pack circles into a partial annulus

[Robin Becker]

I need to pack circles into a partial annulus ie part of a larger circle bounded 
by two radii and angles of  say 18 & 90. The region is described in polar coords 
as {(r,theta) | r0<=r<=r1 & theta0<=theta<=theta1}. The circles to be packed 
have three different radii, but all will fit singly into the region. The idea is 
that they should be as far apart as possible so as to minimize overlap and avoid 
crossing the region boundary.

Circle packing is hard so I'm thinking of using some kind of spring/repulsion 
model to do this.

Has anyone any ideas about how to do this?
-- 
Robin Becker