When attempting to Isolate the ISI, the CPS would trip (now that I think about it, this is weird, I would think it would have been the Actuators,) as the horizontal loops were turning on.  During this time, the ISI has just restored the locations for the Vertical DOFs.  Jim reminds me that the stuff added to the HAM6 Optical Table tilted the vertical CPSs nearly out of spec.

We reset the CPS Targets to the Free Hanging Positions so the ISI wasn't driving anywhere.  It worked first time there.

Our theory is that when the vertical loops are closed and the old Targets are loaded for servoing, the horizontal GS13s are tilted sending a large signal into the CPS via the Damping loops and possibly the just starting horizontal isolation loops.

Resetting the CPS Targets Locations shifted the Pitch of the ISI ~70000nrads.  Dan & Koji say this is nothing to worry about.  I'll leave the SDF diffs alone for now as an easy reference to change the alignment.  If you want to return to the previous alignment, just type the Burt Target value into the Requested Setpoint Field (e.g. H1:ISI-HAM6_CPS_X_SETPOINT_NOW) on the CART_BIAS medm.  Increasing the Ramp Time to something more than the current 5 seconds might be prudent.

I've attached an image that may help.

More work today on SUS SDF weeding.  What I changed:

OM1, OM2, OM3 - Y DAMP gain and OSEMINF gains/offsets updated in safe.snap due to recent tuning. (For Dan, fixed OM2 M1 UL gain which Dan set to 0.136 in error when it should have been 1.363.)

SDF ignore PR M1/M3 LOCK and TEST switches that are now under GRD control.

Finished setting SDF to ignore PR & SR M3 BIO state and associated M3 coil SW1S now under GRD control.

SDF ignore TMS LOCK and TEST switches that are now under GRD control.

HAM6 being pumped by both turbo and ion pump for now

Preliminaries suggest some IPS could use some centering.  Currently unable to drive 0.7mm without maxing ADC (IPS side.)  More after tests complete.

I could not connect to nds1 this morning so I contacted Dave Barker.  He tried to log in but machine was locked up.  I looked at it with the attached terminal and no obvious reason for the machine to be non responsive, but it was.  I reset the machine and everything is back. The reboot took a little longer as a check disk was done automatically because it had been 238 days since the last one.

Current pump down much different that previous pump down of same volume (HAM6) -> Apparent gas load resulting in current HAM6 pump down curve can't be attributed to LVP Krytox grease added this last chamber entry -> Annulus volume in 10-6 torr range -> Adjacent blanked-off vent/purge and roughing pump port dead volumes were valved out after rough vacuum achieved and should still be at rough vacuum -> Need to leak test HAM6 particularly view ports and Turbo pump ballast port

SEI
Unlocking HAM6 HEPI
Clean up of blend filter work from yesterday

SUS
Checks on coil driver readbacks

VAC
Pumpdown curve for HAM6 is unexpected
Opening of GV5 and GV7 is contingent upon resolution of issues with installation of beam dump on top of HAM2

FAC
Stand to anchor in DCS building
Holes to drill for stand in LVEA
Landscaping removing trees tomorrow

CDS
Filiberto working on CPS timing

PCAL
Calibration work at end X

Evan and Rick reported that the Test1 and Test2 On/Off switches were always on, no matter
what the MEDM switch setting was.

The corresponding output of the AI filter checked out okay at the end of the lilac coloured
cables, for both Test1 and Test2.

The output was checked at the end of the DB37 cable going into the TTFSS.  Although a change
in voltage was observed when both switches were toggled, the change for Test2 was not high enough
to trigger the MAX333 switch inside the TTFSS.  This was traced to a problem with the HCPL2231
optocoupler on the TTFSS fieldbox (D1100367).

Since we do not currently have any HCPL2231s, part N1 and N2 were swapped since part B of N2
was not used.  This has fixed the problem for now.



Jeff B, Evan, Peter

Two tip-tilts have been assembled for 40m.  They are sitting on the optics bench in the Optics lab.

