Attached is the calibrated spectrum with PSL (red). References are all with the old refcav setup. Apparently PSL doesn't look good, but don't take it too seriously (yet).

When I took the data I've turned off the PSL laser room HEPA, PSL ante room HEPA and PSL room A/Cs off, and turned the make up air down to 30% level with an approval of Michael Rodruck.

Power fluctuation in the cavity is ridiculously large (you can see that the beam spot is moving by the beam radius or more on the ETM), which might be due to high wind today. I'll take another shot tomorrow.

Also it might be that the Prometheus temperature is too low. It's not that I'm seeing that Prometheus is misbehaving, but in the past Bram experienced some problem operating it at too low or too high a temperature. I want to unlock the PSL refcav and raise the crystal temperature a bit but I don't think I'm qualified for PSL room.

BTW we tried turning ISS on and it didn't make any difference.

Jim & Hugh

Based on our dial indicators, we had a little more aligning to do left over from Friday.  We did that and then fine tuned the elevation, again with the dial indicators.
Next we opened up the Chamber and shot the position with the Sokkia SetIIX.  The East/West position was right there (y=0), of course the machine only reads out to the millimeter.  The North/South position was due west of monument LV25 with the west end of the Support Table 2" (<0.1mm south) and the east end 14" or <0.2mm north.
So with the position confirmed we checked the level of the Table.  It is 0.1mm low and level to +-0.1mm.  Tomorrow we'll start building the stack, if we have the forklift.

Attached are my notes from this for your perusal.

Went to EY. The power coming out of the fiber was 174 uW.

Originally the Prometheus red crystal temperature was 42.36 degree C. We ended up lowering it down to 31.39 degree C to get a beat note.

The green power dropped by about 20% judging from the QPD sums (e.g. QPDB sum used to be 7500, now it is 6000) and H2:ALS-Y_REFL_B_PWR_INMON (uset to be 12700 unlocked, now it's more like 10200). I changed the offset in REFL_B_PWR accordingly. This means that the old 8000 counts is now 6400 counts.

The waveplate for the fiber output was adjusted to maximize the beat note, which was about -39dbm. Turned on the servo, adjusted the temperature knob several times to relieve the slow temperature servo, and it worked OK.

We measured the OLTF of the PLL even though there's no reason it should change. The UGF was about 23 kHz.

See Jax's entry about the green power going to the chamber and the actual data of the PLL OLTF.

Now the arm locks.

While I am at LLO, I am running the Phase 2a chamberside testing of MC1.  I have read the log and see no reasons why I should not actualte on MC1 chamberside.  I am aware that people are on the floor and even possibly working on the same table.  I'll look at the DQ as I go.  Please email me (or call my cell) if you need to.

The Apollo crew is staging for ICC. Cleanroom sock will be put in place. Christina and Karen got first cleaning in this morning. We will try for second cleaning dome/door removal tomorrow.

Bubba and crew got the cleanroom over HAM3 on Friday afternoon. Christina and Karen got first cleaning in this morning and did second cleaning after lunch. I'll check particle counts prior to door removal.

This weekend I remounted the first calcite polarizer (CWP1) and re-optimized the extinction ratio of the system at low power. 

The beam was initially not centered on the calcite polarizers (off-centered horizontally by ~3-4 mm on each in opposite directions). I released the posts holding the breadboard and rotated the breadboard CCW to center horizontally on both calcites. This misalignment probably happened when the granite block was moved to make room for the beam profile measurements.

I also centered the beam vertically inside the isolator (optics and magnet), but the beam is no longer centered on the two input/output irises, indicating that the breadboard is NOT parallel to the table, but sloped upward. I will check the sloping again on Monday.

At 2.2 mW power, the extinction of the first calcite polarizer was 56.43 dB.

Extinction measurements after CWP2:

This should be checked at higher powers also.

I redefined the HAM-ISI Matlab path and modified the tree of the HAM2 folders to use the commissioning scripts. Then, I installed the symmetrization and the damping filters on HAM2. I will keep installing the blend and the isolation filters next week.

