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.
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.