Number of found documents: 419
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Preparation of ppHMDSO Thin Films in Capacitively Coupled RF Glow Discharges under Dusty Plasma Conditions
Homola, V.; Buršíková, V.; Kelar, L.; Kelarová, Š.; Stupavská, M.; Peřina, Vratislav
2018 - English
The deposition of organosilicone thin films from mixture of hexamethyldisiloxane (HMDSO) and oxygen by using capacitively coupled R.F. glow discharges under dusty plasma conditions was investigated. High resolution topography and mechanical property maps of the prepared films were acquired by using atomic force microscopy techniques. The chemical bond and composition of the deposited films were analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The mechanical properties of the films were studied using quasistatic as well as dynamic nanoindentation tests and their surface free energies were evaluated by means of contact angle measuring technique using several testing liquids exhibiting various surface tensions. The thermal stability of the films was studied using thermal desorption spectroscopy. Neural network modelling was used to study the effect of plasma parameters on the hardness of ppHMDSO films Keywords: Hexamethyldisiloxane; mechanical properties; oxygen; PECVD Available at various institutes of the ASCR
Preparation of ppHMDSO Thin Films in Capacitively Coupled RF Glow Discharges under Dusty Plasma Conditions

The deposition of organosilicone thin films from mixture of hexamethyldisiloxane (HMDSO) and oxygen by using capacitively coupled R.F. glow discharges under dusty plasma conditions was investigated. ...

Homola, V.; Buršíková, V.; Kelar, L.; Kelarová, Š.; Stupavská, M.; Peřina, Vratislav
Ústav jaderné fyziky, 2018

Stanovení prvkového složení drog neutronovou aktivační analýzou pro zjišťování jejich původu - studie proveditelnosti
Kučera, Jan; Kameník, Jan; Sabol, J.; Šesták, B.; Kolář, P.; Roman, M.
2018 - Czech
Analyzovali jsme pět vzorků heroinu a pět vzorků kokainu zachycených na území České republiky metodou instrumentální neutronové aktivační analýzy (INAA). Alespoň v jednom z analyzovaných vzorků heroinu jsme stanovili 16 stopových prvků, ve vzorcích kokainu se jednalo o 9 stopových prvků. Pozoruhodné rozdíly až v rozmezí několika řádů, jsme zjistili v obsazích prvků Na, Cl, Cr, Zn a Br, zejména ve vzorcích heroinu. Přesnost výsledků INAA jsme prokázali simultánní analýzou certifikovaného referenčního materiálu NIST SRM 1547 Peach Leaves. Výsledky stanovení stopových prvků v heroinu jsme porovnali s výsledky zahraničních autorů. Dosažené výsledky ukazují na vysoký potenciál metody INAA pro prvkovou charakterizaci drog za účelem zjištění jejich původu, způsobu výroby a čištění či způsobu ředění pro konečné uživatele. Pokládáme za účelné pokračovat v analýzách většího množství vzorků s konečným cílem vytvoření databáze prvkového složení vzorků zkonfiskovaných na území ČR, která by později mohla být rozšířena ve spolupráci se zahraničními protidrogovými a policejními orgány v mezinárodním měřítku. We analyzed five samples of heroine and five samples of cocaine seized in the Czech Repulic using instrumental neutron activation analysis (INAA). In the heroine speciments, we determined 16 trace elements in at least one of the samples analyzed, in the cocaine speciment, 9 trace elements could be determined. We have found remarkable differences, up to several orders of magnitude, in contents of the elements Na, Cl, Zna and Br, especially in the heroine samples. The accuracy of INAA results was proved by simultaneous analysis of a certified reference material NIST SRM 1547 Peach Leaves. The results of trace element determination in heroine samples are compard with those published by autors from abroad. The results obtained show a high potential of INAA for the drug elemental characteriaztion aimed at determination of their provenance, procedures used for their manufacturing and purification and cutting for the end users. The results achieved also suggest that it is desirable to analyze more samples with the final aim of establishing a database of elemental composition of drugs seized in the Czech Republic, which could possibly be extended later, in cooperation with foreign drug abuse and police bodies, at the international level. Keywords: heroine; cocain; INAA Available on request at various institutes of the ASCR
Stanovení prvkového složení drog neutronovou aktivační analýzou pro zjišťování jejich původu - studie proveditelnosti

Analyzovali jsme pět vzorků heroinu a pět vzorků kokainu zachycených na území České republiky metodou instrumentální neutronové aktivační analýzy (INAA). Alespoň v jednom z analyzovaných vzorků ...

