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

Using Lisa's updated H1 optical parameters from LHO:13815, and also the as-built positions of the HAM6 optics, I've made some beam propagation calculations for the AS WFS and the beams on ISCT6.  The script and the parameters file are attached.  Here are some things to note:

• The mode matching into the OMC is 87% for a single-bounce from ITMX and 94% for ITMY.  This is in agreement with Lisa's calculations, and as she pointed out there is a lot of sensitivity to changes in the SR2-SR3 path and the mirror ROCs.  These numbers are still just a model, but if we want to measure the true beam that will be hard because...
• The beams coming out of the vacuum (ASAIR and OMC-REFL) are both diverging somewhat quickly, the Rayleigh range for each is about 1.2 meters, and the waist (~0.63mm) is in the vacuum shortly after the beam is transmitted through OM1 (for ASAIR) or reflected off the OMC (for OMCR).  As a result, any propagation calculations that use beam profile measurements on ISCT6 will be very sensitive to the distance from ISCT6 to the in-vacuum optics.  I think errors of a few centimeters between, for example, ISCT6 and OM1 on the ASAIR path will skew any propagation calculations, and errors of this size are hard to avoid.  If people have any ideas for making beam profile measurements on ISCT6 please let me know, at the moment I'm not confident that any measurements of this kind are worthwhile...  (When Chris M. measured the beam at L1, he took a few data points inside the chamber, on the other side of the waist in the beam from the SRM -- see LLO:8182.  Without data points that include the other side of a waist it is very unlikely that a fit to the profile will give a reliable estimate of the beam parameters.)
• The waist in the AS WFS telescope (in-vacuum) is very close to AS WFS B, for single-bounce beams from ITMX and ITMY.  The spot size on WFSB is about half the radius of the spot on WFSA.  This agrees with what Koji observed in the chamber.
• The Guoy phase of the OMs is a little different than what we expected using the nominal beam in T1200410, we need to think about how this affects the control topology for the OMC and AS WFS centering.

Here's some data:

I attach plots of the ITMY single-bounce beam path for the OMC and for the AS WFS.  The locations of the in-vacuum components were calculated using the closeout photos that Koji took before we closed the chamber; they are here and here.  The path lengths between optical elements are probably subject to errors of order a centimeter.

Last night we roughly adjusted the cross overs of SRM and PRM to be about 4.5 Hz, I have checked both cross overs using PRX and SRY.  I adjusted the gain in FM1 of M2 lock for both suspensions, so it is still true that the gain you enter for M2 will be the cross over frequency.

Taking RGA data as the pressure in the X2 Beam Tube module increases following the closing of GV15 (removal of hydrogen pump) -> Expect increasing pressure values indicated by PT345B, PT346B, PT523B and PT524B during test period (testing done on Monday) -> Pressures indicated by these gauges aren't to exceed 5 x 10-7 torr during test period

08:22  Andres to LVEA West Bay cleanroom to collect parts

09:35  Cris to EX

12:00  Gerardo to LVEA taking photos of X-arm beam tube

13:20  Aaron pulling cables from PSL to electronics room

14:41  Gerardo to EX on tool hunt

A DB9 cable was pulled for the outer loop power stabilisation.  The cable is labelled as ISS AA: 13-16.  Male end in the LVEA, female end in the CDS High Bay.

Aaron, Manny, Peter

We ran a set of TFs on this al-metal QUAD assembly today.  The main chain looks to be free of mechanical grounding and suspension resonances look to be roughly in the corect places.  The reaction chain looks to be a little more wild, so we'll investigate that chain further.

Following what I did on BS (https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=13988), I configured the ITMX-ISI and ITMY-ISI in the same configuration:

ST1: TSheila everywhere, except on Z (T750mHz). A T750mHz blend helps limiting the pick up in RZ.

ST2: T750mHz everywhere. Provides isolation above 1Hz without reinjecting noise at low frequency.

On ITMY, we see some good improvement in YAW without degrading PITCH too much.

On ITMX, the degradation in PITCH is a little worse: we might want to turn on some optical lever damping loops to kill this 0.55Hz peak.

