For future reference, the peak in the ISS_rpn spectrum at ~120Hz appears to be caused by the NPRO's noise eater. It also explains why I had to lower the reference signal to -2.5 from -1.9 to get the diffracted power to a reasonable level (33% down to 2%). This was fixed by turning the noise eater off and on. The attached plots show the noise eater noise (iss_rpn-009) and after it was reset (iss_rpn-001).

This was caused by swapping the FAST cable earlier last week. I was able to set the reference signal back to -1.9 afterwards.

Removed temporary connection used for PR2 testing and connected permanent cabling from HAM3 feedthrus to SAT Amplifiers.

I have put together 4 optics in the Faraday Isolator, out of 7 that should be there eventually. These include:

Ca wedge polarizer s/n 12 currently on the input side
Ca wedge Polarizer s/n 03 on the output side
TGG crystal s/n 10, presently on the "long" tube together with
Quartz rotator

Still not assembled are:

2nd TGG crystal -- will put s/n 09 in tomorrow when Al-Bronze cap is out of the C&B oven
HWP and DKDP -- don't yet have the proper mounts

To install Ca wedges I used a slightly different technique. I cut two 5 mm long sections of the Indium rod, and rolled them together into one fat 5 mm long rod. I then pressed that rod onto the setscrew, and still had enough Indium thickness to tighten on the Ca wedge.

The TGG is installed with Indium foil wrapped around the wedge. I had to roll two slices of the Indium foil together, as the lengths (or even the diagonals) of the foil squares that were delivered are shorter than the circumference of the crystal.

The Quartz is installed withOUT the foil. Instead it contains at least 3 layers of the Indium wire on the cap side to keep it in place.

More photos may be found on the Resource Space.

Attached are plots of dust counts > .5 microns in particles per cubic foot.

The Simulink models for the H1 HAM2 suspensions were modified today to add the IPC part broadcasting the watchdog state to the HAM-ISI model via the Dolphin network.  For now, the watchdog state is broadcasting a constant "0" to first test the communication between the FrontEnds. After confirmation, the constant will be replaced with the correct WD state. The error signals for the receiving models were also added as EPICS outputs.  The BIO IPC communication for the four models were also implemented via Shared Memory on the 'h1sush2a' FrontEnd.  The ability to compile the models was confirmed via the "make" command on the "h1build" machine.  These changes will be installed on "h1sush2a" tomorrow during the Maintenance Day period in the morning.

The models modified were:
"h1susmc1.mdl","h1susmc3.mdl","h1suspr3.mdl", and "h1susprm.mdl"

The models were committed locally to the directory:
'/opt/rtcds/lho/h1/userapps/release/sus/h1/models/'

This morning, several spectra were measured to evaluate the performance of the ISI-BSC6 with different blend configurations:

• Damping (green)
• Stage 1 blend at 100mHz with T240 - Stage 2 blend at 100mHz (brown)
• Stage 1 blend at 250mHz with L4C - Stage 2 blend at 250mHz (pink)
• Stage 1 blend at 100mHz with T240 - Stage 2 blend at 250mHz (red)
• Stage 1 blend at 250mHz with T240 - Stage 2 blend at 250mHz (black)

The plot LHO_ISI_ETMY_Isolation_aLOG_ST1_Y_20120820_2.pdf shows non calibrated spectra of the T240s in the Y direction. Around 500mHz, the isolation is slightly better with the T240 in the super sensor (comparison pink and black curves - In both cases, the blend is at 250mHz).
The blend on stage 1 can be lowered at 100mHz (red and brown curves).

The plot LHO_ISI_ETMY_Isolation_aLOG_ST2_Y_20120820_2.pdf shows non calibrated spectra of the GS13s in the Y direction. The isolation impprovement seen on stage 1 are also visible on stage 2.

On both ISIs (BSC6 and BSC8), the T240s can be introduced in the super sensor (cf https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=3858).

 

Serviced inter-cooler and after-cooler auto drain units

- OAT needs quiet today
- HAM5/6 and clean room cleaned
- 9AM, contractors to EX to install linolium
- 10AM - MichaelR to shut down PSL for power swap
- DaveF working in Laser Safe PSL w/glasses while the laser is down
- Keita to EY
- Patrick to LVEA
- Gerardo to LVEA test stand
- Eric to LVEA near rollup door
- Thomas near HAM4 doing Mode Cleaner Baffle assembly
- Jodi to EY to get ameristat
- Betsy, Calum, Norna, Lisa, Thomas,… out in LVEA

Fairly quiet day - some issues with DAC with planned fixes tomorrow - power swap on H1PSL - more work at EX preping for install - purge air fix in LVEA - some issues with OAT and Ref Cav unlocking.

Filiberto, Richard, Michael R

The PSL was moved off of the temporary power supplies for 24, 18 and 12V and is now running on the DC power supplies in the H1 electronics room. For the moment, we are still running on the temporary power supplies for high voltage (400V for PMC/ILS, and 180V for FSS), however they were moved into the PSL rack to free up room. The purple cables in the electronics room were redressed as well.

The PSL servos and laser were shutdown for this work, and the key from the control box was removed to make the laser and ante room laser safe (to make David Feldbaums work easier). I plan on turning the laser on tomorrow morning, so it will be off for the night. If all goes well with David's work we may go to high power tomorrow as well.

We ran a test on Friday to do scans measuring the cavity response to injected sidebands. These were run with the cavity cold and also with it heated. Unfortunately, the reference cavity lost lock before we turned on the ring heater. We locked up all the reference and arm cavity again after 2.5 hours of applied ring heater power. The cavity scan looked extremely noisy at this point - I think this indicated a noisy lock, rather than a severe mode-matching error. We lost lock on the reference cavity after 20 minutes or so and decided to call it a night.

