[Sheila, Paul]

After the recent increase in power it was discovered that IO_AB_PD2 (the Thorlabs PDA55 PD in transmission of the PSL periscope lower mirror) was saturating. We went to the PSL to adjust the transimpedance gain to bring the signal in range again, and also to check the power incident on the PD and the periscope to get an updated calibration factor for power into the IMC.

We measured 276uW on IO_AB_PD2 with VEGA power meter (small head for low power, with the filter off). We measured 8.82W at the lower periscope mirror with the VEGA power meter (large head for high power, no filter). We waited maybe 5mins for the reading to stabilize. This gives us a pick off fraction form the main beam to IO_AB_PD2 of 3.13E-5.

With the PDA55 gain set to its lowest setting (quoted as 15kV/A in the spec sheet), we measured 1.38 V on the output. We can use this to calculate the responsivity of the detector as R [A/W] = 1.38 [V] / (1.5E4 [V/A] x 2.78E-4 [W]) = 0.33 [A/W]. Comparing with the frustratingly gridless plot in the datasheet here: http://www.thorlabs.us/thorcat/2000/PDA55-Manual.pdf this doesn't look far wide of the mark.

I've set the values in the H1:PSL-PERISCOPE_A_DC calibration path accordingly, after some minor adjustments were made to account for the 0.01V offset we observed on the PD.

The H1:PSL-PERISCOPE_A_DC_POWERMON channel shown on the IMC overview screen is now reading ~8800mW, as it should do based on the power meter measurement made before the periscope mirror.

The H1:IMC-PWR_IN_OUTPUT channel which is also shown on the IMC overview screen is, I believe, not currently acquired.

In preparation for acceptance review of the ETMX quadruple suspension, I took a set of ASD of the osems in the local and euler basis. ETMX is in chamber, under vacuum and the ISI was in its level 1 isolated state (ST1 = T100mHz blend on X and Y, T750mHz for the other DOF, ST2 = 750mHz blend). Measurement was taken successively with suspension damping on and off.

The main resonnances of main and reaction chains are well damped for all degrees of freedom.

The minor things to notice are :

Damping for the vertical DOF of the reaction chain is not having much effect on the first resonnance (@~ 0.56Hz) (see p9 of 2nd pdf).

The upper left osem of L2 level has its noise floor above the usual sensor noise we see on other osems (see p34 of 3rd pdf).

Otherwise everything else looks good.

The results attached are :

1) Comparison damping off/on for the top mass sensors of the main chain

2) Same for the reaction chain

3) Comparison between different quads (H1 ETMX H1 ETMY L1 ITMY L1 ITMX) of all osem sensors in local and euler basis.

A safe snapshot will need to be taken when possible since I found the normV/R/P filters disengaged, and a gain of 10 in the L2L L1 sensalign matrix. I also corrected the channel list of the plotquadspectra.m since it was requesting two times the L1_WIT_L channels. The modified script was commited to the svn

I had another occurence where a cleared integrator history in the tidal relieve servo to ETMX HPI  tripped everything at the end station.

To try to avoid that in the future I added p0.1:z10 filers on the HPI ISCINF input filters, and an p10:z0.1 anti filter BEFORE the switched integrator. This way any turn on or off should be soft.

We'll see whether it works.

[A. Pele, S. Biscans, J. Warner, H. Radkins, F. Clara, R. McCarthy, K. Kawabe, J. Kissel]

We've been chasing the source of an exactly-0.5 [Hz] oscillation (and subsequent higher-order harmonics) in the H1 ISI ITMX, that was first identified in LHO aLOG 9494. After testing the ISI in many different configurations (See LHO aLOGs 9546, 9951, 9585, and 9605), and ruling out capacitive position sensors -- already been shown to have *other* oscillations and frequency combs because an unrelated problem with beating oscillator sync frequencies, see LLO aLOG 10629 -- we narrowed down the source of the problem to the Y3 channel of the Corner 3 T240 on Stage 1. With a single channel to attack, we launched Filiberto on the problem. He identified and fixed the problem (as indicated in 9607). I attach some visual aides to describe the problem; see H1ISIITMX_CableProblem.pdf, and further details below. I also attach a comparison of the performance using the same metrics as in the original discovery, with the ISI in the same control system configuration, but now with all combs absent. We get an RMS of 70 [nrad] in Pitch, which appears to be "pretty good" for the green team. Nice work, gents!

