THE "standard theory" of cosmic rays -high-energy particles .that continually bombard the Earth from space -postulates that the rays) actually charged nuclei, are accelerated by supernova: remnants. This was first suggested in the early 1960s by Ginzburg and Syrovatskii, who estimated that,the conversion of just 1% of the kinetic energy of the expanding remnant would supply all of the galactic cosmic rays, Supernova remnants : (SNR) can expand with velocities in excess of 10000 kins and the acceleration is thought.to occur at shocks in the expanding shell of the remnant. Although this model can explain the acceleration of nuclei with energies of up to at least 1014 eV,our Galaxy is believed to produce all of the cosmic rays up to 1018-10!" eV. (Higher energy particles are thought to come from extra-galactic sources.)
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