  We employ an accurate, ab initio potential energy surface (PES) which
describes the electronic interaction energy between the molecular anion OH$^-$
($^1\Sigma^+$) and the neutral rubidium atom Rb ($^2S$), to evaluate the
elastic and inelastic cross sections over a range of energies representative of
the conditions of low-T experiments in MOT traps, when combined with
laser-cooled rubidium gas. The system is considered to be in its vibrational
ground state, while the first four rotational levels are taken to be involved
in the cooling and heating collisional processes that are computed here. The
corresponding cooling and heating rates up to about 35 K are obtained from the
calculations and compared with the recent results in a similar experiments,
where He was the partner atom of the current anion.
