Two solenoids are nested coaxially such that their magnetic fields point in opposite directions. Treat the solenoids as ideal. The outer one has a radius of 20mm, and the radius of the inner solenoid is 10mm. The length, number of turns, and current of the outer solenoid are, respectively, 21.1cm, 507turns, and 4.47A. For the inner solenoid the corresponding quantities are 18.9cm, 395turns, and 1.53A. The elementary charge is 1.6021019C, the mass of the proton is 1.6731027kg, and the vacuum permeability constant has the value4107Tm/A.

At what speed 1 should a proton be traveling, inside the apparatus and perpendicular to the magnetic field, if it is to orbit the axis of the solenoids at a radius of5.99mm?