Rana, Alexa

We repeated a similar procedure as to alog 14022 but this time for L2P. At low frequency, i.e. 0.01Hz we found the optimal gain to be 0.0106.  As Stefan mentioned in his alog, the L2P coupling seems to fall off faster than 1/f^4 at high frequnecies (ie about 3Hz). Therefore at high frequencies we want our filter to be essentially zero. The attached screen shot shows the original filter (FM1 red trace) and two new filters (FM2 blue trace, FM3 green trace). FM2 has a gain at low frequency to match our measurement. The phase is flipped so that the gain in the filter module can remain -1. Then the filter falls off as 1/f^2. FM3 is intended to provide the user an option to include a notch at the resonance at 0.7Hz as seen in Stefan's L2P TF. The other two resonances at 1.1Hz and 0.5Hz seem to cancel with the P2P TF, so we did not include these.

As a reference, the FM2 filter: zpk([],[0.766044+i*0.642788;0.766044-i*0.642788],-0.0106,"n") and FM3 filter: notch(0.749,10,30)

See the first plot for the HAM6 HEPI sensors spectra collected today; this is with the ISI Damped and the HEPI unstopped and I believe the position loops closed.  With the L4Cs looking pretty good, it doesn't look like an interference issue.  The character of the V2 IPS suggests it has a problem,... although it does show some character around 25hz like the other sensors.  Plotted with HAM4 from April for reference.  There is no earlier HAM4 Spectra in the files.  Could it be something with the control loops?

The second attachment compares the HAM6 Spectra 24 hours ago before I unlocked HEPI.  Maybe I screwed up some cabling this morning.  I checked the local basis IPS and they didn't shift enough to go out of range but I should check that physically.

Recall I have not run new TFs on this platform.  There are TFs for HAM6 from October 2013, these look very good and very similar below 10hz to say HAM4--see comparason attachment #3.

Don't understand the foton file generic loops.  Jim and I looked at the Isolation fotons for HAM6 5 & 4. The boosts are the same but the controller filters are not.  HAMs 4 & 5 are near identical for all dofs.  At HAM6 the phases and shapes are all the same but very different in magnitude for every dof. Here is the ratio

Probably no surprise the boost for X will work but the loop goes unstable with all other dofs.

Loops are closed but with no boosts.  I haven't started guardian for HAM6, maybe it exists. I'll try when I won't interfere.

Dan, Koji (from a distance), Rana

We used an OMC mode scan to measure the modulation depth of the 9 and 45MHz sidebands, to close the loop on the recent changes to the amplification path before the EOM.  Koji had done this previously, and measured Gamma1 (9MHz) = 0.198, Gamma2 (45MHz) = 0.305.

Today, we measured Gamma1 = 0.208, Gamma2 = 0.240 +/- 0.01.  The error in Gamma2 is due to an asymmetry between the upper and lower sidebands; using the ratio of the 45MHz USB to the carrier returns Gamma2 = 0.251, while the LSB returns 0.233.  This 10% discrepancy between the 45MHz LSB and USB is consistent across several sweeps of the cavity.  The analysis code used today was thrown together a little quickly and doesn't do a sophisticated job of integrating the curve around the peaks (in fact, doesn't do any integration, just compares the peak heights to the carrier), but when applied to the same data that Koji used earlier this month it finds values similar to his to within a few percent. 

The attached plot has an overlap of five cavity sweeps, with the peaks of the 9 and 45MHz sidebands used in the calculation marked with a cross.  The data are here.  The mode scan was performed off a single bounce from ITMX.  This weekend we'll do a more careful scan for both ITMX and ITMY to calculate (more?) accurate numbers of the mode-matching for each path.

• 9:00:  Lubrication of VEA air supply fans begins (Bubba, Joe D)----->10:30:  not started, need to chat with Richard about fan locations
• 9:30:   Sprague on site to scope out Support Posts for Beamtube with Bubba
• HAM6 HEPI unlocked (Hugh)
• 10:10-10:20:  ITMx oplev check for clearances on pylon, since Jim W found issues (jason)
• 11:16 Karen cleaning at EY
• 1:22:  Photos at Beer Garden & Quad testing at Test Stand (Betsy & Travis)
• Lost fan for the corner station (affects Lab area and Control Room); will get fixed Monday
• projector1 online in the Control Room (Cyrus)
• Charging work complete (Gerardo, Mike)

HVAC Fan for Control Room/Lab area is OFF, please power off equipment which can heat up the area!!

