  One of the main goals of the Long Baseline Neutrino Oscillation experiment
(LBNO) experiment is to study the L/E behaviour of the electron neutrino
appearance probability in order to determine the unknown phase $\delta_{CP}$.
In the standard neutrino 3-flavour mixing paradigm, this parameter encapsulates
a possibility of a CP violation in the lepton sector that in turn could help
explain the matter-antimatter asymmetry in the universe. In LBNO, the
measurement of $\delta_{CP}$ would rely on the observation of the electron
appearance probability in a broad energy range covering the 1$^{st}$ and
2$^{nd}$ maxima of the oscillation probability. An optimization of the energy
spectrum of the neutrino beam is necessary to find the best coverage of the
neutrino energies of interest. This in general is a complex task that requires
exploring a large parameter space describing hadron target and beamline
focusing elements. In this paper we will present a numerical approach of
finding a solution to this difficult optimization problem often encountered in
design of modern neutrino beamlines and we will show the improved LBNO
sensitivity to the presence of the leptonic CP violation attained after the
neutrino beam optimization.
