Rutherford Scattering
Fire a beam of alpha particles at a single heavy nucleus — adjust the alpha energy, target atomic number, particle count, and impact-parameter spread to watch Coulomb repulsion alone deflect each trajectory, most only slightly and a rare few sharply back the way they came.
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What you can adjust
- Alpha particle energy
- 1 – 10 MeV
- Target atomic number (Z)
- 13 – 92
- Number of alpha particles
- 5 – 40
- Impact-parameter spread (max |b|)
- 10 – 500 fm
The kinetic energy each alpha particle is fired at the foil with. Higher energy means a smaller distance of closest approach and smaller deflection angles overall.
How many protons the target nucleus has (79 = gold, the historical experiment's foil). A bigger Z means a stronger Coulomb repulsion and bigger deflection angles.
How many alpha particles fire at the nucleus, evenly spaced across the impact-parameter spread below.
The beam's alpha particles start with impact parameters evenly spaced from -b_max to +b_max (how far off-center each one is aimed). Smaller values aim more particles closer to a head-on hit.
About this simulation
What it shows
A row of alpha particles is fired at a single heavy nucleus, and each path is bent by electric repulsion. Most pass with a small bend, and a few close ones bounce almost straight back.
The key idea
The positive alpha particle and the positive nucleus repel each other with a force that grows as they get closer. The closer the aim and the higher the nuclear charge Z, the bigger the deflection, while a higher alpha energy lets it get closer in.
Try this
Lower Target atomic number (Z) from 79 (gold) to 13 (aluminium): the repulsion is weaker, so the alpha particles are deflected less.
Only the electric repulsion is modelled, and the nucleus is treated as fixed. Real alpha particles that come very close also feel the nuclear force, which is not included.