All the optcs were excited

Sat Sep 10 02:14:11 PDT 2011
999681266
 

The interferometer was coarsely aligned.

Now spatially overwrapped DRMI and FP arm fringes are visible on the AS camera although the incident beam alignment was done only with PZT2.

All the DC biases were saved so that we can go back to this condition any time.

/***** some health checks *******/

 [FINE] IPPOS : it looks okay but the spot on the QPD is a little bit too low by a few mm.

 [NOT GOOD] IPANG : maybe hitting a post or something because the spot is vertically split into two. The spot is too low.

 [FINE] POX/POY/POP : they all are coming out. POP is visible with an IR viewer.

 [FINE] REFL :  no clipping but the beam looks a little bit too low relative to the CCD camera.

 [FINE] AS : no clipping and the spot position on the AS camera looks fine.

 [FINE] Green beams : both X and Y beams are successfully landing onto the PST table without no clipping.

 [FINE] Suspensions : all of them are reasonably quiet without the oplevs, which is good.

The spot positions on the MC mirrors were readjusted.

All the amount of the off-center became smaller than 2 mm, which meet requirements of the beam clearance on the Faraday.

 In order to improve the MC1-YAW and MC3-YAW spot positions, the angle of the incident beam has to be shifted by approximately 1/100 rad.

However it turned out to be very difficult to introduce such amount of angle only with the steering mirrors on the PSL table since we have to keep the same translation while changing the angle.

By looking at what Daniel used in the low noise EOM Driver for aLIGO, we found the A2CP2596 from Cougar.

G = +24 dB, NF = 5 dB, Max Out = +37 dBm. It comes in a 2-stage SMA connector package. I've asked Steve to order 2 of them with the appropriate heatsinks.

The spot positions on the MC mirrors were measured in the vacuum condition.

The obtained spot positions are quite bad and roughly at 2-3 mm level. We have to realign the beam axis and the MC mirrors.

The OSEM pictures taken in Sep/6 have been uploaded to Picasa.

https://picasaweb.google.com/foteee

Something happened about 8 years ago.

Old iLog entry by AJW (2003/Sep/8)

Old iLog entry by AJW (2003/Sep/9)

Last night I noticed that PZT1 didn't work properly

I am not sure what is going on. Today I will try localizing the cause of the problem.

As far as I remember it was perfectly working at the time just after we readjusted the OSEMs on MC1 and MC3 (Aug 23th)

The symptoms are :

  + No response to both pitch and yaw control from EPICS (i.e. C1:LSC-PZT1_X and C1:LSC-PZT1_Y)

  + When a big value (-3 or so) from EPICS was applied, the PZT1 mirror suddenly jumped.

     However it turned out it just corresponded to a state where OOR (Out Of Range) LED lights up.

I did some brief checks :

  + checked the voltage going into the HV amplifiers' "MOD" input. Those are the voltage coming out from DACs and controlled from EPICS.

   --> looked healthy. They went from -10 to 10 V as expected (although the HV amp takes up to only +/-5V).

  + swapped the ''MOD" input cables such that C1:LSC-PZT1 controls the PZT2 HV and vice versa.

    --> The PZT2 mirror was still controlable, but the PZT1 mirror still didn't move. So the DAC and EPICS are innocent.

  + swapped the D-dub cables, which are directly going into the feedthroughs, such that the PZT1 HV drives the PZT2 mirrors and vice versa.

    --> the PZT2 mirror became unable to be controlled. For the PZT1 mirror, only PITCH worked smoothly.

[Suresh / Kiwamu]

 The attenuator was removed and now the MC is happily locked with the full power of 1.2 W.

(what we did)

 + replaced the perfect reflector, which was before the MCREFL_PD, by a 10% beam splitter like it used to be.

 + removed the attenuator (combination of HWP and PBS).

 + realigned the beam path on the AP table, including the MCREFL path and WFS path.

 + made the aperture of the MC2F camera narrower in order to avoid a saturation.

