J. Kissel

More details to come after I'm able to measure H1SUSOPO again, but as a result of LLO converting to the standard SUS basis (LLO aLOG 38272). and remeasuring their OPOS TFs (LLO aLOG 38308), I've made a comparison between LLO** and LHO's data again and thinks look far more consistent. I've also updated the dynamical model after the (yet to be documented) work Alvaro and I have done during the LVC meeting. In summary, we added several more elements to the stiffness matrix that explain the cross-coupling visible in a lot of the degrees of freedom.

(**Note, the confusion Stuart mentions regarding scale factors was that he didn't remove the special calibration conversion that accounted for the modified HAM-A driver, and the bad units in PRY lever arm basis change when processing the data with 
/ligo/svncommon/SusSVN/sus/trunk/OPOS/Common/MatlabTools/plotOPOS_dtttfs_M1.m. I've fixed and commited the script removing the special LLO case, and now both observatories are calibrated with the same scale factor. I've also re-processed and committed the LLO data.)

Check out the new results attached. The notable differences are in the DOFs that I've not been able to close damping loops: T and Y. T appears to somehow have a sign flip from LLO and expected. Remember we're now using exactly the same basis change matrices. The only difference in the digital system is the magnet compensation signs in the COILOUTF banks, which we believe are correctly compensating the as-built configurations. But, this is to be investigated further. For Y, it looks like the phase at high frequency is asymptoting to a different value. No idea what's going on there.

However, because the results from other DOFs are so similar, I copied over the damping loop design from LLO aLOG 38309, and tried things out. L, V, R, and P are just as successful as LLO. Nice!

Now to still figure out what's going on with T and Y...

I've started the investigation by taking (loops open) T and Y TFs with the L V P and R loops closed, hoping that it might clean things up a bit. The Qs look quite different from the 2018-03-16 measurements, but I ran out of time to investigate further. More tomorrow...

Dan:

late entry from yesterday's maintenance. Dan upgraded the firmware on the two controller cards for E18-1 (written to by h1fw1). Unlike the E18-0 upgrade, this time everything worked as advertised and both CDS writer and the LDAS readers continues to function during the staggered upgrade.

I have restarted the Beckhoff SDF system for c1plc[2,3] following recent changes to these systems. New channels were accepted and monitored. Note that the DAQ has not been restarted for the new channels.

Took several steps backwards today, although it did start off promising.  I re-aligned the output of the front end
laser and got ~90 W output power with a nicer beam.  Spent time optimising the alignment into the pre-modecleaner.
The mode matching was still pretty poor.

    Then the bad news, the diode currents on the PSL Computer were not those on the datasheet.  After setting the
diode currents and temperatures to the datasheet values, the output of the amplifier was ~84 W.  However the
output beam did not appear as good.  The mode matching into the pre-modecleaner was less than 50%.  The beam
propagation was re-measured.



Ed / Peter

All fours fibers have been welded and annealed.  We ended up with a PUM-to-ETM differential pitch of ~3mRad.  We'll attempt to reduce this with a further round of annealing tomorrow.  

16:30 Hugh unlocking HAM6

17:00 Chandra to LVEA

17:00 Travis, Angus, Stephen, Jason to EX

17:45 TVo to LVEA

18:00 Peter to PSL enclosure

18:00 Ed to LVEA

19:45 Fil to CER

20:30 Welding crew to EX

20:30 Sheila and crew headed to HAM6 to find a beam

21:00 Chandra to MY

Kyle, Chandra

We replaced ion pump #6 gate valve and will ship out IP6 for rebuild, which means corner station volume will operate one pump short for a while. The new valve will allow us to install the pump later without venting. In the mean time the valve will get a 16.5" topper with pump port (yet to be located and installed).

Hugh unlocked the HAM6 ISI this morning so I could take some quick transfer functions. Similar to what Arnaud found at LLO's HAM6 after the VOPO install (https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=37394), there are some extra features around the plant resonance. Last I heard, VOPO damping still wasn't functional, so I haven't checked if engaging those affects the ISI tfs, but I think we can say the ISI is probably okay. 

M&M finished wrapping the entire bake enclosure with Al foil and taping the seams. Bottom air temp has reached a new high of 95C (20C less than top air temp). This morning they swapped CP4's GN2 regen heater with CP3's - if we can resurrect that system we may have a chance to bring the entire enclosure up to uniform temperature. I raised the set point of bake enclosure to 130C (from 115C). 

Turbo pump back end measures 55C with 35C cooling water.

