Alpha Beta and Gamma Radiation

What is alpha radiation?

Alpha particles consist of two protons and two neutrons and have a travel range of up to a few centimetres in the air. The process of producing alpha particles is called alpha decay.

Although these particles can be absorbed by metal foils and tissue paper, they are highly ionising (i.e. they have sufficient energy to interact with electrons and detach them from atoms). Among the three types of radiation, alpha radiation is not only the least penetrating with the shortest range but is also the most ionising form of radiation.

Alpha decay

During alpha decay, the nucleon number (sum of the number of protons and neutrons, also called mass number) decreases by four, and the proton number decreases by two. This is the general form of an alpha decay equation, which also shows how alpha particles are represented in isotope notation:

\[^{A}_{Z}X \rightarrow ^{A-4}_{Z-2}Y+^{4}_{2} \alpha\]

Some applications of alpha radiation

Sources emitting alpha particles have a variety of uses nowadays due to the unique properties of alpha particles. Here are some examples of these applications:

What is beta radiation?

Beta particles are relatively ionising compared to gamma photons but not as ionising as alpha particles. Beta particles are also moderately penetrating and can pass through paper and very thin metal foils. However, beta particles cannot go through a few millimetres of aluminium.

Beta decay

In beta decay, either an electron or a positron can be produced. The emitted particle allows us to classify the radiation into two types: beta minus decay (β⁻) and beta plus decay (β⁺).

1. Beta minus decay

These are the equations for the disintegration of a neutron and beta minus decay:

\[n^0 \rightarrow p^++e^- + \bar{v}\]

\[^{A}_{Z}X \rightarrow ^{A}_{Z+1}Y+e^- +\bar{v}\]

n⁰ is a neutron, p⁺ is a proton, e^- is an electron, and \(\bar v\) is an antineutrino. This decay explains the change in the atomic and mass numbers of the element X, and the letter Y shows that we now have a different element because the atomic number has increased.

2. Beta plus decay

Here are equations for the disintegration of a proton and beta plus decay:

\[p^+ \rightarrow n^0 +e^+ +v\]

\[^{A}_{Z}X \rightarrow ^{A}_{Z-1}Y + e^+ +v\]

n⁰ is a neutron, p⁺ is a proton, e⁺ is a positron, and ν is a neutrino. This decay explains the change in the atomic and mass numbers of the element X, and the letter Y shows that we now have a different element because the atomic number has decreased.

Some applications of beta radiation

Like alpha particles, beta particles have a wide range of applications. Their moderate penetrating power and ionisation properties give beta particles a unique set of applications similar to gamma rays.

What is gamma radiation?

Because gamma radiation consists of photons that have no charge, gamma radiation is not very ionising. It also means that gamma radiation beams are not deflected by magnetic fields. Nevertheless, its penetration is much higher than the penetration of alpha and beta radiation. However, thick concrete or a few centimetres of lead can impede gamma rays.

Gamma radiation contains no massive particles, but, as we discussed for neutrinos, its emission is subject to certain conservation laws. These laws imply that even though no particles with mass are emitted, the composition of the atom is bound to change after emitting photons.

Some applications of gamma radiation

Since gamma radiation has the highest penetrating and lowest ionising power, it has unique applications.

Alpha, beta, and gamma radiation are types of nuclear radiation

Alpha, beta, and gamma radiation are types of nuclear radiation, but how was nuclear radiation discovered?

The discovery of nuclear radiation

Marie Curie studied radioactivity (nuclear radiation emission) shortly after another famous scientist named Henri Becquerel discovered spontaneous radioactivity. Curie discovered that uranium and thorium were radioactive through the use of an electrometer that revealed the air around radioactive samples had become charged and conductive.

Marie Curie also coined the term “radioactivity” after discovering polonium and radium. Her contributions in 1903 and 1911 would receive two Nobel prizes. Other influential researchers were Ernest Rutherford and Paul Villard. Rutherford was responsible for the naming and discovery of alpha and beta radiation, and Villard was the one to discover gamma radiation.

Rutherford’s investigation into alpha, beta, and gamma radiation types showed that alpha particles are helium nuclei due to their specific charge.

Instruments to measure and detect radiation

There are various ways to investigate, measure, and observe the properties of radiation. Some valuable devices for this are Geiger tubes and cloud chambers.

Differences between alpha, beta, and gamma radiation

Have you ever wondered what the difference between alpha, beta, and gamma radiation is? And where and how we use each type of radiation in everyday life? Let’s find out!

Effects of alpha, beta, and gamma radiation

Radiation can break chemical bonds, which can lead to the destruction of DNA. Radioactive sources and materials have provided a wide range of uses but can be very damaging if mishandled. However, there are less intense and less dangerous kinds of radiation to which we are exposed every day that do not cause any harm in the short term.

Natural sources of radiation

Radiation occurs every day, and there are many natural sources of radiation, such as sunlight and cosmic rays, which come from outside the Solar System and impact the Earth’s atmosphere penetrating some (or all) of its layers. We can also find other natural sources of radiation in rocks and the soil.

What are the effects of being exposed to radiation?

Particle radiation has the ability to damage cells by damaging DNA, breaking chemical bonds, and altering how the cells work. This impacts how cells replicate and their features when they replicate. It can also induce the growth of tumours. On the other hand, gamma radiation has higher energy and is made of photons, which can produce burns.