**Introduction**

The SigmaCalc software has been developed in order to provide the IBA scientist with a tool for computing the differential cross sections required for an analytical work. Reliability of the calculated cross sections was proved by comparisons with posterior measurements and benchmark experiments. SigmaCalc is based on the already published and some new results of the data evaluation. Different theoretical models (optical, S- and R-matrix) with optimized parameters are used for calculations. No expertise in nuclear physics is needed in order to perform the calculations of the required cross sections with SigmaCalc.

A theoretical evaluation of the cross sections grounded on appropriate physics seems to be the only way to resolve the problem of nuclear data for IBA. Though experiments undertaken to determine the required cross sections are often reported and a lot of data are accumulated in data bases, all these cross sections should be evaluated prior to their widespread use. The reasons are as follows. The analysis of the available experimental information revealed numerous discrepancies in the reported cross sections values which are far beyond quoted experimental errors. In addition, due to cross sections dependence on a scattering angle the available data are valid only in the case of a scattering geometry very close to the geometry used in cross sections measurements. It was shown in numerous papers that the evaluation of the cross sections by combining a large number of different data sets in the framework of the theoretical model makes it possible to calculate excitation functions for analytical purposes for any scattering angle, with reliability exceeding that of any individual measurement.