Publications

1. Arun S. Wagh, S.Yu. Sayenko, A.N. Dovbnya, V.A. Shkuropatenko, R.V. Tarasov, A.V. Rybka, A.A. Zakharchenko. Durability and shielding performance of borated Ceramicrete coatings in beta and gamma radiation fields // Journal of Nuclear Materials. 2015, vol. 462, pp. 165–172.

   Abstract Full text (PDF) Ceramicrete^TM, a chemically bonded phosphate ceramic, was developed for nuclear waste immobilization and nuclear radiation shielding. Ceramicrete products are fabricated by an acid–base reaction between magnesium oxide and mono potassium phosphate. Fillers are used to impart desired properties to the product. Ceramicrete’s tailored compositions have resulted in several commercial structural products, including corrosion- and fire-protection coatings. Their borated version, called Borobond^TM, has been studied for its neutron shielding capabilities and is being used in structures built for storage of nuclear materials. This investigation assesses the durability and shielding performance of borated Ceramicrete coatings when exposed to gamma and beta radiations to predict the composition needed for optimal shielding performance in a realistic nuclear radiation field. Investigations were conducted using experimental data coupled with predictive Monte Carlo computer model. The results show that it is possible to produce products for simultaneous shielding of all three types of nuclear radiations, viz., neutrons, gamma-, and beta-rays. Additionally, because sprayable Ceramicrete coatings exhibit excellent corrosion- and fire-protection characteristics on steel, this research also establishes an opportunity to produce thick coatings to enhance the shielding performance of corrosion and fire protection coatings for use in high radiation environment in nuclear industry.

2. L. Davydov, P. Fochuk, A. Zakharchenko, V. Kutny, A. Rybka, N. Kovalenko, S. Sulima, I. Terzin, A. Gerasimenko, M. Kosmyna, V. Sklyarchuk, O. Kopach, O. Panchuk, A. Pudov, A. E. Bolotnikov, and R. B. James. Improving and Characterizing the Quality of (Cd,Zn)Te Crystals for Detecting Gamma Radiation // IEEE Transactions of the Nuclear Science. 2015, vol. 62, no. 4, pp. 1779– 1784.

   Abstract Full text (PDF) Cd_0.9Zn_0.1Te ingots were synthesized from pure components (6N purity Cd, Zn, Te, with In as the dopant) and subsequently grown from the melt under an argon overpressure. Graphite crucibles (with and without an inner coating of pyrolytic BN) were used. The temperature gradient in the solidification zone was 7-30 K/cm, and the growth rate was 0.6-1 mm/hour. We investigated the chemical composition, structure, and electrical properties of the grown crystals, and established the relationships with their growth conditions. The bottom, middle, and top of the ingots had n-type conductivity, but slightly different properties. Resistivity reached a maximum in the middle of the ingots ((2.5-5)×10¹⁰ Ohm-cm), and was less at the edges ~0.8×10¹⁰ Ohm-cm. The value of the bandgap was minimal in the middle of the ingots (~1.5 eV), and 1.53-1.55 eV at the edges. The compensation degree (Nd/Na) of the energy level, responsible for the low dark conductivity, showed a maximum value at the bottom of the ingots (~60-90 %), and a minimum in the ingots’ middle part (1-2 %). The crystals were then used to fabricate Cd(Zn)Te detectors for gamma radiation.

3. V.A. Bilous, V.M. Borysenko, V.M. Voevodin, S.Yu. Didenko, M.І. Il’chenko, І.M. Neklyudov, О.V. Rybka. Dependence of the Radiation-Protective Efficiency of Al–Pb Multilayer Composites on Their Structure. Materials Science: Volume 50, Issue 4 (2015), Pages 600-603.

   Abstract Full text (PDF) We describe the methods and the results of the experiments with passing of monochromatic beams of electrons with an energy of 2.5 МеV through specimens of aluminum and Al–Pb layered composites with different internal architectures. It is shown that, as compared with aluminum, the investigated composites are characterized by a higher absorptivity. This enables us to reduce the weight of the radiation-protective structure with preservation of the efficiency of protection on the level of aluminum or increase the efficiency of protection preserving the constant weight of the entire structure.

4. Iu. Nasieka, V. Strelchuk, M. Boyko, V. Voevodin, A. Vierovkin, A. Rybka, V. Kutniy, S. Dudnik, V. Gritsina, O. Opalev, V. Strel’nitskij. Raman and photoluminescence characterization of diamond films for radiation detectors // Sensors and Actuators A: Physical. 2015, vol. 223, pp. 18–23.

   Abstract Full text (PDF) The structural quality of the diamond films (DF) deposited on a molybdenum (Mo) substrate seeded with micron-sizes diamond crystals and on unseeded one were characterized using micro-Raman (μ-RS) and photoluminescence (PL) spectroscopy. It was found that first-order μ-RS spectra of both films consist of three main peaks with the frequencies 1337 cm⁻¹, 1393 cm⁻¹ and 1569 cm⁻¹. The mentioned peaks are attributed to the diamond vibration mode T2g in the center of the Brillouin zone, the vibration modes D(A1g) and G(E2g) of the disordered graphite structure and the crystalline one, respectively. The intensity of the diamond related line in the spectrum of DF on the seeded substrate is much smaller and the peak is wider (11.5 cm⁻¹) relative to the natural diamond (2 cm⁻¹); the peak is somewhat smaller and wider relative to the DF on the unseeded substrate (10 cm⁻¹). Such features in the μ-RS spectra of both films indicate that the process of the substrate seeding with the diamond crystal seed leads to the synthesis of DF with a relatively small defect density and with a more homogeneous distribution of the residual strains. In the PL spectra, the lines caused by the recombination centers with the participation of the nitrogen impurity atoms are prevailing. The defects of the dominating type are the nitrogen-vacancy complexes [N-V] ⁰ and [N-V] ⁻. The intensities of the nitrogen complex related lines in the PL spectra of DF on the seeded substrate are smaller, which indicates smaller defects concentration than in the DF on the unseeded one. From the analysis of the μ-RS and PL data, we summarize that seeding of the substrate with diamond crystals leads to the improving of the crystalline perfection. However, the electrical measurements and the analysis of the performance of the detectors based on the DFs, show that DFs on the unseeded substrate have higher suitability for the detectors manufacturing.

