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Proton and deuteron activation measurements at the NPI and future plans in SPIRAL2/NFS
Šimečková, Eva; Bém, Pavel; Mrázek, Jaromír; Štefánik, Milan; Běhal, Radomír; Glagolev, Vadim
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 as well as isotope production for medicine. In the present work, the deuteron-induced reaction cross sections on zinc were investigated by stacked-foil activation technique with deuteron beam of 20 MeV energy from the cyclotron U-120M of NPI CAS ež. Also the proton activation cross section measurement of iron is presented. The comparison of present results to data of other authors and to predictions of evaluated data libraries is discussed. The investigation shall continue for higher proton and deuteron energy interval 20-35 MeV at SPIRAL2/NFS facility using a charged particle irradiation chamber with pneumatic transport system to measure isotopes and isomers with half-lives in minutes-regions.
Keywords:
SPIRAL2/NFS; CANAM accelerators; cross section
Available at various institutes of the ASCR
Proton and deuteron activation measurements at the NPI and future plans in SPIRAL2/NFS
The proton- and deuteron-induced reactions are of a great interest for the assessment of induced radioactivity of accelerator components, target and beam stoppers as well as isotope production for ...
Position-Sensitive Coincidence Detection of Nuclear Reaction Products at the Prague Van-de-Graaff Accelerator
Granja, Carlos; Kraus, V.; Pugatch, V.; Kohout, Z.
2017 - English
In low-energy nuclear reactions of astrophysical interest or fusion studies the spatial-and time-correlated detection of two and more reaction products can be a valuable tool in studies of reaction mechanisms, resolving reaction channels and measuring angular distributions of reaction products. For this purpose we constructed a configurable array of position-sensitive detectors based on the hybrid semiconductor pixel detector Timepix. Additional analog-signal electronics provide self-trigger together with extended multi-device control and synchronized readout electronics by a customized control and coincidence unit. The instrumentation, developed and used for detection of fission fragments in spontaneous and neutron induced fission as well as in charged particle detection in neutron induced reactions, is being implemented for low-energy light-ion induced nuclear reactions. Application and demonstration of the technique with two Timepix detectors on p+p elastic scattering at the Van-de-Graaff (VdG) accelerator in Prague is given.
Keywords:
Van-de-Graaff; Timepix
Available at various institutes of the ASCR
Position-Sensitive Coincidence Detection of Nuclear Reaction Products at the Prague Van-de-Graaff Accelerator
In low-energy nuclear reactions of astrophysical interest or fusion studies the spatial-and time-correlated detection of two and more reaction products can be a valuable tool in studies of reaction ...
Numerical modeling of surface elastic wave scattering in polycrystalline materials
Grabec, Tomáš; Ryzy, M.; Verres, I. A.
2017 - English
Grain-boundary scattering of acoustic waves in polycrystalline materials is studied with analytical and numerical methods in the presented paper. In particular, the attenuation of Surface Acoustic Waves (SAWs) propagating through a polycrystalline microstructure is investigated. A three dimensional timedomain finite-element method (FEM) is utilized for the numerical simulation, whereby the granular microstructure is modeled by Voronoi tessellation. The resulting frequency-dependent attenuation coefficients are compared to an explicit analytical model.
Keywords:
grain boundary scattering; elastic wave; numerical modeling; polycrystalline material
Available at various institutes of the ASCR
Numerical modeling of surface elastic wave scattering in polycrystalline materials
Grain-boundary scattering of acoustic waves in polycrystalline materials is studied with analytical and numerical methods in the presented paper. In particular, the attenuation of Surface Acoustic ...
Residual stress determination by neutron diffraction in low-carbon steel wires with accumulated shear deformation
Rogante, M.; Mikula, Pavol; Strunz, Pavel; Zavdoveev, A.
2017 - English
Modern methods of severe plastic deformation (SPD) currently allow obtaining the ultrafine-grained (UFG) structure nearly in any material. In the manufacturing process of wire with UFG structure, a main restriction is the continuous drawing scheme in which this process occurs, thus it is important to consider the factors affecting the drawing efficiency. Despite the data on SPD steels such as strength, plasticity and conductivity, obtained by classical methodologies, further investigations are needed: a key information is the residual stresses (RS) status, and RS determination is an essential issue to improve knowledge of SPD effects. In this work, 15 wires samples made of low-alloyed quality structural steel Grade 08G2S GOST 1050 with accumulated shear deformation - as result of rolling with shear of the metal ingot and conventional wire drawing - have been investigated by neutron diffraction (ND). Results provide substantial data helping to evaluate the effect of shear deformation on RS of the considered steel, as well as additional support to complement the information already achieved by using the other characterization methodologies. Knowledge of the RS status can help developing a lowcarbon wire drawing technology with needed manufacturability and efficiency, playing a decisive role in the debugging of material selection and engineering design requirements.
Keywords:
Residual stresses; Neutron diffraction; Steel
Available at various institutes of the ASCR
Residual stress determination by neutron diffraction in low-carbon steel wires with accumulated shear deformation
Modern methods of severe plastic deformation (SPD) currently allow obtaining the ultrafine-grained (UFG) structure nearly in any material. In the manufacturing process of wire with UFG structure, a ...
