Cloud Chamber Simulator (2D)

Source Activity

Source activity 50

Particle Types

Magnetic Field

Field strength 0.0 T

Vapor supersaturated — tracks forming.

Live Readout

Tracks observed

Rate (per min)

How it works

A cloud chamber holds air saturated with alcohol vapor past its condensation point. A charged particle flying through it strips electrons from gas molecules along its path (ionization); those ions instantly seed tiny liquid droplets, so the particle's route becomes visible as a fog trail — exactly how Carl Anderson discovered the positron in 1932.

Track shape reveals the particle: alpha particles (helium nuclei) are heavy and doubly charged, so they ionize very densely over a short, thick, dead-straight path. Beta particles (electrons) are light and scatter off gas molecules repeatedly, leaving a thin, wispy, zigzagging trail. Cosmic-ray muons arrive from far above with enormous momentum and barely interact, so they draw a long, thin, perfectly straight line clean through the chamber.

Switching on the magnetic field bends every charged track into an arc via the Lorentz force (radius r = p/qB): the more momentum a particle carries, the straighter it stays. That is why muons barely curve, alphas curve a little, and the light, low-momentum betas spiral tightly — the same rule real physicists use to read a particle's charge sign and momentum straight off a chamber photograph.

Alpha — short, thick, straight Beta — thin, wispy, curls Cosmic muon — long, thin, straight