Let $G$ be a connected, simply-connected complex semisimple group. We have the famous Springer resolution $$T^\*(G/B)\rightarrow\mathcal{N}$$ of the closure of the regular nilpotent orbit. My understanding is that the closures of nilpotent $G$-orbits $\mathcal{O}$ admit symplectic resolutions $$T^\*(G/P)\rightarrow\overline{\mathcal{O}}$$ when $G=SL\_n(\mathbb{C})$, but that this need not be the case for other $G$. Accordingly, I am looking for a reference giving some information as to which nilpotent orbits have their closures resolved in this way. 



Which nilpotent orbit closures admit Springer resolutions?
This is answered (except for a few cases in $E\_7$ and $E\_8$) in: 
Baohua Fu, [Symplectic Resolutions for Nilpotent Orbits](http://arxiv.org/abs/math/0205048).


Maybe it's worth mentioning: orbits which are the image of $T^\*(G/P)$ for some $P$ are called **Richardson** and are relatively easy to understand. The tricky part is know when that map is a resolution, since in many cases (outside type A) it is finite to 1 instead. One useful criterion is that it will be a resolution it the orbit is simply connected.


