Atmospheric Muon Neutrino Fraction above 1 GeV

R. Clark; R. Becker-Szendy; C. B. Bratton; J. Breault; D. Casper; S. T. Dye; W. Gajewski; M. Goldhaber; T. J. Haines; P. G. Halverson; D. Kielczewska; W. R. Kropp; J. G. Learned; J. LoSecco; C. McGrew; S. Matsuno; R. S. Miller; L. Price; F. Reines; J. Schultz; H. W. Sobel; J. Stone; L. R. Sulak; R. Svoboda; M. Vagins

doi:10.1103/PhysRevLett.79.345

Atmospheric Muon Neutrino Fraction above 1 GeV

R. Clark, R. Becker-Szendy, C. B. Bratton, J. Breault, D. Casper, S. T. Dye, W. Gajewski, M. Goldhaber, T. J. Haines, P. G. Halverson, D. Kielczewska, W. R. Kropp, J. G. Learned, J. LoSecco, C. McGrew, S. Matsuno, R. S. Miller, L. Price, F. Reines, J. Schultz, H. W. Sobel, J. Stone, L. R. Sulak, R. Svoboda, and M. Vagins

Phys. Rev. Lett. 79, 345 – Published 21 July 1997; Erratum Phys. Rev. Lett. 79, 2754 (1997)

Abstract

A 2.1 kton yr exposure of data from the Irvine-Michigan-Brookhaven detector has yielded 72 atmospheric neutrino events with a vertex contained inside the fiducial volume and at least 0.95 GeV of visible Čerenkov energy. The ratio of these two ratios $(\frac{muon l i ke}{tota l})_{Data} / (\frac{muon l i ke}{tota l})_{MC}$ was found to be ${1.1}_{- 0.12}^{+ 0.07} (stat) \pm 0.11 (syst)$ . The zenith angle dependence of this ratio of ratios is consistent with being flat. The region of ${sin}^{2} (2 θ) > 0.5$ and $δ m^{2} > 9.8 \times 10^{- 3} {eV}^{2}$ has been excluded to the 90% confidence level for $ν_{μ} \to ν_{e}$ oscillations while the region of ${sin}^{2} (2 θ) > 0.7$ and $δ m^{2} > 1.5 \times 10^{- 2} {eV}^{2}$ has been excluded to the 90% confidence level for $ν_{μ} \to ν_{τ}$ oscillations.