 + aligned the MC suspensions so that it resonates with the TEM00 mode.

 + put a ND filter on the AS camera

(notes)

C1:IOO-MC_RFPD_DCMON = 0.98 (locked)

C1:IOO-MC_TRANS_SUM = 17500 (locekd)

(next things to do)

 + measurement of the spot positions on each MC mirror.

 + centering of the beam spot by steering the input mirrors on the PSL table

We tried not to open chambers above 10,000 particles of 0.5 micron cf/min

New items going in:                       2 rasor beam traps, 5 badly oxidized old silver plated  setscrew with spring loaded tips......to be replaced in the future, viton tips for eq screws....some are lose, gold plated allen wrench installed at ITMX bottom, reglued magnet on ITMX

Bad hardware things found:          nylon ball "locking elements" on OSEM locking set screws with screwdriver  slot, lose  1064 nm filter on OSEM pd

Vacuum status:  " vacuum normal"   CC1 pressure 5e-5 Torr

Slow roughing through butterfly valve took 11 hours at 1-2 Torr/min speed.  We had a leak at the metal hose connecting o-ring  that became visible  at 200 Torr.

The vacuum envelope pressure rose to 500 mTorr from 450 mTorr  This is 50 mTorr leak plus outgassing over 11 hrs  over night stop =  5  mTorr /  hr

Atm2, Maglev pumpdown details. P2 and P3  are in the foreline of the Maglev. The pressure peaks at 4 Torr beacause the 3 drypumps have  little pumpimg speed at this range.

            External fan is turned on during this one hour period to prevent  Maglev turbo from overheating.

            Same things are  happenning with the two small TP2 and TP3 pumps under load. Their foreline pressure peak at 1 Torr.  They slow down to 45 K RPM from 50K RPM  and warm up to 36-39 C

Precondition: 36 days at atm

After Steve pointed out the 'deep hoop' issue, we decided to examine putting an RF Amp on the PSL table, between the RF combiner and the triple resonant box.

This will reduce the chances of standing waves in the cables and reduce the radiation induced pick-up in the RF PD and Demod electronics.

We would like to send ~10 dBm from the distribution box to the combiner. We also want to able to get as much as ~33 dBm of drive at 11 and 55 MHz. So the amp should have a gain of ~20-30 dB and an operating range of 10-100 MHz.

Also desirable are low distortion (high IP3) and good reverse isolation ( > 40 dB).

Some possibilities so far (please add your RF Google Results here):

1) Mini-Circuits ZHL-1-2W-S:  G = +32 dB, Max Out = +33 dBm, NF = 6 dB, Directivity = 25 dB

2) Mini-Circuits TIA-1000-1R8:  G=+40 dB, Max Out = +36 dBm, NF = 15 dB   (AC Powered, Inst. Amp), Directivity = 58 dB.

3) Mini-Circuits ZHL-2-8: G = +27dB, Max out = +29 dBm, NF = 6dB, Directivity = 32 dB

4) RFbay MPA-10-40: G = +40dB, Max Out = + 30 dBm, NF = 3.3 dB, Rev Iso = 23 dB

5) No proper stuff from Teledyne Couger

I stopped puming at 9:30 PM and the pressure in P1 is at 450 mtorr.

I followed exactly he procedure that Steve noted on his elog entry.

Here is a plot of the histroy of our pumping today.

Elog crashed / dormant for long time.  A look at the log file indicated that it was busy generating png thumbnails for pdf files.

Restarted at Wed Sep  7 20:41:13 PDT 2011

 We are at 30 Torr of 7 hours of pumping with 2 roughing pumps.

Kiwamu will take over the rest of the roughing today. He will keep an eye on  the pumping speed to be  ~1-2 Torr/min  and open up the manual RV1 valve if needed.