Last week the SQZ crew needed to adjust the pitch on ZM1 with the adjustment screw and in doing so, maxed out the adjustment and caused some rubbing. Yesterday I went in and rebalanced the optic holder on its wires to recenter the adjustment screw. I had to back out and then recenter the OSEMs to do this.

I got Terry's help to get a beam onto ZM1 and then checked that, without any damping or offsets, ZM1 was pointing through the apertures with the adjustment screw still relatively in the center of its range. I then double checked the stops were all backed off and buttoned up.

TFs look better in some ways, but still not entirely matching the other tip tilts. Yaw in particular was showing a large second feature that Jeff says is cross coupling from P or L. Now, the feature is much smaller, but still there. The resonant frequencies still seem to be a bit lower than other tip tilts, but again better than before.

Attached the TFs for both undamped (first 3 attached) and damped (last 3).

Thomas Vo, Jenne Driggers, Sheila Dwyer, Daniel Brown, Alexi Ciobanu, Georgia Mansell, Terry McCrae

Today we had a chance to lock the IMC.  

• There were some settings in the MC suspensions that were incorrectly saved in the SDF snap files.  We don't know why these were updated.  Jeff K went through the MC sus, IMC ASC, and LSC SDFs and compared them to the files at the end of O2 to make sure we understood the changes there. We also talked with Dave Barker about developing some kind of tool that lets us look at what changes have been made to SDF files. 
• We reduced the gain by 4dB to avoid the very small gain margin that we had with our usual IMC UGF of around 45kHz.  We think that this small gain margin could be due gain peaking in to the FSS loop, which Peter K had warned us was not remeasured since the 70W amplifier and possible alignment changes in the ref cav path (41156). 
• We are using Jenne's cleaned up guardian code, (41169), which needed a little bit of debugging but seems to be working.  We have used a few of the ALIGN_IFO states, but not actually locked any cavities. 

After the IMC was locking reliably, we briefly looked at PRX.  We were confused for a while because the BS oplev damping was on and driving the suspension an awful lot.  After this was fixed Alexi roughly aligned PRX, and we changed to single bounce.  Using the alignment settings from 40463, we put excitations on SR3 pitch and yaw and can see the beam on the SRM camera some of the time.  We went to HAM6 briefly to look for the beam but didn't find it.  A more careful job of alignment will need to be done tomorrow or the next time we get a chance. 

This morning Corey, Niko and I went to EX and installed most of the remaining PCAL baffle pieces. We looked over the panels, top-gunned them, then I went inside and Corey and Niko handed the pieces to me from the door.  After putting the pieces on, I tried to get a couple of picture of the install and any particulate. First attached image is a view of the installed panels from approximately the the aperture of the arm cavity baffle. 

The barrel baffle pieces were installed a couple weeks ago, and the lower panel has been accumulating particulate, second image. I was pretty easily able to wipe away the fuzzies with a dry wipe, but the barrel panel immediately started accumulating again (third image is the lower panel piece after wiping). Before I left, I did not notice any increased particulate on the front baffle pieces we installed today.  Travis noted before we closed ETMY (the first time?) that the panels on that PCAL had also accumulated some particulate, so it seems we will have to consider adding a wipe down step for the baffles to chamber close out.

Stephen A., Chandra R.

This morning Stephen helped/instructed me on assembly of the first LHO chevron baffle. Baffle SN 001 was installed in nipple housing SN 001. We iterated several times on bending the louvers to securely set them in place and ended with an N2 "top gun" blow off before bolting the two baffle halves together and fastening to the nipple housing. The eight bolts that secure the baffle to the housing still need to be torqued. We placed the two 16.5" Cu gaskets on knife edges and wrapped with Al foil for temporary storage in VPW until we can install on IP11 at EY later this week. Stephen will post pictures later.

Refer to LLO aLOG for more detail on steps of installation. https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=38375

On Friday Terry and I adjusted the crystal position in the OPO to get phase matching and co-resonance at the same temperature. The take away messages are that the crystal translation stage is working and if we correct for mode matching the OPO threshold is between 7.4-8mW, and our phases matching temperature setting in air is just below 34C, both of these are consistent with our expectations.

