Neutrino-induced upward stopping muons in Super-Kamiokande

• Published in: Physics letters. B Vol. 467; no. 3; pp. 185 - 193
• Main Authors: Fukuda, Y., Ishihara, K., Itow, Y., Kajita, T., Kameda, J., Kasuga, S., Kobayashi, Y., Koshio, Y., Miura, M., Nakahata, M., Nakayama, S., Obayashi, Y., Okada, A., Okumura, K., Sakurai, N., Shiozawa, M., Suzuki, Y., Takeuchi, H., Takeuchi, Y., Totsuka, Y., Yamada, S., Earl, M., Habig, A., Messier, M.D., Scholberg, K., Sulak, L.R., Walter, C.W., Barszczak, T., Casper, D., Gajewski, W., Kropp, W.R., Price, L.R., Smy, M., Vagins, M.R., Keig, W.E., Ellsworth, R.W., Tasaka, S., Kibayashi, A., Learned, J.G., Stenger, V.J., Takemori, D., Ishii, T., Ishino, H., Nakamura, K., Oyama, Y., Sakuda, M., Sasaki, O., Echigo, S., Kohama, M., Suzuki, A.T., Inagaki, T., Nishikawa, K., Haines, T.J., Blaufuss, E., Sanford, R., Chen, M.L., Goodman, J.A., Sullivan, G.W., Hill, J., Jung, C.K., Martens, K., Mauger, C., McGrew, C., Sharkey, E., Viren, B., Yanagisawa, C., Inaba, S., Okazawa, H., Saji, C., Takahashi, M., Takahata, M., Higuchi, K., Nagashima, Y., Takita, M., Yamaguchi, T., Yoshida, M., Kim, S.B., Etoh, M., Hasegawa, A., Hatakeyama, S., Iwamoto, T., Koga, M., Maruyama, T., Ogawa, H., Suzuki, A., Tsushima, F., Koshiba, M., Hatakeyama, Y., Koike, M., Nemoto, M., Nishijima, K., Fujiyasu, H., Futagami, T., Hayato, Y., Kanaya, Y., Kaneyuki, K., Watanabe, Y., Kielczewska, D., Stachyra, A.L., Young, K.K.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1999
• Subjects: Atmospheric muon neutrinos; Cosmic rays; Neutrino oscillations; Super-Kamiokande; Upward stopping muons; Upward throughgoing muons; Upward throughgoing muons; Upward stopping muons; Neutrino oscillations; 14.60.Pq; 96.40.Tv; Super-Kamiokande; Atmospheric muon neutrinos; Cosmic rays
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/S0370-2693(99)01188-0

A total of 137 upward stopping muons of minimum energy 1.6 GeV are observed by Super-Kamiokande during 516 detector live days. The measured muon flux is
0.39±0.04
(stat.)±0.02
(syst.)×10
−13
cm
−2s
−1sr
−1
compared to an expected flux of
0.73±0.16
(theo.)×10
−13
cm
−2s
−1sr
−1
. Using our previously-published measurement of the upward through-going muon flux, we calculate the stopping/through-going flux ratio
R
, which has less theoretical uncertainty. The measured value of
R=0.22±0.02
(stat.)±0.01
(syst.)
is significantly smaller than the value 0.37
+0.05
−0.04(theo.) expected using the best theoretical information (the probability that the measured
R
is a statistical fluctuation below the expected value is 0.39%). A simultaneous fitting to zenith angle distributions of upward stopping and through-going muons gives a result which is consistent with the hypothesis of neutrino oscillations with the parameters sin
22
θ>0.7 and 1.5×10
−3<
Δm
2<1.5×10
−2 eV
2 at 90% confidence level, providing a confirmation of the observation of neutrino oscillations by Super-Kamiokande using the contained atmospheric neutrino events.