  Recently, in analogy with multiphoton ionization, it has been suggested that
multiparticle ionization can also be induced by massive systems. We explore in
this paper the possibility that multiparticle absorption processes can also
take place for massive particles. To study it we consider, in a perturbative
way, a model of absorption which illustrates the analogies with Glauber's
scheme for photons and previous analysis on matter-waves coherence. A major
advantage of this approach is that the dependence of the absorption rates on
the wavefunction of the incident system can be analyzed in an explicit way. The
calculations confirm the form of the second order (two-particle) contributions.
