Discussing nuclear physics extensively

News, 04 March 2021

The 53rd meeting of the Programme Advisory Committee for Nuclear Physics was held on 22 January chaired by Professor M. Lewitowicz.

V. Utyonkov reported on the first experiment at the Superheavy Element Factory (SHE Factory) in FLNR JINR, which was conducted at the DGFRS-2 separator and aimed to synthesize isotopes of element 115 (moscovium) in the reaction 48Ca + 243Am. During the three-week experiment, more than thirty events of the decay of 288Mc and 289Mc were obtained, and this doubled the statistics on these isotopes collected earlier at the U-400 accelerator complex in 2003-2012. Further programme of experiments at the SHE Factory includes the increase in the intensity of 48Ca beams at the targets up to 3,0–5,0 pμA (completion of the creation of differential pumping and transition to larger targets). The programme also includes experiments on the synthesis of Fl isotopes in the reaction 242Pu + 48Ca and testing of 50Ti acceleration modes to prepare experiments on the synthesis of elements 119 and 120. The Committee congratulated the FLNR team on the successful start of the implementation of the SHE Factory’s experimental programme. The Committee also recommended completing the creation of the differential pumping system at the DGFRS-2 separator and a large-area rotating target as soon as possible to make experiments at extremely high-intensity beams possible.

V. Chudoba reported on the first experiments at the ACCULINNA-2 fragment separator which focus on the study of the super neutron-excess nucleus 7Н in the reaction 2H(8He, 3He)7H. The cross-section of this reaction is small. However, experimenters took all necessary measures to collect statistics at the ACCULINNA-2 facility. The analysis of the data made it possible to conclude that the ground and excited 7H state was observed. Moreover, researchers studied excited states in other exotic nuclei, such as 7He, 9He, and 10Li. Nowadays, the data analysis is underway, and the results will be presented at the next meetings. PAC assigned the ACCULINNA-2 experimental programme to the category A.

A. Doroshkevich presented a proposal to open a new project “Modernization of the EG-5 accelerator and development of its experimental infrastructure” and noted the exceptional importance of this facility for JINR. PAC recommended opening the new project on the EG-5 modernization in 2022 and creating relevant experimental infrastructure in the frames of the topic “Investigations of neutron nuclear interactions and properties of the neutron” for one year. If funding is available, the project may be prolongated for another two years. PAC assigned a B category to the project.

PAC listened to the report by P. Zarubin on the BECQUEREL project aimed at the study of dissociations of relativistic nuclei using tracks in nuclear emulsion (NE). Researchers studied nuclear fragmentation with the formation of stable and radioactive isotopes in the experiment at the Nuclotron. An important part of the project is training of young scientists. The analysis of experimental data and its interpretation allowed several young researchers to defend their candidate dissertations. It is expected that the implementation of plans for automation of data processing will lead to a considerable increase in statistics. PAC acknowledged the uniqueness of the NE method for the identification of charged particles at relativistic energies. However, compared to other methods, nuclear emulsions are less competitive. So, the BECQUEREL project got only the C category.

The project “Study of deep subcritical systems controlled by the accelerator and the peculiarities of their application for energy production, transmutation of radioactive waste” (E&T&RM) (S. Tyutyunnikov, E. Levterova) is devoted to the study of reactions in a uranium target irradiated with deuteron beams and protons at the Phasotron. Interesting results on the observation of high-energy and high-intense neutron emission from the surface of nuclear assembly may be used for the transmutation of spent nuclear fuel (SNF). The project’s goal is to create an experimental facility with a “quasi-infinite” target. A wide range of nuclear data will be necessary to determine optimal parameters of an innovative neutron source. PAC recommended that work on the E&T&RM project continues in 2021 and gave it the B status.

E. Yakushev made a report on the implementation of the topic “Non-accelerator neutrino physics and astrophysics”. The topic includes seven projects aimed at the study of rare phenomena related to weak interactions in which methods of modern nuclear spectroscopy are applied. The implementation of all the projects is united by common available resources and scientific approaches. In addition to the scientific staff, this topic includes the following resources: the laboratory for the production and repair of semiconductor detectors, the radiochemical sector, mechanical workshops, the computer support group for experiments, the mass separator group, etc.

PAC was satisfied to note international recognition of the team that greatly contributed to the creation of the setups, modeling, and data analysis, as well as its ability to lead and take part in world-class experiments. PAC supported plans for further development of the topic as far as participation in prestigious international projects provides access to advanced developments for the improvement of domestic neutrino experiments at the major experimental bases, namely in the laboratories at Kalinin Nuclear Power Station and on lake Baikal. PAC recognized the Baikal-GVD project as important being one of the JINR’s flagship projects and recommended prolonging the topic “Non-accelerator neutrino physics and astrophysics” until the end of 2024 with the first priority.

Materials prepared by Evgeny Molchanov
JINR Weekly Newspaper