The neutron target of the GELINA time-of-flight facility has been simulated with coupled electron-photon-neutron MCNP4C3 calculations. The main goal is to investigate the feasibility for the reduction of the neutron time spread without significantly compromising the neutron yield. An implementation of new photonuclear libraries into the Monte Carlo calculations was necessary to simulate the neutronics problem accurately. Absolute flux calculations were performed for both moderated and direct neutron spectra in order to validate the geometry model and the method used to deal with the neutronics problem. These results were compared with the measured neutron spectra at specific flight paths; an agreement within 20% was achieved. The resolution functions of the moderated spectrum currently in use were compared with our Monte Carlo simulations; here an excellent agreement was reached. Finally, the simulated resolution functions for the direct neutron spectrum were calculated with and without the presence of the moderator. This comparison illustrates the negative influence of the moderator on the resolution function for the fast neutron spectrum.