Browsing by Author "Drozdowicz, Krzysztof"
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Item Angular-energy distributions of neutrons emitted from the Wendelstein stellarator – Monte Carlo simulations(Institute of Nuclear Physics Polish Academy of Sciences, 2009) Tracz, Grzegorz; Drozdowicz, KrzysztofAngular-energy distributions of neutron currents expected from the Wendelstein 7-X stellarator have been calculated by means of Monte Carlo methods using a simplified model of the stellarator. The MCNP5 code has been employed. The obtained spectra are to be used to design five sets of neutron and gamma detectors placed above this D-D fusion reactor. The counters are to provide information concerning both thermonuclear plasma diagnostics and dosimetry.Item Assumptions for the design of a neutron pinhole camera dedicated to the PF-24 device(Institute of Nuclear Physics Polish Academy of Sciences, 2014) Scholz, Marek; Bielecki, Jakub; Wójcik-Gargula, Anna; Wiącek, Urszula; Drozdowicz, Krzysztof; Igielski, Andrzej; Kulińska, Agnieszka; Tracz, Grzegorz; Woźnicka, UrszulaThe report presents main assumptions on the design of the neutron pinhole camera dedicated to the PF-24 (Plasma Focus) device. The pinhole camera will be used for the investigation of the spatial and temporal distributions of DD neutrons from the PF-24 source. It makes use of principles of the optical geometry adopted for neutron imaging. In the report the evaluation of pinhole geometrical layout has been made on the basis of principles of the geometrical optics. A further optimization of the pinhole geometry has been carried out by means of neutron transport calculations (the MCNP code). The main aim of this report is to provide information on technical solutions for the neutron pinhole.Item Budowa modeli geochemiczno-mineralogicznych na podstawie danych uzyskiwanych z zaawansowanych metod geofizyki jądrowej. Część 1(Institute of Nuclear Physics Polish Academy of Sciences, 2007) Woźnicka, Urszula; Cywicka-Jakiel, Teresa; Drabina, Andrzej; Dworak, Dominik; Tracz, Grzegorz; Drozdowicz, Krzysztof; Zorski, Tomasz; Ossowski, Andrzej; Środoń, Jan; Kawiak, Tadeusz; Bakowska, Dorota; Zielińska, Małgorzata; Zalewska, JadwigaAn extensive set of conventional and special core analysis measurements, complemented by additional chemical and mineralogical analyses was performed, forming the basis for the evaluation of the complex thin bedded gas-bearing shaly-sand formations of Miocene age in the Carpathian Foredeep region of Southern Poland. Mineralogy was established by using full elemental composition, XRD method, total surface area and cation exchange capacity (CEC). The analysis showed that the most important clay component is illite – smectite mixed layer. Statistical multivariate analysis of all data helped to set up a comprehensive general petrophysical model. For the notoriously difficult CEC information for the rock matrix we could establish a reliable correlation (corr. coefficient r2 around 0.95) between thermal neutron absorption cross section SIGMA and total natural radioactivity GR with CEC, with boron and rare earth elements the two most important SIGMA contributors in the rock matrix. This good correlation permits a continuous on-line CEC determination and therefore a reliable application of the Waxman-Smits water saturation model to properly take into account the clay mineral effects in evaluating water saturation.Item Calculations of the neutron-induced activity in air inside the Cuboid 2 of the High-Resolution Neutron Spectrometer for ITER(Institute of Nuclear Physics Polish Academy of Sciences, 2017-01) Wójcik-Gargula, Anna; Tracz, Grzegorz; Scholz, Marek; Drozdowicz, KrzysztofThis report presents results of the calculations performed in order to predict the neutron - induced activity in air inside the second Cuboid in the ITER equatorial port cell #1 where the Time of Flight detectors of the High Resolution Neutron Spectrometer are planned to be installed. Based on the neutron spectra generated by 2.45 MeV and 14 MeV neutron sources, calculated with the MCNP code, it was possible to determine the activity of the dominant radionuclides using the FISPACT-II Transmutation - Activation Inventory Code and the EAF - 2010 nuclear data library. The results show that