  Ultra-relativistic Au+Au collisions at RHIC ($\sqrt{s}$=130, 200 GeV) are
used to study production of rare anti-nuclei. These clusters of anti-nucleons
are formed by coalescence, i.e. overlapping wave functions of anti-nucleons.
The coalescence coefficients $B_2$ for Anti-$d$ and $B_3$ for Anti-$^3He$ are
determined, and used to derive the fireball radius.