5. Iu. Nasieka, V. Strelchuk, M. Boyko, A. Rybka, V. Kutniy, D. Nakonechnyj. The comprehensive evaluation of the structural and functional properties of the gas-statically treated Au–CdZnTe–Au structures for X- and gamma-ray detectors // Radiation Physics and Chemistry. 2015, vol. 113, pp. 47–52.

   Abstract Full text (PDF) The influence of the gas-static processing on the optical, structural and electrophysical properties of Au–CdZnTe–Au structures, used in X- and gamma-ray detectors, was investigated. The processing, which is described in detail in the experimental part, was done in a laboratory-scale setup “GAUS-4/2000-35” with the following process parameters: pressure = 0.32±0.02 GPa, temperature ~170°C, time=2 h. The influence of the mentioned processing on the photoluminescence, the Raman scattering, the electric resistance, the I–V characteristics and the spectrometric parameters of the Au–CdZnTe–Au structures was determined. The physical mechanisms, through which the gas-static processing induces changes in the structural and functional properties, were analyzed. It was observed that the gas-static processing (with the above-mentioned process parameters) of the Au–CdZnTe–Au structures leads to a significant increase of the electric resistance of the structures; it also leads to the increase of the intensity of the photoelectric absorption peak when the respective detector is registering X- and gamma-radiation with energy near 32.19 keV. The Raman and photoluminescence data indicates the formation of the surface oxides TeO_x and the compensation of Cd vacancies by Au atoms. The assumption that, under the discussed processing, two different rival processes modify the Au–CdZnTe junction due to the influence of the increased temperature ~170°C and pressure ~0.3 GPa, was suggested. The first process is the formation of TeO₂ oxide (which increases the electric resistance) on the contact; the second process is the destruction of the surface films of the oxides and the absorbed gases. Most likely, the first process is dominant, which was evidenced by the Raman and photoluminescence measurements.

6. A.B. Batrakov, E.G. Glushko, А.М. Yegorov, А.А. Zinchenko, Yu.F. Lonin, А.G. Ponomaryov, A.V. Rybka, S.I. Fedotov,V.T. Uvarov. Study of hard X-ray bremsstrahlung at the radiation-beam complex “TEMP” // Problems of Atomic Science and Technology (PAST). Nuclear Physics Investigations, 2015, issue 6(65), pp. 100-104.

   Abstract Full text (PDF) Basic parameters of the hard bremsstrahlung radiation were calculated for the microsecond accelerator of relativistic electronic beams “TEMP”. Optimization of converters is conducted for these aims. Maximal doses of bremsstrahlung radiation are experimentally got at beam-radiation complex “TEMP”. The diagrams of orientation of the bremsstrahlung radiation are taken depending on energy of beam and form of electrodes.

7. V. Bilous, V. Borysenko, V. Voyevodin, S. Didenko, M. Ilchenko, O. Rybka, O. Kuznetsov, and Y. Plisak. Layered Metal Composites: Newest Generation of Radiation-Protective Materials // Journal of Materials Science and Chemical Engineering. 2014, vol. 2, pp. 6-11.

   Abstract Full text (PDF) The expediency of development of one of the newest highly effective radiation-protective materials — layered composites of “light metal/heavy metal” type is substantiated. The characteristics of the internal architecture of composites of Al/Pb type made by consecutive application of vacuum and normal atmospheric rolling are adduced. The differences between the radioisotope and accelerating techniques of experimental testing of radiation-protective properties of materials are described. The results of the testing of composites and the influence of their structure on radiation-protective properties of the investigated materials are characterized. It is shown that the radiation-protective efficiency of composites certain structures may be 30% - 40% higher than the aluminum. This gives the opportunity to reduce the weight of radiation-protective structure at preservation of effectiveness of protection at aluminum level, or to increase the effectiveness of protection at constant weight of this structure.

8. R.M. Muratov, A.A. Vierovkin, V.E. Kutny, Yr.N. Nezovibatko, A.V Rybka, V.S. Taran. Development and application of metal contacts on polycrystalline diamond films using combination of HF and ARC plasma sources // Problems of atomic science and technology (PAST). Plasma Physics. 2014, issue 6 (94), pp. 233-236.

   Abstract Full text (PDF) In this paper, the technology of application of ohmic contacts using arc discharge assisted by HF field was developed for semiconductor radiation detectors production. Polycrystalline diamond material for production of detectors was synthesized by chemical vapor deposition method (CVD) in NSC KIPT. Bilayer contacts were deposited on polycrystalline CVD (pCVD) diamond films, where the first layer was chromium, and the second layer – copper or stainless steel respectively. Electro-physical characteristics of pCVD diamond detectors with different contact materials were studied.

