  As neutrinoless double-beta decay experiments become more sensitive and
intrinsic radioactivity in detector materials is reduced, previously minor
contributions to the background must be understood and eliminated. With this in
mind, cosmogenic backgrounds have been studied with the EXO-200 experiment.
Using the EXO-200 TPC, the muon flux (through a flat horizontal surface)
underground at the Waste Isolation Pilot Plant (WIPP) has been measured to be
{\Phi} = 4.07 $\pm$ 0.14 (sys) $\pm$ 0.03 (stat) $\times$ $10^{-7}$cm$^{-2}$
s$^{-1}$, with a vertical intensity of $I_{v}$ = 2.97$^{+0.14}_{-0.13}$ (sys)
$\pm$ 0.02 (stat) $\times$ $10^{-7}$cm$^{-2}$ s$^{-1}$ sr$^{-1}$. Simulations
of muon-induced backgrounds identified several potential cosmogenic
radionuclides, though only 137Xe is a significant background for the 136Xe
0{\nu}{\beta}{\beta} search with EXO-200. Muon-induced neutron backgrounds were
measured using {\gamma}-rays from neutron capture on the detector materials.
This provided a measurement of 137Xe yield, and a test of the accuracy of the
neutron production and transport simulations. The independently measured rates
of 136Xe neutron capture and of 137Xe decay agree within uncertainties. Geant4
and FLUKA simulations were performed to estimate neutron capture rates, and
these estimates agreed to within ~40% or better with measurements. The ability
to identify 136Xe(n,{\gamma}) events will allow for rejection of 137Xe
backgrounds in future 0{\nu}{\beta}{\beta} analyses.
