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Engineering aspects of the Detector interface. Knut Skarpaas VIII. Detector interfaces. Collider hall Final magnet supports Assembly Sequence. Collider Hall Geometry. Detector Size Currently modeling structure for small US design Small detector has a strong following

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Engineering aspects of the Detector interface

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detector interfaces
Detector interfaces
  • Collider hall
  • Final magnet supports
  • Assembly Sequence
collider hall geometry
Collider Hall Geometry
  • Detector Size
    • Currently modeling structure for small US design
      • Small detector has a strong following
        • Magnet support for last quads fairly rigid
        • Compact package reduces deflections
        • Detector group is further along on this design
          • We are in continuous contact with many of the detector working groups
collider hall detector assembly procedure
Collider Hall /Detector Assembly Procedure
  • Assembly staged during beamline commissioning
      • Must shield detector assembly area from the beam
      • Movable barrier
      • Temporary support for beamline
        • Must act like detector
  • Final focus assembly dependent on magnet support method
      • Cantilever
      • Support tube
  • Access to Detector Sub-components
    • Vertex detector
    • Central tracker
      • Endcaps may be captive
        • Segment endcaps
magnet support options
Magnet support options
  • Design goals for various support options
    • Minimize deflections
      • Minimize unsupported span
      • Put support near critical deflection points
      • Put support near massive items
        • Current cantilever option has support near mask centroid
  • Maximize moment of inertia (minimize sag)
    • Tubular support advantageous
      • Will need access ports to work on / install magnets
  • Minimize mass supported by tube
  • Some mask forces may be transferred to the doors
design goals for various support options cont
Design goals for various support options cont.
  • Material requirements
    • Minimize radiation length of material near Interaction Point
      • Cantilever design has no material at IP
    • Radiation hard design
      • Adhesives / polymers may degrade
  • Interface with required detector components
    • Vertex detector in bore (if support tube)
      • If cantilever, support vertex detector from mask tips or from central tracker
    • Masks (held by cantilever or inside support tube)
    • Tungsten masks are massive
      • 2500 lb requires support for door opening
    • Central tracker hugs outer bore (or masks)
    • Pass through steel in door
design goals for various support options cont1
Design goals for various support options cont.
  • Door opening to be minimized to reduce Br near quads
  • Clearances
    • Assembly clearances
    • Allow for gravitational deflections
    • Current cantilever deflects .16” with door open
    • Seismic clearance
      • Site specific
  • Services
    • Vertex cables in bore (if support tube)
    • Cooling for vertex detector
        • Vertex detector requires 170k nitrogen gas
        • Foam or vacuum insulated lines
          • Foam lines are large (2”)
    • Luminosity monitor cables / cooling
      • In bore for most options
assembly sequence
Assembly sequence
  • Must be able to put detector together first time
  • Must be able to access various components for servicing
  • Minimize time to get to buried components
    • Vertex servicing
    • Central tracker servicing
allow for magnet positioning
Allow for magnet positioning
  • Coarse adjust
    • First time alignment
    • Remote alignment to remain within fine adjustment range
  • Magnet Coarse Adjustment options
    • Actuation
      • Screw
      • Ramp
      • Cam
      • Bellows or piston with liquid or gas
      • Piezo
    • Drive style
      • Motor (stepper or servo)
      • Can not be used in high magnetic field
      • Drive shafts can transmit torque into bore
        • Wind up problems can be eliminated with proper gear boxes
        • May contribute too much heat / vibration
      • Motor (hydraulic / pneumatic) (rotary or linear)
        • Seals may be a problem in high radiation areas
        • Gas may be too compressible
        • Hydraulic fluid may not be radiation hard
        • Vibration and heat can be low
      • Peizo
        • Stroke may not be sufficient for the coarse adjust
fine adjust
Fine adjust
  • Get to final magnet location
  • Active positioning
    • Needs to be radiation hard
    • Non-magnetic
  • Fine Adjustment Options
    • Due to the fast response, and non-magnetic properties of piezo electric actuators, this is our current choice
interferometer compliant
Interferometer compliant
  • Several configurations possible
    • Maximize stability / minimize detector penetrations
  • Holes / windows in support allow sight to magnets
  • Vacuum / gas transport lines
    • Vacuum requires a joint to the stabilized object
    • Transport lines can transmit vibration
    • If vacuum is used with windows, windows may shift beam
    • Gas is nice, but index of refraction changes with temperature
      • Heat from electronics may shift beam
support tube
Support tube:
  • Tube passes through detector
    • Support styles possible:
      • Simple – Simple
        • Deflection is maximum & stress is high in center
          • The center is a bad place for high stress since it has a smaller moment of inertia and requires minimal material
