A proton with a kinetic energy of $2.0 ~\mathrm{eV}$ moves into a region of uniform magnetic field of magnitude $\frac{\pi}{2} \times 10^{-3} \mathrm{~T}$. The angle between the direction of magnetic field and velocity of proton is $60^{\circ}$. The pitch of the helical path taken by the proton is __________ $\mathrm{cm}$. (Take, mass of proton $=1.6 \times 10^{-27} \mathrm{~kg}$ and Charge on proton $=1.6 \times 10^{-19} \mathrm{C}$ ).