Alpha particle emission is typically associated with heavy nuclei. What is a key shielding characteristic of alpha particles?

• A. They are easily stopped by a sheet of paper or outer skin
• B. They require thick lead shielding
• C. They travel long distances in air
• D. They have no mass

Answer: (A)

Alpha particles are heavy, highly charged bodies that interact strongly with matter, so they lose energy rapidly and have a very short range. This means they can be stopped by something as thin as a sheet of paper or the outer layer of skin, making external shielding surprisingly simple. Their strong ionizing power comes with limited penetration, so they don’t travel far in air and do not require thick shielding like gamma rays or neutrons do. They do have mass, so the statement that they have no mass isn’t accurate.