9. A.A. Zakharchenko, A.V. Rybka, L.N. Davydov, A.A. Vierovkin, V.E. Kutny, M.A. Khazhmuradov. Monte-Carlo Simulation of Response of CdZnTe Detectors of Beta-radiation // East Eur. J. Phys. 2014, vol.1, no.3, pp. 68-73.

   Abstract Full text (PDF) Response functions of CdZnTe detector, developed for measurement of electron energy spectra, are investigated. The experimental response of CdZnTe detector is compared to the spectra simulated by Monte-Carlo method. A satisfactory agreement of simulated and experimental data is reached with introduction in the theoretical detector model of two fitting parameters – products of mobilities and lifetimes of electrons and holes. It is shown that the main disagreement of experimental and simulated spectra is connected to the high level of noise in the preliminary amplifier.

10. A.A. Zakharchenko, L.N. Davydov, A.I. Skrypnyk, A.V. Rybka, V.E. Kutny, M.A. Khazhmuradov, P.M. Fochuk, V.M. Sklyarchuk, A E. Bolotnikov, R. B. James. Spectroscopic response of Cd(Zn)Te radiation detectors with a Schottky diode // Proc. SPIE, Vol. 9213, Paper 92131C, 2014.

    Abstract Full text (PDF) We investigated the spectroscopic properties of several Cd(Zn)Te detectors with a Schottky contact and simulated them via a computer code. The responses were determined of 0.5-mm-thick surface-barrier Ni/Cd(Zn)Te/Ni detectors to gamma-rays from reference sources of ²⁴¹Am, ¹³³Ba, ¹⁵²Eu, ¹³⁷Cs and ⁶⁰Co. The best measured energy-resolution at 661.67 keV (¹³⁷Cs) of these detectors under 800 V of displacement voltage was better than 1.5%. The detectors’ response functions, simulated with Geant4 toolkit, agreed satisfactorily with our experimental data.

11. V. Sklyarchuk, P. Fochuk, I. Rarenko, Z. Zakharuk, O. Sklyarchuk, Ye. Nykoniuk, A. Rybka, V. Kutny, A. E. Bolotnikov, and R. B. James. Mechanisms of the passage of dark currents through Cd(Zn)Te semi-insulating crystals // SPIE, Vol. 9213, Paper 92131G-10, 2014.

    Abstract Full text (PDF) We investigated the passage of dark currents through semi-insulating crystals of Cd(Zn)Te with weak n-type conductivity that are used widely as detectors of ionizing radiation. The crystals were grown from a tellurium solution melt at 800°C by the zone-melting method, in which a polycrystalline rod in a quartz ampoule was moved through a zone heater at a rate of 2 mm per day. The synthesis of the rod was carried out at ~1150°C. We determined the important electro-physical parameters of this semiconductor, using techniques based on a parallel study of the temperature dependence of current-voltage characteristics in both the ohmic and the space-charge-limited current regions. We established in these crystals the relationship between the energy levels and the concentrations of deep-level impurity states, responsible for dark conductivity and their usefulness as detectors.

12. A.A. Zakharchenko, , A.I. Skrypnyk, M.A. Khazhmuradov, A.V. Rybka, V.E. Kutny, P.M. Fochuk, V.M. Sklyarchuk, A.E. Bolotnikov, and R.B. James. The energy dependence of the sensitivity for planar CdZnTe gamma-ray detectors // Proc. SPIE, Vol. 8852, Paper 88521B, 2013.

    Abstract Full text (PDF) Considerable variations in the charge-carrier transport parameters necessitate individual calibration of CdZnTe gamma-ray detectors for many applications. We carried out a set of experiments wherein we determined that the main region of interest for the energy dependence of CdZnTe-detectors’ sensitivity lay in the gamma-quantum energy range of 0.03 to 3 MeV. This finding was satisfactorily verified and reconstructed from our measurements of pulse-height distributions using ²⁴¹Am-, ¹³⁷Cs-, and ⁶⁰Co-sources. We discuss our comparison of the quality-of-fit of the approximation formulae with our detailed calculations of the sensitivity of CdZnTe detectors via a Monte-Carlo method.

13. V. Sklyarchuk, P. Fochuk, Z. Zakharuk, R. Grill, V. Kutny, A. Rybka, D. Nakonechny, A. Zakharchenko, Ye. Nykoniuk, A. E. Bolotnikov, and R. B. James. Effect of side-surface passivation on the electrical properties of metal-Cd(Zn)Te-metal structures // Proc. SPIE, Vol. 8852, Paper 88521I, 2013.

    Abstract Full text (PDF) We explored the influence of Cd(Zn)Te detectors on the detector’s dark current for different methods of contact formation and passivation of the side surfaces. Our findings suggest that the dark current of a homogeneous detector with ohmic contacts is limited by the detector’s resistivity and the operating voltage. Detectors with a rectifying barrier have a markedly lower dark current at the same voltage and contact geometry than those without such a barrier, and their sides have a larger space charge than those of untreated ones. The major factor lowering the detector’s dark current is the formation of a rectifying barrier that occurs while creating contacts to the detector; the role of passivation of the lateral surface in this case is minimal. However, passivation plays the main role in the formation of leakage current in homogeneous detectors with ohmic contacts, where the uniformity of the electric field is important inside the detector, or in other studies used for determining the bulk resistivity of the detector material. We formed a surface-barrier structure on a semi-insulating Cr-Cd(Zn)Te-Cr crystal (n-type) with a resistivity of 10¹⁰Ohm·cm at room temperature. The measured leakage current of this detector was less than 3 nA at 1500 V. We discuss our findings on this detector’s structural properties.

