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Reports until 22:49, Thursday 02 August 2012
H2 ISC
bram.slagmolen@LIGO.ORG - posted 22:49, Thursday 02 August 2012 (3711)
ALS-Y-PLL

[Elli and Bram]

After the OAT RefCav work, we relocked the PLL in EY. We had to tune the laser crystal temperature up to 42.27 degC (from 42.08 degC). We also teaked the waveplate, setting the beatnote power to -31dB.

H2 ISC
bram.slagmolen@LIGO.ORG - posted 22:40, Thursday 02 August 2012 (3708)
OAT RefCav

I had a look at the refernce cavity today to see where we losing our gain. Initially I tweaked the alignment increasing it by approximately 10%, the 01-mode is now much dimmer on the monitor (I didn't do a scanning alignment, and tried to kept the cavity locked).

Also, I rotated the QWP just infront of the cavity to maximise the power on the RF LSC diode. In the beam just after the PBS, which taps the beam for the RF LSC diode, is a ~90/10 beam splitter (unlabelled), directing 90% of the beam to a CCD camera! Due to a lack of looking for a smaller splitting ratio beam splitter I left it inplace, so we now geting ~4 mW onto the RF LSC diode (of the 34.4 mW available in the return beam).

I dropped lock, so I could measure the power. Into the cavity is 46 mW, reflected is (out of the PBS) 34 mW. I measured the power incident on the transmitted diode but forgot to measure the total power transmitted! There is 4 mW on the RF LSC diode (reading 169 mV at the DC output). Once locked the power drops to 40 mV out of the DC output.

The UGF is 287 kHz, with the folowing Interface Settings

Coaers Fine Common Fast Offset
340 512 800 680 294

It runs with Common at 850 and Fast at 700 (UGF 315 kHz), but it becomes more sensitive to bumping and floor motion and starts to oscillate.

You can recover from the oscillation by reducing the Common gain to below 160, and bring it back up.

The relock of the RefCav is at a slightly different mode, asI tweaked the coarse tuning down wards to find the 00-mode. There is 210 micro Watts on the transmitted diode, reading ~828 mV (it has a gain setting of 20 dB).

LHO General
patrick.thomas@LIGO.ORG - posted 20:05, Thursday 02 August 2012 (3710)
plots of dust counts
Attached are plots of dust counts > .5 microns in particles per cubic foot. The dust monitor at location 8 in the LVEA (H0:PEM-LVEA_DST8_5) was put in the assembly prep area near HAM2 and HAM3.
Non-image files attached to this report
H2 ISC
bram.slagmolen@LIGO.ORG - posted 17:53, Thursday 02 August 2012 (3709)
Arm Locking

Vincent finished installing the HEPI system. Because the ISC signals are now added into the HEPI feedback just after the compensation filters, the gain and sign have changed.

Now we have a gain of -2 (from +0.2). Also the units are not in nm anymore .... not a drama but makes thinking about limits a bit harder ...

I engaged the ISI isolation on ITM, but the ETM kept tripping so I left it in damping only (didn't further investigate).

Left the cavity locked for the night.

LHO VE
kyle.ryan@LIGO.ORG - posted 16:44, Thursday 02 August 2012 (3707)
More leak testing at Vertex output MC
Kyle 

With the leak detector configuration as left yesterday, i.e. backing the Vertex MTP (100% of the turbo exhaust) the helium background had decreased from 1.3 x 10-8 torr*L/sec (as left yesterday) to 6.2 x 10-9 torr*L/sec today -> I vented the HAM5 and HAM6 annulus volume and decoupled the HAM5 aux. pump components leaving the pump port connection open to the room.  Then I let the HAM6 aux. cart diaphram backing pump pump air through the annulus, i.e. room air enters HAM5 pump port and routes through annulus volume and exits HAM6 pump port.  This was another attempt to expedite removal of any helium permeated in the annulus O-rings -> No help, too slow.  Next I calibrated our 2nd leak detector and swapped it in place of the initial leak detector -> No change.  It measured and behaved within 10% of the first.  This was done to rule out any instrument-specific inability the initial leak detector might have had in resolving helium ions from non-helium ions in the spec. tube (as the leak detector inlet pressure is relatively "high" baking the MTP).  This concludes my attempt to get the helium background to the nominal <2 x 10-9 torr*L/sec value.  

