ملخص: The stopping powers of polypropylene and mylar polymers for protons have been accurately measured over the energy intervals Ep=(0.352-3.009) MeV and Ep=(0.236-3.019) MeV, respectively.Ab initio calculations using the Sigmund-Schinner binary collision theory for electronic stopping yielded S(E) values fairly consistent with the measured data that show no noticeable deviations from the Bragg-Kleeman additivity rule. The data have also been analyzed in the framework of the modified Bethe-Bloch theory assuming additivity. Values of the mean excitation and ionization potential, I, and of the Barkas parameter, b, have been deduced for the two polymers and for their (C, O) atomic constituents by adopting values of these parameters recommended in the ICRU-49 report for the H element. Thus, the respective I-values {(56.90 +/- 0.72) eV, (79.92 +/- 1.30) eV} for the two polymers and the same b-value 1.39 for their (C, O) atomic constituents have been determined by adopting for H the value b=1.8, while the I-values {(81.73 +/- 1.38) eV, (109.46 +/- 6.55) eV} have been deduced for the (C, O) constituents by adopting for H the value I=19.2 eV. Priorily, the shell, Barkas and Bloch corrections to the calculated S(E) values have been evaluated for both polymers over the explored respective energy ranges. The obtained results are discussed in comparison with previous ones when reported in the literature to our knowledge.

لغة: إنجليزية