Modifikace materiálů pro optiku, elektroniku a spintroniku iontovým svazkem – iontová implantace pomocí urychlovačů nebo laserem indukovaného plazmatu
Macková, Anna
2016 - Czech
Ion beam modification offers a broad field of the creating the new functional materials and nano-structures for optics, electronics, spintronics and other material branches. Using ions produced by ion accelerators or implanters\nmeans the usage of the monoenergetic beams for precise doped layer, nano-particles or cluster creation by varying the ion implantation specie versus matrix combination together with the implantation energy, ion flux etc. Recently\nappears the multienergetic ion implantation which is realized by using of the intense laser shot generating plasma from the specially designed targets, where the ions are accelerated and can be then implanted into the various\nmaterials. This contribution will present an overview and comparison of different ion beam modification techniques, plasma ion implantation will be also mentioned.
Keywords:
modification; materials; ion implantation
Available at various institutes of the ASCR
Modifikace materiálů pro optiku, elektroniku a spintroniku iontovým svazkem – iontová implantace pomocí urychlovačů nebo laserem indukovaného plazmatu
Ion beam modification offers a broad field of the creating the new functional materials and nano-structures for optics, electronics, spintronics and other material branches. Using ions produced by ion ...
Calibration and Exact Characterization of Aerosol Deposit colected by SDI Impactor
Havránek, Vladimír
2016 - English
Ion beam analytical methods as PIXE (Particle induced X-ray emission), PIGE (Particle induced gamma-ray emission) and RBS (Rutherford backscattering spectrometry) are frequently used for elemental analysis of different types of atmospheric aerosol samples in a form of aerosol deposits on thin plastic filters or foils (Alfassi and Peisach, 1991, Johansson and Campbell, 1988). An ideal sample for analysis is thin homogeneous aerosol deposit with known deposit area. However in practice such samples are rare. They are often thick (more than limit for thin target approximation i.e. larger then few hundred micrograms per square centimetres), of irregular shape and unknown deposit area. In such conditions all obtained elemental mass results should be corrected for apparent deposit thickness, deposit homogeneity and effective deposit area.
Keywords:
atmospheric aerosols; PIXE; RBS; calibration; elemental concentration
Available at various institutes of the ASCR
Calibration and Exact Characterization of Aerosol Deposit colected by SDI Impactor
Ion beam analytical methods as PIXE (Particle induced X-ray emission), PIGE (Particle induced gamma-ray emission) and RBS (Rutherford backscattering spectrometry) are frequently used for elemental ...
Vliv kryogenního mletí na homogenitu jódu v NIST SRM1548a Typical Diet
Kameník, Jan; Kučera, Jan
2016 - Czech
The reference material NIST SRM 1548a Typical Diet has a certified iodine mass fraction of 0.759±0.103 mg kg-1. The expanded uncertainty is rather large (relative value 13.6 %), thus the material does not provide strict requirements for quality control results. Milling of NIST SRM 1548a at the temperature of liquid nitrogen yielded free-flowing material. Iodine mass fraction in the original and cryo-ground materials was determined by epithermal neutron activation analysis (ENAA) and radiochemical neutron activation analysis (RNAA). The average and standard deviation from both methods was 0.73±0.03 mg kg-1 (20 values). The determined mass fraction was in a close agreement with the certified value of NIST SRM 1548a, thus iodine total content was not influenced by the milling procedure. In comparison to iodine mass fraction determined in the original NIST SRM 1548a 0.72±0.07 mg kg-1 (average ± standard deviation, 14 values), the standard deviation for cryo-ground material was considerably lower. The prepared quality control material sets up more stringent requirements on the validation and quality control procedures of the measurement of iodine mass fraction in such a composite food matrices. We believe that the iodine random inhomogeneity in the original NIST SRM 1548a is due to insufficient mixing of some iodine-rich component in the complex food matrices. Milling at the temperature of liquid nitrogen offers an effective option for production of future reference materials of this kind. The reference material NIST SRM 1548a Typical Diet has a certified iodine mass fraction of 0.759±0.103 mg kg-1. The expanded uncertainty is rather large (relative value 13.6 %), thus the material does not provide strict requirements for quality control results. Milling of NIST SRM 1548a at the temperature of liquid nitrogen yielded free-flowing material. Iodine mass fraction in the original and cryo-ground materials was determined by epithermal neutron activation analysis (ENAA) and radiochemical neutron activation analysis (RNAA). The average and standard deviation from both methods was 0.73±0.03 mg kg-1 (20 values). The determined mass fraction was in a close agreement with the certified value of NIST SRM 1548a, thus iodine total content was not influenced by the milling procedure. In comparison to iodine mass fraction determined in the original NIST SRM 1548a 0.72±0.07 mg kg-1 (average ± standard deviation, 14 values), the standard deviation for cryo-ground material was considerably lower. The prepared quality control material sets up more stringent requirements on the validation and quality control procedures of the measurement of iodine mass fraction in such a composite food matrices. We believe that the iodine random inhomogeneity in the original NIST SRM 1548a is due to insufficient mixing of some iodine-rich component in the complex food matrices. Milling at the temperature of liquid nitrogen offers an effective option for production of future reference materials of this kind.
