At PAC meetings

Reactor started operating, spectrometers improved

On 26 June, the 61st meeting of the PAC for Condensed Matter Physics was held in a mixed format. The Committee members reviewed the implementation of the recommendations of the 60th meeting of the PAC, the resolution of the 137th session of the Scientific Council and the decisions of the PAC meeting.

The report "Current status of the IBR-2 reactor and the final report on the project "Development of the IBR-2 nuclear research rector with a complex of cryogenic neutron moderators" and the subproject "Development of a complex of cryogenic moderators of the IBR-2 reactor" was delivered by Egor Lychagin. Here's how he commented on his report:

Egor Lychagin

- The most important news is that the reactor started operating after a long shutdown that has never happened in its history - more than three years. We were a little worried about how it would behave after such a long break but practice has shown that everything is fine with it. It can operate stably at a capacity of up to one and a half MW that is what we schedule. The possibility of increasing the power above the design (2 MW) requires further research. In spring, we announced submission of applications for the autumn-winter series of cycles. We did not know how users would respond after such a break, although we tried to disseminate information about the resumption of reactor operation as widely as possible. There were experiences but the number of applications turned out to be the same as before the shutdown - a little more than 100 for six months. The geography of users has changed: the number of applications from Europe has decreased: from Poland, Romania, the Czech Republic. Suddenly, Armenia was in the second place among new users and as expected, Egypt showed its interest, becoming a full member of JINR.

After much discussion, we have come to the conclusion that at least today, there is no need to design a third cold moderator. Today, the developed complex of cryogenic moderators that consists of two moderators and two cryogenic machines satisfies us and we want to fix this configuration. Maybe after a while, we will return to this issue but today, we believe that the complex has been established.

An information on the progress of work on a new neutron source was requested by the PAC members, we are ready to make a special report on this topic at the next meeting. Work on preparing documents to justify the new source is underway: what kind of science will be done on it, what tools we are going to construct for it and what the source itself should be. A few days ago, we published the first part of this justification - a description of the scientific research areas that we intend to develop at a new source. I hope, the Programme Committee members will study it and give us advice. Some of them have read this text in preparation and have made comments. I am grateful to all the laboratory staff engaged in writing this paper and supervised S.A.Kulikov and N.Kucherka on the first volume.

Has the situation with experts involved in the selection of proposals for experiments not improved?

- The situation with experts is as follows. We try to keep these groups international. Not all countries have developed science in the field of neutron scattering - the list of countries which we can attract experts from is limited. The second limitation: even those countries where there is a developed science on neutron scattering, especially European ones, have formal restrictions not to cooperate with JINR, with scientists from Russia. For these reasons, our previous expert committees that worked before the reactor shutdown, practically ceased to exist. We have assembled four new committees. The last round of examination of proposals for experiments showed that it is difficult for two of them to work: they have nine experts each, who a rather large load has fallen on. We had to slightly increase the examination time and we would like to strengthen these groups. Therefore, I have been asking Committee members for two years to advise us who we could cooperate with in this area. Today, our expert groups have expanded: experts from Korea, South Africa, China, India have appeared.

A.I.Ivankov told about the current state of the YuMO small-angle neutron scattering spectrometer. The first results of the spectrometers complex after the resumption of operation of the IBR-2 reactor were summed up by D.P.Kozlenko:

Denis Kozlenko

- After more than three years, the operation of the IBR-2 reactor resumed. We used this time to modernize the facilities of the spectrometers complex. Quite a lot has been done: new detectors for spectrometers, sample environment systems have been developed, components of the neutron guide systems have been replaced that will improve the parameters of the facilities and will expand the technical capabilities for implementing experiments. Therefore, the main goals that we set for ourselves in the first test cycles of this year are first of all, to complete the modernization, to put the new components of the facilities into operation, to carry out the first experiments and to begin the scientific work on a complex of spectrometers.

In general, much of the scheduled work has been completed. The High-Resolution Fourier Diffractometer was used to launch a new backscattering scintillation detector, developed in collaboration between two departments - DSC and DNICM. It will provide coverage of a large solid angle, about 10 times larger than the old detector that will significantly improve the parameters and capabilities of the facility. The detector will achieve the same high resolution in structural investigations as before, at the level of 0.1 percent. This work will be carried out in future, as there is a need to improve data storage electronics. Due to the fact that the detector has a very large area, the available electronics could not cope with the new amounts of data. It is assumed that in the coming months, the work will be completed, after which it will be possible to start full-fledged scientific activity.

On the FSD diffractometer, a new detector system with an increased solid angle was also put into operation, developed in DSC in collaboration with DNICM. It operated well but there were similar tasks with electronics that we meet. The new data storage electronics are generally developed and currently undergo testing, after which it will be possible to resume full-scale experimental work.

Modernization has also been widely carried out on diffractometers to study the crystalline and magnetic structure of materials at high pressures. The central part of the neutron guide system DN-6 was replaced at the facility that improved the average neutron flux on the sample by about two times. It will expand our capabilities for unique experiments with ultra-high pressures in the future up to half a megabar (500 thousand atmospheres), experiments of this level can be carried out only in a few advanced world neutron centres. Another component of the detector system has also been developed that will allow us to expand the possibilities of studying magnetic structures under pressure.

