Gerardo & Hugh

We recentered these oplevs to make better use of their tracking.  And especially HAM2 as it seemed to be way off on one quadrant.  Luckily we didn't lose the beams.

First attached is a three day trend showing yesterdays fun with HAM2 and the recentering this morning.

Next is the last eighty minutes, maybe given the wandering, the X-Y plots on the medm should have their window zoomed out some.  This seems to be an issue mostly on HAM3 Yaw.

The third plot shows the five hour detail around yesterday morning on HAM2 with the HEPI Cartesian RZ (yaw) RY (pitch) and HP, the horizontal pringle mode.  This further shows even though the HEPI RZ has servo'd back to its reference, the OpLev Yaw would disagree.  Likewise, even though the HEPI pitch shifted way off for most of the time and then came almost all the way back, the OpLev Pitch doesn't follow that in any reasonable way.  Even though these OpLevs have no caibration as I understand, this says alot about system distortion.  I've included a feducial from the large shift in the HP calculation but it doesn't appear to correlate to anything in the OpLev response.

I wanted to try turning on HEPI sensor correction at EY this morning, but I've run into an issue. When I turn on just the new Mitt_sc filter no numbers come out of the outputs. However, when I turn on the filters associated with the fir sensor correction, numbers come out. Even when I just turn on the path, with no filters engaged, numbers come out of the output block. Something about engaging the sensor correction filter completely cuts the signal. I will try copying the filter to a different fm when I get a chance.

As the wandering laser intensity continues I intend to learn more about these systems. I can only report the findings and make the adjustments. ISS diffracted power is down to ~5% this morning. REFSIGNAL was at -2.04V as it was set by me yesterday. Today I have adjusted REFSIGNAL to -2.02V to bring the diff power to ~8.6%. Attached is a past 5 day trend. the spikes, i am told,  are likely caused by activations on MC2? (for example)

model restarts logged for Tue 04/Nov/2014
2014_11_04 09:13 h1suspr3
2014_11_04 09:18 h1susbs
2014_11_04 09:18 h1sussr3
2014_11_04 09:20 h1susitmx
2014_11_04 09:22 h1susitmy
2014_11_04 09:24 h1susetmx
2014_11_04 09:25 h1susetmy
2014_11_04 09:41 h1lsc
2014_11_04 09:46 h1broadcast0
2014_11_04 09:46 h1dc0
2014_11_04 09:46 h1fw0
2014_11_04 09:46 h1fw1
2014_11_04 09:46 h1nds0
2014_11_04 09:46 h1nds1
2014_11_04 10:34 h1calex
2014_11_04 10:35 h1caley
2014_11_04 11:12 h1iopoaf0
2014_11_04 11:12 h1pemcs
2014_11_04 11:14 h1oaf
2014_11_04 11:14 h1odcmaster
2014_11_04 11:14 h1tcscs
2014_11_04 12:36 h1broadcast0
2014_11_04 12:36 h1dc0
2014_11_04 12:36 h1fw0
2014_11_04 12:36 h1fw1
2014_11_04 12:36 h1nds0
2014_11_04 12:36 h1nds1

no unexpected restarts. Maintenance Day. Jeff SUS and LSC model work (with associated DAQ restart). Dave CAL work (with associated DAQ restart, plus latest Guardian and Beckhoff EDCU channels)

Greg, Sheila and Dave

Peter Fritschel asked us if we could get a sense of which channels were compressing well in the frame, as part of the decision making of which channels should go into the science frame. Greg wrote a script which calculates the compression rate on a channel by channel basis. To keep the numbers manageable we limited the channels to those with acquisition rates of 1024 or higher.

Sheila suggested a time where the H1 IFO was in its best state to give our most realistic compression rates. The time chosen was 1am PDT Friday 31st October, GPS time 1098777600.

The results are appended as a text file showing 2918 channels (name, acquisition rate, compression ratio).

Also attached is a histogram plot showing the distribution of the compression rates.

http://earthquake.usgs.gov/earthquakes/eventpage/nn00466248

Evan, Sheila, Nic, Lisa

To answer Peter's questions , we have relocked the DRMI (without arms) on 1f and 3f 
(10W input power, 27 mW on the BBPD photo-detector).

The DRMI was very stable in both cases, here are the good times:

 Nov 5, 6:00 - 6:15 UTC  DRMI locked on 1f, WFS on 

 Nov 5, 6:30 - 6:45 UTC  DRMI locked on 3f, WFS on 

Evan is about to post plots with error signal spectra.

It is probably a good idea to make some plots with ground motion/ISI/optical lever signals to "capture" these good times.

Comparison of ion yields with purge air and pure nitrogen are given in the attached pdf file.

Summary:

HAM2 moved by about -10 to -8 urad in YAW (in SUS coordinates) and some unknown angle in PIT. This was apparently triggered by the maintenance work for HEPI. Even though Hugh had to back off all the changes due to some other problem they have found, and made sure that SEI sensors are brought back to the original readings, ISI never went back to its original angle.

This is not the first time HEPI or ISI apparently moved though SEI sensors told otherwise.

Details:

In the attached, all plots start before the maintenance and end right when HAM2 was brought back to the old SEI sensor readings. Also, at the end of the plot, MC WFS was engaged.

In CH3 and CH4, you can see that the HAM2 ISI OPLEV saw some big change both in PIT and YAW. The numbers, especially YAW, cannot be trusted too much as the beam is almost all in the right half of the quad diode and nobody took time to confirm the calibration/sign, you can still assert that the ISI angle is totally different from where it used to be.

