Jeremy B, Matt H, Jeff B, Apollo

As you may remember from one of my alogs last night, i forgot to pull the FC on the witness optic in HAM3. It was decided to play it safe and pull the door to get at it. So before anyone else started in chamber work we quickly pulled the door. Particle counts in cleanroom were 10 counts and straight after the door came off was also 10 counts in chamber. Door came off at 9.09 am, Half the ISI was locked....and whilst ISI was being locked I looked at MC2 optic. Looked same as yesterday which is awesome. I tried pulling the FC on the small optic and in doing so it ripped so I only had a little bit come off with first go (I think the layer was to thin). So had to try to get at it with a gloved hand to get the rest. We did so, but it definitely meant that the cautious approach was the right one. We did a quick check to make sure we got all the FC, unlocked the ISI and the door went back on at 9.22am (off for around 13mins). Jeff checked particle counts as the door was jamming shut with the chamber and saw no puff of particulate. 

Stuart has a detailed log of timeline and particle counts that hoping he will add to this

Matt H.  requested that we verify the ISS PDs were still connected in vacuum.  I was able to get to the all 16 cables and tested each pair. They all tested fine with a reading of approximately .384VDC Anode to Cathode and OPEN Cathode to Anode on my Fluke 87V set to diode test. The last set I tested seemed to be reversed so I left them disconnected until I can have better access to the chassis under the chamber behind the HEPI support Structure.

I have reconfigued the Vacuum Alarms To Cell Phones to not alarm on the missing MX Y1 beam tube cold cathode (343B) and replace it with the cold cathode on the other side of the gatevalve (344B). This is a temporary change until 343B gauge is repaired.

WP4750. Shivaraj and Dave.

With Stefan's kind permission, we added the first version of the PCAL front end model to h1odcx as a CAL top-names part. We have not restarted the DAQ, so the data from this model will be corrupted until we do so.

Channels in this new system have names which start with H1:CAL-PCALX_

JeffK HughR

Look pretty good, Jeff looked pretty close.  Maybe I'll get a chance to plot a Dof by Dof for better compare which we did on screen.

Meanwhile see the attached for a Global Basis comparison with data from back in November.  Current data is bottom set (see title); two bands zoomed in 1) main resonances 2) upper frequencies where the ISI cable bracket might show itself.

ITMx has been unlocked for SEI TFs.  ITMy has been locked for ACB install.

Travis and I went into the 3 vertex BSC's this morning, and locked ITMY (for ACB install) and unlocked ITMX. While I was there, I looked around at BSC2 for possible rubbing, and checked ITMY for loose masses but found nothing. Will try running tf's at BSC3 today, but the activities out there might make it a futile attempt.

Attendees: Bubba, Jeremy, Matt, Dugh, Robert, Jeff K, Mike, Hugh, Stuart, Jason, Terry, Jodi, Vern, John, Travis, Guillermo, Mitchell, Arnaud, Aaron, Keita, Jeff B, Jim, Filiberto, Richard, Dale, Gerardo, etc …

Today's Tasks:

•	Work will continue on HAM2/HAM3 today – Matt/Jeremy/Apollo
•	Contamination & Control will be present at HAM2/3 activities– Jeff B
•	Illuminator work at End Y – Aaron
•	Locking/ Unlocking suspensions on BSC1/BSC3 respectively - Travis 
•	Stage Viewport preparation will continue today - Gerardo
•	Mitchell and Mike V will continue with ACB work (Travis will assist)

A set of TFs were previously taken for the SR3 (HLTS) suspension (see LHO aLOG entries 12929 and 12945), to complete Phase 3a power spectra have been taken with damping loops both ON and OFF for all stages. These H1 SR3 power spectra have also been directly compared with equivalent H1 PR3 measurements (allhltss_2014-07-24_Phase3a_H1HLTSs_ALL_Spectra_D*.pdf). The plot key is as follows:-

Black Dashed Line = Expected Sensor Noise
Blue Solid Line = H1SUSPR3 2013−10−07_0800
Green Solid Line = H1SUSSR3 2014−07−24_1030

Summary:

Noise floors for SR3 are consistent with expectations. However, it should be noted that virtually all M1 stage OSEM channels exhibit narrow frequency comb features above ~20 Hz, which are only present in the damped power spectra and could therefore be be re-injected noise from the electronics chain and will need to be further investigated.

