I might have found the problem with the PLL that was preventing me from scanning the frequencies by 100KHz steps. A dumb flimsy soldering in the circuit was making the PLL unstable.

After I fixed that problem and also after writing a cleverer data acquisition script in Python,  I was able to scan continuosly the range 10-200MHz in about 20min (versus the almost 1.5-2 hrs that I could do previously). I'm attaching the results to this entry.

The 'smears' on the right side of the resonance at ~33MHz, are due to the PSL's sideband. I think I know how to fix that.

As you can see, the problem is that the model for the cavity transmission still does not match very well the data. As a result, the error on the cavity length is too big (~> 10 cm - I'd like to have 1mm).

Anyway, that was only my first attempt of scanning. I'm going to repeat the measurement today too and see if I can come out better. If not, than I have to rethink the model I've been using to fit.

I want to try to do the measurement with the network analyzer used as local oscillator, instead of the Marconis that I'm using now. Tha could give me better noise rejection. It would also give me information about the phase.

Also I wouldn't dislike abandoning the GPIB interfaces to acquire data.

I have made a prototype circuit of the triple resonant EOM.

The attached is the measured optical response of the system.

The measured gains at the resonances are 8.6, 0.6 and 7.7 for 11MHz, 29.5MHz and 55MHz respectively.

I successfully got nice peaks at 11MHz and 55MHz. In addition resultant optical response is well matched with the predicted curve from the measured impedance.

However there is a difference from calculated response (see past entry) (i.e. more gains were expected)

Especially for the resonance of 29.5MHz, it was calculated to have gain of 10, however it's now 0.6. Therefore there must a big loss electrically around 29.5MHz.

I am going to re-analyze the impedance and model the performance in order to see what is going on.

Hey, this looks nice, but can you provide us the comparison of rad/V with the resonant EOM of New Focus?

The commercial resonant EOM of New Focus has the modulation efficiency of 50-150mrad/Vrms. ( This number is only true for those EOM made from KTP such as model4063 and model4463 )

Our triple-resonant EOM (made from KTP as well) has a 90mrad/Vrms and 80mrad/Vrms at the reosonances of 11MHz and 55MHz respectively.

Therefore our EOM is as good as those of company-made so that we can establish a new EOM company

A few machines have still not been changed over, including a few laptops, mafalda, ottavia, and c0rga.

All the front ends have been changed over.

fb40m died during a reboot and was replaced with a spare Sun blade 1000 that Larry had.  We had to swap in our old hard drive and memory.

All the front ends, belladonna, aldabella, and the control room machines have been switched over. Nodus was changed over after we realized we hosed the elog and svn by switching linux1's IP.

At this point, 90% of the machines seem to be working, although c0daqawg seems to be having some issues with its startup.cmd code.

After Joe left:

1. Turned on op440m and returned him his keyboard and mouse.
2. Damped MC2.
3. Opened PSL shutter - locked PMC, FSS,
4. Started StripTool displays on op540m.
5. op340m doesn't respond to ping from anyone.
6. started FSS  SLOW and RCPID scripts on op540 - need to kill and restart on op430m.
7. ASS wouldn't come up - it doesn't know who linux1 is.
8. MC autolocker wouldn't run on op540m because of a perl module issue, started it on op440m - it needs to be killed and restarted on op430m.
9. probably mafalda, linux2, and op430m need some attention - they are all in the same rack.

As of 7:18 PM, the MC is locked and the PSL seems normal + all suspensions are damped and the ELOG is back up as well as the SVN.

5) op340m has had its hosts table and other network files updated.  I also removed its outdated hosts.deny file which was causing some issues with ssh.

6) On op340m I started FSSSlowServo, with "nohup ./FSSSlowServo", after killing it on op540m.

I also kill RCthermalPID.pl, and started with "nohup ./RCthermalPID.pl" on op540m.

7) c1ass is fixed now.  There was a typo in the resolv.conf file (namerserver -> nameserver) which has been fixed.  It is now using the DNS server running on linux1 for all its host name needs.

8) I killed the autlockMCmain40m process running on op440m, modified the script to run on op340m, logged into op340m, went to /cvs/cds/caltech/scripts/MC and ran nohup ./autolockMCmain40m

9) Linux2 does not look like it has not been connected for awhile and its wasn't connected when we started the IP change over yesterday.  Is it supposed to still be in use?  If so, I can hook it up fairly easily.  op340m, as noted earlier, has been switched over.  Mafalda has been switched over.

10) c0rga has now been switched over. 

11) aldabella, the vacuum laptop has had its starting environment variables tweaked (in the /home/controls/.cshrc file) so that it looks on the 192.168.113 network instead of the 131.215.113.  This should mean Steve will not have any more trouble starting up his vacuum control screen.

12) Ottavia has been switched over.

13) At this time, only the GPIB devices and a few laptops remain to get switched over.