Keywords:
SRM1548a Typical Diet; epithermal neutron activation analysis; radiochemical neutron activation analysis
Available at various institutes of the ASCR
Vliv kryogenního mletí na homogenitu jódu v NIST SRM1548a Typical Diet
The reference material NIST SRM 1548a Typical Diet has a certified iodine mass fraction of 0.759±0.103 mg kg-1. The expanded uncertainty is rather large (relative value 13.6 %), thus the material does ...
Study of fully automated analyzing system for the study of low-dose radiation effects on cellular radiobiology
Nagasaki, Y.; Matuo, Y.; Pachnerová Brabcová, Kateřina; Yasuda, N.
2016 - English
Study of fully automated analyzing system for the study of low-dose radiation effects on cellular radiobiology (poster)
Keywords:
storage facility; dosimetry; irradiation
Available at various institutes of the ASCR
Study of fully automated analyzing system for the study of low-dose radiation effects on cellular radiobiology
Study of fully automated analyzing system for the study of low-dose radiation effects on cellular radiobiology (poster)
PHASE EVOLUTION IN Ni-48 at.% TI SHAPE MEMORY ALLOY PREPARED BY SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS
Karlík, M.; Haušild, P.; Beran, Přemysl; Novák, P.; Čapek, J.; Kučera, V.; Kopeček, Jaromír
2015 - English
In Ni rich Ni–Ti alloys, various phases such as hexagonal Ni3Ti, cubic NiTi2 and rhombohedral Ni4Ti3 appear during heat treatment. The presence of these precipitates affects the shape memory effect and superelasticity in an important manner. In this paper we present a study of the phase evolution during annealing of the Ni–48at.%Ti shape memory alloy elaborated by self-propagating high-temperature synthesis (SHS). Morphology and crystallography of the phases were examined by means of light metallography, scanning electron microscopy (SEM), neutron and X-ray diffraction, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Besides the phases mentioned in the\nliterature, a Ni-rich phase with the composition near Ni3Ti2 stoichiometry and having a cubic symmetry was found. This phase develops from Ni4Ti3 particles during slow (furnace) cooling from the temperature of 1000 °C. Its particles have the form of thin platelets coherent with the (B2) NiTi matrix. The orientation relation is either cube-to-cube, [111]P || [115]B2 and (1-10)P || (1-10)B2 or [011]P || [011]B2 and (1-10)P || (1-41)B2.\n
Keywords:
NiTi shape memory alloy; neutron diffraction; phase analysis; light and electron microscopy
Available at various institutes of the ASCR
PHASE EVOLUTION IN Ni-48 at.% TI SHAPE MEMORY ALLOY PREPARED BY SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS
In Ni rich Ni–Ti alloys, various phases such as hexagonal Ni3Ti, cubic NiTi2 and rhombohedral Ni4Ti3 appear during heat treatment. The presence of these precipitates affects the shape memory effect ...
IMPEDANCE MEASUREMENT OF GAS SENSORS WITH NICKEL(II)-AND COPPER(II)-OXIDE ACTIVE LAYERS
Horák, Pavel; Khun, J.; Vrňata, M.; Bejšovec, Václav; Lavrentiev, Vasyl; Vacík, Jiří
2015 - English
Thin layers (90 nm) of nickel(II)- and copper(II)- oxide were deposited onto ceramic sensor substrates equipped with interdigital electrodes for signal reading. The deposition was carried out in two or three steps: (i) sputtering by means of Ar ion beam from pure (99.99%) metal targets, (ii) following thermal oxidation (400 degrees C for 5 h) in air, (iii) in some cases - sputtering of Pd catalyst to the surface. Then the impedance response of produced sensors (NiO, NiO+Pd, CuO, CuO+Pd) to 1000 ppm of hydrogen and 1000 ppm of methanol vapor was measured. Impedance measurements were performed in the frequency range from 40 Hz to 100 MHz. The obtained data were depicted in Nyquist representation (i.e. imaginary vs. real part of complex impedance). These diagrams have a character of one complete and one incomplete semicircle, each of them corresponding to a parallel RC-element. It was proved, that both NiO and CuO behave like p-type semiconductors; the sensor impedance increases on exposure to reducing gases. The best sensitivity was achieved on NiO+Pd sensor - during detection of hydrogen (1000 ppm) the real part of complex impedance measured at 40 Hz increased from 120 to 350 Omega.
Keywords:
gas sensors; impedance measurement; nickel(II) oxide and copper(II) oxide
Available at various institutes of the ASCR
IMPEDANCE MEASUREMENT OF GAS SENSORS WITH NICKEL(II)-AND COPPER(II)-OXIDE ACTIVE LAYERS
Thin layers (90 nm) of nickel(II)- and copper(II)- oxide were deposited onto ceramic sensor substrates equipped with interdigital electrodes for signal reading. The deposition was carried out in two ...
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