Research of Interaction Processes of Fast and Thermal Neutrons with Solution of Organic Dye Methyl Orange

Abstract

The emergence of powerful sources of ionizing radiation, the needs of nuclear energy, technology and medicine, as well as the need to develop reliable methods of protection against the harmful effects of penetrating radiation stimulated the development of such branches of science as radiation chemistry, radiation biology, radiation medicine. When an organic dye solution is exposed to ionizing radiation, it irreversibly changes color. As a result, the absorbed dose can be determined. The processes of interaction of neutron fluxes with an aqueous solution of an organic dye methyl orange (МО) – C14H14N3О3SNa, containing and not containing 4% boric acid, have been investigated. The work was carried out on a LINAC LUE-300 at NSC KIPT. A set of tungsten plates was used as a neutron-generating target. The electron energy was 15 MeV, the average current was 20 μA. The samples were located behind the lead shield and without it, with and without a moderator. Using the GEANT4 toolkit code for this experiment, neutron fluxes and their energy spectra were calculated at the location of experimental samples without a moderator and with a moderator of different thickness (1-5 cm). An analysis of the experimental results showed that when objects without lead shielding and without a moderator are irradiated, the dye molecules are completely destroyed. In the presence of lead protection, 10% destruction of the dye molecules was observed. When a five-centimeter polyethylene moderator was installed behind the lead shield, the destruction of dye molecules without boric acid on thermal neutrons was practically not observed. When the fluxes of thermal and epithermal neutrons interacted with a dye solution containing 4% boric acid, 30% destruction of dye molecules was observed due to the exothermic reaction 10B (n, α). The research has shown that solutions of organic dyes are a good material for creating detectors for recording fluxes of thermal and epithermal neutrons. Such detectors can be used for radioecological monitoring of the environment, in nuclear power engineering and nuclear medicine, and in the field of neutron capture therapy research in particular.

Development and Testing of a System for Forming Neutron Fluxes on a Linear Electron Accelerator

“…5 that when the samples studied without a reflector are irradiated with a neutron flux, the absorption spectrum of an aqueous solution of the methyl orange dye "sags" by 25 percent relative to the non-irradiated solution. This indicates a 25% breakdown of dye molecules in solution due to the interaction of thermal and epithermal neutron fluxes with 10 В, which is contained in boric acid [4]. When cementgraphite reflectors were used in the experiment, an additional 15% breakdown of dye molecules was observed due to an increase in the neutron flux density.…”

“…Test tubes with an aqueous solution of the organic dye methyl orange with the addition of 4% boric acid [4], which were installed inside the lead protection, were used as detectors of the formed neutron fluxes. The scheme of the experiment is shown in Fig.…”

Investigation of Interaction Mechanisms of High Energy Electrons and Gamma Quantum with Aqueous Solution of Methyl Orange Dye

“…The experimental part of the work was carried out on the LINAC LUE-300 NSC KIPT [12,17]. The target was an aqueous solution of methyl orange dye with a volume of 1 cm 3 .…”

“…A tungsten converter, when irradiated with an electron beam, is also a source of neutrons. However, the contribution of neutrons to the change in the color of the dye solution does not exceed ten percent [12]. Since the destruction of methyl orange molecules under the action of a neutron flux on it is insignificant, this contribution was not taken into account in the work.…”

“…Thus, the interest of medical science in such research becomes obvious. For medicine in general and for radiation therapy in particular, organic dyes can be a good research material [12]. This is not a complete list of problems that can be solved by the research that we are conducting in the framework of this work.…”