Kučera, Jan; Kameník, Jan; Sabol, J.; Šesták, B.; Kolář, P.; Roman, M.
Ústav jaderné fyziky, 2018

Trojan horse method with neutrons induced reactions: The 17O(n,alpha)14C reaction
Guardo, G. L.; Spitaleri, C.; Lamia, L.; Gulino, M.; Tang, X.; Bucher, B.; Burjan, Václav; Couder, M.; Davies, P.; deBoer, R.; Fang, X.; Kroha, Václav; La Cognata, M.; Ma, C.; Mrázek, Jaromír; Mukhamedzhanov, A.; Notani, M.; O'Brien, S.; Pizzone, R. G.; Rapisarda, G. G.; Roberson, D.; Sergi, M. L.; Tan, W.; Wiescher, M.
2017 - English
The experimental study of the 17O(n,alpha)14C reaction has been performed in the energy range 0-350 keV. This reaction could play an important role in explaining heavy elements (s-process) nucleosynthesis in various astrophysical scenario. To over-come the practical problems arising from the neutrons production, a new application of the Trojan Horse Method has been recently suggested. Keywords: reaction study; nucleosynthesis; Trojan Horse Method Available at various institutes of the ASCR
Trojan horse method with neutrons induced reactions: The 17O(n,alpha)14C reaction

The experimental study of the 17O(n,alpha)14C reaction has been performed in the energy range 0-350 keV. This reaction could play an important role in explaining heavy elements (s-process) ...

Guardo, G. L.; Spitaleri, C.; Lamia, L.; Gulino, M.; Tang, X.; Bucher, B.; Burjan, Václav; Couder, M.; Davies, P.; deBoer, R.; Fang, X.; Kroha, Václav; La Cognata, M.; Ma, C.; Mrázek, Jaromír; Mukhamedzhanov, A.; Notani, M.; O'Brien, S.; Pizzone, R. G.; Rapisarda, G. G.; Roberson, D.; Sergi, M. L.; Tan, W.; Wiescher, M.
Ústav jaderné fyziky, 2017

Theranostic Mercury Part 1: A New Hg/Au Separation by a Resin Based Method
Walther, M.; Lebeda, Ondřej; Preusche, S.; Pietzsch, H.-J.; Steinbach, J.
2017 - English
The development of a fast and efficient method for Mercury/Gold separation is described as a necessary precondition for large scale production of theranostic mercury Hg-197(m). To achieve this, the application of so called LN resin (LaNthanides) was studied. The results confirm the applicability of this resin for Au/Hg separation by high efficiency, high separation factor and reproducibility. Keywords: cyclotron; Hg-197(m); LaNthanides Available at various institutes of the ASCR
Theranostic Mercury Part 1: A New Hg/Au Separation by a Resin Based Method

The development of a fast and efficient method for Mercury/Gold separation is described as a necessary precondition for large scale production of theranostic mercury Hg-197(m). To achieve this, the ...

Walther, M.; Lebeda, Ondřej; Preusche, S.; Pietzsch, H.-J.; Steinbach, J.
Ústav jaderné fyziky, 2017

On the scientific utilisation of low power research reactors
Mikula, Pavol; Strunz, Pavel
2017 - English
In our contribution we focus our attention on the scientific utilisation of the beam tubes at the low power research reactor LVR-15. Namely, it will be reported about the neutron scattering instrumentation development and the educational possibilities at the low power neutron sources. The feasibility of carrying out the methodology and instrumental development research at the low power neutron sources will be demonstrated on designs of several high resolution and good luminosity neutron scattering instruments exploiting Bragg diffraction optics. Some of them have been already realized e.g. for small angle neutron scattering studies or residual strain/stress measurements. As the mentioned instrumental development and testing can be carried out at the low power neutron sources, due to the much lower safety requirements in comparison with the medium and high flux sources, they offer excellent educational and training programmes in neutron scattering or imaging for students. Keywords: low power reactor; research with thermal neutrons; LVR-15 Available at various institutes of the ASCR
On the scientific utilisation of low power research reactors

