Strutinsky, Vilen Mitrofanovich

Strutinsky Vilen Mitrofanovich
Strutinsky Vilen Mitrofanovich
Date of Birth
Place of Birth	Danilova Balka village, ; Ulyanovsk district , ; Kirovograd region , ; Ukrainian SSR
Date of death
Place of death	;
A country	;
Occupation	nuclear physicist

Vilen Mitrofanovich Strutinsky ( 1929 - 1993 ) - Soviet physicist. Member of the European Academy of Sciences and Arts (Trieste, 1991), member of the Council for Nuclear Physics of the USSR Academy of Sciences, member of the editorial board of the journal " Nuclear Physics ".

Content

Biography

Vilen Mitrofanovich Strutinsky was born on October 16, 1929 in the village of Danilova Balka, Ulyanovsk District, Kirovograd Region, in a family of a military man.

From 1930 to July 1941 he lived with his parents in Odessa . In 1941, together with his mother and brother, he was evacuated to the place of service of his father in the city of Sukhoi Log, Sverdlovsk Region. In 1942 he moved with his family to Sverdlovsk . In 1943 he was admitted to the Komsomol. In 1946 he moved with his family to Odessa, where in 1947 he graduated from high school and entered the Physics and Mathematics Department of Odessa State University . In 1951, on the orders of the Minister of Higher Education of the USSR, he was transferred to the fifth year of the Faculty of Physics and Mathematics of Kharkov State University , which he graduated with honors in 1952 with a degree in theoretical physics.

After graduation, Vilen Strutinsky in February 1953 by distribution was sent to work in the sector of the theory of the atomic nucleus of the Institute of Atomic Energy named after I.V. Kurchatova (supervisor - academician Arkady Migdal ), where he worked until 1970. He defended his thesis (1959, Moscow Engineering Physics Institute , Moscow) and the doctoral (1965, JINR , Dubna) dissertations. He went on business trips to scientific conferences on nuclear physics to Holland (1956), Canada (1960), and the USA (1963, 1964).

In 1957-1958 he completed an internship at the Institute of Theoretical Physics. Niels Bohr (Copenhagen, Denmark). In 1967, Strutinsky was invited to the Institute of Theoretical Physics. To develop the theory he created, Nilsa Bora worked there as a guest professor until the end of 1970, and then moved to Kiev, where until 1991 he headed the nuclear theory department of the Institute for Nuclear Research (INR) of the Ukrainian Academy of Sciences. In 1992-1993, he was the chief research fellow at the Department of Nuclear Theory, Institute of Nuclear Sciences of Ukraine.

Works

The first period of scientific work (1955-1956) by Vilen Strutinsky was associated with the development of new ideas about the structure of complex atomic nuclei due to the discovery of their non-spherical shape. His work on the theory of alpha decay , the specifics of the selection rules in deformed nuclei attracted wide attention of specialists. In them, Strutinsky independently established patterns in the probabilities of alpha decay, known as the Alagi rules. These works were the subject of his Ph.D. thesis.

The next series of works (1957-1961) is devoted to the classical interpretation of the quantum angular momentum , the rules of addition of quantum angular momenta ^[1] and the correlation between the orbital momentum of a particle and the direction of its motion. As a result, simple expressions were established for the angular distributions of fission fragments of a rotating nucleus (Halpern formula ^[2] -Strutinsky), the angular distributions of particles emitted from a rotating nuclear compound (Erickson-Strutinsky formula), and angular correlation in mixed-type processes, for example, during decay heated core formed in the stall reaction. These studies formed the basis of his doctoral dissertation.

In 1962-1963, Vilen Strutinsky performed a fundamental work (together with N. Ya. Lyashchenko and N. A. Popov), devoted to the quantitative description of the geometric forms through which the nucleus passes in the process of fission. It obtained a general solution to the complex problem of nuclear fission barriers and predicted the existence of critical deformation at which the nucleus breaks into two fragments. The basis of the work was the assumption that division has a quasistatic (infinitely slow) character. About 30 years have passed after this work was completed, when the discovery of intense nuclear friction gave a solid justification for precisely this nature of the process of fission of heated nuclear systems.

Subsequent works on fission theory showed the equivalence of the droplet model of deformed nuclei and statistical models using the energy density functional . The work of V. M. Strutinsky and A. S. Tyapin (1963) established a connection between the droplet model of the nucleus and the shell model with residual interaction. Namely, it was shown that the total energy of a nucleus of arbitrary shape, consisting of the kinetic energy of nucleons and the potential energy of their interaction, calculated with the semiclassical wave functions of nucleons, has the same structure ( volume energy + surface energy + Coulomb energy ) as the droplet formula Weizsacker .

