A beam of protons with speed  $4\times {10}^{5}m{s}^{-1}$ enters a uniform magnetic field of 0.3T at an angle of 60º to the magnetic field. The pitch of the resulting helical path of protons is close to: (Mass of the proton  $1.67\times {10}^{-27}kg$,  charge of the proton $1.69\times {10}^{-19}$ C)