Study of secondary neutron interactions with ²³²Th, ¹²9I, and ¹²7I nuclei with the uranium assembly "QUINTA" at 2, 4, and 8 GeV deuteron beams of the JINR Nuclotron accelerator.

The natural uranium assembly, "QUINTA", was irradiated with 2, 4, and 8GeV deuterons. The (232)Th, (127)I, and (129)I samples have been exposed to secondary neutrons produced in the assembly at a 20-cm radial distance from the deuteron beam axis. The spectra of gamma rays emitted by the activated (232)Th, (127)I, and (129)I samples have been analyzed and several tens of product nuclei have been identified. For each of those products, neutron-induced reaction rates have been determined. The transmutation power for the (129)I samples is estimated. Experimental results were compared to those calculated with well-known stochastic and deterministic codes.

Determination of the cross section for nuclear reactions in complex nuclear decay chains.

In the present paper decays of genetically connected nuclei are considered and equations for their independent cross sections are derived. An optimisation parameter is proposed for an experiment where spectra of the residual nuclei are studied by the induced activity method. This parameter depends on irradiation time, delay time and spectrum measurement time.