Spectra of H and HE measured in a series of annual flights

Abstract We have obtained the absolute spectra of H and He by analyzing data collected by a series of annual flights of the Balloon borne Experiment with a Superconducting solenoid Spectrometer payload. This instrument is configured with a cylindrical magnet, a Time-of-Flight system, a set of cylindrical multiwire drift chambers inside and outside the magnet, and a central tracking device Jet chamber. The analysis involves Monte Carlo simulations of the effective geometry factor, studies of various efficiencies, and corrections for the ionization energy loss, attenuation and atmospheric secondaries. Variations of the H and He fluxes at different levels of solar modulation are presented.