Muon Particle - Myon

Electrically charged unstable elementary particle with a rest energy of 105.658 MeV corresponding to 206.786 times the rest energy of an electron (0.511 MeV). The muon has an average half-life of 2.2 · 10-6 s. The muon belongs to the elementary particle group of the leptons.

Most cosmic rays are protons, which are abundant in the universe.
Primary cosmic rays are particles such as a single proton (nuclei of hydrogen; about 90% of all cosmic rays) up to an iron nucleus and beyond, but being typically protons and alpha particles (identical to helium nucleii; majority of the remaining 10%) traveling through the interstellar medium. Most of these originate outside of our solar system (galactic cosmic rays GCR's - i.e. from Supernovae), but some of them come from the sun.

When these primary cosmic rays hit Earth's atmosphere at around 30,000m above the surface, the impacts cause nuclear reactions which produce pions. These pions decay into a muon and muon neutrino (= antineutrino) at about 9000 m altitude, which rain down upon the surface of the earth, traveling at about 0.998c. Many muons decay on the way down into Neutrinos and an electron while others reach the surface, but there are still enough to be detected fairly easily. Actually, about 200 rain down on each square meter of Earth every second. Details about particle decay (pion-muon-neutrino-antineutrino).

The Project - Simple DIY (do-it-yourself) Cosmic Ray Detector
Muon Particle Experiment - Cosmic Ray Telescope

Detecting Cosmic Rays is easy! This website provides schematics for the whole muon experiment (electronics schematic, variable high voltage power supply schematic and a drawing for the detector assembly). Check the new cloud chamber page for a non-electronic way for particle detection and visualization.

We detect the muons by utilizing a homebrew Geiger-Müller detector. The Geiger counters are supplied by high voltage, which creates a very high electric field near the anode of the detectors. When a cosmic particle enters one detector, it strips off some electrons of some atoms. These electrons move towards the positively charged wires, are accelerated by the huge electric field and have enough energy to strip more electrons from other gas molecules. These electrons are accelerated too in order to strip more and more electrons. This electric avalanche consisting of more than a billion negative charges rains down on the positively charged wire, causing a current which flows into the simple detection circuit.

Since other particles are stimulating the detector aswell, we will use 2 detectors to avoid false detection. Other particles originating from i.e. terrestrial radiation will also cause a stimulation, but those particles have too less energy to penetrate both detectors. They will end up either in the first detector or shortly after it. So we simply have to look for almost instant detections in both detectors and consider this as successful detection.

Be very careful when handling high voltages!
cosmicrays.org cannot be held liable for damage of any sort!