| Institution: | 1. National Aeronautics and Space Administration (NASA), Goddard Space Flight Center, Greenbelt, MD 20771, USA;2. High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan;3. Kobe University, Kobe, Hyogo 657-8501, Japan;4. Institute of Space and Astronautical Science (ISAS/JAXA), Sagamihara, Kanagawa 229-8501, Japan;5. University of Maryland, College Park, MD 20742, USA;6. The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan;g University of Denver, Denver, CO 80208, USA |
| Abstract: | In this paper, we report searches for antihelium in cosmic rays using two recently flown magnetic rigidity spectrometers. BESS-TeV had extended rigidity with an MDR of 1.4 TV and had a flight duration of one day. BESS-Polar was optimized for collecting power. It was flown for 8.5 days and had an MDR of 240 GV. The former flight allows us to explore a previously unexplored rigidity band and the latter flight yields a factor of three improvement in the overall BESS limit. No antihelium candidate was found in the rigidity ranges of 1–500 GV, and 0.6–20 GV, among 7 × 104 events taken with BESS-TeV, and 8 × 106 events taken with BESS-Polar, respectively. |
