A proton moves perpendicular to a uniform magnetic field $\mathbf{B}$ at a speed of $1.00 \times 10^{7} \mathrm{m} / \mathrm{s}$ and experiences an acceleration of $2.00 \times 10^{13} \mathrm{m} / \mathrm{s}^{2}$ in the positive $x$ direction when its velocity is in the positive $z$ direction. Determine the magnitude and direction of the field.