{"paper":{"title":"Search for Antihelium with the BESS-Polar Spectrometer","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.CO","authors_text":"A. Horikoshi, A. Itazaki, A. Kusumoto, A. Yamamoto, E.S. Seo, H. Fuke, J.F. Ormes, J. Nishimura, J. Suzuki, J.W. Mitchell, K. Abe, K.C. Kim, K. Matsumoto, K. Sakai, K. Takeuchi, K. Tanaka, K. Yoshimura, M. Hasegawa, M.H. Lee, M. Nozaki, M. Sasaki, N. Thakur, R.E. Streitmatter, R. Orito, R. Shinoda, S. Haino, S. Matsuda, T. Hams, T. Kumazawa, T. Yamagami, T. Yoshida, Y. Makida, Y. Matsukawa, Y. Shikaze, Y. Takasugi, Z. Myers","submitted_at":"2012-01-13T22:51:54Z","abstract_excerpt":"In two long-duration balloon flights over Antarctica, the BESS-Polar collaboration has searched for antihelium in the cosmic radiation with higher sensitivity than any reported investigation. 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\\times 10^6 |Z| = 2 nuclei from 1.0 to 20 GV or in BESS-Polar II data among 4.0\\times 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 of 6.9 \\times 10^"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1201.2967","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}