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ID Date Authorup Type Category Subject
  2825   Wed Apr 21 15:53:57 2010 JenneUpdatePEMSeismometers now on the granite slab

The 3 seismometers are now on the granite slab.  The Ranger is now aligned with the Xarm (perpendicular to the Mode Cleaner) since that's the only way all 3 would fit on the slab.

Attachment 1: P4210048.JPG
  2833   Thu Apr 22 20:28:40 2010 JenneUpdatePEMSeismometer Noise Characteristics

Quote from elog 2237, 11 Nov 2009:

The attached plot shows the spectra of the 3 Z axes of the 3 seismometers we have (this data is from ~20Aug2009, when the Ranger was in the Z orientation) in Magenta, Cyan and Green, and the noise of each of the sensors in Red, Blue and Black.  The noise curves were extracted from the spectra using the Huddle Test / 3 Corner Hat method.  The Blue and Black traces which are just a few points are estimates of the noise from other spectra.  The Blue points come from the Guralp Spec Sheet, and the Black comes from the noise test that Rana and I did the other day with the Ranger (elog 2223).  

I'm not really happy with the black spectra - it looks way too high.  I'm still investigating to see if this is a problem with my calibration/method....

 So, as it turns out (surprise), I'm a spaz and forgot a 2*pi when calibrating the Guralp noise spectra from the spec sheet.  I noticed this when redoing the Huddle Test, and comparing my Spec Sheet Guralp noise with Rana's, which he shows in elog 2689.  When going from m/s^2, the units in the spec sheet, I just tilted the line by a factor of frequency.  Koji pointed out that I needed a factor of 2*pi*f.  That moves the Guralp spec line in the plot in elog 2237 (to which this entry is a reply) down by ~6, so that my measured noise is not, in fact, below the spec.  This makes things much more right with the world.

In other news, I redid the Huddle analysis of the 2 Guralp seismometers, ala Rana's elog 2689. The difference is now we are on the granite slab, with soft rubber feet between the floor and the granite.  We have not yet cut holes in the linoleum (which we'll do so that we're sitting directly on the 40m's slab).

Rana> this seems horrible. Its like there's a monster in there at 6-7 Hz! Either the seismos are not centered or the rubber balls are bad or Steve is dancing on the granite slab again.


Attachment 1: Gur1_Gur2_noise.png
  2889   Thu May 6 18:25:20 2010 JenneUpdatePEMAcc power supply turned on

The accelerometer power supply / preamp board has been OFF because of exciting new accelerometer measurements.  It's now on, so watch out and make sure to turn it back off before plugging / unplugging accelerometers.

  2892   Thu May 6 19:51:22 2010 JenneUpdatePEMNew 'Seismic Spectrum of the 40m'

For reasons unknown, the seismic spectra posted above Rosalba has been wrong since ~January when it was first posted.  The noise that we were claiming was waaaay lower than is really possible.

Rana and I checked the calibrations, and the numbers in DTT for the Ranger and the Guralp are correct (it's unknown what was being used at the time of the bad plot) - Cal for the Guralp is 3.8e-9 m/s, and for the Ranger is 1.77e-9 m/s.

Something is funny with the accelerometer calibration.  Hopefully Kevin's investigation will sort it out.  Their calibration used to be 1.2e-7 m/s^2 , but it was changed to be 7e-7 m/s^2 to match the noise level of the accelerometers with the seismometers at ~10Hz. We need to go through the calibration carefully and figure out why this is!

Posted above Rosalba for easy reference, and attached below, is the new seismic spectra.  The black trace is when the Ranger's mass is locked down, and the teal circle markers indicate the Guralp Spec-Sheet Noise Floor.

** Rana says> the y-axis in Jenne's plot is (m/s)/sqrt(Hz). The Guralp has a velocity readout bandwidth of 0.03-40 Hz, so we would have to modify the calibration to make it right in those frequencies. I believe the Ranger cal has the correct poles in it. The huge rise at low frequencies is because of the 1/f noise of the SR560.

Attachment 1: SeisRef_6May2010_AccelCalFudged.png
  2934   Fri May 14 16:19:22 2010 JenneUpdatePEMGuts of a Guralp

[Jenne, Rana]

We took apart and examined one of the Guralp seismometers this afternoon.  For the most part we think we understand how it works. The horizontal sensors are a little more confusing, since we didn't end up finding the moving masses.  The vertical sensor is a flat rectangle, hinged at one edge.  There are capacitive sensors above and below the rectangle.  The hinged end is connected to a leaf spring. 

The PCBs are packed full of old-school 80's components.  We probably need an actual schematic to figure out where the preamp circuit is, which is what we'd want to think about fitzing with, if we were to try to improve the noise of the seismometer.  For now, we put it all back together, and back out on the granite slab. 

There was a wee bit of confusion when putting the N/S marker-spikes back on as to where they should go.  The solution is that the handle of the seismometer is aligned with the North/South axis, so the spikes should be aligned with the handle.  The lid of the seismometer is uniquely aligned to the stuff inside by the ribbon cable connector, as well as the holes in the lid for accessing the centering potentiometers.  So, align the lid to the pots, and then align the spikes to the handle.

Photos are on Picasa.

  2941   Mon May 17 19:42:11 2010 JenneUpdateIOOFirst steps toward MC mode measuring

[Jenne, Kevin, Steve]

We made some progress toward getting the MC's beam profile measured.  In the end, no changes were made to anything today, but we're more prepared to go for tomorrow.

What we did:

* Grabbed the scanning slit beam scan from the PSL lab.  It's the same kind as we had here at the 40m, so Kevin was able to hook it up to the computer, and confirmed that it works.

* Opened the IOO and OMC chamber doors, and locked the MC.  Unfortunately the MC mode was awful in Yaw.  Awful like TEM(0,10+). But it still locked.  

* Confirmed that the beam went through the Faraday.  I looked at the beam before and after the Faraday on a card, and it was the same nasty beam both before and after.  So it looks like Zach did a good job aligning the Faraday and everything else.  I was going to clamp the Faraday, but I didn't yet, since I wanted to see the nice happy TEM00 mode go through without clipping before risking moving the Faraday during clamping (I don't know how heavy it is, so I'm not sure how much it might potentially move during clamping.)

* Noticed that there is a whole lot of crap on both the OMC and BS tables that's going to have to move.  In particular, one of the weights leveling the OMC table is right where I need to put MMT2.  Steve suggested putting the optic there, in its approximate place, before doing too much other stuff, since it could potentially affect the leveling of the table, and thus the input pointing to the MC.  Unfortunately, to do that I'll need to move the weight, which is definitely going to change things.  Sad face.  Moving the weight will likely be one of the first things I do tomorrow, so that all 3 profile measurements have the same configuration. 

* Before closing up, I tried to align the MC, to get back to TEM00, to no avail.  I got as far as achieving TEM11 flashing, along with a bunch of other crappy modes, but didn't get 00.  That's also on the to-do list.

What we're going to do:

* Open the chambers, and align the MC to TEM00 (using the sliders on the MC align screen).

* Check with an IR card that the beam goes through the Faraday.

* Clamp the Faraday, reconfirm.

* Remove the weight on the OMC table.

* Place MMT2 on the OMC table in it's approximate final location.

* Realign the MC, and make sure the beam goes through the Faraday.  If this doesn't happen smoothly, I may need more instruction since I've never dealt with aligning the Faraday before.  What are the appropriate mirrors to adjust? 