14. Iu. Nasieka, N. Kovalenko, V. Kutniy, A. Rybka, D. Nakonechnyj, S. Sulima, V. Strelchuk. Photoluminescence-based material quality diagnostics in the manufacturing of CdZnTe ionizing radiation sensors. Sensors and Actuators, vol. A 203, pp. 176-180, 2013.

    Abstract Full text (PDF) A photoluminescence method was used for characterization of crystalline perfection of CdZnTe single crystals in the different stages of an up-to-date process of ionizing radiation sensor production. It was shown that the point method is an effective tool for diagnostics of technology-induced defects and structural irregularities, which can have substantial effect on the sensor performance. From the photoluminescence spectrum, one can obtain information about nature and relative concentrations of initial (as-grown) and technology-induced defects as well as about their interaction. Therefore, the photoluminescence method gives the possibility to correct technological regimes and thus support high quality of the material and high spectrometric (energy resolution, sensitivity) performance of sensor devices.

15. A. Zakharchenko, A. Rybka, V. Kutny, A. Skrypnyk, M. Khazhmuradov, P. Fochuk, A. E. Bolotnikov, R. B. James. Transport properties and spectrometric performances of CdZnTe gamma-ray detectors // Proc. SPIE, Vol. 8507, Paper 85071I, 2012.

    Abstract Full text (PDF) We investigated the influence of the ratio of the electron and hole mobility-lifetime products, (μτ)_e,h and (μτ)_e/(μτ)_h, on the resolution of CdZnTe planar radiation detectors via Monte-Carlo simulations. Preliminary results show that this ratio exercises a larger effect than that of any other parameter on the detector’s peak-to-valley ratio and resolution. We determined the range of values of the ratio (μτ)_e/(μτ)_h where the fast degeneration of the photopeak in CdZnTe detectors takes place at a gamma-ray energy 661.7 keV (¹³⁷Cs). We offer an explanation, based on the results of some of our experimental data, on the spectrometric performance of CdZnTe detectors.

16. L.N. Davydov, A.V Rybka, A.A. Vierovkin, S.F. Dudnik, V.I. Gritsyna, V.E. Kutny, O.A. Opalev, V.A. Shevchenko, I.N. Shlyahov, V.E. Strelnitsky, A.Eh. Tenishev, V.L. Uvarov, R.B. James, A.E. Bolotnikov, P.M. Fochuk. Registration of high-intensity Electron and X-ray fields with polycrystalline CVD diamond detectors // Proc. SPIE, Vol. 8507, Paper 85071N-1, 2012.

    Abstract Full text (PDF) We developed radiation-hard diamond detectors for registering intense fields of high energy electrons and X-rays, and monitoring the mode of operation of electron accelerators. After synthesizing a diamond film of detection quality up to 350-microns thick by chemical vapor deposition (CVD), we analyzed it by infra-red spectroscopy. We also developed techniques for heat treatment of the film, chemical etching, substrate removal, contact application, and priming by an exposure to X-rays and electrons. This work supported the production of detectors with a specific resistance of 10¹⁴ Ohm×cm. The dependence of the detector signal’s amplitude on the displacement voltage was investigated under exposure to a direct electron beam with a current ranging from 660 to 930 mA. The duration of the leading edge of a detector pulse was 5 μs. Experiments also were undertaken on the registration by diamond detectors of Bremsstrahlung radiation with an end-point energy of 9 to 70 MeV. We also evaluated the dependence of the amplitude of the detector’s signal on the displacement voltage. Our comparison of detectors’ physical properties and detectors’ response to alpha-particle irradiation before and after the exposure to the accelerator beam showed no degradation, even after the absorbed dose exceeded 11.5 MGy.

17. I.A. Sokolov, M.A. Bryushinin, V.V. Kulikov, A.S. Abyzov, L.N. Davydov, V.E. Kutny, A.V. Rybka, V.V. Slezov. Characterization of CdTe, Cd_xZn_1−xTe and GaAs detectors // Nucl. Instr. & Meth. A, 2009, vol. 610, no. 1, pp.298-301.

    Abstract Full text (PDF) We report space-and-time current spectroscopy for characterization of high-quality GaAs thin films grown on semi-insulating gallium arsenide substrates. The approach is based on illumination of semiconductor material with an oscillating interference pattern formed of two light waves, one of which is phase modulated with frequency ω. The non-steady-state photocurrent flowing through the short-circuited semiconductor is the measurable quantity in this technique. The alternating current resulted from the periodic relative shifts of the photoconductivity and space charge electric field gratings arising in the crystal's volume under illumination. The results of measurements of semiconductor material's parameters of CdTe and Cd_xZn_1−xTe detectors are presented. The experiments are carried out for the diffusion regime of signal excitation at light wavelength λ = 1.15 μm. The sign, conductivity and diffusion length are estimated from the dependencies of the signal on the temporal and spatial frequencies. The high-quality GaAs thin films grown on semi-insulating gallium arsenide substrates are characterized. The experiments are carried out in the geometry of the Michelson interferometer at the illumination wavelength of 532 nm. The dependence of the non-steady-state photocurrent on spatial frequency of the interference pattern is measured, allowing estimation of the diffusion length of photoelectrons in GaAs thin film L_D = 40 μm.

