  A Kaluza-Klein model, with a matter source associated with Hawking radiation
from an evaporating black hole, is used to obtain a simple form for the radion
effective potential. The environmental effect generally causes a matter-induced
shift of the radion vacuum, resulting in the formation of a radion cloud around
the hole. There is an albedo due to the radion cloud, with an energy dependent
reflection coefficient that depends upon the size of the extra dimensions and
the temperature of the hole.
