Initiation of nuclear reactions under laser irradiation of Au nanoparticles in the presence of thorium aqua-ions

摘要

Initiation of nuclear reactions in Thorium nuclei is experimentally studied under laser exposure of Au nanoparticles suspended in the aqueous solution of Th(NO_3)_4 (~(232)Th). The solutions are analyzed using either Atomic Absorption Spectrometry (AAS) or, gamma-spectrometry in the range of gamma-photons energy from 0.06 to 1.5 MeV. Real-time acquisition of gamma-spectra of the probes is achieved using a portable scintillator y-spectrometer. It is found that the reaction pathway depends on in which water, either. H_2O or D_2O, the laser exposure is carried out. Laser exposure at peak intensity of 10~(13) W/cm~2 in D_2O results in the decrease of probes activity of all elements of Th branching including that of ~(137)Cs impurity. Exposure in H_2O leads to the increase of activity of elements of Th branching as well as the one of the ~(137)Cs impurity due to fission of Th nuclei. Saturation of the liquids (H_2O or D_2O) with gaseous H_2 or D_2, respectively, enhances the nuclear reactions under laser exposure allowing their excitation at peak intensity as low as 10~(10) W/cm~2. Enhanced activity of the probe is observed after the end of laser exposure for several hours.