Brief annotation and scientific rationale:
Information about neutron-nuclear interactions is extremely important for both fundamental and applied physics. The fact that the neutron has no electric charge makes it a unique probe for studying nuclear forces. Due to electrical neutrality, the high penetrating power of neutron radiation makes it promising for studying the structure of matter at both the nuclear and molecular levels. Neutrons are also widely used for applied purposes: in inspection systems, non-destructive elemental analysis facilities, in instruments for studying the immediate environment of boreholes (logging), as well as in the creation of neutron and gamma radiation detectors used on board orbital and descent spacecraft for analysis of soil and atmosphere of celestial bodies. Information about neutron-nuclear reactions is also necessary for the design of promising nuclear power facilities, as well as for modeling various devices and objects that interact with neutron radiation in one way or another. An indicator of the relevance of studying the characteristics of neutron-nuclear interactions can be the fact that the list of the most requested nuclear data for the most part consists of queries directly related to neutron-nuclear reactions.

The TANGRA (TAgged Neutrons and Gamma Rays) project is aimed at studying neutron-nuclear reactions using the tagged neutron method, finding new ways to use neutron methods in fundamental and applied research, improving existing and creating new approaches to processing the results of nuclear physics experiments. One of the tasks to be solved within the framework of the project is the interpretation of existing experimental data on the reactions of interaction of fast neutrons with atomic nuclei, their systematization and validation. The priority area of work is the acquisition of nuclear data.

Expected results upon completion of the project:
Performing experiments to study the angular distributions of scattered neutrons.

Experimental study of (n,γ) and (n’,γ)-correlations.

Theoretical description of the studied reactions.

Conducting experiments to study the reaction (n,2n).

Conclusion on the applicability of the tagged neutron method for elemental analysis of soils. In case of a positive result, the creation of prototypes of stationary and mobile facilities, as well as methodological recommendations for their use for agricultural and environmental monitoring.

Expected results of the project in the current year:
Measurements of angular correlations and cross sections for characteristic gamma-lines emitted by fast neutron reaction products using high-resolution γ-ray detectors.

Preparation of an experiment to study the (n,2n) reaction.

Development of a theoretical description of angular distributions of gamma-rays emitted during deexcitation of products of reactions with fast neutrons.

Field tests of a mobile facility for determining the carbon content in soil.

Brief annotation and scientific rationale:
The project is aimed at modernizing the main systems of the electrostatic charged particle accelerator EG-5, developing ion-beam and complementary methods for studying the elemental composition and physical properties of near-surface layers of solids.

Goals of the project: to provide technical feasibility for the implementation of the scientific program of the JINR Topical Plan in studying reactions with fast quasi-monoenergetic neutrons; development of nuclear physics methods for studying the elemental composition; solution of problems of neutron-radiation materials science; implementation of practical applications of neutron physics; ensuring technical feasibility for the implementation of the unique options of the microbeam spectrometer.

Objectives of the project. The main technical task of the project is to restore the energy range of accelerated particles of 900 keV - 4.1 MeV and increase the ion beam current to 100-250 μA while maintaining the energy stability of the ion beam at a level no worse than 15 eV, ensuring the spatial stability of the ion beam, sufficient to implement the option of the microbeam spectrometer / nuclear microprobe.

The main organizational task is the formation and development of human resources potential to ensure the full implementation of the project for at least 3 seven-year periods.

The objectives of the project also include the upgrade of the experimental infrastructure of the accelerator complex, in particular, the development of new methods for studying the physical properties of the surface of materials that can complement and improve the quality of the obtained scientific results, the intensification of international scientific and technical cooperation, the organization of user policy, the formation of an interlaboratory accelerator center on the basis of FLNP JINR to solve a wide range of unique scientific and technological problems.

The main criteria for the successful implementation of the project are providing a neutron flux sufficient to conduct nuclear physics experiments with fast neutrons, and an energy stability of the ion beam sufficient to create a microbeam spectrometer/nuclear microprobe.

Expected results upon completion of the project:
As a result of the implementation of the project, the technical parameters of the accelerator will be restored (energy of accelerated particles of 4.1 MeV at a maximum current of at least 100 μA), which will make it possible to conduct studies of reactions with fast neutrons at JINR, as well as provide technical conditions for the installation of a microbeam spectrometer. A neutron generator based on a solid-state lithium target with a moderator will be added to the existing neutron generator with a gas target, and the chamber for irradiating samples with ion beams will be modified.

A new specialized laboratory will be created for the preparation of objects of study, which will be equipped with complementary methods for studying the optical and electronic properties of the surface, such as ellipsometry, optical and electron microscopy, methods for studying electrical properties at direct and alternating current (voltammetry, impedancemetry).

In addition to modernization and expansion of the instrumental base of the accelerator complex, the formation of personnel potential for the next 20-30 years will be carried out. The available methods of elemental analysis will be supplemented by methods of analysis based on prompt gamma rays from inelastic neutron scattering and neutron activation analysis.

Modernization of EG-5 at JINR, where there are highly qualified specialists, good detecting equipment and valuable developments in the field of neutron investigations of atomic nuclei, will make it possible in the short term to conduct a number of new, unique experiments on obtaining the energy spectra and angular distributions of charged particles from (n, α) and (n, p) / (α, n) and (p, n) reactions and integral and differential cross sections of the latter in the neutron energy range up to ~6 MeV, on processes of fission of atomic nuclei by fast neutrons, activation analysis, experiments in the field of neutron materials science and etc.