18. A.V. Rybka, L.N. Davydov, I.N. Shlyakhov, V.E. Kutny, I.M. Prokhoretz, D.V. Kutny, A.N. Orobinsky. Gamma-radiation dosimetry with semiconductor CdTe and CdZnTe detectors // Nucl. Instr. & Meth. A, 2004, vol. 531, pp.147-156.

    Abstract Full text (PDF) Problems related to the dosimetry of γ-radiation, in particular of high intensity, are investigated together with operational performances of detectors, their temperature stability, reproducibility and reliability of detector measurements. A comprehensive study was carried out of CdTe detectors, obtained by the Bridgman growth method, and CdZnTe detectors, crystallized by the Bridgman method at high pressure of inert gas. All the investigated ingots were of p-type conductivity. The current-voltage characteristics and dynamic resistance of detectors from CdTe and CdZnTe were measured over a wide range of operational temperatures (−30 to +70°C) and bias voltages (−300… +300 V). The dosimetry performance of CdTe and CdZnTe γ-radiation detectors was tested with standard calibration dosimetry rigs of different intensity. The relation between the detector count rate (count mode of operation) or detector anode current (integrated, or current mode of operation) and the exposure dose rate (EDR) of the γ-radiation was established. The count rate of the radiation registered from different sources (²⁴¹Am, ¹³⁷Cs, ⁶⁰Co) in the count mode depends linearly on EDR in the EDR range from 10 μR/h up to 1 R/h. In high-intensity radiation fields a measurement of the current induced by the γ-radiation, i.e. with the detector operating in "current mode", is preferable. In this case, our researches have shown that the EDR dependence of the output voltage of the current-voltage converter is linear in the range from 20 R/h up to 5000 R/h. Several designs of "detector-absorbing filter" sets were proposed for the correction of the energy dependence of the CdTe and CdZnTe detector absorption efficiency. An experimental detector unit equipped with an optimized "detector-filter" set had a discrete sensitivity of 350 counts/R (±20%) in the energy range 0.06-1.2 MeV.

19. V.M. Azhazha, V.E. Kutnii, A.V. Rybka, I.N. Shlyakhov, D.V. Kutnii, A.A. Zakharchenko. Application of Detectors Based on the Wide-Gap Semiconductors CdTe, CdZnTe, and GaAs for Nuclear Power Plant Safety Monitoring // Atomic Energy, June 2002, vol. 92(6), pp.508-513.

    Abstract Full text (PDF) Units for detecting ionizing radiation which are based on ionization counters, fission chambers, and scintillation sensors are used in nuclear and radiation safety systems in nuclear power plants. In comparison, semiconductor detectors are smaller and have a small mass, a wider dynamical range, a higher quantum yield, better radiation resistance, and better energy resolution and signal/noise ratio. Investigations confirming these qualities are presented in the paper.

20. A.V. Rybka, S.A. Leonov, I.M. Prokhoretz, A.S. Abyzov, L.N. Davydov, V.E. Kutny, M.S. Rowland and C.F. Smith. Influence of detector surface processing on detector performance // Nucl. Instr. & Meth. A, 2001, vol. 458, pp.248-253.

    Abstract Full text (PDF) Characteristics of gamma-ray semiconductor detectors essentially depend on properties of crystal surface. The status of a lateral surface influences surface leakage current of the detector, and the status of a surface, on which the contacts are made, influences properties of contacts and, thus, a volume leakage current and the highest possible bias voltage. In this connection several ways of processing the lateral surface of CdZnTe and CdTe crystals grown by a high-pressure Bridgman method were investigated: chemical etching, ion cleaning, passivation. Influence of a preliminary processing of a crystal surface on the properties of ohmic contacts is investigated. An analysis of electrophysical properties of crystals subjected to surface processing is carried out.

21. V.E. Kutny, A.V. Rybka, A.S. Abyzov, L.N. Davydov, V.K. Komar, M.S. Rowland and C. F. Smith. AlSb single-crystal grown by HPBM // Nucl. Instr. & Meth. A, 2001, vol. 458, pp.448-454.

    Abstract Full text (PDF) Theoretical prognosis for AlSb places this widegap compound among the best materials for room temperature detectors and spectrometers. However, results experimentally obtained with AlSb are somewhat discouraging showing the necessity for improving the compound quality. The main difficulties connected with single-crystal growth are high reactivity of the melt with crucible material and a high volatility of Sb. In order to counteract the latter obstacle, an attempt was undertaken to synthesize and grow AlSb crystals by HPBM under the inert gas pressure of 40 atm. Different crucible materials: aluminum oxide, vitreous carbon, quartz, graphite, beryllium oxide, and zirconium oxide were tested and their comparative analysis was made. The obtained crystals were investigated and some electrophysical properties measured.

22. A.S. Abyzov, L.N. Davydov, V.E. Kutny et al. Correlation Between Spectrometric Ability and Physical Properties of Semiconductor Detectors // Functional Materials, 2000, vol. 7, no. 4(2), pp.827-835.

    Abstract Among the semiconductor crystals employed in spectrometers, the leading positions belongs to the wide-gap compounds Cd_1−xZn_xTe, CdTe, HgI₂. The question arises whether it is the final and optimal choice. In an attempt to answer it, physical parameters crucial for spectroscopic performance of a detector were selected. They include, first of all, mobility, lifetime, mean atomic number, and resistivity. Starting from the periodic table an analysis of binary compounds with tetrahedral structure was done on the basis of the selected parameters. Unfortunately, the lack of theoretical and experimental data, as well as their discrepancies do not permit to compare all the compounds. However, the existing data are summarized and analyzed.

