particles / collision / deflectors ?

hi everybody,
I’m looking after the deflectors in blender?
Can somebody tell me how to manage particles collisions with objects?
Does it need a plugin? Is there any tutorial about this?

I didn’t find yet any answers in this forum.

Many thx in advance,

particles don’t care about other objects

but you can control their flow within a lattice. (it is in the blender 2.0 guide, cept there it is dupli object, same idea)