What is the relation between Z & E in linear attenuation coefficient

with higher Z the energy of the penetrated particle or radiation would be decreased and hence the linear attenuation would be small range E as the energy is geeting high the more the linear coefficient increase (R) as R ∝ E.....
that is why the Gama radiation is in need for led to be stopped since its energy E is high, that give Gama the power to penetrate more ....