Thursday, few measurements were performed with the cavity locked. This aLOG presents some results.
In order to keep the cavity locked, Isolation filters on the HEPIs were always engaged, HEPI-BSC6 was yawed by ~180micro radian, damping filters on ISIs, TMS, QUADs and the FM were always engaged. The ISC longitudinal error signal was fed back to BSC6-HEPI (UGF ~1mHz). The simplified control schemes of the BSC-ISI and the HEPI are presented in attachment (SEI_Simplified_Control_Scheme.pdf)

The isolation filters of the 2 ISIs are tuned using the following parameters:
- UGF: 15Hz on all DOFs
- Phase margin > 45deg
- Gain margin>20dB
- Gain peaking <2

The HEPIs are tuned using the following parameters:
- Blend IPS-L4C at 800mHz
- UGF: 10Hz
- Phase margin > 45deg
- Gain margin>20dB
- Gain peaking <2

The measurements were performed using DTT, and then the spectra are extracted and calibrated using Matlab. In order to extract the data from DTT and save them in a .mat file, I used the Matlab and the python scripts called respectively ddt2mlab.m and ddt2mlab.py found in userapps/trunk/cds/common/scripts/dtt2mlab. Due to a bug, I modified (a hack, not a fix) ddt2matlab.py and dtt2matlab.m but I didn’t commit the changes.

The Calibrated spectra presented in attachment were measured in the following configurations:
-          HEPI ON - ISC Y - No Sensor Correction - ISI Damping
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping + Isolation with ST1 L4C blended at 250mHz
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping + Isolation with ST1 L4C blended at 250mHz + ST2 GS13 blended at 100mHz
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping + Isolation with ST1 L4C blended at 100mHz + ST2 GS13 blended at 100mHz
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping + Isolation with ST1 T240 blended at 250mHz + ST2 GS13 blended at 250mHz
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping + Isolation with ST1 T240 blended at 100mHz + ST2 GS13 blended at 250mHz

The plots show spectra of the length of the cavity (LHO_OAT_ALS-Y_ARM_LONG_IN1_DQ_2012_09_06.pdf), the motion of stage 1 (LHO_OAT_ISI-ETMY_ST1_BLND_Y_T240_CUR_IN1_DQ_2012_09_06.pdf) and stage 2 (LHO_OAT_ISI-ETMY_ST2_BLND_Y_GS13_CUR_IN1_DQ_2012_09_06.pdf) of ISI-BSC6 (ETMY). The mystery noise (fiber?) mentioned in 4128 slightly disturbed the measurements; it is visible on some spectra (on the black curve of LHO_OAT_ALS-Y_ARM_LONG_IN1_DQ_2012_09_06.pdf around 2 Hz for instance).

On the spectra of the cavity, the effect of the sensor correction on the HEPIs is noticeable (blue vs green). In both cases, the ISIs are only damped. However, there is a significant amplification below 100mHz (corner frequency of the STS-2 (on the ground) high pass filters at 40mHz). Above 100mHz, there is a reduction by a factor of 3-4 visible up to 2-3Hz.
Once the isolation filters are engaged on stage 1 only (blend at 250mHz on the L4C – in red), the attenuation is important above 250mHz and the amplification is still visible below 100mHz (should be amplified by the stage 1 CPS low blend filters).
Next, stage 2 isolation filters were also engaged and blend frequencies were lowered down to 100mHz and finally the T240s were introduced in the stage 1 super sensor (CPS + T240 + L4C). The extra isolation (low blend + T240s + 2 stages controlled) provided by the ISIs is not visible on the cavity above 200mHz (reaching the noise floor of “something”). Only the amplification below 100mHz is visible due to the use of aggressive blend filters (100mHz) and the 2 stages of isolation. The largest amplification is obtained when the 2 stages are controlled and the position sensors are blended with the seismometers at 100mHz.

The isolation provided by the ISIs is presented in figures (stage 1 - LHO_OAT_ISI-ETMY_ST1_BLND_Y_T240_CUR_IN1_DQ_2012_09_06.pdf) and (stage 2 - LHO_OAT_ISI-ETMY_ST2_BLND_Y_GS13_CUR_IN1_DQ_2012_09_06.pdf). The best isolation is obtained when the T240s are introduced in the stage 1 super sensor with a blend frequency of 100mHz. Actually, the CPSs are blended with the T240s at 100mHz and the T240s with L4Cs at 2Hz (cf scheme control).

Comments on the amplification at low frequency (peak at 60mHz)?
 At 60 mHz, when the ISIs are not controlled, the ISIs absolute motions are about 1 micrometer and the relative motion between the 2 ISIs is 100nm. A transfer function from the STS-2 at the end station to the STS-2 at the corner station showed that the LVEA and the end station are moving in phase around 100mHz (a 5-6 degrees phase would explain the 100nm of relative motion between the ISIs).
Once controlled, the absolute motion of the ISIs is amplified by 10 but what is the phase between the 2 ISIs? I tried to measure transfer functions from the T240s in BSC6 to the T240s in BSC8 but the coherence is close to zero.
Under control, the relative motion between the 2 ISIs is 10^4nm (x100 amplification). A phase of 60 degrees between the ISIs would explain that. But, it would be surprising to see this large phase since the filters used on both ISIs are quasi identical.

