Antiproton Lens Replacement

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Antiproton Lens Replacement

• Keith Gollwitzer
• Antiproton Source Department
• for the Experts and Mechanical Support Department
  Target Station Group

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Initial Failure at 1840 Friday Determined
problem in vault and not the power
supply Appeared as open circuit
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Lens change-out crew arrive, open vault, remove
module with lens/transformer assembly and
discover problem
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• Strip-line failure (1st time seen)
• Moved on to installing previously used 10mm-2
  lens (high gradient)
• 10mm-2 history
• Used 1 week in May07 before water leak caused
  transformer to fail
• Lens installed in a new transformer during
  shutdown07
• Used Oct-Dec07
• During Target change-out photograph showed
  tie-rod working its way out
• Tie-rod repaired early Jan08

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10mm-2 lens put upon module and connections
made Failed water circuit test (pressurized
gas) 2 pairs of 8ft tubes run though module
(provide water cooling for lens and transformer)
connect to brass block (patch panel) of
lens/transformer assembly. Depending upon brass
block, order of connection can make difference of
leak Could not disconnect one water tube
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Meeting to discuss options Repair 10mm-2 brass
block water tube connection vs installing low
gradient lens 32 Low gradient means a 12-15
loss of yield 8days low gradient 7days high
gradient Repair plan was chosen
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Water tube was forcibly removed from brass
block 10mm-2 lens/transformer assembly
un-installed from module New water tube
installed on module New brass block was taken
from another low gradient lens Brass block
swap-out performed on 10mm-2 Re-install 10mm-2
lens/transformer assembly to module Pressurize
gas test - still leak 10mm-2 lens/transformer
assembly un-installed from module Determine leak
on connection of line into lens -- tightened
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Upon moving lens/transformer assembly to prepare
for re-connection to module, hit a water
line Replaced water line Reconnect
lens/transformer assembly to module Passed water
circuit test!! HiPot of module
lens/transformer find 1mA _at_ 1500V New lens are
lt1µA _at_ 3000V Earlier HiPot of 10mm-2 was
reasonable Experts decided to install into vault
and pulse at low setting to see if can change
HiPot Power supply trip on load overcurrent
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Disconnected from power supply HiPot of module
lens/transformer find 1.7µA _at_ 3000V!! Vault
stripline HiPot is also fine Connect power
supply to pulse ground fault Problem getting
power supply to turn on with dummy load Movement
of control cards about get supply to pulse with
Back to original configurationable to pulse
dummy load Another HiPot of module
lens/transformer shows good Power supply
re-connected to lens/transformer
Pulsing!!! Will gradually bring up to operation
gradient and then put rest of shielding blocks
back. Should be stacking within a few hours