In our contribution we focus our attention on the scientific utilisation of the beam tubes at the low power research reactor LVR-15. Namely, it will be reported about the neutron scattering ...

Mikula, Pavol; Strunz, Pavel
Ústav jaderné fyziky, 2017

Measurements and usage of cross sections of various (n,chi n) threshold reactions
Chudoba, Petr; Vrzalová, Jitka; Svoboda, Ondřej; Krása, Antonín; Kugler, Andrej; Majerle, Mitja; Suchopár, Martin; Wagner, Vladimír
2017 - English
Current trend in nuclear reactor physics is a transition from technologies using thermal neutrons to technologies utilizing fast neutrons. Unfortunately focus was put mainly on the thermal neutrons for a long time and lead to very good knowledge about this low energy region, but very scarce coverage of the high energy region. This means that there is a gap in the knowledge of excitation functions for higher energies. This gap spreads from 20 MeV up to 1 GeV and higher. This is exactly the energy region needed for description of advanced nuclear systems such as accelerator driven systems (ADS). Our group from Nuclear Physics Institute (NPI) of the CAS is a member of an international collaboration Energy & Transmutation of Radioactive Waste (E&T RAW). This collaboration focuses on ADS for many years. In order to measure neutron field within ADS models it is necessary to know excitation functions of reactions used to monitor the neutron field. In many cases there are almost no experimental data for suitable reactions. Worse and quite common case is that there are no data at all. Therefore we are also focusing on measurements of these data in order to fill the databases as well as to allow further improvements of codes for nuclear data calculations. Keywords: cross section; NPI; E&T RAW Available at various institutes of the ASCR
Measurements and usage of cross sections of various (n,chi n) threshold reactions

Current trend in nuclear reactor physics is a transition from technologies using thermal neutrons to technologies utilizing fast neutrons. Unfortunately focus was put mainly on the thermal neutrons ...

Chudoba, Petr; Vrzalová, Jitka; Svoboda, Ondřej; Krása, Antonín; Kugler, Andrej; Majerle, Mitja; Suchopár, Martin; Wagner, Vladimír
Ústav jaderné fyziky, 2017

Ion beams provided by small accelerators for material synthesis and characterization
Macková, Anna; Havránek, Vladimír
2017 - English
The compact, multipurpose electrostatic tandem accelerators are extensively used for production of ion beams with energies in the range from 400 keV to 24 MeV of almost all elements of the periodic system for the trace element analysis by means of nuclear analytical methods. The ion beams produced by small accelerators have a broad application, mainly for material characterization (Rutherford Back-Scattering spectrometry, Particle Induced X ray Emission analysis, Nuclear Reaction Analysis and Ion-Microprobe with 1 um lateral resolution among others) and for high-energy implantation. Material research belongs to traditionally progressive fields of technology. Due to the continuous miniaturization, the underlying structures are far beyond the analytical limits of the most conventional methods. Ion Beam Analysis (IBA) techniques provide this possibility as they use probes of similar or much smaller dimensions (particles, radiation). Ion beams can be used for the synthesis of new progressive functional nanomaterials for optics, electronics and other applications. Ion beams are extensively used in studies of the fundamental energetic ion interaction with matter as well as in the novel nanostructure synthesis using ion beam irradiation in various amorphous and crystalline materials in order to get structures with extraordinary functional properties. IBA methods serve for investigation of materials coming from material research, industry, micro- and nano-technology, electronics, optics and laser technology, chemical, biological and environmental investigation in general. Main research directions in laboratories employing small accelerators are also the preparation and characterization of micro- and nano-structured materials which are of interest for basic and oriented research in material science, and various studies of biological, geological, environmental and cultural heritage artefacts are provided too. Keywords: Ion beams; Electrostatic accelerators; Electronics; Nanostructures; Optics and optical physics Available at various institutes of the ASCR
Ion beams provided by small accelerators for material synthesis and characterization

The compact, multipurpose electrostatic tandem accelerators are extensively used for production of ion beams with energies in the range from 400 keV to 24 MeV of almost all elements of the periodic ...