Richard called and informed me that a circuit breaker has failed while Bubba was restarting supply fan 5 in AHU3. We cannot repair this today so those in the control room may be a little warm this weekend. There is still air flow, perhaps 1/2 of normal and currently the control room seems to be the most affected. 

The attached plot shows 4 rooms in the area and clearly the control room is the worst.

I would suggest turning off as much equipment and lighting as possible for the weekend. You may prop open the exterior doors (near the control room) which may help. Please do not let coyotes into the building.

PS. The projectors are likely big heat sources. 

I've installed another Mac Mini to drive the left hand side projector in the control room.  It is accessible as projector1, in the same way as projector0 which is running the seismic DMT plots - that is to say, using Screen Sharing.  Note, if you want to run DMT on this machine, you will need to talk to Jim/Dave to get it set up - any of the other tools should work as expected.

With the looming weekend I bit off a mouthfull this morning when I suggested I unlock the HEPI.

I did so but while doing that I noticed much of the Actuator ranges were very consumed--talk to me if you want more info.  Range of motion tests failed on several Dofs but only because the offsets were so large that the test criteria was satisfied at the start--obviously I need to work on the test script.

Back in October 2013, TFs were run and controllers developed--I don't know who at this point.  Regardless, these loops are too aggressive and the Boosts ring up.  I've got the controllers on manually now without the boosts controlling to the cartesian position before I unlocked the platform.  However, some of the loops aren't quite getting to the Set Point.  I don't know if it is the controller without the boost or if it is interference with something in the platform.  Given that I see the Postion approaching the Set Point but not quite getting there has me leaning toward the interference issue.

To do:

* I should install the Generic 2hz loops already on HAMs 4 & 5 and see if the loops can be turned on with the boosts and if the error point will go to zero.

* Run more range of motion/linearity tests to assess interference more thoroughly.

* Collect Spectra to confirm intereference

* If motion range can be confirmed, collect Transfer Functions; if interference is a problem, see below.

* Redo filters with good TFs and get under control.

**** Do more with HAM6 ISI, currently only damping!

Interference problem solutions:

1)--May be able to remove Bellows shields and modify to give more room--not easy but not too bad.  It seems to me that building the Actuator with lots of welding distorts things enough that the ideal Actuator floating/relaxed/center position isn't always the center position.

2)--Disconnect Actuator from Foot and rezero.  May be the better solution but will take a day at least.  We are pretty good at connecting the Actuators without shifting the platform too much but that is the main risk--Disconnecting the actuator and rezeroing will lose the reference IPS position.

The daqd executable on x1fw1 has been changed from daqd-trunk-r3626 to daqd-r3827 to test changes to trend.cc to properly record integer trend files.

Rana, Alexa

Since we saw a lot of YAW motion from the BS last night, we decided to look at the L2Y coupling again. The  original filter FM1 installed in the drive align was created via alog9394.

We injected a sinusiodal excitation in BS-M2_LOCK_L and examined the M3 oplevs. First we excited at 0.01Hz, and measured peak-to-peaks via StripTool at several gains. Assuming a linear relationship, we then determined the best coupling gain to be 0.0025 (at 0.01Hz). Then we excited at 4.57Hz, and found the mag, phase at two gains. This allowed us to determine the coupling gain to be 0.002203 (at 4.57Hz). We then created a filter accordingly to match the respective gain couplings at low and high frequency. The filter is installed in FM2 (see first attached image). The gain in the filter bank should be set to -1 for either FM1 or FM2.  The second image shows both FM1 (blue) and FM2 (red).

For refernce FM2: zpk([0.694211+i*0.827328;0.694211-i*0.827328],[0.642788+i*0.766044;0.642788-i*0.766044],-0.0025,"n")

(Borja)

please find attached a short document on how to identify which ESD quadrant we are driving from the slope of the 'oplev deflection vs VBIAS' plots we obtain during the ESD charge measurements. We know that the quadrant labelling on the Epics channels and MEDM windows do not correspond with the actual ESD quadrants being driven and the discrepancy is different between ETMX and ETMY.

