We present and test a new halo finder based on the spherical overdensity (SO)
method. This new adaptive spherical overdensity halo finder (ASOHF) is able to
identify dark matter haloes and their substructures (subhaloes) down to the
scales allowed by the analysed simulations. The code has been especially
designed for the adaptive mesh refinement cosmological codes, although it can
be used as a stand-alone halo finder for N-body codes. It has been optimised
for the purpose of building the merger tree of the haloes. In order to verify
the viability of this new tool, we have developed a set of bed tests that
allows us to estimate the performance of the finder. Finally, we apply the halo
finder to a cosmological simulation and compare the results obtained to those
given by other well known publicly available halo finders.Comment: Latex format, 16 pages, 11 postscript figures, accepted for
publication in Astronomy and Astrophysic