Macková, Anna; Havránek, Vladimír
Ústav jaderné fyziky, 2017

The activation of W and Zr by deuterons at energies up to 20 MeV
Šimečková, Eva; Štefánik, Milan; Bém, Pavel; Mrázek, Jaromír; Novák, Jan
2017 - English
The proton and deuteron induced reactions are of a great interest for the assessment of induced radioactivity of accelerator components, target and beam stoppers. In order to investigate the important nuclides, we have carried up the irradiation experiments with the variable-energy cyclotron U-120 M of the NPI CAS ež. The production cross sections of the nuclides 179,181,182m,182,183,184m,184,186Re and 187W from reaction on natural W were investigated by deuteron beams of 20 MeV energy. A part of preliminary results of deuteron activation of natural Zr is also shown. The stacked-foil technique was utilized. The comparison of present results to data of other authors and to predictions of evaluated data libraries is discussed. Keywords: CANAM accelerators; proton and duteron induced reactions; cross section Available at various institutes of the ASCR
The activation of W and Zr by deuterons at energies up to 20 MeV

The proton and deuteron induced reactions are of a great interest for the assessment of induced radioactivity of accelerator components, target and beam stoppers. In order to investigate the important ...

Šimečková, Eva; Štefánik, Milan; Bém, Pavel; Mrázek, Jaromír; Novák, Jan
Ústav jaderné fyziky, 2017

Performance of self-developing radiography films in LVR-15's neutron beams
Šoltés, J.; Viererbl, L.; Klupák, V.; Vinš, M.; Michalcová, Božena
2017 - English
In the search for a suitable detector for demonstration neutron radiography measurements on the zero-power VR-1 training reactor at the Czech Technical University in Prague, some options were considered. Due to the reactor's low power and spatial limitations, an easy and practical solution had to be found. Self-developing films represent a flexible detection tool in x-ray imaging. Therefore, the goal of this study was to evaluate their potential for neutron detection. For this purpose, bare and converter covered films were studied in the thermal and epithermal neutron beams at the LVR-15 research reactor in Rez, Czech Republic. Keywords: neutron radiography; self-developing film; reactor LVR-15 Available at various institutes of the ASCR
Performance of self-developing radiography films in LVR-15's neutron beams

In the search for a suitable detector for demonstration neutron radiography measurements on the zero-power VR-1 training reactor at the Czech Technical University in Prague, some options were ...

Šoltés, J.; Viererbl, L.; Klupák, V.; Vinš, M.; Michalcová, Božena
Ústav jaderné fyziky, 2017

Neutron Diffraction and Acoustic Emission Measurement During Loading and Unloading of Magnesium Aluminium Binary Alloys
Čapek, Jan; Máthis, K.
2017 - English
The neutron diffraction and acoustic emission were measured during compression loading-unloading tests in randomly textured cast magnesium and magnesium 2 and 9 wt% aluminium binary alloys. The anelastic behavior and the change of twinned volume related to the detwinning phenomena can be observed during the unloading. The decrease of twinned volume fraction during unloading is most pronounced for Mg 9 wt% Al. Keywords: magnesium alloys; twinning; detwinning; neutron diffraction; acoustic emission Available at various institutes of the ASCR
Neutron Diffraction and Acoustic Emission Measurement During Loading and Unloading of Magnesium Aluminium Binary Alloys

The neutron diffraction and acoustic emission were measured during compression loading-unloading tests in randomly textured cast magnesium and magnesium 2 and 9 wt% aluminium binary alloys. The ...

Čapek, Jan; Máthis, K.
Ústav jaderné fyziky, 2017

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