Alexa, Evan, Sheila, Koji, Rana

We have been locking the arms tonight, with DRMI on 3F and trying to transition CARM to sqrt(TRX+TRY).  

So far no success, although we found several setings which were wrong.  

We tried moving the CARM offset (using the COMM VCO) to -200 Hz (green), and adding a small amount of gain, 1/10 of our nominal gain.  Rana saw that this adds a lot of high frequency noise to CARM.  

Sheila, Kiwamu, Rana, Evan, Daniel, Alexa

We had hope to explore the phase-space of DRMI and improve the lock acquistion time; however, we did not get very far. 

We began with DRMI+arms off resonance under the nominal gaurdian configuration. We acquired the lock 5 times, and found the following acquisition times:

At this point we checked the demod phases for the 1f signal, and decided to adjust the REFL45 phase from 137 deg to 142 deg. We also changed the MICH upper trigger to 5.0 from 10.0. and touched up the alignment (this probably ruins the validaty of our test). With this configuration, we repeated the above and found:

* flipped CARM offset at one point. 

Overall this test was pretty inconclusive, but I thought I would post the lock aquisition times. This evening, we have been running with the MICH upper trigger threshold at 5.0 and it takes about 15 min or so to lock again ... 

A few filter changes for the MICH / BS tonight:

1. Moved the Butterfly stop band filter from the M2 COIL filter banks into the M2 LOCK, so that we only have to use 1 filter. I think there's no danger of the  mode getting rung up by the OL loops.
2.  Removed the 300 Hz notch for the BS Violin and replaced it with a 10 Hz wide 80 dB stopband filter. There is no appreciable phase lag at the MICH UGF of 10 Hz. This catches not only the 299,5 Hz BS violin mode (which was ringing up and saturating tonight), but also a couple peaks at 302 and 303 Hz which were dominating the BS DAC range when the DRMI was locked on the 1f signals.
3. The MICH loop phase margin is only ~25 deg, due to the low freq boosts and the elliptic low pass at 40 Hz. I have made a RLP65 to replace the ELP40. This has approximately the same phase lag, but better attenuation around 100 Hz. During the 3f lock the RMS at the DAC was ~33000 counts (out of 131000). This was ~8-10x more than during the 1f locks and mostly comes from the low SNR of the BBPD used to acquire the REFL 3F signals.

My guess from the noise that we hear in the speakers is that the BS coil driver DAC channels has been lightly saturating whenever we reduce the CARM offset. Its pretty close to the rails before we start and the signals are only noisier when we're on the side of the CARM fringe.

The first attachment compares the ELP40 with the RLP65.

The second attachment compares the M2 LOCK signal with 1f lock (PURPLE), 3f lock (BROWN), and 3f lock with the new filter (BLUE). The new filter gives us a 3-4x reduction in the RMS. I think this should give us a more smooth 3f lock and a smoother CARM reduction.

J. Kissel, A. Pele

While Seb suggests that moving the HAM3 blends to the "250mHz" configuration is a good configuration to "solve" the 0.6 [Hz] feature (see LHO aLOG 16100), we argue that it would be better to live with a 0.6 [Hz], digitally-sharp, peak than to increase the X motion by the factor of several. OR we should find a different set of blend filters for RY that *don't* increase the low frequency motion.

I attach 2 supporting documents:
(1) 16196_20150121183131_H1-SEI_QUIET_3C14C7_SPECTRUM-1105747216-86400.png
The performance comparison between all HAM platforms from the Jan 20th summary pages. On this day, HAMs 2, 4, 5,and 6 are in the "nominal" LHO configuration, all using "01_28" blends on all degrees of freedom, with sensor correction ON for all DOFs, GS13s in high-gain mode, with newly improved isolation loops. HAM3 however, was in Seb's suggested configuration -- the same as the other HAMs *except* for the RY blend filter, which has been changed from "01_28" to "250mHz."

