Ground Loop hunting - another in-vac cable grounding culprit to look for from R. Abbott

From R. Abbott's log in LLO's alog:

Ok, this sort of thing is hard to describe, but I'll try:

1.  I assume the problem you are describing is associated with the flange end vacuum side cable interface
2.  This PEEK body of this type of connector is held together by several screws that are only visible with the connector unplugged from the flange
3.  The body screws I just mentioned thread directly into the metal backshell.  Here's the point of badness.
4.  If the heads of the screws stick out whatsoever, they will contact the inside metal surface of the vacuum flange.  This is probably where you are getting your grounding problem.

As for the OSEM ground, armed with the understanding of loose screws and grounding problems, I would look carefully for a similar mechanism.

See his full log in response to ground hunting at LLO:
https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=9810

Burt backup scripts fixed again...

The environment was still not correct for the burt scripts.  Fixed, the latest one run automatically appears to have worked.

Replaced Sus Ham-A Coil Drivers

Replaced the Ham-A Coil Drivers in SUS C4 (U7, U8, U13, U14) with ones modified as requested in E1201027.

These are the HAM-A Drivers for the HAUX; 
Optic Name       Name on Drawing*       Rack Location      Chassis Serial Number
    IM1                SM1                C4 - U14                S1201156 
    IM2               PMMT1               C4 - U8                 S1201162
    IM3               PMMT2               C4 - U7                 S1201155
    IM4                SM2                C4 - U13                S1201165

* aLIGO SUS HAM2 System Wiring Diagrams, Current Version, D0902810-v7

This means that the output impedance for these drivers is significantly less that before, which means both the noise and the drive strength have decreased by a factor of a factor of 10 (calculation below). This explains why we need much more drive from the IM's DAC in order to retain the same alignment offsets (see LHO aLOG 8759), and as Cheryl mentions, in some cases (IM3), the DAC saturates before we can get to the desired alignment offset. So, we either need to physically offload the alignment on the SUS themselves or reduce the output resistors enough to be able to both obtain the desired alignment while still meeting the noise reduction goal.

(Icoil / Vin)_after      (Vin/Vout)_after / (Rcoil + 2*Rout_after )
-------------        =   ----------------------------------------- 
(Icoil / Vin)_before    (Vin/Vout)_before / (Rcoil + 2*Rout_before )

                        (Rcoil + 2*Rout_before)
                     =  ------------------------
                        (Rcoil + 2*Rout_after)

                        (Rcoil.aosem = 19.8 [Ohm] [see LLO aLOG 3340])
                        (Rout_before = 100 [Ohm])
                        (Rout_after  = 1200 [Ohm]

(Icoil / Vin)_after      
-------------        =  0.098
(Icoil / Vin)_before

Ref Cav power budget, AOM alignment

Stefan, Sheila

This morning Stefan and I returned to the PSL.  First we adjusted the AOM alingment to improve the diffraction efficency.  In the end we measured (with the filter on the power meter) 

33mW before AOM 
27.4mW after (single pass)
24.35mW after double pass

at around 74% double pass efficency, this is pretty good now.  Stefan adjusted the efficiency of the first pass by moving the AOM (mostly in pitch) and the second pass efficiency by aligning the retro reflecting mirror.  

After this the beam looked low in the apperatures of the EOM, so we moved it down, effectively undoing what Kiwamu and I did yesterday to keep the beam centered in the apperatures.  Once we had realinged the ref cav, the beam spot on the reflected camera was again in approximately the center, but now the beam spot clearly has 2 lobes when the cavity is unlocked.  Stefan removed the ND filter on the camera to make sure this wasn't an artifact, and the lobed shape remained.  

We then double checked the ref cav power budget, now making all measurements with the filter off:

23mW incident
refl (after PBS for circulator) 21.1mW (130mV on refl PD when unlocked)
locked cavity refl PD 29mV (this means 4.7mW refl unlocked)
the dark offset on this PD is 0.8mV (measured yesterday)
transmitted: 12.2mW (trans PD voltage 1.21V)

This is a visibility of 78%, but we are still lossing 25% of the power, as we were yesterday.  

We found one gost beam, which seems to be coming from the veiwport.  This light gets onto the refl PD, and causes an offset of about 1.6mV, not really significant in our power budget.

Once we were done I moved the razor blade dump that is behind the retroreflecting mirror for the AOM back about an inch so that there was room to add an iris on the leakage beam through that AOM.  
Cheryl suggested this as a way of monitoring if the beam position there drifts.  I left the iris opened so that the beam is normally dumped on the razor blade, but when the iris is closed the beam 
is right on the center. 

I also looked with the beam leveler (the aluminum one inside the PSL that Doug Cook had made, with lines scribed on it and small pin holes.)  
The path between the PMC and the ref cav is consistently silghtly below 4 inches on that leveler, but this is probably just because a different reference was used when leveling the beam. 