      • Fixed – Rolling
        • Deflection is smaller & stress is high on ends
      • Fixed-Intermediate Support- Intermediate Support-Rolling
        • Tricky stress allocation
    • Central tracker group does not like this option
      • They would like to put detectors near the inner masks
  • Tube is installed from each tunnel
  • May be mounted to a pier extending into pit
    • While running, support is near mask CG
    • Simple – Simple
      • Deflection is maximum when door is open
        • Deflection good while running
    • Fixed – Simple
      • Deflection is smaller but stress is high on one end
detector final focus options
Detector / final focus options:
  • Option 1
    • SLD style detector
      • Pro: Quick access /easy detector shapes
      • Con: Large pit / unstable magnets
  • Option 2
    • SLD like detector with reduced door opening
      • Concrete pillar under magnets (except last 2)
      • Last 2 magnets on short cantilever or held by door
      • Door supports trimmed on outside (doors may need counter weight)
        • Pro: Quick access /easy detector shapes
          • All but last two magnets are on “bedrock”
        • Con: Last magnets rely on detector for stability (but could be actively isolated)
detector final focus options cont
Detector / final focus options cont.:
  • Option 3
  • BaBar like detector split door
    • Concrete pillar under magnets (except last 1)
    • Cantilever last magnet and mask
    • Door supports trimmed on outside (doors may need counter weight toward IP)
      • Pro: Quick access
      • Con: ECAL and HCAL must be split to remove (may require difficult rigging)
  • Option 4
    • SLD like detector (cut off outer feet)
      • Key shaped pit
      • Roll detector to open
      • Fixture to open (to hold cantilever)
        • Pro: Stable / all but last magnet on bedrock
        • Con: Complicated pit / many cables to deal with / vac. dis-connect
        • Long down time to get to vertex detector
detector final focus options cont1
Detector / final focus options cont.:
  • Option 5
    • Central detector spool package with Small detector layout
      • Top splits in middle (iron and HCAL move to sides)
      • Spool cranes out
      • Shake spool
        • Pro: Stable
        • Con: Complicated pit / hard to get inside spool / vac. dis-connect / tricky wiring
assembly procedures small detector cantilevered supports
Assembly Procedures(Small detector / cantileveredsupports)
  • Assemble detector on shielded side of pit
    • Beam line commissioning happens using the real doublets on the other side of the pit with a temporary support
    • Remove EM magnets on pier and pull doublet back into tunnel
    • Rotate the detector to become parallel to the beam line
    • Roll the detector into place (including doors)
    • Slide cantilevered support tubes through doors
    • Make up vacuum and transfer load of masks from detector to the support tube
vibration issues
Vibration Issues
  • Since the extent of vibration amplification varies widely with various geometries, emphasis until this point has been put on solidifying the detector geometry
    • Detector revisions occur biannually
  • As detector shapes and magnet styles become more stable, vibration isolation methods will be explored further
    • Several possible vibration isolation scenarios are being considered
    • Under all conditions, local noise must be isolated from the detector
      • Local traffic minimized
      • Pumps on isolators on separate slabs
      • Well thought out plumbing and other services
vibration issues continued
Vibration Issues Continued
  • Find a stable site and make all components rigid
    • Many problems could arise if we do not have a “Plan B” (and the site becomes noisy)
  • Have a rigid detector and a floating (active / passive / both) magnet support
    • A permutation of this option may be the most practical for a large detector
  • Float the entire detector (or a large portion of it) on a gas suspension system
    • A possible air system has been considered which incorporates a variable natural frequency which allows adjustment for detector mass changes
  • Communication has begun with the LIGO group
    • Work is currently being done at LIGO to stabilize a several hundred kilogram mass to 1 nm
    • The LIGO system currently stabilizes a mass to a level several orders of magnitude better than NLC requirements. However, the system used is not currently practical for a physics detector. (Their frequency requirements are also different)
thermal issues
Thermal Issues
  • A high degree of positional stability requires a thermally stable environment
    • Detector will most likely be under a thick (~6’ thick) concrete lid for radiation protection reasons
      • Large thermal masses should aid thermal stability
  • Thermal excursions happen slowly and require a coarse adjustment range for the movers
  • Tunnels which connect to pit are fairly cool at this point
    • Should not be a large heat source (and may be sealed from pit)
    • Tunnel temperature is set by local cooling tower capacities
      • Have looked at wet bulb maximums at several sites
  • Detector design is still undergoing changes
  • We are in contact with key people in many detector working groups
  • One of the more popular detector choices is being structurally modeled currently
  • Several issues will be studied and prototyped in the near future
    • Vibration isolation options will be pursued