Koji pointed out that logging into Nodus was being abnormally slow.  I tracked it down to the fact we had forgotten to update the address for the DNS server running on linux1 in the resolv.conf file on nodus.  Basically it was looking for a DNS server which didn't exit, and thus was timing out before going to the next one.  SSHing into nodus should be more responsive.

I have measured the linearity of our triple resonant EOM (i.e. modulation depth versus applied voltage)

The attached figure is the measured modulation depth as a function of the applied voltage.

The linear behavior is shown below 4Vrms, this is good.

Then it is  slowly saturated as the applied voltage goes up above 4Vrms.

However for the resonance of 29.5MHz, it is difficult to measure below 7Vrms because of the small modulation depth.

 - - - - result from fitting - - -

11MHz: 91mrad/Vrms+2.0mrad

29.5MHz: 4.6mrad/Vrms+6.2mrad

55MHz:82mrad/Vrms+1.0mrad

The GPIB interfaces have been updated to the new 192.168.113.xxx addresses, with Alberto's help.

Spare ethernet cables have been moved into a cabinet halfway down the x-arm.

The illuminators have a white V error on the alarm handler, but I'm not sure why.  I can turn them on and off using the video screen controls (except for the x arm, which has no computer control, just walk out and turn it on).

There's a laptop or two I haven't tracked down yet, but that should be it on IPs. 

At some point, a find and replace on 131.215.xxx.yyy addresses to 192.168.xxx.yyy should be done on the wiki.  I also need to generate an up to date ethernet IP spreadsheet and post it to the wiki.

Non-testpoint channels seem to be working in data viewer, however testpoints are not.  The tpman process is not running on fb40m.  My rudimentary attempts to start it have failed. 

# /usr/controls/tpman &
13929
# VMIC RFM 5565 (0) found, mapped at 0x2868c90
VMIC RFM 5579 (1) found, mapped at 0x2868c90
Could not open 5565 reflective memory in /dev/daqd-rfm1
16 kHz system
Spawn testpoint manager
no test point service registered
Test point manager startup failed; -1

It looks like it may be an issue with the reflected memory (although the cables are plugged in and I see the correct lights lit on the RFM card in back of fb40m.)

The fact that this is a RFM error is confirmed by /usr/install/rfm2g_solaris/vmipci/sw-rfm2g-abc-005/util/diag/rfm2g_util and entering 3 (which should be the device number).

Interestingly, the device number 4 works, and appears to be the correct RFM network (i.e. changing ETMY lscPos offset changes to the corresponding value in memory).

So, my theory is that when Alex put the cards back in, the device number (PCI slot location?) was changed, and now the tpman code doesn't know where to look for it.

Edit: Doesn't look like PCI slot location is it, given there's 4 slots and its in #3 currently (or 2 I suppose, depending on which way you count).  Neither seems much the number 4.  So I don't know how that device number gets set.

In the last two days Steve and I took some optics away from the both ETM end table.

This is because we need an enough space to set up the green locking stuff into the end table, and also need to know how much space is available.

Optics we took away are : Alberto's RF stuff, fiber stuff and some optics obviously not in used.

The picture taken after the removing is attached. Attachment1:ETMX, Attachment2:ETMY

And the pictures taken before the removing are on the wiki, so you can check how they are changed.

http://lhocds.ligo-wa.caltech.edu:8000/40m/Optical_Tables

Looks good. I just thought of the idea that we also can use Alberto's PLL setup to sense the modulation with more sensitivity.  ;-)

I received an e-mail from Alex indicating he found the testpoint problem and fixed it today:

Quote from Alex: "After we swapped the frame builder computer it has reconfigured all device files and I needed to create some symlinks on /dev/ to make tpman work again. I test the testpoints and they do work now."

The PD Kiwamu removed from the Y table was TRY, which we still need.

My bad if he took that. By mistake I told him that was the one I installed on the table for the length measurement and we didn't need it anymore.

I'm going to ask Kiwamu if he can kindly put it back.

 I am going to put the PD back to the Y end table in this afternoon.

I put the TRY_PD back to the end table and aligned it. Now it seems to be working well.

I updated the IP address on the Cisco Linksys wireless N router, which we're using to keep megatron separated from the rest of the network.  I then went in and updated megatrons resolv.conf and host files.  It is now possible to ssh into megatron again from the control machines.

I have measured the arm visibilities.
I did not see any change since the last wiping. Our vacuum is not contaminating the cavity in the time scale of 2 months.
It is very good.

Arm visibility measurement ~ latest (Feb. 17, 2010)

Arm visibility measurement after the vent (Dec. 14, 2009)

Arm visibility measurement before the vent (Nov 10, 2009)

X Arm: 0.875 +/- 0.005
Y Arm: 0.869 +/- 0.006

[Jenne, Kiwamu, with moral support from Koji, and loads of advice from Steve and Bob]

New upgrade ITMX (ITMU03) has it's guiderod & standoff glued on, as step 1 toward hanging the ITMs.

