JACEE emulsion chambers for studying the energy spectra of high energy cosmic ray protons and helium

Abstract Emulsion chambers are being used in a series of stratospheric balloon flights to study nuclear interactions, charge composition, and energy spectra of cosmic ray nuclei over the energy range 10 12 –10 15 eV. Charge identification involves grain, gap, and/or delta-ray counting in emulsion plates having different sensitivities on two sides of an acrylic base. Electromagnetic cascade energies are measured with resolutions of about 25% by the three-dimensional track counting method. This report describes the apparatus, the measurement techniques, and the analysis methods used to determine the primary proton and helium spectra.