Nuclear structure and nuclear forces

Equipment

• 3D model of a nucleon cluster (protons/neutrons) in the nucleus
• Sliders for parameter and physical parameter adjusting size/binding
• Noise slider simulating random fluctuations
• Binding-energy-versus-A plot and quantity readout

Procedure

1. Inspect the nucleon cluster

   Run the simulation and rotate the view: nucleons pack into a nearly spherical blob of almost constant density — the "liquid drop" property. The cluster diameter grows slowly as $A^{1/3}$, reflecting $R \simeq r_0A^{1/3}$ with $r_0 \approx 1{,}2$ fm.

2. Read the binding-energy curve

   In the second figure, vary the physical parameter to shift the effective mass number: binding energy per nucleon rises quickly for light nuclei, peaks near iron, then declines — per the liquid-drop formula $E_B \approx a_VA - a_SA^{2/3} - a_C Z(Z-1)/A^{1/3} - a_A(A-2Z)^2/A + \delta$.

3. Add noise and reason about stability

   Increase the noise: the cluster shakes harder, yet the short-range nuclear force keeps the nucleus intact — only strong enough noise ejects a nucleon. Predict which nuclei (light or heavy) are easier to break using the binding curve, then test.

Simulation

Experiment history

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