Fission of Heavy Elements Induced by Medium High Energy Protons
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چکیده
In this paper is presented a discussion of fission induced in heavy elements (uranium) by protons with kinetic energies below about 400 MeV with the main emphasis on fission with protons of a few hundred MeV energy *. Thus, reactions where meson interference becomes of any importance are not considered. Even if fission is the main reaction in heavy nuclei this can not be discussed without consideration of the cascade-evaporation process generally considered to take place at high energy interactions with complex nuclei. As described by the S E R B E R 1 model these reactions start with a fast nucleonic cascade (time scale ~ 10~2 2 sec) in the target nuclei knocking out neutrons and protons and leading to a varity of product nuclei — each with broad distribution of excitation energies — cascade residuals. The subsequent deexcitation of the cascade residuals takes place by successive evaporations of nucleons (time scale 1 0 2 0 sec), each with a few MeV of kinetic energy (in heavy targets mainly neutrons) and leaving behind a complex mixture of reaction products — spallation products. Both steps of this model have been treated by the Monte Carlo method 2 5 . The results of the calculations are in good agreement with the experimental data for the light particles knocked out and emitted in the two steps at energies of interest for the present study.
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تاریخ انتشار 2012