Measuring The Cosmic-ray Spectral Knee With Low Count Statistics
Abstract
Most cosmic-ray particles with energies above a few GeV are believed to be accelerated by supernova shocks in the Galaxy. The shock acceleration models, in their simplest forms, predict a power law spectrum which has been confirmed by many balloon and space-borne experiments. Supernova shocks can accelerate protons to a maximum energy of E_max≈ 10^5 GeV. Ground based detectors, however, have observed particles of much higher energies, albeit with a steepenning in the spectrum above ≈ 10^6 GeV (the ``Knee'' in the spectrum). The origin of the ultra high energy part of the spectrum is still a mystery and these observations have cast some doubt about the supernova shock acceleration model of cosmic rays altogether. To test the maximum energy reach prediction of supernova shocks, it is essential to use detectors with good charge resolution to separate protons from heavier nuclei. Such detectors must be placed above the atmosphere and for logistic reasons will necessarily have a limited size and therefore limited statistics near the Knee. In this paper we will discuss the statistical techniques for ascertaining spectral features with low count Poisson statistics.
- Publication:
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APS April Meeting Abstracts
- Pub Date:
- April 2002
- Bibcode:
- 2002APS..APRB17037S