The Latest Results on High Energy Cosmic Rays

Abstract

Four detectors operate currently in space exploring a new and exciting frontier in physics research: AMS, CALET, DAMPE, and ISS-CREAM. Of these four detectors AMS is the only magnetic spectrometer. Precision measurements by AMS of the fluxes of cosmic ray positrons, electrons, antiprotons, protons and light nuclei as well as their ratios reveal several unexpected and intriguing features. The presented measurements extend the energy range of the previous observations with much increased precision. The new results show that the positron flux rises from ~10 GeV above the rate expected from cosmic ray collisions with interstellar gas and then exhibits a sharp drop off above ~300 GeV. This is consistent with a new source of high energy positrons. Surprisingly, in this rigidity (i.e. momentum divided by charge) range the spectral indices of cosmic ray nuclei experience progressive hardening over the rigidity interval of few hundred GV. This hardening is more pronounced for the secondary nuclei such as lithium, beryllium, and boron than for the primary nuclei helium, carbon and oxygen. Most importantly, AMS continues studies of complex antimatter candidates with stringent detector verification and collection of additional data.