Moving on, I reconnected the initial leak detector and began testing CF joints on the output MC tube with a background of 6.2 x 10-9 torr*L/sec.  Two of the first three flanges I tested were 10-6 range leakers!! Ouch!!  Will have to continue tomorrow after this pumps away.  
LHO General
corey.gray@LIGO.ORG - posted 16:10, Thursday 02 August 2012 (3647)
Day Shift Ops Summary

Day's Activities:

Since there was not OAT activities during the day, this allowed for noisy activities in the LVEA/EY.

H2 SEI
vincent.lhuillier@LIGO.ORG - posted 15:44, Thursday 02 August 2012 (3706)
HEPI model modifications - BSC6 - BSC8

This morning, the HEPI master model was updated, corrected and committed. The two HEPI models (BSC6 and BSC8) were recompiled, re-installed, restarted and restored. The safe burt snapshots were updated. Bram was able to lock the cavity with the new configuration.
Note that the Yaw offset is now introduced in the DC_BIAS and the ISCMON filter output signals are not going through the isolation filters.
Now, ISC signals can be read by the HEPI models using the reflective memory.

H1 SUS
betsy.weaver@LIGO.ORG - posted 14:20, Thursday 02 August 2012 (3705)
H1 PR2 work

After the false start with damping measurements earlier, I went in and center the M2/M3 lower stage AOSEMs.  Unfortunately, we broke a magnet off of the temporary lowest mass during transport/rehanging, so LR AOSEM is not "seeing" anything.  We'll skip repairing it since we are about to move on to installing the real glass mass shortly.  I just turned damping on again now.

LHO General
robert.schofield@LIGO.ORG - posted 13:38, Thursday 02 August 2012 (3704)
Attempts to explain S5 H1-H2 coherence

I would not normally put this here, but the stochastic log was unavailable.

To build our confidence in our understanding of instrumental H1-H2 correlations, we are attempting to identify the features in the H1-H2 coherence. I did this for part of the S5 data back during S5 (here), when I was able to trace many of the features to particular sets of fans, or to low frequency (0-15 Hz) BSC and HAM resonances in the bilinear coupling regions around 60 Hz peaks; the summary from 2006 is repeated here as Figure 1.

Here we check these earlier results with full-S5 data, making sure that the rest of the run is consistent with the earlier partial results by comparing the full-run and partial-run features in coherence and by comparing the full-run PEM spectra to the full-run coherence.

A comparison of Figure 1 and Figure 2 indicates that the clusters of peaks from certain fans and the bilinear coupling features are present in both the partial run and the full run, suggesting that the specific partial-run identifications could be extended to the full run.

We expect that peaks in the H1-H2 coherence are associated with peaks in important PEM channels (sensors at coupling sites or half way between H1 and H2 coupling sites). The full-run PEM spectra of important channels show peaks that correspond with the coherence features, except for the peak at 114 Hz. The 114 Hz peak in Figure 1 is the only peak labeled “uncertain” – there were fans in this frequency band, but the shape of the peak did not quite match the shape in the partial-run spectra. This is again true for the full-run spectra, so I am not confident that we understand the source of the 114 Hz peak in coherence.

We are currently looking into the possibility that a sudden change in coupling when I floated ISCT4 to reduce H1 H2 coupling might be responsible for the inconsistency in coherence and ASDs. 

Images attached to this report
Non-image files attached to this report
H1 SUS
betsy.weaver@LIGO.ORG - posted 11:36, Thursday 02 August 2012 (3703)
H1 PR2 Damping ON

I've turned the damping on for PR2 (chamberside, all metal HSTS) at 18:34 UTC / 11:32 PT, in order to take some damped spectra.  Motion on the optic looks steady as per the speed dials.