* Move the PZT flat steering mirror from the BS table to the IOO table.  (Thoughts on this?  This will change the table leveling, and also includes the trickiness of needing to move the connectors for the PZT.)

* Place a flat mirror on the BS table to route the MC beam out to the BS/PRM/SRM oplev table. 

* Measure the mode using the beam scan: on the BS oplev table, on the POX table, and then perhaps by shooting the beam through the beamtube on the ETMY (new convention) table.

* Place MMT1 on the BS table, use flat mirrors to get it out of the chambers, repeat measurements.

* Place MMT2 in the correct position, use flat mirrors to get it out of the chambers, repeat measurements.

All of this may require some serious cleaning-up of the BS table, which is going to be ugly, but it has to happen sometime. Hopefully I can get away with only moving a minimal number of things, in order to get these measurements done.


Another note: Don't trust the PSL shutter and the switch on the MEDM screens! Always use a manual block in addition!!! We discovered upon closeup that hitting the "Closed" button, while it reads back as if the shutter is closed (with the red box around the buttons), does not in fact close the shutter.  The shutter is still wide open.  This must be fixed.

  2950   Tue May 18 23:03:08 2010 JenneUpdateIOONo real progress....

[Jenne, Kevin]

No real progress today.  We opened the chambers and again tried to lock the MC.  Gave up after ~2.5 hours (and closed up the chambers with light doors, replaced manual beam block, etc...).  With Koji's helpful coaching, hopefully we'll finally get it done tomorrow.  Then we can move forward with the actual to-do list. 


  2952   Wed May 19 16:00:18 2010 JenneUpdateIOOHooray! We locked the MC! (and some other stuff)

[Jenne, Kevin]

We opened up the MC chambers again, and successfully got the MC locked today!  Hooray!  This meant that we could start doing other stuff....

First, we clamped the Faraday.  I used the dog clamps that Zach left wrapped in foil on the clean cart.  I checked with a card, and we were still getting the 00 mode through, and I couldn't see any clipping.  2 thumbs up to that.

Then we removed the weight that was on the OMC table, in the way of where MMT2 needs to go.  We checked the alignment of the MC, and it still locks on TEM00, but the spot looks pretty high on MC2 (looking at the TV view). We're going to have to relevel the table when we've got the MMT2 optic in the correct place.

We were going to start moving the PZT steering mirror from the BS table to the IOO table, place MMT2 on the OMC table, and put in a flat mirror on the BS table to get the beam out to the BS oplev table, but Steve kicked us out of the chambers because the particle count got crazy high.  It was ~25,000 which is way too high to be working in the chambers (according to Steve).  So we closed up for the day, and we'll carry on tomorrow. 


Photos of the weight before we removed it from the OMC table, and a few pictures of the PZT connectors are on Picasa

  2961   Thu May 20 20:03:37 2010 JenneUpdateSAFETYDon't walk down the Y(new convention) arm tonight!

Please don't go down the Yarm (Old Xarm) for right now, or if you do, please be very careful.  Kiwamu and I are set up to take beam scan measurements down the walkway, and so there are some cables / carts / other stuff down there.  We are going to get dinner really quickly before beginning the measurements. 

Right now, the PSL shutter is Closed, so there is no beam hazard outside of the chambers, just crowded space hazard.

  2962   Fri May 21 00:21:24 2010 JenneUpdateSAFETYDon't walk down the Y(new convention) arm tonight!

All clear.


Please don't go down the Yarm (Old Xarm) for right now, or if you do, please be very careful.  Kiwamu and I are set up to take beam scan measurements down the walkway, and so there are some cables / carts / other stuff down there.  We are going to get dinner really quickly before beginning the measurements. 

Right now, the PSL shutter is Closed, so there is no beam hazard outside of the chambers, just crowded space hazard.


  2963   Fri May 21 00:30:44 2010 JenneUpdateVACTP3 fore pump is very loud

[Jenne, Kiwamu, and Steve via phone]

Around 9:30pm, Kiwamu and I came back from dinner, and were getting ready to begin the beam scan measurements.  I noticed that one of the vacuum pumps was being very loud.  Kiwamu noted that it is the fore pump for TP3's turbo, which he and Steve replaced in January (elog 2538).  We had not noticed these noises before leaving for dinner, around 8pm.

We called Steve at home, and he could hear the noise through the phone. He said that even though it was really loud, since it was reading 3.3mTorr (on the display of the controller, in the vacuum rack just above head-height) which is close to the nominal value, it should be fine to leave.  He will check it out in the morning.  If it had been reading at or above ~1Torr, that's indicative of it being really bad, and we would have needed to shut it off.

For future reference, in case we need to turn it off, Steve said to use the following procedure:

1. Close VM3, to isolate the RGA, which is what this pump is currently (while we're at atmosphere) pumping on.  I don't know if there are other things which would need to be shut at this stage, if we were at vacuum nominal.

2. Close VM5, which is right in front of TP3, so TP3's pump is just pumping on itself.

3. Push the "Stop" button on the Turbo controller for TP3, in the vacuum rack, about waist level.  Turning off the turbo will also turn off the fore pump.

UPDATE, 1am: The controller in the rack is reading 3.1mTorr, so the pump, while still noisy, still seems to be working.

  2964   Fri May 21 00:51:06 2010 JenneUpdateIOOFirst MC mode measuring (hopefully) done

[Jenne, Kiwamu, Steve]

Round 1 of measuring the MC mode is pretty much done.  Yay.

Earlier today, Steve and I launched the MC beam off the flat mirror just after the Faraday, and sent it down toward ETMY(new convention). We ended up not being able to see it all the way at the ETM because we were hitting the beam tube, but at the ITM chamber we could see that the beam looked nice and circle-y, so wasn't being clipped in the Faraday or anywhere else.  To do this we removed 2 1inch oplev optics.  One was removed from the BS table, and wrapped in foil and put in a plastic box.  The other was just layed on its' side on the BS table. 

I then took the beam out of the BS chamber, in order to begin measuring the mode.  I left the flat fixed mirror in the place of what will be PZT SM1, and instead used the PZT mirror to turn the beam and get it out the BS chamber door.  (Thoughts of getting the beam to the BS oplev table were abandoned since this was way easier, since Kiwamu and Steve had made the nifty table leg things.)  Kiwamu and I borrowed an 2inch 45P Y1 optic from the collection on Koji's desk (since we have ZERO 2inch optics on the random-optic-shelf....no good), to shoot the beam down the hallway of the Yarm (new convention).  We used the beam scan on a rolling cart to measure the beam at various distances.  I made some sweet impromptu plum bobs to help make our distance measurements a bit more accurate.

We stopped at ~25 feet from the BS chamber, since the spot was getting too big for the beam scanner.  If it turns out that I can't get a good fit with the points I have, I'll keep everything in-chamber the same, and do the farther distances using the good ol' razor blade technique.

I have measurements for the distances between the beam scan head and the opening of the BS chamber.  Tomorrow, or very soon after, I need to measure the distances in-chamber between the MC and the BS chamber opening.  Plots etc will come after I have those distances.

Next on the to-do list:

1.  Measure distances in-chamber for first mode scan.

2.  Plot spot size vs. distance, see if we need more points. Take more points if needed.

3.  Put in MMT1, repeat measurements.

4.  Put in MMT2, rinse and repeat.

5.  Move the PZT mirror to its new place as SM1, and figure out how to connect it.  Right now the little wires are hooked up on the BS table, but we're going to need to make / find a connector to the outside world from the IOO table. This is potentially a pretty big pain, if we don't by happenstance have open connectors on the IOO table.