The present status is #3023 of  "chamber open to vacuum open" mode and waiting the P1 pressure to drop to 500 mTorr

He will do the following to stop pumping at P1 = 500 mTorr

1, close V3

2, close RV1 with torque wheel

3, turn off PR1 & 3

4, disconnect metal hose between RV1 and PR3

 I will start the Maglev tomorrow morning.

The measurement itself wasn't good.

I looked at the full 2 kHz data which was taken during the time when I was running the arm loss script on the X arm.

The plot below shows the raw data. The X arm was locked and unlocked sequentially several times.

The ASDC power didn't show a significant difference between the state where it is locked and unlocked.

I am not sure why, but It could be because of a misalginment or some kind of mode-mismatching, which can decrease the coupling efficiency of light going into the cavity.

(some notes)

The raw data were analyzed.

I split the ASDC data into two data, (1) low power state, when the cavity is locked (2) high power state, when the cavity is unlocked.

Then each state was averaged to estimate the averaged ASDC power in each case.

The number I obtained are :

    ASDC when X arm was locked = 54.77755 cnts

    ASDC when X arm was unlocked = 55.45830 cnts

Those numbers correspond to a round trip loss of  78.780778 ppm, which sounds too small for me.

Here are the results of the arm loss measurements, which I have done before the vent.

I ran the existing matlab script, called 'armLoss.m', to estimate the loss. The script resides in /scripts/LSC.

(Y arm)

 Round trip loss =  154.668624 +/- 11.343204 ppm

The figure above is a time series of the measurement.

In the lower plot the power in the ASDC_PD are plotted. The green dotted-curve is the power when the Y arm is unlocked.

The blue dotted-curve is the one when the Y arm is locked.

In the upper plot the estimated loss from each combination of locked/unlocked power are plotted.

(X arm)

Round trip loss = ????? 50 ppm ?????

The obtained time series looked wired because difference in the ASDC power when the arm was locked/unlocked were small.

This small difference results in such a small loss.

To see what was going on I will look at the trend data.

 ITMY has been upgraded  here I have the new lenses on hand to do the others when it fit into the schedule.

Jamie and Steve

We closed ITMX and ITMY chambers and started pumping around 11am

What we did before:

1, turned off AC power  to PZT Jena HV ps

2, checked jam nut positions

3, cheched  single o-ring shims

4, closed psl out shutter

Here are all suspension diagonalization spectra before close up. Notes:

• TMX looks the worst, but I think we can live with it. The large glitch in the UL sensor at around 999423150 (#5355) is worrying. However, it seemed to recover. The spectra below were taken from data before the glitch.
• ITMY has a lot of imaginary components. We previously found that this was due to a problem with one of it's whitening filters (#5288). I assume we're seeing the same issue here.
• SRM needs a little more data to be able to distinguish the POS and SIDE peaks, but otherwise it looks ok.

