What can stop beta particles?

A few millimeters of aluminum is effective in stopping beta particles because beta particles are charged particles (electrons or positrons) emitted during radioactive decay. These particles have relatively low mass and energy compared to alpha particles and gamma rays, which allows them to be easily absorbed or scattered by materials like aluminum.

Aluminum is commonly used as a shielding material in various applications, particularly where beta radiation is a concern. The thickness of a few millimeters is typically sufficient to stop beta particles, as they lose their energy primarily through interactions with matter, leading to ionization and scattering. Materials that are dense or heavy, such as lead, are not necessary for beta particle shielding because those particles can be effectively absorbed by lighter materials.

While wood and concrete can also attenuate beta particles, their effectiveness may depend on the density and thickness. However, these materials may require more thickness than that of aluminum to achieve the same level of radiation shielding, making aluminum the most practical and efficient choice among the options.