressure (Attachment #1) and the Vacuum MEDM screen (Attachment #2), this did not create any issues and the c1vac1 computer is still responsive. But Steve can perhaps run a check in the AM to confirm that this activity didn't break anything. Is there a reason why extender cards shouldn't be stuck into eurocrates?

Attachment 1: Vac_MC_OK.png
14283   Wed Nov 7 19:20:53 2018 gautamUpdateComputersPaola Battery Error

The VEA vertex laptop, paola, has a flashing orange indicator which I take to mean some kind of battery issue. When the laptop is disconnected from its AC power adaptor, it immediately shuts down. So this machine is kind of useless for its intended purpose of being a portable computer we can work at optical tables with. The actual battery diagnostics (using upower) don't report any errors.

14284   Wed Nov 7 19:42:01 2018 gautamUpdateGeneralIFO checkup and DRMI locking prep

Earlier today, I rebooted a few unresponsive VME crates (susaux, auxey).

The IMC has been unhappy for a couple of days - the glitches in the MC suspensions are more frequent. I reset the dark offsets, minimized MCREFL by hand, and then re-centered the beam on the MC2 Trans QPD. In this config, the IMC has been relatively stable today, although judging by the control room StripTool WFS control signal traces, the suspension glitches are still happening. Since we have to fix the attenuator issue anyways soon, we can do a touch-up on IMC WFS.

I removed the DC PD used for loss measurements. I found that the AS beam path was disturbed - there is a need to change the alignment, this just makes it more work to get back to IFO locking as I have to check alignment onto the AS55 and AS110 PDs.

Single arm locking worked with minimal effort - although the X arm dither alignment doesn't do the intended job of maximizing the transmission. Needs a checkup.

PRMI locking (carrier resonant) was also pretty easy. Stability of the lock is good, locks hold for ~20 minutes at a time and only broke because I was mucking around. However, when the carrier is resonant, I notice a smeared scatter pattern on the ITMX camera that I don't remember from before. I wonder if the FF idea can be tested in the simpler PRMI config.

After recovering these two simpler IFO configurations, I improved the cavity alignment by hand and with the ASS servos that work. Then I re-centered all the Oplev beams onto their respective QPDs and saved the alignment offsets. I briefly attemped DRMI locking, but had little success, I'm going to try a little later in the evening, so I'm leaving the IFO with the DRMI flashing about, LSC mode off.

14285   Wed Nov 7 23:07:11 2018 gautamUpdateLSCDRMI locking recovered

I had some success today. I hope that the tweaks I made will allow working with the DRMI during the day as well, though it looks like the main limiting factor in lock duty cycle is angular stability of the PRC.

• Since there has been some change in the light levels / in vacuum optical paths, I decided to be a bit more systematic.
• Initial guess of locking gains / demod phases was what I had last year.
• Then I misaligned SRM, and locked PRMI, for the sideband resonant in the PRC (but still no arm cavities, and using 1f Refl error signals).
• Measured loop TFs, adjusted gains, re-enabled boosts.
• Brought the SRM back into the picture. Decided to trigger SRCL loop on AS110I rather than the existing POP22I (because why should 2f1 signal buildup carry information about SRCL?). New settings saved to the configure script. Reduced MICH gain to account for the SRC cavity gain.
• Re-measured loop TFs, re-adjusted gains. More analysis about the state of the loops tomorrow, but all loops have UGF ~100-120 Hz.
• Ran some sensing lines - need to check my sensing matrix making script, and once I get the matrix elements, I can correct the error signal demod phasing as necessary.

[Attachment #1]: Repeatable and reliable DRMI locks tonight, stability is mainly limited by angular glitches - I'm not sure yet if these are due to a suspect Oplev servo on the PRM, or if they're because of the tip-tilt PR2/PR3/SR2/SR3.

[Attachment #2]: A pass at measuring the TF from SRCL error point to MICH error point via control noise re-injection. I was trying to measure down to 40 Hz, but lost the lock, and am calling it for the night.

[Attachment #3]: Coherence between PRM oplev error point and beam spot motion on POP QPD.

