Use of the absolute parametric method to evaluate the analytical significance of threshold reactions on P, Si, Al and Mg by NAA

We investigated the use of threshold reactions on magnesium, aluminum, sili con and phosphorus to determine elemental concentrations and also to correc t analytical interferences, using the parametric method. The reactor neutro n spectrum averaged cross sections of the threshold reactions on these elem ents were referred to the (111+/-3) mb value for the Ni-58(n,p)Co58p+m reac tion cross section. The results of the cross section measurements are: Mg-2 5(n,p)Na-25, 1.57+/-0.12 mb; Si-28(n,p)Al-28, 5.68+/-0.25 mb; Si-29(n,p)Al- 29, 3.02+/-0.15 mb; Si-30(n,alpha)Mg-27, 0.1346+/-0.0090 mb; and P-31(n,alp ha)Al-28. 1.9 12+/-0.083 mb. The values for the cross sections of the follo wing reactions: Mg-24(n,p)Na-24 1.441+/-0.092 mb; Al-27(n,p)Mg-27, 3.84+/-0 .18 mb: and Al-27(n,alpha)Na-24 0.721+/-0.028 mb were re-measured to check the methodology. We present the application of these values to the analysis of some reference materials.