-- Alignment

     - C1ASS

     - MC WFS 

    - OPLEVs

-- Optimization of Suspended Optics

  - diagonalizations

  - damping control

  - upgrading of electronics

   - weekly check

-- Input Optics

   - PMC

         * mode matching
         * epics LO HI values

   - FSS and ISS

        * recover FSS
        * make ISS working

   - EOM

   - doubling and RFPD for green

-- Length Sensing and Control

   - digital system and electronics

-- Green Locking

    - X end station

    - Y arm green locking ==> Suresh/Bryan

    - digital control systems

      - noise budget

   - cavity scan and handing off

-- misc.

- Put priority on the list

- Put names on the items

- Where is the CDS TO DO ==> Joe

-

- Remote disconnection of the greeen PDH 

- What is the situation of the PD DC for the LSC PDs?

- SUS Satelite box Resister replacement ==> Jamie

- IMC mode matching ==> Jamie/Larisa 

- Mechanical shutters everywhere

- SRM OPLEV Connection

- MC OAF

- Better LSC whitening boards

- DAFI 

CDS To Do:

1) Get ETMY working - figure out why signals are not getting past the AI board (D000186) to the coils.

2) Get TDS and command line AWG stuff working

3) Get c1ass and new c1lsc (with Koji) fully integrated with the rest of the system.

4) Get CDS software instructions up to date and well organized.

5) Redo cabling  and generally make it a permanent installation instead of hack job:

   a) Measure cable lengths, check connectors, wire with good routes and ensure strain relief.  Ensure proper labeling

   b) Get correct length fiber for c1sus RFM and timing.

   c) Fix up final BO adapter box and DAC boxes.

   d) Make boxes for the AA filter adapters which are currently just hanging.

   e) Get two "faceplates" for the cards in the back of the ETMY IO chassis so they can screwed down properly.

   f) Remove and properly store old, unused cables, boards, and anything else.

6) Create new documentation detailing the current 40m setup, both DCC documents and interactive wiki.

7)  Setup an Ubuntu work station using Keith's wiki instructions

Simulated Plant To Do:

1)Create simulated plant to interface with current end mass controls (say scx).

2) Create proper filters for pendulum and noise generation, test suspension.

3) Propagate to all other suspensions.

4) Working on simulated IFO plant to connect to LSC.  Create filters for near locked (assume initial green control perhaps) state.

5) Test LSC controls on simulated IFO.

6) Fix c code so there's seamless switching between simulated and real controls.

CDS Status:

Here is a partial list of stuff which is being packed at LLO to be shipped to CIT.  The electronics ckt boards are yet to be added to this list.  Will do that tomorrow.

New Focus Servo Controller has just arrived. We have 25 days to evaluate this product.

It will have to be shipped back to the vendor on April 4, 2011 the latest in order to get full refund.

Just for a record. We got 4 new laser pointers (2 greens, 1 blue, and 1 green and red combination). Don't lose them.

They reside in a bucket on the SP table, where IR viewers and sensor cards also reside.

This is the grand plan we talked about in the beginning of the meeting.

• (Kiwamu) X-end Green cleaning up / Prep for DRMI
• (Bryan) Y-end Green
• (Suresh) Help Bryan / RF (w. Kevin)
• (Jenne) MC WFS / Y-arm IR alignment / MC adaptive feedforward (incl. CDS)
• (Koji) LSC
• (Joe) CDS cleaning up
• (Jamie) Help Joe / Noise Budget
• (Larisa) PMC scan / PSL photo&diagram
• (Barbarela) ASS

 *  Temporary strain relief for the heliax cables on 1X2 (Steve)

 *  RF diagrams and check lists (Suresh)

      => In the lunch meeting we will discuss the details about what we will do for the RF installation.

 *  Electronics design and plan for Green locking (Aidan / Kiwamu)

      => In the lunch meeting we will discuss the details.

 *  LSC model (Koji)

 *  Video cable session (team)

 * LPF for the laser temperature control (Larisa)

[Steve / Kiwamu]

 As a part of the video cable session, we reconnected some power cords on 1Y1 rack.

During the work we momentarily turned off c1aux, which handles DMF, Illumintators, mechanical shutters and the old video epics.

I think it automatically reverted the things, but we may need to check them.

