Stochastic particle acceleration by a pair of slow shocks

We consider a stochastic acceleration mechanism of charged particles working at a pair of slow MHD shocks. The dominant acceleration occurs when a particle has a curvature drift at the shock front, which is parallel to the convection electric field. Since this acceleration mechanism works only on particles crossing the shock front, scattering agents in the upstream region are needed for the successive acceleration. The final energy spectrum, which is determined by the balance among the acceleration, deceleration, and escape processes, is softer than the power law. We suggest that this new acceleration mechanism in the reconnection region can provide the possibility to create high-energy particles in the magnetotail.