Excitation of 73 eV (1/2+) isomeric level of U235 nuclei with electron impact

The calculation of cross sections of the anticonversion process is carried out in which the electron from the continuum state accomplishes E3-transition into the connected orbit exciting E3-transition of the U235 nucleus into the 73 eV isomeric level. The calculations of the partial cross sections are conducted for the neutral atom and uranium ion with charge Q=6 in the final state. Along with the process of anticonversion, the process of electron elastic scattering with excitation of the nuclear E3-transition is considered as well. Specific numerical solutions were carried out for the interval of the electron kinetic energy of 0 <= mv2/2 <1 keV, characteristic to the plasma with temperatures of T <= 100 eV. The obtained cross sections are used to estimate the population rate of the uranium isomeric level, dipped into plasma, where Ne is electron density and T is electron temperature. It is shown that the process of electron inelastic scattering leads to the population rate of the uranium nuclear isomeric level, exceeding that of during anticonversion in the system with the charge of Q=6 and futhermore in the neutral system (Q=0) by two orders. Consequently, the relative yield of the uranium isomer is determined by the product of Δt plasma confinment time and Ne xi (ee';T) isomer population rate in the (ee')-process. From the obtained (with an accuracy of approximately 1%) cross section of the (ee') electron scattering in the (U)+1+e system a rather simple estimation formular providing an accuracy of approximately 10% is obtained for the isomer population rate. For a plasma at T=73 eV with the density of Ne=1018 cm-3 (E=73 eV) this formular provides the population rate value of Nexxi approximately equal to 1.7x10-9 s-1