ITMX		pit     yaw     pos     side    butt UL    0.355   0.539   0.976  -0.500   0.182  UR    0.833  -1.406  -0.307  -0.118   0.537  LR   -1.167   0.055   0.717  -0.445   0.286  LL   -1.645   2.000   2.000  -0.828  -2.995  SD   -0.747   0.828   2.483   1.000  -1.637	8.01148
ITMY		pit     yaw     pos     side    butt UL    1.003   0.577   1.142  -0.038   0.954   UR    0.582  -1.423   0.931  -0.013  -1.031   LR   -1.418  -0.545   0.858   0.008   1.081   LL   -0.997   1.455   1.069  -0.017  -0.934   SD   -0.638   0.797   1.246   1.000   0.264	4.46659
BS		pit     yaw     pos     side    butt UL    1.612   0.656   0.406   0.277   1.031   UR    0.176  -1.344   1.683  -0.058  -0.931   LR   -1.824  -0.187   1.594  -0.086   0.951   LL   -0.388   1.813   0.317   0.249  -1.087   SD    0.740   0.301  -3.354   1.000   0.035	5.49597
PRM		pit     yaw     pos     side    butt UL    0.546   1.436   1.862  -0.345   0.866   UR    1.350  -0.564   0.551  -0.055  -0.878   LR   -0.650  -0.977   0.138   0.023   0.858   LL   -1.454   1.023   1.449  -0.268  -1.398   SD    0.634  -0.620  -0.729   1.000   0.611	5.78216
SRM
ETMX		pit     yaw     pos     side    butt UL    0.863   1.559   1.572   0.004   1.029   UR    0.127  -0.441   1.869   0.480  -1.162   LR   -1.873  -0.440   0.428   0.493   0.939   LL   -1.137   1.560   0.131   0.017  -0.871   SD    1.838   3.447  -0.864   1.000  -0.135	5.5259
ETMY		pit     yaw     pos     side    butt UL   -0.337   1.275   1.464  -0.024   0.929   UR    1.014  -0.725   1.414  -0.055  -1.102   LR   -0.649  -1.363   0.536  -0.039   0.750   LL   -2.000   0.637   0.586  -0.007  -1.220   SD    0.057  -0.016   1.202   1.000   0.142	4.22572
MC1		pit     yaw     pos     side    butt UL    0.858   0.974   0.128   0.053  -0.000   UR    0.184  -0.763   0.911   0.018   0.001   LR   -1.816  -2.000   1.872   0.002   3.999   LL   -1.142  -0.263   1.089   0.037   0.001   SD    0.040   0.036  -0.216   1.000  -0.002	5.36332
MC2		pit     yaw     pos     side    butt UL    1.047   0.764   1.028   0.124   0.948   UR    0.644  -1.236   1.092  -0.088  -0.949   LR   -1.356  -0.680   0.972  -0.096   1.007   LL   -0.953   1.320   0.908   0.117  -1.095   SD   -0.092  -0.145  -0.787   1.000  -0.065	4.029
MC3		pit     yaw     pos     side    butt UL    1.599   0.343   1.148   0.168   1.101   UR    0.031  -1.647   1.139   0.202  -1.010   LR   -1.969   0.010   0.852   0.111   0.893   LL   -0.401   2.000   0.861   0.077  -0.995   SD   -0.414   0.392  -1.677   1.000   0.018	3.61734

All fine, except ITMX_sensor_UL's  60  counts deep hoop for an hour.

Steve and Jamie:  After Jamie checks the ITM free swingings, please put on the ITM heavy doors and start the pump!  For real this time!!! Yeah!

I just started a freeswing all, as a final check before we pump:

Wed Sep  7 00:43:21 PDT 2011
999416616

Wed Sep  7 00:43:32 PDT 2011
WATCHDOGS WILL BE RESET 5 HOURS AFTER THIS TIME
sleeping for 5 hours...

Jamie: Please do a quickie analysis (at least for the ITMs) before helping Steve with the heavy doors.

I closed the PSL shutter.

Both ITM chambers were checked for tools, so there should be nothing left to do but put the heavy doors on, and begin pumping.

(What we did)

* Moved SUS to edge of table for OSEM adjustment.

* Leveled the table in this temporary tower position.

* Rotated all OSEMs to give some seperation between magnets and LED/PD packages.

* Moved the upper OSEM bracket a little bit upward.

* All the OSEM holding set screws were short with flat heads; this is annoying since we would like to use them more like thumbscrews. Steve took the long set-screws out of the old ITMX cage and we swapped them. Need to order ~100 silver-plated socket head spare/replacements.

* Took pictures of OSEMs.

* Moved tower back to old position.

* Releveled the table (added one rectangular weight in the NW corner of the table).

* Find that ITMX OSEMs were a couple 100 micron out of position; we adjusted them in-situ in the final position of the tower, trying not to rotate them. All mean voltages now are within 100 mV of ideal half-light.

* Back/front EQ positions adjusted by the screw method. bottom/top stops adjusted earlier.

* OSEM cables tied down with copper wire.

* Increased the incident power up to 91 mW going into MC to temporarily make the POX beam more visible.

* The POX beam was checked. It was exiting from the chamber and going through about the center of the viewport.

