Question

The mass of a muon is 207 times the electron mass; the average lifetime of muons at rest is 2.21 μs. In a certain experiment, muons moving through a laboratory are measured to have an average lifetime of 7.04 μs. For the moving muons, what are (a) β (b) K, and (c) p? The rest energy of the electron is 0.511 MeV.

Answer 1

Given, average lifetime of muons at rest is To = 2.21μs

Average lifetime of moving muons, T = 7.04μs

mass of muon = 207 mass of electron

a)

rest mass energy of an electron is 0.511 MeV.

`T =(T_o)/(√(1-\beta^2))`

Substitute the values:

`7.04 =(2.21)/(√(1-\beta^2))\\ \beta^2 = 0.90146\\ \beta = 0.95`

b) K = (γ-1) m₀c²

`\gamma = (1)/(√(1-\beta^2)) = 3.185`

K = (3.185-1) (207 ×9.1×10⁻³¹) (3×10⁸)² = 3.7×10⁻¹¹J

c) p = γmv = (3.185)((207 ×9.1×10⁻³¹)(0.95×3×10⁸)= 1.71×10⁻¹⁹ N/s