News of the WeekAstrophysics

Ultraenergetic Particles Slip Past Cosmic Cutoff

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Science  14 Aug 1998:
Vol. 281, Issue 5379, pp. 891-892
DOI: 10.1126/science.281.5379.891b

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Summary

TOKYO-- Every so often, a cosmic ray slams into the atmosphere packing 100 million times the energies reached in the world's largest particle accelerators--the energy of a brick falling from a table packed into a single subatomic particle--but the number detected has been so small that they might have been the few outliers at the very top of the cosmic ray energy spectrum. Now, however, the Japan-based Akeno Giant Air Shower Array collaboration has recorded a further handful of ultraenergetic events--enough to conclude that the upper limit to cosmic ray energies is not yet in sight. And researchers expect more such sightings from new detectors scheduled to come on line in the next few years.