Befing Tracking R&D Review Richard Partridge1 Augmenting TrackerHit with Strip Info u Existing TrackerHit class works OK for 3D hits, but needs to be augmented for the 2D info from strips u First resolve what is meant by hit position and error matrix Somebody should check that I got the math right! u Look at what info is needed for track finding and fitting Should make this info easily accessible from the tracker hit Propose a SiStrip class that provides this additional info Alternatively, could do much the same thing with a SiStripCluster class Probably other alternative as well…

Befing Tracking R&D Review Richard Partridge2 Proposed Hit Position Convention u Let local sensor coordinates be given by u, v, and w u is the measurement coordinate v is the coordinate along the strip direction w is the coordinate normal to the sensor surface u Assign the local hit position as follows u is the hit position v is the center of the strip w is the middle of the sensitive region u In the global coordinate system, assign unit vectors parallel to the local coordinates u Hit position in global coordinates is found by coord. transform

Befing Tracking R&D Review Richard Partridge3 Proposed Error Matrix Convention u Measurement coordinates are not necessarily cartesian u Thus, measured and unmeasured coordinates are mixed together in the cartesian error matrix u Putting a 0 in an unmeasured coordinate could cause problems with algorithms that try to invert the error matrix u Putting a big number in an unmeasured coordinate could introduce round-off problems u Propose that error matrix be defined in local coordinates as follows

Befing Tracking R&D Review Richard Partridge4 Proposed SiStrip Class Fields u Methods: get/set for all fields and addhit FieldTypeDescription StripIDintIdentifier that uniquely specifies the strip StripChargedoubleCharge deposited on strip, including noise StripCenterSpacePointPosition of the center of the strip StripLengthdoubleLength of the strip StripDirectionSpaceVectorUnit vector parallel to the strip MeasurementDirectionSpaceVectorUnit vector parallel to the measurement dir. SensorSiSensor??Sensor that this strip lies on RawTrackerHitBaseRawTrackerHitRaw tracker hit for this strip SimTrackerHitsList List of hits that deposited charge in this strip TimeDoubleTime of hit