Note that the MICH actuation is not necessarily optimally de-coupled by actuating on the PRM and SRM yet (i.e. the latter two elements of the LSC output matrix are not precisely tuned yet).

What is the correct way to make feedforward filters for this application? Swept-sine transfer function measurement? Or drive broadband noise at the SRCL error point and then do time-domain Wiener filter construction using SRCL error as the witness and MICH error as the target? Or some other technique? Does this even count as "feedforward" since the sensor is not truly "outside" the loop?

Attachment 1: Screenshot_from_2018-11-07_23-05-58.png
Attachment 2: SRCL2MICH_crosscpl.pdf
Attachment 3: PRCangularCoh_rot.pdf
14286   Fri Nov 9 15:00:56 2018 gautamUpdateIOONo IFO beam as TT1 UL hijacked for REFL55 check

This problem resurfaced. I'm doing the debugging.

6:30pm - "Solved" using the same procedure of stepping through the whitening gains with a small (10 DAC cts pk) signal applied. Simply stepping through the gains with input grounded doesn't seem to do the trick.

Attachment 1: REFL55_wht_chk.png
14288   Sat Nov 10 17:32:33 2018 gautamUpdateLSCNulling MICH->PRCL and MICH->SRCL

With the DRMI locked, I drove a line in MICH using the sensing matrix infrastructure. Then I looked at the error points of MICH, PRCL and SRCL. Initially, the sensing line oscillator output matrix for MICH was set to drive only the BS. Subsequently, I changed the --> PRM and --> SRM matrix elements until the line height in the PRCL and SRCL error signals was minimized (i.e. the change to PRCL and SRCL due to the BS moving, which is a geometric effect, is cancelled by applying the opposite actuation to the PRM/SRM respectively. Then I transferred these to the LSC output matrix (old numbers in brackets).

MICH--> PRM = -0.335 (-0.2655)

MICH--> SRM = -0.35 (+0.25)

I then measured the loop TFs - all 3 loops had UGFs around 100 Hz, coinciding with the peaks of the phase bubbles. I also ran some sensing lines and did a sensing matrix measurement, Attachment #1 - looks similar to what I have obtained in the past, although the relative angles between the DoFs makes no sense to me. I guess the AS55 demod phase can be tuned up a bit.

The demodulation was done offline - I mixed the time series of the actuator and sensor signals with a "local oscillator" cosine wave - but instead of using the entire 5 minute time series and low-passing the mixer output, I divvied up the data into 5 second chunks, windowed with a Tukey window, and have plotted the mean value of the resulting mixer output.

Unrelated to this work: I re-aligned the PMC on the PSL table, mostly in Pitch.

Attachment 1: sensMat_2018-11-10.pdf
14289   Sat Nov 10 17:40:00 2018 aaronUpdateIOOIMC problematic

Gautam was doing some DRMI locking, so I replaced the photodiode at the AS port to begin loss measurements again.

I increased the resolution on the scope by selecting Average (512) mode. I was a bit confused by this, since Yuki was correct that I had only 4 digits recorded over ethernet, which made me think this was an i/o setting. However the sample acquisition setting was the only thing I could find on the tektronix scope or in its manual about improving vertical resolution. This didn't change the saved file, but I found the more extensive programming manual for the scope, which confirms that using average mode does increase the resolution... from 9 to 14 bits! I'm not even getting that many.

There's another setting for DATa:WIDth, that is the number of bytes per data point transferred from the scope.

I tried using the *.25 scope instead, no better results. Changing the vertical resolution directly doesn't change this either. I've also tried changing most of the ethernet settings. I don't think it's something on the scripts side, because I'm using the same scripts that apparently generated the most recent of Johannes' and Yuki's files; I did look through for eg tds3014b.py, and didn't see the resolution explicitly set. Indeed, I get 7 bits of resolution as that function specifies, but most of them aren't filled by the scope. This makes me think the problem is on the scope settings.

14290   Mon Nov 12 13:53:20 2018 ranaUpdateIOOloss measurement: oscope vs CDS DAQ

sstop using the ssscope, and just put the ssssignal into the DAQ with sssssome whitening. You'll get 16 bitsśšß.

