A New Limit on the Flux of Cosmic Antihelium

Authors :: Saeki, T.
Anraku, K.
Orito, S.
Ormes, J.
Imori, M.
Kimbell, B.
Makida, Y.
Matsumoto, H.
Matsunaga, H.
Mitchell, J.
Motoki, M.
Nishimura, J.
Nozaki, M.
Otoba, M.
Sanuki, T.
Streitmatter, R.
Suzuki, J.
Tanaka, K.
Ueda, I.
Yajima, N.
Yamagami, T.
Yamamoto, A.
Yoshida, T.
Yoshimura, K.
Saeki, T.
Anraku, K.
Orito, S.
Ormes, J.
Imori, M.
Kimbell, B.
Makida, Y.
Matsumoto, H.
Matsunaga, H.
Mitchell, J.
Motoki, M.
Nishimura, J.
Nozaki, M.
Otoba, M.
Sanuki, T.
Streitmatter, R.
Suzuki, J.
Tanaka, K.
Ueda, I.
Yajima, N.
Yamagami, T.
Yamamoto, A.
Yoshida, T.
Yoshimura, K.
Publication Year :: 1997
Abstract: A very sensitive search for cosmic-ray antihelium was performed using data obtained from three scientific flights of BESS magnetic rigidity spectrometer. We have not observed any antihelium; this places a model-independent upper limit (95 % C.L.) on the antihelium flux of 6*10**(-4) m**(-2)sr**(-1)s**(-1) at the top of the atmosphere in the rigidity region 1 to 16 GV, after correcting for the estimated interaction loss of antihelium in the air and in the instrument. The corresponding upper limit on the Hebar/He flux ratio is 3.1*10**(-6), 30 times more stringent than the limits obtained in similar rigidity regions with magnetic spectrometers previous to BESS.<br />Comment: REVTeX, 4 pages (including 5 EPS figures). Submitted to PRL