New Design of the Mask

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New Design of the Mask

• For L 3 m performance of the
• mask calorimeters is doubtful
• For larger L things look easier
• Question How much L do we
• need?

Achim Stahl
DESY Zeuthen
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TDR Design
Leackage makes precision Lumi hard
Too close to beamstrahlung
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Advantages

• Luminosity More likely to achieve 0.01
• No fakes can scatter from mask into ECal
• Vacuum much better, large orfice, bellow, valve
• Space for electronics available
• Better separation of outer Cal from beamstrahlung
  
• 
  (5cm -gt 8cm)
• Hermetic to 3.9 mrad (was 5.5 with gaps)
• Shintake monitor taken into account

L approx. 4 meters
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Open Questions

• Does the optics work
• Change in Radius of ECal 5 cm in
• Change in Radius of HCal 5 cm out in parts
• Many things not checked yet
• Backscatters from Cal front faces
• Leackage through the mask
• Vertex cables are longer
• .

L approx. 4 meters
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