Particle physics
Particle collisions and curved tracks
Relate track radius to momentum and magnetic field through r = p/(|q|B), and account for energy and momentum conservation in pair production.
Equipment
- Virtual cloud chamber with a uniform magnetic field
- Electron and positron beams with adjustable collision energy
- Track radius scale and momentum readout
Procedure
Set the detector field
In a real detector, verify the field polarity and map B before collecting events. Select a uniform central region and record its field strength; tracks outside it should not be used for a simple radius estimate.
Record a collision event
Select an electron–positron event and trace each outgoing charged particle through several detector points. Fit a circle to each projected track and record its curvature direction, radius, and uncertainty.
Compare curvature and collision energy
Repeat at a different beam energy and then a different B. Estimate transverse momentum from p = |q|Br (with unit conversion in real data), check how opposite charges bend in opposite directions, and discuss why a pair's tracks alone do not guarantee pair creation without accounting for conservation laws and the interaction context.