Reconstruction of 3D Electron-Positron Momentum Densities from 2D Projections: Role of Maximum-Entropy Deconvolution Prior to Reconstruction

The benefit of using a Maximum-Entropy deconvolution technique prior to reconstructing the three-dimensional momentum density from two-dimensional angular correlation of positron annihilation radiation (2DACAR) is highlighted. The technique is applied to experimental data for a single crystal of chromium in its paramagnetic phase. The resulting reconstructed momentum density features are significantly enhanced when the 2DACAR spectra are first deconvoluted, although there are artefacts present around p ∼ 0. It is also shown to agree well with the theoretical momentum density.