1202.5000 (D. Barker et al.)

Muon-Induced Background Study for an Argon-Based Long Baseline Neutrino
Experiment    [PDF]

D. Barker, D. -M. Mei, C. Zhang

We evaluated rates of transversing muons, muon-induced fast neutrons, and
production of $^{40}$Cl and other cosmogenically produced nuclei that pose as
potential sources of background to the physics program proposed for an
argon-based long baseline neutrino experiment at the Sanford Underground
Research Facility (SURF). The Geant4 simulations were carried out with muons
and muon-induced neutrons for both 800 ft (0.712 km.w.e.) and 4850 ft levels
(4.3 km.w.e.). We developed analytic models to independently calculate the
$^{40}$Cl production using the measured muon fluxes at different levels of the
Homestake mine. The muon induced $^{40}$Cl production rates through stopped
muon capture and the muon-induced neutrons and protons via (n,p) and (p,n)
reactions were evaluated. We find that the Monte Carlo simulated production
rates of $^{40}$Cl agree well with the predictions from analytic models. A
depth-dependent parametrization was developed and benchmarked to the direct
analytic models.
We conclude that the muon-induced processes will result in large backgrounds
to the physics proposed for an argon-based long baseline neutrino experiment at
a depth of less than 4.0 km.w.e.

View original: http://arxiv.org/abs/1202.5000