Sheila, Daniel

Today we increased the power from the laser onto the fiber locking BBPD, from 1mW to 9mW.  We first tried 25mW, but we might have been overdriving the phase frequency discriminator with that much power, the pll was able to lock but with a lot of excess noise.  With 9mW we get a large enough beat note that the frequency comparator is working well, but we do not see excess noise on the beatnote on the RF analyzer.  (will double check RF level in the morning)  This means that the autolocker is now working for the PLL.  Daniel also changed the attenuators for the VCO input to the frequency comparator, I think to 20dB ( I also need to double check this in the morning). 

We also looked into why the photodiode gains were not changing.  The power supply in the beckhoff unit for that chassis was not connected to the modules, so none of the binary outputs were working.  After we connected them we adjusted the calibration of the fiber trans, IR laser monitor, and fiber polarization monitor PDs, which we originally did taking into account the non working gain settings.  

We also found a on Track QPD to monitor the beam position on the green refl diode.  I replaced the HR steering mirror in the path the the PD with a 80% reflector, to make a pick of for the QPD.  We had completely lost the return beam, presumably because of seismic commissioning, so we didn't align this yet.  

[Stefan, Kiwamu]

We adjusted the phase difference (e.g. LSC-REFL_A_RF9_PHASE_D) of all the REFL and POP demodulators except for a WFS channel which showed suspiciously small signals.

Observations on the I/Q relations:

We discovered that the amplitude imbalance between any pair of I and Q were good and were typically less than 0.5%.  Also, the extra imbalance that can be introduced by changing the whitening settings are almost comparable to 0.5% and we concluded that it was pointless to correct the amplitude imbalance at this point unless the whitening settings are fixed. Therefore we didn't attempt to correct them this time. On the other hand, the phase difference was not as sensitive as the amplitude imbalance to the whitening settings. They were found to be typically off by a couple of degrees from 90 in the first place, while changing the whitening settings didn't rorate them more than 1 degree. This is the background story of why we ended up adjusting only the phase differences.

One demod board doesn't look healthy:

In the process of the adjustment, we found that channel 4 of the WFS REFL_B_RF9 demod board (SN:S1000994) displayed too small signals in both I and Q by a factor of 2-ish in their amplitudes compared with the rest of three channels. We must pull this board out of the rack and take a close look in the EE shop.

Adjustment of the phase difference:

We used the same technique as Anamaria did at LLO (see LLO 6829). The RF frequency was set apart by 40-50 Hz from the LO frequency in each demodulator by using an IFR RF source. The RF level was at -40 dBm for the LSC demods and -41 dBm for the WFS demods. None of the whitening stages were engaged. The whitening gains were simply set to be their maximum (i.e. 45 dB) during the measurement. The belows are the results:

* * * in-vac 1f

H1:LSC-POP_A_RF9_PHASE_D       87.30
H1:LSC-POP_A_RF45_PHASE_D      92.93
H1:LSC-REFL_A_RF9_PHASE_D      88.63
H1:LSC-REFL_A_RF45_PHASE_D     92.98

* * * in-air 1f

H1:LSC-POPAIR_A_RF9_PHASE_D    87.78
H1:LSC-POPAIR_A_RF45_PHASE_D   92.95
H1:LSC-REFLAIR_A_RF9_PHASE_D   88.27
H1:LSC-REFLAIR_A_RF45_PHASE_D  92.98

* * * 2f and 3f

H1:LSC-POPAIR_B_RF18_PHASE_D   89.17
H1:LSC-POPAIR_B_RF90_PHASE_D   91.05
H1:LSC-REFLAIR_B_RF27_PHASE_D  91.39
H1:LSC-REFLAIR_B_RF135_PHASE_D 84.49
 

* * * WFS REFL 9

H1:ASC-REFL_A_RF9_SEG1_PHASE_D 88.28
H1:ASC-REFL_A_RF9_SEG2_PHASE_D 88.34
H1:ASC-REFL_A_RF9_SEG3_PHASE_D 88.55
H1:ASC-REFL_A_RF9_SEG4_PHASE_D 88.55
H1:ASC-REFL_B_RF9_SEG1_PHASE_D 89.17
H1:ASC-REFL_B_RF9_SEG2_PHASE_D 88.32
H1:ASC-REFL_B_RF9_SEG3_PHASE_D 88.64
H1:ASC-REFL_B_RF9_SEG4_PHASE_D 0
 

* * * WFS REFL 45

H1:ASC-REFL_A_RF45_SEG1_PHASE_D 91.96
H1:ASC-REFL_A_RF45_SEG2_PHASE_D 93.15
H1:ASC-REFL_A_RF45_SEG3_PHASE_D 92.37
H1:ASC-REFL_A_RF45_SEG4_PHASE_D 93.18
H1:ASC-REFL_B_RF45_SEG1_PHASE_D 92.80
H1:ASC-REFL_B_RF45_SEG2_PHASE_D 91.65
H1:ASC-REFL_B_RF45_SEG3_PHASE_D 92.88
H1:ASC-REFL_B_RF45_SEG4_PHASE_D 93.00
 

