Iamze Kalandadze

Studding multipoles of g-radiation and determination of share of admixture in the case of mixed g-transition is necessary to study the physical properties of the excited levels of nuclei and to verify different theoretical nuclear models. It is also important to investigate the forms of conversion lines and determine their half-widths. Accumulated quantitative materials give possibility to receive new information about nuclei and atomic levels. In the paper, the results of investigations of internal conversion electron (ICE) spectrum of 169Tm 93.61 keV g-transition are presented. Measurements were carried out by means of magnetic beta-spectrometer with 0.04 % high resolution. Forms of L I, L II, and L III conversion lines are studied and relative amounts of their expansions are measured. Mean quantity of d 2 from the established internal conversion coefficients (ICC) are calculated d 2 = 0.034 ± 0.003. Average significance of the share of electric quadrupole admixture a = 3.3 ± 0.3 % are found, which corresponds to M1+3.3%E2 mixed -transition.

New model of disordered regions in irradiated single-crystalline silicon is develope based on measurements of electrophysical parameters temperature-dependences in n-Si:P and p-Si:B samples irradiated at room temperature with high-energy protons and electrons, respectively, and isochronously annealed at various temperatures. Disordered regions are imagined as relatively high-conductive inclusions with increased concentration of radiation defects separated by Ohmic interfaces with relatively lowconductive matrix. Initially, these regions are electrically neutral, but depending on the annealing mode the constituting radiation defects can change their charge-states.

During the last sixty years are intensively investigated the materials RE1-x AxMnO3 (RE – Pr, Nd, Sm; A – Ca, Ba, Sr. and et. al.) due to its colossal magnetoresistance (CMR) effect, which are observed in the range of 0<x<1 concentrations, where the ferromagnetic phase is appearing.  The Sr-doped samples of Sm1-xSrxMnO (0.25°x°0.45) were prepared by the solid-state reaction method. Desired ratios of the mixture of Sm2O3, SrCO3 and Mn metal powder were pelletized and were heated at 1100°C for 7 days in air into the muffle furnace (KSL-1100X-S, MTI corporation, temperature accuracy ±1oC). After grinding the received products were pressed as pallet under a pressure of 200 MPa by hydromatic press (Holzmann-maschinen, Type: WP 10H). The pallets were heated again at the same temperature for 7 days in air and then were slowly cooled to room temperature. Obtained specimens were identified by X-ray diffractometer (XRD, Dron-3M) with CuKa radiation.

Measurements of linear susceptibility were carried out in the case, when collinear constant and variable fields H(t)=H+hcos(wt) were applied to the sample. High harmonics measurements errors were ~ 2%, when the measured signal was less, than 0.2 μV. However, the error does not exceed 0.5% for higher amplitudes. The phase method was used to study the real parts of the linear susceptibility. The errors in the determination of susceptibility at the higher frequencies, than 1 kHz do not exceed 1%.

With the aim to generate a nano-dimentional atom clusters by the irradiative method, the influence of irradiation by the particles of various energies and types on the nature of radiation induced defects originated in n-Si crystals has been investigated in the work. For the investigation we used the n-type Si crystals with the electron concentration 6.10^13 cm^(-3). We irradiated the crystals in size of 1´3´10 mm at 300K temperature by the electrons with the energy of 2 and 8 Mev. The difinite part of the samples we have irradiate by the protons with the energy of 25 Mev. The method of isochronal baking is used. We oerformed the baking within the interval of 80-600oC within the temperature interval by step of 10oC. 10 minutes are defined for time baking. After each cycle of baking the pecific resistivity of the samples has been measured by means of two probe methods, and the concentration of electrons were measured within the temperature interval 77-300 K. By means of these data we were calculating the Hoall mobility. The photo-Hall method has been applied in the work.

Doctoral Thesis Referee

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Scientific editor of monographs in foreign languages

Scientific editor of a monograph in Georgian

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Member of the editorial board of a peer-reviewed scientific or professional journal / proceedings

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