These have thinner wire (43 microns in diameter) to avoid the hysterises seen in the thicker 125 micron wire.  Therefore these have to be handled more carefully.  The wires are quite unforgiving of any kinks or handling errors.

As agreed, these do not contain BOSEMs.  Type-B (one stage before the production line)  bosems will eventually be used in these.

The tip-tilts are ready for shipment to 40m.  They have been wrapped in Al-foil.  For long term storage, these have to be stored in a dry atmosphere to avoid rusting of the "piano wire" fibers.  The mirror holders are locked into place for shipment using the eddy current dampers on either side of the mirror mounts. 

The Sl nos are 007 and 038 (Bottom Plate).  Images of the assembled tip-tilts and their various reference numbers are attached. 

We wanted to install the proper parking beam dump on HAM2 before we go high power, and the arm gate valves are closed right now so it seemed like a perfect opportunity. We tried, and failed.

1. Assy in question

https://dcc.ligo.org/LIGO-d1201430

It doesn't show the viewport, so it's not clear how it is supposed to be mounted, except that three hooks grab the outer edge of the flange.

2. The problem

The beam comes out of HAM2 at a steep angle (this picture was taken when we installed the non-final version back in Jan. 2014).

The new beam dump assy seems to be mounted on top of the viewport protector assy. The problem is that the protector is too high, which is kind of obvious from the above picture. For the non-final version, we had to cut the protector ring so the beam comes out of the ring, and a beam dump outside received the beam. We cannot do that with the final beam dump, and as far as the dump sits on top of the protector assy, the beam will hit the protector assy.

As of now, there is a large space between the bottom of the lexan plate and the viewport. There seems to be two versions of the protector assy, one higher than the other, and we're using the higher version. However, even if we use the lower version, it seems likely to me that the beam still does not come to the steering mirror inside the beam dump assy. It should be possible to modify the viewport protector assy such that the lexan plate sits almost flush to the viewport while the beam dump optic table sits almost fluch to the top of the lexan plate. It seems as if this works, but I'm not 100% sure without CAD.

Or maybe it is designed to be used without viewport protector assy. I couldn't find drawing that shows how it's mounted, so I'm asking around.

I told Kyle to hold off to open the gate valve in a hope that somebody offers me an easy solution by tomorrow morning.

I found damped TFs which Kissel took last Dec when he imported the LLO HLTS filters and applied them to the LHO HLTSes 15730.  Today, I ran the undamped set.  Attached are results and comparisons with other HLTSes.  I think this closes the PR3 acceptance measurement dedt.

Rick, Evan

Summary

This evening we went into the PSL and examined OLTF of the FSS.

Since we want to increase the FSS gain, but cannot turn the common gain slider up any further, we looked for other ways to squeeze more gain out of the loop.

Rick had the idea to try to increase the error signal slope by adjusting the demod phase using the delay line. Indeed, we were able to increase the loop gain uniformly by 3 dB. The phase remained more or less unchanged below 700 kHz.

We now have a UGF of about 350 kHz with 50° of phase. The gain margin is about 3 dB.

Details

Delay line switch positions (up/down) are as follows:

So the phase change at 21.5 MHz is 56°. That seems like quite a lot, so perhaps we should take a closer look at the error signal with the FSS unlocked to make sure it's reasonable.

Also, on the manual FSS MEDM screen, we found that the TEST2 enable/disable button didn't really work; we seemed to get a sensible transfer function no matter what.

Attached are the Phase 3b damped and undamped TFs of SR3 taken over the last few months.

The damped TFs of M1 are pretty squashed, but this is because there is some pretty heavy damping filtering engaged for commissioning.

Attached are the Phase 3b damped and undamped TFs of SRM taken over the last few months.

Pcal lines running at 534.7 Hz (Xarm) and 540.7 Hz (Yarm) have been switched with one-another to cross check the calibration between the two arms. Now, the Xarm has a line at 540.7 Hz and Yarm as a line at 534.7 Hz. These will be switched back to its original position once we have a IFO locked data.This study is the continuation of what we reporrted in LHO alog 17582.