Table of resonance integrals

The authors' purpose is to regroup the measured resonance integrals for a number of materials, after correcting them with a view to reducing them to a common definition, and to compare them with the value calculated from resonance parameters, when these parameters are known with a sufficient degree of accuracy. These comparisons are made for use with the infinite dilution method. The resonance integral above the 1/V part, which corresponds to infinite dilution, is defined by the relationship: I = ∫Ec∞[σ(E) - σo√E/E0] dE/E. From this we derive the total integral Ir by selecting the lower limit of integration Ec equal to 0.55 eV. Only those materials are studied whose lowest resonance wing is extinguished at this energy. The resonance integrals calculated from the parameters are determined for infinite dilution by means of the ZUT computation programme and the complementary TUZ programme for the contribution of unresolved resonances. The authors have made certain corrections in the measured resonance integrals to standardize and thereby facilitate comparisons. These consisted, in particular, of the following: calculation of the 1/V part to obtain I from Ir; modification of quenching to reduce them to energy Ec = 0.55 eV; standardization relative to the resonance integral for gold, taken as equal to I = 1540 b and to the cross-section at 2200 m/s of natural boron, taken as equal to 761 b or 771 b, depending on the isotopic concentrations; extrapolation to infinite dilution; adoption, if necessary, of the final thermal cross-sections when they enter into the calculation of I. For each material the authors mention all the measurements with which they are acquainted, the calculated value and the recommended values for I and Ir that can be deduced from this compilation. (author)