Gamma-ray

Key Stage 4

Meaning

Gamma-rays are a type of ionising radiation and the highest frequency and shortest wavelength of electromagnetic wave.

About Gamma-rays

Gamma-rays are transverse waves.

Gamma-rays can travel through a vacuum as well as through gases in the Earth's atmosphere.

The speed of gamma-rays through a vacuum is 300,000,000m/s.

As a wave gamma-rays can be:

• Transmitted - Gamma-rays can pass through a medium.
• Absorbed - The energy transferred by gamma-rays can be taken in by certain materials.
• Refracted - Gamma-rays can change direction when they cross the interface between two media.

However, unlike most waves gamma-rays cannot be:

• Reflected - There are no known materials on Earth that can reflect gamma-rays.

Unique Properties

Gamma-rays are the highest energy electromagnetic waves.

Gamma-rays are emitted from the atomic nucleus of unstable radioactive isotopes.

Gamma-rays cause electrons in materials to gain enough energy to leave atoms creating ions which can destroy chemical bonds.

Gamma-rays are the most penetrating, but least ionising form of Ionising Radiation.

Gamma-rays can penetrate most materials except for thick lead and thick sheets of other elements more dense than lead on the periodic table.

Gamma-rays cannot pass through heavy metals (metals with a high atomic mass).

Applications

Gamma-rays can be used to sterilise food and medical equipment because it causes electrons in materials to gain enough energy to leave atoms creating ions which can destroy chemical bonds in micro-organisms thereby destroying the micro-organism.

Gamma-rays can be used to irradiate cancerous tumors because they ionise atoms, destroying chemical bonds and can kill the cells. Cancer cells are weaker than healthy cells so more of the cancer cells will be killed than healthy ones.

Gamma-rays cab be used to trace the flow of fluids through organs because Gamma-rays are emitted from the atomic nucleus of unstable radioactive isotopes which can be injected into a patient and they can penetrate most materials so they leave the body without being reflected, refracted or absorbed.

Dangers

Gamma-rays can cause cancer because gamma-rays can penetrate soft tissue and can ionise and damage DNA molecules in the body cells leading to a mutation.

High intensity gamma-rays can cause radiation sickness because they can ionise and damage all parts of a biology killing that cell.