HSTS TFs comparison

[Jeff K Arnaud P]

Following the DTT round of transfer functions ran during monday on the 5 HSTS suspensions of HAM2 and HAM3 chambers, we processed the data today, and the results are plotted in the attached doc. Those measurements have been taken after the optics were cleaned up and the doors were put on. ISIs were damped, HAM3 HEPI unlocked, HAM2 HEPI locked. The first attachment shows a comparison between MC1 MC2 MC3 PRM PR2 of LHO and MC3 of LLO. The second attachement is a zoomed version of the first between 0.1 and 10Hz.

Most of the results look very good and consistent with the model, and there are only a few things to notice :

* MC1 and MC3 have an extra resonance at 0.85Hz in the roll DOF which corresponds to the first vertical mode. This feature will certainly disappear with the vertical DOF damped (to try)

* MC2 has successive poles (1.516Hz and 2.07Hz) and successive zeros (1Hz and 1.094Hz) in the L DOF, which is not something we are used to see in our TFs with collocated actuation and sensing. Though, the feature is very small, and shouldn't raise concerns.

~0800 thru 1800 hrs. local -> continued "attended" pump down of HAM1,2,BSC1,2,3,7 combined volumes

Kyle 

Should be on Turbo at some point tomorrow 

Soft-cycled GV19 for Apollo to connect spool to GV20

Kyle

~0800 hrs. local - > Shut down LVEA purge air supply for service

Gerardo 

Replacing (4) each OE check valves

Repaired Burt Backup scripts

Added a line to source the epics-user-env.sh file for the proper version of epics in the burt backup scripts running on script0.  The environment was incorrect and the burt backup was failing.

SEI status

Here is the current status of the aLIGO SEI work at Hanford. The main updates of this week are:

- ITMX, HAM2 and HAM3 have been tested (chambers are closed)

- HEPI generic and local models have been updated, installed and tested

 

·         BSC1 - ITMY

o    ISI + HEPI - Unlocked, Previously commissioned.

·         BSC2 - BS

o    ISI + HEPI - Unlocked, Previously commissioned.
 

·         BSC3 - ITMX

o    ISI : Testing complete, in chamber. Report validated.

o    HEPI : Unlocked.

 

·         BSC9 - ETMX

o    ISI : Unlocked. Testing complete.       

o    HEPI : Unlocked, ongoing initial alignment.

         HAM 1

o    HEPI: Locked and vented.
      Low priority testing 

·         HAM2

o   ISI: previously commissioned with HEPI locked, currently unlocked, in vacuum

o   HEPI - IPS position loops and alignment offsets installed
     Locked

·         HAM 3

o   ISI: previously commissioned with HEPI locked, currently unlocked, in vacuum

o   HEPI - IPS position loops and alignment offsets installed
     Unlocked

·         HAM 4 

o   ISI: In chamber, Previously tested during assembly validation, currently locked, no suspension installed, in-vac cables not connected.
     Electronics ready, in field cables ready, in-rack cables ready. Temporary STS cables
     Model is running, and MEDM screens are available in the Sitemap.

o   HEPI: Currently locked, to be commissioned
     Electronics ready, in field cables ready, in-rack cables ready. Temporary STS cables
     Model is running, and MEDM screens are available in the Sitemap.

·         HAM 5

o   ISI: In Chamber, Previously tested during assembly validation, currently locked, no suspension installed, in-vac cables not connected,
     Chamber temporarily closed.         
     Electronics ready, in field cables ready, in-rack cables ready. Temporary STS cables
     Model is running, and MEDM screens are available in the Sitemap.

o   HEPI: Currently locked, to be commissioned     
     Electronics ready, in field cables ready, in-rack cables ready. Temporary STS cables
     Model is running, and MEDM screens are available in the Sitemap.

·         HAM 6

o   ISI: 
     in chamber.
     Unlocked, no SUS
     Mechanical adjustments complete
     Initial in-chamber testing complete, but not validated yet

o   HEPI: Locked

 

Tagged and moved to tested dust monitor code

This falls under WP 4303.

The dust monitor code tested under WP 4287 survived the weekend. The difference seems to be running it with 'procServ' instead of 'screen'.

I made tagged releases of the tested code and updated the target directories in /ligo/lho/h0/target. The support module was tagged as met_one_227b_comp_ctrl-1.2.0 and the IOC directory was tagged as dust_met_one_227b_comp_ctrl-1.2.0. I changed the startup scripts in the target directories to use 'procServ'.

I restarted the IOCs from the target directories on h0epics.

OPS Summary

- EX feadthrough work

- dust monitor code change

- close GV19

- install spool X in LVEA

- reinstall cryopump EX

- test stand reinstall/level EY

- X arm spool oplev piers - drilled anchor bolts

- replace  SUS and ISC HAM-A coil drivers, which are actually IO optics

- pull cables HAM6 to electronics room

IM (aka HAM AUX, HAM-A, HAUX...) coil driver change

Coil drivers were changed for IM1, IM2, IM3, IM4, and all offsets required changes.  This was complicated by choosing to do this change on the day we started pumping down the vertex, i.e. optics are moving due to pumpdown - choose comparisson times wisely.  Spreadsheet attached shows times used and old and new offsets.

For more details, see LHO aLOG 8767.

Viewport Cover for TCS

Tyler G. Greg G.
Fabbed up some sheet metal covers for the BSC 1 and 3 viewports. These were installed to make the viewports compliant with our laser safe standards. They don't have warning labels on them saying not to be removed, so try and avoid removing them.

