Advice on graphics to design circle with density-shaded sectors

Hello,

I am looking for some general advice on which graphics package to use to 
make a figure demonstrating my experimental design.

I want to design a circle with 7 sectors inside.  Then I will want to 
shade the sectors depending on densities of observations in the 
sectors.  I will also want to draw horizontal lines at increments along 
the sectors to demonstrate different distances out to the end of the sector.

Given this sparse description, does anyone have advice on what package 
or functions to use in R?

Thanks for your help,
John