 Quote: I increased the resolution on the scope by selecting Average (512) mode. I was a bit confused by this, since Yuki was correct that I had only 4 digits recorded over ethernet, which made me think this was an i/o setting. However the sample acquisition setting was the only thing I could find on the tektronix scope or in its manual about improving vertical resolution. This didn't change the saved file, but I found the more extensive programming manual for the scope, which confirms that using average mode does increase the resolution... from 9 to 14 bits! I'm not even getting that many.

14291   Tue Nov 13 16:15:01 2018 SteveUpdateVACrga scan pd81 at day 119

Attachment 1: pd81-d119.png
Attachment 2: pd81-560Hz-d119.png
14292   Tue Nov 13 18:09:24 2018 gautamUpdateLSCInvestigation of SRCL-->MICH coupling

Summary:

I've been looking into the cross-coupling from the SRCL loop control point to the Michelson error point.

[Attachment #1] - Swept sine measurement of transfer function from SRCL_OUT_DQ to MICH_IN1_DQ. Details below.

[Attachment #2] - Attempt to measure time variation of coupling from SRCL control point to MICH error point. Details below.

[Attachment #3] - Histogram of the data in Attachment #2.

[Attachment #4] - Spectrogram of the duration in which data in #2 and #3 were collected, to investigate the occurrance of fast glitches.

Hypothesis: (so that people can correct me where I'm wrong - 40m tests are on DRMI so "MICH" in this discussion would be "DARM" when considering the sites)

• SRM motion creates noise in MICH.
• The SRM motion may be naively decomposed into two contributions -
• Category #1: "sensing noise induced" motion, which comes about because of the SRCL control loop moving the SRM due to shot noise (or any other sensing noise) of the SRCL PDH photodiode, and
• Category #2: all other SRM motion.
• We'd like to cancel the former contribution from DARM.
• The idea is to measure the transfer function from SRCL control point to the MICH error point. Knowing this, we can design a filter so that the SRCL control signal is filtered and summed in at the MICH error point to null the SRCL coupling to MICH.
• Caveats/questions:
• Introducing this extra loop actually increases the coupling of the "all other" category of SRM motion to MICH. But the hypothesis is that the MICH noise at low frequencies, which is where this increased coupling is expected to matter, will be dominated by seismic/other noise contributions, and so we are not actually degrading the MICH sensitivity.
• Knowing the nosie-budget for MICH and SRCL, can we AC couple the feedforward loop such that we are only doing stuff at frequencies where Category #1 is the dominant SRCL noise?

Measurement details and next steps:

Attachment #1

• This measurement was done using DTT swept sine.
• Plotted TF is from SRCL_OUT to MICH_IN, so the SRCL loop shape shouldn't matter.
• I expect the pendulum TF of the SRM to describe this shape - I've overlaid a 1/f^2 shape, it's not quite a fit, and I think the phase profile is due to a delay, but I didn't fit this.
• I had to average at each datapoint for ~10 seconds to get coherence >0.9.
• The whole measurement takes a few minutes.

Attachments #2 and #3

• With the DRMI locked, I drove a sine wave at 83.13 Hz at the SRCL error point using awggui.
• I ramped up the amplitude till I could see this line with an SNR of ~10 in the MICH error signal.
• Then I downloaded ~10mins of data, demodulated it digitally, and low-passed the mixer output.
• I had to use a pretty low corner frequency (0.1 Hz, second order butterworth) on the LPF, as otherwise, the data was too noisy.
• Even so, the observed variation seems too large - can the coupling really change by x100?
• The scatter is huge - part of the problem is that there are numerous glitches while the DRMI is locked.
• As discussed at the meeting today, I'll try another approach of doing multiple swept-sines and using Craig's TFplotter utility to see what scatter that yields.

Attachments #2

• Spectrogram generated with 1 second time strides, for the duration in which the 83 Hz line was driven.
• There are a couple of large fast glitches visible.
Attachment 1: TF_sweptSineMeas.pdf
Attachment 2: digitalDemod.pdf
Attachment 3: digitalDemod_hist.pdf
Attachment 4: DRMI_LSCspectrogram.pdf
14293   Tue Nov 13 21:53:19 2018 gautamUpdateCDSRFM errors

This problem resurfaced, which I noticed when I couldn't get the single arm locks going.