H2 ISC
bram.slagmolen@LIGO.ORG - posted 10:28, Thursday 02 August 2012 (3701)
ALS Laser TEC response

(not Bram)

Attached is a plot of the response of the laser crystal TEC when stepping 13mK up and then down at the slow input (assume -1K/V sensitivity). The response shows a spike by about +9mK and then -9mK (not clear how good either calibration is). The response time is roughly 5 sec which would indicate a ~30 mHz pole in the slow input of the laser.

Images attached to this report
H1 SUS
jeffrey.kissel@LIGO.ORG - posted 08:24, Thursday 02 August 2012 (3699)
H1 SUS MC2 Phase 2b Results
B. Bland, J. Kissel

[[ These results are extremely belated, but I want to post them for posterity. ]]

After making adjustments to the static Roll of the optic, we've remeasured (as much as we remembered to of) H1 SUS MC2. Attached are the results.

Several things that these results indicate:

- The alleviation of the DC/static roll in the optic appears to have restored normalcy on the lowest L and T mode, i.e. they're no longer split in frequency. Huh!
- Now all degrees of freedom match well with the model, and other degrees of freedom.
- Spectra compared against in-chamber LLO suspensions indicate that excess noise seen at high-frequency is indeed most likely due to the noisy external environment on the optical tables. However, you'll notice that the noise has significantly reduced from when the SUS was in LHO staging building, so this confirms that the LHO assembly area is simply the noisiest environment where testing takes place, and it's not a problem fundamental to the suspension itself.


As of these results, H1 SUS MC2 has passed Phase 2b testing and is ready for install into HAM3.
Non-image files attached to this report
H2 ISC
alberto.stochino@LIGO.ORG - posted 20:31, Wednesday 01 August 2012 (3698)
Leaving arm locked overnight

I re-locked the arm, after I had unlocked it earlier to take some measuremens with the ALS table PZTs.

I'm leaving it locked overnight.

H2 ISC
alberto.stochino@LIGO.ORG - posted 20:26, Wednesday 01 August 2012 - last comment - 10:29, Thursday 02 August 2012(3697)
ALS QPD loops closed with Cartesian input and output matrices

I replaced the old ALS QPD output matrices (measured empirically by Elli and Thomas several weeks ago) with new ones based on Cartesian coordinates. I obtained these by ray-tracing on the ALS table. Then I measured the input matrices with a Matlab script (/svn/cdsutils/trunk/ALS).

Now the inputs of the IP_POS and IP_ANG filter modules should be calibrated in meters and radians.

These are the matrices:

INPIT =
  -0.001934944012837   0.000295830132597
  -0.000025683755141  -0.000141436038465
INYAW =
   0.001338191005451  -0.000236296533156
  -0.000010597031521   0.000352368394300

OUTPIT =OUTYAW=
   1.0e+07 *
  -0.746993867828206   2.240981603484618
   0.048486940975147  -0.800820822925440

The loops have UGF of about 10 Hz with these gains:

IP_POS_PIT= -8; IP_ANG_PIT=-8; IP_POS_YAW=-8; IP_ANF_YAW=-4

Attached are some spectra measured with the loops either open or closed.

The TMS table relative lateral stability seems to comply with the requirements (=100urad RMS). On the other hand the angular stability seems to be a bit worse than desired (=1urad RMS).

Long term stability (12+ hrs) still has to be evaluated.

Non-image files attached to this report
Comments related to this report
daniel.sigg@LIGO.ORG - 07:51, Thursday 02 August 2012 (3700)
There seems to be a factor 2-3 gain peaking at 20Hz. The gain peaking seems to be responsible for most of the remaining rms. There are also lines at 60Hz and just below that are fairly large in the spectrum. Is this real motion or just sensor noise?

Also: pdf of 2nd file
Non-image files attached to this comment
alberto.stochino@LIGO.ORG - 10:29, Thursday 02 August 2012 (3702)

I multiplied the input matrices by 1e6 so that we read out um and urad at the input of the IP_POS and IP_ANG filter modules.

On all modules I enabled a filter called "cal" that divides that factor out.