ALIGO Install

• Next downtime opportunity on Tues: 
  • HAM5:  open viewport cover for oplev (Jason)
  • PSL work:  restart front end, refcav will lose lock (Peter K)
• HAM6 HEPI unlock this morning (Hugh)

Commissioning

• drmi locking accomplishments from last night discussed
• 3F filter work will go on today/this weekend
• ready to open arms mid next week

3ifo

• SUS running TFs at test stand
• discussion about 3ifo/iLIGO HEPI storage

no restarts reported

Kiwamu, Sheila, Rana

We started by locking PRMI and taking a long spectrum of the BS op Levs, it seems that Alexa's new length 2 yaw filter (alog 14022) has reduced the yaw at around 0.05 Hz by a factor of about 2 compared to alog 13997.  The first screenshot attached is a spectrum of the BS oplev with PRMI locked.

We then moved on the DRMI locking.  After debugging the guardian a little bit, we were able to catch lock infrequently.  Out first lock ended at Sept 19 4:55:19 UTC, and was about 10 minutes long.  It locked again at 5:05:36 UTC, at 5:24 UTC we left everything alone to get a clean stretch of data until 5:42:40 UTC.  At 5:33 UTC there were a few mode hopping glitches. In general the mode hopping events are not as frequenct tonight as last night, and they are reduced when we have better alignments.  The attached video is from a DRMI lock. 

We measured the loop gains.  We found that with the gain settings used last night (alog 1402 ) gave us a prcl ugf of 130 Hz, and a MICH ugf well below 10 Hz.  We now are using a PRCL gain of 6.4 (to get a UGF around 80 Hz) and a MICH gain of -50 (ugf of 10 Hz).  Measurements attached.

Kiwamu also noticed that SR3 pitch motion at 0.8 Hz was large, kiwamu implemented a SR3 oplev damping loop with an upper UGF a few Hz and a lower ugf of 0.3Hz is, copied from the PR3 oplev damping servo. 

PRMI is now locked. 

I am summarizing here recent progress on SEI units, and providing guidelines regarding what needs to be done next week.

BSC-ISI Nominal Configuration

A lot of different configurations have been tried in the past 10 days.

Two main conclusions:

- We don't want to put low blends on Stage 2 to avoid low frequency noise reinjection ( see logs here and here)

- We have a lot of pick up between Z and RZ. Relaxing the Z actuation (higher blend) helps in Yaw (see logs here and here)

The best BSC-ISI configuration so far is:

Stage 1

- X, Y, RX, RY, RZ: TSheila blend

- Z: T750mHz blend

Stage 2

- T750mHz blends on all degrees of freedom

HAM-ISI Sensor Correction

We've successfully implemented some sensor correction on HAM2-ISI in X (see log here).

It helps the absolute motion by a factor of ~4 in Yaw, but we have to check what the motion of the cavity looks like (see the to-do list below)

Scripts Improvement

A bunch of improvements have been made on the commissioning scripts (see log here). Jim is finishing up the work started on Routine_6 and should commit that pretty soon.

We also created some simple scripts to make the commissioning/debugging process faster (see log here).

TO DO LIST

BSC-ISI Sensor Correction

By doing some comparison with the LLO configuration (see log here), it seems that the next big step would be to implement sensor correction on the BSC-ISIs. It would help us winning a factor of a few around 0.5Hz.

We already started to look into that and we should have some exciting results soon.

Cavity Motion Study/Common Control

Even if we had some promising results with sensor correction on HAM2, we need to check the motion in the cavity: reducing the optical lever motion (absolute motion) doesn't mean that the cavity is quieter.

One of the idea will be to implement sensor correction using the SAME ground instrument for HAM2 and HAM3. It will be interesting to see what the cavity is doing when both of the chambers are control by the same input signal.

We need to:

- Implement sensor correction on HAM3

- Compare PRCL when the sensor correction is on and off on both chambers

There was some suspicion that the REFL beam is somehow clipped on LSC REFL_A diode. Yesterday I made a long scan of RM1 and RM2, separately and at the same time.

LSC-REFL_A_LF is good, ASC-REFL_B too.

I had to move RM1 and/or RM2 by a large amount to make the LSC-REFL_A_LF drop.

