Muons

Muons are heavy elementary particles with negative charge. The muons are created when cosmic rays collide with nitrogen in the upper atmosphere and have a mean lifetime of 2.2 μs. When the muons continue to travel through the atmosphere, they lose different amounts of energy depending on what elements they pass though. This has been used for detecting secret chambers in pyramids. Because of the muons’ short lifetime, only about 0.003 % of the muons should make it down to the Earth, which makes approximately 20 muons an hour. However, approximately 10,000 muons hit one square metre down on Earth, every second. This wouldn’t be if it wasn’t for the time dilation due to them travelling with nearly the speed of light. 

Research has shown a correlation between high temperatures in the stratosphere and a high amount of muons per area and time unit. Scientists are not sure why that is. One explanation they’ve found is that when the atmosphere is thick and cold cosmic radiation continues to interact and doesn’t turn into as many muons as when the atmosphere is warmer. Another explanation might be that when there are more greenhouse gases in the atmosphere the muons lose more energy on their way down to the ground, since they lose more energy passing through heavier molecules, such as carbon dioxide, than lighter ones, such as oxygen or nitrogen.

By measuring the muon intensity, we want to contribute to fundamental research on the correlation between high muon intensities and higher temperatures in the stratosphere. However, most muon detectors used are expensive and difficult to manufacture. With a small, can-sized muon detector which can be integrated wherever, the muon intensity can be measured in all kinds of situations.