Study on the Three‐Dimensional Electron Momentum Density and the Fermi Surface in Cu by Positron Annihilation

The electron momentum density and the Fermi surface in Cu are studied by a two‐dimensional angular correlation of positron annihilation radiation (2D‐ACAR). The three‐dimensional electron momentum density is reconstructed using the image reconstruction technique. The electron momentum density obtained in the extended zone scheme is reduced to that in the reduced zone scheme by using the Lock‐Crisp‐West (LCW) folding procedure. The Fermi surface in Cu is determined in the reduced zone scheme. The enhancement parameters and the autocorrelation function are compared with the theoretical calculations.