  2987   Wed May 26 00:50:16 2010 JenneUpdateIOOMirrors moved in prep for round 2 of MC mode measuring

[Jenne, Kevin, Kiwamu]

We moved some optics in preparation for measuring the MC mode after the first MMT curved optic, RoC -5m. 

Kevin and I found the box of DLC (sp?) mounts with the 2" Y1-45P optics in the clean tupperware boxes.  We removed one of the Y1-45P's, and replaced it with the MMT1 -5m optic, which was baked several weeks ago.  We left the Y1-45P on the cleanroom table next to where the MMT optics are.  We placed this MMT mirror in the place it belongs, according to Koji's table layout of the BS table. 

We drag wiped one of the other Y1-45P's that was in the box since it was dirty, and then placed the optic on the IOO table, on the edge closest to the BS table, with the HR side facing the BS table, so that the beam reflected off the curved mirror is reflected back in the direction of the BS table.  This was aligned so the beam hits the same PZT mirror we were using last time, to get the beam out of the BS chamber door.  We left a razor dump on the edge of the BS table, by the door, which will need to be removed before actual measurements can take place. 

Rana pointed out that the anticipated mode calculation should be modified to include the index of refraction of the crystals in the Faraday, and the polarizers in the Faraday.  This may affect where we should put MMT1, and so this should be completed before round 2 measurements are taken, so that we can move MMT1.

Also, the optics are in place now, and the beam is going out the BS chamber door, but we have not yet measured distances (design distances quoted on the MMT wiki page), and confirmed that everything is in the right place.  So there is a bit more work required before beginning to measure round 2.


Note:  While I was poking around on the BS table, I had to move several optics so that we could fit MMT1 in the correct place.  When preparing to move these optics, I found 2 or 3 that were totally unclamped. This seems really bad, especially for tall skinny things which can fall over if we have an earthquake.  Even if something is in place temporarily, please clamp it down.

  2993   Wed May 26 15:34:00 2010 JenneUpdateIOOMirrors moved in prep for round 2 of MC mode measuring


That's true. But I thought that you measured the mode after those optics and the effect of them is already included.


  • We need to model the transmissive optics in order to understand the measured mode which is different from the MC mode slightly.
  • We just can calculate the modes based on the measurement in order to figure out the realistic positions of the MMT1 and MMT2.


Rana pointed out that the anticipated mode calculation should be modified to include the index of refraction of the crystals in the Faraday, and the polarizers in the Faraday.  This may affect where we should put MMT1, and so this should be completed before round 2 measurements are taken, so that we can move MMT1.


 Yes, the measured mode takes all of this into account.  But in Kevin's plot, where he compares 'measured' to 'expected', the expected doesn't take the Faraday optics into account.  So I should recalculate things to check how far off our measurement was from what we should expect, if I take the Faraday into account.  But for moving forward with things, I can just use the mode that we measured, to adjust (if necessary) the positions of MMT1 and MMT2.  All of the other transmissive optics (that I'm aware of) have already been included, such as the PRM and the BS.  This included already the air-glass curved interface on the PRM, etc.

  3006   Fri May 28 11:26:35 2010 JenneUpdatePEMNew Foam Box installed


Valera and I put the 2 Guralps and the Ranger onto the big granite slab and then put the new big yellow foam box on top of it.

There is a problem with the setup. I believe that the lead balls under the slab are not sitting right. We need to cut out the tile so the thing sits directly on some steel inserts.

You can see from the dataviewer trend that the horizontal directions got a lot noisier as soon as we put the things on the slab.

 You'll have to ask Steve how deep he cut, but the tile is cut around the lead balls, so they are not sitting on the linoleum.  They might just be sitting on the concrete slab, or whatever Steve found underneath the tile, instead of fancy steel inserts, but at least they're not on the tile.  I don't know why things got noisier though...

  3010   Fri May 28 13:51:51 2010 JenneUpdateVACvacuum work


We started a vacuum work in this morning. And still it's going on.


Although the last night the green team replaced a steering mirror by an 80% reflector on the PLS table, the beam axis to the MC looks fine.

The MC refl beam successfully goes into the MCrefl PD, and we can see the MC flashing as usual.

We started measuring the distance of the optics inside the vacuum chamber, found the distance from MC3 to MMT1(curved mirror) is ~13cm shorter than the design.

We moved the positions of the flat mirror after the Faraday and the MMT1, but could not track the beam very well because we did not completely lock the MC.

Now we are trying to get the lock of the MC by steering the MC mirrors.



 Hey guys,

I just finished redoing the calc based on the measurements that happened last week.  Using the average of the Vert and Horz measurements in Kevin's elog 2986, I find that we need to make the MMT telescope ~8cm longer.  So, can you please place the flat mirror after the Faraday in the same place as the drawing, but move the MMT1 79mm farther away from that flat mirror?  Looking at the table layouts that Koji has on the wiki, this should still (barely) fit.

New distances:

d2a = 884.0mm (no change) ------  MC3 to Flat after Faraday

d2b = 1123.2mm (move MMT1 farther toward center of BS table)  -------- Flat after Faraday (SM1) to MMT1

d3 = 1955.0mm (result of moving MMT1)  ---------  MMT1 to MMT2

d4a = 1007.9mm (no chnage)        ----------- MMT2 to SM2

d4b = 495.6mm (no change) ------------ SM2 to PRM

  3011   Fri May 28 14:24:30 2010 JenneUpdateVACvacuum work

I just got off the phone with Alberto and Kiwamu, and I'm going to try to recalculate things based on their measurements of the distances between MC3 and SM1.  It sounds like the CAD drawings we have aren't totally correct.    I know that when we opened doors just before Christmas we measured the distances between the BS table and the ITM tables, but I don't think we measured the distance between the IOO table and the BS table.  Hopefully we can fit everything in our chambers.....

  3045   Thu Jun 3 14:13:20 2010 JenneUpdateIOOmode measurement of new input optics


I checked the measured data of the mode profile which was taken on the last Tuesday.

For the vertical profile,

the plot shows a good agreement between the expected radius which is computed from the past measurement, and that measured on the last Tuesday.

However for the horizontal profile,

it looks like being overestimated. This disagreement may come from the interference imposed on the Gaussian spot as we've been worried. 

So we should solve this issue before restarting this mode matching work.

 - The next step we should do are;

checking the effect of MMT1 on the shape of the beam spot by using spare MMT1



The expected curve in the attached figure were computed by using the fitted parameter listed on the entry 2984 .

In the calculation the MMT1 is placed at 1911mm away from MC3 as we measured.

And the focal length of MMT1 is set to be f=-2500mm.

 When / if you use the other MMT1 mirror, make sure to take note whether or not it says "SPARE" on it in pencil.  I don't remember if it's the other MMT1, or if it's one of the MMT2's that says this.  The mirror was baked, so it's okay to use in the vacuum, however it's the one which was dropped on the floor (just prior to baking), so any discrepancies measured using that optic may not be useful.  I don't know how strong the CVI coatings are to scratches resulting in being dropped from a ~1m height.  Bob and I didn't see any obvious big scratches that day, but that doesn't necessarily give it a clean bill of health. 

The optic labeled "SPARE" should NOT be used as the final one in the IFO.