although long - lived isotopes such as e.g. H-3 or C-14 are produced following neutron irradiation, their activity will not be significant since they will not exceed the maximum permissible levels.Item Detection of delayed neutrons from neutron activation of fissionable substance samples. Monte Carlo modelling of response of the DET-12 device(Institute of Nuclear Physics Polish Academy of Sciences, 2013) Tracz, Grzegorz; Bieńkowska, Barbara; Drozdowicz, KrzysztofActivation of fissionable elements by neutrons has been considered as a possible diagnostics of D-D and D-T fusion plasma. Fission caused by fusion neutrons leads up to emission of secondary neutrons: prompt and delayed. Proper interpretation of the time decay of delayed neutrons enables an assessment of the parameters of the primary neutron flux inducing fission. Monte Carlo calculations have been carried out by means of the MCNP code in order to elaborate the method considered. Three nuclides: pure 235U, 238U and 232Th, and additionally sintered UO2 have been selected as possible materials for the sample to be irradiated. Four energies of neutrons irradiating samples have been chosen: thermal, fast and two high ones. Computations have been accomplished for two variants: pure physical effect and real experimental conditions of neutron registration in the DET-12 device designed and built in IFJ PAN. Decay curves have been obtained for each case. Detection efficiency of DET-12 has been also estimated.Item Feasibility study of experimental detection of the hydrogen content in rock material by a pulsed neutron method(Institute of Nuclear Physics Polish Academy of Sciences, 2003) Drozdowicz, Krzysztof; Drabina, Andrzej; Dąbrowska, Joanna; Gabańska, Barbara; Igielski, Andrzej; Janik, Władysław; Krynicka, Ewa; Kurowski, Arkadiusz; Wiącek, Urszula; Woźnicka, UrszulaTheoretical principles of a pulsed neutron method to measure the water or hydrogen content in a rock material have been tested on the experimental set-up at the fast neutron generator in the INP. The time decay constant of the thermal neutron flux in the samples has been measured as a function of the hydrogen content. Dry crumbled granite has been used as a rock sample. The hydrogen content has varied due to addition of a defined amount of polyethylene (0 to 20 %). A few arrangements (neutron source + sample) have been tried. A dedicated pulsed thermal neutron source has been designed and built. The measuring set-up has been chosen for a final elaboration of the method.Item Influence of the water content in rock on the thermal neutron diffusion and diffusion cooling coefficients (by Monte Carlo simulations). II: – Quartz(Institute of Nuclear Physics Polish Academy of Sciences, 2003) Drozdowicz, Krzysztof; Krynicka, Ewa; Dąbrowska, JoannaThe dependence of the thermal neutron diffusion parameters on the water content w in quartz, SiO2, has been studied by means of Monte Carlo simulations of the pulsed neutron experiments for a number of series of samples. The density-removed diffusion cooling coefficient CM varies hyperbolically between 39 400 000 and 4940 cm4s–1(g/cm3)3 at the water content in the full range 0 ≤ w ≤.1. The obtained function CM(w) is compared with the analogous dependence for moisturized dolomite.Item Measurements of the effective thermal neutron absorption cross-section in multi-grain model(Institute of Nuclear Physics Polish Academy of Sciences, 2005) Drozdowicz, Krzysztof; Gabańska, Barbara; Igielski, Andrzej; Krynicka, Ewa; Schneider, Krystyna; Woźnicka, UrszulaThe effective macroscopic absorption cross-section Σaeff of thermal neutrons in a grained medium differs from the corresponding cross-section Σahom in the homogeneous medium consisting of the same components, contributing in the same amounts. The ratio of these cross-sections defines the grain parameter, G, which is a measure of heterogeneity of the system for neutron absorption. Heterogeneous models have been built as two- or three-component systems (Ag, Cu and Co3O4 grains distributed in a regular grid in Plexiglas, in various proportions between them). The effective absorption cross-section has been measured and the experimental grain parameter has been found for each model. The obtained values are in the interval 0.34 < G < 0.58, while G = 1 