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40m Log |
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Tue Jan 15 10:52:38 2019, gautam, Update, SUS, EY door opened
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Tue Jan 15 15:49:47 2019, gautam, Update, SUS, EY door opened
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Sat Jan 19 15:33:18 2019, gautam, Update, SUS, ETMY OSEMs faulty 
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Tue Jan 22 20:36:53 2019, gautam, Update, SUS, ETMY OSEMs faulty
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Wed Jan 23 12:39:18 2019, gautam, Update, SUS, EY chamber work 6x
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Wed Jan 23 23:12:44 2019, gautam, Update, SUS, Prep for FC cleaning
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Thu Jan 24 15:32:31 2019, gautam, Update, SUS, Y arm cavity side first contact applied 
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Tue Jan 29 22:12:40 2019, gautam, Update, SUS, Alignment prep
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Wed Jan 30 11:54:24 2019, gautam, Update, SUS, More alignment prep 
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Wed Jan 30 19:25:40 2019, gautam, Update, SUS, Xarm cavity alignment 
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Fri Feb 1 01:24:06 2019, gautam, Update, SUS, Almost ready for pumpdown tomorrow
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Fri Feb 1 13:16:50 2019, gautam, Update, SUS, Pumpdown 83 underway
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Fri Feb 1 21:52:57 2019, gautam, Update, SUS, Pumpdown 83 underway
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Fri Feb 1 14:44:14 2019, gautam, Update, SUS, Y arm FC cleaning and reinstall  
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Wed Jan 16 16:25:25 2019, gautam, Update, SUS, Yarm locked
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Fri Jan 18 21:34:18 2019, gautam, Update, SUS, Unused optic on EY table
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Sat Jan 19 05:07:45 2019, Koji, Update, SUS, Unused optic on EY table
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Message ID: 14401
Entry time: Tue Jan 15 15:49:47 2019
In reply to: 14399
Reply to this: 14409
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Author: |
gautam |
Type: |
Update |
Category: |
SUS |
Subject: |
EY door opened |
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While restoring OSEMs on ETMY, I noticed that the open voltages for the UR and LL OSEMs had significantly (>30%) changed from their values from ~2 years ago. The fact that it only occurred in 2 coils seemed to rule out gradual wear and tear, so I looked up the trends from Nov 25 - Nov 28 (Sundance visited on Nov 26 which is when we removed the cage). Not surprisingly, these are the exact two OSEMs that show a decrease in sensor voltage when the OSEMs were pulled out. I suspect that when I placed them in their little Al foil boats, I shorted out some contacts on the rear (this is reminiscent of the problem we had on PRM in 2016). I hope the problem is with the current buffer IC in the satellite box and not the physical diode, I'll test with the tester box and evaluate the problem further.
Chamber work by Chub and gautam:
- Table leveling was checked with a clean spirit level
- Leveling was substantially off in two orthogonal directions, along the beam axis as well as perpendicular to it.
- We moved almost all the weights available on the table.
- Managed to get the leveling correct to within 1 tick on the level.
- We are not too worried about this for now, the final leveling will be after heater repositioning, ETMY cleaning etc.
- ETMY OSEM re-insertion
- OSEMs were re-inserted till their mean voltage was ~ half the open values.
- Local damping seems to work just fine.
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