Abstract
Neutrons produced in nuclear interactions initiated by cosmic-ray muons present an irreducible background to many rare-event searches, even in detectors located deep underground. Models for the production of these neutrons have been tested against previous experimental data, but the extrapolation to deeper sites is not well understood. Here we report results from an analysis of cosmogenically produced neutrons at the Sudbury Neutrino Observatory. A specific set of observables are presented, which can be used to benchmark the validity of GEANT4 physics models. In addition, the cosmogenic neutron yield, in units of $10^{-4}\;\text{cm}^{2}/\left(\text{g}\cdot\mu\right)$, is measured to be $7.28 \pm 0.09\;\text{stat.} ^{+1.59}_{-1.12}\;\text{syst.}$ in pure heavy water and $7.30 \pm 0.07\;\text{stat.} ^{+1.40}_{-1.02}\;\text{syst.}$ in NaCl-loaded heavy water. These results provide unique insights into this potential background source for experiments at SNOLAB.
Highlights
High energy muons created in cosmic-ray interactions in the Earth’s atmosphere penetrate deep underground, where they induce electromagnetic and hadronic showers
The prerequisite deep-underground location of such experiments reduces the rate of spallation backgrounds, but even the small number of remaining events can prove limiting to the potential physics reach of the experiments
The average energy of the surviving cosmic muons increases with depth, and the extrapolation of cosmogenic neutron production rates from measurements made at shallow sites to greater depths is not well understood
Summary
High energy muons created in cosmic-ray interactions in the Earth’s atmosphere penetrate deep underground, where they induce electromagnetic and hadronic showers. These produce, among other particles of interest, free neutrons with an energy spectrum spanning several GeV. The SNO detector was a kiloton-scale heavy water detector, located at a depth of 5890 Æ 94 m.w.e. Using the parametrization found in [15], the average muon energy at this depth is ð363.0 Æ 1.2Þ GeV, higher than those in many other published studies [1,2,4,5,6,7,8,9,10,11,12,13,14], and comparable to that at LSD [3].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
