Relativistic Muons

A beam of muons is maintained in a circular orbit by a uniform magnetic field. It is observed that half of the muons decay during each full orbit. Note that the muons travel at velocities whereby relativistic effects are significant. Find the strength of the magnetic field (in Teslas)

Details: The mass of the muon is $1.88\times10^{-28}$ kg, its charge is $-1.602\times10^{-19}$ C, and its half-life is 1.523 $\mu$ s. Neglect energy loss by radiation.