Muons are one of the twelve fundamental particle types of matter, having relatively long free-particle lifetime. A muon decays into three other light particles (leptons) through action of the “weak” force, transmitted by the so-called “heavy photons” - bosons W+/W-. Muons are present in the secondary cosmic ray showers in the atmosphere and reach the sea level. By detecting the delay time between arrival of the muon and an appearance of the decay electron in our single scintillation detector, we measured the muon’s average lifetime at rest in the material of our detector. This compares well with the established value. From the lifetime, using the Standard Model of Fundamental Particles’ (SM) relations and an experimental value for masses of W boson MW and of the muon mμ, we calculated the universal weak and electric charges and the vacuum expectation value of the Higgs field. We measured the sea-level fluxes of both low-energy (below 140 MeV) and high-energy muons and found that they must be energy-independent in the lower part of their spectrum. We also found the shapes of the energy spectra of low-energy muons and of their decay electrons. We were unsuccessful in our attempt to measure the stopping power of muons in lead shielding.

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Introduction Muons (denoted by µ) are leptons, fundamental particles that also include electrons (denoted by e), tau-particles and their three neutrinos (denoted by υ, with a respective subscript), which cannot be subdivided. They are not subject to the nuclear-strength interaction. Muons are constantly being created by cosmic-ray high-energy protons, which collide with nuclei of the upper atmosphere where they produce showers of unstable non-elementary pions, which in turn decay into muons. The muon is like electron but is 200 times heavier and is thus itself unstable. It decays in microseconds (10-6 s) into three new particles: an electron, an electron antineutrino and a muon neutrino. (Physics Open Lab). Figure 1. Artistic rendering of the muon production by cosmic rays in the atmosphere Figure 2. Rendering of pion creation and subsequent decay into a muon and a neutrino.

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Pich, A. (2000, January 27). Lessons learnt from the heavy tau lepton. Retrieved from http://cerncourier.com/cws/article/cern/28162 Figure 14. Ballett, P., Pascoli, S. (2012, September 12). L–E_μ and the LENF. Retrieved from http://www.ippp.dur.ac.uk/~ballett/LENF/ and hep-ph/1201.6299 Figure 15. Griffith, David (2008). Introduction to Elementary Particles. Wiley-VCH Verlag. Figure 21. Physics Open Lab (2016, January 10). Cosmic Ray Muons & Muon Lifetime. Retrieved from http://physicsopenlab.org/2016/01/10/cosmic-muons-decay/