The vicissitudes of "cannonballs": a response to criticisms by A.M.   Hillas and a brief review of our claims
  A.M. Hillas, in a review of the origins of cosmic rays, has recently criticized the "cannonball" (CB) model of cosmic rays and gamma-ray bursts. We respond to this critique and take the occasion to discuss the crucial question of particle acceleration in the CB model and in the generally accepted models. We also summarize our claims concerning the CB model. 
Arnon Dar and A. De Rujula