LHO General
patrick.thomas@LIGO.ORG - posted 19:14, Wednesday 01 August 2012 (3696)
plots of dust counts
Attached are plots of dust counts > .5 microns in particles per cubic foot.
Non-image files attached to this report
H1 IOO
volker.quetschke@LIGO.ORG - posted 18:33, Wednesday 01 August 2012 (3695)
EOM Amplitude Modulation

[Michael R., Volker Q.]

After installing the new EOM and measuring the PM sidebands, see previous entry, we measured the RFAM on the core modulation frequencies 9.1MHz, 45.5MHz and 24.1MHz. All frequencies were driven with 10Vpp. The measurement was performed using a LZH aLIGO PSL locking PD (D1002163) mounted at the position of IO_AB_PD1.

The AC path of this diode has a 4x amplification with respect to the DC path and 50 ohm output impedance.  The DC path also has 50 ohm output impedance.

The DC value was measured with a TDS 2024 into high impedance, the AC output was measured with an Agilent 4395a into 50 ohm. (Note, this gives another factor of 2 for the DC value.)

The RFAM was calculated using this formula RFAM = (V_AC/4) / (V_DC/2) accounting for AC amplification and DC path impedance.  V_AC denotes the Vrms as measured with the spectrum analyzer and V_DC the voltage read from the oscilloscope. The PM value below is the modulation index as measured previously.  As a sanity check the V_AC measurements were done with the dBv, dBm and Volt settings of the spectrum analyzer to confirm that Vrms is displayed. The following table shows the measurements:

DC value in mV   PM 45.5 ampl. (dBV) 45.5 ampl. (dBm) 45.5 ampl. (uV)   RFAM  Frequency  RFAM/PM
930   0.31 -79.8 -66.8 103        
      1.02E-04 1.02E-04 1.03E-04 Vrms 5.50158E-05 45.5 MHz 1.77E-04
                   
      9.1 ampl. (dBV) 9.1 ampl. (dBm) 9.1 ampl. (uV)        
    0.39 -75.4 -62.4 172        
      1.70E-04 1.70E-04 1.72E-04 Vrms 9.13034E-05 9.1 MHz 2.34E-04
                   
      24.1 ampl. (dBV) 24.1 ampl. (dBm) 24.1 ampl. (uV)        
    0.14 -84.6 -71.5 61        
      5.89E-05 5.95E-05 6.10E-05 Vrms 3.16583E-05 24.1MHz 2.26E-04

The Agilent 4395a was set to BW = 3kHz.

H2 AOS
thomas.vo@LIGO.ORG - posted 17:15, Thursday 26 July 2012 - last comment - 16:26, Wednesday 08 August 2012(3614)
H2 ITMY/ETMY Optical Lever Calibration
Jeff K. , Thomas V.

Below are the calibration parameters for the H2 ITMY Optical Lever:
        Slope          Y-intercept
Pitch [ 580.41229822  -11.51774017]
Yaw  [ 689.70532274  -13.3345144 ]


And here are the calibration parameters for the H2 ETMY Optical Lever:
         Slope           Y-intercept 
Pitch [ 1666.80728788   -33.14694715]
Yaw  [ 1727.67131855     23.41350328]

Both sets of calibrations were attained via the same process of moving the QPD along a translation stage and measuring the output signal.  All four sets of slopes are in units of radian*meters.
Images attached to this report
Comments related to this report
thomas.vo@LIGO.ORG - 14:40, Friday 03 August 2012 (3713)
Jeff K. Thomas V.

We have found a non-linear relationship between the way the translation stage moves and the way we were reading out the measurements.  We need to double check the calculations as well as the methodology on retrieving data.  This latter is difficult because even though there is a micrometer on the translation stage it is covered by the laser enclosures, which if we take off, it will introduce ambient light onto the QPD.  We are currently investigating solutions.
jeffrey.kissel@LIGO.ORG - 11:59, Monday 06 August 2012 (3736)
T. Vo, J. Kissel

Pulling out a spare translation stage and measuring the displacement response (in [mm]) to controller demands (in [ct]), we found the following attached relation. Immediately turned off by the non-linearity seen, from our experience with the controlers jolting the translation stage upon power on/off, and from Kissel's recollection of the controllers in i/eLIGO (of which these controls are the same), we've launched into a more sophisticated characterization of the controllers. Given that the non-linearity is roughly 1 [um] over the 1 [mm] range measured, we might be barking up the wrong tree and just be over-reacting, but it should be a quick round of measurements to assess it in more detail.

