INVESTIGATION OF (γ,n) REACTIONS IN THE CHANNEL OF MULTIPARTICLE PHOTODISINTEGRATION OF ¹²C AND ¹⁶O NUCLEI

The reactions 12С(γ,n)3Не2a and 16O(γ,n)3He3a is investigated by a method that employs a diffusion chamber placed in a magnetic field and irradiated by a beam of bremsstrahlung photons with an end-point energy of 150 MeV. In the excitation curve for the 2a system, a resonance is found, and this resonance identified as the ground state of the 8Be nucleus. The parameters of the γ-quantum and neutron are calculated, and the partial channels 12С(γ,n)3Не8Ве0 and 16O(γ,n)3Hea8Ве0 reactions are singled out. It is shown that these reactions proceed according a sequential-type scheme with the formation of one or several unresolved excited states of 11C and 15O nuclei at the first step. The total cross section of the reactions was determined and a similarity in their behavior was found for Eγ > 55 MeV. A jumplike change in the dependence of the kinetic energy of the neutron on Eγ in different energy intervals of the γ-quantum was observed.