means the homogeneous material.Item Method of interpretation of measurements of delayed neutrons in the DET-12 device(Institute of Nuclear Physics Polish Academy of Sciences, 2014) Bieńkowska, Barbara; Prokopowicz, Rafał; Drozdowicz, Krzysztof; Woźnicka, UrszulaDET-12 is a device to measure delayed neutrons from fissions in fissionable material samples which were activated in the primary neutron flux from D-T or D-D reactions in hot plasma of big fusion devices (tokamaks, stellarators). In the paper, a method is outlined how to interpret the registered time decay of delayed neutrons in order to obtain information on intensity of the primary neutron flux. The method combines a restoration of the decay function (multi-exponential) from the data stored in a multiscaler regime and a Monte Carlo calculation of a basic approximation of the neutron energy spectrum.Item Physical assumptions for a design of the DET-12 chamber for detection of delayed neutrons(Institute of Nuclear Physics Polish Academy of Sciences, 2014) Bieńkowska, Barbara; Drozdowicz, Krzysztof; Gabańska, Barbara; Igielski, Andrzej; Prokopowicz, Rafał; Wiącek, Urszula; Woźnicka, UrszulaPhysical assumptions have been outlined to design a new device (DET-12) for measurements of delayed neutron emitted from samples of fissionable materials activated with neutrons at big fusion-plasma devices. The aim is to support in this way a classic neutron activation method used as one of the hot plasma diagnostics at tokamaks or stellarators. Physical fundamentals of generation of the delayed neutrons are mentioned and a resulting concept of the measuring chamber is presented. A general size and dimensions of particular constituent material layers, and a number and placement of neutron detectors are optimized by means of Monte Carlo modelling of the neutron transport. Recommendations for a technical design of the measuring chamber are formulated.Item Preliminary study of a target-moderator assembly for a linac-based neutron source(Institute of Nuclear Physics Polish Academy of Sciences, 2005) Bartalucci, Sergio; Drozdowicz, Krzysztof; Dworak, Dominik; Tracz, Grzegorz; Angelov, VladimirThe report concerns a design of a future pulsed neutron source at an electron linac. A massive target is irradiated with an electron beam and the neutrons are generated mainly by collisions of the bremsstrahlung photons. A first step of the work, related to the optimization of the target materials and geometry using numerical simulations, is presented. The Monte Carlo FLUKA and MCNP codes are used. The water-cooled tantalum target is investigated: 0.41 cm Ta slices separated with 0.15 cm H2O layers. Two different sizes of the cylindrical target are assumed: 5 or 2.5 cm in diameter. The 1 GeV and 1.5 GeV electron beams are tested. The outgoing neutron angular-energy spectra are presented. The angular space 0°÷180° is divided in 10-degree intervals. The neutron emission in the direction perpendicular to the originated electron beam has been observed in the particularly narrow (2°) interval. The FLUKA results of a comparison of the neutron currents in main directions (0° – forward, 90° – perpendicular, 180° – backward) are as follows. For the 5 cm target the distribution is quite uniform: at 1 GeV input electrons – n(180°)/n(0°) = 1.00, n(90°)/n(0°) = 1.04, and at 1.5 GeV electrons – n(180°)/n(0°) = 0.91, n(90°)/n(0°) = 1.00. For the 2.5 cm target the relative neutron current in the perpendicular direction is significantly higher: at 1 GeV electrons – n(180°)/n(0°) = 1.02, n(90°)/n(0°) = 1.53, and at 1.5 GeV electrons – n(180°)/n(0°) = 0.93, n(90°)/n(0°) = 1.45. In the cases when the FLUKA and MCNP simulation results can be compared, a high similarity of the neutron energy distributions is stated although a possible discrepancy of the values reaches 20 %. Spectra of the accompanying radiation (photons, electrons, positrons, protons, charged pions) have been also obtained. The angular distributions of photons, electrons, and positrons are strongly peaked up towards the beam direction. Their emission at 90° is significantly lower, which means a decrease of the background in this direction. The energy deposition in the target is estimated on a simplified model with no cooling system. About 63 % of energy is then