All data, scripts and plots have been committed to the sus svn as of this entry.

A clean set of TFs were previously taken for both SR2 & SRM (HSTS) suspensions (see LHO aLOG entry 12950), to complete Phase 3a power spectra have been taken with damping loops both ON and OFF for all stages. These power spectra measurements have also been directly compared (allhstss_2014-07_24_Phase3a_H1HSTSs_ALL_Spectra_D*.pdf). The plot key is as follows:-

Black Dashed Line = Expected Sensor Noise
Blue Solid Line = H1SUSSR2 2014−07−24_0900
Green Solid Line = H1SUSSRM 2014−07−24_1000

Summary:

Noise floors for both SR2 & SRM are consistent with expectations. However, it should be noted that SRM M1 T3 LF and RT channels exhibit a comb of narrow frequency features above ~20 Hz, which since observed in both damped and undamped power spectra could be induced by ground loops.

All data, scripts and plots have been committed to the sus svn as of this entry.

After securing doors on HAM3 (see LHO aLOG entry 12975), TFs have been taken overnight as part of Phase 3a testing to check for rubbing or other issues that may have developed as follows:-  

- PR2 M1-M1 undamped (2014-07-24_1090302332_H1SUSPR2_M1_damp_OFF_ALL_TFs.pdf) 
- MC2 M1-M1 undamped (2014-07-24_1090284714_H1SUSMC2_M1_damp_OFF_ALL_TFs.pdf)

HAM3 ISI Status: ISI unlocked, no damping or isolation loops running.

PR2 & MC2 alignment: No offset was applied during this measurement.

The undamped measurements from above have been compared with other H1 HSTS suspensions at Phase 3a of testing as well as the model (allhstss_2014-07-25_Phase3a_H1HSTSs_M1_Doff_ALL_ZOOMED_TFs.pdf).

Summary: 

Both PR2 & MC2 M1-M1 TFs show good agreement with the model and perform consistently with other HSTS suspensions, thus raising no concerns.

All data, scripts and plots have been committed to the sus svn as of this entry.

The licenses for Matlab are now being served by a local CDS license server, which should reduce the vulnerability of network interruptions to Caltech in obtaining Matlab licenses.  This applies to new matlab sessions started from newly opened shells, existing open Matlab sessions should be unaffected.  Also this only applies to Ubuntu workstations at this time.

The only change you may see is warning messages on startup referencing non-existing directories in the matlab toolbox path.  We have licenses for more packages than are installed, which causes the warnings.  This will not affect your ability to use Matlab.  

Undamped transfer functions will start on opsws1 and opsws10 when HAM2 ISI measurements will be done

Matlab TFs are set to run on HAM3 suspensions overnight as follows:-  

- MC2 (HSTS) M1-M1 undamped TFs, Starting at ~6:00pm July 24th (local)
- PR2 (HSTS) M1-M1 undamped TFs, Starting at ~11:00pm July 24th (local)

When complete at ~3:00am July 25th (local), the measurement status will revert to OFF and damping loops will be restored to the ON state.

These measurements have been initiated from the opsws2 workstation.

08:45 Matt H. and Jeremy going into HAM2
08:50 Mike V. going into LVEA to help Mitchell with CPB
09:12 Stewart going into HAM3
09:18 Filiberto swapping ITMY and ITMX UIM coil drivers [WP 4748]
09:20 Hugh going to BSC1
09:38 Nathan starting unattended work with laser in OSB optics lab
10:12 Filiberto finished WP 4748
10:19 Mike L. going to LVEA west bay to work with Gerardo on optic charging experiment
10:47 Mitchell and Mike V. going to LVEA west bay to move CPB
10:54 Gerardo going to LVEA west bay to work on optic charging experiment
11:06 Hugh and Jim out of BSC1
11:44 Mitchell and Mike V. out of LVEA
12:51 doors going on HAM3
12:55 Jeff B. and Andres going to HAM3
12:59 Stewart going to HAM3
13:03 Richard going to end Y to take pictures through viewports
13:22 end X transitioning to laser hazard
13:43 Mike L. and Gerardo going to west bay to work on optic charging experiment
14:24 Richard back from end Y
14:45 Manny to end Y to turn off illuminator
15:15 Jim B., Patrick replacing light bulb in right side projector
15:16 Paul and Jordan to end Y to pull cable for accelerometer
15:18 Kyle starting WP 4749, PT343 valved out from beam tube volume
15:33 end X transitioned to laser safe
16:02 Mike L. and Gerardo out of LVEA
16:30 Gerardo and John W. discovered that the right side projector is overheating, taken down
16:45 Nathan will be supervised by Dick G. in the OSB optics lab

