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SUS_Lab
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CRIME_Lab
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ENG_Labs
OptContFac
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WBEEShop
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40m Log |
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Wed Jul 27 15:03:02 2016, sisyphus, Metaphysics, SUS, Broken wire
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Wed Jul 27 16:56:47 2016, rana, Metaphysics, SUS, Broken wire
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Thu Jul 28 08:42:36 2016, Steve, Update, SUS, wire clamp
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Fri Jul 29 15:17:23 2016, Steve, Update, SUS, wire and clamping test
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Fri Jul 29 20:12:54 2016, gautam, Update, SUS, third time - no luck
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Mon Aug 1 14:09:20 2016, Steve, Update, SUS, third time - no luck
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Tue Aug 9 16:19:27 2016, Steve, Update, SUS, torque driver for wire clamp
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Wed Aug 10 15:34:24 2016, Steve, Update, SUS, 6 in-lbs torque driver for wire clamp screw
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Wed Aug 3 00:15:39 2016, gautam, Update, SUS, ETMX suspended
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Wed Aug 3 09:26:54 2016, Lydia, Update, SUS, ETMX suspended: photos 8x
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Thu Aug 4 03:14:39 2016, gautam, Update, SUS, ETMX suspended
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Fri Aug 5 02:17:10 2016, gautam, Update, SUS, ETMX Ruby Wire Standoff Ready for Gluing 8x
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Fri Aug 5 04:43:09 2016, Koji, Update, SUS, ETMX Ruby Wire Standoff Ready for Gluing
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Fri Aug 5 18:21:28 2016, gautam, Update, SUS, ETMX Ruby Wire Standoff GLUED 11x
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Sun Aug 7 14:53:39 2016, ericq , Update, SUS, ETMX Standoff gluing was successful 
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Tue Aug 9 00:44:43 2016, gautam , Update, SUS, ETMY patch-up
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Tue Aug 9 15:27:57 2016, gautam , Update, SUS, ETMY patch-up 
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Wed Aug 10 03:08:03 2016, gautam , Update, SUS, ETMY patch-up
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Wed Aug 10 23:45:03 2016, gautam , Update, SUS, ETMY re-suspended 7x
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Thu Aug 11 00:20:41 2016, Koji, Update, SUS, ETMY re-suspended
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Thu Aug 11 11:56:40 2016, gautam, Update, SUS, ETMY re-suspended
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Mon Aug 15 18:28:15 2016, gautam, Update, SUS, Air-bake preparation
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Tue Aug 16 08:04:49 2016, Steve, Update, SUS, ETMY had Aluminum bridge
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Tue Aug 16 21:54:27 2016, gautam, Update, SUS, Air-bake - IN PROGRESS
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Wed Aug 17 08:47:43 2016, ericq, Update, SUS, Air-bake finished
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Wed Aug 17 23:00:57 2016, gautam, Update, SUS, Air-bake of towers
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Thu Aug 18 08:17:16 2016, Steve, Update, SUS, wire clamping preparation
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Thu Aug 18 14:14:20 2016, gautam, Update, SUS, Air-bake of towers - finished
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Fri Aug 19 22:51:12 2016, gautam, Update, SUS, ETMs first-contacted
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Sun Aug 21 16:23:05 2016, gautam, Update, SUS, ETMX suspended
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Mon Aug 22 13:06:11 2016, gautam, Update, SUS, ETMY suspended
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Mon Aug 22 18:04:24 2016, gautam, Update, SUS, ETMY OSEMs inserted
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Tue Aug 23 19:35:38 2016, gautam, Update, SUS, ETMY back in IFO 10x
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Thu Aug 25 21:11:43 2016, gautam, Update, SUS, ETMY back in IFO
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Fri Aug 26 11:35:44 2016, gautam, Update, SUS, ETMY UL sensor problematic  
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Fri Aug 26 14:05:38 2016, Steve, Update, SUS, ETMY UL sensor problematic
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Fri Aug 26 14:09:46 2016, ericq, Update, SUS, ETMY UL sensor problematic
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Sun Aug 28 21:40:11 2016, gautam, Update, SUS, ETMY UL sensor problematic
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Mon Aug 29 09:37:05 2016, gautam, Update, SUS, ETMY UL sensor problematic
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Mon Aug 29 14:42:06 2016, gautam, Update, SUS, ETMY Satellite box diagnostics 
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Fri Aug 26 17:48:14 2016, gautam, Update, SUS, bounce mode coupling reduction
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Mon Aug 29 21:53:14 2016, Lydia, Update, SUS, ETMY bounce mode coupling 
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Tue Aug 30 20:26:36 2016, gautam, Update, SUS, ITMY installed  
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Wed Aug 31 18:07:43 2016, Johannes, Update, SUS, ITMY free swinging