DetCharacters have requested to see plots of our loop designs for some of our platforms. I just finished new controllers for ITMX, but they are not currently installed. These are not necessarily representative, but unless smarter people (who are legion) point out where I went wrong, they are what I would like to have working everywhere.

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.

model restarts logged for Wed 17/Sep/2014
2014_09_17 13:14 h1suspr2
2014_09_17 13:14 h1sussr2
2014_09_17 14:47 h1fw0
2014_09_17 18:14 h1sussrm
2014_09_17 22:27 h1fw1

unexpected restarts of h1fw[0,1]. Sus TACQ model changes.

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.

Sheila, Rana, Kiwamu, Alexa, Daniel

We had not been able to lock the PRMI all of today. During the day's usual ISI shaking we noticed that the AS beam had gone nearly of the camera and so spent awhile chasing trends, etc.

After not finding the cause of that, we noticed that the AS45 and REFL45 signals had dropped off to nothing around 3AM local time. As far as we can tell, no one was on site at the time.

Afer some hunting, we found a particularly horrible electronics setup for the 45 MHz modulation amplifier in the H1 CDS electronics room on the same rack as the 9 MHz Marconi generator:

There was an unsecured ZHL-1A amplifier on top of the rack, powered by a DC bench supply (of the lowest quality available), and connected by damaged Banana cables. The banana power cables are intermittent and turn off the amplifier power once in awhile. We could see the power supply current vary to any value between 0 and 400 mA as we brushed the cables - I wouldn't trust this amplifier any more.

Several people disavowed any knowledge of this setup (even after we found https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=11986). It contained a few low quality L-Com cables and several cheap BNC barrels. We must never use BNC connections and these kinds of unreliable adapters in our low noise RF setups. Only N and SMA connections are allowed.

We have relocked the PRMI after removing this setup. The modulation voltage for 45 MHz is now 4x lower. It would be best to make a higher quality RF amplifier setup underneath the PSL table as was done at LLO. We'll be using this weaker modulation for another few days, but we want the higher modulation depth by mid next week, when we get back to the 3f locking.

Yesterday by the end of the day the main path through to the pericope had been aligned on the X-arm table.  This morning we started with a projection as described in https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=13975.  As part of this we realigned the beam through the mask to optimize the shape on the screen.

Later today we aligned the power meter, and ISS photodiodes.  The QPDs were checked and are stlil aligned.  We calibrated the photodiodes and then started to calibrate the rotation stage for the output power to the CP.  However we found a maximum throughput of only 2.5W.  Clearly  we are losing a lot of power somewhere.

The table has a second IR camera located on the optical table.  Before the adjustment during the projection the beam on this looked quite uniform.  After finding that we were losing power I looked at the image on this camera, which is taken using a 50% splitter mirror from the beam going to the CP.  The image is attached, but appears to show that we are now not well aligned through the mask.  We'll need to redo this alignment, but it is surprising that the image from the projection and the image on the table look so different.  Possibly this is just the lower resolution of the camera used to image the projected beam.

The commissioners have been complaining about too much motion in Yaw on the BS (almost 2microns peak to peak at 10 mHz (!!)).

We know we have some pick up between Z and RZ (see the various SEI logs from the last 6 months), so I switched from a ~100mHz blend in Z to a 750mHz. Relaxing the actuation in Z reduced the pick up seen in RZ.

I was afraid to degrade pitch with this change, but we improved yaw by a factor of ~5 without changing the pitch integrated RMS (it introduced a peak around 1Hz though).

I've tried to implement a 250mHz blend, but no improvement...

Thus, the configuration that seems to satisfy the commissioners is:

- Tbetter: X, Y, RX, RY

-Tcrappy: RZ

- T750: Z

I'll check what is the status of this "pick up" on the other chambers ASAP.

Alastair, Greg, Patrick

Alastair tried to use the TCSX rotation stage to change the power this morning. Nothing on the medm screen seemed to indicate that anything was happening.

When I request a search for home, the 'Actual Cmd Position', 'Actual Velocity' and 'Drive Time (ms)' change on the 'Rotation Stage Readback' medm, but the 'Counter Actual Angle' does not.