More in Russian

1. V.E. Kutniy, D.V. Kutniy, A.V. Rybka, A.A. Verevkin, D.V. Nakonechniy, K.V. Kutniy, S.Yu. Sayenko, G.A. Kholomeev, A.V. Pilipenko. Gas-static processing of Au-CdZnTe-Au structures for X- and gamma-ray detectors // Problems of Atomic Science and Technology (PAST). Vacuum, Pure Materials, Superconductors, 2008, issue 1(17), pp.123-128.

   Abstract Full text (PDF) The influence of gas-static processing on electrophysical properties of Au-CdZnTe-Au structures for X-ray and gamma-ray detectors was investigated. The processing was conducted in laboratory-scale plant GAUS-4/2000-35 according to regime (0.32 ± 0.02 GPa, ∼ 170°C, 2 h). Influence of gas-static processing on electric resistance, J-V characteristics and spectrometric parameters of Au-CdZnTe-Au structures was determined.

2. Simulation of response function of CdZnTe detectors for gamma-radiation dosimetry // The Journal of Kharkov National University, 2008, vol. 832, Physical series "Nuclei, Particles, Fields", issue 4(40), pp.71-76.

   Abstract Full text (PDF) A procedure allowing to obtain a response function of CdZnTe planar detector used for gamma-ray dosimetry is developed based on the Monte-Carlo method. For reliable reconstruction of the detector response function the experimental spectra only from three sources: ²⁴¹Am, ¹⁵²Eu and ¹³⁷Cs will suffice. The proposed method was used for the calculation of the discrete sensitivity of CdZnTe dosimeter detector module

3. D.V. Kutniy, V.E. Kutniy, N.P. Odeychuk, V.E. Tovkanetz, A.V. Rybka, A.A. Zakharchenko. Use of the active well coincidence counter for the semiconductor neutron detector development // The Journal of Kharkov National University, 2008, vol. 823, Physical series "Nuclei, Particles, Fields", issue 3(39), pp.71-77.

   Abstract Full text (PDF) The possibility of neutron registration from isotopic source ²⁴¹AmLi by solid state semiconductor detector based on high purity germanium and Cd-converter was reviewed. The measurement of gamma background of isotopic neutron source ²⁴¹AmLi in the range 200…800 keV was conducted. The main gamma-ray lines with an intensity ≥ 2×10^-6 % were identified. It was founded that the appearance of prompt gamma-rays 558.6 and 651.3 keV was a result of neutrons and Cd-converter interaction. Efficiency of neutrons registration by coaxial germanium detector Ø50.5×42.5 mm was estimated.

4. A.A. Zakharchenko, I.M. Prokhoretz, V.E. Kutny, A.V. Rybka, M.A. Khazhmuradov. Estimation of transport properties of gamma-ray detectors with semiinsulating semiconductors // Tekhnologiya i konstruirovanie v elektronnoi apparature (Technology and design of electronic equipment), 2008, no.3, pp.41-45.

   Abstract Full text (PDF) A method of determination of charge transfer parameters in gamma-ray detectors with semiinsulating semiconductor sensor is proposed. The method applies the computation of charge collection efficiency and detector responsivity.

5. A.A. Zakharchenko, V.E. Kutny, D.V. Nakonechny, I.M. Prokhoretz, A.V. Rybka, M.A. Khazhmuradov. Methods of charge transport parameter determination for CdTe (CdZnTe) gamma-radiation detectors // The Journal of Kharkov National University, 2007, Vol. 784, Physical series "Nuclei, Particles, Fields", issue 4(36), pp.85-92.

   Abstract Full text (PDF) A comparative analysis of the methods intended to determine the charge transfer parameters (μτ)_e and (μτ)_h in active media of spectrometry and dosimetry high-resistivity semiconductor detectors is presented. A problem is studied how to determine these parameters in planar CdTe (CdZnTe) gamma-ray detectors using their experimental dosimetry characteristics and the results of computer gamma-spectra simulation. A technique is developed allowing to find out transport parameters of the tested detectors with the use of the measurement of the charge collection efficiency in low-energy spectral range (e.g., with 59.54 keV ²⁴¹Am peak), measurement of the detector response in high-energy range (e.g., with line 661.67 keV ¹³⁷Cs peak) and comparing these data with the results of simulation. The proposed method can be applied to the development of new spectrometric and dosimetry radiation safety devices and to the operative testing of such devices working in high-intensity radiation fields.

6. V.V. Levenets, A.P. Omelnik, A.A. Shchur, V.N. Borisenko, V.E. Kutny, A.V. Rybka, I.N. Shlyakhov, A.A. Zakharchenko. Gamma- and alpha-radiation spectrometry with CdTe (CdZnTe)semiconductor detectors // Yaderna fС–zika ta energetyka (Nuclear physics and energy), 2007, no.4(22), pp.109-113.

   Abstract Full text (PDF) The results of research of spectrometric performances of CdTe (CdZnTe) detectors at registration of 15 - 500 keV gamma-rays and 4 - 8 MeV alpha particles are presented. It is shown that such detectors can be used for analysis purposes in identification of elements from La to Pu with registration of K-series characteristic radiation and for particles spectrometry in nuclear reaction method and at isotope identification.

7. A.A. Zakharchenko, D.V. Nakonechny, I.N. Shlyakhov, A.V. Rybka, V.E. Kutny, M.A. Khazhmuradov. Simulation of energy dependence of responsivity in gamma-ray CdTe (CdZnTe) detectors // Tekhnologiya i konstruirovanie v elektronnoi apparature (Technology and design of electronic equipment), 2007, no.1, pp.28-31.

