For many decades, ultra-high energy charged particles have been a puzzle for
particle physicists and astrophysicists. Nor the sites of production, nor the
mechanism responsible for the generation of these ultra-energetic `cosmic rays'
(CR) are currently known. They seem to arrive from random direction in the sky,
although the most energetic ones, which are not deflected much by the magnetic
fields, are supposed to point towards their source with good accuracy.