The path forward (for this chamber): This ISI still does not have sensor correction running, LLO's really-low-frequency blend filters, nor has it had any attention paid to optimizing the rotational DOFs to minimize sensor-noise, tilt-horizontal-coupling. All of these things can improve the stage 1 performance between ~0.1 [Hz] and 1 [Hz]. Further, we can probably add more gain to the QUAD damping loop filters at 0.56 [Hz] (the remaining peak corresponding the first "pitch" mode). There is some resonant gain already present, but I can check if we can add more -- the filters were designed for a Monolithic QUAD, where ITMX is a Wire-Hang QUAD and they have different first pitch mode frequencies. Further, we have done any coil balancing or frequency-dependent alignment decoupling which may also help.

Note that we still have to solve the CPS Oscillator Beat Frequency Combs resulting from other chambers, but that's another problem for another day (Rich Mittleman lands tomorrow, and that's one of his primary tasks).

Details:
-------- 
The Problem (w/ visual aides):
- PG1: A screenshot of the BSC-ISI Wiring Diagram (D0901301-v10, pg 10), showing the big-picture of the T240 signal chain, from the actual sensor inside the pod, inside the ISI, inside the BSC chamber to the cable going from the T240 Interface Chassis to the Anti-Aliasing chassis. The problem was inside the cable-side of the connection at the T240 Interface chassis, on the rack side of the long cable run from the chamber flange to the rack, which I've circled in red.
- PG2: A zoomed in screenshot of the chassis. The busted pin, Pin 2, which carries the positive leg of either the Y / V DOF had been broken inside the backshell of the cable. I've again circled the problem in red. Fil originally identified the flaw by testing the continuity of the cable and found the dead short on that pin. Fil conjectures that the pin failed because, again inside the backshell, the male pin had been over-crimped and/or not seated well, such that repeated normal use of the connector and bending of the cable caused the connection to snap.
- PG3: An example of a male DB25 connector, looking at the side which would be enclosed inside the backshell, and an associated pin. The pin is crimped to the signal cable, and press-fit in the connector hole.
- PG4: An example of a male DB25 connector, looking at the external connection side. I've only pushed the pin half-way in, but one can see how the pin might be mistaken for functional, but still not be fully seated.

Current Configuration of the ISI in this measurement:
- ISI-ITMY and ISI-BS CPS OFF
- HPI-ITMX running Level 1 Isolation Filters, with a position sensor only blend filters on all DOFs.
- ISI-ITMX running Level 1 Isolation Filters, with "T100mHz_N0.44" blends on ST1 XY and "750mHz" on ST1 ZRXRYRX and all of ST2. Note with out the extra 0.5 [Hz] notch that was the temporary temporary solution from a few days ago.
- SUS-ITMX running Level 2.1 damping loops.

The History:
Jim recalled having problems with this exact channel just after the cartridge install in mid-November 2013: though they were able to find a configuration in which their spectra passed acceptance testing (see E1100848), they spent a few days trying to fix a low-gain issue with this same channel (exactly a factor of two). Though we could not find any associated aLOGs, or saved raw data, Jim did managed to find a few saved .pdfs of the problem, one of which I attach here (see ITMX_ASD_after_filter_reload_2013_11_15.pdf). At the time, Jim and Seb were focused on solving the fact that the channel had a factor-of-two lower gain that the other 8 T240 DOFs, and in the rush that was ITMX they didn't notice the minor bump at 0.5 [Hz]. Further, he and Sebastian spent several days on it, because the fact-of-two problem was intermittent, and found that jostling the cable at the flange (not at the rack) was the most effective way to mitigate it. It went further unnoticed until we began *using* the T240s in the ST1 isolation loops. In summary -- this cable problem has been present ever since its install, but due to the usual chaos of a chamber install, plus the holidays, plus the rotating door of seismic commissioners with higher priorities, it was missed. HOWEVER, I really don't put anyone nor any testing procedure at fault; this is a 1 and 1000, perfect storm of problems that we will continue to have for the next few years as we begin to push the aLIGO systems to their designed performance levels.

~ 4:35 - 5:20

Put 'H1 EtherCAT' labels on front of h1ecatx1 and h1ecaty1 Beckhoff EtherCAT slow controls computers.