Work on the reconstruction of the EPSILON diffractometer is underway. After the completion of work at this facility, research in a new area related to the textural analysis of cultural heritage sites is shceduled. Our department has been implementing research on cultural heritage objects for a long time in cooperation with various organizations, in particular, with the Institute of Archeology of the Russian Academy of Sciences. The main techniques are radiography and tomography and it is assumed that the investigation of the texture of such objects will provide extra relevant information. Of course, on this facility it will also be possible to carry out traditional for our laboratory investigations of the texture of various geophysical, structural materials. Also, on another, SKAT diffractometer for texture investigations, a second detector ring and an additional goniometric sample node were designed. It will allow simultaneously measuring the texture of two samples and increasing the number of experiments implemented.

At a number of facilities, significant modernization was not carried out; there were both methodological and scientific experiments implemented on these facilities. A number of methodological experiments were carried out at the YuMO facility, investigations of biological objects were implemented. The vibrational dynamics of materials used in pharmacology and medicine, ketoprofen and ibuprofen were studied on the NERA facility. Various functional materials, such as copper-doped nanostructured zinc oxides were studied on the RTD diffractometer. Such compounds have wide prospects of practical use, for example, as photocatalysts. Work on the modernization of the detector system and scientific experiments were carried out on the DN-12 spectrometer - the structural and magnetic properties of magnetite nanoparticles doped with rare earth metals were investigated.

In addition, despite the fact that the resumption of a full-fledged user programme is scheduled only this autumn, a number of applications have been submitted in the framework of a fast user access system for short experiments.

In general, the results obtained in the test cycles showed that the modernization carried out will significantly improve the efficiency of several spectrometers, expand experimental capabilities and ensure an increase in the number of experiments implemented at a number of facilities.

Pavel Alekseev

The first reports were commented on by a member of the PAC P.A.Alekseev (NRC "Kurchatov Institute"):

- It's great that the project to develop cold moderators for IBR-2 has been successfully completed. Cold neutrons are important in condensed matter physics, biological and other research. The idea is original, the execution is good, the sources have operated - everything is great and we will obtain good results. The fact that the reactor was revived is also very important, since there is no other one yet. Throughout the country, this is still the only neutron source actually operating for experimenters.

As for the new neutron source to replace IBR-2, the initial idea was great: a new level source based on a short-flash accelerator that would provide an even wider range of experimental tasks. When the accelerator was abandoned for technical reasons, they came up with the idea of a reactor based on a new fissile material - neptunium instead of plutonium. Now, it turns out that this line of retreat could not resist, as far as I understand. But the new reactor should operate - what kind it will be, it does not matter. There will be one and a half to two times more neutron flux - and thank God.

It is wonderful that in JINR, the opinion of the Scientific Council and of our Programme Committees is important for Directorate. Dubna seems to be one of the few places in the country where if the Scientific Council decides, Directorate performs, the Plenipotentiaries have approved - and very good. This is the main happiness of those who work in Dubna. At your Scientific Councils, they actively discuss issues of science, when I had occasion to participate in them - it was very pleasant and I was happy for JINR employees.

Two scientific reports were delivered at the meeting - "Magnetism and superconductivity in periodic and quasi-periodic low-size layered systems" (V.D.Zhaketov), "Conformational dynamics of Aβ-42 in the liposome at different pH values: a combined spectroscopic and computational approach" (E.Arynbek), a poster session of the papers of young scientists of FLNP in condensed matter.

We will give the final word to the PAC Chair Professor Denes Nagy.

The meeting was unusually short. Perhaps due to the fact that the reactor did not operate for more than three years, new topics were not opened, a report was made on the closing topic in the framework of the report of FLNP Director on the current status of the reactor. The first results of the spectrometers after modernization were summed up by D.P.Kozlenko. How did the PAC estimate them?

- Indeed, on 16 October, 2021, the IBR-2 reactor had to be shut down due to a leak in the secondary cooling circuit of the air heat exchanger and after a lengthy permit procedure, the facility again became critical on 17 February, 2025. Although we expect the regular user programme to resume only in early 2026, the call for submission of beam time applications in 2025 was announced without any delays and the submitted applications were evaluated by scientific experts in the last days of May and early June. As for Dr. Denis Kozlenko's report, it was welcomed quite well by the PAC members.

The meeting of the Committee members with Directorate seemed to me very short. Were there few topics to discuss or did you discuss them fast?

This was a consequence of the unfortunate circumstance that neither JINR Director Grigory Trubnikov, nor Professor Latchesar Kostov, due to other urgent matters, were able to take part (even remotely) in the meeting of the PAC members with JINR Directorate. Since the meeting was scheduled prior to the main reports of the meeting, we had to discuss items on the agenda of the PAC meeting that had not been implemented yet. Of course, it is nonsense and I really hope that in the future, there will be no such situations.

Only four papers by young scientists were presented in the poster session. This time, there was no problem choosing the best poster?

- The poster session this time was organized in a completely new way. First, a preliminary selection was carried out in laboratories and four oral reports were delivered at the PAC meeting. After the voting of the PAC members, the report "Automated segmentation of pores and cracks in neutron, synchrotron and X-ray tomographic data using the UNet 3+ convolutional neural network" by Bulat Bakirov (FLNP) was recognized as the best report of the meeting. The author will be awarded a PAC diploma at the next meeting. There was a discussion about whether we should use this technique in the future, yet apparently, at the next meeting in January 2026, we will not change the procedure. One thing's for sure though: we'll never go back to print posters, that approach is definitely a thing of the past.

Olga TARANTINA,
photo by Igor LAPENKO