I strain relieved RF cables labeled 33 MHZ LO and 166 MHZ to EOM at 1X2  This is a temporary setup for the 11 MHZ

The coax N  bulkheads connectors are mounted on the plastic front panel now.

 Low power green-red laser pointers are in. High power green, red and blue pointers are confiscated.

The ITMX/ITMY control swap is complete.

The steps from this elog were followed.

In addition, I did a burt restore of c1sus, c1mcs.

I then swapped all the gain settings from ITMX to ITMY, and reenabled the watchdogs.

I did some basic kick tests (1000 counts into UL coil) and confirmed channels like C1:SUS-ITMX_ULPD_VAR (watchdogs mV readback) corresponded to the correct optic.  I also checked that the POS, PIT, YAW, SIDE produced reasonable damping when engaged.

Problem:

Currently the c1scy, c1mcs, and c1rfm models are reporting an error with receiving some data sent over the GE Fanuc Reflected memory cards.

To be more exact, the C1:SUS-ETMY_ALS signal from the c1gcv FE code on the c1ioo computer going too the Y end is not being received.  However, the C1:SUS-ETMY_LSC signal is.  So the physical RFM card seems to be working.

Similarly, the TRY signal is being sent correctly from the Y end computer.  The X end is working fine and receiving both LSC and ALS signals.

The c1mcs and c1rfm models also receive data from the c1ioo computer and reporting receiving errors.

Theory:

Because the RFM cards are transmitting and receiving at least some channels, I'm guessing there was changes made to the C1.ipc file, which defines the memory locations of these various channels on the RFM network, and that when a model was rebuilt, a different one using the previous IPC file was not, and thus one of the computer is going to the wrong place to either read or write data.

Tomorrow, I'm planning on the  following:

1) Clean out the C1.ipc file (/opt/rtcds/caltech/c1/chans/ipc/)

2) Rebuild all models

3) Run activate_daq.py script

4) Restart models via script

If this doesn't clear up the problem, I'll continue  to bug hunt.

The attached plot shows 2 day trends of the PMC and MC reflected and transmitted power, the PSL POS/ANG QPD signals, and the temperature measured by the dust counter.

The power step in the middle of the plot corresponds to Koji/Jenne PMC realignment yesterday.

It looks like everything is following the day/night temperature changes.

Minicircuits ERA-5SM was used for the RF amp of the BBPD. This amp is promising as a replacement of Teledyne Cougar AP389
as ERA-5SM gave us the best performance so far among the BBPDs I have ever tested for the aLIGO BBPD/Green.

The -3dB bandwidth of ~200MHz and the noise floor at the shotnoise level of 0.7mA DC current were obtained.

1. Introduction

The aLIGO BBPD candidate (LIGO Document D1002969-v7) employs Teledyne Cougar AP389 as an RF amplifier.
This PD design utilizes the 50Ohm termination of the RF amp as a transimpedance resistance at RF freq.

However, it turned out that the bandwidth of the transimpedance gets rather low when we use AP389, as seen in the attachment2.
The amplifier itself is broadband upto 250MHz (the transfer function was confirmed with 50Ohm source).
The reason is not understood but AP389 seems dislike current source. Rich suggested use of S-parameter measurement
to construct better model of the curcuit.

On the other hand, the RF amplifiers from Minicircuits (coaxial type like ZFL-1000LN+), in general, exhibit better compatibility with PDs.
If you open the amplifier case, you find ERA or MAR type monolithic amplifiers are used.

So the question is if we can replace AP389 by any of ERA or MAR.

2. Requirement for the RF amp

- The large gain of the RF amp is preffered as far as the output does not get saturated.

- The amplifier should be low noise so that we can detect shot noise (~1mA).

- The freq range of the useful signal is from 9MHz to 160MHz.

The advanced LIGO BBPD is supposed to be able to receive 50mW of IR or 15mW of 532nm. This approximately corresponds to
5mA of DC photocurrent if we assume FFD-100 for the photodiode. At the best (or worst) case, this 5mA has 100% intensity modulation.
If this current is converted to the votage through the 50Ohm input termination of the RF amp, we receive -2dBm of RF signal at maximum.

This gives us a dilemma. if the amp is low noise but the maximum output power is small, we can not put large amount of light
on the PD. If the amp has a high max output power (and a high gain), but the amp is not low noise, the PD has narrow power range
where we can observe the shotnoise above the electronics noise.

