Spin rotation of the planar channeled antiproton in bent crystal

In the present paper, we derive the exact solution of the BMT equation for the spin rotation of relativistic negatively charged particles passing through a thin bent crystal in the regime of planar channeling. It is shown that during the passage through the crystal a particle polarization vector oscillates. If one takes into account, the energy and angular divergence of the initial particle beam these oscillations die fast with particle penetration length into a crystal, and particle spin rotation is determined by the crystal bending angle.