At PAC meetings

About development of infrastructure and new projects

On 19-20 June, the 61st meeting of the Programme Advisory Committee for Nuclear Physics was held at the International Conference Centre.

Chairman of the PAC Valery Nesvizhevsky presented a report on the implementation of the recommendations of the previous meeting of the PAC. JINR Vice Director Sergey Dmitriev informed about the resolution of the 137th session of the Scientific Council (February 2025) and the decisions of the Committee of Plenipotentiary Representatives of Governments of JINR Member States (March 2025). The PAC highlighted with satisfaction that the recommendations of the previous PAC meeting on JINR nuclear physics research had been accepted by the JINR Scientific Council and Directorate.

The participants of the meeting were delivered a report on the state of research on the chemical and physical properties of superheavy elements (SHE) in FLNR, presented by A.V.Isaev. A four-week experiment aimed at studying the chemical properties of the superheavy elements Cn and Fl using gas adsorption thermochromatography at the modernized Cryodetector facility located in the focal plane of the GRAND separator of the SHE Factory was completed. Currently, experimental data is analyzed at the Cryodetector facility. In addition, test offline measurements are carried out on a gas catcher and development of design documentation for elements of a multi-reflection time-of-flight mass spectrometer (MR TOF) for precision measurement of SHE masses is currently carried out.

The significance of further investigation of the physical and chemical properties of the heaviest elements on the operating separators and the other ones under development, as well as detection systems of the SHE Factory was highlighted. The PAC recommended to carefully study and work out the issue of implementing experiments using extremely high intensities of accelerated ions and to focus on the issues of the effect of super-intense ion fluxes on materials and equipment of physical facilities.

An interim report on the status of the project "Modernization of the EG-5 accelerator and the development of its experimental infrastructure" at FLNP for the period from 2023 to 2025 was given by Alexandr Doroshkevich and the progress was highlighted. The EG-5 electrostatic accelerator is one of the JINR basic facilities and one of the most efficient and convenient tools in nuclear physics. At present, the basic service systems of the accelerator (vacuum system, gas cylinder facilities, others) have been updated on the EG-5 accelerator and passport technical parameters have been practically achieved. By the end of 2025, it is scheduled to resume the operation of the EG-5 accelerator in the basic configuration with the same ion source and accelerator tube and to enter the operating mode with an operating time of at least 1500 hours/year. The PAC recommended to resume work on the EG-5 in its basic configuration until the completion of the preparation of new components of the high-voltage system and the accelerator tube, as well as to implement the further upgrade of the EG-5 accelerator. The PAC recommended comparing the performance of the EG-5 accelerator with similar advanced facilities in the world.

The PAC members were presented proposals to open a new project "Development of the concept of an ultracold neutron source at the IBR-2 pulsed reactor" by German Kulin. The project aims at developing the concept of ultracold neutron (UCN) source of international standard at the IBR-2 pulsed reactor. The conceptual design of the source will be based on a number of engineering solutions that have no analogues in world practice. At the end of the project, a prototype source will be developed. The PAC emphasized that development of a world-level UCN source at JINR is an essential task and recommended opening a new project for a period of two years (2026-2027).

The PAC was presented proposals to open a new project "Development of test benches for testing individual systems of the MSC-230 cyclotron," delivered by S.L.Yakovenko. Development of the medical superconducting cyclotron MSC-230 and research infrastructure will allow at a new level to implement further research in the field of proton beam therapy that was previously carried out on proton beams of the JINR phase proton. The supposed high intensity of the proton beam in a steady mode and a pulsed mode will allow the investigations to be carried out with a new technique of radiation therapy known as flash therapy.

The PAC emphasized with satisfaction the achievements in the preparations for the launch of MSC-230, welcomed the ambitious plans to launch the cyclotron in 2026 and highlighted the importance of developing new infrastructure at JINR for implementation of radiobiological research. The PAC recommended opening a new project.

At the meeting, the report "Achievements in the description of spontaneous division of transfermium nuclei" was presented by T.M.Schneidman and "Nucleon and cluster transmissions in reactions with nucleus ⁹Be" - by A.K.Azhibekov.

The young scientists from BLTP and MLIT presented six short messages on nuclear physics. Members of the PAC awarded the three best reports: "Low-energy properties of nobelium" - M.A.Mardyban, "Alpha decay and spontaneous fission of superheavy elements in the framework of the DNS approach" - I.S.Rogov and "Investigation of the spectral structure of ¹¹Be in collapse reactions in a quantum quasi-classical approach" - D.Valiold. The PAC recommended the report "Low energy properties of nobelium" for presentation at the session of the JINR Scientific Council in September 2025.

Nikolay SKOBELEV,
PAC Scientific Secretary for Nuclear Physics