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Message ID: 183     Entry time: Thursday, November 05, 2015, 17:07
Author: Isaac Earle 
Category: Repair 
Type: Target 2 
Specific: Target 
Subject: T2-MK1 Profile Monitor Repair and Pos'n 3 Target Removal 

The following work was performed on the T2-MK1 target.  The profile monitor and monitor cage on this target were damaged in January 2013, See E-Log #68

Oct 23:
- T2-MK1 target moved from storage pit hole #4 to the hot cell (field measurement was not possible because the pole monitor had issues
- Position 2 and 3 targets photographed (see attached)
- Position 3 target (10cm Be) removed.  This target had accumulated 11.5 months of beam time.  Maximum for T2 targets is 12 months according to new schedule.

Oct 26:
- Position 3 plugged
- Profile monitor cage inspected and photographed. The cage (TBP0106D) and aluminum frame (TBP0101C) were both noticeably damaged (see photos)
- Attempted to insert dummy cassette, went in smoothly
- Moved target ladder through all positions, moves smoothly, micro-switches ok, potentiometer ok
- Motor drive coupling inspected - no issues
- Actuated monitor in and out: traveled fairly smoothly, 40psi required to insert, 20psi to pull back out
- Dummy cassette removed, real replacement cassette inserted (went smoothly)
- Horizontal wires inspected w/ Nikon level, found to be crooked

Oct 27:
- Cassette frame nuts (TBP0108C-2) loosened and monitor frame adjusted until horizontal wires horizontal, nuts re-tightened and torqued
- Vertical and horizontal measurements of profile monitor position measured - All within 1-2mm of previous measurements in 2010
- Although some physical damage to frame is visible it still positions monitor in correct location and seems to be fully functional, therefore will use if electrical is ok

Oct 28:
- Electrical check performed on profile monitor by Mike Russell
- All 26 wires visible.  Screenshot of scope taken (see attached)
- Moved to position 5 to stretch bellows, and air left running through target overnight to dry

Oct 29:
- Cold trap filled with LN2, pumping with new leak detector started
- Test port at E-1 Torr range after 30s, E-2 after 1.5mins, E-3 range after 3mins, 0.0E-10 torrL/s leak rate after ~10mins, TP at <1.0E-3Torr after ~15mins
- Leak check performed with 3psi helium applied w/ ~0.5s bursts at all target locations, bellows, top of vac flange, and Hansen fittings
- Small leak found at left bellows lower weld (expect is negligible for water use), no response from all target locations (see attached scan of leak check notes), deemed water leak tight

Nov 3:
- Plumb bob measurements taken
- Vertical and horizontal measurements of Pos'n 2 target taken
- Target ladder moved to position 0, profile monitor secured in IN position to prevent damage during move

Nov 5:
- Target returned to storage pit hole #4
- Field of 53mSv/hr measured at ~0.3m (attempted 0.5m measurement, but was a little close)

 

The T2-MK1 target is now fully functional and ready for use.  The 10cm Be target in position 2 has not seen beam.

Note that the target window welds show some uneveness (see photos), but not expected to affect performance b/c leak tight.  The elevations sheet will be updated and filed in the T2 Binder in the Meson Hall HC Lab Office.


 

Attachment 1: damage_to_cage_frame.JPG  3.359 MB  | Show | Hide all
Attachment 2: damage_to_prof_mon_cage.JPG  2.814 MB  | Show | Hide all
Attachment 3: posn_2_entrance_1.JPG  2.657 MB  | Show | Hide all
Attachment 4: posn_2_exit_1.JPG  2.516 MB  | Show | Hide all
Attachment 5: posn_3_entrance_1.JPG  2.767 MB  | Show | Hide all
Attachment 6: posn_3_exit_1.JPG  2.767 MB  | Show | Hide all
Attachment 7: T2_MK1_target_with_a_new_profile_monitor_(oct_28_2015_by_mike_russell).JPG  104 kB  | Show | Hide all
Attachment 8: T2MK1_leak_check_notes_-_nov_2015.jpg  227 kB  | Show | Hide all
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