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Wed Aug 31 22:09:18 2016, gautam, Update, SUS, Y arm locked to Green
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Thu Sep 1 08:30:24 2016, Steve, Update, SUS, ITMY_UL is sick 
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Tue Sep 6 20:30:56 2016, rana, Update, SUS, ITMY_UL is sick
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Tue Sep 13 11:00:59 2016, Lydia, Update, SUS, ETMY UL glitch returned
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Thu Sep 1 19:59:22 2016, Johannes, Update, SUS, IR mode flashes in Y arm
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Fri Sep 2 21:09:08 2016, gautam, Update, SUS, Y arm locked in air 
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Tue Sep 6 20:45:14 2016, gautam, Update, SUS, X arm test masses back in chamber   
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Thu Sep 8 22:12:36 2016, gautam, Update, SUS, X arm in place, locked to green, IR flashes visible
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Fri Sep 9 17:50:02 2016, gautam, Update, SUS, Heavy doors on BS-PRM, ETMY chambers
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Sat Sep 10 14:26:01 2016, rana, Update, General, PRM SRM alignment
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Mon Sep 12 17:15:22 2016, Johannes, Update, General, PRM SRM alignment 
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Thu Sep 1 19:18:14 2016, Johannes, Update, SUS, ITMX and ETMX preemptive table leveling 8x
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Fri Sep 2 21:15:53 2016, gautam, Update, SUS, ITMX and ETMX preemptive table leveling
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Thu Sep 1 15:43:16 2016, rana, Update, SUS, OSEM adjustments
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Mon Sep 5 19:57:24 2016, Osamu, Update, SUS, OSEM adjustments
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Message ID: 12452
Entry time: Mon Aug 29 21:53:14 2016
In reply to: 12448
Reply to this: 12455
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Author: |
Lydia |
Type: |
Update |
Category: |
SUS |
Subject: |
ETMY bounce mode coupling |
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[gautam, johannes, lydia]
We decided to try some different approaches on minimizing the ETMY bounce coupling today, since the peak height in the previously attched spectrum was higher than the previously recorded levels in 2011 for all but the LR OSEM.
- We recoreded a coarse reference spectrum with the light door off and the HEPA filter on.
- We attempted to match UL, UR and LL orientation to their apparent position in photos takes before the OSEMs were initially removed. We found that every OSEM showed a stronger bounce coupling, including those that had not been moved. We repeated the spectrum a few times, damping the optic and then turning the damping back off between each data set. The effect persisted, so we decided to move them back to where they started today (the final posiitons of our earlier optimization attempt).
- The peaks returned to approximately their reference levels for all except LL. UL was still the worst overall, so we attempted to more finely tune its angle without success: we saw increases in the peak height in both directions again (when turned approx. 3-4 degrees).
- We then turned the UL OSEM by 90 degrees. (See Attachment 1). Surprisingly, the 16.4 Hz peak height was greatly reduced (by a factor of 7-9). We took another spectrum to confirm and the peak was significantly lower than the reference yet again. We decided to leave the OSEM in this configuration in order to take a finer spectrum (See Attachment 2). However, this means that while the magnet looks well centered in the OSEM, the sideways range of motion is reduced and there are no earthquake stops preventing string side to side swings, so care should be taken in the ETMY chamber.
- Before starting, we had discussed a possilbe mechanism for bounce coupling that could potentially be minimized by turning the OSEM so that the nominal beam direction was horizontal. This would be possible if the beam of light inside the OSEM were directed toward the front or back, i.e. if it had some component parallel to the POS axis. Then, if the component of the beam in the plane of the optic's surface is oriented vertically, the bounce mode will move the edge of the magnet's shadow in and out of the center of the beam, allowing for strong coupling (proportional to the size of the angle). Turning the OSEM by 90 degrees would eliminate this kind of coupling.
- It's also true that (regardless of the mechanism) minimizing bounce couling for an OSEM maximizes the side coupling. The side coupling values of the pre-vent diagonalization matrices might be useful to compare to what we see now, to find out if the minimization we do in fact increases the side coupling (if not, maybe we are not truly minimizing the bounce coupling but observing some other effect, or our measurement method is too inconsistent.) Thoughts on this are welcome.
- Now that this improvement has been found, we should do a more thorough investigation to see where the true optimum position is (no small steps have been taken around this new position, and the minimum could also be at some angle in between).
- In the interest of finishing the vent, should we try to find out exactly why the optimal angles seem so different than expected, or should we just try to minimize as best we can and move on to setting up the Y arm cavity?
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