Reading Particle Tracks

Momentum from curvature

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• A charged track curves with $p = 0.3\,B\,r$ (GeV/$c$, tesla, metres).
• The direction of curl gives the sign of the charge.
• Fast particles bend little; strong fields and big trackers measure them.

Steps

1. Bent by a magnet
2. A gentle curve
3. Inside the detector
4. Opposite curls
5. How bent is a fast track?
6. Why such strong magnets?