Total cross-section

An empirical cross-section is used to produce the total cross-section data [,]: $\sigma$_c( Z,E ) = aE³+ b E²+ c E + d &sp;barn/atom

The values of the coefficients are stored in the DATA statement within the routine GRAYLI. For each element the fit was obtained over 27 experimental values of the total coherent cross-section. The accuracy of the fit is estimated to be about $\Delta \sigma /\sigma \approx 10$ , but it is better for most of the elements.