Richard called saying the laser was off when he entered the Control Room this morning.

    According to the laser status screen, the laser tripped due to a crystal chiller flow rate
error, somewhere in the power meter circuit.  Attached are two plots of the previous one day's
trend data.

    The signal from head 2 is somewhat noisier than the signals for the 3 other heads.  Looking
back even further it seems to have been that way for at least the 6 days.  Unfortunately we do
not have enough diagnostics to pinpoint the location of the potential blockage and at this point
in time it is a bit of a waiting game unless time is scheduled for invasive maintenance.

    After restarting the laser at ~06:30, things seem to have settled down by 06:40.

I set up a magnetometer at EY near the ESD chassis in the VEA for a blip glitch study (see upcoming log from Paul). The plot shows the channel names (12 and 13 are the Y and Z axes) and very high coherence between the mag and DARM at odd harmonics of 1 Hz. This is one of the new combs that Ansel identified and so this channel may also be useful in seeing if it goes away during the reboots on Tuesday.

Carl, Evans, Stefan,

We had h1ecatx1 crash. A reboot didn't bring back the connection - we had to log in and manually start start.bat.

Then we ran into strange guardian behaviour, which was tracked down to epics channels having different values on h1guardian0 and operator machines.

In particular, on h1guardian0:

In [8]: ezca['ALS-Y_LOCK_ERROR_FLAG']
Out[8]: 1
 

while on operator 0 I get:

In [7]: ezca['ALS-Y_LOCK_ERROR_FLAG']
Out[7]: 0

 

Matt, Stefan

The switching of coil drivers to low noise takes quite a long time with the current guardian code (20+ seconds per coil, with 20 coils, so over 400 seconds or about 7 minutes).  This guardian state has recently been updated to make it more responsive (moved code to run, and used timer rather than sleep, see 28353), but this didn't make it any faster.  I just changed the code to switch all of the optics together, rather than do them serially (see below).  This should reduce the total time to ~90 seconds.  The old function is still in ISC_LOCK.py as COIL_DRIVERS_SLOW.

We have not locked yet, so this code is untested. 

=============================

=============================

Matt, Stefan

In an attempt to find our missing power, we decided to look for a change in the light scattered from the TMs.  The general idea was to use the camera images normalized to the input power, and see if the scattered light changed or increased faster than the arm power.  (A change in scattering could indicate heating of the mirror surface by a small absorber which leads to deformation and increased scatter T1000154).  This is similar to the OL test done earlier.

To investiage this and avoid camera saturation issues, I made a script to grab images of the TMs at a variety of exposure times (mexp.py).  This script takes 5 snapshots of each TM with exposure times from 30 to 10000 (micro seconds?).  I ran it during several power-up sequences to get images at 2W, 10W, 20W, 40W and 50W (all in /ligo/data/camera).

The accompanying matlab code loads these images and uses them to make a high dynamic range image (HDR) for each TM at each power level (see attached PNG for 40W images, and attached mat file for 2W and 40W data).

The overall conclusion is that the scattered light scales with the arm power.  That is, there is no evidence of increased scatter loss at higher power.

(About the HDR image: these use a log-color scale.  The ITMY scatter seems to be much larger than other optics.  ITMX has a strange crecent shaped collection of scatters.  The ETMs look like the usual stary night, though ETMY could use some focus adjustment.)

Quick Summary: Commissioning. Carl's working on PI, Stefan's working on PUM and RF45, and Matt's making pretty pictures. The goal tonight was to make sure ITM PI damping works. We locked at 40W for couple of hours.

- Added PUM coild driver switching to state 3 for 4 test masses into LOWNOISE_ESD_ETMY (at the end). It seems to take the transient.

- Down state switches back to state 2.

- Moved the pdList and pdSqList for the RF45 modulation depth lowering to the lscparams file.

- Updated the DOWN state to reset the gains of the PDs in pdList and pdSqList.

Optical lever sum sees the large angle scattering from the test mass it looks at (see T1600085 for details, but note that the trans impedance and whitening gain in that document are not confirmed by measurements). This is a tiny thing compared with the power of the OL beam itself, but the scattered light is visible if you subtract the background OL beam.

I looked at the time series of OL SUM for four test masses together with MC-PWR_IN_OUT16, ASC-X_TR_B_SUM_OUT16 and ASC-Y_TR_B_SUM_OUT16 between Jul 12 23:35:44 and Jul 13 1:4:44 2016 UTC.

The first attachment is the (OL SUM -background)/TRX (or TRY), rescaled such that they are 1 at 10W. I cannot see any huge increase in large angle scatter as the IFO moves to 40W for any of the test masses.

The second attachment shows you just how the raw-ish data looks like, this is after removing the OL beam offset and taking into account the whitening gain and trans impedance. There's some difference between ITMs and ETMs but note that ITM OLs are about 5 or 6 times farther away from ITMs than ETM OLs are from ETMs.

I removed the 300 Hz and 600 Hz stopband filters in DARM, along with the 950 Hz low-pass filter.

I increased the gain from 840 ct/ct to 1400 ct/ct, giving a UGF of 55 Hz. This seems to have improved the gain peaking situation around 10 Hz (see attachment).

The new settings have been added to the guardian (in the EY transition state), but have not been tested. The calibration has not been updated.

repost, somehow the original was erased during edit testing

The DAQ test stand timing components which includes the timing fanout, IRIG-B, and the powered-up I/O chassis have been reprogrammed to a version of the firmware which eliminates flahsing of LEDs when the components are sync'ed.

The wind direction part of the anemometers still seems to not be reading correctly.
There was some discussion on the SEI call today that maybe it had started working, but a look at the DetChar page at
https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20160714/pem/wind/
shows good info for wind speed, but nothing sensible for wind direction.

I put some data into the SEI log about wind direction as seen at the Tri-cities airport. 
https://alog.ligo-la.caltech.edu/SEI/index.php?callRep=1035
The FAA and Jim agree that strong winds come from the southwest. 

Kiwamu, Stefan

Using the pr2spotmove script (see alog 28420), we moved the spot on PR2 in lock by almost 1 milimeter.

Conclusions:

- The carrier recycling gain desn't care about the PR2 spot positon.
- The POP beam from PR2 to the invacuum POP diode is fairly close to the edge of the visibility aperture. This might be an issue for LSC aux noise.

Details:

- To be able to explore the full range of motion, we had to switch back to the REFL B WFS for PRC2 / PR3 control. We BTW verified that this WFS also works at 40W (and during the power increase).
- With that, the move-limiting aperture is the path from PR2 to POP. We can move until the POP_A loses the beam. The pitch and yaw min/nominal/max values for PR3 alignment angles are
    Pitch value / delta:
     min: -302.95  / -4.6urad
     nom: -298.35 / 0urad
     max: -275.35 /  +23urad
    Yaw value / delta:
     min: 257.45 / -16urad
     nom: 273.45 / 0urad
     max: 281.45 / +8urad
  Notice how close to the edge we are in pitch - this could be a factor for PRCL/SRCL/MICH auxiliary length noise and scatter coupling. We have to revisit this in low-noise.

- The 27.6urad move in pitch (24urad in yaw) peak-to-peak move corresponds to 0.9mm (0.8 mm) for the PR2 spot position. Note though that for the beam in transmission of PR2 that corresponds to several spot sizes of motion. (The virtual beam waist behind PR2 is 114u, i.e. we moved the spot more than 7 beam waists. As a result the beam completly left the POPAIR camera view.)