Procedure:

1. Make sure you have everything ready.  This is long and complicated, but not really worth detail here.  Follow instructions in E970037 (SOS Assembly Spec), and get all the stuff in there.

2. Set optic in a 'ring stand', of which Bob has many, of many different sizes. They are cleaned and baked, and in the cleanroom cupboard on the bottom just behind the door. We used the one for 3" optics.  This lets you sit the optic down, and it only rests on the bevel on the outside, so no coated surface touches anything.

3. Drag wipe the first surface of the optic, using Isopropyl Alcohol.  We used the little syringes that had been cleaned for the Drag Wipe Event which happened in December, and got fresh Iso out of the bottle which was opened in Dec, and put it into a baked glass jar.  The drag wipe procedure was the same as for the December event, except the optic was flat on the bench, in the ring holder.

4. Turn the optic over.

5. Drag wipe the other surface.

6. Align the optic in the guiderod gluing fixture (Step 3 in Section 3.2.1: Applying Guide Rod and Wire Standoff of E970037).

7. Set guiderod and standoff (1 guiderod on one side, 1 standoff on the other, per instructions) against the side of the optic.

8.a.  Use a microscope mounted on a 3-axis micrometer base to help align the guiderod and standoff to the correct places on the optic (Steps 4-5 of Section 3.2.1).  This will be much easier now that we've done it once, but it took a looooooong time. 

8.b.  We put the optic in 180deg from the way we should, based on the direction of the wedge angle in the upgrade table layout (wedge angle stuff used a "Call a Friend" lifeline.  We talked to Koji.) The instructions say to put the guiderod and standoff "above" the scribe lines in the picture on Page 5 of E970037 - the picture has the arms of the fixture crossing over the scribe lines.  However, to make the optic hang correctly, we needed to put the guiderod and standoff below the scribe lines.  This will be true as long as the arrow scribe line (which marks the skinniest part of the optic, and points to the HR side) is closest to you when the optic is in the fixture, the fixture is laying on the table (not standing up on end) with the micrometer parts to your right.  We should put the other ITM into the fixture the other way, so that the arrow is on the far side, and then we'll glue the guiderod and standoff "above" the scribe lines.  Mostly this will be helpful so that we can glue in exactly the places the instructions want us to.

8.c.  The biggest help was getting a flashlight to help illuminate the scribe lines in the optic while trying to site them in the microscope.  If you don't do this, you're pretty much destined to failure, since the lights in the cleanroom aren't all that bright. 

8.d.  The micrometer mount we were able to find for the microscope has a max travel of 0.5", but the optic is ~1" thick.  To find the center of the optic for Step 5 in the guiderod and standoff alignment we had to measure smaller steps, such as bevel-to-end-of-scribe-line, and length-of-scribe-line then end-of-scribe-line-to-other-bevel.  Thankfully once we found the total thickness and calculated the center, we were able to measure once bevel-to-center. 

9. Apply glue to the guiderod and standoff.  We made sure to put this on the "down" side, which once the optic is hung, will be the top of the little rods.  This matches the instructions as to which side of the rods to apply the glue on.  The instructions do want the glue in the center of the rod though, but since we put the optic in the fixture the wrong way, we couldn't reach the center, so we glued the ends of the rods.  We will probably apply another tiny dab of glue on the center of the rod once it's out of the fixture, perhaps while the magnet assemblies are being glued.

10.  We didn't know if the airbake oven which Bob showed us to speed up the curing of our practice epoxy last night was clean enough for the ITM (he was gone by the time we got to that part), so for safety, we're leaving the optic on the flow bench with a foil tent (the foil is secured so there's no way it can blow and touch the optic).  This means that we'll need the full curing time of the epoxy, not half the time.  Maybe tomorrow he'll let us know that the oven is in fact okay, and we can warm it up for the morning.

The Vac pressure measured at P1 is at 2.5mTorr.  I expect we'll hit 3mTorr sometime this afternoon, at which point (according to Steve) the interlock will shut the shutter, and we won't have light in the IFO.  Anything which needs to happen with light in the IFO before Monday needs to happen fairly soon.

- ETMX/ETMY oplev paths renewed. The nominal gain for ETMY YAW was reversed as a steering mirror has been put.
- Oplevs/QPDs cenrtered except for the MCT QPD.
- SUS snapshots updated
- QPD/Aligment screenshots taken

40m Wiki: Preparation for power supply stop

Jenne and kiwamu

We have glued the dumbbells to the magnets that will be used for the ITMs

We made two sets of glued pair of the dumbbell and the magnet ( one set means 6 pairs of the dumbbell and the magnet. Therefore in total we got 12 pairs. )

You can see the detailed procedure we did on the LIGO document E990196.

Actually we performed one different thing from the documented procedure;

we made scratch lines on the surface of the both dumbbells and magnets by a razor blade.

