Skobeltsyn Institute of Nuclear Physics
Lomonosov Moscow State University

Laboratory of nuclear and spectroscopic methods

The Laboratory of nuclear and spectroscopic methods (LNSM) was founded in 2013 from the Department of nuclear and spectroscopic methods which in turn originated from the Labratory of nuclear spectroscopy. The Head of the Laboratory is PhD. Irina Romashkina.

The studies of electon-nuclear interactions in the solid state by means of three methods: Mossbauer effect method, method of perturbated angular correlations of nuclear radiation and method of low-temperature nuclear orientation - provided a basis for the Laboratory's activity. These methods were developed by one of the founders of Mossbauer spectroscopy in the Soviet Union, the Head of the Laboratory in 1951-1986 Vladimir SHpinel.

Currently the scientists of the Laboratory study complicated magnetic systems by means of Mossbauer nuclei as probes, which provide information about the structure and properties of crystals at the local level.

Phenomenon of temporal self-organizing in the crystals under influence of electric shock, gamma-emission or external pressure were studied by means of Mossbauer effect method. A new approach to the problem of collective excitation of Mossbauer nuclei is developed.

A unique remote access Mossbauer spectrometer is developed and manufactured.

Magnetic structure of metallic systems with competing change interactions (magnetic iron allys with transition metals, intermetallides of rare earth elements and uranium) are studied by means of Mossbauer effect. New information about the influence of change interactions on the type of magnetic ordering and on the phase changes and new data on magneto-elestic interactions in the binary iron alloy were obtained.

Development of the method of perturbated angular correlations (PAC) provided a basis for the studies of local electronical and magnetic properties of the substances under conditions of extremal compression. The scientists of the Laboratory in cooperation with colleagues from the Institute of High-Pressure Physics RAS, Joint Institute of Nuclear Research and Institute of Physics of M. Curie-Sklodowska University (20-031 Lublin, Poland) have shown that PAC method can be used for determination of change of ytterbium ions valency in the intermetallic compounds depending on pressure and for studies of quarupole phase changes in the compaunds with cubic structure.

One of the directions of the Laboratory's activity is studies of the physical basis of the operation of soft X-ray and gamma-detectors based on superconductive tunneling transitions, which need low temperature. A computerized instruments complex for registration of current-voltage characteristics of tunneling transitions, signal shape and amplitude spectra produced during radiation quants absorption within wide temperature range from helium to milli-degrees was developed. It was found that energy resolution of niobium-based detectors is better, than up-to-date semiconductor detectors. Investigations of tantalum-based detectors was started.

A group of theorists consisted of Leonid Blokhintsev, Yuri Orlov, Dmitry Savin is specialized in application of analytical methods for the theory of nuclear reactions and the theory of several particles nuclear systems. Astrophysical nuclear reactions are under investigation. Special attention is paid to the sequent and effective recording of Coulomb effects which significantly change the properties of nuclear processes amplitudes and their behaviour at low energy.

Another group of theorists consisted of Grigory Koreman, Vladimir Popov, Sergey Yudin is specialized in the exotic atoms theory, including muons and hadrons (pions, kaons, antiprotons). Properties of these atoms and processes with their participation are discussed. Specific attention is paid to such processes as QCD performance in hadron atoms, Lamb shift in muon atoms, etc., which influence significantly on the possibility of carrying out experiments on precised measurements of muon and hadron atoms characteristics, which in turn is associated with the problems of fundamental symmetry and interaction.

During the last five years the scientists under the leadership of Grigory Korenman developed a model of collisional transitions between the sub-levels of super-fine structure of anti-proton helium atom, calculated collisional transitions and spread of M1-transitions, analyzed kinetics of the transitions between the conditions of super-fine structure in anti-proton helium basing on the method of generalized quantum kinetics equation, which allows simultaneous taking into account influence of collisional processes and of external micro-wave emission. Cross-sections of elastic scattering, Stark and Coulomb transitions of the excited muon and pion hydrogen atoms were calculated, dynamics of the lightest hadron atoms in the medium at low temperature was analyzed. The projects on RFBR grants and joint RFBR-Austrian scientific foundation were executed.

The scientists of the Laboratory cooperate with colleagues from the Joint Institute of Nuclear Research (Dubna, Russia), Institute of High-Pressure Physics RAS (Troitsk, Russia), Kotelnikov Institute of Radioelectronics RAS (Moscow, Russia), Texas A&M University (Texas, USA), Istituto Nazionale di Fisica Nucleare (Fraskati, Italy), Laboratore Nazionale del Sud (Katanya, Italy), Institute of Nuclear Physics (Tashkent, Uzbekistan), Institute of Physics of M. Curie-Sklodowska University (Lyublin, Poland), Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Science (Vienna, Austria), University of Tokyo (Tokyo, Japan), Japan Institute for Physical and Chemical Research (RIKEN), Universita di Brescia (Italy).

A conference "Mossbauer Spectroscopy and Its Applications" is organized starting from 1985. The latest ICMSA-12 happened in 2012.