What we need is powerful, high gain, and low noise RF amplifier!

Teledyne Cougar AP389 was almost an ideal candidate before it shows unideal behavior with the PD.
Among Minicircuits ERA and MAR series, ERA-5 (or ERA-5SM) is the most compatible amplifier.

Considering the difference of the gain, they are quite similar for our purpose. Both can handle upto -2dBm,
which is just the right amount for the possible maximum power we get from the 5mA of photocurrent.

3. Test circuit with ERA-5SM

A test circuit has been built (p.1 attachment #1) on a single sided prototype board. 

First, the transfer function was measured with FFD-100. With the bias 100V (max) the -3dB bandwidth of ~200MHz was observed.
This decreases down to 75MHz if the bias is 25V, which is the voltage supplied by the aLIGO BBPD circuit. The transimpedance
at the plateau was ~400Ohm.

Next, S3399 was tested with the circuit. With the bias 25V and 30V (max) the -3dB bandwidth of ~200MHz was obtained although
the responsivity of S3399 (i.e. A/W) at 1064nm is about factor of 2 smaller than that of FFD-100.

The noise levels were measured. There are many sprious peaks (possibly by unideal hand made board and insufficient power supply bypassing?).
Othewise, the floor level shows 0.7mA shotnoise level.

The RF amplifier of the prototype BBPD has been replaced from ERA-5SM to MAR-6SM.
The bandwidth is kept (~200MHz for S3399 with 30V_bias), and the noise level got better while the maximum handling power was reduced.

MAR-6SM is a monolithic amplifier from Minicircuits. It is similar to ERA-5SM but has lower noise
and the lower output power.

The noise floor corresponds to the shotnoise of the 0.4mA DC current.
Now the mess below 50MHz and between 90-110MHz should be cleaned up.
They are consistently present no matter how I change the PD/RF amp (ERA<->MAR)/bias voltage.
I should test the circuit with a different board and enhanced power/bias supply bypassing.

Discussion on the RF power (with M. Evans)

- Assume 5mA is the maximum RF (~50mW for 1064nm, ~15mW for 532nm). This is already plenty in terms of the amount of the light.

- 100% intenisty modulation for 5mA across 50Ohm induces -2dBm RF power input for the amplifier.

- Assume if we use MAR-6 for the preamplifier. The max input power is about -18dBm.
  This corresponds to 16% intensity modulation. It may be OK, if we have too strong intensity modulation, we can limit the power
  down to 0.8mA in the worst case. The shot noise will still be above the noise level.

- In the most of the applications, the RF power is rather small. (i.e. 40m green beat note would expected to be -31dBm on the RF amp input at the higherst, -50dBm in practice)
So probably we need more gain. If we can add 10-12dB more gain, that would be useful.

- What is the requirement for the power amplifier?

• Gain: 10~12dB
• Output (1dBcomp): +3dBm +Gain (13dBm~15dBm)
• Noise level / Noise Figure: 3nV/rtHz or NF=14dB
  The output of MAR-6 has the votage level of ~7nV/rtHz. If we bring the power amplifier with input noise of ~3nV/rtHz,
  we can surppress the degradation of the input equivalent noise to the level of 10%. This corresponds to N.F. of 14dB.

Search result for Freq Range 10-200MHz / Max Gain 14dB / Max NF 15dB / Min Power Out 13dBm
GVA-81 is available at the 40m. ERA-4SM, ERA-6SM, HELA-10D are available at Downs.

Conversion between nV/rtHz and NF (in the 50Ohm system)

SN1: Connect signal source (50Ohm output) to a 50Ohm load.
Power ratio between the noise and the signal

SN1 = (4 k T (R/2)) / (S/2)^2

SN2: Connect signal source (50Ohm output) to an RF amp.
Only the voltage noise was considered.

SN2 = (4 k T (R/2) + Vn^2) / (S/2)^2

10 Log10(SN2/SN1) = 10. Log10(1 + 2.42 (Vn / 1nVrtHz)^2)

e.g.
Vn: 0 nVrtHz ==> 0dB
Vn: 0.5 nVrtHz ==> 2dB
Vn: 1 nVrtHz ==> 5dB
Vn: 2 nVrtHz ==> 10dB
Vn: 3 nVrtHz ==> 13.5dB

BBPD update

- The BBPD circuit has been constructed on the aLIGO BBPD board

- It still keeps 200MHz BW with FDD-100 Si PD for the 100V bias.