At low frequency, the platforms are locked to the ground using the position sensors. But if the so called vertical position sensors are not all “perfectly” aligned with the vertical, a translation of the platform in the horizontal plan will create some tilt. Under control, if the ISIs are moving in phase in the Y direction but one ISI is tilting in +Rx while the other one is tilting –Rx, the variation of the length between the test masses hanging points will be increased.

The tilt correction has not been implemented on the ISIs. Few weeks ago, I quickly tried but I didn’t see any significant improvements. It may be worth trying again.

[Rodica, Suresh]  Sun Sep  9 14:14:59 PDT 2012    

We found a dust alarm arising from H0:PEM-EY_DST1_3   .  Don't know if this a serious concern or if it is a false alarm.   Thought it is best to log it for site managers to look at.

Joe D, Cheryl, Rodica

With the most invaluable help from Joe D we got the TGG crystals completely restored to their shine yesterday. With the crystals in their holders we flushed freon inside the tubes and perfectly removed all contamination.

Cheryl and I reassembled the Quartz crystal with new strips of indium foil and closed the second assembly for the single TGG crystal and brought everything back inside the PSL enclosure.

We also cleaned the inside of the dust shield of the magnet with vectra alpha wipes and IPA.

Fiber was swapped from optics lab refcav to the PSL.

At the fiber patch panel in the MSR, the power we're getting from the optics lab refcav was about 3.3mW while our new PSL fiber provides 1.1mW or so.

Everybody had something else to do, so nobody was able to take care of the PLL. We'll continue working on it on Monday.

• Apollo moving cleanroom to HAM3
• Thomas running tests on ringheater
• Mechanical room vacuum system went down at the end of the day, Richard and Dave rebooted the frontend to get it back
• Ken working on cabling at EX

Jim, Greg, Mitchell, & Jason (IAS)

We got the Risers & Support Table into the Chamber Tuesday (Corey).  Wednesday we stayed pretty quiet.  Thursday we torqued the Support Table to Support Tube bolts and then surveyed the Support Table for vertical.  It was level to +-0.1mm but low 0.8mm.  Today we pulled the East door and IAS gave us horizontal moves.  This afternoon we moved the dial indicators from HAM2 to HAM1, floated the system and moved the position and adjusted the elevation (based on the DIs).)  We have a little more adjustment in horizontal now but ran out of time so we locked up the HEPI stops after adjusting the F-Clamp position where needed.
Next week we'll do a couple more tweaks and be ready for IAS to do another check.  We'll then lock up HEPI again and attempt a stress relieve on the Springs.
Finally we'll get back to building the isolation stacks and installing the Optical Table.

A newly-found RCG bug has been submitted as Bugzilla bug #415 to document recent findings in SUS that indicate three different file-name structures are created by the latest RCG code (2.5.1) to generate the generic MEDM screens. In the local directory, '/opt/rtcds/lho/h2/medm/', the RCG-generated MEDMs are written and sorted based on the individual model's name.

As an example, the directory for the H2 SUS ITMY ('/opt/rtcds/lho/h2/medm/h2susitmy/') generic MEDMs contains file-names of generally two structures:
1.) H2SUS_ITMY_* 
and 
2.) H2SUSITMY_ITMY_* 

A third structure was recently discovered:
3.) H2SUSITMY_*
(Note the difference between (2.) and (3.) is the second "*ITMY*" is missing.) 

This third structure seems to only apply to the ADC, DAC, GDS, BIO, and ALARM MEDMs.

From initial alignment data, we know the following:

Positive offset in PIT (H2:SUS-ETMY_M0_OFFSET_P and H2:SUS-ITMY_M0_OFFSET_P) will tilt the mirros such that the reflected beam off of the mirrors will go down.

Positive offset in YAW will tilt the mirrors such that the reflected beam off of the mirrors will go toward the inside of L.

That is, the upper stage of ITM looks like the mirror image of the ETM. Why is this the case? I thought that they are identical.

Also, I think oplev sign is somehow wrong. It's not consistent with initial alignment data.

FYI, the sign of the things in initial alignment was figured out by:

First using baffle diodes to figure out the sign of the TMS to figure out the TMS sign, and make the first beam hit the center of the ITM.

Then using ETMY cage and CCD camera, make the reflected beam from the ITM hit the cage bars to figure out the sign of ITM.

Then move offset of ETMY so that the beam comes back to the table, then move TMS and repeat, to see if ETMY sign is the same as TMS (it is).

As you can see, there is not much ambiguity there.