[Jenne, Suresh]

We did the following things in the ITMY chamber today:

1) We tried to get the ITMY stuck again by adjusting the coil gains so that it goes into the orientation where it used to get stuck.  We (reassuringly) failed to get it stuck again.  This, as we came to know later, is because kiwamu had rotated the side OSEM such that the optic does not get stuck . However the OSEM beam is at about 30 deg to the vertical and the SD is sensitive to POS motion now resulting in the poorer separation of modes as noted by Jenne earlier (5439)

2) We checked the earthquake stops and repositioned two at the bottom (towards the AR side of the optic)  which we had backed out earlier.

3) We took pics of all the OSEMS.

4) Checked to see if there are any stray beams with an IR card.  There were none.

5) I obtained the max values of the OSEMS by misaligning the optic with the coil offsets.  These values are in good agreement with those on the wiki

OSEM     UL     UR     LR     LL      SD

Max      1.80    1.53   1.68   1.96    2.10

Current  0.97   0.79    0.83   0.97   1.02

We can close the heavy doors tomorrow morning.

I just tried to adjust the ETMY camera and its not very user friendly = NEEDS FIXING.

* Camera view is upside down.

* Camera lens is contacting the lexan viewport cover; this means the focus cannot be adjusted without misaligning the camera.

* There's no strain relief of the camera cables at the can. Needs a rubber cable grommet too.

* There's a BNC "T" in the cable line.

Probably similar issues with some of the other setups; they've had aluminum foil covers for too long. We'll have a camera committee meeting tomorrow to see how to proceed.

[Rana and Kiwamu on ITMX, Jenne and Suresh on ITMY, Zombie/brains meeting on accepting the matricies]

Optic	Spectra	Matrix	"Badness"
ITMX		pit     yaw     pos     side    butt UL    0.584   0.641   1.396  -0.578   0.558  UR    0.755  -1.359   0.120  -0.286   0.262  LR   -1.245  -0.139   0.604  -0.388   0.511  LL   -1.416   1.861   1.880  -0.681  -2.669  SD   -0.753   0.492   3.263   1.000  -1.523	5.85983
ITMY		pit     yaw     pos     side    butt UL    1.000   0.572   1.134  -0.059   0.951   UR    0.578  -1.428   0.916  -0.032  -1.024   LR   -1.422  -0.531   0.866  -0.009   1.086   LL   -1.000   1.469   1.084  -0.036  -0.939   SD   -0.662   0.822   1.498   1.000   0.265	4.47727

 OSEMs were tweaked.  We have decided that both ITMs are okay in terms of their diagonalization.  ITMY isn't stellar when you look at the spectra, but it's kind of close enough.  Certainly the matrix looks fine.

Aside from checking on POX, I think we're now ready to close up.  Check back later tonight for a final decision announced on the elog.

I restarted the elog with the script as it was not up when I tried to make a post. It was again unresponsive when I went to submit, but this time the script couldn't restart it. The log said it couldn't bind to 8080, which usually happens if the daemon is still running. I pkilled it, then reran the script, and it appears to be working.

 I think Kiwamu accidentally restarted this kick at 17:48:02 PDT.

 Kiwamu excited ITMY (which Suresh had already started).  I just kicked ITMX:

Tue Sep  6 17:55:21 PDT 2011
999392136

Tue Sep  6 17:48:02 PDT 2011
999391697

Free swing of ITMY started at

Tue Sep  6 17:41:43 PDT 2011

These are the things that I can think of that we need to do before we can close up:

* Take a close look at both ITMs' OSEMs, and ensure that the magnets aren't too close to either plate in the OSEMs.  Both have had funny business over the past week.

* Do a free swinging test on both ITMs.  (ITMY may not need it, if we haven't touched it since the last free swinging test, but it can't hurt to take the data)

* Confirm that POX is exiting the chamber.

* Is there anything else???

