1. Thoughts on B-Field Uniformity for the SD Tracker SID Tracking Meeting October 22, 2004 Bruce Schumm UC Santa Cruz March 2001 Baseline Thanks to Harry Weerts!

2. Gaseous Tracking: spec is (I believe) B r /B z < 10 -3 What is corresponding spec for Si tracking? Sources of concern: Pattern recognition and curvature reconstruction (will not address) Pulse development (will address)

3. Pulse Development Simulation Long Shaping-Time Limit: strip sees signal if and only if hole is col- lected onto strip (no electrostatic coupling to neighboring strips) Incorporates: Landau statistics (SSSimSide; Gerry Lynch LBNL), detector geometry and orientation, diffusion and space-charge, Lorentz angle, electronic response

4. Faking the Magnetic Field Different B-Fields (B-field) or detector tilt to simulate Lorentz angle (Tilted) Resolution Magnetic Field (T) Michael Young, UCSC Resolution slightly better for lower Bfield

5. Efficiency versus Track Angle  Need to tilt detectors to regain efficiency? (but this is for  =10,  =90 – worst case) Michael Young, UCSC Efficiency won’t fall off as fast with track angle

6. What do the experts (ATLAS, CMS) say? (Thanks to Alex Grillo, ATLAS) ATLAS has a 2T solenoidal field In the farthest reaches of their Si tracking, B r /B z  5%, so B r  0.1T. If this spec is driven by relative considerations, then this is a 5% requirement. If spec driven by absolute considerations (B r < 0.1T), then this is a 2% requirement. WHAT ABOUT CMS?