TRACER

The Transition Radiation Array for Cosmic Energetic Radiation (TRACER) is a new instrument for direct, balloon borne measurements of single element heavy cosmic ray nuclei (boron to iron) in the energy range from 10¹³ to several 10¹⁵ eV per nucleus.

TRACER recently completed its third flight, making a four and a half day journey from Kiruna, Sweden to Sommerset Island, Canada. Improvements to TRACER for this flight are the extension of the dynamic range of the Transition Radiation Detector to include Boron and Carbon and the addition of a second Cerenkov Counter to increase Charge Resolution.

Days after the conclusion of its third flight, an intact TRACER was successfully recovered from Somerset Island, Canada.

In 2003 TRACER had a successful 14 day Antarctic flight, traversing some 5,000 miles around the South Pole at an average elevation of 125,000 ft. TRACER sampled over 50 Million heavy Cosmic Rays during the 2003 flight (Carbon through Iron). Results from this flight are available on our results page and have been presented at conferences including the 2005 APS, ICRC and TRD workshop and the 2006 COSPAR conference..

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. By increasing our knowledge at higher energies we are able to overlap with measurements from the ground to allow a better understanding of airshower development.

The Transition Radiation Array for Cosmic Energetic Radiation (TRACER) is a new instrument for direct, balloon borne measurements of heavy cosmic ray nuclei (boron to iron) in the energy range from 10¹³ to several 10¹⁵ eV per nucleus.

The instrument has been developed and constructed at the University of Chicago under support from NASA.