The three types of nuclear emission

In this section, we explore the different types of radiation emitted by unstable nuclei, focusing on the nature of these emissions, their effects, and how they interact with electric and magnetic fields.

Emission of radiation from the nucleus

Radioactive decay is the process in which an unstable atomic nucleus emits radiation to become more stable. This process is:

• Spontaneous: It happens naturally without any external influence.

• Random in Direction: The emitted radiation can travel in any direction.

The emitted radiation comes in three main forms: alpha (α), beta (β), and gamma (γ) radiation.

Alpha, beta and gamma radiation

Alpha radiation

Nature of Radiation:

• Composed of 2 protons and 2 neutrons.

• Essentially the same as a helium nucleus.

• It has a relatively large mass and positive charge.

Ionising Effects:

• Highly ionising due to its large mass and double positive charge.

• It can easily knock electrons out of atoms as it passes through materials.

Penetrating Abilities:

• Low penetration. It can be stopped by a sheet of paper or a few centimeters of air.

• It is dangerous if inhaled or ingested but cannot penetrate human skin.

Deflection in Electric and Magnetic Fields

• Deflected in electric and magnetic fields due to their positive charge.

• The direction of deflection depends on the polarity of the field.

• They are deflected less than beta particles due to their greater mass.

Ionising Effects and Their Causes

• Alpha particles have lower speed compared to beta particles but possess high mass, giving them significant energy to ionise atoms effectively.

• The positive charge of alpha particles makes them interact strongly with electrons in atoms, leading to high ionisation.

Beta radiation

There are three main types of nuclear radiation, each with distinct characteristics:

Nature of Radiation:

• Beta-minus (β⁻) particles are electrons emitted from the nucleus when a neutron decays into a proton.

• Lightweight and negatively charged.

Ionising Effects:

• Moderately ionising.

• Its smaller size and lower charge make it less effective than alpha radiation at ionising atoms.

Penetrating Abilities:

• Moderate penetration. It can be stopped by a few millimeters of aluminium or other light metals.

• It can penetrate the skin but is blocked by denser materials.

Deflection in Electric and Magnetic Fields

• Also deflected in electric and magnetic fields, but in the opposite direction to alpha particles because they are negatively charged.

• Being lighter, they are deflected more than alpha particles.

Ionising Effects and Their Causes

• Beta particles move at higher speeds but have lower mass, giving them moderate ionising ability.

• Beta particles, being negatively charged, also interact with atomic electrons but to a lesser extent due to their smaller mass and single charge.

Gamma radiation

Nature of Radiation:

• Electromagnetic wave with no mass and no charge.

• High-energy photons, similar to X-rays but even more energetic.

Ionising Effects:

• Weakly ionising.

• As a form of electromagnetic radiation, it is less likely to interact with atoms compared to charged particles like alpha and beta radiation.

Penetrating Abilities:

• High penetration. It can pass through several centimeters of lead or meters of concrete.

• It requires dense materials to effectively shield it.

Deflection in Electric and Magnetic Fields

• Not deflected in electric or magnetic fields since they have no charge.

Ionising Effects and Their Causes

• Gamma radiation consists of photons that travel at the speed of light, but because they have no mass, their ability to ionise is lower.

• Gamma radiation has no charge, meaning it has a lower probability of interacting with atoms and ionising them.

The penetration power of alpha, beta and gamma radiation

Change in the nucleus