It should also be noted that the controller can demand from 0 to ~8600 [ct], and we've thus far only exercised it from 0 to 150, since we only need ~1 [mm] range given the size of the Oplev QPD.
Non-image files attached to this comment
jeffrey.kissel@LIGO.ORG - 13:03, Monday 06 August 2012 (3737)
T. Vo, J. Kissel

Here're the results from the more detailed characterization. It looks like, within a small range of operation the controller is indeed linear to the desired level. However, over the full range of the controller, there's certainly some non-linearities present.


Notes:
Linear UP -- commanding the stage to move from 0 (4000) up to 150 (4150), in linear 10 [ct] increments.
Linear DOWN -- commanding the stage to move from 0 (4000) up to 150 (4150), in linear 10 [ct] increments.
Random -- going to each data point in a random order

Each of these should yield the same answer if it's a truly linear system.
Non-image files attached to this comment
thomas.vo@LIGO.ORG - 16:26, Wednesday 08 August 2012 (3758)
Jeff Kissel Thomas Vo

After reviewing the linearity of the translation stage as shown in ALOG 3737, we found that the non-linear regime of the translation stage resides near the end of the rails of the stage but the approximate middle yielded linear results.  We're confident that the increments that we used to translate the stage during calibration for both test masses were small enough and far enough away from the edges so that the non-linearity would have a small affect on our results, this will require further testing to truly be valid (in progress).  That being said, after correcting some errors in the calculations and double checking our numbers, we used the original data to apply to the calibration.  

A noteworthy point: Jeff Kissel used the edrawing from the solidworks model in,

LHO Corner Station: D0901469-v5 
LHO EY Station: D0901467-v6 

to find a more accurate number for the lever arms than previously used, ITMY = 56.4m and ETMY = 6.6m, as opposed to 70m and 6m respectively.  This was taken into account for our last calculation.

Onto the good stuff, the values of the slopes below are in micro-radians*meters:

ITMY
        Slope         Y-Intercept
Pitch [ 25.93274501  -0.51461109]
Yaw   [ 30.81584154  -0.5957635 ]



ETMY
        Slope         Y-Intercept
Pitch [ 54.53112025  -1.01505634]
Yaw   [ 56.56393367   0.79879263]


Attached are the graphs of the linear response curves, the python fitting scripts and the EXCEL spreadsheets to help visualize the underlying calibration calculations. In particular, the excel spreadsheets shows the conversion from controller units into millimeters and then into meters and micro-radians.  Hope this is the last time we'll need to repeat this post, sorry for the troubles!
Images attached to this comment
Non-image files attached to this comment
H1 SEI
hugh.radkins@LIGO.ORG - posted 13:28, Wednesday 25 July 2012 - last comment - 10:10, Friday 03 August 2012(3586)
H1 HAM3 HEPI Actutors Attached & Released--IAS says OK! Prt Duex
OK now we have all the HEPI Actuators attached & released at the correct elevation and IAS has signed off on the position.

Elevation & level is 0.1mm below nominal of -250.5mm (wrt LIGO Global) with a +-0.1mm levelness.

Attached is my field notes of the final dial indicator readings and the level survey-enjoy.

Thanks to Mitchell & Jason
Non-image files attached to this report
Comments related to this report
hugh.radkins@LIGO.ORG - 10:10, Friday 03 August 2012 (3712)
I misspeak above where I say wrt LIGO Global.  The number above, -250.5mm is the LIGO Global elevation corrected to the local leveling field.  The HAM ISI Optical Table is positioned to -252.9mm.  2.4mm is the correction to local level hence the -250.5mm; please pardon the confusion. -H
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