According to PR3 oplev (CH1 and 2) the HAM2 ISI oplev data in that ISI moved -10 urad in YAW. The optic moved by +4 urad in PIT but this doesn't mean that the ISI moved by this amount.

Other optics on HAM2 are without oplev and therefore don't have an independent measure of the angle external to ISI, but you can see small changes in the OSEMs.

In addition, after the MC locked and the WFS brought the alignment to wherever it thought was good, all MC mirrors settled to different OSEM readings than the original. This means that MC mirrors are sitting at different angles relative to the ISI.

Anyway, the AS beam was at a totally wrong location and we were worried that our alignment was completely wrong, because there's apparently a centering servo for IM4 transmission acting on PZT mirror, but in the end twisting PR3 back by +8 urad in YAW and -2urad in PIT seemed to take care of most of the bad things.

I confirmed that these shifts in optics on HAM2 are NOT due to the bias slider or IFO ASC.

Just like yesterday, I now have new controllers developed with the really correct local <--> cartesian matrices ready to try.   It would be nice if I could give some quantifiable change in the controllers to make the arguement that these will actually work but, I can't without lots more time.

See the first attachment to compare the matrices used by the controller development (in the matlab window) with the matrices actually used currently by the platform.  I can't fathom how this all actually holds it together but at the worst it only rings rather than blows up (see the second attachment of the ISO outs.)

Finally--the third attachment is the new controllers I tried this moning.  The last attachment are the controllers I want to try tomorrow morning developed with the correct matrices.  I predict that these will not blow up nor ring...

Alexa, Evan, Sheila, Jeff, Nic, Lisa

The plan for tonight was to try again the CARM offset reduction with the DRMI locked on 3f as it was done  a few nights ago . 

However, sadly, we couldn't really stably lock the arms on green by engaging ALS DIFF (feed-back to the ETMs). 

Nothing was (at least intentionally) changed with respect to the "nominal" configuration which has worked in the past. 

In the process of collecting and analyzing several lock losses, we identified the following list of problems/action items:

 * L2P for ETMY is significantly worse than for ETMX, we should fix this: as soon as the differential feed-back to the ETMs is engaged, the ETMY green light fluctuates consistently with PIT fluctuations as seen by the optical lever. This effect was really bad in the afternoon (30% power fluctuations; it got somehow better later in the evening); 

 * ringing up of the 13 Hz ETMY roll mode (again, see Kiwamu's entry): Nic tried to damp this mode by using optical lever PIT as error signal and pushing on L2 PIT, but that didn't work. We will try tomorrow to use the  LLO strategy  by using ALS DIFF;

 * at least once we lose lock because of a 3Hz oscillation in the ESD drive (we should remeasure the cross over L1/L3).

While trying to debug the ALS, we did some work on the DRMI to investigate the tricky demod phase business (see  Evan's entry). 

Rana, Alexa, Sheila, Peter, Evan

Given last night's strange behavior from REFLAIR_B, we wanted to check the RF powers coming out the BBPD and going into the ISC rack.

With DRMI locked (on 1f, and then on 3f), we used the HP4395A to take an RF spectrum of the "direct" output of the REFLAIR_B diplexer board. This should be the raw RF signal out of REFLAIR_B, with 12 dB of attenuation from a coupler inside the diplexer.

The spectra (adjusted for the 12 dB coupler) are attached.

For 27 MHz, the power into the diplexer is -41 dBm. Using the diplexer schematic (D1300989), this should give -23 dBm at the diplexer's 3x output, which is well below the compression point of the amplifier (ZHL-500HLN+; 1 dB comprsesion occurs at +16 dBm). Similarly, for the 15x output we expect -13 dBm.

The analogous LLO measurement is at LLO#10494.

This is related to Hugh's log 14774. To elaborate a bit on Hugh's log, I made a measurement with Stage 1 Damped only and HPI isolated. The first plot shows the GND_T240_X ,  ST1_T240_X  and HPI L4C (out of loop witness). There was no coherence with ground below 0.1 Hz but there was significant coherence with HPI L4C. This meant that HPI was somehow introducing excess low-frequency motion.

We then did the same measurement on ETMY and saw no such excess motion. The second pdf shows the corresponding measurement. Stage 1_Y was very coherent with ground_Y. Jim mentioned he had modified the HPI controllers on ETMY as described in Hugh's log, so we decided to try the same on ETMX in X and Y.

This has made a significant difference to the low frequency performance of Stage 1 as shown in the third file. Performance below 0.1 Hz is much closer to ground motion now.

See the attached for some manipulated data.

There are now pressure signals coming from the End Station VEAs just before the BSCs fluid distribution manifolds.  So the pressure before the actuators and the pressure just after the actuators (before and after the distribution manifolds.)  See the first attachment--you can see that there is some 6psi pressure drop from the last transducer on the Pump Station Manifold to the Transducer just before the supply distribution manifold at the chamber.  This is a distance of some 80 or 90 feet of 1" tube.

The idea is that the Actuators are meant to operate at a consistent pressure drop and having the sensors in the area of operation and where we have tighter temperature regulation would be a better thing.  While these epics channels can be conditioned (smoothed, averaged,...) the second attachment shows how much noisier these raw signals would be to produce the differential pressure signal for the servo.  I've subtracted the Return Pressure from the Supply to get the Differential; the vertical scales are the same for the two EX signals,and the same for the two EY signals.  All plots are in PSI.

Why are they so much noisier?  Let me see, maybe the 80 or 90 feet of cable?  We do have an at chamber active signal amplifier, don't know the DCC off hand but later.

Anyway, I may be a little reluctant to switch HEPI to these signals.  I don't think any one has complained about HEPI because we are running on the direct supply pressure rather than the differential.