Measurement of the Cosmic Ray and Neutrino-Induced Muon Flux at the Sudbury Neutrino Observatory

SNO Collaboration

doi:10.1103/PhysRevD.80.012001

paper

Measurement of the Cosmic Ray and Neutrino-Induced Muon Flux at the Sudbury Neutrino Observatory

arXiv:0902.2776 · doi:10.1103/PhysRevD.80.012001

Abstract

Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and un-oscillated portion of the neutrino flux. A total of 514 muon-like events are measured between $- 1 \leq cos θ_{zenith} \leq 0.4$ in a total exposure of 2.30\times 10^{14} $c m$ ^{2} $s . T h e m e a s u r e df l ux n or ma l i z a t i o ni s$ 1.22 \pm 0.09 $t im es t h e B a r t o l t h r ee - d im e n s i o na l f l ux p r e d i c t i o n . T hi s i s t h e f i r s t m e a s u r e m e n t o f t h e n e u t r in o - in d u ce df l ux w h er e n e u t r in oosc i l l a t i o n s a r e minimi z e d . T h ez e ni t h d i s t r ib u t i o ni sco n s i s t e n tw i t h p r e v i o u s l y m e a s u r e d a t m os p h er i c n e u t r in oosc i l l a t i o n p a r am e t er s . T h ecos mi cr a y m u o n f l ux a tS N O w i t h z e ni t han g l e$ \cosθ_{\rm zenith} > 0.4 $i s m e a s u r e d t o b e$ (3.31 \pm 0.01 {\rm (stat.)} \pm 0.09 {\rm (sys.)}) \times 10^{-10}~μ $/ s / c m$ ^{2}$.

17 pages, 11 figures