Seminars

Keeping reference points

On 12 February, a seminar of the Department of Nuclear Physics of F LNP was held on the occasion of the 70th anniversary of Candidate of Physical and Mathematical Sciences, senior researcher Ivan Ruskov (INRNE BAS, FLNP JINR). In his report "Interaction of neutrons with atomic nuclei", the hero of the day shared his 45-year experience in experimental investigations of the interaction of neutrons of different energies with atomic nuclei carried out at different neutron sources - IRT 2000, IBR-2, IBR-30, GELINA and ING-27.

"Today, we have a pleasant occasion," the Leader of the seminar Valery Shvetsov opened the seminar. "Our old friend and colleague Ivan Ruskov met his eighth decade. On 18 January, he turned 70 years old, on the occasion of which JINR Director Grigory Trubnikov issued an order, in which the contribution of the hero of the jubilee to research in fission physics and to strengthening the cooperation between the scientists of INRNE BAS and JINR was highlighted."

Valery Shvetsov presented the hero of the jubilee with gifts from his colleagues.

Ivan Ruskov began his speech with words of gratitude to the senior comrades and colleagues present at the seminar, first of all, to JINR Vice-Director L.Kostov, V.I.Furman and V.N.Shvetsov. According to Ivan's story, he was a worker and peasant and after graduating from high school, he joined the army, where he served as a junior sergeant in an elite tank brigade near Sofia. After completing his military service, in 1976, he entered the Faculty of Physics at Sofia University "St. Kliment Ohridski", Department of Atomic Physics, followed by postgraduate studies and a PhD at FLNP in 2000.

Since 1982, he has been working as a physicist at JINR and INRNE BAS in Sofia. In 1990, I. Ruskov was sent to work in FLNP, where he was engaged in fission physics. Ivan Ruskov did not forget to mention his teachers - Bulgarian professors and academicians, many of who were related to JINR: Academician Hristo Ya.Hristov (JINR Vice-Director in 1968-1970, Rector of Sofia University, founder and Head of INRNE BAS in 1973-1988), Prof. Ivan Zlatev (Dean of the Physics Department of Sofia University, Plenipotentiary Representative of the Bulgarian Government at JINR in 1973-1983 and later, JINR Vice-Director) and others, remembered his colleagues at INRNE.

During his service in the army, his reference point No.1 was the ventilation stack of the IRT-2000 research reactor of INRNE, where Ivan went on a tour later, already a fourth-year university student. By the way, on the second slide of his report, he posted a photo report thanking the schoolchildren of Gymnasium No.295 of St. Petersburg that had recently been on an excursion to JINR and that had also visited FLNP.

After graduation, Ivan joined the dosimetry group at the IRT 2000 reactor, where he was engaged in the combined personal dosimetry system, afterwards, in the metrology of mixed neutron-gamma fields. After the shutdown of IRT 2000, he was sent on a business trip to FLNP, where he worked intermittently for 18 and a half years. We have seen the first editions of the hero of the jubilee together with his colleagues and photos of Heads of the Laboratory in the 1990s: V.L.Aksenov, V.I.Furman, S.V.Kozenkov, V.I.Lushchikov, L.B.Pikelner, Yu.S.Zamyatnin. In the first year of his business trip to FLNP, Ivan participated in the VI International School on Neutron Physics in Alushta that was attended by A.A.Goverdovsky (IPPE, Obninsk) and E.Dermendzhiev (INRNE), the future supervisors of his PhD thesis. After the photos from Alushta, we saw the participants of ISINN conferences, the hero of the jubilee at the experimental facilities at IBR 2 and IBR-30, some of the staff members of the Department of Radioelectronics and Computer Engineering that provided technical support for the experiments at FLNP.

During these years, I.Ruskov together with colleagues from FLNP and IPPE (Obninsk) studied fission under the impact of resonance neutrons at the FP3/60m base of the IBR-30 pulsed reactor. A series of experiments were carried out to study fluctuations of fission gamma-ray yields in neutron resonances, as well as to measure fission cross sections of the main actinides: uranium-233, uranium-234, uranium-235, neptunium-237 and plutonium-239. The experimental facility IZOMER on IBR-2 was developed to study the emission of delayed fission neutrons. The results of the first measurements were reported at several conferences and published in the journal "Atomic Energy" in 1995.

In 2000, I.Ruskov successfully defended his thesis "Fission of neptunium-237 using resonance neutrons" for the degree of Candidate of Physical and Mathematical Sciences. In the paper, a lot of experimental data, statistical correlations between them and experimental estimates were obtained for the first time. In the same year, his term of work at JINR ends and at the invitation of F.J.Hambsch, Ivan starts to be engaged in precision measurements of reactions under the impact of neutrons on the time-of-flight spectrometer GELINA of the Institute for Reference Materials and Measurements (Belgium) as a national expert. As an associate professor at INRNE, I. Ruskov was engaged in peer-reviewing scientific articles for leading physics journals. Ivan Ruskov has always maintained close contact with FLNP and in 2010, he returned here. As a senior researcher at the Department of Nuclear Physics, he was actively involved in the TANGRA project, in which 14 MeV tagged neutrons are used for fundamental and applied nuclear physics research.

Ivan Ruskov presented numerous graphs with the obtained results, schematics of pulsed gas ionization chambers and multidetector systems, as well as pages of editions in various Russian and international publications. Like any other speech of Ivan, this report was full of archive photos, not so much of the hero of the jubilee, but of his colleagues in the laboratory - Russian and Bulgarian, from IPPE, PNPI, "Kurchatov Institute", foreign centres, from numerous conferences, biographical information about some colleagues that passed away. "Ivan, is half a millimeter enough for you, or do you need more pumping? Probably, it is enough. Thank you very much, Comrade Major!" What's that about? About the vacuum level in the neutron tube of beamline 3 of IBR-30. And who is "Comrade Major"? He is V.F.Shesterikov, an employee of FLNP, a cadre military man that went through the Great Patriotic War and was awarded orders and medals. The tank unit in which he served participated in the liberation of Bulgaria and reached the town of Stara Zagora.

At the end of his report, the author launched a video of the Volga embankment to the recording of the song "The Volga river flows" performed by Lyudmila Zykina. And on the slide, there was written: "17 is not 70" and "calmness and patience". The latter can be interpreted as the author's wish to all of us.

Olga TARANTINA,
photo by Konstantin KHRAMKO