ASC-REFL_B is also good, though the safe range is smaller than LSC (not surprising considering the short focal length lens in front of LSC diode).

ASC_REFL_A is unhealthy.

Something is wrong with SEG4.

It seems as if SEG4 has a lower trans impedance, in that when I steer the beam to SEG4 (all power falls on that segment) we get 18000 counts, but when I do the same thing to SEG1/2/3 they rail at 32k counts.

In the attached, the beam was in SEG3 at first, and I walked the beam to SEG4, then SEG1, then SEG2, and then back to SEG3 by turning RM1.

The problem seems to be in the WFS head, not in the WFS interface board. Connected the WFS output cable from the REFL_A head to REFL_B input and the problem is still there.

For the moment I adjusted the digital gain of SEG4 such that there's no coupling from PIT and YAW motion to the SUM (new H1:ASC-REFL_A_DC_SEG4_GAIN=1.9), but this needs to be investigated further.

The second attachment shows the REFLA SUM spectrum of before (green) and after (red) of the gain adjustment when I was modulating PIT of RM1 at 3.3Hz and YAW at 5Hz. For comparison, Blue/Brown are the REFLB SUM data which show no alignment coupling.

Could be the electronics in the head or the cable (one end of the differential signal is dead?). I hope that the diode is not damaged.

Though not impossible, I don't think it's clipping because SEG4 never went larger than 19000 counts during RM1/RM2 full scan.

Alexa, Rana, Sheila, Kiwamu,

We locked the DRMI tonight for the first time. It could stay locked for more than 10 minutes.

(A prep: PRMI locking with REFL signals)

Before moving onto the DRMI locking, we wanted to lock the PRMI on the sideband without using the AS detector. We first locked the PRMI with the conventional sensors i.e. REFL9_I for PRCL and ASAIR_45Q for MICH respectively. By exciting and looking at transfer coefficients, we figured out 

REFL45_Q = -12.5 x ASAIR_RF45_Q for MICH readout

So, we put 1/-12.5 = -0.08 in the input matrix and this worked.

Also, the large fluctuation we saw in REFL_A_RF45 yesterday (alog 13968) was visible today as well before we transitioned to REFL_RF45_Q for MICH. We checked if this behavior is also visible in REFLAIR_A_RF45. This was actually visible in REFLAIR_RF45 as well. This incidicates the fluctuation comes from some kind of common place in the REFL path or the ASAIR_A is imposing this fluctuation in the MICH through its feedback. Once we transitioned onto REFL_A, we saw both REFL_A and REFLAIR RF45 signals suppressed. On the other hand, as expected, ASAIR then started wandering.  We should check some clipping or some obvious things on the ASAIR detector tomorrow.

(DRMI lock)

We aligned the SRC by locking SRY with ASAIR_RF45. Also we adjusted the demod phase of ASAIR_B_RF90 such that the signal is maximized in in-phase. At the beginning, we adjusted the demod phase such that the PRMI carrier resonance gave negative values.  This was then flipped by 180 deg after we locked the DRMI because this signal stayed at a negative value when the DRMI was locked.

• REFL_A_RF9_I => PRCL
• REFL_A_RF45_Q => MICH
• REFL_A_RF45_I => SRCL

To lock the DRMI, we reduced the MICH gain by a factor of 5 according to Anamaria's DRMI document, but eventually we ended up with a gain reduction of only a factor of three which resulted in repeatable locking. We did not have to change the PRCL gain from the PRMI locking gains as expected. We guessed the SRCL gain from the same document. We fiddled with the control sign and gain for an hour or so and eventually it started locking.

We coarsely adjusted the PRM and SRM M2 stages to maintain the DRMI lock for a long time. The gains are right now based on some models/guesses. So we will revisit these values tomorrrow.

(SRC hopping ?)

We are not sure what is going on, but the SRC seems to jump back and forth between two modes. It looks as if the hopping is triggered by some slow misalignment. Depending on time, it happened as frequent as once per a couple of seconds. And sometimes it did not happen for some time like 20 seconds or so. This is visible in the dark port camera and AISAIR_RF90 which went back and forth between a high and low values. The low value went to a negative number for some reason. We need to investigate this issue more to figure out what is happening.