Due to a bug that cropped up with diaggui, the GDS tools have been reverted back to gds-2.16.5 which was used prior to this morning's update.  This affects diag, diaggui, awggui, and foton.

late entry. Restarted DAQ to capture latest Beckhoff INI files. Didnt quite get the latest files, two channels are not connecting.

8:00–8:30  Going to End X – Sheila
9:00-12:07  Working on ACB in LVEA West Bay - Mitchell
9:00-9:40   Working at BSC 1&2 looking at CPSs – Filiberto
9:00-12:07  Working on ACB in LVEA West Bay - Mitchell
13:09-      Working on ACB in LVEA West Bay – Mitchell/Apollo
13:13-15:30 Working on ITMX Chamber – Hugh
14:04-15:00 Searching for parts (cables) in LVEA - Corey
15:49 –    PSL work – Sheila

Took T240s out fo blends for ITMX Isolation; just used L4C with 100mHz blend.  Looked at local sensors.  0.5Hz peak only shows in Y3.  Toggled Gain--no change.  Zero  aha!

I see there is a large offset on this channel -7000cts Y3.  Hit zero button and the signal zeros, no change in the peak, darn.  Cycled power of Trillium interface chassis.  No change in peak.

Hey, that -7000 ct offset is back on Y3...The offset has been present essentially for as long as we've had data.  Swap cables between Trillium 2 & 3, 0.5Hz peak has moved to Corner2.  Oh boy, it looks like the Trillium.  But, we should check the cable.  Pulled cable from chamber and pins at vacuum flange look fine, reseat cable, not change, peak is still present.

Phil does continuity check on cable--there is an open conductor, Phil finds a failed solder joint at the chassis end.  He is repairing now.

The attached plot shows the 0.5Hz peak with resonances, the Y3 was the only local channel with the peak.  The other traces here are when we swapped the cables at the chamber and the peak stays with corner3.

OK looks like that was it.  Second plot below is now with the ISI back in Isolation with the Trilliums in the blend.  Same reference as above.  Top graph shows the peak on Y3 and the current horizontal local channels without any peak.  The bottom graph shows the vertical local T240 channels where we've never seen this.  The middle graph shows the cartisian X channels of asll the ISI sensors with the Optical Levers and the SUS ISI channel.  No trace of the 0.5Hz peak anywhere.  Yeah!

Thanks Jeff, Keita, Phil & Richard, Sebastian!

Last week, it was noticed a cable (D1000223 s/n S11004078, 216") for the TMS-EY Beam Diverter was BAD.  This cable was installed in 2012 & it was noted to have possible issues at that time, so we wanted to address the cable next time we had a chance.  This cable was used at a time when we didn't have our current clean/bake procedure.  I've heard this might have been a cable which was baked longer or hotter than what we now consider acceptable. 

Since this 25-wire cable is only for (1) Beam Diverter (uses 6-wires), we wanted to salvage this cable by switching other unused wires in the cable with the bad one.  The bad/shorted wire was #23; it's paired with #11.  We swapped this twisted pair with #22 & #10.  Unfortunately, this didn't work.  Hi-Pot test showed we had a new wire which was shorted to the Shield.  Since we had four more Twisted Pairs to work with, we tried it again....and again!  Sadly we kept on getting shorts with the wires.

When inspecting the wire closely, we observed tears/scuff marks on the individual wires, and exposed wire (see attached photos).  Alot of this damage was near the connector (well that's all we had exposed) but the thought is when working on the connector, one slides the connector up and down the wires.  This is probably causing the damage to the wires.  These wires are thicker than the 22awg wire.  And because of this only 17 wires fit in this connector----but it's a tight fit.  In 2012, a bad cable was inspected and found to have similar damage.  So the connector is abrading the insulation on the wires, and/or the over-heating weakened the wire insulation.

At this point, we stopped, and will now go with using a different cable (D1000225 s/n S1106887, 209").  This cable is different in that it is 28awg (vs D1000223's 22awg).  Although not optimal, it has been approved to use this cable by Rich A/Richard M. 

Andres, Sheila

After doing the PSL checks, Andres pointed out to me that the PMC power was low (1.1W reflected, 5.9 W trans).  We unlocked, and saw that the total power in reflection was 12Watts, so this must be the PMC trans PD problem again.  I went to have a look at the cable that Keita  and company connected to the PD, (alog 9338), and saw that it was connected to the scope with a 50 Ohm input impedance. It's set to high impedance now and the readback is fine, I gues we need to be carefull about that scope, does it set itself to 50 Ohm when it is power cycled for some reason?