The fix was NOT restarting the c1rfm model, which just brought the misery of all vertex FEs crashing and the usual dance to get everything back.

Restarting the sender models (i.e. c1scx and c1scy) seems to have done the trick though.

Attachment 1: RFMerrors.png
14294   Wed Nov 14 14:35:38 2018 SteveUpdateALARM emergency calling list for 40m Lab

It is posted at the 40m wiki with Gautam' help. Printed copies posted around doors also.

14295   Wed Nov 14 18:58:35 2018 aaronUpdateDAQNew DAC for the OMC

I began moving the AA and AI chassis over to 1X1/1X2 as outlined in the elog.

The chassis were mostly filled with empty cables. There was one cable attached to the output of a QPD interface board, but there was nothing attached to the input so it was clearly not in use and I disconnected it.

I also attach a picture of some of the SMA connectors I had to rotate to accommodate the chassis in their new locations.

Update:

The chassis are installed, and the anti-imaging chassis can be seen second from the top; the anti-aliasing chassis can be seen 7th from the top.

I need to breakout the SCSI on the back of the AA chassis, because ADC breakout board only has a DB36 adapter available; the other cables are occupied by the signals from the WFS dewhitening outputs.

Attachment 1: 6D079592-1350-4099-864B-1F61539A623F.jpeg
Attachment 2: 5868D030-0B97-43A1-BF70-B6A7F4569DFA.jpeg
14297   Thu Nov 15 10:21:07 2018 aaronUpdateIOOIMC problematic

I ran a BNC from the PD on the AS table along the cable rack to a free ADC channel on the LSC whitening board. I lay the BNC on top of the other cables in the rack, so as not to disturb anything. I also was careful not to touch the other cables on the LSC whitening board when I plugged in my BNC. The PD now reads out to... a mystery channel. The mystery channel goes then to c1lsc ADC0 channels 9-16 (since the BNC goes to input 8, it should be #16). To find the channel, I opened the c1lsc model and found that adc0 channel 15 (0-indexed in the model) goes to a terminator.

Rather than mess with the LSC model, Gautam freed up C1:ALS-BEATY_FINE_I, and I'm reading out the AS signal there.

I misaligned the x-arm then re-installed the AS PO PD, using the scope to center the beam then connecting it to the BNC to (first the mystery channel, then BEATY). I turned off all the lights.

I went to misalign the x-arms, but the some of the control channels are white boxed. The only working screen is on pianosa.

The noise on the AS signal is much larger than that on the MC trans signal, and the DC difference for misaligned vs locked states is much less than the RMS (spectrum attached); the coherence between MC trans and AS is low. However, after estimating that for ~30ppm the locked vs misaligned states should only be ~0.3-0.4% different, and double checking that we are well above ADC and dark noise (blocked the beam, took another spectrum) and not saturating the PD, these observations started to make more sense.

To make the measurement in cds, I also made the following changes to a copy opf Johannes' assess_armloss_refl.py that I placed in /opt/rtcds/caltech/c1/scripts/lossmap_scripts/armloss_cds/   :

• function now takes as argument the number of averages, averaging time, channel of the AS PD, and YARM|XARM|DARK.
• made the data save to my directory, in /users/aaron/40m/data/armloss/

I started taking a measurement, but quickly realized that the mode cleaner has been locked to a higher order mode for about an hour, so I spend some time moving the MC. It would repeatedly lock on the 00 mode, but the alignment must be bad because the transmission fluctuates between 300 and 1400, and the lock only lasts about 5 minutes.

