Table 2. Mass attenuation coefficients of 60 and 662 KeV gamma photons
 for those chemical elements frequently found in soils (Hubbell,
 49).
 Mass Attenuation Coefficient, /j
 (cm2/g)
 Element 60 KeV 662 KeV

 H 0.326 0.1538
 B 0.158 0.0716
 C 0.179 0.0774
 N 0.181 0.0774
 0 0.190 0.0775
 F 0.191 0.0735
 Na 0.227 0.0741
 Mg 0.257 0.0765
 Al 0.277 0.0748
 Si 0.219 0.0772
 P 0.347 0.0750
 S 0.404 0.0775
 Cl 0.434 0.0745
 K 0.557 0.0756
 Ca 0.646 0.0778
 Ti 0.752 0.0716
 V 0.829 0.0706
 Cr 0.971 0.0723
 Mn 1.07 0.0714
 Fe 1.20 0.0732
 Co 1.33 0.0722
 Ni 1.52 0.0754


 values of riass attenuation coefficients for the absorber materials were
 calculated using equation [13]. The results of that comparison are pre-
 sented in Table 3, and a plot of values of theoretical (g,) versus ex-
 perimental (1kE) mass attenuation coefficients for the soils and other
 absorber materials is presented in Figure 5. Theoretical and experimen-
 tal values were closely correlated and were easily fitted by linear regres-
 sion to the straight line

 E = 0.0119 + 0.9573 I'T. [14]

 Note that most of the experimental values are lower than the theoretical
 ones, and this is due to experimental difficulties which will be discussed
 in another section. The correlation coefficient for the Least-Squares fit
 of equation [14] to the data was r = 0.994. Thus Ferraz (26) con-
 cluded that equation [13] is a valid means for estimating the mass at-
 tenuation coefficient for water and soils of the type used to generate the
 data in Table 3.