Study on charge states of 147Dy and 199Po produced in nuclear reactions of full fusion

Studies were made to obtain experimental data on ion charge distributions in the range of heavy nuclei, and also to elucidate the effect of excited states of nuclei on the value of ion charge. Investigated are disprosium and polonium charge distributions appearing after the evaporation of neutrons from excited compound nuclei which are the products of the 113Cd(40Ar, 6n)147Dy and 164Dy(40Ar, 5n)199Po reactions. Argon ion energy amounted to 198 MeV for 113Cd layer and 195 MeV for 164Dy layer. Charge states of recoil atoms were studied with the aid of a wide-range magnetic analyzer. It is found out that charge distributions of recoil atoms do not coincide with calculated ones, while the mean values of equilibrium charges are much greater than expected ones. An additional recharging of Dy and Po ions on a thin carbon foil (approximately 45 μg/cm2) in approximately 10-8 s after the escape from the target has led to charge distributions of these ions, which is in a satisfactory agreement with calculated values. Such a difference in charge distributions is explained by the presence of strongly converted transitions in Dy and Po nuclei with the formation of vacancies on internal electron shells of atoms, the filling of which leads to the growth of charges of flying Dy and Po ions. A possibility of the formation of such vacancies due to atomic transitions is discussed