Non-negative crystalline and Poisson measures in the Euclidean space

We study properties of temperate non-negative purely atomic measures in the Euclidean space such that the distributional Fourier transform of these measures are pure point ones. A connection between these measures and almost periodicity is shown, several forms of the uniqueness theorem are proved. We also obtain necessary and sufficient conditions for a measure with positive integer masses on the real line to correspond the zero set of an absolutely convergent Dirichlet series with bounded spectrum.