A New Measurement of the Intensities of the Heavy Primary Cosmic‐Ray Nuclei around 1 TeV amu−1

We describe a new measurement of the intensities of the heavy primary cosmic-ray nuclei O, Ne, Mg, Si, and Fe from 10 GeV amu-1 to energies beyond 1 TeV amu-1. The measurement was conducted in 1999 during a 1 day test flight of the Transition Radiation Array for Cosmic Energetic Radiation (TRACER), a new cosmic-ray telescope designed for long-duration balloon flights. TRACER uses an array of thin-walled single-wire proportional tubes to determine the particle Lorentz factor from measurements of specific ionization and transition radiation. The nuclear charge is obtained with plastic scintillators, and low-energy background is identified with an acrylic Cerenkov counter. The results of this observation are consistent with previous measurements in this energy region. The current statistical limitations should be greatly improved with the planned long-duration exposure of TRACER.