According to Steve and Bod, these scratch make the strength of the glues stronger.

Now the dumbbell-magnet pairs are on the flow bench in the clean room, and supported by a fixture Betsy sent us.

- -  notes

On the bench the left set is composed by magnets of 244 +/- 3 Gauss and the right set is 255 +/- 3 Gauss.

Koji and kiwamu

The existing optics on the ETMX/ETMY end table were rearranged in this morning.

The main things we have done are -

1. relocation of the optical levers for ETMs ( as mentioned in koji's entry )

This relocation can make a space so that we can setup the green locking stuffs.

The optical path of the green locking is planed to start from the right top corner on the table, therefore we had to relocate the oplevs toward the center of the table.

2. relocation of the lens just before the tube

Because we are going to shoot the green beam into the arm cavity, we don't want to have any undesired lenses before the cavity.

For this reason we changed the position of the lens, it was standing just in front of the tube, now it's standing on the left side of the big mirror standing center top.

Since we did not find a significant change in its the spot size of the transmitted light, we did not change the position of all the TRANS_MON_PDs and its mirrors. And they are now well aligned.

Attachment1: ETMX end table

Attachment2: ETMY end table

• Turned on the RAID attached to linux1 (its our /cvs/cds disk)
  
• Turned on linux1 (it needed a keyboard and monitor in order to be happy - no fsck required)
  
• Turned on nodus (and started ELOG) + all the control room machines
  
• Turned on B/W monitors
  
• Untaped fridge
  

• Found several things OFF which were not listed in the Wiki...
  
• Turned ON the 2 big isolation transformers (next to Steve's desk and under the printer). These supply all of the CDS racks inside.
  
• ~75% of the power strips were OFF in the CDS racks ?? I turned on as many as I could find (except the OMC).
  
• Switched on and keyed on all of the FE and SLOW crates in no particular order. Some of the fans sound bad, but otherwise OK.
  
• Turned on all of the Sorensens that are labeled.
  
• Turned ON the linear supplies close to the LSC rack.
  
• ON the Marconis - set them according to the labels on them (probably out-dated).
  
• After restoring power to the PSL enclosure (via the Isolation Transformer under the printer) turned the Variac ON and HEPA on full speed.
  
• Plugged in the PSs for the video quads. Restored the Video MUX settings - looks like we forgot to save the correct settings for this guy...
  

PSL

Autoburts have not been working since the network changeover last Thursday.

Last snapshot was around noon on Feb 11...  

It turns out this happened when the IP address got switched from 131.... to 192.... Here's the horrible little piece of perl code which was failing:

$command = "/usr/sbin/ifconfig -a > $temp";
   system($command);

   open(TEMP,$temp) || die "Cannot open file $temp\n";
   $site = "undefined";
   #                                                                                                     
   # this is a horrible way to determine site location                                                   
   while ($line = <TEMP>) {
     if ($line =~ /10\.1\./) {
       $site = "lho";
     } elsif ($line =~ /10\.100\./) {
       $site = "llo";
     } elsif ($line =~ /192\.168\./) {
       $site = "40m";
     }
   }
   if ($site eq "undefined") {
     die "Cannot Determine Which LIGO Observatory this is\n";


I've now put in the correct numbers for the 40m...and its now working as before. I also re-remembered how the autoburt works:

1) op340m has a line in its crontab to run /cvs/cds/caltech/burt/autoburt/burt.cron (I've changed this to now run at 7 minutes after the hour instead of at the start of the hour).

2) burt.cron runs /cvs/cds/scripts/autoburt.pl (it was using a perl from 1999 to run this - I've now changed it to use the perl 5.8 from 2002 which was already in the path).

3) autoburt.pl looks through every directory in 'target' and tries to do a burt of its .req file.

Oh, and it looks like Joe has fixed the bug where only op440m could ssh into op340m by editing the host.allow or host.deny file (+1 point for Joe).

But he forgot to elog it (-1 point for Joe).®

I knew there was going to be a script somewhere with a hard coded IP address.  My fault for missing it.  However, in regards to the removal of op340m's host.deny file, I did elog it here.  Item number 5.

This work happened on Friday, after Nodus and the elog went down....

[Jenne, Kiwamu]

The guiderod and standoff for ITMY were epoxied, and left drying over the weekend on the flow bench under a foil tent.  The flow bench was off for the weekend, so we made tents which hopefully didn't have any place for dust to get in and settle on the mirrors.

There is a small chance that there will be a problem with glue on the arm of the fixture holding the guiderod to the optic.  Kiwamu and I examined it, and hopefully it won't stick.  We'll check it out this afternoon when we start getting ready for gluing magnets onto optics this afternoon.

Turned on the power supply for the oplev lasers.
Turned on the power of the aux NPRO.
Turned on some of the Sorensen at 1X1.
Fixed the thermal output to round -4.0.
Locked PMC / MZ.