   Abstract Full text (PDF) In the developed model the methods of correction of responsivity energy dependence in gamma-ray CdTe (CdZnTe) detectors in the range from 50 to 2000 keV are investigated.

8. V.M. Azhazha, V.E. Kutny, A.V. Rybka, L.N. Davydov, I.N. Shlyakhov, A.A. Zakharchenko, D.V. Kutny, D.V. Nakonechny. Devices with CdTe and CdZnTe for technological control and monitoring of radiation environment at NPP //Nauka ta innovatsii (Science and innovations), 2006, vol.2, no.6, pp.31-38.

   Abstract Devices using wide-gap semiconductor compounds CdTe, CdZnTe: X- and gamma-ray wide-range dosimeter and emergency dose rate dosimeter are described. X- and gamma-ray detectors with CdTe, CdZnTe sensors have a number of advantages, which allow successfully apply them for dosimetry and spectrometry of different radiation sources. The advantages of CdZnTe detectors lie in an ability to measure wide energy and fluence ranges of photons, high registration efficiency and satisfactory energy resolution without necessity of detector deep cooling. The developed devices are designed for of radiation control systems and technological monitoring at NPP and in nuclear industry. They also can be used in analysis of radioactive waste. The dosimetry performances of these devices are presented.

9. D.V. Kutny, I.M. Prokhorets, A.V. Rybka, D.V. Nakonechny, S.I, Prokhorets, A.A. Zaharchenko, K.V. Kutny. Technique of measurement of electromagnetic radiation by semiconductor detectors // Problems of Atomic Science and Technology (PAST). Vacuum, Pure Materials, Superconductors, 2006, issue 1(15), pp.163-169.

   Abstract Full text (PDF) Sources of radiations emit alpha-particles, positrons, electron, electromagnetic radiation (gamma-quanta, X-ray radiation), neutrons, fragments of nuclear fission etc. Each form of radiation is characterized by many parameters, and first of all, by spectrum of emitted energy. The detection of all forms of radiation based on the processes occurring at passage of radiation through matter. The paper considers the particularities of using semiconductor detectors for gamma-ray spectrometry. By methods of mathematical simulation the energy resolution of CdZnTe detectors with thickness of 1 and 10 mm is estimated. A choice of parameters of a spectrometer channel in experiments with CdZnTe (CdTe) detectors is validated.

10. L.N. Davydov, A.A. Zakharchenko, D.V. Kutny, V.E. Kutny, I.M. Neklyudov, A.V. Rybka, I.N. Shlyakhov. Radiation hardness of semiconductor detectors for corpuscular and gamma-radiation // The Journal of Kharkov National University, 2005, Vol. 657, Physical series "Nuclei, Particles, Fields", issue 1(26), pp.3-22.

    Abstract Full text (PDF) During its operation an X-ray or γ-ray semiconductor detector is intrinsically subjected to radiation damage, which deteriorates the device characteristics and can cause its failure. The radiation damage in γ-ray dosimeter semiconductor detectors degrades their count characteristics. In spectroscopy semiconductor detectors the energy resolution aggravates, the leakage current increases, and the position of the photopeak shifts to smaller energy values. In this review the current level of understanding of the semiconductor detectors radiation degradation is described and some available methods of detector service-life prolongation are pointed out. The information about radiation hardness of silicon detectors as the most investigated, and of wide-zone semiconductor detectors, recently widely applied, such as CVD diamond, CdTe and CdZnTe, is given. The researches of radiation service-life of dosimetry and spectrometry detectors from CdTe and CdZnTe, carried out in NSC KIPT, are described. The obtained count characteristics and ¹³⁷Cs pulse spectra are indicated as functions of an absorbed doze of gamma-radiation. It is shown, that the detectors from CdTe and CdZnTe have increased radiation hardness compared to conventional silicon detectors. The spectrometry detectors conserve the ability to discriminate the gamma-radiation energy up to the absorbed dose about 20 kGy, and the dosimetry detectors continue to register the dose up to several hundreds of kGy.

11. A.S.Abyzov, V.M. Azhazha, L.N. Davydov, G.P.Kovtun, V.E. Kutny, A.V. Rybka. Selection of semiconductor material for gamma-ray detectors // Tekhnologiya i konstruirovanie v elektronnoi apparature (Technology and design of electronic equipment), 2004, no.3, pp.3-6.

    Abstract Full text (PDF) Binary semiconductor compounds with tetrahedral structure are analyzed on the basis of physical parameters, critical for the device detecting ability.

12. S.Leonov, D.Kutnij, D.Nakonechny, L.Davydov, A.Zakharchenko, V.Kutnij, A.Rybka. Ion-plasma passivation of CdZnTe crystal surface // Problems of Atomic Science and Technology (PAST). Vacuum, Pure Materials, Superconductors, 2004, issue 6(14), pp.147-151.

    Abstract Full text (PDF) A method of ion plasma passivation, proposed earlier by the authors for lateral surface coating of semiinsulating semiconductor crystal, like CdZnTe, is presented in some detail. It is now shown that the passivation can be successfully realized not only with TiO₂ coating but also with coatings made from Al₂O₃ and ZrO₂. The voltage-current characteristics of CdZnTe detector sensors with passivated lateral surface are investigated. The temperature dependence of these characteristics is analyzed. It is shown, that even at T≈0°C the passivated surface does not influence the CdZnTe detector performance.

