Spin rotation associated with deflection of relativistic charged particle in an electric field

The connection between the spin rotation and the curvature of the trajectory of a relativistic charged particle travelling in an electric field is found. It is shown that in this case the momentary immediate angular velocities of the spin precession and momentum rotation are parallel. This result is applied to the plane channeling of high-energy protons and positrons in curved crystals. The same consideration is used to study the rotation of the polarization vector of the relativistic particle possessing an arbitrary magnetic moment in small-angle Coulomb scattering