21st century projects

By uniting efforts

This summer, the annual meeting of the RAS Scientific Council "Relativistic physics and heavy ion physics" was held in St. Petersburg. Chairman of the Council and FLNR Scientific Leader Yu.Ts.Oganessian delivered a report titled "Heavy ions in science and technology". The organizers of the annual Baldin International Seminar on High Energy Physics, held in September, invited him to repeat this report, with minor modifications and additions, at the opening of the seminar.

As Yuri Tsolakovich Oganessian explained in his speech at the Council that has been held annually for five years now, he usually describes and shows what has been accomplished in heavy ion physics over the past one or two years, what is scheduled for the near future and comments on the results of the latest experiments, all of which is then discussed at the meeting. He also presented this overview to the seminar participants. Beginning with the synthesis of new elements and isotopes, the speaker highlighted that major changes are expected in the periodic table after the synthesis of element 121. And what it will look like is to be seen. Today, the synthesis of new elements is scheduled in programmes at nuclear centres and national laboratories in Japan (RIKEN), the USA (BNL), Germany (GSI), France (GANIL) and our own JINR, where different but related reactions are currently carried out. "We chose perhaps the most complex reaction, Bk-249 + Ti-50, since the half-life of the Bk-249 target nucleus is only 320 days. This unique substance is produced in the core of a high neutron flux nuclear reactor over the course of a year. At least another year will be needed to carry out the first experiment. We have no room for error or interruption," Yu.Ts.Oganessian emphasized. Berkelium is currently produced in Dimitrovgrad and then a target will be manufactured. The experiment itself is scheduled for 2026. "As of today, the experiment at RIKEN has been completed without result, while BNL hopes to obtain one or two events in a year of constant operation. I am skeptical, especially after the Japanese experiment. Over the past two years, a whole series of experiments have been implemented at FLNR, including those directly simulating the synthesis of elements 119 and 120. After the familiar fusion reactions with a Ca-48 ion beam, we should turn to the Ti-50 beam, the reaction cross section for which is 10 times smaller and our working conditions are becoming increasingly complex," he emphasized. Fortunately, the SHE Factory functions well, has reached its design parameters and the luminosity of experiments has increased tenfold.

The promising work at the Superheavy Element Factory was discussed in the Academician N.V.Zavyalov's report at the Council of the JINR-Rosatom Project "Synthesis of superheavy elements". Obtaining one or two new elements is no easy task but that's not the main goal. It's crucial to understand the limit of the availability of chemical elements and quantitative data on the nuclear shell effect of isotopes from Db to heavier elements are crucial. Yuri Tsolakovich focused on the physical and chemical investigations of heavy and superheavy elements in recent years. The relativistic effect increases significantly with increasing atomic number; in extreme cases, an element can "jump" out of its designated place in the periodic table. He also reported on the successful testing in China of the superconducting magnet for the GASSOL gas-filled separator, a new generation of separators developed at the JINR Laboratory of Nuclear Reactions. This magnet will be transported to Dubna and installed on the DC-280 accelerator beamline.

Focusing on the structure of the magic nuclei Ca-40-48 and Pb-208, Yu.Ts.Oganessian discussed new experiments at JLab and FRIB. Using the JLab facility, it was possible to see that Pb-208 has a fairly thick neutron skin layer, about 0.3 fermi. This result, fortunately, agrees well with current microscopic nuclear theory. A similar neutron layer was also expected for the Ca-48 nucleus. According to preliminary data (the experiment is ongoing), the neutron skin layer of Ca-48 is about twice as thick as that of lead. Reconciling this effect with nuclear theory will be the subject of further research.

Speaking about neutron-rich nuclei, he emphasized the recent experiments implemented at GANIL, RIKEN, FRIB, the LHC and JINR. "We should understand: the gauntlet has been thrown down to us - nuclear physics laboratories work on neutron-rich nuclei, while the Universe contains neutron stars with solar masses. There are one billion of them in our Galaxy alone! Nuclear theory is used to describe rapidly rotating neutron stars but it's not very suitable," Yu.Ts.Oganessian highlighted. Within the discussion, he proposed to his colleagues the task of studying the He-12 and Be-14 system using beams of C-12, O-16-18 and Ne-22 ions from the JINR ion synchrotron.