Reduced the drive on the transfer function for HEPI in the 500 to 1000 hz band.  We've experienced a trip for the L4C everytime the TFs would get to the V4 drive.  I can't find an unusual drive (DC level) here relative to the other drives nor an obvious L4C response difference--the L4Cs all look the same to back ground input and the Actuators all displace the IPSs about the same.  The corner 4 L4Cs both H & V do seem to respond more greatly to all the drives than the other corners do; but the others do have varying levels of response to the drive on the different corners.  The response to V4 drive at V4 is just the strongest.  I reduced the drive to 0.5 (from standard 1.0) and it made it through.  I increased it to 0.75 and it tripped but only on the second iteration.  So I'm running the TFs now with this mod (gain=0.5) from previous chamber commissions.  Maybe there is a loose bolt somewhere?

Attached is a plot showing the L4C responses as the TFs go through the drives.  The Drives run H1 H2 H3 H4 V1 V2 V3 V4 although I've got them jumbled in the plot.  But you can use this to see how every corner is responding to the 8 local drives.  The WD trips as soon as V4 starts so you can work back through the plots to get your bearings of where things start.  It is interesting when you realise the response on a corner/HorV isn't necessarily the largest when that corner/HorV is driving.  For instance, V2 responds more greatly to the H2 drive than it does to the V2 drive.

LVEA Laser Hazard

08:57 Apollo at End-X setting Optical Lever piers 
09:10 Praxair delivery to CP-3
10:09 Thomas at End-X working on Optical Levers
13:18 Kyle working on vacuum pumps at End-X
15:02 Gerardo moving baffle parts into the LVEA

The ISI is damped only.  There are two matlab sessions working this running on opsws0.  Thanks for letting this run (overnight likely.)

HEPI TF's running over-night on ITMX. Opsws1.

Existing cable needs to be re-routed to make room for new oplev pier but it is too short -> Replaced short cable with long one borrowed from the Corner Station turbos 

I tested the minimal interlock functionality (QDP80 PUMP RUNNING) of the new cable by demonstrating that the turbo safety valve closes when the QDP80 is stopped remotely with the safety valve in the "ROUGH" or "TURBO" position.  

I did not test the other signals used on this cable, i.e.,  "QDP80 TEMP WARNING", "QDP80 TEMP HAZARD" and "N2 FLOW WARNING"

I noticed that the ODC channel for the IMC was not happy. Tracked it down to some saturation in the WFS A and B inputs, presumable due to the input power increase.
I lowered the whitening gain lowered to 36dB (was 45dB).

I also readjusted some thresholds on the IMC ODC screen:
H1:IMC-ODC_DOF[1|2]_[PIT|YAW]_ERR_MAX 10000
H1:IMC-ODC_MC2_TRANS_SUM_MIN 2000
H1:IMC-ODC_IM4_TRANS_SUM_MIN 15000

A temporary RF power splitter was installed in both REFLAIR_B and POPAIR_B RF paths. They will be replaced by diplexers once they are ready.

The attached is a picture of the RF power splitters installed on the ISC R2 rack. In some future, we might add RF filters in order to cut off unnecessary RF signals.

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See attached for the watchdog trip plot.  Interesting in that the T240s see a slow tilt on horizontal channels and this trips the system.  There is a 4.9 EQ about 26minutes prior south of South Africa but it is shallow and maybe too small/too far...  May not be related.  I've put the ISI back in lvl2 isolation.

I adjusted the demodulation phase of the REFLAIR_A photodiode in the delay line phase shifter by toggling the physical switches on its front panel.

Right now, the phase is adjusted such that the length signal from the power recycling cavity shows up in Q which is opposite to the usual signal convention. Because the phase shifter could rotate it by roughly 100 deg at 9 MHz which was not big enough to get the I signal maximized for the power recycling signal, I ended up with the Q signals maximized. The adjustment was done by letting the PRX cavity freely swing and taking a look at the I and Q monitors of the demodulation board with an oscilloscope. The attached is a picture of the resultant physical switches after the adjustment. Note that it is set to be the internal switch so that the digital system can not mess it up.

