Alpha radiation & beta radiation simply explained: You need to know that
When it comes to radioactivity, the terms alpha radiation and beta radiation often appear. You can find out exactly what this is in this practical tip.
Alpha radiation - what is it?
Alpha radiation is a relatively harmless radiation that occurs when alpha decays.
- In alpha decay, two protons and two neutrons are rejected by the nucleus. The mass number of the atomic nucleus thus decreases by 4 units and the atomic number by 2 units.
- In other words, one could say that the alpha particle is a double ionized helium atom, since the helium nucleus also has 2 protons and 2 neutrons.
- Due to the relatively large mass (4 u) of an alpha particle, the penetration depth is very small.
Beta radiation - what is it?
In addition to the alpha radiation, there is also beta radiation.
- Mostly the β‾ decay is considered. Here, a neutron changes into a proton. However, this sends out an electron and an antineutrino. This decay mostly occurs with nuclides with an excess of neutrons. The mass number remains unchanged, but the atomic number is increased by 1.
- There is also beta plus decay, in which a proton converts to a neutron. However, this emits a positron, which like an electron, is just made up of antimatter, and an electron neutrino, which is a neutral particle that is difficult to detect.
- In contrast to the alpha radiation, the beta radiation penetrates somewhat deeper. When the beta particles penetrate, energy is transferred to the material and ionization takes place in a layer near the surface which corresponds to the depth of penetration of the particles.
How does uranium break down into lead?
For a better understanding, we will explain the decay of uranium to lead as an example.
- A uranium atom (238/92) is said to decay into a lead atom (206/82). First subtract the mass numbers: 238 - 206 = 32 u. Now you know that 32 nucleons (i.e. protons and / or neutrons) are released during decay. This corresponds to the mass number of 8 alpha particles.
- Then subtract the atomic number: 92 (p +) - 82 (p +) = 10 (p +). However, 8 alpha particles have a charge of 8 ⋅ 2 (p +) = 16 (p +). Since the atomic number only changes by 10 positive charges, 6 beta decays still have to take place. This in turn increases the atomic number by 6 positive charges and the mass number remains the same.
In the next practical tip, we will explain how quantum computers work.