These works revealed the need to take into account shell phenomena in deformed nuclei and served as the basis for the method developed in 1965-1968 by V. M. Strutinsky for calculating the total binding energy of the nucleus — the shell correction method , which was later named after him. In this method, the droplet model describes only the average behavior of the mass of the nucleus depending on its neutron - proton composition, against which the real masses noticeably deviate from the droplet in the region of magic nuclei . This behavior of the masses is explained by the peculiarities of the motion of independent nucleons in a closed volume of the nucleus. It was shown that the irregular component of the binding energy can be calculated in the framework of a relatively simple shell model of the nucleus.

V. M. Strutinsky theoretically predicted the existence of a developed shell structure of nucleon spectra ^[3] in strongly deformed nuclei (similar to the band structure of electronic spectra in crystals), which regularly occurs under certain deformations of the atomic nucleus. On this basis, the existence of an intermediate relatively stable very highly deformed state in heavy nuclei (uranium - California) was predicted. It turned out that the calculated actinide barriers (Z = 90–98) have a two-humped character, with a deepening between the barriers exceeding the bottom of the internal potential well by 2-3 MeV .

This discovery made it possible to solve many puzzles in the separation of actinides from hypothetical metastable states with low spin and excitation energy E *> 2.5 MeV, namely: the nature of such states, the characteristic modulation of compound-nuclear resonances in the reaction cross sections (n, f), ( d, pf) on actinides and the angular anisotropy of fission fragments. In addition, which is no less important, it follows from the discovery of V. M. Strutinsky that the modification of the droplet barrier due to the inhomogeneity of the single-particle spectrum can make stable (with respect to fission) nuclei with Z about 114 (superheavy elements).

The theory of V. M. Strutinsky allowed not only to explain many well-known features of the nuclear fission process, but also to predict new properties that are unexpected from the point of view of traditional representations of the Niels Bohr theory . Subsequent intensive research and experiments fully confirmed the theoretical conclusions of V. M. Strutinsky. The theory proposed by him for the first time made possible the quantitative prediction of masses, many properties of fissile nuclei and, in particular, the stability of superheavy nuclei. It has become widespread and is included in the main fund of nuclear physics .

In subsequent works by V. M. Strutinsky and his colleagues, it was shown that the shell or band structure of the spectrum of nuclei is a common property of finite Fermi systems. A quantitative relationship was established between the magnitude of shell effects and the symmetry of single-particle motion in the nuclear potential, qualitatively established patterns of change in the role of shells depending on the number of nucleons and the shape of the nucleus. Thus, those factors were identified that determine the non-sphericity and determine the equilibrium forms of heavy nuclei.

Using the method for calculating the masses of rotating nuclei led to the prediction of superdeformed quasistationary states arising at large angular momenta (V.V. Pashkevich, S. Frauendorf, 1976). An increase in the number of parameters for describing the shape of the fissile nucleus made it possible to predict the presence of two fission valleys in the region of preactinide nuclei, in one of which the nucleus passes through more compact forms than in the other.

Subsequently, superheavy nuclei, super-deformed quasistationary states with large spins, and the existence of several fission valleys were experimentally confirmed.

In some works of the 1970s V. M. Strutinsky returns to dividing subjects. Characteristic is the small work of 1974 in the journal Nuclear Physics, in which attention was drawn to the 1940 Kramers formula for dividing the width with respect to friction and, in this context, corrections were made to the Bohr - Wheeler formula for the dividing width in systems without friction.

The work of the 1980s is dominated by heavy-ion themes. The macroscopic (classical) and quantum-mechanical aspects of reactions with heavy ions are analyzed. An explanation is given for the first time of the properties of reactions that do not fit into classical concepts. A simple theory of nuclear reactions between heavy ions has been developed, taking into account the macroscopic and wave aspects, which is convenient for analyzing experimental data on quasielastic and deep inelastic reactions with heavy ions. In the framework of this theory, a deeper study of the mechanisms of interaction of heavy ions, in particular the study of quantum interference and resonance phenomena (the polarization mechanism and rotational states of nuclei, resonant scattering at large angles, and others), has been carried out. A detailed study of the statistical characteristics of the reactions revealed a connection between the fluctuation characteristics of polarization and the reaction cross sections.

A significant place among the works of V. M. Strutinsky and his employees is occupied by the development of the theory of collective motion in nuclei at large amplitudes and a finite value of velocity. In this field, they obtained fundamental results that are important for creating a quantitative theory of such nuclear processes. It is shown that with a large amplitude and a finite rate of deformation of the nucleus, redistribution of partially hole states occurs, corresponding to the transition to the macroscopic deformation mode and the formation of a dynamic ground state.

