Investigating radioactivity (practical)

Question 1

Describe the investigation of the penetration of radiation.

Answer 1

1. You can detect ionising radiation with a
   Geiger-Muller detector. A Geiger-Muller
   detector gives a count rate.
2. Set up the equipment as shown on the
   right, so that when nothing is place
   between the source and detector, the
   counter records a high count rate
3. Remove the source to measure the
   background count over a time period
   (e.g 30 seconds). Divide your count by
   the time period to get a background
   count rate (in counts per second). Do
   this three times and find the mean.
   Subtract this from all your results
4. Replace the source and measure the
   count rate (minus the background count
   rate) with no material present three
   times and take a mean. Then insert
   different materials between the source
   and detector. Record the count rate for
   each material three times and find the
   mean.
5. If the count rate remains about the same
   when the material is inserted then the
   radiation can penetrate the material. If it
   drops by a large amount, then the
   radiation is being absorbed and blocked
   by the material. If it drops to zero after
   the background count is subtracted, the
   radiation is being completely absorbed
6. Repeat this experiment with different
   sources to investigate the penetrations of
   different kinds of radiation.

Question 2

Name three precautions when using radioactive sources.

Answer 2

Keep in a lead-lined box when not in use.
Picked up using long-handled tongs or forceps
keep a safe distance from them, don’t point them at someone.

Question 3

Describe the investigation of the penetration of radiation. (simplified M.S)

Answer 3

1. Set up an emitter of beta-radiation in line with a detector
2. Arrange them so that the sheets of lead, aluminium and paper can
   be placed between them.
3. Beta radiation penetrates paper
4. Beta radiation is absorbed / stopped by lead and aluminium