Attachment 1: 181115_chansDown.png
Attachment 2: PD_noise.png
14298   Fri Nov 16 00:47:43 2018 gautamUpdateLSCMore DRMI characterization

Summary:

• More DRMI characterization was done.
• I was working on trying to improve the stability of the DRMI locks as this is necessary for any serious characterization.
• Today I revived the PRC angular feedforward - this was a gamechanger, the DRMI locks were much more stable. It's probably worth spending some time improving the POP LSC/ASC sensing optics/electronics looking towards the full IFO locking.
• Quantitatively, the angular fluctuations as witnessed by the POP QPD is lowered by ~2x with the FF on compared to off [Attachment #1, references are with FF off, live traces are with FF on].
• The first DRMI lock I got is already running 15 mins, looking stable.
• Update: Out of the ~1 hour i've tried DRMI locking tonight, >50 mins locked!
• I think the filters can be retrained and this performance improved, something to work on while we are vented.
• Ran sensing lines, measured loop TFs, analysis tomorrow, but I think the phasing of the 1f PDs is now okay.
• MICH in AS55 Q, demod phase = -92deg, +6dB wht gain.
• PRCL in REFL11 I, demod phase = +18 deg, +18dB wht gain.
• SRCL in REFL55 I, demod phase = -175 deg, +18dB wht gain.
• Also repeated the line in SRCL-->witness in MICH test.
• At least 10 minutes of data available, but I'm still collecting since the lock is holding.
• This time I drove the line at ~124 Hz with awggui, since this is more a regime where we are sensing noise dominated.

Prep for this work:

• Reboots of c1psl, c1iool0, c1susaux.
• Removed AS port PD loss measurement PD.
• Initial alignment procedure as usual: single arms --> PRMI locked on carrier --> DRMI

I was trying to get some pics of the optics as a zeroth-level reference for the pre-vent loss with the single arms locked, but since our SL7 upgrade, the sensoray won't work anymore . I'll try fixing this during the daytime.

Attachment 1: PRCff.pdf
Attachment 2: DRMI_withPRCff.png
14299   Fri Nov 16 10:26:12 2018 SteveUpdateVAC single viton O-rings

The 40m vacuum envelope has one large single O-ring on the OOC west side. All other doors have double O-ring with annuloses.

There are 3  spacers to protect o-ring. They should not be removed!

The Cryo-pump static seal to VC1 also viton. All gate valves and right angle valve plates have single viton o-ring seal.

Small single viton o-rings on all optical quality viewports.

Helium will permiate through these fast. Leak checking time is limited to 5-10 minutes.

All other seals are copper gaskits. We have 2 manual right angle with METAL-dynamic seal [ VATRING ] as  VV1 & RV1

Attachment 1: Single-O-ring.png
14300   Fri Nov 16 10:53:07 2018 aaronUpdateIOOIMC problematic

Back to loss measurements.

I replaced the PD I've been using for the AS beam.

I misaligned the x arm.

I tried to lock the y arm, but PRC was locked so I could was unable. Gautam reminded me where the config scripts are.

The armloss measurement script needed two additional modifications:

• It was setting the initial offset of the PIT and YAW demod signals to 0, but due to the clipping on the heater we are operating at an offset. I commented out these lines.
• When the script ran UNFREEZE_DITHER, it was running it using medmrun. The scope script hadn't been using this, and it seemed that when it ran UNFREEZE_DITHER in this way the YARM_ASS servo was passing only '0'. I don't really know why this was, but when I removed the call to medmrun it worked.

I ran successfully the loss measurement script for the x and y arms. I'm getting losses of ~100ppm from the first estimates.

I made the following changes to the lossmap script:

• make the averaging time an input to the script, so we can exceed 2 second averages
• remove anything about getting data from the scope, replace it with the correct analogues to save the averages for POX/POY refl, MC trans, op lev P/Y, and ASDC signal.
• record the GPS time in the file with the cds averages (this way I can grab the full data)
• Added a step in the lossmap script to misalign the optic, so we can continue getting data for the 'misaligned' state, both for the centered and not-centered measurements (that is, for every position on the lossmap).

When the optic aligns itself not at the ideal position, I'm noticing that it often locks on a 01. When the cavity is then misaligned and restored, it can no longer obtain lock. To fix this, I've moved my 'save' commands to just before the loop begins. This means the script may take longer to run, but as long as the cavity is initially locked and well aligned, this should make it more robust against wandering off and never reacquiring lock.