 An ACCES Relay Card (PCIe-IIRO-8) has been added to slot 9 (Bus 1-1) of the I/O chassis for x1susex.  This is to be used for automated testing of the hardware watch dog chassis.

The GDS software has been updated to gds-2.16.9.  This includes fixes for the following bugs/enhancements:

299, 328, 389, 428 - Any combination of start, stop, and BW that result in an fft of 512 points fails, due to how the fftw library is used by diag.  Fix by changing the way the fftw plan is generated, specifying FFTW_MEASURE instead of FFTW_ESTIMATE.

497 - Add option to foton to allow specifying a SFM name along with a filter file name.  See foton man page for details on the "-s" option.

500 - Removed Kaiser Window option from diaggui, it was never implemented.

511 - Changed foton to report that no design string exists for a filter if that is the case.  Previously this was reported as a different misleading problem.

519 - Allow IP broadcast for awg, tp discovery to be specified by an environment variable (LIGO_RT_BCAST) instead of assuming the broadcast address of the workstations.  

All these changes have been built from gds/branch/gds-2.16.9.  This affects Linux and Mac OS X workstations.  Existing diag or diaggui sessions should continue to work using the older software, but at some point we need to make network switch modifications that will cause the older software to stop working.  Advanced warning will be given.

At BSC 1&2 looking at CPSs, this done now.

Alexa and I are going to the ISC racks near the PSL.  Also, I went to the X end for a few minutes.

[Jeff, Paul]

I had a look through the calibrated length and frequency paths for the IMC (IMC-X and IMC-F respectively) to check that the calibration is still in order. A description of all the filters in the IMC-X and IMC-F paths can be found in Giacomo's entry 5945.

In fact, some things were amiss in the IMC_X path:

IMC-X_M1 path:

Filters that were engaged: to_m

Filters that are now engaged: dc_cal, wresg1, wresg2, to_m

MC2 M1 feedback is not currently engaged, so this may not matter right now. However, I've engaged the filters that calibrate the IMC-X_M1 signal to M3 motion. wresg1 and wresg2 model the suspension TF from M1 actuation to M3 actuation with the resg damping filters engaged (as they are currently). If and when M1 stage feedback is applied, the corresponding IMC-X channel should be calibrated now.

IMC-X_M2 path:

Filters that were engaged: dc_cal, white, sus_d1, sus_d2, to_m

Filters that are now engaged: dc_cal, wresg, to_m

The sus_d1 and sus_d2 filters are used to model the suspension TF without the resg filter in the M1 L damping path turned on. Because we are now using the resg damping I have switched the sus_d1 and sus_d2 filters off and engaged the wresg filter, which is used to model the suspension TF with the resg filter in the M1 L damping path. The white filter is a filter which was implemented in L1 in an attempt to avoid digitization noise above 50Hz (since the signal is so small there). I don't think we want to have this filter engaged, since it has to be accounted for later in data analysis, and I think we can ignore IMC_X so far above the L to F crossover. I've therefore disengaged this filter. This isn't the first time this one has come back to haunt us: see e.g 5311 or 5452.

IMC-X_M3 path:

Filters that were engaged: dc_cal, white, sus_d, to_m

Filters that are now engaged: dc_cal, wresg, to_m

Same story as for the M2 path.

I took a snapshot of all IMC-X filter banks.

IMC-F path:

Filters that were engaged: cts2V, InvGenFilt, VCO, FtoL

Filters that are now engaged: cts2V, InvGenFilt, VCO, FtoL

The only filter that changed since Giacomo's entry 5945 is the FtoL filter being engaged now instead of the tokHz filter. This means that the IMC_F signal is now calibrated in meters, presumably for ease of comparison with IMC_X. I checked the VCO gain filter: it is still the 536,604 Hz/V value, agreeing with Kiwamu's number from entry 5556 after accounting for the double pass of the AOM.

Still no resolutions to the problems with HAM4 ISI transfer functions. I took more DTT tf's today, and they all look a little better than the Matlab tf's. The attached plot shows the 3 vertical pods. The 3 thinner lines are the Matlab tf's (which, though not shown, have been repeated 3 times, all 3 times look pretty similar) and the 3 thicker lines (red, green and blue) are the same sensors with a DTT whitenoise tf.