Repository of the Institute of Nuclear Physics PAN
Not a member yet
364 research outputs found
Sort by
Przemiany strukturalne i magnetyczne wywołane absorpcją wodoru w związkach ziem rzadkich z manganem o strukturze typu faz Lavesa C14 i C15
No full textMetody analityczne dla określania odporności systemów hydrogeologicznych na wpływ zanieczyszczeń antropogenicznych
No full textW pracy przedstawiona jest metoda oceny odporności systemów hydrologicznych na wpływy zanieczyszczeń antropogenicznych przy użyciu znaczników środowiskowych. Odporność systemów wód podziemnych na zanieczyszczenia antropogeniczne jest skorelowana z wiekiem wody, który można wyznaczyć metodami znaczników środowiskowych. W pracy opisano trzy układy pomiarowe do oznaczania stężeń gazów cieplarnianych: sześciofluorku siarki (SF6) i freonów F-11, F12 oraz gazów szlachetnych neonu (Ne), argonu (Ar) oraz helu (He). Pierwszy układ do pomiaru stężenia SF6 i freonów F-11 i F-12 składa się z chromatografu gazowego typu N504 zasilany jest gazem nośnym azotem o czystości 6,0. Wyposażony jest w dwie kolumny pakowane K1 i K2 pracujące w temperaturze 60oC z zastosowaniem systemu „back-flush” przełączania kolumn i w detektor wychwytu elektronów (ECD) produkcji IFJ PAN pracujący w temperaturze 300oC. Drugi układ do pomiaru stężenia gazów szlachetnych argonu i neonu, składa się z dwutorowego chromatografu gazowego typu Shimadzu. Wyposażony jest w dwie kolumny K4 i K5 pracujące w temperaturze 30oC i w detektory cieplnoprzewodnościowy (TCD) do analiz argonu i detektor helowy z wyładowaniem impulsowym (PDHID) do analiz neonu. Chromatograf ten zasilany jest gazem nośnym helem 6.0 w torze detektora PDHiD oraz w torze detektora TCD. Trzeci układ do pomiaru stężenia helu, składa się z chromatografu gazowego wyposażonego w detektor cieplnoprzewodnościowy TCD oraz trzy kolumny pakowane wypełnione sitem cząsteczkowym typu 5A i węglem aktywnym. Gazem nośnym w tym układzie jest argon 6.0. Poziomy wykrywalności LOD dla poszczególnych układów pomiarowych dla badanych związków wynoszą: 0,06 fmol/L dla SF6, 15 fmol/L dla F-11, 10 fmol/L dla F-12, 1,9·10-8 cm3STP/cm3 dla Ne, 3,1·10-6 cm3STP/cm3 dla Ar oraz 1,2·10-8cm3STP/gH2O dla He
Linia eksperymentalna do napromieniania pojedynczych żywych komórek przy stanowisku mikrowiązki rentgenowskiej w IFJ PAN. Opis techniczny
No full textX-ray experimental microbeam line for single live cells irradiation has been constructed at the Institute of Nuclear Physics PAN. The facility is based on an open type X-ray tube with microfocusing (the X-ray emission spot size is about 2 micrometers in diameter) and anode exchange ability. In the microdosimetry experiment a Titanium anode with the 4.5 keV energy of Ka characteristic radiation line is used. The X-ray radiation, emitted from the spot into a cone of 120 degrees angle, is focused on the sample using the X-ray focusing multilayer mirrors in the Montel geometry. The focusing distance is 32 mm, and the focal spot is about 20 micrometers in diameter. The beam image can be observed using the X-ray sensitive CCD camera, as well as with the use of an optical microscope and the P43 scintillator screen. Cells are seeded on a thin mylar foil, which is mounted on a drilled opening in the bottom of the Petri dish. After visual selection of cells dedicated to irradiate, and setting of experimental parameters, the irradiation process is carried out automatically, and cells are irradiated with a controlled X-ray dose.Praca finansowana ze środków MNiSW, grant nr NN 518 295 54
Effect of atomic-scale microstructure on hardness, fracture and oxidation of metal-nitride coatings
No full textThe main goal of this habilitation thesis is to identify and classify the types of interfaces and their role in hardening mechanisms in differently structured transition metal nitride coatings, by direct transmission electron microscopy (TEM) observations. The investigated coatings have been divided according to their structure into three groups: columnar coatings, multilayers and nanocomposites. The microstructural aspects of all three groups have been extensively studied by TEM in as-deposited and heat-treated state or after indentation in order to better visualize the mechanisms governing the coating behavior during plastic deformation. Also the combination of different chemical compositions and their influence on the coating’s microstructure has been analyzed. TEM studies down to the atomic scale, of a compositionally graded TiAlSiN coating allowed putting some light onto the mechanism of formation of the nanocomposite structure. The images taken in the Ti-rich part of the coating showed crystalline columns with neat interfaces, followed by a progressive appearance first of a crystalline and then of an amorphous boundary phase as the Al+Si concentration was increasing. At the top part of the coating the well-known nanocomposite structure consisting of crystalline grains surrounded by an amorphous matrix was observed. In addition it could be shown that the nanocomposite structure, exhibiting high hardness, can only be formed with two phases having sharp interfaces such as TiN/SiN. It was not possible to make a hardness enhanced nanocomposite out of AlN and SiN. This was due to local epitaxy at AlN/SiN interfaces, investigated on a models system of AlN/SiN multilayers. Indeed, it was found that 0.7 nm of SiN, corresponding to about two monolayers, grew