I left the lossmap script running for the x-arm. Next would be to run it for the y arm, but I see that after stepping to a few positions the lock is again lost. It's still trying to run, but if you want to stop it no data already taken will be lost. To stop it, go to the remaining terminal open on rossa and ctrl+c

the analysis needs:

• Windowing
• Filter, don't average
• detrend to get rid of the linear drifts in lock that we see.
• Is this the right thing?
Attachment 1: Screenshot_from_2018-11-16_19-22-34.png
14302   Sat Nov 17 18:59:01 2018 aaronUpdateIOOIMC problematic

I made additional measurements on the x and y arms, at 5 offset positions for each arm (along with 6 measurements at the "zeroed" position).

14303   Sun Nov 18 00:59:33 2018 gautamUpdateGeneralVent prep

I've begun prepping the IFO for the vent, and completed most of the IFO related items on the checklist. The power into the MC has been cut, but the low-power autolocker has not been checked. I will finish up tomorrow and post the go ahead. PSL shutter is closed for tonight.

14304   Sun Nov 18 17:09:02 2018 gautamUpdateGeneralVent prep

Vent prep

Following the checklist, I did these:

• Both arms were locked to IR, TRY and TRX maximized using ASS.
• GTRY and GTRX were also maximized.
• ITM/ETM Oplevs centered with TRX/TRY maximized, PRM/SRM/BS Opelvs were centered once the DRMI was locked and aligned.
• Attachment #1 summarizes the above 3 bullets.
• Sensoray was made to work with Donatella (Raspberry Pi video server idea is good but although the sensoray drivers look to have installed correctly, when the Sensoray unit is plugged into the RPi USB port, the red light doesn't come on, so I opted to not spend too much time on it for the moment).
• Photos of all ports in various locked configurations are saved in /users/sensoray/SensorayCaptures/Nov2018Vent
• PSL power into the IMC was cut from 1.07 W (measured after G&H mirror) to 97 mW. I opted to install a new HWP+PBS after the PMC to cut the power, so we don't have to fiddle around so much with the PMC locking settings [Attachment #3, this was the only real candidate location as the IMC wants s-polarized light].
• 2" R=10% BS in the IMC REFL path was replaced with a 2" Y1 HR mirror, so there is no MCREFL till we turn the power back up.
• IMC was locked.
• Low power MC autolocker works [Attachment #2]. The reduction in MCREFL is because of me manually aligning the cavity, WFS servos are disabled in low power mode since there is no light incident on the WFS heads.
• Updated the SUS driftmon values (though I'm not really sure how useful this is).
• PSL shutter will remain closed, but I have not yet installed a manual beam block in the beam path on the PSL table.

@Steve & Chub, we are ready to vent tomorrow (Monday Nov 19).

Attachment 1: VentPrepNov2018.png
Attachment 2: MCautolocker_lowPower.png
Attachment 3: IMG_7163.JPG
14305   Mon Nov 19 14:59:48 2018 ChubUpdateVACVent 81

Vent 80 is nearly complete; the instrument is almost to atmosphere.  All four ion pump gate valves have been disconnected, though the position sensors are still connected,and all annulus valves are open.  The controllers of TP1 and TP3 have been disconnected from AC power. VC1 and VC2 have been disconnected and must remained closed. Currently, the RGA is being vented through the needle valve and the RGA had been shut off at the beginning of the vent preparations.  VM1 and VM3 could not be actuated.  The condition status is still listed as Unidentified because of the disconnected valves.

14306   Mon Nov 19 17:09:00 2018 SteveUpdateVACVent 81

Gautam, Aaron, Chub and Steve,

 Quote: Vent 80 is nearly complete; the instrument is almost to atmosphere.  All four ion pump gate valves have been disconnected, though the position sensors are still connected,and all annulus valves are open.  The controllers of TP1 and TP3 have been disconnected from AC power. VC1 and VC2 have been disconnected and must remained closed. Currently, the RGA is being vented through the needle valve and the RGA had been shut off at the beginning of the vent preparations.  VM1 and VM3 could not be actuated.  The condition status is still listed as Unidentified because of the disconnected valves.

The vent 81 is completed.