Head of the Department of Heavy Ion Physics at VBLHEP Aleksandr Malakhov:

"At FLNR, we work on the synthesis of superheavy, neutron-rich nuclei. Neutron-rich nuclei can also include helium nuclei, including He-12 that has not yet been synthesized. The synthesis of superheavy and light, neutron-rich nuclei shows unusual properties of neutron interactions. Yu.Ts.Oganessian came up with the idea of studying the He-12 system using the capabilities of the NICA complex that he described in our laboratory. We decided to use the complex - a booster plus the Nuclotron with a Be-12 beam produced on the booster's internal target by a C-12 beam. We have practically everything necessary for this experiment. This research area will be new for JINR and it is not yet well developed internationally.

The idea of a possible experiment was also discussed at the recent meeting of the RAS Council on Superheavy Elements. VBLHEP researcher S.V.Afanasiev presented a report "Neutron-rich nuclei at the NICA Complex". The booster and Nuclotron complex could be used to study light neutron-rich nuclei. The FLNR accelerators do not reach the required energies - more than 300 MeV/nucleon.

Of course, there are technical difficulties. The booster does not have beam extraction, while the Nuclotron does. A Be-12 beam should be extracted from the booster to the Nuclotron using the current standard equipment. The main challenge ensures that the accelerator complex staff obtains the required beam; much depends on it.

We currently prepare a proposal for a corresponding project for the 2026 Topical Plan and we have decided to begin measurements even before it is approved. We hope preparatory work will begin this autumn. We have the required equipment, the experiment is quite realistic.

Given the importance of the problem, Yu.Ts.Oganessian proposes discussing the development of a dedicated accelerator for the physics of neutron-rich light nuclei in the coming seven-year period, in order to develop a new research area at the Institute. It will further unite two JINR laboratories, although the new experiment will also involve staff members from VBLHEP and FLNR. Our energy capabilities unite us. This experiment is also important for the NICA project. The discovery of He-12 will be the first significant result in a series of experiments scheduled at the NICA complex."

At the Baldin Seminar, Sergey Afanasiev (VBLHEP) presented a report on the synthesis of neutron-rich nuclei at the NICA complex:

"Yuri Tsolakovich, at the beginning of the year, voiced the idea of producing neutron-rich nuclei at a seminar in our laboratory. They are of interest for many reasons, including space physics, heavy ion physics, isotope synthesis and other fields. It is, in principle, possible to produce an exotic neutron-rich nucleus, such as the He-12 nucleus. It can be done using the well-known double charge exchange reaction that changes the charge of the daughter nucleus by two units. To produce He-12, in this case, we need to use the isotope Be-12 but it only lives for 0.02 seconds. The reaction with Be-12 is well-known, so it's clear what to do but the problem is that Be-12, from which He-12 can be obtained, is a short-lived isotope. Accumulating it, accelerating it again and then implementing the next reaction is practically impossible. Therefore, we should produce it accelerated.

Today, we have the opportunity to meet this technical problem using the NICA collider's ring system - the booster and the Nuclotron. Be-12 can be produced by accelerating ordinary C-12 in the booster. The booster's purpose is to produce high-intensity beams of heavy, highly charged ions for NICA. To achieve it, a target is positioned at the beam exit from the booster, where excess electrons are stripped. This is convenient for our task because we can use this target not only to strip excess electrons but also to produce the beryllium isotope we need. By accelerating carbon nuclei to 500 MeV and directing the beam onto a thin foil, we thus charge-exchange carbon into beryllium and the resulting ions are extracted from the accelerator. Knowing the energy required for this reaction allows us to calculate the Be-12 yield. This technique allows us to produce a beam of short-lived isotopes needed for research. Along with them, of course, many other background particles are born that need to be gotten rid of.