crystalline on AlN favoring epitaxy. The nanocomposite structure is not the only way to achieve a hardness enhancement in these coatings: also columnar coatings can be hard,provided a sufficient density of dislocation barriers, not in form of column boundaries, is present. Two solutions to increase the density of dislocation barriers are presented: one consists in the introduction of compositionally graded multilayers, which distort the lattice but do not obstruct the columnar growth. The second solution is a phase modulated structure i.e. inside the columns zones of different phases are formed as it is the case for cubic and hexagonal NbN, which nevertheless has a columnar structure. In multilayered coatings three types of interfaces, influencing their properties were observed: completely epitaxial, such as in AlN 10 nm/SiN<0.7 nm layers or NbN/CrN at the NbN/CrN interfaces in the growth direction, semicoherent, with local epitaxy and noncoherent such as in TiN/SiN coatings. All of them were barriers for dislocation movement making thus these coatings harder that their reference columnar layouts. To better visualize and identify the hardening mechanisms based on dislocation blocking in metal nitride coatings, plastic deformation was deliberately induced by nanoindentation. Columnar and multilayered coatings have been extensively investigated by post-mortemTEM observations of indents cross-sections. In general, all coatings containing TiN, independently on their structure or layer thickness, deformed by shear sliding at grain boundaries. This mechanism was observed on two different scales: either entire pieces of multilayers or individual grains were vertically displaced over distances of several nanometers. It was particularly well visible for the NbN/TiN and the TiN/amorphous-SiN combinations. By microstructural observations it could be shown that the substrate governs the deformation in columnar TiN coatings. In the case of columnar TiN deposited on a soft Si substrate during indentation the columns underwent shear sliding at grain boundaries and were pushed into the substrate forming steps at the interface. If columnar TiN is grown on polycrystalline, hard WC-Co substrate, cracks at co lumnar boundaries are generated. Moreover, these columns, which grow on the soft Co matrix, are also pushed into it, similarly to the TiN/Si combination. Conversely, those columns, which grow on the hard WC grains are bent and internally fractured. The type of coating structure and thus the interfaces play an important role in oxidation resistance. It could be proved, by microstructural TEM investigations, that coatings with columnar grains, such as TiAlSiN and ZrAlN, are not oxidation resistant independently on their chemical composition. Indeed, the columnar boundaries serve as oxygen diffusion channels. Conversely, a coating with a nanocomposite structure, such as Al-rich TiAlSiN, has an abrupt interface with the oxide grown on its top and no penetration of oxygen into the structure is observed
Symetryzacja pola magnetycznego cyklotronu AIC-144
No full textThe cyclotron AIC-144, currently used in proton radiotherapy of eye melanoma, is located in the Institute of Nuclear Physics in Cracow. The efficiency of protons deflection of this cyclotron, after elements of pole tip were precisely installed therein in 2006, amounted to 10%. Several months later micromoves of pole tip elements and decline of effectiveness of proton beams deflection were observed. Attempts to restore previous state led to partial success. The efficiency of deflection was still much lower than the one obtained in 2006 and amounted to 3%. The aim of this paper is to verify the hypothesis about deterioration of magnetic field symmetry in the area of acceleration and to correct the field by introducing micromoves into pole tip elements, under control of magnetic field mapping. The survey has confirmed significant asymmetry in the magnetic field within the acceleration area. After precise correction of the position of pole tip elements essential symmetry improvement was achieved. The correction was successful and after activating the cyclotron the efficiency of deflection reached 12%
Test of the European Transport Solver in the frame of Integrated Tokamak Modelling
No full textThe 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.This research was carried out under European Fusion Development Agreement (EFDA) work programs: WP09-ITM-IMP3-T1,WP10-ITM-IMP3-ACT1 and WP11-ITM-IMP3-ACT1, sponsored partly by the MNiSzW (Polish Ministry of Science and Higher Education) decisions No. 1468/7.PR-EURATOM UE/2010/7, No. 2058/7.PR-EURATOM/2011/2
The application of selected neutron scattering techniques to the study of short range order in soft matter
No full textSymulacje numeryczne odpowiedzi głębokościowej sondy NNTE w formacjach cienkowarstwowych nachylonych do osi odwiertu. Założenia i obliczenia wstępne metodą Monte Carlo