Expected results of the project in the current year:
Certification and commissioning of the EG-5 accelerator and its experimental halls.

Replacement of the selsyn control system with an optoelectronic analogue.

Modernization of the radiation monitoring and personnel protection system.

Modernization of the ion beam spectrometer complex.

Commissioning of a solid-state lithium neutron-producing target.

Automation of accelerator service systems. 

Implementation of technical projects, in particular, the project with JSC Mikron (Zelenograd) “Ion-beam processing of semiconductor wafers with a diameter of 150 mm in a quantity of up to 200 pcs.”, the project to study the radiation resistance of polymer materials for the cooling system of detectors for the NICA collider, the project “Study of the dependence of sensitivity of the UDKN-04R device on neutron energy” in cooperation with JSC SNNIP (SC ROSATOM, Moscow).

Brief annotation and scientific rationale:
Nuclear processes and structural changes in materials induced by slow, resonance and fast neutrons and accelerated charged particles are traditionally in the focus of research attention at FLNP JINR. The interaction of neutrons with atomic nuclei is of interest for both fundamental and applied research.

The integrated use of the FLNP basic facilities (IREN pulsed source of resonance neutrons, IBR-2 pulsed reactor, EG-5 electrostatic generator) makes it possible to conduct nuclear physics research in a wide range of neutron energies from cold neutrons to ~20 MeV, and the use of external neutron sources, such as the n_TOF neutron time-of-flight facility at CERN, allows expanding the energy range to several hundreds of MeV. Fundamental research carried out at the FLNP Department of Nuclear Physics includes studies on the violation of space and time symmetry, the mechanism of nuclear reactions, the structure of atomic nuclei, fission processes induced by neutrons, neutron-induced reactions with the emission of light particles, the properties of the neutron as an elementary particle, the properties of ultracold and very cold neutrons, quantum mechanical effects involving neutrons.

Also, in FLNP, a variety of research programs has been developed for applied investigations, such as obtaining nuclear data and information on the radiation resistance of materials for nuclear technologies, power engineering and transmutation, radiation mutagenesis on fast neutrons, neutron activation analysis using thermal and epithermal neutrons, neutron activation analysis using prompt gamma-rays, elemental analysis using neutron resonances, elemental analysis using fast neutrons, analysis of the elemental composition of thin films, investigation of the radiation resistance of materials to the effects of accelerated charged particles on electrostatic accelerator beams, development of radiation-resistant nanostructured materials using accelerated ion beams.

Expected results upon completion of the project:
Refinement of characteristics of known resonances and detection of previously unknown ones. Measurement of reaction cross sections and product correlations in the resonance region with an accuracy sufficient to study P- and T-odd effects.

Performing experiments to study TRI and ROT effects in fission, measuring the mass-energy and angular distributions of fragments, prompt neutrons and gamma-rays; searching for rare and exotic fission modes, using both IBR-2 and third-party sources.

Conducting experimental and theoretical studies of neutron-nuclear reactions in a wide range of energies of incident particles.

Study of the neutron dispersion law in a refractive medium, including in the case of high accelerations.

Development of models for calculating the transport of UCN and CN in the material of nanodiamond reflectors and the extension of their applicability to the range of thermal neutrons.

Study of the structure of graphites after their intercalation and measurement of cross sections for cold neutron scattering by intercalated graphites.

Obtaining data for nuclear power engineering and astrophysics: measurement of integral and differential neutron cross sections, angular correlations in the energy range from cold neutrons to hundreds of MeV.

Study of radiation resistance of various materials, including those promising for use as neutron reflectors and moderators. Development and study of radiation resistance of electronic components, including those operating on new physical principles.

Development of energy and electronics devices using powder nanotechnology and ion beams.

Obtaining new data and monitoring the environmental situation in certain regions of the JINR Member States with the help of NAA.

Study of the influence of neutron irradiation on the properties of biological objects and tissues.

Investigation of layered structures, including high-temperature superconductors using RBS, ERD and PIXE techniques.

Performing elemental analysis of various objects of cultural heritage.

Expected methodological results:
Determination of optimal technologies for the synthesis and modification of substances for use as UCN and CN reflectors.

Development of methods for cleaning water and soil, and assessing the quality of food products.

Study of the processes of accumulation of nanoparticles in the organs of animals and plants, assessment of their impact on the health of living objects under study.

Development of a technique for non-destructive elemental analysis using prompt gamma-rays. Improvement of existing methods of activation analysis using thermal and resonance neutrons.

Development of methods for analyzing the electrical properties of developed electronic devices, power engineering devices, and ionizing radiation sensors based on new physical principles. 

The fundamental results obtained during the implementation of the project will be of great importance for understanding the mechanisms of neutron-nuclear reactions and the development of theoretical ideas about these processes. The study of P- and T-odd effects will provide information on the contribution of the weak interaction to nuclear forces and can serve as an alternative method for determining the mixing coefficient Vud of a CKM matrix. Obtaining new information about ROT and TRI effects, as well as exotic fission modes, will make it possible to clarify the features of one of the stages of this process – the scission of a fissile nucleus into fragments. The data obtained during the implementation of the neutron-optical part of the project will be needed to create new neutron moderators and reflectors. In addition, they will allow significant progress in the development of neutron microscopy methods and studies of the magnetic structure of various objects. The implementation of the applied research program of the project will be of great social importance and contribute to the progress of environmental, materials science, archaeological, and nanotechnological investigations, as well as promising developments in the field of modern electronics and energy. The techniques of elemental and structural analysis being created and modernized will be in demand in many branches of human activity.