4 ion pumps and cryo pump are at ~ 1-4 Torr (estimated as we have no gauges there), all other parts of the vacuum envelope are at atm. P2 & P3 gauges are out of order.

V1 and VM1 are in a locked state. We suspect this is because of some interlock logic.

TP1 and TP3 controllers are turned off.

Valve conditions as  shown: ready to be opened or closed or moved or rewired. To re-iterate: VC1, VC2, and the Ion Pump valves shouldn't be re-connected during the vac upgrade.

Thanks for all of your help.

Attachment 1: beforeVent82.png
Attachment 2: vent81completed.png
14307   Mon Nov 19 22:01:50 2018 gautamUpdateVACLoose nut on valve

As I was turning off the lights in the VEA, I heard a rattling sound from near the PSL enclosure. I followed it to a valve - I couldn't see a label on this valve in my brief effort to find one, but it is on the south-west corner of the IMC table, so maybe VABSSCI or VABSSCO? The power cable is somehow spliced with an attachment that looks to be bringing gas in/out of the valve (See Attachment #1), and the nut on the bottom was loose, the whole power cable + mettal attachment was responsible for the rattling. I finger-tightened the nut and the sound went away.

Attachment 1: IMG_7171.JPG
14310   Tue Nov 20 13:13:01 2018 gautamUpdateVACIMC alignment is okay

I checked the IMC alignment following the vent, for which the manual beam block placed on the PSL table was removed. The alignment is okay, after minor touchup, the MC Trans was ~1200 cts which is roughly what it was pre-vent. I've closed the PSL shutter again.

14311   Tue Nov 20 17:38:13 2018 ranaUpdateUpgradeNew Coffee Machine

Rana, Aaron, Gautam

The old Zojirushi has died. We have received and comissioned our new Technivoorm Mocha Master today. It is good.

14312   Tue Nov 20 20:33:11 2018 aaronUpdateOMCOMC scanning/aligning script

I finished running the cabling for the OMC, which involved running 7x 50ft DB9 cables from the OMC_NORTH rack to the 1X2 rack, laying cables over others on the tray. I tried not to move other cables to the extent I could, and I didn't run the new cables under any old cables. I attach a sketch diagram of where these cables are going, not inclusive of the entire DAC/ADC signal path.

I also had to open up the AA board (D050387, D050374), because it had an IPC connector rather than the DB37 that I needed to connect. The DAC sends signals to a breakout board that is in use (D080302) and had a DB37 output free (though note this carries only 4 DAC channels). I opened up the AA board and it had two IPC 40s connected to an adapter to the final IPC 70 output. I replaced the IPC40 connectors with DB37 breakouts, and made a new slot (I couldn't find a DB37 punch, so this is not great...) on the front panel for one of them, so I can attach it to the breakout board.

I noticed there were many unused wires, so I had to confirm that I had the wiring correct (still haven't confirmed by driving the channels, but will do). There was no DCC for D080302, but I grabbed the diagrams for the whitening boards it was connected to (D020432) and for the AA board I was opening up as well as checked out elog 8814, and I think I got it. I'll confirm this manually and make a diagram if it's not fake news.

Attachment 1: pathwaysketch.pdf
Attachment 2: IMG_0094.JPG
Attachment 3: IMG_0097.JPG
14313   Wed Nov 21 09:59:26 2018 gautamUpdateLSCLSC feedforward block diagram

Attachment #1 is a block diagram depicting the pathway by which the vertex DOF control signals can couple into DARM (adapted from a similar diagram in Gabriele's Virgo note on the subject). I've also indicated some points where noise can couple into either loop. In general, there are sensing noises that couple in at the error point of the loop, and actuation noises that couple in at the control point. In this linear picture, each block represents a (possibly time varying) transfer function. So we can write out the node-to-node transfer functions and evaluate the various couplings.

The motivation is to see if we can first simulate with some realistic noise and time-varying couplings (and then possibly test on the realtime system) the effectiveness of the filter denoted by "FF" in canceling out the shot noise from the auxiliary loop being re-injected into the DARM loop via the DARM sensor. Does this look correct?

Attachment 1: IMG_7173.JPG
ELOG V3.1.3-