Balloon-borne Experiment with Superconducting Spectrometer
***BESS-Polar (latest instrument in the series)***
was launched from Williams Field, McMurdo, Antarctica at ~1 am EST 12/13/04
and terminated after a successful flight at ~5 pm EST 12/21/04
after ~8 days, 12 hours at float altitude
The current incarnation of the BESS instrument, BESS-Polar, is similar in design to previous BESS instruments, but is completely new with an ultra-thin magnet developed at the High Energy Accelerator Research Organization (KEK) and configured to minimize the amount of material in the cosmic ray beam, so as to allow the lowest energy measurements of antiprotons. BESS-Polar has the largest geometry factor of any balloon-borne magnet spectrometer currently flying, and is ideally suited to statistics-limited studies of Z=1 and Z=2 components - identifying antiprotons, and searching for antihelium nuclei in the cosmic radiation. BESS-Polar has a geometrical acceptance of 0.3 m2-sr, an aerogel Cherenkov counter with index of refraction n=1.02 and a time-of-flight system with 150 ps resolution, capable of identifying antiprotons over the energy range from 100 MeV to 4.2 GeV. BESS-Polar is scheduled to make its maiden flight from McMurdo, Antarctica in December 2004. A second flight at the time of minimum solar activity is planned for 2007. The extended data-taking time of long duration flights, the increased event efficiency of the BESS-Polar configuration and the low geomagnetic cutoff should together allow an improvement factor of more than 20 over existing low-energy antiproton data.
Dr. John Mitchell leads the U.S. BESS program along with Drs. Thomas Hams, Alex Moiseev, Makoto Sasaki and Robert Streitmatter at NASA/Goddard, Dr. Jon Ormes at the University of Denver, and Drs. Eun-Suk Seo and MooHyan Lee at the University of Maryland. The BESS project in Japan is under the leadership of Dr. Akira Yamamoto, along with Dr. Tetsuya Yoshida at KEK. Other members of the BESS collaboration in Japan are from the University of Tokyo, Kobe University and the Institute for Space and Aeronautical Science (ISAS/JAXA). The BESS-Polar magnet with gas detectors for particle trajectory measurement and associated electronics were designed and constructed in Japan. The time-of-flight system and aerogel Cherenkov detector and associated electronics were designed and constructed by the U.S. BESS-Polar team. Integration of the new BESS-Polar instrument took place at Goddard Space Flight Center during the past year. Final test and integration was done in Palestine, TX in August/September 2004. The U.S. BESS activities are supported by NASA's Sustaining Research and Technology (SR&T) program.
This page was authored by Dr. Robert Streitmatter of the Laboratory for High Energy Astrophysics (LHEA) at NASA's GSFC.