- The noise spectrum has been cleaned up a lot more. It shows the noise level of the 0.4mA shotnoise between 9-85MHz.
The noise at 160MHz is the noise level of the 1mA shotnoise.

Some of the noise peaks at around 97MHz came from the bias voltage.

What to do next

- Confirmation of the performance with the original aLIGO BB PD configuration.

- Notch filter for 9MHz (for aLIGO).

- Implementation of a power amplifier. (issues: power supply and heat removal)

I found ITMX-ISCT and BS-ISCT ( IFO sensing-control table)  not covered this morning. Please do not leave tables open.

I have made my own AutoCAD WS account and put the latest 40m layout.
AutoCAD WS is a free cloud service which enable us to browse/edit the DWG files.

You can view/play/print it from the following link even without making the account.

https://www.autocadws.com/main/publish?link=RVFmNEtOd3EzNVFtRXcx

If you make your account you can actually save it although the editing capability is somewhat limited.

Notes:
- It needs the Flash plug-in and Internet connection.
- I think Safari is the most stable platform on Mac. (i.e. I had some malfunctions with Firefox and Chrome)

Here is the conclusive result for the circuit configuration for aLIGO BBPD and 40m Green PD.

- Use Mini-circuits MAR-6SM for the RF preamplifier. The 50Ohm input impedance is used for the RF transimpedance.
  The maximum output is ~4dBm.

- Use Mini-circuits GALI-6 for the RF middle power amp. The gain is 12dB and the amplifier is linear up to +17dBm. i.e. This is still linear at the maximum output level of MAR-6SM.

- The total RF transimpedance is ~2k. The DC transimpedance is also 2k.

- The bandwidth is 80MHz with FFD100 and internal 25V bias. When S3399 is used, the bandwdith goes up to 180MHz
although the responsivity of FFD100 at 1064nm is better than S3399 by a factor of 1.5. At the 40m we will use S3399 for the green BB PD.

- By adding an LC network next to the PD, one of the unnecessary signal can be notched out.
As an example, 9MHz notch was placed for the FFD100 case.

- Noise level: ~10pA/rtHz as a floor noise level at around 30MHz. This corresponds to the equivalent dark current of 0.4mA.

Matt has finished the PCB layout. We will order small first batches, and stuff it for the test. Some of these will be the 40m green PD.

[Jenne / Kiwamu]

We spent approximately an hour for the weekly Wednesday cleaning.

This time we moved onto an area where a desk and optics shelf reside along the Y arm.

We will continue cleaning up there in the next time too.

This is the new hot air station for the 40m lab.........

Kiwamu and I have started to put together a vent plan on the 40m wiki:

http://blue.ligo-wa.caltech.edu:8000/40m/vent/201107

We will keep working on this (there's still a *lot* to fill in), but please help fill in the plan by adding questions, answers, procedures, preparations, etc.

I put a paper Peet's bag with half of the Mini-Moos into George.

 Summary for the week ending June 26th.  (Number of elog entries = 53)

Photo diodes stored in the east arm cabinet E4:  ALL PDs  meet here, fast  or slow......

Summary of the week ending July 3rd.  Number of elog entries = 44 

- SUS

- LSC

- MC work

- CDS

- ABSL

- Fiber experiment

- TT characterization

- Configuration and other topics

Please ask the owner unless  it is rotten. Do not put food into garbage can inside. Take them outside so you are not inviting ants !

Each bottle has matched seals. They are not interchangeable.

It is critical that the solvent do not reach the rubber bulb. Practice with the pipet.

In case of solvent touching the suction bulb: do not let the solvent go back into the bottle! Remove bulb, let it dry out and rinse pipet.

It is essential that the solvent bottle must be rinsed and refilled if it's content met with the rubber bulb.

Use glass syringe with SS needle in critical application: Hamilton ~0.1 ml

Please return sensor card to  laser log box so others can use it. We have only one larger fluorescent sensor card.

 Summary of the week ending July 10th.  Number of elog entries = 21

- SUS

 + The cutoff frequency of the high pass filters for the damping were set to 30Hz.
 + Turned off all the BounceRoll filters.
 + The BS oplev was checked and seemed healthy.
 