Waiting for the computers recovering.

I fixed the JetStor 416S raid array IP address by plugging in my laptop to its ethernet port, setting my IP to be on the same subnet, and using the web interface.  (After finally tracking down the password, it has been placed in the usual place).

After this change, I powered up the fb40m2 machine and reboot the fb40m machine. This seems to have made all the associated lights green.

Data viewer is working such that is recording from the point I fixed the JetStor raid array and did the fb40m reboot.  It also can go back in time before the IP switch over.

Even after bringing up the fb40m, I was unable to get the front ends to come up, as they would error out with an RFM problem.

We proceeded to reboot everything I could get my hands on, although its likely it was daqawg and daqctrl which were the issue, as on the C0DAQ_DETAIL screen their status had been showing as 0xbad, but after the reboot showed up as 0x0.  They had originally come up before the frame builder had been fixed, so this might have been the culprit.  In the course of rebooting, I also found c1omc and c1lsc had been turned off as well, and turned them on.

After this set of reboots, we're now able to bring the front ends up one by one.

While working on c1omc, I created a .cshrc file in the controls home directory, and had it source the cshrc.40m file so that useful shortcuts like "target" and "c" work, among other things.  I also fixed the resolv.conf file so that it correctly uses linux1 as its name server (speeding up ssh login times).

[Kiwamu, Jenne]

The magnets + dumbbell standoffs have been glued to ITMX.  We're waiting overnight for them to dry. 

Since I broke one of the magnet + dumbbells on the ITMY set, we've glued another dumbbell to the 6th magnet, and it should be ready for us to glue to ITMY tomorrow, once ITMX is dry and out of the fixture.  This doesn't put us behind schedule at all, so that's good.

We had been concerned that there might be a problem with the arm of the guiderod fixture being glued to ITMY, but it was fine after all.  Everything is going smoothly so far.

[Zach, Mott]

Zach and Mott are almost prepared to start cutting the viton for the earthquake stops.  We need 2 full sets by Wednesday morning, when we expect to begin hanging the ITMs.

Work on 22nd Monday:

[MC recovery]

- Tried to lock MC after the computer recovery by Joe.
- A lot of higher modes. I can touch the input periscope or the MC mirrors.
- First tried to align the MC mirrors. MC1 was aligned against the MC REFL PD. MC2/3 was aligned to maximize the transmitted power.
- After the alignment, I got the MC Trans Sum ~8V. Also I saw the flashing of the arm cavities. I decided to take this alignment although the beam looks little bit clipped by the faraday.

[IFO alignment recovery]

- Aligned the arms for TEM00 manually.
- Arm alignment script seems not working now. This could come from the move of the end QPDs
- PRMI/DRMI were aligned. All alignment values saved.

[Low power MC]

[Optical config]

- I fixed the MCT CCD camera. It is quite useful to align the MC.

- Inserted HWP+Cube PBS+HWP combo in the MC incident path.
- First HWP and PBS adjust the light power. The second HWP is fixed at 342deg such that it restores the poralization to S.
- The incident power was measured by the SCIENTECH power meter. Offset of 3mW was subtracted in the table below.

- HWP1 85deg is the nominal.

- I needed to touch the steering mirror (indicated by the picture) to obtain TEM00.
  The alignment of the HWPs and the cube PBS didn't change the mode. Thermal lense of the cube?

- I could not lock the MC with the incident power below 100mW. So the BS in the MC REFL path was replaced by a total reflector (Y1-45S).
- This increased the power on the MC REFL PD x10 of the previous. NOW WE ARE CONSTRAINED BETWEEN 81deg~90deg. DON'T ROTATE FURTHER!
- The original BS was stored on the AP table as shown in the picture.
- This total reflector disabled the MC WFS QPDs. We can't use them.

[Lock of the MC with 20mW incident]
- Disable the MC autolocker.
- Disable the MC WFS.
- Run
  /cvs/cds/caltech/scripts/MC/mcloopson
- Turn on the MCL servo.
- Set the MCL gain to 1.5 (it was nominally 0.3 for the high power)
- Just wait until lock.

[Gain boost after the lock] ...If you like to have more gain
- There was almost no room to increase the MCL gain.
- MC_REFL_GAIN can be increased from +6dB to +20dB
  ezcawrite "C1:IOO-MC_REFL_GAIN" 20
- MC_VCO_GAIN can be increased from -3dB to +2dB
  ezcawrite "C1:IOO-MC_VCO_GAIN" 2
- Crank the FSS gains
  ezcawrite C1:PSL-FSS_MGAIN `ezcaread -n C1:PSL-STAT_FSS_NOM_C_GAIN`
  ezcawrite C1:PSL-FSS_FASTGAIN `ezcaread -n C1:PSL-STAT_FSS_NOM_F_GAIN`

[If lock is lost]
- Run
  /cvs/cds/caltech/scripts/MC/mcdown

Our janitor dropped one 48" long  fluorescent tube on the top cover of ETMX-isct. This accident made glasses fly all over the place.