No full textBasic assumptions for calculation of well-logging profiles, expected from measurements of the neutron logging tools (type of NNTE) are presented. The report includes also results of the first tests and calculations. The NNTE tool responses were simulated using MCNP - the well-known Monte Carlo code. The general model consists of a huge rock, intersected by a borehole. A thin, flat rock layer of different lithology crosses that huge rock under an angle to the borehole. Numerous combinations of the model parameters - various porosities and neutron absorption cross-sections of the rocks as well as different layer thicknesses and angles - have been considered. The final results should be instantly useful for elaboration of the well-logging interpretation procedures for directional drillings, where the rock layers are usually sloped, or even highly inclined to the borehole axis
Strong and electromagnetic effects in peripheral nucleus-nucleus collisions at SPS energies
No full textThis paper deals with low momentum transfer (“soft”) hadronic interactions which build up most of the total cross section in high energy collisions of hadrons or atomic nuclei. The quantitative features of these interactions cannot be predicted on the basis of the present theory of strong interactions, Quantum Chromodynamics. The understanding of these processes relies therefore mostly on experimental knowledge. The main emphasis in this work is put on an attempt to extract new, quantitative information on the process of particle production in the reaction center-of-mass energy regime of several GeV per incoming hadron. This specifically concerns two issues: 1) the change induced in this process by transition from the elementary nucleon-nucleon collision to the nuclear heavy ion reaction, and 2) the possibility of obtaining novel information on the strong interaction on the basis of specific electromagnetic processes. Both issues are studied by means of a new, high quality experimental dataset on π meson production in peripheral lead-lead collisions. This dataset is compared with equally precise reference data on elementary interactions, allowing for the disentanglement of several effects present in the nuclear collision. One of these effects, the electromagnetic interaction between produced particles and the highly charged nuclear remnant (“spectator system”) is subsequently subject to a phenomenological analysis. The results of this analysis suggest that the latter electromagnetic effect can provide new information on the space-time evolution of the reaction.This work was supported by the Polish Ministry of Science and Higher Education
under grant no. N N202 078735
Charged particle multiplicity fluctuations and correlations in heavy-ion collisions in the PHOBOS experiment at RHIC
No full textThe Relativistic Heavy Ion Collider is the first accelerator in which beams of heavy
ions collide at an unprecedented energy of p sNN = 200 GeV. Collisions of Au nuclei result in creation of a system with extremely high energy density in which a new phase of matter, the strongly interacting Quark-Gluon Plasma, is formed. It manifests itself in suppression of partons with very high transverse momenta and large elliptic flow. A
general overview of experimental signals of QGP creation is presented with an emphasis on results from fluctuation and correlation studies. In a system crossing a phase transition or passing near a critical point enhanced fluctuations that can be visible also in various correlation studies may appear. This work describes in detail the analyzes of multiplicity fluctuations and correlations performed by the PHOBOS Collaboration. They include a search for events with unusually high multiplicities or very large fluctuations of the angular particle density distribution. The results of correlation studies can be explained by production of particles in clusters, which are large and very wide in pseudorapidity. In the analysis of reconstruction of cluster parameters and in calculations of acceptance effects Simple Cluster Model is applied. The centrality dependence of correlations suggests that they can not be described as decays of heavy resonances only, thus theWounded Nucleon Model is used to explain these correlations. It is shown that in this model the correlations are partly due to fluctuations of the number of wounded nucleons and that the Wounded Nucleon Model predicts them better than other models. The more technical aspects of the heavy-ion collisions studies are also described. There is some information on the RHIC accelerator complex and the experiments measuring Au + Au collisions, with a detailed discussion of the PHOBOS detector. In addition to results on multiplicity and charged particle pseudorapidity distributions, the multiplicity reconstruction methods are presented. Several methods of the vertex reconstruction applied in the PHOBOS experiment are discussed, including a novel algorithm based on hits in a single layer of silicon sensors. The system of PHOBOS Monte Carlo simulations and a report on its outcome are presented