SiD Opportunities in Tracking and Vertexing

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SiD Opportunities in Tracking and Vertexing

• Steve Worm
• Rutherford Appleton Laboratory

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Outline

• The ILC tracking requirements
• SiD Tracking Concept
• Central tracker
• Vertexing
• Opportunities for the UK

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Vertexing challenges at the ILC

• Understanding the new physics requires heavy
  quark ID
• Higgs Branching ratios are they as expected in
  the Standard Model?
• Separation of b from b, and c from c will be
  important.
• High efficiency, purity to measure multi-b
  states, eg. ee- ? HHZ, ttH
• Leads to reduced combinatorial background.
• ? Excellent b, c (and tau) tagging crucial

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ILC Tracking Requirements

• Unprecedented momentum resolution
• Example
• Other requirements
• High precision, low mass
• Excellent tracking in far forward
• Robust against backgrounds, pileup
• Must be much better than existing detectors

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How to get b/c ID, excellent tracking?

• The tracking challenges of b/c finding met by
  silicon
• Is there room for improvement?
• What is the next challenge?
• Bigger?
• Industrialization of silicon modules
• made CMS, ATLAS possible
• More standardisation and simplification
• needed for any next step
• Better!
• New technologies(?)
• Better/thinner detector means charge
  identification possible
• Excellent precision in rf and z can reconstruct
  neutrinos in semileptonics
• Better detectors needed
• Lower mass, better precision ? better
  understanding of the physics

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Mechanical Challenges

• Requirements extremely high precision, low mass
• Practical aspects for vertex detector
• Low power sensors gas cooled
• Low mass ladder ends, cables, services
• Mechanical stability to few microns
• Must withstand thermal cycling
• Must be able to hold, align, bond, etc
• The goal of 0.1 per layer is very ambitious!

100
CMS
(early TESLA estimate)
ATLAS
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ILC Requirements

• ILC physics requirements vs. best detectors to
  date
• Building the ILC detectors a real challenge
• Tracking presents some of the biggest challenges

--Mark Oreglia, Feb 2007
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SiD Tracking Features

• Central Tracker
• 5 layers of strips
• 25 µm pitch, 50 µm readout
• Vertex Detector
• 5 layers of pixels
• 20 µm2 pixels
• Forward Region
• 4 layers of pixel disks
• 5 layers strip disks
• No bulkheads, ladder blocks
• General features/plans
• Designed for accessibility
• Carbon fiber shell structure
• Baselined, but still changeable

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SiD tracker overall layout

• Designed for accessibility

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SiD tracker

• Barrel Features
• Russian Doll layout for physics and practical
  considerations
• 5 layers of 25 µm strips (overkill? more layers
  needed?)
• Modules 10x10 cm2 tiles, 0.8 X0/layer
• Disk Features
• 5 layers (x2) with R, f strips
• Modules not well fleshed out 1.3 X0/layer
  target

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Vertex detector layout

• Basic design includes
• 5 layer pixels, short barrel (followed by gap)
• 4 pixel disks each side, also strip disks
• 0.1 X0/layer, Rin 14 mm
• Carbon fibre shell for silicon layers, disks
• Plan for cable routing, cooling
• Ideas for beam pipe support

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Mechanical design

• Design guides
• Minimize mass in the forward
• Tracking to as far forward as possible
• Carbon fibre shells for vertex detector
• Accessible vertex detector, tracker

Vertex Detector Coverage
X/X0 vs Theta
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20
10
0
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Tracking performance

• Performance with ttbar background
• s1/2 500 GeV
• Vertex detector seeded patrec working (3 hits)
• Good efficiency (gt98)
• Good resolution (few x 10-5)

Efficiency
Central Resolution
Black VXD basedRed VXD tracker
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Tracking Philosophy

• The SiD approach to tracking
• Inside-out tracking emphasized
• Vertex detector seeded patrec
• Also outside-in, Calorimeter-assisted
• tracking algorithms
• Greater emphasis placed on vertex
• detector, fine-pitched EM cal

• Pattern Recognition
• Not as visual as TPC but precision, resolution
  better
• Vertex detector seeded patrec now demonstrated

Silicon Tracking
TPC Tracker
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UK Opportunities

• What can we do? First look at what we have we
  done!
• Built barrels of strips for ATLAS
• Built disks for ATLAS, LHCb
• Built vertex detector for SLD
• Delivered silicon strip readout chip for CMS
• Provided engineers and support for major HEP
  projects etc
• World-class developments of vertex sensors,
  mechanics, and benchmarking
• What is needed by SiD?
• Vertex sensors mechanics
• Engineering detail for vertexing tracking DAQ,
  layout
• Software realistic tracking, vertexing,
  algorithms, 5 layers?, etc
• Forward anything!

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