  3076   Mon Jun 14 22:16:08 2010 JenneUpdateIOOMode scan after Mode Matching Telescope

[Jenne, Kiwamu]

We measured the mode after the Mode Matching Telescope. 


---- fitted parameters ----

       w0_h =  2.85 +/- 0.0115 mm

       w0_v =  2.835 +/- 0.00600 mm

       z0_h = 5.4 +/- 0.447  m

       z0_v  = 6.9 +/- 0.305  m

Attachment 1: after_MMT.png
  3094   Mon Jun 21 18:01:34 2010 JenneUpdate40m UpgradingSRM, PRM hung, magnets inspected

[Jenne, Kiwamu, Rana, Eric Gustafson]

The SRM and PRM have been re-hung, and are ready for installation into the chambers.  Once we put the OSEMs in, we may have to check the rotation about the Z-axis.  That was not confirmed today (which we could do with the microscope on micrometer, or by checking the centering of the magnets in the OSEMs).

Also, Eric and Rana inspected the Tip Tilt magnets, and took a few that they did their best to destroy, and they weren't able to chip the magnets.  There was concern that several of the magnets showed up with the coatings chipped all over the place.  However, since Rana and Eric did their worst, and didn't put any new chips in, we'll just use the ones that don't have chips in them.  Rana confiscated all the ones with obvious bad chips, so we'll check the strengths of the other magnets using a gaussmeter, and choose sets of 4 that are well matched. 

Eric, photographer extraordinaire, will send along the pictures he took, and we'll post them to Picasa.

  3098   Tue Jun 22 18:56:32 2010 JenneUpdateEnvironmentBad placement of recycling bin

Someone has been moving the big blue recycling bin in front of the laser-chiller-chiller (the air conditioner in the control room).  This is unacceptable.  The chiller temp was up to 20.76C.  No good. 

You are free to move the recycling bin around so you can access drawers or the bike-exit-door in the control room, but make sure that it does not block air flow between the chiller-chiller and the chiller. 

The attached photo shows the BAD configuration.

Attachment 1: BlockingLaserChillerChiller_small.jpg
  3099   Tue Jun 22 20:07:08 2010 JenneUpdate40m UpgradingFirst attempt at Tip Tilt hanging

[Jenne, Steve, Nancy, Gopal]

We made an attempt at hanging some of the Tip Tilt eddy current dampers today. 

Photo 1 shows the 2 ECDs suspended.


(1) Loosen the #4-40 screws on the side of the ECDs, so the wire can be threaded through the clamps.

(2) Place the ECDs in the locator jigs (not shown), and the locator jigs in the backplane (removed from main TT structure), all laying flat on the table.

(3) Get a length of Tungsten wire (0.007 inch OD = 180um OD), wipe it with acetone, and cut it into 4 ~8cm long segments (long enough to go from the top of the backplane to the bottom).

(4) Thread a length of wire through the clamps on the ECDs, one length going through both ECDs' clamps.

(5) One person hold the wire taught, and straight, and as horizontal as possible, the other person tightened the clamping screws on the ECDs.

(6) Again holding the wire in place, one person put the clamps onto the backplane (the horizontal 'sticks' with 3 screws in them).

(7) The end. In the future, we'll also clip off extra pieces of wire.

When we held up the backplane to check out our handy work, it was clear that the bottom ECD was a much softer pendulum than the top one, since the top one has the wire held above and below, while the bottom one only has the wire held on the top.  I assume we'll trim the wire so that the upper ECD is only held on the top as well?

Lessons learned:

* This may be a 3 person job, or a 2 people who are good at multitasking job.  The wire needs to be held, the ECDs need to be held in place so they don't move during the screwing/clamping process, and the screws need to be tightened.

* Make sure to actually hold the wire taught. This didn't end up happening successfully for the leftmost wire in the photo, and the wire is a bit loose between the 2 ECDs.  This will need to be redone.

* We aren't sure that we have the correct screws for the clamps holding the wire to the backplane.  We only have 3/16" screws, and we aren't getting very many threads into the aluminum of the backplane.  Rana is ordering some 316 Stainless Steel (low magnetism) 1/4" #4-40 screws.  We're going for Stainless because Brass (the screws in the photo), while they passed their RGA scan, aren't really good for the vacuum.  And titanium is very expensive.  

The 2nd photo is of the magnet sticking out of the optic holder.  The hole that the magnet is sitting in has an aluminum piece ~2/3 of the way through.  A steel disk has been placed on one side, and the magnet on the other.  By doing this, we don't need to do any press-fitting (which was a concern whether or not the magnets could withstand that procedure), and we don't need to do any epoxying.  We'll have to wait until the ECDs are hung, and the optic holder suspended, to see whether or not the magnet is sticking out far enough to get to the ECDs. 

Attachment 1: 2_ECDs_small.jpg
Attachment 2: MagnetStickingOutFar_small.jpg
  3104   Wed Jun 23 12:47:43 2010 JenneUpdateSUSPRM, SRM ready for vacuum

I fitzed with the PRM and SRM briefly, and I now believe that they're both ready to go into the chambers. 

For each optic, I used the microscope on a micrometer to check that the scribe lines on each side of the optic were at the same height.  Basic procedure was to center the microscope on one scribe line, move the microscope to the other side, to see how far the line was from center, and try to (very gently!!) rotate the optic in the wire about the z-axis about half the distance that the one scribe line needed to be.  Rinse and repeat several times until satisfied. 

I then checked that our HeNe oplev was still at 5.5" beam height, and that the beam traveled straight across the table.  I put the SRM in the oplev, unclamped the EQ stops, and waited for it to settle.  The HEPA filters were turned off, to minimize the breeze.  While the SRM settled, I worked on the height/rotation for the PRM on the other table. 

After checking the SRM balance, I clamped it and moved it, and checked the PRM balance, then turned off the HeNe and rewrapped everything in foil, and turned on the HEPAs.

Both the SRM and the PRM seem a little off in Pitch.  The beam returning to the QPD (placed just next to the laser) was always ~1cm above the center of the QPD.  The beam travel distance was ~3m (vaguely) from laser to optic to QPD.  This effect may be because the optics were originally balanced with OSEMs in place, and I didn't have any OSEMs today.  Koji and I found several months ago that the OSEMs have some DC affect on the optics.

Anyhow, since our optics are so small, I think the OSEMs and coils can handle this small DC offset in pitch, so I think we're ready to rock-n-roll with putting them in the chambers.

Still on the to-do list......Tip Tilts!

The photo shows the oplev beam position on (kind of) the QPD, for the SRM.  The PRM was basically the same.

Attachment 1: SRM_pitch_offset_small.jpg
  3115   Thu Jun 24 13:02:59 2010 JenneUpdateComputersSome lunchtime reboots

[Jenne, Megan, Frank]

We rebooted c1iovme, c1susvme1, and c1susvme2 during lunch.  Frank is going to write a thrilling elog about why c1iovme needed some attention.

C1susvme 1&2 have had their overflow numbers on the DAQ_RFMnetwork screen red at 16384 for the past few days.  While we were booting computers anyway, we booted the suses.  Unfortunately, they're still red.  I'm too hungry right now to deal with it....more to follow.

  3121   Fri Jun 25 15:22:45 2010 JenneOmnistructureSAFETYNo entry to the 40m LVEA until further notice!


The 40m corner station crane is out of order, and it's stuck in a way that prohibits entry to the 40m LVEA / IFO room for safety.  The crane has been locked out / tagged out. 

