Muons are elementary particles similar to the electron but with a mass over 200 times heavier. Muons are unstable and have an average lifetime of 2.2 µs, which is longer than many subatomic particles.
Muons are primarily produced in the uppermost part of Earth’s atmosphere when cosmic rays collide with molecules in the atmosphere. Each minute every square meter of the earth’s surface is hit by around 10,000 muons.
The Complete Muon Observatory is designed to allow you and your students to study these particles. You can detect cosmic rays and demonstrate the angular dependence with this muon observatory that can be configured for either Shower Mode or Telescope Mode.
How it Works
The apparatus can be configured for either Shower Mode or Telescope Mode:
- In the Shower Mode setup, a shower is recorded as a concidence event from three GM tubes arranged in a triangle. This geometry ensures that no single particle can be detected in all three tubes. Production of showers may be enhanced by allowing the radiation to pass through something that is slightly “thicker” than air (multiple steel plates are used). In shower mode you will typically align the muon observatory vertically. Measurement periods are approximately one day long.
- In Telescope Mode three GM tubes are arranged in a line, and if a muon passes through all tubes in the setup, a pulse is outpus from the coincidence box. The angle of the telescope can be varied to detect the angular distribution of the muons.
The Complete Muon Observatory contains the Muon Observatory as well as a Geiger Tube, Coincidence Box, and Geiger Counter. Here is a brief description of some of those component pieces.
Large Area Geiger Tube (SF-7266):
The extra sensitive tube (28.6 mm mica window) is suitable for measurements of radon daughters, naturally radioactive minerals, cosmic radiation and other applications where a greater area of sensitivity, greater solid angle or more sensitive volume are desirable. This tube is supplied with a forked holder with a mounting post.
Coincidence Box (SF-7269):
To register coincidence between the three GM tubes, a coincidence box is required. The output of the coincidence box goes to a Geiger Counter (SF-7268) which is set to count with manual start and stop.
Geiger Counter (SF-7268):
This Geiger counter can be set to start and stop manually and has a digital readout.