Cosmic muon detector


#07 Periastra : Participants : John Berman

Where do Cosmic Muons come from?

1 - From outside the solar system e.g. Supernovae - exploding massive stars - are one source of cosmic rays.
2. From within the solar system e.g. Solar cosmic radiation, high energy particles (predominantly protons) emitted from the sun.

Muons are generated in the Earth's upper atmosphere by cosmic rays (particles) colliding with atomic nuclei of molecules in the air. The muon only has a lifetime of 2 millionths of a second so, given that they will travel over 10,20, 30 km how are there any left to detect at the surface?. How are we able to detect them?

Time dilation

A muon moves at about 99.999% the speed of light, every 660 meters outside of its reference frame will appear as though it's just 3 meters in length. A journey of 100 km down to the surface would appear to be a journey of 450 meters in the muon's reference time frame, taking up just 1.5 microseconds of time according to the muon's clock.

About the detector

There are several ways to detect them, some of which are quite expensive

I have opted for a Geiger Müller (GM) tube, they are low cost and require relatively simple electronics A GM tube will detect alpha particles, beta particles, gamma rays and Cosmic Muons If we have one or more detectors then we can stack them, an event registered on all GM tubes simultaneously will be a muon and not background.

These two detectors are currently working independently as I need to build the interface electronics. Each time an event is registered the blue light flashes, once the interface is built, I can then determine simultaneous events which will be Muons - Currently the detectors are registering alpha particles, beta particles, gamma rays and Cosmic Muons

John will also be showing a video of meteor detection and examples of his astro-photography.