I don't feel comfortable with the degree to which GV5, GV7 and GV20 are "soft-closed" for the unattended worst case scenario -> Switched YBM turbo from being backed by its QDP80 to the safer state of being backed by the LD which has its own, redundant, energize-open isolation valve -> valved-out XBM turbo 

The solenoid-actuated air manifold which switches instrument-air from either the bottom or the top of GV7's piston leaks unpredictably when the applied air pressure is low, i.e. with the nominal 5 psig applied when GV7 is soft closed.  For instance, if the regulator is isolated from the manifold and an output of 5 psig is selected this pressure falls to 0 psig when valved-in to the manifold and stays 0 psig regardless of how much time elapses.  If the applied pressure is increased the audible "hissing" past the leak increases but the piston pressure remains 0 psig - to a point. If the regulator output pressure is further increased eventually the pressure at the piston will "come on scale" but the leak rate will often change simultaneously and then the desired pressure applied to the piston will be exceeded and GV7 may cam hard-closed etc. (GV5 doesn't do this)

I moved the newly assembled scroll pump+sentry valve+relay box assembly out to the X-end station and am running it in standalone mode to get some hours of running on it before using it in place of the X-end turbo's QDP80 -> Once in use, the failure mode for the X-end turbo will have two layers of protection.  

References: D1201036 (BSC9 ACB assy) and D1200314 (BSC3)

Gerardo read the distances between the baffle diodes off of CAD drawings for me (see the attached cartoon). 

ITM baffle PD1-PD4 separation is 11.3" over 4km (72 urad) both horizontally and vertically. For ETM the number is 11.8", so it's 75 urad.

Don't know why the patterns are different for ETM and ITM, but using these we can calibrate TMSX, ITMX and ETMX bias sliders. Note the factor of 2 between TMS and mirrors, this is because TMS moves with the beam but mirrors don't.

Calibration of ETMX is somewhat suspect (at 10urad level) because of the fact that the position loop of EX ISI got accidentally off before I did ETMX adjustment.

Attempted to reengage the ISI Isolation with the added tilt of HEPI.  This HEPI tilt swings the ISI such that the current free hang location of the CPS is too far from the previous position.  The T240s ring up and trip the process.  I attempt to get there by first setting the Current Setpoint to current location (there's a button for this) and of course that worked until the latter part of the script tried to drive the CPS back to the free hang position.  So, I then further pushed the Current location into the Target position.   This of course did work cause it basically drives the ISI nowhere and doesn't kick/tilt the T240.  But, the ISI now operates in this tilted position.  To get it back we'd just need to untilt the HEPI and reset the ISI setpoints and targets.

Back to the Isolation operation, last Friday JeffK & I noticed the ISI drives growing after being at lvl3 isolation.  These rang up and tripped on Actuator drive levels.  I set the ISI to lvl1 isolation and pulled out a book.  No noticible ring up after several minutes.  So I controlled down and went up to lvl2 isolation.  Again, several minutes and no problem.  Not sure if I waited long enough but...

Then I ctrldown and put it in lvl3 isolation.  Sure enough boost2 was engaged rather than boost3.  I left it be and after running pretty well about 15 minutes the drives started to ringup mostly in Stage2 Verticals but other channels as well.  I ctrldown next and then brought it back to lvl3 again but now switch from boost2 over to boost3 right away.  Again the drive rung up after about the same amount of time.  I should have been watching the spectrum before it rang up but I again had dtt troubles.  When I did get it running the drives were already excited.  Looking at the spectra I saw a tall peak at 147hz.  I then did a ctrlDown and saved the trip.  As the spectra quieted down, the 147hz peak withered.  Better to see this pop up while steady state rather than disappear after ctrlDown but it maybe what is happening.  One thing I notice in the trend is that it looks to stop increasing in amplitude after a time.  See attached.  Maybe it would settle back down or maybe it eventually trip the watch dog but I didn't give it that chance this time.

In the attached plot you see the Master Drive going up and down as the isolation is engaged and ctrlDown'd.  The lvl3 isolation is the last two wider segments.  Notice the ramp up of the signal stops after a time and goes flat before I ctrlDown.  Again so very interesting...

I've set the isolation to lvl2 for now; looks OK after about 20 minutes.

LVEA Laser Hazard

Apollo - Install HAM1 door
Hugh – End X to work on HEPI  

08:30 Keita transitioned LVEA to laser safe while Apollo crew installed the HAM1 door
09:45 Apollo finished installing HAM1 door
10:45 Keita transitioned the LVEA to laser hazard
11:00 Hugh & Mitch at End X to work on HEPI
11:50 Dave did a remote DAC recycle to pick up new Beckhoff channels

Merry Christmas to one and all

The photodiode amplifiers for the fiber transmitted and rejected beams were not behaving as expected. Changing the gain had seemingly no effect on the read voltage. The first problem was that the two diodes were crosswired in the slow controls system. However, this did not fix the problem, and it is the same for the IR DC power. It looks like the gain settings are not getting applied to the concentrator. The main suspects are the 5V supply, DC_6, in the end 2 chassis, or another of these DB37 cables with pin 19 conveniently left unconnected. This supply is used to power the binary IO terminals for auxiliary concentrator 5. It also controls the gain in the REFL PD DC path.