Until further notice, absolutely no one may enter the 40m LVEA.  Work is permitted in the desk / control room areas.

Signs have been posted on all doors into the LVEA.  Please consider those doors locked out / tagged out.


  3131   Tue Jun 29 08:55:18 2010 JenneFrogsEnvironmentWe're being attacked!


We're going to have to reinstate the policy of No food / organic trash *anywhere* in the 40m.  Everyone has been pretty good, keeping the food trash to the one can right next to the sink, but that is no longer sufficient, since we've been invaded by an army of ants:


We are going back to the old policy of Take your trash out to the dumpsters outside.  I'm sure there are some old wives tales about how exercise after eating helps your digestion, or something like that, so no more laziness allowed!

  3133   Tue Jun 29 11:48:17 2010 JenneConfigurationSAFETYBack in LASER HAZARD mode.

[Steve, Kiwamu, Jenne]

The 40m is now back in Laser Hazard mode.  Safety glasses are required for entry into the LVEA / IFO room.

  3139   Tue Jun 29 20:47:19 2010 JenneUpdatePEMTerminator put on Guralp Box

A little D-sub terminator was put on the Gur1 input to the Guralp box, to check again the noise level of the box.

  3147   Wed Jun 30 14:38:04 2010 JenneUpdatePEMGuralp terminator is switched

I moved the Guralp box's input terminator from Gur1 to Gur2 a minute or so ago to check the other channels.

  3149   Wed Jun 30 17:30:54 2010 JenneUpdatePEMSeismometers moved for MC Wiener work

Now that the MC is back up and running, I put the Guralp seismometers at the ends of the mode cleaner.  Gur1 is near MC2, and Gur2 is near MC1 (yes, it seems backwards....that's how the cable lengths work).  Also, the set of 3 MC2 accelerometers are in place under MC2.  I can't find the black cube for the other set of accelerometers, so there aren't any around MC1/3. 

  3154   Thu Jul 1 14:28:39 2010 JenneUpdatePEMMC1 Accelerometers in place

Kevin sent me an email with top secret info on where one of the other accelerometer cubes was hiding (it was with his shaker setup on the south side of the SP table), so I took it and put the 3 MC1 accelerometers in their 3-axis configuration. 

Also, I changed the orientation of both sets of 3 axis accelerometers to reflect a Right Handed configuration, to go along with the new and improved IFO configuration.  Previously (including last night), the MC2 accelerometers were together in a Left Handed configuration.

  3162   Tue Jul 6 17:38:27 2010 JenneUpdateSUSTip Tilt Progress!

[Jenne, Kyung Ha]

We successfully suspended the 4 eddy current dampers for the first Tip Tilt.  We had some lessons learned, including how to carefully get an allen wrench in between the dampers to do up some of the screws, and how to be careful not to bend the wire while tightening the screws.  More tomorrow...

  3171   Wed Jul 7 19:41:27 2010 JenneUpdateSUS1.5 more ECD sets suspended for tip tilts

[Jenne, Kyung Ha]

We made some good progress on suspending the Tip Tilt ECDs today.  We finished one whole set, plus another half.  The half is because one of the screw holes on the lower right ECD somehow got cross threaded.  The ECD and screws in question were separately wrapped in foil to mark them as iffy.  We'll redo that second half tomorrow.  This makes a total of 2.5 (including yesterday's work) ECD backplanes suspended.  The only thing left for these ones is to trim up the excess wire.

We also (with Koji) took a look at the jig used for suspending the mirror holder.  It looks like it was designed for so many Tip Tilt generations ago as to be basically useless for the 40m TTs.  The only really useful thing we'll get out of it is the distance between the suspension block and the mirror holder clamps.  Other than that we'll have to make do by holding the mirror and block at the correct distance apart, utilizing a ruler, calipers, or similar.  Rana pointed out that we should slightly bend the blade springs up a bit, so that when they are holding the load of the mirror holder, they sit flat. 

Attached below are 2 different pictures of one of the ECD backplane sets that has been suspended.  One with black background to illustrate the general structure, and one with foil background to emphasize the wires.

Attachment 1: ECDbackplane_blackdump_small.jpg
Attachment 2: ECDbackplane_foil_small.jpg
  3172   Wed Jul 7 22:22:49 2010 JenneUpdateComputersSome channels not being recorded!!!

[Rana, Jenne]

We discovered to our great dismay that several important channels (namely C1:IOO-MC_L, but also everything on c1susvme2) are not being recorded, and haven't been since May 17th.  This corresponds to the same day that some other upgrade computers were installed.  Coincidence?

We've rebooted pretty much every FE computer and the FrameBuilder and DAQ_CONTROL approximately 18 times each (plus or minus some number).  No matter what we do, or what channels we comment out of the C1SUS2.ini file, we get a Status on the DAQ_Detail screen for c1susvme2 of 0x1000.  Except sometimes it is 0x2000.  Anyhow, it's bad, and we can't make it good again. 

I have emailed Joe about fixing this (with some assistance from Alberto, since we all know how much he likes doing the Nuclear Reboot option for the computers :)

  3196   Mon Jul 12 14:22:36 2010 JenneSummaryPSLThings I did to the PSL today: Refcav, PMC, cameras, etc.


I re-aligned the beam into the PMC. I got basically no improvement. So I instead changed the .LOW setting so that PMCTRANS would no longer go yellow and make the donkey sound.

I did the same for the MOPA's AMPMON because its decayed state is now nominal.

[Jenne, Chip]

The alarm was still going, because the LOLO setting was higher than the LOW, which is a little bit silly.  So we changed the .LOLO setting to 0.80 (the LOW was set to 0.82)

We also changed psl.db to reflect these values, so that they'll be in there the next time c1psl gets rebooted.

  3205   Tue Jul 13 11:51:19 2010 JenneUpdatePEMGur1 has no signal?!?!?!?!

[Sanjit, Jenne]

Sanjit discovered that the Gur1 channels are all digital 0.  We determined that this began on July8, 04:00 UTC (~9pm on the 7th?).

It's digital zero, so we suspect a software thing.  Just to check, we put a sine wave in, and didn't see anything.  Gur2 seems totally fine, and the sine wave input showed up nicely on dataviewer.  What's going on? Sabotage to prevent this paper from getting done?  Dmass trying to get his paper done before me???

Investigations are ongoing.... Joe claims it's not his fault, since his shenanigans near the PEM rack were on days before, and days after this, but not on the 7th.  

Attachment 1: Gur1_noSignal_13Jul2010.png
  3211   Tue Jul 13 23:20:37 2010 JenneUpdatePEMGur1 has no signal?!?!?!?!


[Sanjit, Jenne]

Sanjit discovered that the Gur1 channels are all digital 0.  We determined that this began on July8, 04:00 UTC (~9pm on the 7th?).

It's digital zero, so we suspect a software thing.  Just to check, we put a sine wave in, and didn't see anything.  Gur2 seems totally fine, and the sine wave input showed up nicely on dataviewer.  What's going on? Sabotage to prevent this paper from getting done?  Dmass trying to get his paper done before me???

Investigations are ongoing.... Joe claims it's not his fault, since his shenanigans near the PEM rack were on days before, and days after this, but not on the 7th.  

 I just rebooted c0dcu1, which didn't help anything.  Joe said he'd try to give me a hand tomorrow.