SUS Closeout Measurements -- PR3 and ITMX Look Good. Yellow Flags but no Show Stoppers

J. Kissel

I've gathered full sets of close out transfer functions for H1SUSPR3 (and HLTS) and H1SUSITMX (a wire-suspended QUAD). The results look good enough to proceed with pump down!

Yellow Flags:
H1SUSPR3 -- The Q of the 1st first vertical mode appears to be reduced from previous measurements of the free in-air suspension. I attach the .pdf of the raw DTT results for this DOF as well, to show that the coherence is still good for this resonance, implying a real loss mechanism. This is also noticeable on the R and T degrees of freedom as well, again only on the first resonance. But all resonant frequencies are in the same place, so the dynamics are as expected and well-behaved. In the end, we want these modes damped anyways, right? However if it is a real source of loss, then it's a source of noise. However, given that these are all the lowest frequency resonance, and it's the V/R DOFs it means that the loss is most likely on the top blade springs -- well away from the optic, so what ever excess noise is present will be filtered by the otherwise free SUS.

H1SUSITMX -- The only thing awry here is that the R0 V and R DOFs show much higher response (an overall DC scale factor) than expected. However, it was immediately obvious that this is a result of calibration filters not turned on. Taking a look, we immediately discovered this to be the case -- the "to_um" filters has been turned off for ONLY the R0 LF and RT OSEMs. They're now turned on, and we will be sure to capture a new safe.snap so this problem doesn't arise again.


All data and common scripts (with updated meas:ists) are committed to the SusSVN as of this entry.

H1-ITMx BSC3 Mechanical Closeout - backlogged alog

This alog should be filed on last Thursday's date. 

Last Thur, Calum and I cleaned the ITMx suspension and BSC chamber surfaces (IPA and wipes).  We pulled the First Contact on the CP-AR, ITMx-HR, and the little 1" witness plate attached to the structure.  (We had reinforced the FC the day before, via painting over the ITMx-HR windows and spray-cone-ing the CP window.)  We then checked a few DOF TFs on the ITMx and exited.  The West door was promptly put on.

Inspection in HAM2:

Jodi and I inspected HAM2 withness plates and surfaces, and found a lot of articulate.  Wafers also have visible finger prints, that I put there installing them - good reason to use our nifty wafer tweezers.  Particulate found on all wafers.  Examples include but are not limited to white fibers, black flecks, white flecks, metal flecks, bright red stuff, and a bit of First Contact.

- Jodi, Cheryl

Observations of witness plates and other in-chamber surfaces goes as follows:

Every surface we looked at had particulate, including table top, optic structures, etc.  Optics, both small fixed 2" and the larger 4" IM2 and IM4, show particulate.

Witness Plates:

- Worst contamination: 
One 4" witness plate on the HAM2 table top:
Exposed during IO installation, pump down and vent.  
Significant particulate, and my gloved hand print.

- Competing for the next worst contamination:
Two 4" witness plates in the beam tube, North and South of HAM2:
Exposed during pump down and vent.  
Large particulate easily seen from about 1.5m away.

Two 4" witness plates in the bottom of HAM2:
Exposed during pump down and vent.  
Large particulate easily seen from about 1.5m away.

- The winners, showing the least contamination:
4" witness plates in the beam tube, West side of HAM2 on ISI level-0, positioned North, Center, and South:
Exposed during pump down and vent.  
Small particulate easily seen by eye.

- The three 1 optics had some particulate but were very hard to evaluate in-chamber, so hard to say how much contamination is on their surfaces until we can pick them up.  There was a piece of First Contact, about 1mm square, on one of the 3 optics - it was missed by at least two sets of eyes before pump down.  The up-side is that this does show that FC stayed put on an optic during pump down and venting.

Current State of Witness Plates in HAM2:
We did not have containers to remove wafers or 1" optics, so new wafers were installed along side the old wafers, (in every position, the new wafer is installed in the counter-clockwise direction from the old wafer).  Two new wafers replaced the old table top wafer, and the old wafer was moved across the table, to prevent it from contaminating the new wafers.

HAM2 witness plates: Installed Dec. 19, 2012

Attached are pictures of witness plates I installed in HAM2 before pumpdown.  There are 4" silicon wafers and 1" optics in the chamber, and most are on stage-0 of the ISI or in the beam tube, one 4" wafer is on the HAM2 table surface, near the North edge of the table.

#62 = NW corner of stage-0, showing three 1" optics and one 4" silicon wafer
#63 = beam tube North of HAM2 ISI, showing one 4" silicon wafer
#67 = W side of stage-0, showing one 4" silicon wafer
#70 = beam tube South of HAM2 ISI, showing one 4" silicon wafer
#71 = SW corner of stage-0, showing one 4" silicon wafer
#74 = HAM2 floor, under stage-0, showing two 4" silicon wafers

Not shown, one 4" wafer on the HAM2 table.


- Total number of 1" optics in chamber = 3.

- Total number of 4" wafers in chamber = 8.

Dec. 19th alog link:
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=5047