4 am reading (torr) 

PT243 -  1.08 x 10-9
PT244 -  1.42 x 10-9 
PT210 -  1.43 x 10-9

2 am reading (torr) 

PT243 -  1.09 x 10-9
PT244 -  1.45 x 10-9 
PT210 -  1.45 x 10-9

12 am reading (torr) 

PT243 -  1.12 x 10-9
PT244 -  1.48 x 10-9 
PT210 -  1.48 x 10-9

10 pm reading (torr) 

PT243 -  1.13 x 10-9
PT244 -  1.50 x 10-9 
PT210 -  1.50 x 10-9

Note: time stamp of site overview different by two hours from Chandra's last entry yet same values 

8 pm reading (torr) 

PT243 - 1.13 x 10-9 
PT244 - 1.50 x 10-9 
PT210 - 1.50 x 10-9

Tonight I moved the power recycling cavity axis around to try to center the spots on the ITMs.  I was moving PR2 around, and the IFO's ASC followed me.  It was a pretty significant move - enough that we no longer had green hitting the transmission cameras at the vertex.  The carrier power recycling gain never really changed, but the sideband recycling gain decreased.  I couldn't seem to recover this, even by moving the input beam (IM3 and a little IM2), so I have to think more about this.

Anyhow, when I tried to increase the power from 12W to 15W, I saw the ~0.5Hz pitch oscillations that Sheila describes in alog 26367. In general, the ASC loops are stable, however as we saw last night, it's very hard to get any coherence right near this peak, so I can't say for sure that we don't have a loop issue. 

Big EQ in Japan, so we're calling it an early night.

Michael, Krishna

Today, we changed some parameters which correct for pixel-level non-linearities in the CCD. This improved the noise in the BRS-2 output.

We also improved several error-handling features of the code and created the Status signal (the 4th channel going in to SEI), which is set to have the following states: Good (5V), Damping On (2V) and Bad (0V). In the near future, there will be several other more detailed states on the BRS model screen indicating the specific problem, if it is in a bad state, which will help debug the problem. Detailed documentation on this will be prepared soon. We also filled out some of the filter banks for processing the BRS-2 data and for tilt-subtraction. More on that in the future.

The first attachment shows the BRS-2-rX signal in comparison to the STS2-Y seismometer on the ground close to it. The data is converted in to displacement units and was measured with low wind speeds on the order of 2-3 mph. The next page shows the coherence between the sensors. The instrument is still drifting and settling, so the low-frequency noise will improve over time.

We noticed that there may have been some excess noise in BRS-2, especially at higher frequencies, due to aliasing from the high frequency spikes (30, 80 Hz). Therefore we lowered the software low-pass corner frequency from ~50 Hz to 10 Hz. This does introduce phase-loss at ~few Hz but since this sensor is primarily used at ~10-500 mHz, this shouldn't be a problem.

The second attachment shows the output of BRS-2 after the improved low-pass.

6:00 pm reading (torr) 

PT243 - 1.11 x 10-9 
PT244 - 1.45 x 10-9 
PT210 - 1.45 x 10-9

We have an oscillation in H1 that has been with us for a long time, is not understood, and can be mitigated by moving alignment offsets, and gets worse at high power.  All the information in this alog is elsewhere in the log, this is just a summary.

For about 6 months we didn't change our soft loop offsets because when we did we would get the oscillation, this is how we stayed stable through O1.  The main symptom is that the pitch optical levers move at frequencies around 0.45 Hz, all in phase with each other, and if you look at the relative sign of the optical levers it looks like CSOFT motion. the POP and arm transmitted powers also oscillate. Now that our soft loops are working again, we are probably in a position to again tune the soft loop offsets to be stable at 20 Watts, but it seems like this won't be a great solution as we try to increase the power even further. 

There have been many alogs about this, but I wanted to summarize some of the recent things we have looked at. 

