BTeV Pixel Modeling, Prototyping and Testing

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BTeV Pixel Modeling, Prototyping and Testing

• C. Newsom
• University of Iowa

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Overview

• Vacuum Vessel Models
• Internal support structures
• Vacuum Interconnect Board
• HDI/Flex Cable tests
• MultiChip Module prototypes
• Materials testing

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Vacuum Vessel Models

• Cylindrical Model
• Rectangular Model

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Cylindrical Model
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Cylindrical Model

• Shown here are cables from both front and back
  sides of the pixel module.
• Side cables must twist, stressing the pixel
  module non-symmetrically.
• Insufficient space for side cables

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Rectangular Model

• Rectangular model has more space for side cables
• Cannot plug cables into the sides since there is
  a magnet pole behind it.
• Cooling manifold interferes with horizontal
  cables from the back of the module.

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Internal Support Structures

• Integrated carbon support/manifold
• Carbon Half Barrel Structure

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Integrated Carbon Support/Manifold

• The MultiChip Modules mount directly on the
  carbon manifold
• Pure carbon joints are not robust and need more
  research
• Manifold to Chip Module connections unsolved.

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Carbon Half Barrel Design

• Barrel is double walled laminated carbon.
• Cables are moved to a side board.
• Space at bottom now available for motion, pump
  structures
• Insufficient space for HDI/daughter boards shown
  here.
• Major assembly problems

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Vacuum Interconnect Board

• Carry 35,000 signals from inside to outside the
  vacuum
• Constructed from 6 separate boards each with its
  own o-ring.
• Daughter cards have been removed to gain space.
• Ribbon cables pass through the surface and plug
  into the back side.
• Should we join the 6 boards, build a single
  board, ?

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Vacuum Interface Board
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HDI/Ribbon Cable Flexor

• One end is at -10C, and one at 25C to cool the
  power lines.
• Must absorb 2cm motion of half barrel during
  tuning.
• The cable must work in a vacuum.

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MultiChip Module Prototypes

• Beryllium prototypes
• Aluminum Modules (serpentine flow)
• Aluminum Modules (parallel flow)
• Stainless Steel Module (parallel flow)
• Fuzzy carbon prototypes
• Initial Design
• Improved Carbon Joints
• Current Design

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Beryllium Prototype Modules
Serpentine flow 2mm channel (aluminum)
Parallel flow 2mm channel (aluminum)
Parallel flow 0.5mm channel (stainless steel)
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Prototype Flow Test Results
Parallel Channel Al Module
Parallel Channel SS Module
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Thermal Test Setup

• Measure temperatures using RTD sensors
• Heat both surfaces with brass heat spreaders on
  silicon wafers.
• Variable flow and heat input

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Aluminum Module Heat Tests

• Heating curves at nominal 0.5W/cm2, both sides
• One liter/min flow

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Temperature Results
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Vibration Tests

• Vibrations perpendicular to the surface.
• Vibration vs flow from 0 to 1.5L/min
• Corrected for external vibrations
• All motions are below 1 micron

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MCM Vacuum Test Vessel
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Fuzzy Carbon Prototypes

• Thermal Prototype
• Mechanical Prototype
• Current Status

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First Fuzzy Carbon Prototype

• Temperature drop of 7 degrees (ok)
• Mechanically very weak
• Manifold joint failures

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Mechanical Prototype

• This module looks very similar to the first
  prototype
• It differs in that the fibers are more randomized
  so that cross connects can strengthen the coupon
• Additional reinforcement at ends was added
• The module was considerably stronger but
  additional effort is needed
• Coupon still has joint problems

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Carbon Carbon Joint Efforts

• Note effects due to 20 shrinkage
• Nanotubes added to increase joint strength
• Still much weaker than conventional epoxy

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Ovalized Joined Tubing
Original Design
Ovalized Design
Ovalized Glassy Carbon Tubes
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Future Fuzzy Ovalized Carbon Modules

• Ovalized tubing provides thinner cross section
• Fibers connect more directly to the coolant tubes
  giving much better heat transfer
• Connected carbon tubes are considerably stronger
• The manifold joints clearly need more RD

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Materials Testing

• Stress and strain effects
• Vacuum effects
• Neutron activation
• Radiation Damage

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Youngs Modulus Apparatus
Sound is a pulse with most components in the 1MHz
range.
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Epoxy Study

• Can measure speed of sound to 0.5
• From speed of sound, we can know Youngs modulus
• Will measure before/after effects of radiation,
  stresses, etc.

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Neutron Activation

• Will modify an 80gram Pu/Be neutron source for
  activation studies
• Source is available indefinately
• Must test all materials and the products used to
  clean them!