  A collision of Bose-Einstein condensates is a useful source of single
nonclassically correlated pairs of atoms. Here, we consider elastic scattering
of atoms from elongated clouds taking into account an effective, finite
duration of the collision due to the expansion of the condensates. Also, we
include the quasicondensate nature of the degenerate quantum gases, due to a
finite temperature of the system. We evaluate the pair correlation function
measured experimentally in K. V. Kheruntsyan, et. al. Phys. Rev. Lett. 108,
260401 (2012). We show that the finite duration of the collision is an
important factor determining the properties of the correlations. Our analytic
calculations are in agreement with the measurements. The analytical model we
provide, useful for identifying physical processes that influence the
correlations, is relevant for experiments with nonclassical pairs of atoms.
