We analyze the influence of the extension of incoherent sources in one- and
two-particle double-slit gedanken interferometry of massive particles. For
one-particle systems, in the Gaussian-slit approximation, the intensity of
the oscillatory term is diminished by an exponential factor. This analytic
al form differs from that obtained in optics. For two-particle systems we o
btain simultaneously one- and two-particle interferences. We compare our ap
proach with other results previously presented in the literature suggesting
a type of complementarity between both types of interference patterns. (C)
2001 Elsevier Science B.V. All rights reserved.