ASNT Industrial Radiography Radiation Safety Practice Test

How does the mass of beta particles compare to alpha particles?

1. Much greater than that of an alpha particle

2. Similar to that of an alpha particle

3. Much less than that of an alpha particle

4. Equal

The correct answer is: Much less than that of an alpha particle

Beta particles are charged particles that are emitted during the radioactive decay of certain types of atomic nuclei. They are much less massive than alpha particles. An alpha particle consists of two protons and two neutrons, which makes it significantly heavier due to the greater number of nucleons (the particles in the nucleus) it contains. In contrast, beta particles can be either electrons or positrons, which are fundamental particles that have a mass roughly 1/1836 that of a proton or neutron. This stark difference in mass is why beta particles are considered to have much less mass compared to alpha particles. Understanding the mass difference is important in radiography and radiation safety because it impacts the penetration ability and biological effects of these particles when interacting with materials and biological tissues. Beta particles, being lighter and having a different charge, interact with materials and the human body in unique ways compared to the heavier, positively charged alpha particles. This fundamental distinction is crucial for safety protocols in radiography practices and for ensuring proper protective measures are in place.