Study on isomer ratio in (n,2n) and (γ,n) reactions on 92Mo, 90Zr, 86Sr and 74Se

The method has been elaborated for calculating the isomer ratio in case of a small excitation energy of the residual nucleus and the isomer ratio has been measured in (n, 2n) and (γ, n) reactions on 92Mo, 98Zr, 06Sr and 74Se neutron deficient nuclei. A neutron generator with 1010 neutron/c yield served as a neutron source in the experiment. The energy of incident neutrons made up Esub(n)=14.5+-0.2 MeV. The experiment on the (γ, n) reaction was conducted in the microtron with the maximal bremsstrahlung energy Esub(γ)sup(max)=14.5 MeV. Isomeric ratio was determined by the activation method. γ-quanta of the reaction products were registered by a semiconducting detector and a multichannel analyzer. The good agreement between the experimental and calculation results on the (γ, n) reaction has confirmed that the characteristics of the residual nucleus, penetrability factors of the emitted neutrons, and etc. involved in the calculations are quite reliable. Study of the neutron (n, 2n) reaction has given values of the spin dependence parameter for the nuclear level density at excitation energies approximately 14 MeV