Our goal is to finish this work by tonight, so that we can close doors and start pumping tomorrow.

[Jenne, Katrin, Jamie]

I'm a bad kid, and forgot to elog my Friday morning work...

Bob gave me back ITMX after a 48hour bake at 80C + clean RGA scan Friday morning after coffee and doughnuts.  Katrin helped me put it back in the suspension wire. 

While I was leveling the optic (making sure the scribe lines on each side of the optic are at the same height off the table), Katrin cut some new viton for replacement EQ stops.  The optic was missing one lower earthquake stop (the one that Jamie noticed last week), and somehow one other rubber piece came out of the EQ stop on another lower screw while we were re-suspending the optic.  We put the new stops in, and then checked the balance of the test mass.

The oplev is still the HeNe laser that is leveled to the level optical table in the cleanroom.  The lever arm is ~1.5 meters, and over that distance the reflected beam was pointed "up" in pitch by ~1.5mm, which is less than one beam diameter of the HeNe.  This is well within our ability to correct using the OSEMs.

We then locked the test mass, and installed it in the chamber.  I approximately did the half-voltage centering of the OSEMs, leaving the fine-tuning to Kiwamu for after lunch. 

 ITMX OSEMs   UL 1.8V,   UR 1.7V,   LR 0V,   LL 0V,   SD 1.3V  at the same bias setting shown above. May be a lose earth quake tip?or magnet is touching?

Restarted elog 9:11PM 9/5/11

(RF reflections)

The reflected RF power going back to the RF generation box will be :

    Power at 11MHz =  2 dBm

   Power at 29.5 MHz = 3 dBm

   Power at 55 MHz = 9dBm

Assuming the input power at 11 and 55 MHz are at 27 dBm (40m wiki page). And 15 dBm for 29.5 MHz.

Since there is an RF combiner in between the generation box and the resonant box, it reduces the reflections by an additional factor of 10 dB (#4517)

In the estimation above, the reduction due to the RF combiner was taken into account.

(Modulation depths)

Besides the reflection issue, the circuit meets a rough requirement of 200 mrad at 11 and 55 MHz.

For the 29.5 MHz modulation, the depth will be reduced approximately by a factor of 2, which I don't think it's a significant issue.

So the modulation depths should be okay.

Assuming the performance of the resonant circuit remains the same (#2586), the modulation depths will be :

      Mod. depth at 11 MHz =  280 mrad

      Mod. depth at 29.5 MHz = 4 mrad (This is about half of the current modulation depth)

      Mod. depth at 55 MHz = 250 mrad

It stacked again . We should take a closer look at it.

The new ITMX was aligned by changing the DC biases.

The resultant DC biases are reasonably small.

C1:SUS-ITMX_PIT_COMM = -0.2909

C1:SUS-ITMX_YAW_COMM = -0.0617

The alignment was done by trying to resonate the green light in the X arm cavity.

The spot position of the green light on the ITMX mirror looked good. This was confirmed by inserting a sensor card.

I did the OSEM mid-range adjustment and the rotation adjustment but at the end the OSEM DC voltage has changed due to the DC bias operation.

The OSEM rotation was approximately optimized so that all the face shadow sensors are sensitive to the POS motion but the SIDE shadow sensor is insensitive to the POS motion.

It needs a free swinging diagnosis.

What are the reflected RF powers for those frequencies? 
Is the 29.5MHz more problem than the 55MHz, considering the required modulation depth?

The triple resonant box was checked again. Each resonant frequency was tuned and the box is ready to go.

Before the actual installation I want to hear opinions about RF reflections because the RF reflection at 29 MHz isn't negligible.

It might be a problem since the reflection will go back to the RF generation box and would damage the amplifiers.

(Frequency adjustment and resultant reflection coefficient)

In order to tune the resonant frequencies the RF reflection was continuously monitored while the variable inductors were tweaked.

The plot below shows the reflection coefficient of the box after the frequency adjustment. 