- LSC

 + All the measred data of the LSC whitening filters were fit.
 + All the zpk parameters are recorded on the wiki.

- ABSL

+ The setup completed.  
 + The freqeucy-lock of the ABSL laser was achieved with UGF of ~ 40kHz.
 + The temperature of the ABSL laser was adjusted to be 47.25 deg
 

- ALS

 (Fiber experiment)
 + The I-P curve of the ETMY laser was measred.
 + The current set point is 1.8 [A], which used to be 1.5 [A], corresponding to the output of power of 197 [mW] and 390 [mW] respectively.
 

Summary of the week ending July 17th.  Number of elog entries = 20

Summary of the week ending July 24th.  Number of elog entries = 45

- LSC
 * Check of LSC WF switching
  -> some were switching, but the majority were not.

- SUS
 * Ran activateDQ.py for seeting some DQ channels of Oplevs
 * Turned ON all the offset buttons on the OL1, etc.
 * Rebuilt and restarted c1msc, c1sus, c1scx and c1scy as an update.
 * ETMY's shadow sensors look bad. Unknown noise below 3 Hz, which is higher than the usual floor by factor of 10.

- ABSL
 * The frequency lock was down.
 * The laser power into the RFPD had been too big, so it was reduced

- OAF
 * Seismometers were connected to the AA-board on 1X6
 * Most of the channels were acquired to the ADC, but some were not.

- Mode Cleaner
 * Gain of quadrants were checked.
 * Due to the SUS model update, the MC locking trigger hasn't worked correctly. This was fixed by changing ioo.db file

- Misc.
 * Virtual box was installed on Rossa. Altium is now available on Rossa.

The vent will start from 1 st of August ! !

 ++++ Task List for the vent preparation ++++

  + Preparation of beam dumps (Jamie / Steve)

  + Health check of shadow sensor and measurement of the cross-coupling  (Steve)

  + Measurement of the arm Lengths and estimation of the required precision (Kiwamu)

  + Alignment of the Y green beam (Suresh)

  + Alignment of the incident beam axis (Jenne)

  + Measurement of the MC spot positions  (Suresh)

  + Loss measurement of the arm cavities (Kiwamu / volunteers)

 ++++ Task List for the post-vent activity ++++

  + 3f RFPDs (Koji / Rana)

  + EOM resonant circuit (Kiwamu)  

  + Sophistication of the LSC model (Yoichi)

  + DRMI commissioning (Keiko / Anamaria)

Status update for the vent preparation:

The punchline is : We can not open the chamber on Monday !

##### Task List for the vent preparation #####

  (not yet) Low power MC

  (not yet) Measurement of the arm lengths

  (not yet) Alignment of the Y green beam (#5066)

  (not yet) Measurement of the MC spot positions

  (80% done) Estimation of the tolerance of the arm length (#5076)

  (done) Preparation of beam dumps (#5047)

  (done) Health check of shadow sensors and the OSEM damping gain adjustment (#5061)

  (done) Alignment of the incident beam axis (#5073)

  (done) Loss measurement of the arm cavities (#5077)

Summary of the week ending July 31st.  Number of elog entries = 53

- SUS
 + ETMY-LR sensor looked strange. Something wrong.
 + Responses from the DC alignment bias to the shadow sensors and the oplevs were checked.
   --> ETMY shows the response with the opposite sign. Wired.
 + ETMY shadow sensors were examined in terms of the spectra.
   --> WF, AA and ADC noise looks reasonably low and not high enough to explain the low frequency noise.
 + Adjusted all the OSEM gains

- LSC
 + MICH noise budget is ongoing. WF filter needs to be greater than 21 dB to have dark noise of the PD greater than ADC noise
 + The arms became lockable

- CDS
 + modified and re-ran activateDQ.py.
 + c1iscex crashed for unknown reasons and we physically rebooted it.

- ALS (Fiber experiments)
 + PMC trans is sampled for the fiber beat-note measurement on the PSL table.
 + The beat-note signal between PSL and X end laser were obtained.
 + Some optics in the ETMY table were rearragend to have the Y green light aligned.