  3220   Wed Jul 14 16:39:06 2010 JenneUpdateDAQDebugging Guralp and reboots

[Joe, Jenne]

Joe got on the phone with Alex, and Alex's magic Alex intuition told him to ask about the RFM switch.  The C0DAQ_CTRL's overload light was orangeAlex suggested hitting the reset button on that RFM switch, which we did. That fixed everything -> c0dcu1 came back, as did the frame builder.  Rana had pointed out earlier that we could have brought back all of the other front ends, and enabled the damping of the optics even though the FB was still down.  It's okay to leave the front ends & watchdogs on, and just reboot the FB, AWG, and DAQ_CTRL computers if that is necessary.

Anyhow, once the FB was back online, we got around to bringing back all of the front ends (as usual, except for the ones which are unplugged because they're in the middle of being upgraded).  Everything is back online now.

After all of this craziness, all of the Guralp channels are working happily again. It is still unknown why they starting being digital zero, but they're back again. Maybe I should have rebooted the frame builder in addition to c0dcu1 last night?



This is regards to zero signal being reported by the channels C1:PEM-SEIS_GUR1_X, C1:PEM-SEIS_GUR1_Y, and C1:PEM-SEIS_GUR1_Z.

I briefly swapped Guralp 1 EW and Guralp 2 EW to confirm to myself that it was not on the gurlap end (although the fact that its digital zero is highly indicative a digital realm problem).  I then unplugged the 17-32, and then 1-16 channel connections to the 110B.  I saw floating noise on the GUR2 channels, but still digital zero on the GUR1 channels, which means its not the BNC break out box.

There was a spare 110B, unconnected in the crate, so to do a quick test of the 110B, I turned off the crate and swapped the 110Bs, after copying the switch configuration of the first 110B to the second one.  The original 110B was labeled ADC 1, while the second 110B was labeled ADC 0.  The switches were identical except for the ones closest to the Dsub connectors on the front.  All those switches in that set were to the right, when looking down at the switches and the Dsub connectors pointing towards yourself.

Unfortunately, the c0duc1 never seemed to come up with the new 110B (ADC 0).  So we put the original 110B back.  And turned the crate back on. 

The fb then didn't seem to come back quite right.  We tried rebooting fb40m it, but its still red with status 1.  c0daqctrl is green, but c0dcu1 is red, although I'm not positive if thats due to fb40m being in a strange state.  Jenne tried a telnet in to port 8087 and shutdown, but that didn't seem to help.  At this point, we're going to contact Alex when he gets in around 12:30.



  3249   Tue Jul 20 11:49:31 2010 JenneUpdateSUSSome Suspensions not damping

[Jenne, Koji]

I moseyed into the control room this morning, to find ITMX and ITMY both with their watchdogs tripped.  ITMY (new convention) wouldn't damp.  Koji discovered that there was a sign flip in 2 of the sensors.  A set of reboots of c1susvme1&2 fixed the problem. 

A side note:  For the ETMs, the OSEM sensor readouts are gigantic (~20,000), whereas for the similar channels on all other optics, the readouts are on the order of 1.  After some looking around, it seems that this is just the way things have been (for at least 100 days), and the filters in the SUSPOS and other SUS filter banks have a high pass filter to take care of this.  It's weird, but it seems to be the way it is, and the ETMs damp, so it's all good.

  3295   Mon Jul 26 20:30:35 2010 JenneUpdateSUS2 Tip Tilts suspended and balanced

[Koji, Jenne]

We were on Team Cleanroom, while Kiwamu and Alberto were on Team Chamber.  Team Cleanroom suspended and balanced 2 Tip Tilts this afternoon.

One of the TTs that was suspended today is the one which was broken on Friday (see elog 3278).  We resuspended it using the regular 0.0036" diameter wire (91um).  We balanced it using the HeNe oplev, and then set it aside.  This TT has serial number 2.

We noticed that, like the previous 2 TT suspensions (this one before it was broken, and the one actually installed in the BS chamber on Friday, which is #3), there seems to be a little bit of hysteresis in the pointing.  The difference comes if we poke the top of the mirror holder and observe the place the reflected beam spot comes to rest at, and if we poke the bottom of the mirror holder.  The beam spot stays a little higher when we poke the top vs. when we poke the bottom. 

To combat this, we tried suspending our second TT of the day (the one that Kyung Ha and I had half finished) using thinner wire for the mirror holder.  We used the 0.0017" diameter wire (43um) that is used for the SOSes.  Unfortunately, it still seems like there is a similar hysteresis.  The thin-wire TT has serial number 4.

While working on TT4, we recalled that we have to include rubber dampers for the vertical blade springs.  Oooops!  We used some of the leftover #4-40 screws with viton tips that Zach and Mott had made for Earthquake stops to damp the vertical resonance of the blades.  We measured the Q factor by flicking the blades up or down.  We changed the oplev setup to be a shadow sensor setup, and watched the ringdown of the vertical mode on the 'scope.  We counted #cycles/time = frequency, and the t(1/2) time for the exponential ringdown to calculate the Q.  For the shadow sensor, we positioned the QPD in line with the initial HeNe beam, and placed the edge of the mirror holder clamp partially in the beam, so the beam was partly occluded.  When the mirror shook up and down, more or less of the beam was blocked, and we could see this power fluctuation on the 'scope.

Using the formula Q = pi  f0 T1/2 / ln(2) = 4.53 f0 T1/2, where T1/2 is the the time it takes for the amplitude to decay by half, we measured a Q of 31 for the vertical mode with no damping, and a Q of 14 with damping.  Koji confirmed the calculation and put it into wiki.

We need to go through the other TTs that have been assembled and give them their rubber dampers.


  3303   Tue Jul 27 23:46:45 2010 JenneUpdateSUSQ measurements of 2 TTs

[Koji, Jenne]

We took measurements of the Q of all the modes that we could think of for TT#4, and then repeated several of the same measurements for TT#2.  We noticed that when we took off the backplane and then replaced it on TT#4, the pitch pointing had changed, so we had to repeat the balancing procedure by slightly shifting the position of the wire clamps relative to the mirror holder. No fun. We decided to quit removing the backplanes. 

The main conclusion of this evening's measurements of TT#4 is that everything looks very close to the design ideas.  Good work team!


'Free Swinging' values (just for interest)

Vert, no damping:   Q = 31.4

Pitch, no damping (ECD backplane removed): Q = ~700

Yaw, no ECDs: Q = ~900

Pos, no ECDs (no measurement) - we had already put the backplane back on, and didn't want to take it off again.


Damped Values:

Vert, with damping: Q = 14.3

Pitch, with ECDs: overdamped, so Q < 1/2

Yaw, with ECDs: Q = 2.3

Pos, with ECDs: Q = 1.4

Side, with ECDs: Q = 1.9


We also measured the resonant frequency of each of the ECDs for this TT (since we had the backplane removed anyway...)

ECD UL: 10.05Hz

ECD UR: 10.15Hz

ECD LL: 10.21Hz

ECD LR: 10.21Hz



Yaw, with ECDs: Q = 7.0

Pitch, with ECDs: overdamped, so Q < 1/2

Vert: Problematic.  No damping, f = 25.9Hz, Q = 36.  With rubber dampers, f = 20.0Hz, Q = 42.   Yes, you read that right.  The frequency is lower, and the Q is higher *with* the damping.  Perhaps our brains are fried.  Perhaps we've discovered new, inconsistent physics (awfully unlikely....). We'll revisit this again tomorrow to figure out what mistake we're making.

