HCAL SOURCE SYSTEMS

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HCAL SOURCE SYSTEMS

• SOURCE SYSTEMS STATUS
• Virgil Barnes
• Purdue University
• CMS HCAL, FIU Miami, February 26-26, 2005

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HCAL SOURCE SYSTEMS

• Fabrication of HE and HB air drivers is
  completed.
• HF PSDs (electric motor, Mod III) are completed,
  also some older TSDs have been refurbished. BUT
  
• Engineer Paul Debbins report has several
  potentially useful suggestions for improvements.
  Generally applicable to both air and electric
  source drivers. May help with reel friction
  and/or safely allowable extension force on wire.

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HCAL SOURCE SYSTEMS

• TSD retrofitted with
• Stainless steel slide sheet and
• Lower support wire
• 500 wire insertions
• 7.8 m plastic tube with tight coil at far end
• End of tube turnoff force set to 48 oz

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HB, HE SOURCE SYSTEMS

• Very little wear-product is seen. Substituting
  SS for the UHMWPE slide sheet seems to give lower
  and more consistent friction and, so far, no
  buildup of gummy spots on the slide sheet and no
  black powder fallling onto base plate.
• Lower support wire should, in principle, help
  protect the source wire from buckling during
  extension. Usual force limit 38-40 oz. We are
  testing with higher forces. Need to understand
  force limit vs. source wire life with the
  improved support wires.
• Extended testing will be done at Purdue.
• Very promising, so propose to retrofit these
  mods into several TSDs before shipping them to
  CERN next week for use at HB. Loading wires will
  require slightly more dexterity, but note the
  small retaining clip on the reel. Recent
  invention to make wire loading easier.
• Will look for phosphor bronze or other
  non-magnetic lower support wires for the air
  drivers in 4T field.

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HB, HE SOURCE SYSTEMS

• These retrofits are not too difficult or time
  consuming. The only machining on existing
  drivers is to make the exit groove in the reel
  plate 1 mm deeper.
• Looking into a third modification, easily
  retrofitted, to replace the adjustable washer
  stack on the reel axle with a crown nut
  arrangement. For ease in adjusting the snugness
  of the reel against the slide plate.
• All three retrofits can be done on the HE air
  drivers at CERN.
• Some older TSDs at CERN (and at Texas Tech,
  Mumbai) still need to be sent to Purdue for more
  extensive refurbishment.
• Retrofit and old TSD refurbishment costs look
  like MO budget items.

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HB, HE SOURCE SYSTEMS

• Wire getting stuck during retraction, at H2
  (Pawels report yesterday) is not fully
  understood. High enough friction to require
  hand-operation of the reel.
• May be fixed by above improvements, IF due to
  reel friction and/or non-straightness of source
  wire. But MUST avoid any really bad source
  tubes, of which a number are known at H2.
• New lower-support wire will isolate the spring
  fingers from the source wire. This eliminates
  wear on fingers and snagging source wire (one of
  the H2 episodes).
• Should use a good dummy wire to find all tube
  lengths and weed out bad calorimeter source
  tubes, before using radioactive wires in SX5.

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HB, HE SOURCE SYSTEMS

• Good news I established in November that
  35-foot source wires are sufficient for HB PSDs,
  as well as for all other locations in HCAL.
• Propose to make temporary brackets to mount HB
  PSDs at SX5 mezzanine
• Early mechanical tests of air driver and tube
  manifolds in situ.