He cleaned up nicely, but please beware of small glass pieces around ETMX chamber.

We did not clean up on the table in order to reserve oplev and green ITMX pointing alignment.

Plot below shows that the alignment was not effected.

Most of the RFM went red this morning. I took the nuclear option and it seemed to be recovered.

Since we're going to open the MC1 tank tomorrow, I've moved the MC1 accelerometers and the Guralp over to underneath MC2 for the vent.  I'll reconnect them later.

[Steve, Bob, Joe, Zach, Alberto, Kiwamu, Koji]

We opened the OMC-IMC access connector, ITMX North door, and ITMY West door.
We worked from 9:30-11:00.
The work was quite smooth thanks to the nice preparation of Steve as usual.

Thank the team for the great work!

This is going to be a laundry list of the mile markers achieved so far:

* Guiderod and wire standoff glued to each ITMX and ITMY

* Magnets glued to dumbbells (4 sets done now).  ITMX has 244 +- 3 Gauss, ITMY has 255 +- 3 Gauss.  The 2 sets for SRM and PRM are 255 +- 3 G and 264 +- 3 G.  I don't know which set will go with which optic yet.

* Magnets glued to ITMX.  There were some complications removing the optic from the magnet gluing fixture.  The way the optic is left with the glue to dry overnight is with "pickle picker" type grippers holding the magnets to the optic.  After the epoxy had cured, Kiwamu and I took the grippers off, in preparation to remove the optic from the fixture.  The side magnet (thankfully the side where we won't have an OSEM) and dumbbell assembly snapped off.  Also, on the UL magnet, the magnet came off of the dumbbell (the dumbbell was still glued to the glass).  We left the optic in the fixture (to maintain the original alignment), and used one of the grippers to glue the magnet back to the UL dumbbell.  The gripper in the fixture has very little slop in where it places the magnet/dumbbell, so the magnet was reglued with very good axial alignment.  Since after the side magnet+dumbbell came off the glass, the 2 broke apart, we did not glue them back on to the optic.  They were reattached, so that we can in the future put the extra side magnet on, but I don't think that will be necessary, since we already know which side the OSEM will be on.

* Magnets glued to ITMY.  This happened today, so it's drying overnight.  Hopefully the grippers won't be sticky and jerky like last time when we were removing them from the fixture, so hopefully we won't lose any magnets when I take the optic out of the fixture.

* ITMX has been placed in its suspension cage.  The first step, before getting out the wire, is to set the optic on the bottom EQ stops, and get the correct height and get the optic leveled, to make things easier once the wire is in place.  Koji and I did this step, and then we clamped all of the EQ stops in place to leave it for the night.

* The HeNe laser has been leveled, to a beam height of 5.5inches, in preparation for the final leveling of the optics, beginning tomorrow.  The QPD with the XY decoder is also in place at the 5.5 inch height for the op lev readout.  The game plan is to leave this set up for the entire time that we're hanging optics.  This is kind of a pain to set up, but now that it's there, it can stay out of the way huddled on the side of the flow bench table, ready for whenever we get the ETMs in, and the recoated PRM. 

* Koji and Steve got the ITMX OSEMs from in the vacuum, and they're ready for the hanging and balancing of the optic tomorrow.  Also, they got out the satellite box, and ran the crazy-long cable to control the OSEMs while they're on the flow bench in the clean room.

Koji and I discovered a problem with the small EQ stops, which will be used in all of the SOS suspensions for the bottom EQ stops.  They're too big.  :(  The original document (D970312-A-D) describing the size for these screws was drawn in 1997, and it calls for 4-40 screws.  The updated drawing, from 2000 (D970312-B-D) calls for 6-32 screws.  I naively trusted that updated meant updated, and ordered and prepared 6-32 screws for the bottom EQ stops for all of the SOSes.  Unfortunately, the suspension towers that we have are tapped for 4-40.  Thumbs down to that.  We have a bunch of vented 4-40 screws in the clean room cabinets, which I can drill, and have Bob rebake, so that Zach and Mott can make viton inserts for them, but that will be a future enhancement.  For tonight, Koji and I put in bare vented 4-40 screws from the clean room supply of pre-baked screws.  This is consistent with the optics in our chambers having bare screws for the bottom EQ stops, although it might be nicer to have cushy viton for emergencies when the wire might snap.  The real moral of this story is: don't trust the drawings.  They're good for guidelines, but I should have confirmed that everything fit and was the correct size.

Last night I worked on the MC incident beam such that we can hit the center of the MC mirrors.

Steve and I checked the incident beam on MC1. We found the beam is ~5mm south.
This was not too critical but it is better to be realigned. I moved the steering mirror on the OMC
table (in vac). We kept the MC resonated. After the maximization of the resonance, I realigned the
MC1 and MC3 such that the resonance in dominated by TEM00.