13. V.E. Kutnij, A.V. Rybka, D.V. Kutnij, I.N. Shlyahov, D.V. Nakonechny. Development of dosimetric and spectrometric devices to detect gamma-irradiation based on semiconductor alloys CdTe(CdZnTe) for NPP of Ukraine // Problems of Atomic Science and Technology (PAST). Physics of Radiation Effect and Radiation Materials Science, 2004, issue 3(85), pp.96-100.

    Abstract Full text (PDF) In existing systems of nuclear and radiation safety of Ukrainian NPP the used radiation detector modules are based on ionization counters, fission chambers, and scintillation sensors. In comparison with them the semiconductor detectors have smaller dimensions and weight, wider dynamic range, higher quantum output, radiating stability, best energy resolution and signal-to-noise relation. The investigations that confirm the specified properties are given in this work.

14. L.N. Davydov, A.N. Dovbnya, A.A. Zakharchenko, V.E. Kutny, D.V. Kutny, I.M. Prokhoretz, A.V. Rybka, I.N. Shlyakhov. Application of semiconductor detectors for the account and monitoring of radioactive waste // Problems of Atomic Science and Technology (PAST). Physics of Radiation Effect and Radiation Materials Science, 2002, issue 3(81), pp.142-146.

    Abstract Full text (PDF) The possibilities and development status of the contemporary semiconductor detectors and detecting devices intended for radiation monitoring at nuclear industry enterprises, including Chernobyl Shelter and depositories of nuclear wastes are shown. Such devices, created in the last years, can be successfully used for measurements of the gamma-radiation dose rate as well as for the isotope composition evaluation of nuclear materials and wastes, both during the work cycles and in emergency situations.

15. V.E. Kutny, A.V. Rybka, I.M. Prokhoretz, L.N. Davydov, A.S. Abyzov, A.N. Dovbnya, S.P. Karasev, V.L. Uvarov, I.N. Shlyakhov. Radiation hardness investigation of CdTe and CdZnTe ionizing radiation detectors // Problems of Atomic Science and Technology (PAST). Physics of Radiation Effect and Radiation Materials Science, 2000, issue 4(78), pp.212-214.

    Abstract Full text (PDF) During the operation of semiconductor radiation detectors the radiation damage is created, which worsens device properties and put them even out of operation. In spectrometers the energy resolution deteriorates, the leakage current increases, the position of photopeak is shifted to low energy. In dosimeters their count performances worsen. The main purpose of the present study was the establishment of radiation lifetime of CdTe and CdZnTe dosimetry detectors. CdTe and CdZnTe detectors, not possessing spectrometric quality, were chosen for tests in dosimetry mode. The dependence of the detectors counting performances on the absorbed doze was determined. In particular, it was found that CdZnTe retains the sensitivity to registration of gamma-radiation in the count mode up to absorbed doze of 75 MR, while the radiation degradation of CdTe detectors is observed to begin at smaller dozes (20 MR).

16. A.V. Rybka, I.M. Prokhorets, I.N. Shlyahov, A.A. Zakharchenko, A.A. Blinkin, L.N. Davydov, M.A. Kuzmichev, D.V. Kutnij, A.N. Orobinsky, N.I. Kravchenko. Dosimetric performance of CdTe (CdZnTe) X- and gamma-ray detectors // Problems of Atomic Science and Technology (PAST). Physics of Radiation Effect and Radiation Materials Science, 2000, issue 4(78), pp.208-211.

    Abstract Full text (PDF) The effect of X- and gamma-radiation on working performances of CdTe and CdZnTe detectors is investigated. The CdTe crystals were obtained by a traditional Bridgman method, and CdZnTe by Bridgman method at high pressure of inert gas. The count performances of detectors, their discrete responsivity and dose rate dependence for ²⁴¹Am, ¹³⁷Cs and ⁶⁰Co sources are indicated. For ¹³⁷Cs the discrete responsivity is about 60 pulse/μR at dose rate up to 1 R/h. The researches have shown that the broadening of dose rate range is possible with the modification of detector working volume of the signal discrimination threshold.

17. Yu.A. Gribanov, B.S. Ringis, B.G. Skoromny, V.E. Kutny, A.V. Rybka, I.N. Shlyakhov. Perspectives of using CdTe (CdZnTe) semiconductor materials at Ukrainiam NPP reconstruction // Problems of Atomic Science and Technology (PAST). Physics of Radiation Effect and Radiation Materials Science, 2000, issue 4(78), pp.203-207.

    Abstract Full text (PDF) The reconstruction of systems of radiation monitoring at Ukrainian NPP is an actual problem, because the regular NPP equipment AKRB-03 was developed in the late 1970s and has already exhausted its safe life potential. Besides, the radiation safety regulations at nuclear industry have undergone significant modifications: new standards NRBU-98, OPB-88, SPAS-88, etc. are implemented, which causes a discordance between the existing means of radiation monitoring and the requirements of these documents. In this connection the automated monitoring system of radiation safety (AMSRS), intended for complex monitoring of radiation safety at NPP, was developed. The AMSRS design solution includes technical, mathematical, information, linguistic, software, metrological and organizational maintenance. Moreover the solutions ensuring the requirements of electromagnetic compatibility and serviceability of the AMSRS equipment in complex radiation environment are found. All the equipment of the developed system meet "Special Requirements on Equipment Delivery for NPP", possess guarantee quality assurance, have high reliability, seismic resistance and fire safety. The paper describes general principles of AMSRS design.