It seems like the torque that moves the test masses isn't coming from any of the arm ASC loops, or the optical lever damping.  The first screenshot shows this, this is from Tuesday night when we powered up several times in slightly different configurations and repeatedly saw the same size of oscillation.    The solid lines here show what was our normal configuration before Tuesday, with ITM optical lever damping on and ETM optical lever damping off.  The dashed lines show the test configuration, where we added notches to the soft loops that reduce the actuation by about a factor of 100 at the oscillation frequency, and lowered the CHARD gains by a factor of 10. You can see that in the test configuration we also have about 5 and a half times less DHARD drive in the test configuration than in the normal one.  Since all of these ASC drives are smaller in the test configuration but the oscillation is about the same, it seems like the force that moves the test masses must not be from these control signals. 

It seems like the fluctuating radiation pressure due to changes in circulating power alone can't provide enough torque.

In the attached matlab script I estimated the miscentering we would need on each optic so that the approx 900 W changes in circulating power we see during the oscillation could provide the radiation pressure torque.  These are way too large, ranging from 8-33 cm on the different optics.  As a sanity check I also assumed that the alignment shift we see powering up before the soft loops get a changce to correct is due to radiation pressure (which it may not be).  From that I estimate miscenterings ranging from 0.5-3 cm. I used the moment of interias from Evan Hall's alog , which he tells me are slightly wrong but not enough to matter.

The oscillation frequency does seem to depend on circulating power

The evidence for this may be a little shaky since it is hard to get enough cycles of the oscillation to get a spectrum with nice resolution, but the second attached screen shot shows a spectrum of ETMX optical lever pit for 3 different circulating powers.  These circulating powers are based on Dan Hoak's calibration and the TR XB QPD.  The frequency of the lower two powers is the same within the resolution of my spectra. This may not hang together perfectly because I have included a little bit of time when we were powering up or down in the spectrum.

Other ideas?

We have also tried putting a resonant gain the DARM loop(no impact), changing A2L feedforward (no impact), and centering on the ETMs (improvement).  One possible test we could try to understand this better would be to drive the laser intensity and see if we can produce angular motion.  

State of H1: locking and making it to DC Readout

Site Activities:

• John and Chandra to LVEA vertex - vacuum
• Bubba to MX, MY, EY chiller yard - vent prep and chiller work
• Richard and Ed - EY and EX - electronics survey
• Fil - LVEA - vent prep
• Betsy and Travis - OSB optics lab
• Karen and Chris to MY and MX - cleaning

H1 Activities:

• TJ worked on new Initial Alignment Guardian code in the morning
• Initial alignment was done
• Locking went well with a pause in DRMI and Engage ASC part2
• At the end of the shift, H1 was in DC readout and in the hands of the Commissioners

Possible Activities for tomorrow:

• Filiberto - End Station - work on hardware for parametric instability - will effect QPDs, so will prevent locking
• Vent prep continues

4pm readings (Torr)

PT-243: 1.08e-9
PT-244: 1.42e-9
PT-210: 1.42e-9

John, Kyle, Chandra

Testing a three day cycle on CP3 overfill. We will *not* fill CP3 today and instead monitor pressures overnight, and fill tomorrow, Friday. 

Chandra time (local): 16:00, 20:00, 00:00, 4:00
Kyle time (local):  18:00, 22:00, 2:00, 6:00

The HAM ISI model updates Tuesday, alog 26321, allow the suspension motion calculation to be done by the ISI.  The filters and matrices to convert from ISI GS13 cartesian basis to the optic euler basis are now filled.

The BSC ISIs were updated for this earlier in the month.  Alogs: original model updates-25913, ISI vs SUS calibration filter- 25993, mods for multi sus plarforms- 26117, library part cleanup/corrections- 26128, BSC filters & matrices populated- 26132, svn commits- 26143.

DetChar can now start pointing to these ISI computations.  Look at channels: H1:ISI-{isi platform}_SUSPOINT_{suspension}_EUL_{euler dof}MON.

euler dof is L, T, V, R, P, orY

isi platform is HAM2, 3,..6, ETMY, ETMX,..,BS

suspensions available are ETMY, TMSY, ETMX, TMSX, ITMY, ITMX, BS, MC1, MC2, MC3, PRM, PR2, PR3, IM1, IM2, IM3, IM4, SRM, SR2, SR3, OMC.  Of course you have to get the suspension on the correct isi platform.

Attached is a snapshot of the medms: the GS13 filter bank and available suspension calcs are accessed from the ISI Chamber overview; the transformation matrices are accessed from the calc screen.

