Date post: | 01-Jan-2016 |
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Lesson Objectives
• Identify sources of background radiation.
• Understand the use of alpha sources in smoke detectors.
• Understand how radioisotopes are used as industrial tracers
Success CriteriaGrade E Grade C Grade A
Recall the main sources of background radiation
Recall background radiation can come from man-made sources and waste products
Evaluate the relative significance of sources of background radiation
Recall industrial examples of the use of tracers
Describe how tracers are used in industry
Explain why gamma radiation is used in an industrial tracer
Recall that alpha sources are used in some smoke detectors
Explain how a smoke detector with an alpha source works
Key Words:
background radiation • cosmic rays • radioisotope • alpha • decay • tracer • gamma
Background radiation:
Granite rocks contain small amounts of radioactive uranium. When uranium decays it emits radon gas which is also radioactive. Wales, Devon, Cornwall. Lots of granite!!
Tracers
Radioisotopes are used as tracers in industry, research and medicine.
Tracers are used to: Detect leaks or blockages in underground pipes Find the routes of underground pipes Track dispersal of waste Monitor the uptake of fertilisers in plants Check for a blockage in a patient’s blood vessel
Locating a leak/blockage A very small amount of a suitable radioisotope is put
into the pipe A detector is passed along the ground above the path
of the pipe to track the progress of the radioisotope An increase in the activity is detected in the region of
the leak or blockage and little or no activity is detected after this point.
Smoke alarms contain a weak source of alpha radiation.
How can radiation detect a fire?
The alpha particles ionize the air.
If there is smoke present, it interacts with the ions produced by the alpha particles and ionization is reduced.
This means that less current is flowing through the air, which causes the alarm to sound.
α
α
smoke particle
Success CriteriaGrade E Grade C Grade A
Recall the main sources of background radiation
Recall background radiation can come from man-made sources and waste products
Evaluate the relative significance of sources of background radiation
Recall industrial examples of the use of tracers
Describe how tracers are used in industry
Explain why gamma radiation is used in an industrial tracer
Recall that alpha sources are used in some smoke detectors
Explain how a smoke detector with an alpha source works
Key Words:
background radiation • cosmic rays • radioisotope • alpha • decay • tracer • gamma