Laboratory of nuclear gamma-resonance spectroscopy
In accordance with the decision of the 8th All-Union Coordination Meeting on Research Reactors (Alma-Ata, 1974) at the Institute of Nuclear Physics at the WWR-K neutron diffraction studies had to be deployed for the tasks of radiation material science. Zhetbayev A. K, who at that time used to be the Institute’s Scientific Secretary and head of the nuclear gamma-resonance spectroscopy group, was entrusted to create such a laboratory. The neutron diffraction researching laboratory got organized in the summer of 1975. It got composed of six members of Zhetbayev’s group. By 1979, the laboratory has replenished with new people and their number reached 17 employees. On the extracted neutron beams from nuclear reactor the apparatus got mounted for slow neutrons diffraction researches, as well as the apparatus of the neutron radiography «AGAVA».
By the end of the 70s the scientific and experimental base had been fully formed in the laboratory, composed of neutron diffraction and neutron radiography installations, 5 Mössbauer spectrometers and additional equipment that allowed to conduct experiments in a wide temperature range (from 4 to 2500 K) in inert, redox atmosphere, or in high vacuum conditions. In connection with the suspensions of the nuclear reactor work at the end of 80s, in 1991 the laboratory got renamed into the laboratory of nuclear gamma-resonance spectroscopy.
The first successful experiment on the observation of the Mössbauer effect in Kazakhstan was carried by Zhetbaev A. K. in the summer of 1964 on the isotope 182W with a source 182Ta, activated in the reactor of the Nuclear Physics Institute of the Academy of Sciences of the Uzbek SSR in Tashkent, at the facility with a mechanical system of the Doppler shift of the gamma rays.
At the same time the apparatus was created with the electrodynamic system of source movement and its electronic equipment. The technique of producing isotope 57Co at the Ural (Sverdlovsk) Polytechnic Institute’s cyclotron was being mastered.
With the commissioning of the new apparatus the intensive study of the chemical compounds of iron and geological origin began.
In those years, the laboratory staff made a number of methodological developments, which allowed the team to earn international recognition:
- Method of selective gamma-resonance spectrum registration of the nuclear reaction products for selective sensing of microscopic (on a atomic scale) areas of atom inhibition in solids
- Manufacturing technology of Mössbauer 6.25 keV radiation sources, emitted during the 181W nuclear disintegration, and resonance absorbers of tantalum metal (for the first time in the USSR). The observation of the Mössbauer effect on tantalum-181 possessing hypersensitivity to any changes in internal fields at the nuclei
- Mössbauer spectrometer with a magnetic energy analyzer of conversion and secondary electrons, and position-sensitive detector for sensing near-surface layers of the object under study
With the support of the international organization IUPAC (International Union of Pure and Applied Chemistry) in Alma-Ata from September 26 to October 1, 1983 The International Conference on Applications of the Mössbauer Effect (ICAME-83) was held. Decision to determine Alma-Ata as the conference venue was made possible due to the “… great successes of Kazakhstan scientists in the field of radiation physics and solid state physics, metallurgy and chemistry with Mössbauer effect application …” (the decree of the Presidium of the USSR Academy of Sciences)
Laboratory staff on the celebration of its fifth anniversary
The provided photos show some working points and conference meetings, which obtained its active participant and the discoverer himself, Nobel Prize Laureate in Physics 1961, Rudolf Mössbauer. Over the years of its existence laboratory staff produced two doctorates (Zhetbayev А.К., Donbayev К.М.) and twelve PhD theses (Verezhak М.F., Livertc Е.Z., Dosmagambetov Т., Ozernoi А.N., Shokanov А.К., Zhantikin Т.М., Donbayev К.М., Serikbayeva Z.Т., Mukusheva М.К., Kerimov E.А., Zhubayev А.К., Suslov Е.Е).
Over the past decade the laboratory got retooled with new experimental equipment. Laboratory space got renovated in accordance with European standards and all the conditions got created for carrying out scientific and research work on the highest experimental level.
The laboratory has two modern spectrometers, that allow to carry out research using methods of nuclear gamma-resonance spectroscopy in the “transmissive” geometry – with the registration of gamma rays in the temperature range from room temperature to liquid nitrogen temperatures, and in the backscatter geometry – with the registration of internal conversion electrons. The main experimental laboratory equipment can ben seen on the following photos:
The experimental Mössbauer spectra is performed using software packages MS Tools and SpectrRelax, that allow to solve the following tasks:
- increasing the resolution and effective noise reduction in the spectrum;
- model decoding of the Mössbauer spectra using a priori information on the experiement conditions and the subject under study
- restoration of the distribution functions of hyperfine parameters of partial spectra;
- qualitative and quantitative phase analysis using spectra of standard specimens
Based on research findings during the period from 2008 to 2011 the Laboratory of Nuclear Gamma-Resonance Spectroscopy staff has published over 30 articles in leading national and international journals.
