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The Transition Radiation Array for Cosmic Energetic Radiation (TRACER) is a new instrument for direct, balloon borne measurements of heavy cosmic ray nuclei (oxygen to iron) in the energy range from 1013 to several 1014 eV per nucleus.

TRACER had a successful 14 day Antarctic flight in 2003, 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).

The ground track of the balloon is available here or on the offical NASA/NSBF page.

TRACER launched from the Ross Ice Shelf, near McMurdo Station, on a 39 million cubic foot balloon on Friday 12th December 19:09 local time (6:09 GMT) and was terminated on the eastern Polar Plateau on Saturday 27th December 03:40 local time(14:40 GMT).

The direction and speed of the balloon were at all times at the mercy of the prevailing winds over the continent. The balloon returned to within 80 miles of its launch site after a journey of two weeks circumnavigating the Antarctic continent.

Science

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 (oxygen to iron) in the energy range from 1013 to several 1014 eV per nucleus.

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

Antarctic LDB Mission 2003

TRACER was designed to fly on a long duration balloon (LDB) around the northern pole. The instrument is suspended below a 40 million cubic balloon filled with Helium. Once launched the balloon will rise to an altitude of 125,000ft (above 99% of the atmosphere) for a period of 14 - 30 days. By climbing above the atmosphere one tries to sample the cosmic rays before they are destroyed by interactions with the atmosphere.

Before launching an LDB balloon one must certify the instrument during a 1 day engineering flight in the continental USA. TRACER had its first balloon flight in September 1999 from Ft. Sumner/New Mexico. The instrument design worked well allowing the measurement of the intensities of heavy cosmic ray nuclei Oxygen, Magnesium, Silicon & Iron up to 1 TeV/nucleon. The results from the 1 day flight are consistent with previous measurements made by CRN in an energy regime with few comparable measurements. (see our results section).

TRACER Launch (12/12/03)

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