  3314   Wed Jul 28 18:24:57 2010 JenneUpdateGreen Locking2 Green Periscopes have mirrors, aligned

[Koji, Jenne, Kiwamu]

This is to describe the work that went on in the Cleanroom today.  Kiwamu's entry will detail the tidbits that happened in the chamber.

We engraved the periscope mounts with the mirror info for the mirrors which were placed in the periscope.  We also engraved the barrels of the optics with their info, for posterity.  Koji carefully put the mirrors into the periscopes.  Since we have wedged optics, the goal was to have the front HR surface of the mirror parallel to the plane of the mount, and leave a bit of space behind one side of the optic (if we just pushed the optic fully in, the HR surface wouldn't be flat, and would send the beam off to the left or right somewhere).  Once the mirrors were mounted in the periscopes, we checked the vertical levelness of the outcoming beam.  For the first periscope (the one which has been installed on the BS table), the beam was deflected upward (2.5)/32 inches over 55inches.  This corresponds to a 1.4mRad vertical deflection.  The second periscope (which will eventually be installed on the OMC table) had a deflection of 1/32 over 55inches, or 0.6mRad.  We did not check the side-to-side deflection for either of the periscopes.

We also engraved one more DLC mount with mirror info, and put a mirror into the mount.  This is one of the optics that was placed onto the BS table today, which Kiwamu will describe.

We removed TT#3 from the BS chamber so that it could have rubber vertical dampers installed, and be characterized.  For future reference, the #'s of the Tip Tilts refers to the serial number of the suspension block piece, which forms the top horizontal bar of the frame. 

  3334   Fri Jul 30 17:24:22 2010 JenneUpdatePEMGuralps back in the 40m

I brought the GUR2 seismometer back from Bridge so I can get some more MC/Seismic data during the next week while we're pumped down, before we start doing things to the PSL table.  Both of the Gur Seismometers are connected back up to the breakout box as of ~3:27pm today.  Alastair still has the handheld controller thing (which I use for mass centering, on occasion), since he'll want the seismometer back in a week or two when I'm done with it.


Something is wrong with both X channels of the Guralps.  Alastair claimed that he and Frank didn't do anything bad when they opened up the breakout box, but I am suspicious. 


While I'm at it, a reminder that Jan and his SURF student Greg still have the Ranger, disassembled over in Bridge.  They made a note in their elog, but not in the 40m elog when they took it back again.

Whenever you're done with the Mode Cleaner for the next week, please make sure it is locked, nicely aligned and happy before you leave.  Also please make a note of what you're doing and when, so that I know what is good data and what is data with unusual conditions.

In other, semi-bad news (but already recovered from), when I was finishing putting the Guralp Breakout Box back in the rack, I bumped the power strip that is on the top back side of the rack, near the corner that the door opens on (not the corner the door hinges on).  I turned the power strip back on, and I think everything that is connected to it came back okay.  Anyhow, my bad. Sorry. 

  3349   Mon Aug 2 18:02:46 2010 JenneUpdatePEMSeismometer Update: Still not good, but perhpas getting better

Today's seismometer diagnosis activities are still underway, this is just an update (since I did some reboots):

Problem 1: X and Z channels on both seismometers were flipped.  I unplugged an X cable (East/West on the cable labels) and the Z channel (vert) would go to floating ADC zero.  Rana suggested that the ADCs sometimes have random channel hopping, and that a reboot of the c0dcu1 computer which handles the PEM ADCU should fix this problem.  I keyed the c0dcu1 / c0daqawg crate, those computers came back just fine, and the channels were no longer flipped.  This is a good thing.  Although now it's actually the Z channels that were / are bad on both seismometers, not the X's.

While rebooting those computers, c1iovme, c1sosvme, c1susvme1 and c1susvme2 crashed.  I rebooted them, although for the first few power cycles c1susvme1&2 couldn't mount /cvs/cds/caltech.  Eventually they did, and life is good again.  Except that the seismometers are still funny.

  3351   Tue Aug 3 01:51:01 2010 JenneUpdatePEMSeismometer Update: Still not good, but perhaps getting better


Today's seismometer diagnosis activities are still underway, this is just an update (since I did some reboots):

Problem 1: X and Z channels on both seismometers were flipped.  I unplugged an X cable (East/West on the cable labels) and the Z channel (vert) would go to floating ADC zero.  Rana suggested that the ADCs sometimes have random channel hopping, and that a reboot of the c0dcu1 computer which handles the PEM ADCU should fix this problem.  I keyed the c0dcu1 / c0daqawg crate, those computers came back just fine, and the channels were no longer flipped.  This is a good thing.  Although now it's actually the Z channels that were / are bad on both seismometers, not the X's.

While rebooting those computers, c1iovme, c1sosvme, c1susvme1 and c1susvme2 crashed.  I rebooted them, although for the first few power cycles c1susvme1&2 couldn't mount /cvs/cds/caltech.  Eventually they did, and life is good again.  Except that the seismometers are still funny.

 Some more progress, but still not complete:

Jan and I looked at all of the Gur channels on a 'scope (battery, so as not to be grounded), and 5 of the 6 looked good.  We were looking at the BNCs just as they go into the ADC.  The one which still looks bad is Gur1Z.  The 'scope just doesn't see any signal on that channel. 

In addition, the ADC's BNC input #4 (which normally has Gur2Z) looks totally shot.  When it's floating, the signal on dataviewer definitely doesn't look floating.  I'm probably going to have to move over to another channel, and just give that one up (this ADC already has several channels which have been declared bad, so maybe it's not a surprise that this can happen?)

Since one of the Gur signals looks bad (Gur1Z) and one of the ADC channels looks bad (usual Gur2Z), I switched the Z channels on the ADC board, so the channel being saved as Gur1Z is in fact Gur2Z.  This is valid as of ~1:15am until further elog notice.

During my investigations into why Gur1Z is funny, I also looked at the signal on the BNC octopus cable coming straight from the output of the Guralp Breakout Box (this is the cable which goes from "ADC Out" on the back of the box which is a 37 pin D-sub to 9 differential BNCs), and sometimes I saw zero on the 'scope, but sometimes there was a signal which would coincide with jumping tests.  Whenever there was a signal however, it was always a way lower amplitude (at least by a factor of 10?) than the other channels.

All of this craziness led to me pulling the Guralp box to investigate. 

Upon opening the box, I recalled that the channels go in order: Vert, NS, EW.  The Gur1Z channel is that first vert channel, and it's the one which always had a blue input capacitor rather than a surface mount one.  Being suspicious of Frank and Alastair, since they seemed unhappy with my capacitor choices, I wondered if they had wiggled the blue cap, and tore something loose.  Just in case, and to make things seem more uniform, I replaced the blue cap with a surface mount 1uF cap.  (Actually its 0.909uF, replacing the 0.905uF blue cap, according to the black DMM that measures capacitance.) While I was in there, since it had been a problem in the past (elog 2811), I relflowed the solder on some of the resistors, especially near the output op amp. 

Anyhow, none of that may have been necessary.  All 6 of the Gur channels were examined on a 'scope, using clip doodles to measure the various Test Points on the circuit.  I looked at all of the TPs in Gur1Z, and I didn't find that any particular stage was any noisier than the others.  Also, all 6 of the Gur channels seemed totally fine in terms of sending a good signal to the output of the box, including Gur1Z which is currently under investigation.  All of the channels passed the "output looks ~20x the input" test, and for approximately equal thumping on the ground all 6 channels seemed to have similar amplitude outputs.  The Z channels on both channels one and channels two were a little bigger than the X's or Y's, but the 2 Z channels were about the same.  This test was done using Guralp2 and the Gur2 cable on both channels 1 and 2, and then checked with Guralp 1, using the Gur2 cable on channels 1.  The Vert1 channel always seemed good.