- ACS / ASS
 + incident beam axis has changed a lot.
 + X arm and Y arm ASS were reactivated.
  ---> The sign of some of the control gains had been wrong.
 + The incident beam axis and X/Y arm were re-aligned

- IOO/MCWFS
 + Some medm screens fixed.
 + Adjustment of the demodulation phase on each quadrant on WFS1 and WFS2 are done.
 + The sensing matrix (from optics to WFS sensors) were measured.

- OAF
 + c1pem was modified
 + plugged a seismometers to ADC through an AA board.
   --> channels are coming to the digital land
 
- Preparation for the invac work
 + 7 pieces of beam traps are available
 + Tolerance of the arm length is estimated to be +/- 2 cm.


- PSL/RefCav
 + ABSL is injected into the reference cavity. some flashing happened but no locking.
 + eddited the psl.db file to set EGUF and EGUL
 + turned RefCav heater and servo back on

The vent will take place on Wednesday.

Plan for Tuesday :

  (Morning) Preparation of necessary items for the low power MC (Steve / Jamie)

  (Daytime) Measurement of the MC spot positions (Suresh)

  (Daytime) Arm length measurement (Jenne)

  (Nighttime) Locking of the low power MC (Kiwamu / Volunteers)

Plan for Wednesday :

  (Early morning) Final checks on the beam axis, all alignments and green light (Steve / Kiwamu / Volunteers )

  (Morning) Start the vent (Steve)

  (daytime-nighttime) Taking care of the Air/Nitrogen cylinders (Everybody !!)

Status of the vent preparation :

  (not yet) Low power MC

  (ongoing) Measurement of the arm lengths

  (ongoing) Measurement of the MC spot positions

  (80% done) Estimation of the tolerance of the arm length (#5076)

  (done) Alignment of the Y green beam (#5084)

  (done) Preparation of beam dumps (#5047)

  (done) Health check of shadow sensors and the OSEM damping gain adjustment (#5061)

  (done) Alignment of the incident beam axis (#5073)

  (done) Loss measurement of the arm cavities (#5077)

I have updated the 40m public calender.

Main change :

  + The vent starts from 3rd of August

  + Keiko and Anamaria (LSU) come from 13th of August

Tomorrow's main goal is : let the both X and Y green light come out from the chambers.

Plan of the in-vac work for tomorrow :

    - Removal of the access connector and the BS north door, starting from 9:00 AM. (requires 6 people)

   - If necessary, align ITMs and ETMs to get the green light nicely flashing / locked.

   - Take pictures of the BS and IOO table before installing / repositioning some optics.

   - Repositioning of the green periscope in the BS chamber to let the Y green light go through it.

   - Steer some green mirrors on the IOO table to let the Y green light come out from the chamber.

   - Steer some green mirrors on the BS table to let the X green light come out from the chamber.

   - Put some beam traps on the BS table

   - Leveling of the BS table. (Do we need to level the IOO table ? it will change the spot positions on the MC mirrors somewhat)

   - Take pictures again.

   - Extra jobs : if we still have some more times, lock MC and check the beam clearance at the Faraday. Also check some possible beam clippings for the IR beam.

   - Close the chamber with the light doors.

   - Softball game at 6:30 PM.

[Jamie, Jenne, Suresh, Steve, Koji, Kiwamu]

We got two green beams coming out from the chambers !

Summary of today's invac work :

    - removed the access connector and the BS north door

    - realigned the X and Y arm to the green beams.

    - installed a HWP on the ETMY table to rotate the polarization of the green beam to P.

    - repositioned the first periscope on the BS table.

    - repositioned the second periscope on the IOO table.

    - steered some green mirrors on the IOO and OMC chamber to let the Y green beam come out to the PSL table.

    - installed a PBS in front of the first periscope to spatially overwrap two green beams.

    - adjusted the incident angle of the PBS to maximize the power of the Y green beam, which is transmitted through it.

   - steer two mirrors on the BS table to align the X green beam

   - installed two beam dumps, one is near the PBS to eliminate a ghost in the X green beam, and the other is on the back side of IPPOS/ANG pick off window.

   - closed the doors.

Some Notes:

 When steering the final green mirror on the OMC table, accidentally we changed the alignment of the MC incident mirror.

So the alignment of the incident beam going into MC has changed, and we haven't re-aligned it yet.

 During we were installing the PBS on the BS table, we found that the allowable incident angle for the Y beam is about ~ 55 deg, which maximizes the amount of the transmitted Y green.