Here, the Nuclotron's second ring helps us. Its magnetic system removes excess ions, reducing the background by tens of thousands of times. As a result, we obtain the desired Be-12 beam, which we can extract He-12 from. To determine whether it is indeed He-12, a spectrometer system is required. Such capabilities are already available for test measurements. A system of channels for applied research has been developed in the measurement pavilion adjacent to Building No.1. These channels are ideal for trial experiments with neutron-rich nuclei. Thus, we currently have everything we need for initial test measurements. For major experiments, optimization of all systems is necessary and a special fragment separator may be required. In general, using a booster as a source of radioactive ions opens up an extra avenue of research and this is a matter for the future. Today, we can check what the beryllium yield will be, how much He-12 we will obtain, test it and subsequently, it is quite possible, to establish a specialized factory similar to those currently operating at GSI and CERN."

Laboratory Directors spoke about the need for closer collaboration between the Institute's laboratories and more efficient use of basic facilities and other resources.

"Today, many things are only promoted thanks to major projects like NICA," VBLHEP Acting Director Andrey Butenko said. "We can't rest on our laurels and limit ourselves to well-established approaches. At FLNR, we've long dreamed of linear accelerators, even ring accelerators. This is also necessary for advancing FLNR's scientific programme but as far as I understand, there are no specialists in either linear accelerators or synchrotrons yet. The main thing is that they are available at the Institute. At the RAS Council, organized by Yuri Tsolakovich, FLNR was represented by seven exceptionally knowledgeable young people who will undoubtedly be able to expand their expertise into accelerator technologies that are still unfamiliar to the laboratory. FLNR now has a very good team. They have a staff rotation going on and in this regard, we have someone to look up to.

Yuri Ts. Oganessian's project will also serve as a catalyst for development at VBLHEP. Any new idea entails at least some mental activity, the "digestion" of new content. Just thinking about it, not designing it, already inspires people with different perspectives to come up with new ideas. A new proposal allows you to take a fresh look at what you're currently engaged in. Yuri Tsolakovich has a fresh perspective on our research complex for experiments with stationary targets. But to meet the task he's set, we still need to build a new complex - small, compact and efficient. In principle, we've even found a building where it can be done. But the next step requires some willpower and more in-depth development at the level of a real concept, after which a technical design will emerge. This is a process that doesn't yet require tasks for workers but it does require engineers, especially theoretical and experimental physicists. It's crucial that such ideas emerge. A huge thanks to him for shaking things up a bit at FLNR and getting us involved. Unfortunately, FLNR staff haven't been particularly involved yet but at least our specialists are already engaging with new ideas and challenges and have started generating some ideas. A.I.Malakhov's team, the accelerator specialists and other specialists - we're all still thinking about it, but I don't rule out the possibility that it will soon translate into some real solutions and technical design work will begin.

It's crucial that such ideas and challenges emerge and inspire new solutions and facilities. Why, you ask? Yuri Tsolakovich explains. And then we discuss how to do it and what needs to be built for it."

"JINR invests enormous resources, both material and human, in the development of new fundamental facilities such as NICA, Baikal-GVD and the Superheavy Electron Factory," DLNP Director Evgeny Yakushev agrees (DLNP). "Development of each facility requires the efforts of several laboratories and these efforts should be utilized and to the maximum extent possible, by researchers from different laboratories, pursuing their own research programmes. This is the foundation for our interlaboratory collaboration."

An example is the development of the medical proton accelerator MSC-230 at DLNP, in which we are supported by the Laboratory of Nuclear Reactions (FLNR), the Laboratory of High Energy Physics (VBLHEP) and the Laboratory of Radiation Biology (LRB) in implementing future biological research. Both the development of this facility and its future use are an interlaboratory project.

Yuri Tsolakovich has many brilliant ideas. Collaboration is scheduled between DLNP and FLNR to study superheavy elements using the knowledge of our specialists. FLNR develops superheavy elements and researchers from our two laboratories will study them. Several experiments are scheduled for the NICA accelerator under construction. The MPD experiment is currently carried out by researchers from VBLHEP and several other institutes and the SPD collaboration is headed by FLNR Deputy Director A.V. Guskov. It includes several hundred people from our laboratory, research centres in Russia and other Member States.

A significant component of the Institute's core infrastructure is the MLIT supercomputer and grid technologies that are used by all laboratories. JINR Director Grigory Trubnikov rightly declares the need to strengthen interlaboratory relations. It should occur in a natural way by developing facilities that will be operated by large staffs and utilized to their full potential."

Olga TARANTINA,
photo by Igor LAPENKO