Details:
We followed the procedure on page 215 of P1300006.  The main idea is to use the crystal temperature at which red and green co-resonante as a reference for crystal position, since both the position of the cavity axis along the wedge and the crystal temperature set the co-resonance.  There are a few caveats to the way we did this:

• The green power in the cavity was different by about 10% between some of these locks, so this is equivalent to about a 10% uncertainty on our measurement of nonlinear gain (if we had kept the green circulating power constant).
• It was difficult to set the co-resonance precisely because of the large noise on the cavity with the ISI locked and the purge air on. We were able to set the crystal position to within about 40 clicks on the translation stage driver.  We found that about 140 clicks are needed to compensate for the dispersion from a temperature change of 0.3C, so all of our temperature settings should be considered accurate to within about 0.1C as a reference for crystal position.
• We measure nonlinear gain by injecting a seed beam, scanning the seed phase, and measuring the de-amplification and amplification of the seed.  (x=(sqrt(max./min)-1)./(1+sqrt(max./min)); gain=1./(1-x).^2;)  In this case we were measuring small changes in the minimum seed power, and not with much accuracy.  This is why in addition to plotting the nonlinear gain, I've also plotted the maximum seed measured on the diode (uncalibrated).  This looks much more like the sinc function we are expecting. 

These caveats can explain why this measurement has large scatter.  We did this measurement with about 6mW of green injected into the OPO, and we saw our best nonlinear gain between 15-20 for this input power.  We can do a better measurement of the OPO threshold by changing the input power at a single crystal position, but this data gives us an estimate of the threshold as between 10 and 11 mW without correcting for our mode mismatch, and between 7.4-8mW correcting for the 74% mode matching from alog 40594. 

The LLO OPO was expected to have a threshold of 45mW with an input coupler that is 87.5% reflective for 532nm, while our input coupler has a reflectivity of 98%.  The threshold power is proportional to the green cavity decay rate, so our expected threshold for this OPO is 7mW (45mW*(1-sqrt(0.875)/(1-sqrt(0.98)). 

Terry and I left the crystal at the position where we see co-resonance for 33.75C, because we think this is about at the peak of the phase matching curve.  This procedure will have to be repeated once HAM6 is pumped down.

Evan G., Jeff K.

We moved a compensation zero out of the ESD output filter bank for each quadrant that had generated an uncompensated 5.2 kHz pole in the DARM loop (see LHO aLOG 33927). This resulted in an effective delay of ~20 usec. There is adequate roll off already from a low pass filter in the ESD driver, so moving this out of the DARM loop will be minimally impactful. Instead, the compensation zero will be a compensation pole in the CAL-CS path and doesn't result in an additional 5.2 kHz zero being added to the Foton filter.

We leave the filter in place and turned on, but the design string is now simply zpk([], [], 1, "n")

The new filter is installed in CS_DARM_ANALOG_ETMY_L3, FM5: zpk([], [3245.33075], 1, "n") (this comes from the mean of the summing node poles, see 27619)

Removing this from the DARM path means that we need to include these as an uncompensated poles in the DARM model and reduce the unknown actuation delay by 20 usec. This will bring the unknown actuation delay down to ~40 usec.

SudarshanK, RickS

To study the downconversion of Pcal excitation we used a DB9 breakout at the back of the Pcal chassis and routed the excitation channel through H1:CAL-PCALX_WS_PD for now. This will be returned to its original configuration once the investigation is complete.

A new line at 86 Hz has appeared in the DARM channels after the vent.

After running BruCo, I've seen that that frequency was coherent with some PCAL channels: https://ldas-jobs.ligo-wa.caltech.edu/~pep.covas/bruco/1181560000/

I attach two different plots showing the differences between before/after the vent for the DARM channels and for  three different PCALX channels . The "before" data is from 07/05/2017 09:00 UTC, and the "after" data is from 15/06/2017 09:00 UTC.

Evan G., Joe B., Jeff K.

Joe B. pointed out that there is an uncompensated ~5.215 kHz pole in the ESD output filter bank because our filter design zpk([3229.1150], [], -1, "n") results in Foton providing a pole to compensate the zero at high frequency. So the actual installed filter is zpk([3229.115],[5215.189175235227],0.9999999999999999,"n").

The ~3.229 kHz zero compensates for a pole in the analog electronics. Unfortunately, the ~5.215 kHz pole is uncompensated. Attached is a Matlab figure showing the effects from 1 Hz to 10 kHz. The band of most interest to us is <200 Hz since above 200 Hz the actuation is sufficiently rolled off that it does not contribute to the response of the interferometer.

Below 200 Hz, there is very small residual magnitude error. Phase, however, is incorrect by ~1.1 degrees at 100 Hz. The equivalent delay is ~30 usec. This could explain part of the unknown actuation delay, which--for LHO--is 61 usec.