Two dimensional Fourier transformed angular correlation of annihilation radiation (2D-FT-ACAR) spectra have been taken for 10(19) cm(-3) Phosphorus-doped Si in the as grown state and after being subjected to 1.8 MeV e(-) fluences of 2x10(18) cm(-2). In the spectra of the irradiated samples, the zero-crossing points are observed to displace outwards from the Bravais lattice positions. It is suggested that this results from positrons annihilating with electrons in localized orbitals at the defect site. An attempt is made to extract just the component of the defect's positron-electron autocorrelation function that relates to the localized defect orbitals. It is argued that such an extracted real-space function may provide a suitable means for obtaining a mapping of localized defect orbitals.