High-energy electron observations from 30 GeV to 3 TeV with emulsion chambers

We have observed high-energy cosmic-ray electrons from 30 GeV to 3 TeV with emulsion chambers at balloon altitudes, accumulating the total exposure of 8.19 m2.sr.day. In the observations, we have carried out particle identification event by event with a proton rejection power of 1×10⁵ in TeV region, which is one of the outstanding capabilities of the emulsion chambers. The performance of the emulsion chambers was examined by accelerator beam tests at CERN-SPS and Monte-Carlo simulations. We also estimated the atmospheric electron spectra in a reliable way, and carried out on-board calibrations by using flight data. In the study of cosmic-ray electrons, it is indicated that highenergy electrons above a few 100 GeV are a powerful probe to identify nearby cosmic-ray sources and search for dark matter. In this paper, we present the final result of energy spectrum of high-energy cosmic-ray electrons observed with emulsion chambers in the energy range from 30 GeV to 3 TeV.