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Muon Decay Experiment. John Klumpp And Ainsley Niemkiewicz. What Are Muons?. Fundamental particles Carry charge of +/- 1 Essentially heavy electrons Inherently unstable Decay into electrons and neutrinos. Where Do They Come From?. Cosmic rays collide with matter in the upper atmosphere
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Muon Decay Experiment John Klumpp And Ainsley Niemkiewicz
What Are Muons? • Fundamental particles • Carry charge of +/- 1 • Essentially heavy electrons • Inherently unstable • Decay into electrons and neutrinos
Where Do They Come From? • Cosmic rays collide with matter in the upper atmosphere • Many fundamental particles produced • Only muons make it to the surface. Why?-High mass-Time dilation
What Does Relativity Have To Do With It? • Muons only survive about 2.2μs in lab frame • 2.2μs * Speed of Light = .66 meters • But the muons are not in the lab frame • From the lab frame their clocks run slower, so they live longer • From the muon’s reference frame the distance is shorter • Measuring lifetimes confirms theory of relativity
How Do We Detect Them? • Muons captured in scintillation detector • Flash of light produced when muons are stopped
How Do We Measure Lifetime? • Another flash of light is produced by detector when muon decays • Time between capture flash and decay flash is the muon lifetime
How Do We Calculate Mean Lifetime • Muons decay randomly, so many samples are needed • Collect samples for 48 hours • Fit data to exponential decay equation
Data • Calibration 40 channels = 1.28 μs • Compress data from 512 channels to 64 channels. This helps MatLab’s Gaussian approximation work better • 10 channels = 1.28 μs • Trial 1 (48 hour trial): F(x) = 172.9e-x/71.41 + 16.19 channels • Trial 2 (12 hour trial):F(x) = 109.4e-x/74.37 + 9.655 channels
Where’s The Mean Lifetime? • The exponential decay equation is • In this equation, b is the average lifetime. • In trial 1, b = 71.41 channels*1.28µs/40 channels = 2.38±0.13µs • Similarly, in trial 2,b = 74.37*1.28/40 = 2.29±0.13µs
Sources of Uncertainty • Background radiation • Some muons don’t decay • Some decays may not be detected • Deletion of first fifteen channels
Conclusion • Simple, accurate experiment • Demonstrates random nature of particle decay • Confirms relativistic time dilation