The variation of the percentage ash content of the
coal samples with (l/dp)ln(Io/1) as obtained by SET
technique using three single y-ray energy sources, 133Ba,
137Cs and 6~ are shown in Figs 2, 3 and 4,
respectively. Figure 5 shows the variation of the
percentage ash content with In(lo/l)'/ln(lo/l)" as obtained
by DET technique using the dual y-ray energy source
133Ba (0.081 MeV)+22Na (1.274 MeV). The root mean
square error (r.m.s), the correlation coefficient (R), and
the regression equation, obtained using a suitable
regression technique are shown in Table 2