I now am suspicious of one or more of the cables: either the Gur1 cable from the seismometer to the box, or the Vert1 channel of the octopus cable.  I'm satisfied that the BNC cables running through the cable tray are okay (although it might not hurt to check that they all successfully send a sine wave...)  I opened up the backshell of the Gur1 cable, on the end that connects to the breakout box.  Nothing seemed amiss.  I still need to Beep the cable to check its connections, and look at the octopus cable. 

Recap / Current Status:  Breakout Box is reinstalled, both seismometers hooked up.  The Z channels on the seismometers are swapped at the ADC input. The dataviewer channels Gur1_X, Gur1_Y, Gur1_Z (which is actually Z of Gur2 seismometer) and Gur2_X, Gur2_Y are all good.  Nancy is going to leave the MC in a happy place, and note the time when she's done. Tomorrow I'll check out the cables for the Gur1Z seismometer channel. 

  3354   Tue Aug 3 11:50:16 2010 JenneUpdatePEMSeismometer Problem Tracked down

After some cable swapping this morning, I have determined which cable is bad.  It's the Gur1 cable between the seismometer and the breakout box.  This is a milspec -> 37pin d-sub cable.  I'll pull out the cable and have a look at it after lunch.

  3356   Wed Aug 4 03:01:56 2010 JenneUpdatePEMCatastrophic Cable Failures


After some cable swapping this morning, I have determined which cable is bad.  It's the Gur1 cable between the seismometer and the breakout box.  This is a milspec -> 37pin d-sub cable.  I'll pull out the cable and have a look at it after lunch.

 So, I was wrong about which cable it was, probably in my rush to get some lunch.  The actual culprit was the octopus cable that Bob made waaay back in the day (~2 years ago) to go from the "ADC out" of the breakout box (37pin Male Dsub) to 9 BNCs.  As it turns out, the Gur1Z channel of that cable was broken on both ends!!! 

On one end, we have the 37 pin Dsub.  The cable used was so thick (way too thick for this application) that it made a super rigid connection between the wires and the connector, and any bending of the cable stressed this connection, despite the strain-relief of the backshell.  The Gur1Z connection snapped off when I was gently wiggling the connections to check them out.  Also, since the wires were all so thick, they didn't really fit into the hole in the backshell, so 2 or 3 of them were squished.....straight through the insulation so that several channels were shorted together / potentially shorted to ground.  This may explain some of the nasty behavior that Rana and I had seen (although I might have forgotten to elog? My bad.) that even with the inputs of the breakout box all terminated, there was high coherence between the channels.  Terminated inputs should give random noise, so this was fishy. 

On the other end of the cable we have the 9 BNCs.  I had finished redoing the 37pin end of the cable, and was 'beeping' it to check it out, when to my dismay I found that the Gur1Z channels (the inside and the outer shield of the BNC connector) were shorted together.  I removed these 2 wires from the Dsub connector to confirm that the BNC was at fault.  Koji looked at the BNC with me after I chopped it off of the cable.  Bad news strikes again.  To get the wires to fit in the inner pin of the BNC connector, the cable-maker had cut off several strands of the wire to make it skinnier.  It appears that over the years these cut-off strands wiggled their way to touching the outer shield.  This appears to be a danger for all of the BNCs on this cable: a little bit of torque (which one might expect during plugging and unplugging a BNC) and the 2 sides of the differential measurement will be shorted together.

I then decided to start afresh and make my own cable.  I found some AWG26 8-twisted-pair cable laying around underneath the Yarm (since this was all I could find, I was just going to do the Gur1 and Gur2 channels, and leave out the Gur3's).  The 37 Dsub side was easy, but I seem not able to connect such skinny wire to the BNC connectors in a robust way.  Since this bad cable has so far cost me ~2.5 16-hour days of grief, I don't want my new version of it to also be bad.  At this point, I await the advice of one wiser than I. I think BNC connectors are designed for something a little closer to ~20AWG, but I could be wrong.  Also, they are obviously optimized for coax cable. So what I have now is never going to be great.  Maybe tomorrow I can go to the Electronics Shop / Store and buy BNC connectors that are meant to be soldered-to.  That would be awesome.

Since I currently have no functional cable to go from Breakout box to ADC, the Guralps are unplugged for tonight.

Conclusions for the day / evening:  Frank, Alastair and Jenna are mostly absolved of blame, although the traveling to Bridge and opening and closing the box (which usually involves more plugging and unplugging of cables) probably didn't help this cable out too much.  Also, Bob definitely owes me a Sugar Napoleon or something.

 In other news, since the Gur2Z ADC channel is totally wacked, I have taken over (but not renamed) the Ranger channel for Gur2Z for now.  Jan still has the Ranger hostage over in Bridge, so this is okay for now.

  3362   Wed Aug 4 20:15:07 2010 JenneUpdatePEMYay! Guralps work again!

After much hassle, the Guralp cable from the ADC Out of the breakout box to the ADC is fixed, and everything is plugged in and working again.  The seismometers are back in their regular positions at the ends of the MC, ready for some excellent seis/MC combo data. 

I solidified the change of putting the Gur2Z channel into a different BNC input on the ADC.  The C1ADCU_PEM.ini file has been changed so that what used to be the Ranger's channel is now recognized as Gur2Z. 

Also, I changed the same .ini file to reflect Koji's move of ACC_MC1_Z to the old AUDIO_MIC2 channel, so now all 6 Accelerometer channels have the same calibrations again.

Another big change is the change from old-left-handed convention to new-right-handed convention.  The seismometers are aligned the same way they always have been (with the North-South markers aligned with the MC), but now the North-South output is plugged into the BNC on the ADC that is associated with Gur*_X, and the East-West output is plugged into the ADC channel associated with Gur*_Y.  This is true for both Guralp Seismometers. 

So, now we have:

Gur1_X = Gur1_NS = ADC#10

Gur1_Y = Gur1_EW = ADC#11

Gur1_Z = Gur1_Vert = ADC#12

Gur2_X = Gur2_NS = ADC#2

Gur2_Y = Gur2_EW = ADC#3

Gur2_Z = Gur2_Vert = ADC#24

SEIS_Ranger_Y = no longer in the .ini file

  3373   Fri Aug 6 12:22:04 2010 JenneUpdateIOOMC data taking over the weekend

Nancy has the Mode Cleaner for her work for the night, and is going to leave the MC happy, locked, autolocker on, WFS enabled, the works, and write down in the elog the time that she's finished. After that, I'm taking MC/seismic data all weekend long.  During the weekend, if at all possible, please don't go into the IFO room, especially near the Mode Cleaner.  If you do need to go into the IFO room, please elog the time you went in, and the time you left so I can correlate it with my dataThis is actually important, so please stick a quick elog entry in if you even think about opening the doors to the IFO room. It is much appreciated. 

  3416   Thu Aug 12 23:41:48 2010 JenneUpdateelogrestarted



 More of the same. 

Who is putting weird figures into the elog?!?!  I haven't checked lately, but this is what usually crashes the elog.  It's been happening a lot lately, and it might be the .pdf's. 

Let's play a new game.  We'll call this game "Everyone only use .png files for the next week" Ready? GO!

ELOG V3.1.3-