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CALET data of the cosmic-ray proton spectrum is open to public: unprecedented precision measurements

Proton flux measured by CALET, compared with other experimental results. In order to emphasize the structures in the spectrum which decreases rapidly as the energy increases, the y-axis shows the proton flux multiplied by E^2.7.

CALET, launched to the International Space Station in August 2015, is a calorimeter to measure cosmic rays and has been accumulating scientific data for over six years. CALET measured the spectrum of the cosmic-ray protons from 50 GeV to 60 TeV. The tables of the spectrum measured by CALET have become open to the public via DARTS in September 2022.
The observed proton spectrum features not only the hardening which has been observed in light nuclei such as helium, carbon, oxygen, but also a sharp softening starting around 10 TeV. It provides significant information for verifying models of the acceleration and propagation mechanisms of cosmic rays in the galaxy. Accordingly, the results were published in Physical Review Letters on September 1, 2022.

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(Oct. 2022)


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Last Modified: 13 October 2022