A semi-empirical four-parameter formula is proposed in order to systematize intermediate-and high-energy proton-induced spallation yields of target nuclei covering the 50-100 mass number interval. It is shown that the measured yields are reproduced by the formula with a degree of accuracy which is comparable with or better than those obtained in previous proton-spallation systematics by other authors. The formula predicts reliable values for the most probable mass number of isotopie distributions. In addition, it allows one to derive in a simple way the mean nominal number of nucléons lost by the struck target nucleus, the chargeand mass-yield distributions for the spallation residuals, the total spallation reaction cross section, and the N/Z charge-dispersion curves.

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A semi-empirical four-parameter formula is proposed in order to systematize intermediate-and high-energy photon-and electroninduced spallation cross sections of medium weight nuclei. Analytical expressions for the parameters are obtained from parameter-values calculated by best-fitting of experimental data. We extend the same treatment to bremsstrahlung-induced spallation yields, and we verify that very similar analytical expressions for the parameters are obtained. Such a four-parameter formula has shown to predict reliable values of unmeasured spallation reaction cross sections. The reproducibility of the experimental data by the present formula is comparable with or better than those by other semi-empirical formulae with a larger number of parameters.

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