Measurements of isomeric cross sections for (n,2n) reaction on 140Ce, 142Nd and 144Sm isotopes around 14 MeV

The nuclear channel effect in the isomeric ratio of the reaction products

“…The simultaneous use of uranium and beryllium as photon-neutron converter provided a higher neutron flux than uranium converter. This uranium-beryllium converter was placed within a 120x120x120 cm 3 graphite cube, which served as a main neutron moderator to thermal and epithermal energy neutrons. The thermal neutron flux at the center of the cube was 4.10 8 neutrons/s.cm 2 at an electron energy of 25 MeV and a current of 20 μA.…”

“…The ratio of the yields of forming these states, the so called isomeric ratio IR has become a diverse source of information about nuclear structure and reaction mechanism. It has been used for studying reactions with photon, neutrons, proton [1][2][3][4], deuterium, tritium, alpha, heavy ions [5][6][7]; nuclear fission [8][9][10], or nucleon transfer, and complete and incomplete fusion reactions [11,12]. The IR is connected to different nuclear effects as the excitation energy, momentum transfer, spin dependence, nucleon configuration, intermediate state structure, nuclear channel effect, contributions of direct and preequilibrium processes and so on.…”