[Fil, Jenne]

We've measured the distances from each Newtonian array sensor location (marked on the LVEA floor with green electrical tape) to the racks we'll use for signal concentration, so that we can order our cables soon. 

We've had much more success tonight with the non-broken Xarm Trans QPD.  We once again re-centered the spots on the ETMs, although they didn't need much moving.  We are able to sit at 10W and 12W just fine now.  Now, we're running into regular ol' loop oscillations, so we've been measuring loops at different powers, and trying to re-tune them. 

CHARD Y seemed the most egregious, so we created a new control and boost filter combo, which live in FMs 4 and 5.  Unfortunately, these filters are totally unuseable at 2W, although they improve our stability at 10W, so right now the guardian still only engages the old loop shape filters.  We'll have to re-think the 2W filter situation to make sure we can transition between these filters.  Right now, we were by-hand turning off the CHARDY loop, changing the filters, then re-engaging the loop.  Attached is an open loop gain for the new loop.

PRC2 pitch we've decided is kind of okay if we use a factor of 2 less gain.

Now, we're seeing oscillations that also show up in AS 90, so we suspect either the MICH or SRC angular loops.  Unfortunately, there's something going on with NDS/the lockloss plotter/something, such that I can't get data from the last ~5 locklosses.  The ones before that, I can still get and plot, but it can't find data for the last several even if it's been an hour since that lockloss. 

So, next up:  Measure the MICH and SRC loops at 10W to see if they're close to unstable.  Measure again at 15W, and then think about going from there.

(Tasked by Aidan)

We were curious of how the HWS sled power decrease over time so we know when to swap them out. Below I've attached plots of HWSX and HWSY sled power (corrected for gains) and input current. The start time is when we replaced the SLED (April 26, 2015 for YSLED and March 1, 2016 for XSLED). I only plotted the time when the SLEDs were turned on (displays in number of days). XSLED shows deteroration of ~2% per day and YSLED shows deterioration of ~1% per day (given 7mW to be 100%, I don't think we are shooting 7mW out though but the trend looks reasonable). YSLED power decreased slightly faster when the input current = 94 mA.

XSLED data can be found here and YSLED data can be found here. The column goes Time|Power (mW)|Current(mA). The script to fetch and plot data can be found in the same directory.

The fast decay in the beginning is a known problem.

J. Kissel, B. Weaver, H. Radkins, D. Barker, J. Batch

Here's a list of all of the upgrades we were involved in today. There will be more details of the upgrade, more debugging, associated MEDM screen changes, svn commits, and other clean up tomorrow as we continue to explore what we've installed and debug. Bear with us, and thanks for your patience.

1) Fixed UIM coil driver path's automatic compensation bug by updating CD_STATE_MACHINE.c. See Int. Issue 1178.
2) Installed ISI GS13's projection to SUSPOINT Euler basis projection into the SEI models. See ECR E1600028.
3) Sent the Euler Basis Longitudinal DOF for each SUS involved in a cavity over various IPC (PCIE and RFM) and models (ISI, End-station PEM, H1OAF) to be collected in OAF. See ECR E1600028.
8) Removed the excess RFM channels from End-Station ALS models (noteably *not* the excess channels in the ISC models). This made room for 3). See LHO aLOG 25216
4) Added various rotational sensor correction paths to the BSC ISIs (GND BRS to ST1, and ST1 to ST2). (Prototyping, this stuff, no ECRs just yet)
5) Removed the L4C sensor correction path. See SEI aLOG 666
6) Added new infrastructure for the EY BRS. (Most Copied from EX, covered by ECR E1500246)
7) Reverted the BSC SUS's coil driver monitors to store the NOISEMON in the frames (and pushed the FASTIMON to the commissioning frames). Also, we put filter modules in front of the NOISEMONs (like was done for the FASTIMONs the last time we touched this) in case we ever wish to calibrate them. See ECR E1600033 and LHO aLOG 26313

Because we haven't built MEDM screens and actually *used* any of these paths yet, there's still potential for bugs and we haven't explored and/or fixed all of the collateral damage. Stay tuned as we continue to work on all of these updates tomorrow.