  In this work, we study crystalline electric field effects in the heavy
fermion superconductor CeIrIn5. We observe two regions of broad magnetic
response in the inelastic neutron scattering spectra at 10 K. The first
corresponds to the transition between the gamma7 groundstate doublet and the
first excited state doublet at 4 meV interwoven with a broad quasielastic
contribution. The second region corresponds to the transition between the
ground state and the second excited state doublet at 28 meV. The large
Lorentzian half-widths of the peaks (~10 meV) calls into question calculations
for the specific heat and magnetic susceptibility that assume sharp crystal
field levels. Consequently, we have calculated the inelastic neutron scattering
spectra and magnetic susceptibility using the Anderson impurity model within
the non-crossing approximation (NCA) including the effects of crystal field
level splitting.