stored in the space at ca. 20÷40 % target length along the initial electron beam axis.Item Principles of a method to use CVD diamond detectors for spectrometric measurements of particles in mixed radiation field emitted by D-D and D-T fusion plasmas(Institute of Nuclear Physics Polish Academy of Sciences, 2014) Drozdowicz, Krzysztof; Dankowski, Jan; Igielski, Andrzej; Jaskóła, Marcin; Korman, Andrzej; Kurowski, Arkadiusz; Marczewska, Barbara; Nowak, Tomasz; Wiącek, Urszula; Woźnicka, Urszula; Gabańska, BarbaraFuture thermonuclear reactors for needs of power plants will operate with the deuterium-tritium fuel. Neutron, alpha particle, and energy are created in the fusion reaction between these isotopes. Measurement of energy of the reaction products is important to control energetic balance in the thermonuclear plasma. Fast neutrons (14 MeV) should deliver energy outside the tokamak. Alpha particles are the ash of the reaction but they should also leave their energy (3.6 MeV) in the plasma to maintain the fusion reaction. Therefore, knowledge of the energy of alpha particles escaping from plasma (the lost alpha particles) is essential. Because of a short range of alpha particles the measurement has to be performed inside the tokamak, in harsh surrounding (high temperature and high particle fluxes). Diamond seems to be a proper material for use it as a semiconductor detector under those conditions. A diamond detector (synthetic high purity CVD monocrystal) was tested in aspect of its potential application for spectrometric diagnostic of the ions in tokamaks. The energy calibration of the diamond detectors of the different thickness was performed using isotopic sources: energies around 5 MeV from the 239Pu + 241Am + 244Cm source, and 6.8 and 8.7 MeV from the 212Bi + 212Po source. Additionally, monoenergetic ions beams (alpha particles and protons) were obtained from a van de Graaff accelerator in the 0.4 – 2 MeV energy range. A very good linearity of the amplitude signal vs. energy was obtained. At any working tokamak, a mixed radiation field is present consisting of various particles, like n, α, γ, p, d, t. Their contributions fluctuate depending on a regime of tokamak work and on plasma instabilities. Thus, the CVD diamond detector response in a mixed radiation field can be properly studied only in well-defined conditions of a laboratory experiment. Detection of ions and neutrons was performed at our 14 MeV neutron generator, IGN-14, where (i) the same nuclear reaction as in the D-T plasma occurs and (ii) also other types of radiation similar as at tokamaks are observed (owing to a number of different reactions on the generator target). A new measuring chamber at IGN-14 was designed and built to make possible observation of responses of detectors placed symmetrically or at different angles in respect to the primary ion beam. Two identical or different type detectors can be compared at the same time. A complex spectrograms were obtained and analysed to distinguish signals from various particles.Item Sensitivity of the Thermal Neutron Time Decay to the Hydrogen Content in a Rock Sample(Institute of Nuclear Physics Polish Academy of Sciences, 2004) Drozdowicz, Krzysztof; Dąbrowska, Joanna; Gabańska, Barbara; Igielski, Andrzej; Janik, Władysław; Krynicka, Ewa; Kurowski, Arkadiusz; Niedźwiedź, K.; Wiącek, Urszula; Woźnicka, UrszulaA pulsed neutron method to measure the water or hydrogen content in a rock material has been tested on the experimental set-up at the fast neutron generator in the IFJ PAN. A dedicated pulsed thermal neutron source has been designed, built and added to this set-up. The test experiments have been done using dry crumbled granite as the rock matrix. The hydrogen content in samples has varied due to an addition of a defined amount of polyethylene. The time decay constant of the pulsed thermal neutron flux has been measured as a function of polyethylene content in granite+polyethylene samples. The experimental results have been supplemented with Monte Carlo simulations of the experiments. Analytical estimations of the time decay constant in the examined geometry have also been done. Difficulties of the proposed experimental method at low values of the hydrogen content are discussed. The proposed method using the pulsed