In the upper plot, where the amplitude of the reflection coefficient of the box is plotted, there are three notches at 11, 29.5 and 55 MHz.

A notch means an RF power, which is applied to the resonant box, is successfully absorbed and consequently the EOM obtains some voltage at this frequency.

These power absorptions take place at the resonant frequencies as we designed so.

A good thing by monitoring this reflection coefficient is that one can easily tune the resonant frequency by looking at the positions of the notches.

Note that :

If amplitude is  0dB ( =1),  it means all of the signal is reflected.

If a circuit under test is impedance matched to 50 Ohm the amplitude will be ideally zero (= -infinity dB).

Reflections :

at 11 MHz = -15 dB (3% of RF power is reflected)

at 29.5 MHz = -2 dB (63% of RF power is reflected)

at 55 MHz = -8 dB (15% of RF power is reflected)

 Keiko, Kiwamu

Length tolerance of the vertex part is about 5 mm.

Sorry for my procrastinating update on this topic. In my last post, I reported that the length tolerance of the vertex ifo would be 2mm, based on Kiwamu's code on CVS. Then we noticed that the MICH degrees of freedom was wrong in the code. I modified the code and ran again. You can find the modified codes on CVS (40m folder, analyzeDRMITolerance3f.m and DRMITolerance.m)

In this code, the arm lengths were kept to be ideal while some length offsets of random gaussian distribution were added on PRCL, SRCL and MICH lengths. The iteration was 1000 times for each sigma of the random gaussian distribution. The resulting sensing matrix is shown as histogram. Also, a histogram of the demodulation phase separation between MICH and SRCL is plotted by this code, as these two length degrees of freedom will be obtained by one channel separated by the demodulation phase. We check this separation because you want to make sure that the random length offsets does not make the separation of these two signals close.

The result is a bit different from the previous post, in the better way! The length tolerance is about 5 mm for the vertex ifo. Fig.1 shows the sensing matrix. Although signal levels are changed by the random offsets, only few orders of magnitude is changed in each degrees of freedom. Fig.2 shows that the signal separation between MICH and SRCL at  POP55 varies from  55 to 120 degrees, which may be OK. If you have 1cm sigma, it varies from 50 degrees to 150 degrees.

Fig. 1 Histgram of the sensing matrix including 3f channels, when sigma is 5mm. Please note that the x-axis is in long 10.

 Fig. 2 Histogram of the demodulation phase difference between MICH and SRCL, when sigma is 5 mm. To obtain the two signals independently, 90 is ideal. With the random offsets, the demodulation phase difference varies from 55 degrees to 120 degrees.

My next step is to run the similar code for LLO. 

Suresh, Kiwamu and Steve

Heavy chamber doors replaced by light ones at  ITMX-west and ITMY-north locations.

Atm1, ITMY and the SRM are on the same isolation stack.  So why does  the SRM move twice as much?

Atm2, We should check the ITMY  SIDE_OSEM before pump down. Anatomically correct, beautiful picture taken by Kiwamu on August 22

The RGA back ground at day 29 of this vent.

[Kiwamu, Manuel, Jenne]

The new optics storage drawers have been populated with optics.  Each drawer is labelled.  Harsh punishments will be inflicted on anyone found disobeying the new scheme.

The pictures that we took are now on the Picasa web site. Check it out.

Uniblitz mechanical shutter installed in the green beam path at ETMY-ISCT  The remote control cable has not been connected.

I reverted the C1IOO model to the last working version and restarted the fb at this time..Tue Aug 30 17:28:38 PDT 2011

The ITMY mirror was released. The OSEM readouts became healthy.

To see what is going on, I changed the PIT DC bias slider on ITMY from 0.8 to -1 or so, and then the optic started showing a free swinging behavior.

If there were no responses to the DC bias, I was going to let people to open the chamber to look at it closer, but fortunately it released the optic.

Then I brought the slider back to 0.8, and it looked still free swinging. Possibly the optic had been stacked on some of the OSEMS as Jamie expected.