From the remaining two peaks in the bivariate histogram (Figure (C)), the peak corresponding to the lower X-ray graylevel values (~ 2.5 a.u.) was assigned to graphite since its database-derived linear X-ray attenuation coefficient is much smaller than that of Cu (Table ). Note that the drawn boxes in Figure (C) refer to the entire area of the 2D peak that was assigned to the segmented material. Finally, we assigned the remaining peak in the bivariate histogram at the neutron graylevel value of ~ 0.6 a.u., and an X-ray graylevel value of ~ 9 a.u. to the Cu CC.