  We describe a hybrid vacuum system in which a single ion or a well defined
small number of trapped ions (in our case Ba$^+$ or Rb$^+$) can be immersed
into a cloud of ultracold neutral atoms (in our case Rb). This apparatus allows
for the study of collisions and interactions between atoms and ions in the
ultracold regime. Our setup is a combination of a Bose-Einstein condensation
(BEC) apparatus and a linear Paul trap. The main design feature of the
apparatus is to first separate the production locations for the ion and the
ultracold atoms and then to bring the two species together. This scheme has
advantages in terms of stability and available access to the region where the
atom-ion collision experiments are carried out. The ion and the atoms are
brought together using a moving 1-dimensional optical lattice transport which
vertically lifts the atomic sample over a distance of 30$\,$cm from its
production chamber into the center of the Paul trap in another chamber. We
present techniques to detect and control the relative position between the ion
and the atom cloud.