Jenne, Kiwamu, and I then closed the light door on to the OMC/IMC.

I will make more detailed entry with photos in order to explain what and how I did.

Since Rosalba wanted to update ~500 packages, I let it do it. This, of course, stopped the X server from running. I downloaded and installed the newest Nvidia driver and its mostly OK.

The main problem with the auto-update on our workstations is that we've updated some packages by hand; i.e. not using the standard CentOS yum. So that means that the auto-update doesn't work right. From now on, if you want to install a fancier package than what CentOS distributes, you should commit to handle the system maintenance for these workstations for the future. Its not that we can't have new programs, we just have to pay the price.

At 23:45 PST, I also started a slow triangle wave on the AOM drive amplitude. This is to see if there's a response in the FSS-FAST which might imply a coupling from intensity noise to frequency noise via absorbed power and the dn/dT effect in the coatings.

Its a 93 second period triangle modulating the RC power from 100% down to 50%.

The overnight triangle wave I ran on the AOM drive turns out to have produced no signal in the FAST feedback to the PZT.

The input power to the cavity was ~10 mW (I'm totally guessing). The peak-peak amplitude of the triangle wave was 50% of the total power.

The spectral density of the fast signal at the fundamental frequency (~7.9 mHz) is ~0.08 V/rHz. The FAST calibration is ~5 MHz/V. So, since we

see no signal, we can place an upper limit on the amount of frequency shift = (5 MHz/V) * (0.08 V/rHz) * sqrt(0.0001 Hz) = 4 kHz.

Roughly this means that the RIN -> Hz coefficient must be less than 4 kHz / 5 mW or ~ 1 Hz/uW.

For comparison, the paper on reference cavities by the Hansch group lists a coefficient of ~50 Hz/uW. However, they have a finesse of 400000

while we only have a finesse of 8000-10000. So our null result means that our RC mirrors' absorption is perhaps less than theirs. Another possibility

is that their coating design has a higher thermo-optic coefficient. This is possible, since they probably have much lower transmission mirrors. It would be

interesting to know how the DC thermo-optic coefficient scales with transmission for the standard HR coating designs.

In order to block stray beams, I have put some beam dumps and razor blades on the PSL  table.

There were three undesired spots in total. I found two spots on the south side door of the PSL room, close to Mach-Zehnder.

Another spots was on the middle of the north door. Now they all are blocked successfully.

Jenne and Koji

We successfully hung ITMX on the SOS. Side magnet is ~2mm off from the center of the OSEM. ITMX aligned using the QPD. The OSEMs changes the alignment. It looks that something magnetic is inside the OSEM PD or LED.

Reguled ITMY side magnet.

Cleaned up the lab for the safety inspection.

 Some details on the side magnet situation from today: 

To glue the magnets+dumbbells to the optics, we use the magnet-dumbbell gluing fixture.  This fixture is supposed to have teflon 'pads' for the optic to sit on while you align it in the fixture, however the fixture which we received from MIT (it's Betsy's....but it came via MIT) only had one of the 4 teflon pads. 

Kiwamu and I decided (last week, when we first glued ITMX's magnets) that it would be bad news to let the AR face of the optic sit on bare metal, so we fashioned up some teflon pads using stock in a cabinet down the Yarm.  We were focused on thinking about the face magnets, and didn't think about how the thickness of the teflon affected the placement of the side magnet.  We chose some teflon that was too thin by ~1mm, so the optic sat too low in the fixture, resulting in the side magnet being glued too close to the HR side of the optic (this is all along the Z - axis, where Z is the direction of beam propagation). 

Why it ended up being 2mm off instead of only 1mm I don't really have an explanation for, other than perhaps tightening the set screws to hold the optic (by the barrel) in the fixture pushes the optic up.  I observed this happening when I didn't put any effort into keeping the optic flat on the teflon pads, but I thought that I made sure the optic was seated nicely in the fixture before starting to glue.  When I glued the new ITMY side magnet tonight I tried to make sure that the optic was seated nicely in the fixture.  We'll see what happens.

Before gluing the new ITMY side magnet (and now it's set for all future magnet gluings....), I found 4 teflon pads of all the correct thickness.  It turns out that we have a magnet gluing fixture of our own, which I found in the cabinets in the clean room.  This fixture had all 4 teflon pads, so I stole them and put them into the one that we're using for this round of upgrade / suspension hangings.  The height of all future side magnets should be correct. The thickness of the pads in the 'spare' fixture matched the one which came with the fixture from MIT as closely as I could feel by putting them on the same flat surface next to each other and feeling if there was a step. 

A side note about this magnet gluing fixture that I found:  It has the word "TOP" etched into it, to prevent exactly my problem with the ITMY side magnets in the first place.  Unfortunately the threads for the set screws which hold the optic are shot (or something is funny with them), so we can't just use this fixture. 