Since the PBS had been considered to be 45 deg incident in our optical layout, this required several modifications in the green mirrors.

To have a clear X green beam path going into the PBS, we had to slide the PBS and periscope to the West.

The periscope is now sitting on the very edge of the BS table, and in fact ~ 20% of the bottom plate of the periscope is already sticking out.

Also since 30% of the area of the PBS's post is on a hole, which is somehow for the stack, we had to use three dog clamps instead of a folk clamps to make the contact tight.

Today's main mission is : adjustment of the arm length

   + Open the ETMX(Y) door, starting from 9:00 AM

   + Secure the ETMX(Y) test mass by tightening the earthquake stops.

   + Move the ETMX(Y) suspension closer to the door side

   + Inspect the OSEMs and take pictures before and after touching the OSEMs.

   + Level the table

   + Adjust the OSEM positions

   + Move the ETMX(Y) suspension to have designed X(Y)arm length

   + Level the table again

   + Align the ETMX(Y) such that the green beam resonate

The horizontal trolley drive stopped working  at the east end this morning. It is working intermittently. In the worst case we can take the door off with the manual -Genie- lift.

I'm working with Konecrane to solve  the wormgear drive problem.

[Jamie, Suresh, Jenne, Koji, Kiwamu]

After this morning's hiccup with the east end crane, we decided to go ahead with work on ETMX.

Took pictures of the OSEM assemblies, we laid down rails to mark expected new position of the suspension base.

Removed two steering mirrors and a windmill that were on the table but where not being used at all.

Clamped the test mass and moved the suspension to the edge of the table so that we could more easily work on repositioning the OSEMs.  Then leveled the table and released the TM.

Rotated each OSEM so that the parallel LED/PD holder plates were oriented in the vertical direction.  We did this in the hopes that this orientation would minimize SD -> POS coupling.

For each OSEM, we moved it through it's full range, as read out by the C1:SUS-ETMX_{UL,UR,LL,LR,SD}PDMon channels, and attempted to adjust the positions so that the read out was in the center of the range (the measured ranges, mid values, and ultimate positions will be noted in a follow-up post).  Once we were satisfied that all the OSEMs were in good positions, we photographed them all (pictures also to follow).

Re-clamped the TM and moved it into it's final position, using the rails as reference and a ruler to measure as precisely as possible :

ETMX position change: -0.2056 m = -20.56 cm = -8.09 in (away from vertex)

Rebalanced the table.

Repositioned the mirror for the ETMX face camera.

Released TM clamps.

Rechecked OSEM centering.

Unblocked the green beam, only to find that it was displaced horizontally on the test mass about half an inch to the west (-y).  Koji determined that this was because the green beam is incident on the TM at an angle due to the TM wedge.  This presents a problem, since the green beam can no longer be used as a reference for the arm cavity.  After some discussion we decided to go with the TM position as is, and to realign the green beam to the new position and relock the green beam to the new cavity.  We should be able to use the spot position of the green beam exiting the vacuum at the PSL table as the new reference.  If the green X beam exiting at the PSL table is severely displaced, we may decide to go back in and move ETMX to tweak the cavity alignment.

At this point we decided that we were done for the day.  Before closing up, we put a piece of foil with a hole in it in front of the the TM face, to use as an alignment aperture when Kiwamu does the green alignment.

Kiwamu will work on the green alignment over the weekend.  Assuming everything works out, we'll try the same procedure on ETMY on Monday.

The table below gives the OSEM positions as seen on the slow chanels C1:SUS-ETMX_{UL,UR,LL,LR,SD}PDMon

Note that the side OSEM has the fast channel (OUTPUT) available and we used that to locate it.

When we began work the OSEMs were photographed so that we have a record of their locations till now.  It was difficult to get accurate estimate of the magnet offset inside the OSEM we could not see the screen on the camera while clicking.  We then took some pictures after finishing the work. These are given below

The picture of the left is from before OSEMs were moved. It can be seen that OSEMs are rotated to make sure that the magnets avoid touching the teflon sheets which hold the shadow sensors.  The picture on the right shows the positions of the OSEMs after we adjusted their positions.  This time we kept the teflon sheets vertical as shown to minimise the coupling between the Side and Axial directions.

We needed to reposition them once again after we moved the tower to the center of the table.

Pictures with more detail will be posted to the wiki later.