Gerardo, Mitchell,

Yesterday Gerardo removed parts and hardware from the Cryo baffle assembly and moved them to the LVEA for the ITM-Y assembly. Today he and I installed the Eddy current dampers thus completing all work (for the Cryo baffle) at the end station. 

The HEPI XFs are done for the moment so these have been put back into running state

ITMX HEPI is on but doing nothing.  ITMX ISI is in DAMPING only state.

ETMX HEPI is on and tilting -12000 Ry.  ETMX ISI is damping and isolating at lvl1.  I may push this up to lvl2 to see how it survives.

Overnight TF's on ITMX HEPI were mostly succesful, but it looks like we have an issue with instrument pods, or associated rack chassis in one of the corners. All of the IPS's and L4C's in corner 3 on this chamber look bad. Power spectra also don't look great.

See the attached files for the XFR plots.  All the channels look similar with good coherence.  These are local to local with IPS and L4C responses.

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.

a

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.