International School of Cosmic Ray Astrophysics

16^th  Course: "Gamma Ray and Cosmic Ray Astrophysics: From below GeV to beyond EeV Energies"

 5-12 July 2008
Ettore Majorana Centre
Erice, Sicily, Italy

Topic: The BESS-Polar Program and the Search for Antimatter.
Lecturer: Thomas Hams

The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) program is searching for antimatter in the galactic cosmic radiation by precisely measuring the elemental and isotopic composition of the light cosmic ray component. The experiment is a highly successful US-Japanese collaboration and over the past 15 years, the BESS payload has had eight low geomagnetic cutoff, northern latitude flights and two long duration balloon flights from Antarctica. The BESS-Polar instrument has just completed its second such long-duration balloon flight of 24.5 days, which occurred between December 2007 and January 2008.

We will review the BESS program and report the latest results including the antiproton and proton spectra measured in the BESS-Polar I flight, the search for cosmic antinuclei, and the status of the BESS-Polar II analysis.