ITTF Detector Model Ben Norman Kent State University
ITTF Detector Model Ben Norman Kent State University For the Integrated Tracker Task Force 1
Outline Introduction Detector Representation n Material Shape Placement Usage n n Detector Container Detector Builder Extension n n Subsystem responsibilities ITTF responsibilities Material Interaction n n Intersection Scattering & Energy Loss Summary 23 Sept 2002 ITTF Review (BNL) 2
Detector Representation Detector Volume n n Active Detector Hit Information Passive Detector Simple Scatterer Flags n n On: added to detector container Active: provides hit information Discreet: discreet scatterer (SVT ladder) Continuous: continuous scatterer (TPC padrow) 23 Sept 2002 ITTF Review (BNL) 3
Detector Representation II Material n n Density Radiation length Shape (Cylindrical, Rectangular, Conical) n n Extent Boundaries (including edge regions) Placement n n Normal representation Center representation 23 Sept 2002 ITTF Review (BNL) 4
Detector Representation III 23 Sept 2002 ITTF Review (BNL) 5
Usage Sti(Coded)Detector. Builder n n Reads offline d. B Creates all materials, shapes, placements, & detectors Sti. Detector. Container n n Stores Detectors in tree structure Ordered by: (extensible) w Forward/mid/backward rapidity w Radial position / z w Azimuth 23 Sept 2002 ITTF Review (BNL) 6
(Sti. Detector. Container) Root [Thanks, Mike] Forward Mid Layer 1 Section 1 Backward Layer n Section n Element 1 23 Sept 2002 ITTF Review (BNL) Element n 7
Extension Subsystem tasks: n n Write St. XXXHits objects into St. Event Transformation functor St. XXXCoordinate. Transform w St. XXXLocal. Coordinate St. Global. Coordinate n Sql. DB access to detector physical characteristics: w Size w Position w Material – density & radiation length approximations 23 Sept 2002 ITTF Review (BNL) 8
Extension II ITTF Responsibilities: n Create Sti. Kalman. Track. Node subclass w Use z as independent parameter (instead of r) n Add to Sti. Hit. Filler w fill. XXXHits(): copies St. Hits to Sti. Hits for tracking n Add to Sti. Geometry. Transform: w Pointers to transform functors w Utility methods n Add to Sti. Coded. Detector. Builder: w w n Materials in build. Materials() Shapes in build. Shapes() Placements in build. Detectors() Detectors in build. Detectors() Add to Sti. Local. Track. Seed. Finder w Starting points for seed-finding (eg. , outer layers of FTPC) 23 Sept 2002 ITTF Review (BNL) 9
Material Interaction Intersection - Sti. Material. Interaction n n Line extrapolation for short steps Helix extrapolation available for long steps Scattering / Energy Loss n Sti. Material. Interaction determines w # of radiation lengths traversed in each step w Radial distance traversed w Mean density n Track finder computes E-loss & effect of scattering on error matrix 23 Sept 2002 ITTF Review (BNL) 10
Conclusions Modularity assures extensibility Well defined path for extension Tracker truly integrates heterogeneous STAR components 23 Sept 2002 ITTF Review (BNL) 11
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