2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/18893Electron-positron momentum densities in Y, reconstructed from two-dimensional angular correlation of annihilation radiation spectra, are compared with the theoretical predictions of fully-relativistic augmented plane-wave calculations. Knowledge of the theoretical densities and of the effects on them of certain symmetry selection rules has allowed us to separate two hole Fermi sur-faces in the third and fourth bands and to establish some Fermi momenta for each of them.Materials Sciencetext