Physics – 5.2.2 The three types of nuclear emission | e-Consult

Alpha particles have a lower penetrating ability than gamma rays primarily due to their mass and charge.

• Mass and Charge: Alpha particles are significantly heavier and more positively charged than gamma rays. This means they interact more strongly with the atoms they encounter.
• Ionising Effect and Interaction: The high charge and mass of alpha particles lead to a strong electrostatic interaction with the electrons in the atoms of the material they pass through. This results in frequent collisions and the transfer of energy, causing ionisation. This rapid interaction means they lose energy quickly and are stopped over a short distance.
• Gamma Rays: Gamma rays are photons, which are uncharged and have no mass. They interact with matter through electromagnetic forces, but do not experience the same strong electrostatic interactions as alpha particles. They can pass through matter with minimal interaction, hence their high penetrating ability.

In summary, the strong electrostatic interactions of alpha particles cause them to lose energy rapidly, resulting in a low penetrating ability. Gamma rays, lacking charge and mass, can penetrate matter much more effectively.