Closed 10" gate valve at X1-9 port on X1 beam tube -> PT343A,B now unpumped and no longer measuring beam tube pressure -> Ignore PT343B until further notice -> Replaced 1.5" O-ring valve at X1-9 with portable RGA assembly -> Will leave 10" valve closed for the next several days while I bake the RGA -> Following RGA bake-out, GV14 will be closed and the 10" valve opened for a few days so as to acquire pressure accumulation data on the X1 beam tube module 

(Matt H, Stuart A, Jeff K, Jeremy B)

After getting the okay from SEI, I unlocked the 4 HXTS's on HAM2. TF's were run on All 8 suspensions (4x HXTS, 4x HAM AUX) on the table and all were given the all clear. So SEI TFs should be good to start..once we damp the suspensions of course :-)

We took particle counts. Cant remember exact number but Stuart has the numbers and i believe will post

Jeff B, Andreas, Jeff K, Stuart A, Jeremy B, Matt H, Apollo).

Both doors on HAM3. Jeff B started by inserting optic Started on PR2 side as that is the "least" important of the two optics in tha chamber. There was a drop of FC under the optic (not from a run down the optic, obviously fell off during painting) so that was cleaned up easily. Once particle counts deemed good to go, first contact was peeled (there was a little bit of the outer crust left behind from say 2-3 o'clock position and 4-5 o'clock position.....I decided not to attack it with a swab and just leave it...Calu you need to practice your first contact outer layer painting skills :-) :-D). Its only a bit and well out of the beam path. Optic was unlocked and TF's taken. Once given the all clear door went on. Stuart has a log of particle countsduring process, timeline and also how many particles I deemed I saw on optic throughout the process.

Once HAM3 east door on, we checked particle counts on west side. These were low and so went to peel FC here. Found that top gun nitrogen tank low, so swapped out before blowing to peel FC. Once swapped, peeled FC, again unlocked suspension and then did TF's. Once these past door went back on. They had some troubles getting a good angle to put door on so took a little longer than wanted. Again Stuart has log of timeline, particle counts, particulates on optic, etc.

I talked to Travis about mobility wafer and if he wanted it replaced (by replace I mean swap out the the wafer already in it....it was put back in its original position before the ISI guys balanced the table by Travis and I) before we closed up. He suggested to leave it as looking for a delta if anything moves from time of closing/pumping down...so I left it as is.

Damn...I know one thing I forgot.....to peel the FC on the small optic...how did I forget that #facepalm.......hmm  I wonder if I took off a viewport I can reach in and get it. Its on the outer leg of the MC2 suspension. Will talk to Calum about.  Who has the longest reach at LHO ? We may just be able to get it from the viewport.....To all and sundry....dont let me forget for HAM2............

Summary: in preparation for beam arriving in HAM6 / ISCT6, I wanted to explore the potential for mode mismatch to the OMC, and how it might be corrected.  I found that for essentially any reasonable combination of errors in optic positions and ROCs, the mode matching can be recovered by a small adjustment to SR2.  (Given the way the SRC is designed, I don't think this is surprising to anyone -- it may even be intentional! -- but it was an interesting exercise.)

Details:

At L1 they observe a mode mismatch to the OMC of ~25%, depending on which ITM supplies the bounce.  Lisa found that this could be caused by a small (1.5cm) change to the SR2-SR3 distance, assuming the PRC length is nominal.  At LHO we are a 2-3 weeks away from measuring the beam arriving in HAM6.  In principle, there may be errors in the position of any of the optics on the order of 1cm, and errors to the ROC for the curved mirrors (of order ~few cm?).  The question is, if we are very unlucky and the initial mode matching to the OMC is bad, can we correct it in a simple way?