Highly qualified specialists in solid state physics are being trained. In the laboratory pre-diploma practice periodically take place and on the basis of performed work the diploma projects are being defended by Satbayev Kazakh National Technical University students, as well as by L.N. Gumilyov Eurasian National University and Al-Farabi Kazakh National University students. For them in 2010 on the Institute of Nuclear Physics base the School-Seminar “Modern applications of the Mössbauer spectroscopy” was organized and successfully conducted, during which in front of students the leading global specialists, Professor Rusakov V.S. (Russia), Professor Nagy D. (Hungary), and Miglerini M. (Slovakia), gave presentations with lectures on topical themes of nuclear gamma-resonance spectroscopy.
Laboratory’s main scientific results (1975-2012)
- A method for registering primary knocked-on atoms and their final state is introduced, which allowed to expand the application of the nuclear gamma-resonance spectroscopy on objects which do not possess a Mössbauer element in their initial state. This method is incorporated in a scientific and research program “Amorphous materials” SPA “Red Star”.
- The cementite state in compositionally different Fe-C and Fe-Al-C alloys depending on irradiation. Determined the conditions and proposed the cementite decomposition mechanism under irradiation, studied the kinetics of phase and chemical transformations in the oxides and mixed oxides of iron.
- Developed methods of calculating electric-field gradient (EFG) on 57Fe nuclei. Derived formulas that simplify the calculations of lattice sums. Developed the technique for calculating EFG on three-valence iron nuclei with consideration of exchange effects in iron-oxygen complexes.
- For the first time mastered the measuring technique of angular correction of resonance-scattering g-rays 14,4 keV from 57Fe, which helped give the definition of the nature of the broadening of resonance lines of alloys and chemical iron compounds.
- For the first time studed the interaction between impurities with the radiation defects in niobium and molybdenum.
- Researched, at the atomic level, the mechanism of radiation-stimulated processes of ordering-disordering and phase transformations in alloys Fe, Mn, Ni, Al, and amorphous materials.
- For the first time in Soviet Union mastered the manufacturing technology of Mössbauer radiation sources 6,25 keV, emitted during the decay of the nucleus tungsten-181, and resonance absorbers from tantalum metal. Established the observation technique of Mössbauer effect on tantalum-181, which possesses a hypersensitivity to internal fields by nuclear parameters, hence why it appeared inaccessible to experimental observation.
- Developed the Mössbauer spectrometer with magnetic energy analyzer for conversion and secondary electrons and position-sensitive detectors for fiber sensing of nearsurface material layer.
- Provided the experimental justification for the concept of “thermal spikes” in various classes of solids: chemical compounds, metals, alloys and metal glasses.
- Described, at the atomic level, the interaction mechanisms and diffusion of point defects, the primary manifestations of phase formation and ordering-disordering under radiation.
- Found a new phenomenon of the radiation stabilization of ferrite’s magnetic parameteres
- Applied the neutron radiography into researches on the direct nuclear energy conversion to electrical. With the help of neutron radiography held the diagnostics of the thermionic converter state, that passed the resource endurance tests in the active reactor zone, which allowed to achieve a qualitatively new, previously unnaccessible results on thermionic converter work. In details, traced the process of the Ostwald ripening of cesium vapors in electrogenerating channel and its fuel redistribution
- For the first time in Soviet Union, synthesized the superconductor based on thallium with the highest transition temperature into the superconducting state: 125 K. The synthesis technology is transferred to Pyshminsky pilot plant “GIREDMET”.
- Perfected the manufacturing technology of Mössbauer sources 57Co(Rh), which allowed, for many years, to conduct Mössbauer researches with own sources.
- For the first time with the help of methods of Mössbauer spectroscopy on nuclei 57Fe with the attraction of X-ray and structural analysis, as well as methods of Rutherford backscattering of protons, it was possible to conduct the systematic researches of thermally induced diffusion and phase transformations in layered systems of iron-beryllium in a wide concentration range.
- Found the g-a-transformation in a stainless steel under beryllization, plastic strain, and irradiation. Established the mechanism of such transformations.
- For the first time conducted researches on thermally induced processes of diffusion and phase transformations in layered systems based on iron and aluminum. Established the kinetics of diffusion processes and phase transformations in such systems.
- For the first time conducted researches on thermally induced processes in layered systems of iron and titanium with the isochronous and isothermal annealing.
- Suggested an injection method of radioactive tagged atoms 57Co in nanoscaled protective metal coatings during their formation by electrolytic codeposition with the parent coating material.
- For the first time ferromagnet FeBe2 was observed in regards to its changes in magnetic properties after irradiation by helium and krypton ions, and their reset was observed after annealing at 650ºC temperature, which showed the possibility to control material’s magnetic properties by the impact of accelerated ion beams.
- The conducted tests of objects under study in regards to radiation resistance showed that in the operating-temperature range 600-650ºC the established system Be-Fe-Be remains to be both thermally- and radiation-resistant.
- Developed the radioactive sources 57Co(Сr) of high quality. They are required to conduct works in tandem with the resonance detector, which significantly reduces the Mössbauer experiment’s duration and considerably raises the resolution of the experimental apparatus
Currently, the laboratory staff, in the implementation of the scientific and technical program “Development of nuclear power in the Republic of Kazakhstan”, performs scientific research works on the theme “Researches on the creation of multilayer nanoscale metal coatings for applications in nuclear power engineering and industry”.
Chief of Laboratory Ozernoi A.N.