(2) 2015-01-21_H1vL1_BlendFilter_Comparison.pdf
A comparison between the H1 "01_28," H1 "250 mHz", and L1 "400" RY blend filters, as well as the H1 "01_28" and L1 "250" X blends. This shows that 
   (a) In RY, 
       (i) the H1 "01_28" and L1 "400" are virtually identical, as expected. To be precise, for some reason, the L1 GS13 filters are 8% higher in gain, but otherwise identical.
       (ii) The H1 "250mHz" blend is actually *lower* in blend frequency than the H1 "01_28" filters. This means the low-frequency roll-off of the GS13 high pass is much slower for the "250mHz" than for the "01_28".
   (b) In X, 
       (i) there is a good bit of difference in the 0.2 - 4 [Hz] region. We suspect this is because the H1 "01_28" filters were copied over from LLO in Oct 2013, before Ryan had made further tweaks to these blend filters to improve performance around the SUS resonances. The performance is most different at 0.75 [Hz], where the displacement sensor low-pass is lower by a factor of 10.
       (ii) it's concerning that the GS13 high-pass -- though 19% different in overall gain -- does *not* differ between the two site's versions of the filter. This must be what Ryan means when he suggests his filters are "almost" complementary.

While all points are interesting with respect to the sociology and history of the SEI commissioning, point (2)(a)(ii) is the key for HAM3. Because the RY GS13 filter rolls off slower and lower for the "250mHz" blends, the differential vertical GS13 noise is reinjected into the RY loop. This excess residual RY motion couples to X via tilt-horizontal coupling, which degrades the low-frequency noise performance in the same frequency region. Bad. We'd discovered this nasty cross-coupling path as far back as The Stone Ages.

We should find/design an RY filter for HAM3 that *increases* the blend frequency from the H1 "01_28" filters, if we intend to run for a while in such an odd configuration. We may try copying over a few other L1 blend filters. This is all still lower priority compared to the *rest* of the to-do list, but Arnaud and I are worried that the excess low-frequency motion in HAM3 alone might be causing problems with cavity motion.

8:51 Kiwamu to IOT2L

9:05 Bubba to EX

9:06 Karen to EY

9:08 Corey to Squeezer Bay working on 3IFO ISC

9:15 Cris to MX

9:37 Corey to EY looking at ALS optics on table

9:38 Andres working on 3IFO storage cleanup in LVEA

9:44 Kiwamu done in LVEA

9:53 Gerardo X beam tube ion pump work

10:11 Kiwamu and Elli to ISCT6

10:11 Corey back from EY

10:24 Karen done at EY

10:27 Bubba done at EX

10:43 Corey back to Squeezer Bay

10:47 Andres out of LVEA

11:02 Jeff and Andres to LVEA for more cleanup

11:10 Rick and Sudarshan to LVEA PSL area

11:20 Jodi to LVEA taking pics

11:22 Jeff and Andres out of LVEA

11:32 Jodi out of LVEA

12:02 Gerardo out of LVEA

12:22 Corey out of Squeezer Bay/LVEA

14:02 Corey back to Squeezer Bay for 20 min.

(Kyle R, Gerardo M)

The new ion pump became railed sometime after decoupling the pump cart yesterday, and remained railed overnight.
This morning after pumping down the annulus system with the pump cart, we determined that the main valve was leaking.
So, to minimize exposure of the annulus system to atmosphere, we decided to add another valve in series with the leaky valve.
After pumping down on the system for about 25 minutes, the Ion pump started operating as it should, and is currently at 1.5 amps.

Just like ETMX earlier, restarted the HEPI guardian at ETMY to restore the same position for all dofs.  No problems again.  Attached is similar plot showing how different the alignment is after the restart.  Again, the HEPI is exactly the same, cause we made it so.  And the ISI, even though it restores no dofs, holds to its previous position to within 1 urad ( worst is RX=Pitch at ETMY,) all other dofs much less.

As a part of the DRMI investigation, we checked the laser power of CO2X and found that the power had dropped by a factor of two or so a week ago. However it turned out that this was due to a calibration filter (FM2 of TCS-ITMX_CO2_LSRPWR_MTR) which had turned off at that time for some reason. We switched it back on and also edited safe.snap accordingly. The attached is a 100days trend of relevant channels. As shown, the input of the monitor channel stayed at a constant value approximately in the past month or so while the output suddenly changed a week ago, indicating that the calibration filter was taken out.

I found a small mistake in the HAM_gain_matching_calculation script.

The Q of the GS13 model was wrong by a factor a few, causing a slight phase delay around the frequencies that matter for the sensor correction ([0.1Hz-0.4Hz]).  The overall amplitude was thus altered.

This has been fixed and committed into the SVN:

/ligo/svncommon/SeiSVN/seismic/HAM-ISI/Common/Misc/HAM_gain_matching_calculation.m

Here's the correct values that we have so far (I though we had done HAM2 as well, but I can't find a good set of data):

We still need to do HAM2&3, plus all the BSCs. Don't forget to put the ISI in high blend mode with sensor correction OFF when you want to calculate the gain.