I used Lisa's script from LLO:8565 as a starting point to estimate the mode mismatch that could occur from small errors in the positions and ROCs for optics in the output path, SR3 to OMC.  At LHO the PRC length has been measured to better than 1mm; it's very close to nominal, so for now I assume the positions of the PRs, the BS, and the ITMs are correct.  That leaves six optical components with un-verified positions: SR3, SR2, SRM, OM1, OM2, and the OMC.  (I fold errors in the position of OM3 into the position of the OMC.)

Modeling a beam subject to small variations in eleven optical parameters is a lot to keep track of in closed-form, so I implemented a Monte Carlo approach: for 10k trials I independently varied the longitudinal position and ROC of the six optics in the output path, and calculated the mode overlap with the OMC waist (w0=490um).

Errors in position were drawn from Gaussian random variables with sigma = 2.0cm; these were applied to SR3, SR2, SRM, OM1, OM2, and the OMC.  Errors in radius of curvature were drawn from a Gaussian distribution with sigma = 5.0cm; these were applied to SR3, SR2, SRM, OM1, and OM2.  I'm not sure if these values are reasonable (2cm in position sounds like a lot), but they seemed like fair conservative guesses, based on the as-built dimensions for L1 in E1200274-v3, compared to the nominal values in T0900043-v11.

For 10k trials, the median overlap with the OMC waist after varying the parameters of the optics was 0.85; the distribution is shown in Fig2.  This median is better than what's observed at L1, which may mean they got unlucky, or the magnitudes of my errors are too small.  (NOTE: for simplicity I am using a single bounce off ITMX with the nominal ROC of 1934m.)

Next, I used a la mode's optimizePath() function to correct the mode mismatch by varying the position of SR2.  Based on table layouts this seemed to be the easiest optic to move.  The range on the optimization of SR2's position was +/-5cm.

The result is that even for very bad mode overlaps, the errors can be compensated by moving SR2.  And, whether or not the overlap can be completely recovered is only a function of how far you can move SR2.  (I.e., if we are terribly unlucky at H1, maybe we can move it by more than 5cm.)  This might be known already to optics experts, but it was surprising to me that even for large errors in optic ROCs the mode can be corrected by changing a single degree of freedom.  I guess this is what you gain when your beam-reducing telescope has a short Rayleigh range?  (Flip side: we're really sensitive to the position of SR2 and SR3.)

In the attached: Fig1 is the distribution of mode overlap to the OMC, for 10k trials with independently varied parameters.  Fig2 is how well you can improve things by moving SR2; the horizontal coordinate is starting (mis)match, and the vertical coordinate is corrected (mis)match, after at most a +/-5cm change to SR2.  Fig3 is a comparison of how much you need to move SR2 vs how much you get back.  The scripts I used are there too.  It's not a very elegant implementation, for 10k trials it takes way too long to finish, something like an hour.



Notes:

 - This is all fine from a mode-matching perspective, but I don't know enough about optical cavities to say whether changing the SRC length by 5cm is okay or a complete disaster.  Also, I think that a la mode's optimization procedure changes only the position of the optic in question, and doesn't take into account the changes to relative lengths.  So, when it moves SR2 by 5cm, a la mode is increasing the distance from SR3 to SR2, and decreasing the distance from SR2 to SRM.  This would be fine if SR2 was a lens, but it's a mirror; if the position changes by 5cm the SR3-SR2 and SR2-SRM distances should change in the same direction.  (I think that since the SR3-SR2 distance is the important one, this is does not change the results, but I haven't checked in detail.)

  - I belatedly realized that the ROCs for the SR optics have been measured and they're listed on the core optics website (galaxy.ligo.caltech.edu/optics).  So, errors in the ROC of 5cm are probably way too generous.  I'm not sure about the OM1 and OM2 optics.

 - Of course in order to correct something you need to measure it first.  If the mode mismatch is bad we'll have to characterize the beam on ISCT6 with Chris M's beam scan technique or something similar.  It might be worth modeling how accurately we can measure the necessary correction to SR2's position.