neutron source to determine the hydrogen content which is less than 10 %, can be applied for rock samples of volume about 30 dm3. For higher hydrogen content the volume of the sample can be lower – about 7 dm3.Item Spectrometric properties of the CVD diamond detector for measurement of the ‘lost alpha particles’(Institute of Nuclear Physics Polish Academy of Sciences, 2010) Wodniak, Iwona; Dankowski, Jan; Drozdowicz, Krzysztof; Gabańska, Barbara; Igielski, Andrzej; Kurowski, Arkadiusz; Maczewska, Barbara; Nowak, TomaszMeasurement of energy of the ‘escaping alpha particles’ from the thermonuclear reaction in the tokamak is important to get information on the energetic balance in future thermonuclear reactors producing electrical energy. Detectors will work in a harsh environment (high fluxes of particles, high temperature). Synthetic (CVD) diamond can be used in this case as a semiconductor detector. Tests with such a detector are described. Energy calibration has been carried out with a triple alpha particle isotopic source, 239Pu, 241Am, 244Cm (PAC), with the α energy peaks at ca. 5.2, 5.5 and 5.8 MeV. A very good energy resolution has been obtained, comparable with the resolution of the classic silicon detector. Energy response has been also investigated with the use of monoenergetic alpha particle beams (0.4 to 2 MeV) from the Van de Graaf accelerator. The amplitude linearity of the signal is very good, including besides results of measurements with the PAC source.Item Technical design and operation tests of the DET-12 device for detection of delayed neutrons(Institute of Nuclear Physics Polish Academy of Sciences, 2014) Bieńkowska, Barbara; Drozdowicz, Krzysztof; Gabańska, Barbara; Igielski, Andrzej; Janik, Władysław; Kurowski, Arkadiusz; Tracz, Grzegorz; Wiącek, Urszula; Dankowski, JanA technical design of the device for detection of delayed neutrons emitted from neutron-activated fissionable material samples has been performed according to physical assumptions which were earlier elaborated. The DET-12 device was constructed. The detection system was composed, consisting of twelve 3He neutron detectors, related electronics lines, and the data acquisition and recording system. The detectors were adjusted to work in groups by three connected to one preamplifier, considering a weak intensity of emission of the delayed neutrons. Laboratory measurement tests of the device operation were made with use of an isotopic neutron source. A total efficiency of neutron detection in DET-12 was experimentally determined and a relative benchmark calculation was made by means of a Monte Carlo modelling of the neutron transport in the device from the source to detectors.Item Test of the European Transport Solver in the frame of Integrated Tokamak Modelling(Institute of Nuclear Physics Polish Academy of Sciences, 2011) Twaróg, Dariusz; Stankiewicz, Roman; Drozdowicz, KrzysztofThe European Transport Solver (ETS) is developed in the frame of Project 3 of EFDA Integrated Tokamak Modeling Task Force. Several numerical methods are implemented in the ETS. This paper presents a method of verification of implemented numerical schemes for the case of solutions which take into account existence of the transport barrier in the tokamak plasma. A manufactured solution method for generation of exact solutions is developed for this case. The exact solutions are compared with the numerical ones for a simple transport model. Numerical tests demonstrate that numerical procedures: solvers 3 and 7 can reproduce analytic solutions with a discontinouity quite well.Item The SOF detectors in pulsed neutron measurements(Institute of Nuclear Physics Polish Academy of Sciences, 2009) Igielski, Andrzej; Gabańska, Barbara; Drozdowicz, Krzysztof; Janik, Władysław; Kurowski, ArkadiuszThe time decay of the pulsed thermal neutron flux has been measured with quasi-point SOF detectors (scintillator with the optical fiber). The detectors have been placed at three positions in a 12 cm cube of polyethylene. The time decay constants of the fundamental exponential mode of the thermal neutron flux have been determined and compared with results of a reference measurement using 3He neutron detectors at the cube surface and with a theoretical result from the thermal neutron diffusion theory.