Seminars

Such an essential fifth element

On 27 August, a seminar of the Department of Nuclear Physics was held at FLNP, at which a member of the TANGRA collaboration Ivan RUSKOV (Institute for Nuclear Research and Nuclear Energy, BAS, JINR) made a report "The Fifth Element".

Another popular science lecture from the series "Zamyatninki" given by Ivan was dedicated to boron - an element that as the speaker said in the abstract to the speech is in the focus of modern science and applied research. Boron and its compounds play an important role in various fields such as nucleosynthesis, fusion and fission technologies, military affairs, radiation protection, control systems, nuclear medicine and life sciences.

First, I.Ruskov made a small retreat, dedicating five minutes to rhenium and a possible future research area at FLNP. Rhenium is a by-product of the extraction of copper-molybdenum concentrate. "Phyto-production" of rhenium is its extraction from spent habitats using plants capable of accumulating metal components in extremely large quantities. The speaker compared the possibilities of estimating the concentrations of elements using neutron activation analysis at the REGATA facility of IBR-2 and other analytical techniques.

Bohr closes the top three Li-Be-B, the first two elements of which I.Ruskov spoke about at previous seminars. Boron is used in permanent neodymium magnets, in the production of high-strength glass, for example, for photovoltaic panels, in the production of microcircuits. Boron fibers and composites are used in aerospace structures, armor and bulletproof materials. It is widely used: from nuclear reactors and special devices to chemical fertilizers, insecticides and detergents, in boron neutron capture therapy for cancer.

After diamond, the B₄C boron carbide is the hardest material known to mankind. With a relatively low density, it is well suited for ballistic protection and is therefore used for tank armor. Boron compounds with aluminum, titanium and copper are strong, corrosion-resistant materials. The strength of boron carbide at extreme temperatures makes it an ideal choice for use in aircraft and space engines where reliability and efficiency are required in challenging environments.

At the seminar, information was voiced about the state importance of the extraction and processing of rare and rare earth elements both in Russia and in the USA, that the chemists of the Kola Scientific Centre of the Russian Academy of Sciences developed the first plant in Russia for the production of boric acid from liquid waste from nuclear power plants.

In 2023, the ITER organization decided to use tungsten for the front panel of the reactor instead of highly toxic beryllium. Boron (boration) will be used to absorb oxygen that can affect plasma quality. And Iranian scientists investigate LiBH₄, an innovative material for protecting against neutron radiation. Chinese physicists study the cost-effective processing of boron sludge, a byproduct of the boron industry, into valuable radiation-protective composites using inexpensive and simple technologies.

Boron is a highly reactive element that reacts violently with air and water, releasing a huge amount of heat. It is widely used in rocket fuel - from liquid (for jet engines) to solid (for hypersonic rocket engines). Given the modern race for hypersound, interest in new boron-based fuels has revived in China and the United States.

Along the way, we learned the origin of the unit of measurement of the nuclear reaction section - the barn. The term was coined by two American physicists M.Holloway and C.P.Baker that participated in the Manhattan Project. At first, they looked for a suitable first or last name among famous people concerning the research in this area. But all attempts were unsuccessful and after the next proposed name caused an association with the name of the toilet in colloquial English, the rural past of one of the physicists suggested the term "barn". The term was published in a secret report from Los Alamos in June 1943. 1 barn is equal to 10^-28 m² or 10^-24 cm² or 100 fm². We have also heard more recent information from Los Alamos National Laboratory about implementing critical mass measurements of nuclear charges in October 2017 without transfer to critical mode. And here, the boron-10 isotope is the perfect choice. It does not divide and is stable, but has a convenient property - in most cases, when its nucleus captures a neutron, it emits one gamma quantum.

Ivan also recalled the memorable date of our history - on 29 August, 1949, the first atomic bomb was tested in the USSR. In its design, a charge shell made of powdered boron was used. Boron carbide will be used in a possible future IBR-4 reactor - in the control and protection system.

Boron is also used in microchips of computers for quantum computing. Cubic boron arsenide is a new semiconductor with exceptional thermal conductivity and high carrier mobility.

In the ESS neutron source under construction, gas-ionization detectors based on boron-10 film will be used. In recent years, promising detectors with neutron converters based on B₄C boron carbide have been developed, not only for neutron investigations, but also for radiation monitoring systems. I.Ruskov presented several investigations, including those carried out in FLNP - on the manufacture and testing of a gas detector of slow neutrons and a position-sensitive monitor detector of slow neutrons with solid-state converters made of boron carbide B₄C. Also, a pilot experimental site for the manufacture of neutron detectors has been developed at FLNP.

The speaker presented some interesting from his point of view experimental investigations of the interaction of neutrons with ¹⁰B and ¹¹B isotopes. Focused on the need to obtain more reliable and accurate neutron-nuclear data, including within the framework of the TANGRA international research project. So, the IAEA held a technical meeting on neutron data standards in January this year. The required activities for the next issue of standards, including the status of the n+¹⁰B (¹¹B) reaction section measurements and the ¹¹B analysis work plans were discussed at the meeting.

Another business trip of Ivan Ruskov to JINR ended. "We hope that cooperation will be carried out in future," Head of the Department of Nuclear Physics of FLNP Valery Shvetsov said, closing the seminar. And many, I think, will agree with him.

Olga TARANTINA,
photo by Pham Khak Tuen (FLNP)