Details

Autor(en) / Beteiligte

• Abe, K
• Fuke, H
• Haino, S
• Hams, T
• Hasegawa, M
• Horikoshi, A
• Itazaki, A
• Kim, K C
• Kumazawa, T
• Kusumoto, A
• Lee, M H
• Makida, Y
• Matsuda, S
• Matsukawa, Y
• Matsumoto, K
• Mitchell, J W
• Myers, Z
• Nishimura, J
• Nozaki, M
• Orito, R
• Ormes, J F
• Sakai, K
• Sasaki, M
• Seo, E S
• Shikaze, Y
• Shinoda, R
• Streitmatter, R E
• Suzuki, J
• Takasugi, Y
• Takeuchi, K
• Tanaka, K
• Thakur, N
• Yamagami, T
• Yamamoto, A
• Yoshida, T
• Yoshimura, K

Titel

Search for antihelium with the BESS-Polar spectrometer

Ist Teil von

• Physical review letters, 2012-03, Vol.108 (13), p.131301-131301, Article 131301

Ort / Verlag

United States

Erscheinungsjahr

2012

Quelle

American Physical Society

Beschreibungen/Notizen

• In two long-duration balloon flights over Antarctica, the Balloon-borne Experiment with a Superconducting Spectrometer (BESS) collaboration has searched for antihelium in the cosmic radiation with the highest sensitivity reported. BESS-Polar I flew in 2004, observing for 8.5 days. BESS-Polar II flew in 2007-2008, observing for 24.5 days. No antihelium candidate was found in BESS-Polar I data among 8.4×10(6) |Z|=2 nuclei from 1.0 to 20 GV or in BESS-Polar II data among 4.0×10(7) |Z|=2 nuclei from 1.0 to 14 GV. Assuming antihelium to have the same spectral shape as helium, a 95% confidence upper limit to the possible abundance of antihelium relative to helium of 6.9×10(-8)} was determined combining all BESS data, including the two BESS-Polar flights. With no assumed antihelium spectrum and a weighted average of the lowest antihelium efficiencies for each flight, an upper limit of 1.0×10(-7) from 1.6 to 14 GV was determined for the combined BESS-Polar data. Under both antihelium spectral assumptions, these are the lowest limits obtained to date.