Gluing notes regarding the standoffs and guiderods:

There's more glue than I'd like on the guiderods / standoff for ITMX.  The glue was starting to get a little tacky when I glued the standoff in place after we balanced the optic, so it was hard to get it in the right place.  I'm confident we have a good epoxy contact, and we don't have much glue that I think it'll be a big problem.  Certainly I'll be a lot better at manuvering my glue-stick a.k.a skinny piece of wire around the suspension tower to get to the standoff for the rest of the optics that we're hanging, and I won't have glued something like ITMY side magnet immediately beforehand, which took enough time that the glue started to get tacky (not very tacky, just barely noticeably tacky).

I'd say that most gluing activities should be completed within ~10-15min of mixing the glue, after spending ~2min stirring to make sure it's nice and uniform.  It doesn't dry fast enough to be a huge rush, but you should get right on the gluing once the epoxy has been mixed. 

This is a simple representation of the schematic:

          gnd
#          |
#          Cw2
#          |
#          n23
#          |
#          Lw2
#          |
#           n22
#          |
#          Rw2                 
#                 |                   |\             
#           n2- - - C2 - n3 -  - -  - |  \           
#            |    |      |   |        |4106>-- n5 - Rs -- no
# iinput    Rd   L1     L2 R24    n6- |  /     |           |
#      nin - |    |      |   |    |   |/       |         Rload     
#           Cd   n7     R22 gnd   |            |           |           
#            |    |      |        | - - - R8 - -          gnd               
#           gnd  R1     gnd      R7  
#                 |               |
#         gnd               gnd
#                  
#
#

I chose the values of the components in a realistic way, that is using part available from Coilcraft or Digikey.

Using LISO I simulated the Tranfer Function and the noise of the circuit.

I'm attaching the results.

I'll post the 55MHz rfpd later.

[Koji, Jenne]

First, the easy story:  SRM got it's guiderod & standoff glued on this evening.  It will be ready for magnets (assuming everything is sorted out....see below) as early as tomorrow.  We can also begin to glue PRM guiderods as early as tomorrow.

The magnet story is not as short.....

Problem: ITMX and ITMY's side magnets are not glued in the correct places along the z-axis of the optic (z-axis as in beam propagation direction). 

ITMX (as reported the other day) has the side magnet placement off by ~2mm.  ITMX side was glued using the magnet fixture from MIT and the teflon pads that Kiwamu and I improvised.

It was determined that the improvised teflon pads were too thin (maybe about 1m thick), so I took those out, and replaced them with the teflon pads stolen from the 40m's magnet gluing fixture.   (The teflon pad from the MIT fixture and the ones from the MIT fixture are the same within my measuring ability using a flat surface and feeling for a step between them.  I haven't yet measured with calipers the MIT pad thickness).  The pads from the 40m fixture, which were used in the MIT fixture to glue ITMY side last night were measured to be ~1.7mm thick.

Today when Koji hung ITMY, he discovered that the side magnet is off by ~1mm.  This improvement is consistent with the switching of the teflon pads to the ones from the 40m fixture.

We compared the 40m fixture with the one from MIT, and it looks like the distance from the edge of where the optic should sit to the center of the hole for the side magnet is different by ~1.1mm.  This explains the remaining ~1mm that ITMY is off by. 

We should put the teflon pads back into the 40m fixture, and only use that one from now on, unless we find an easy way to make thicker teflon pads for the fixture we received from MIT.  (The pads that are in there are about the maximum thickness that will fit).  I'm going to use my thickness measurements of SRM (taken in the process of gluing the guiderods) to see what thickness of pads / what fixture we want to actually use, but I'm sure that the fixture we found in the 40m is correct.  We can't use this fixture however, until we get some clean 1/4-28 screws.  I've emailed Steve and Bob, so hopefully they'll have something for us by ~lunchtime tomorrow. 

The ITMX side magnet is so far off in the Z-direction that we'll have to remove it and reglue it in the correct position in order for the shadow sensor to do anything.  For ITMY, we'll check it out tomorrow, whether the magnet is in the LED beam at all or not.  If it's not blocking the LED beam enough, we'll have to remove and reglue it too. 

Why someone made 2 almost identical fixtures, with a 1mm height difference and different threads for the set screws, I don't know.  But I don't think whoever that person was can be my friend this week. 

oops, forgotten the third attachment...

here it is

I read a few datasheets of the C30642GH photodiode that we're going to use for the 11 and 55 MHz. Considering the  values listed for the resistance and the capacitance in what they define "typical conditions" (that is, specific values of bias voltage and DC photocurrent) I fixed Rd=25Ohms and Cd=175pF.

Then I picked the tunable components in the circuit so that we could adjust for the variability of those parameters.

Finally with LISO I simulated transfer functions and noise curves for both the 11 and the 55MHz photodiodes.

I'm attaching the results and the LISO source files.