A new theoretical model of the dynamics of collective processes in heavy nuclei is proposed and created - the gas-droplet model of the nucleus (GCM). GCM consistently combines macroscopic degrees of freedom and quasi-partial excitations in nuclei. An effective core surface method has been developed for collective dynamics problems. In the semiclassical GKM approximation, solutions of the equations of motion in the core volume under macroscopic conditions on the effective surface are obtained. Within the framework of this approach, a simple solution to some problems of collective nuclear dynamics has been obtained. The characteristics of isoscalar and isovector resonances in spherical and deformed nuclei are studied. Excitation energies, transition densities, energy-weighted sum rule distributions, and collisional widths are obtained.

The works of V. M. Strutinsky are among the most significant studies in the theory of atomic nuclei. Both the works themselves and the numerous experimental studies associated with them were discussed at many international conferences. Several conferences were specially devoted to the study of new aspects of the nuclear fission process arising from the theory of V. M. Strutinsky.

Articles by V. M. Strutinsky “Shell effects in masses of nuclei and strain energies” (1967) and “Shells in deformed nuclei” (1968) are recognized as one of the most quoted ones and evaluated by the US Institute of Scientific Information as “classical quoting”.

The expressions “Strutinsky’s energy theorem”, “Strutinsky’s shell corrections method”, and “Strutinsky’s two-humped barrier of fission” are widely included in the world scientific literature on nuclear theory and nuclear physics.

The phenomenon of the existence of a shell structure in strongly deformed nuclei predicted by V. M. Strutinsky and the formation of a metastable intermediate state in the process of fission are registered as a discovery in the USSR ( State Register of Scientific Discoveries of the USSR No. 200, 1977).

The works of V. M. Strutinsky received legal recognition and are widely known in our country and abroad. Many results, first obtained by him, played an important role in the development of modern concepts of the theory of complex atomic nuclei; they are included in basic courses in nuclear physics. He trained a large number of specialists, many of his students became candidates and doctors of sciences, professors. Deep scientific intuition, professional skills of a theoretical physicist, sharp criticism in work and a sensitive attitude towards people, a keen interest in everything new in science and life, integrity and uncompromisingness created V.M.Strutinsky a high authority among domestic and foreign scientists.

Merit

Medals " For Labor Valor " (1983) and " In memory of the 1500th anniversary of the city of Kiev ."
Laureate of the scientific prize of the A. von Humboldt Foundation (1991).
Prize in Nuclear Physics. T. Bonner of the American Physical Society (1978) for research in the theory of shell structure, nuclear fission, and stability of heavy and superheavy nuclei).
Title of Honorary Doctor of Science at the University of Copenhagen (1979) at the proposal of the Institute. Niels Bohr ( Denmark ) in connection with the 500th anniversary of the University of Copenhagen ).

Key dates of life and work

Chronology

date	Event
October 16, 1929	Date of birth of Vilen Mitrofanovich Strutinsky
1947	He graduated from high school in Odessa
1947-1951	Student of the Faculty of Physics and Mathematics of Odessa State University
1951	Transferred to the V course of the Faculty of Physics and Mathematics of Kharkov State University
1952	He graduated with honors from Kharkov State University with a degree in Theoretical Physics
1953-1970	Works in the Department of Nuclear Theory of the Institute of Atomic Energy named after I.V. Kurchatova (Moscow), as a senior laboratory assistant (1953-1954), junior research fellow (1954-1956), research fellow (1956-1961), senior research fellow (1961-1970)
1957-1958	Internship at the Institute of Theoretical Physics. Niels Bohr (Copenhagen, Denmark)
1959	He defended his thesis at the Moscow Engineering Physics Institute
1965	He defended his doctoral dissertation at the Joint Institute for Nuclear Research (Dubna)
1967-1970	He works at the Institute of Theoretical Physics. Niels Bohr (Copenhagen, Denmark) as a visiting professor
1970-1993	He works at the INR National Academy of Sciences of Ukraine (Kiev) as the head of the Department of Nuclear Theory (1970-1991), the chief scientific associate of the Department of Nuclear Theory (1992-1993)
1972	Elected Corresponding Member of the Academy of Sciences of the Ukrainian SSR
1977	The phenomenon of the formation of severely deformed heavy nuclei in a quasistationary state discovered by V. M. Strutinsky is included in the State Register of Scientific Discoveries of the USSR (No. 200, 1977)
1978	Awarded the Prize in Nuclear Physics. T. Bonner of the American Physical Society
1979	Awarded the title of Honorary Doctor of Science at the University of Copenhagen
1983	He was awarded the USSR medal "For Labor Valor".
1991	Elected member of the European Academy of Sciences and Arts (Trieste, Italy)
1991	Laureate of a scientific prize of the A. von Humboldt Foundation and guest professor at the Department of Nuclear Theory at the Technical University (Munich, Germany)
1992-1993	Visiting Professor at the National Center for Nuclear Physics (Catania, Italy)
June 28, 1993	Vilen Mitrofanovich Strutinsky died in Rome during a trip from Catania to Greece to attend the International Conference on Nuclear Physics.

List of Scientific Papers