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Radioactivity and Particles

This document outlines a practical experiment for investigating the penetration powers of alpha, beta, and gamma radiation using various absorbers and a Geiger counter. It includes detailed equipment lists, a step-by-step method for conducting the experiment, tips for improving accuracy, and essential safety precautions. The goal is to measure and compare the count rates of different radiation types as they pass through various materials.

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26 views3 pages

Radioactivity and Particles

This document outlines a practical experiment for investigating the penetration powers of alpha, beta, and gamma radiation using various absorbers and a Geiger counter. It includes detailed equipment lists, a step-by-step method for conducting the experiment, tips for improving accuracy, and essential safety precautions. The goal is to measure and compare the count rates of different radiation types as they pass through various materials.

Uploaded by

Flora Silence
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Edexcel Physics IGCSE

Chapter 7: Radioactivity and Particles


Practical Notes

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Investigate the Penetration Powers of Different Types of Radiation Using
Either Radioactive Sources or Simulations

Equipment
● Radioactive sources:
○ Alpha source
○ Beta source
○ Gamma source
● Geiger counter
● Stopwatch
● Ruler
● Absorbers such as:
○ Plastic
○ Aluminium
○ Steel
○ Lead
○ Paper

Method
1. Set up the Geiger counter without any of the radioactive sources nearby and record
the background activity over a period of about 15 minutes and calculate the count
rate in counts per minute (divide the total counts by the number of minutes).
2. Set up a clamp stand directly in front of where the source will be - this will be used
to attach your absorbers to.
3. Place the Geiger counter around 5cm from where the source will be, pointing
towards the clamp stand.
4. Move the first radioactive source into position and with no absorbers in place,
record the number counts over a 5 minute period and calculate the count rate.
5. Attach different absorbers to the clamp stand, one at a time, and repeat.
6. Correct all count-rate readings for background radiation by subtracting the
background reading measured in step 1.
7. Repeat for the other two sources and then compare the count rates for each source
with each different absorber.
8. A higher count rate for a given material means that more radiation has passed
through the absorber and so the radiation type is more penetrating.

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Tips
● To develop this experiment further, you could experiment with different thicknesses
of absorbers to see how the penetration varies for each type of radiation.
● Repeat readings are beneficial in this experiment since it is not unusual to get
anomalous results due to miscounting or random variation.
● If readings for all combinations seem particularly low, the radioactive source may be
too old and may have become too inactive to get easily observable readings - a
new source may be required or count rates should be taken over a longer period of
time.
● Consider the best way to display your results - you could construct bar charts for
each material or you could construct them for each radiation type.

Safety Precautions
● Ensure radiation in use signs are clearly displayed, and that all those in the
laboratory are aware that radiation is in use.
● When not in use, ensure that the radioactive emitters are stored in their containers
to reduce unnecessary exposure.
● Use radioactive sources that have a half-life of a few years and have been
approved for school use.
● Never handle the sources directly, always use long-armed tongs with an extended
arm to maximise the distance you are from the source.
● A teacher/technician should always be present when working with radioactive
sources in the lab.

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