Background Radiation
BACKGROUND RADIATION is a combination of NATURAL and MAN-MADE radiation that is around us all of the time.
NATURAL sources of background radiation include:
- Radon Gas
- Cosmic rays from space
- Rocks
- Food
MAN MADE sources of background radiation include:
- Fallout from nuclear weapons testing
- Nuclear accidents
- Radiotherapy
- X-ray (CT Scans)
Different people are exposed to different amounts of BACKGROUND RADIATION, and it depends on the where they LIVE and their OCCUPATION. eg. A person working in a nuclear power plant will be exposed to more radiation than an average person.
The amount of radiation received by a person is called the DOSE.
Radiation dose is measured in SIEVERTS (Sv).
1,000 milliSieverts (mSv) is equivalent to 1 Sievert (Sv).
Corrected Count Rate
When measuring the count rate (activity) of a radioactive sample using a GEIGER-MULLER TUBE, the BACKGROUND RADIATION needs to be taken into account. The steps to follow are:
1. Measure the BACKGROUND RADIATION by pointing the GEIGER-MULLER TUBE into the air.
2. Point the GEIGER-MULLER TUBE at the sample being measured; this will give the reading of the sample AND background radiation combined.
3. SUBTRACT the sample reading by the background radiation reading to give the CORRECTED COUNT RATE.
