Radioactivity

Radioactive Decay

Random radiation given out by the nucleus.

Activity Rate

Measured in Becquerels (Bq)

The rate of which a source if unstable nuclei decay

Count Rate

Number of decays recorded each second by a detector- eg the Geiger- Muller counter.

Half Life

The time it takes for half the unstable nuclei to decay.

Alpha Particles

Helium nucleus

Stopped by paper or a few cm’s of air

Highly ionising

Beta Particles

A high speed electron.

Stopped by a few mm of Aluminium or 1m of air

Slightly ionising

Gamma Rays

High energy electromagnetic wave.

Is continuous in air but stopped by concrete or thick lead wall

High penetrating power but weakly ionising

Radioactive Contamination

The presence of unwanted radioactive atoms on other materials

Irradiation

The exposure of materials to radioactive

Natural sources of background radiation

Radioactive rocks (granite) and cosmic rays

Man made sources of background radiation

Nuclear weapons fallout and nuclear accidents.

What affects dosage of background radiation?

Location and occupation

Nuclear Fusion

Two light nuclei joined together to form a heavier nucleus. The mass of the nuclei can be converted into energy

Nuclear Fisson

One large unstable nucleus absorbs a nucleus and splits into two smaller daughter nuclei while releasing neutrons and energy.