CHEP Particle Astrophysics Seminar

TRACER
(Transition Radiation Array for Cosmic Energetic Radiation)

Patrick (Jojo) Boyle

Kavli Institute for Cosmological Physics
University of Chicago

The individual energy spectra of heavy cosmic rays are poorly known above a TeV/nucleon. At these energies cosmic rays carry an important imprint of the acceleration and propagation mechanisms allowing one to probe possible sources of these cosmic rays. Extending the energy range will also enable overlap with measurements from the ground, allowing for a more definitive understanding of air-shower development.

TRACER is currently the largest detector system for direct measurements of cosmic-ray nuclei on balloons. In a 14 day Antarctic balloon flight TRACER has extended the energy spectra of heavy cosmic ray nuclei to beyond 10¹⁴ eV per particle.

In this talk I will discuss TRACER in terms of design and performance and will compare our results with previous measurements in space and on balloons, with interpretations of air shower data and also constraints on models of cosmic-ray propagation through the Galaxy. TRACER is currently being readied for an additional flight around the Arctic Circle in 2006.