In our everyday experience, we are oblivious to the cosmic rays passing through our homes and our bodies. These particles, mainly from outer space, are detectable only via their interactions; charged particles leave trails of ionisation and neutral particles pass through matter causing no effect until they interact to produce charged particles which are then detected via their ionisation.
Despite this apparent intangibility, charged particles can be detected in plastic scintillation counters and we can then determine basic characteristics of these cosmic rays. We can investigate phenomena which seem at first sight beyond our reach.
Educational scenario objectives:
During the scenario, participants will:
1. investigate the origin of cosmic rays (primary cosmic rays)
2. will realise that the primary cosmic rays interact high in the Earth’s atmosphere
producing showers of secondary particles
3. appreciate that these secondary cosmic rays comprise mainly muons (200 times heavier
than the electron and with a lifetime of just over 2 μs )
4. understand how charged particles interact as they pass through matter, in particular how
they may be detected by the trails of ionisation which they produce
5. discuss how these trails of ionisation, constituting tiny amounts of electrical charge, may be detected
6. understand how a charged particle may be detected by using a scintillation counter i.e. a
scintillator and photomultiplier tube combined
7. convince themselves of the basic principles of electronic detection: although most signals
from the photomultiplier tubes comprise noise pulses, one can detect particles by demanding a coincidence of two or more scintillation counters.
8. using several scintillation counters, set up a cosmic ray telescope and measure the rate
of incident cosmic rays
9. with the counters mounted vertically one above another, determine how the measured rate varies with the separation of the counters. How precisely can one define the direction of the incoming particles?
10. with the counters lying in a plane, measure the coincidence rate and determine how the
rate changes as the horizontal separation of the counters increases
11. devise a programme of experiments e.g. repeat the measurements at different times of
the day, indoors and outdoors, in different parts of the building
12. look for correlations of the measured rate with external factors like air temperature and
pressure
13. by measuring delayed coincidences between counters in a vertical stack, determine the
muon lifetime
14. discuss how these measurements agree (or not) with the known properties of cosmic
rays
15. summarise their data, describe to other groups what they have done and, if possible,
compare results
16. understand the connection between their cosmic ray studies and current particle physics
experiments
Download the PDF complete version by clicking on the following link: educational_content_cosmic_rays.pdf
• Guide: activities that are possible to do
• Details: feasible experiments
Educational Content developed by Birmingham University
Validated by Discover the Cosmos + Cosmic rays
Last update | 20/06/2013