The cold and hot cavity scans are attached below.

Details of the cavity scan measurement will be posted in another entry.

Yesterday the reference cavity could not stay locked for more than half an hour. Today I tried to improve the alignment to make the lock more stable. I doubled the transmitted power (from 45mW to 90mW on the monitor PD) by mainly chainging the alignemnt in Pitch.

The cavity stayed locked for 2.5 hrs but then the lock broke again for no apparent reason and despite the quiet at work today.

During the time it was locked, the arm lock was also good and stable. After re-aligning ETMY and ITMY I obtained 9000 cts at the REFL monitor PD for over 2hrs.

While the arm was lockedthe WFS sensing matrix. Like yesterday, I kep obtaining an almost degenerate YAW matrix. The Pitch matrix was better and the integrator in the ARM_POS_PIT and ARM_ANG_PIT loops appaeared to be stable.

Before continuing with the work on the WFS we have to understand why the reference cavity has become so unstable.

Attached are plots of dust counts > .5 microns in particles per cubic foot.

Ring heaters are ON at 630mA requested power.

start_time = 1029285549

[David F, Mike R, Deepak K]

We moved the Farday Isolator from the H2 PSL room to the H1 PSL room. We used the C Channel as base and covered it using C3 covers and wrapped the entire thing in a Ameristat bag.  We moved from the Chamber using a cart and Slid it under the beam tube. Then used a diferent cart to move it to the H2 PSL Chamber.

I estimated the magnification of the ETMY HWS optical path. To do this, I took a measurement of the beam profile on the HWS CCD (without the Hartmann plate in place) and fit a Gaussian beam profile to it. This was then compared to the theoretical beam size at the ETM within the cavity. Given that the cavity scans show very little higher mode content it is a safe assumption that the beam size at the ETM is approximately the cavity beam size (although I don't yet have an estimate on the error/uncertainty in this approximation).

Measured 1/e^2 beam radius at the HWS = 1.51mm

Nominal 1/e^2 beam radius at the ETM = 31.49mm

Magnification (HWS to ETM) = 20.83x

I've set up a cavity scan to run as often as the GPIB-Ethernet/SR785 system allows (~ every 165 s), in preparation for observing shifts after the ring heater is turned on later today. Excitation B of Common Mode A will be left on for the duration of these measurements.

(corey, jim)

Have Capacitive Postition Sensor (CPS) mini-racks in place under HAM2 and they were powered up so leveling could be performed.  While in the chamber we also cleaned up cabling a little.  All of this was in efforts to prep this ISI for Hugo-testing.

[This is for work from Thursday]

(corey, hugo, jim)

HAM-ISI#7:  Much of the day was devoted to helping out Hugo finish out items from his testing document (noting serial numbers, checking level, helping with tilt spectra measurements, etc.). 

BSC-ISI#4:  Optics Table Assy forklifted from granite table on to Stage0.  Blade Posts were helicoiled and (2) of them screwed on to Stage0 (not torqued though).  Did not put third one on because the dowel pin for it was a tight fit.

[Daniel and Bram]

With the appearance of the laser PZT resonance in the FIBR servo loop, we made a notch filter. We measured the PZT resonance in a previous entry 3857 to be at 287.55 kHz. After some searching and going back and forth we decided to go the easy way, using a passive notch filter (schematic attached 'FIBR_PZT_NOTCH.pdf'), which Daniel already has used in the TTFSS.

By the lack of finding the right capacitors, we used a 500 pF and a 100 pF parrallel, with a 0-100 pF variable capacitor (oh and we got a 470 uH SMD inductor!). With the help of EE-Dave we managed to pack it into a pomona box.

Also attached is a discustingly bad phone photo of the measured response (the RF analyser has a naughty floppy disk drive).

All in all success. We plugged it in and it worked, we can lock the FIBR Servo with a UGF of 28 kHz (another log entry will follow when I get the data from the disk).

One of the goals of the OAT was that the residual arm motion measured by the green beam, with the VCO to arm offloading, is about 10 nm or so for f<0.5Hz.

Attached is the calibrated residual motion in nm/sqrtHz. Solid lines are with both ISI isolated (non-aggressive crossover, without Trillium), and the dashed are with both ISI only damped. These are not a true A/B comparison (different lock stretches, different seismic level, only 7 averages) but are good enough to show you some ball park numbers.

1. Even though the isolation helps greatly at 1Hz, it makes a huge peak at about 40 to 50 mHz with the RMS of about a micro meter. This might or might not be larger than expected, but as I understand from Vincent we expect some amplification at this frequency.

2. With or without the isolation, 0.46Hz peak is also big. Isolation might be helping a factor of 2 or so but we need a factor of 20 or more.

3. Though it's outside the scope of the stated OAT goal, 1Hz peak is not negligible. Without isolation, this should be reduced by a factor of at least 5 or so.

Vincent might be able to refine ISI further, but we shouldn't expect HEPI/ISI alone to bring the residual RMS down to 10nm level (or even 50nm for that matter, stated goal of OAT for HEPI/ISI is 200nm RMS and we're already quite close).

Regardless of the ISI isolation, we need a more aggressive VCO offloading to the length. Right now VCO is only offloaded to the HEPI, and the UGF of this path is smaller than 10 mHz. We need to use another path to the ETM and/or ITM suspension if we want a larger UGF to suppress e.g. 0.46Hz peak.

The reason why no work has been done for this for a long time, I think, is because there was a huge POS to PIT coupling when you drive M0. What's the current status of drive diagonalization (don't confuse this with sensing diagonalization)?