Using the Guardian manager, brought down the entire ETMX SEI after capturing the current held position for HEPI.  The Guardian code has been changed to restore all 8 dofs on HEPI to reduce or nearly eliminate alignment changes from lock to lock.  Before HEPI only restored the RZ and Pitch at the ETMs.

The Guardian smoothly brought the system down with no trips.  Restarted the Guardian code and then went directly to fully isolated first time.  No problems with the idea then.  I'll step this through all the platforms as commissioners allow.

Of note, none of the DOFs on the BSC-ISI are restored like this (As opposed to the HAM-ISI where all dofs are restored.)  So, I attach a plot showing the before and after of this morning's restart.  The op-levs are shown and the HEPI RZ.  Additionally, all the rotational dofs of the two ETMX ISI stagesare show to reveal at least one lock to lock alignment change on the ISI.  All the SEI channels are in nano units, Oplevs are urads I believe.  The Stage1pitch is worst at 600nrad tilt, all others are much smaller.

• SEI HAM control loop upgrade testing (Hugh, Arnaud)
• SUS HSTS damping loop work (JeffK, Rana)
• PEM microphone work (Richard)
• 3IFO SUS storage complete (JeffB)
• PAC meeting next week
• Safety meeting held in control room after meeting; John showed picture of crushed pickup truck and talked about safe driving
• Work permits
• C&B will be shut down Thurs. due to power outage

250ml of water added to chiller.

As we found that the beam was too big on the IMC refl camera (alog 16166), I inserted a focusing lens (PLCX-25.4-20.6-UV) in front of it in order to obtain a better and wider view. The belows are pictures before and after the lens insertion.

Before

After

Both pictures were taken with the nominal exposure time of 19444 usec. In the second image, the main 00 mode is seen at the lower right. I am not sure whether if the upper part of the image is explainable by spatial higher order modes. It maybe a ghost beam. Note that this ghost-ish structure was visible with a laser card.

Alexa, Evan, Koji, Arnaud, Sheila, Rana

The good news is that ALS is quite stable tonight, staying locked for up to 2 hours.  

• Earlier in the day we struggled for a while to recover alingment after maintence day.  We had difficulty locking DRMI plus the arms, the DRMI ASC didn't work well, with the arms.  We eventually turned off the ALS WFS, locked DRMI without the arms, used the ASC (MICH, SRC1, SRC2, and PRC2), and offloaded.  Since then we have not had much problem with the DRMI alingment.  It seems that actuating on the ITMs with the green WFS may be spoiling our DRMI alingment.  For now the green ASC is off, with the inputs turned off, so that even when the Gaurdian thinks the WFS are on, they are not. 
• We also have turned off the IMC ASC DOF4.  
• DRMI lock acquisition has been slow tonight, sometimes taking about a half hour.  We checked our open loop gains, which were all normal.  We would like to spend some time speeding this up tomorow so we can make progress faster.  
• We noticed that we were mostly adjusting the alingment of ETMX pitch in the positive direction after the arm transmission would drop, Arnaud noticed that the top mass moved by 10 um starting at 11 am this morning, the same time as a small temperature excursion.  
• We have had two trips of ETMX tonight, which were ISI, Hepi and suspension trips (the first was at 5:15:26 UTC Jan 21st, the second at 7:30:15 UTC) Arnaud investigated the second one, and found that there was a large (200 um) impulse sent to HEPI from the tidal feedback right before the trip. The six hour trend of the signal sent to HEPI shows that the tidal system has sent some relatively large impulses to HEPI several times tonight (second screenshot). 

We have been having trouble transitioning to 3F tonight.  We can transition MICH and PRCL fine, but we have seen a lot of noise at 300 Hz when we try to transition SRCL to 3F.  When we try to transition we see noise at 23.5Hz.  

ALS lock loss times: (all Jan 21st UTC) 0:03:02, 0:34:26

ALS lock loss +HEPI, ISI and sus trips: 7:30:15, 5:15:26 

Lockloss and bad misalingment of IMC due to DOF4: 6:35

Math puzzle: What's wrong with this UGF Servo?

its installed for use in the OMC and LSC at the moment, and could be used in the ASC if we find we want to hold the UGFs constant during TCS tuning.