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    Wyświetlanie 1-26 z 26
    Tytuł:
    Thermal and epithermal neutrons in the vicinity of the Primus Siemens biomedical accelerator
    Autorzy:
    Konefał, A.
    Dybek, M.
    Zipper, W.
    Łobodziec, W.
    Szczucka, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/148894.pdf
    Data publikacji:
    2005
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    biomedical accelerators
    thermal neutrons
    epithermal neutrons
    Opis:
    In this paper, the thermal and epithermal neutron fluence distributions in the vicinity of the Primus Siemens accelerator are presented. The measurements were carried out by the use of the neutron activation method for 15 MV X-rays and electron beams of 18 MeV and 21 MeV. From the radiation safety point of view for the hospital personnel, it is important to know the thermal and epithermal neutron fluence distribution in the vicinity of the accelerator because the neutrons interacting with atoms of a medium by various processes induce the activity of objects (accelerator, other apparatus etc.) and walls in the treatment room. The thermal and epithermal neutron capture, particularly, in high atomic number materials of the accelerator head can be a significant source of gamma radiation and it has to be taken into account for estimation of the work safety of the personnel. Values of the neutron fluence were normalized to the maximum photon (or electron) dose Dmax,gamma (e) measured at the central axis of therapeutic X-ray (or electron) beam in a water phantom. The thermal neutron fluences measured during the 15 MV X-ray emission varied between 1.1 × 10 5 n ź cm 2ź Gy -1 and 4.4 × 10 5 n ź cm -2ź Gy 1 whereas the epithermal neutron fluences ranged from 0.2 × 10 5 n ź cm 2ź Gy- 1 to 1.8 × 105 n ź cm -2ź Gy -1. In the case of electron beams, the neutron fluence measurements were performed only at the isocentre. The obtained thermal and epithermal neutron fluences were 1.2 × 10 4 n ź cm -2ź Gy -1 and 0.6 × 10 4 n ź cm -2ź Gy -1, respectively, for the 18 MeV electrons. In the the case of the 21 MeV electron beams the thermal neutron fluence was -2.0 × 10 4 n ź cm -2ź Gy -1 whereas the epithermal neutron fluence was 0.8 × 10 4 n ź cm -2ź Gy-1.
    Źródło:
    Nukleonika; 2005, 50, 2; 73-81
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Reconsideration of thermonuclear possibilities of Z-pinches
    Autorzy:
    Vikhrev, V. V.
    Powiązania:
    https://bibliotekanauki.pl/articles/147474.pdf
    Data publikacji:
    2001
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    fusion burn wave
    neutrons
    plasma focus
    Z-pinch
    Opis:
    The paper considers the Z-pinch as the basis for future thermonuclear fusion reactors. Experiments on Z-pinches always concern small and high temperature and a high density plasma regions that arise spontaneously in the Z-pinch neck. A burn wave might be initiated in the Z-pinch column if in this small plasma region a Lawson-like condition is fulfilled.
    Źródło:
    Nukleonika; 2001, 46, suppl. 1; 9-12
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nowa metoda pomiaru wilgotności gleby z wykorzystaniem neutronów kosmogeniczny
    New method for measuring soil moisture using cosmogenic neutrons
    Autorzy:
    Zreda, M.
    Nitychoruk, J.
    Chodyka, M.
    Świerczewska-Pietras, K.
    Zbucki, Ł.
    Powiązania:
    https://bibliotekanauki.pl/articles/2075270.pdf
    Data publikacji:
    2015
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    wilgotność gleby
    neutrony promieni kosmicznych
    metoda pomiarowa
    soil moisture
    cosmic-ray neutrons
    measuring method
    Opis:
    Taking advantage of the relation between the intensity of cosmic-ray neutrons measured in air above land surface and soil moisture, a new method was developed for measuring soil moisture at the scale of tens of hectares. The American-based project COSMOS produced and installed sensors to measure soil moisture and used them to monitor soil moisture across the USA. Sensors have also been installed in Europe, inclusing Poland. The purpose of this paper is to bring this new method to the Polish readers and to prepare the foundation for a fast introduction of this new technology to monitoring environmental moisture in Poland and adjacent areas.
    Źródło:
    Przegląd Geologiczny; 2015, 63, 4; 239--246
    0033-2151
    Pojawia się w:
    Przegląd Geologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Short Range Order in Polymers within Neutrons Eyeshot
    Autorzy:
    Zając, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810274.pdf
    Data publikacji:
    2009-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.41.+e
    61.43.-j
    61.05.fg
    Opis:
    The paper presents a short review of neutron scattering results obtained during investigation of short range order in bulk polymers. Neutron scattering proves exceptionally powerful in this type of study through (i) large penetration depth of bulk samples, (ii) isotope sensitivity, and (iii) the use of spin polarization technique. The examples provided deliver results that can hardly be obtained from e.g. X-ray diffraction.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 2; 594-598
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Critical Current Problems in Neutrons Irradiated HTc Multilayered Superconductors
    Autorzy:
    Sosnowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398613.pdf
    Data publikacji:
    2016-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.72.-h
    74.25.Wx
    74.25.Sv
    Opis:
    In the paper there is given an analysis of the critical current problems in irradiated multilayered high temperature oxide superconductors. Critical current for the direction of current flow inside the layers is investigated basing on analysis of the capturing interaction of pancake vortices with nanodefects, created by fast neutrons irradiation. Analysis of the pinning potential barrier formation is presented. From performed calculations of current-voltage characteristics fitted to measurements the inherent pinning centers concentration and their average dimensions were estimated. The case of perpendicular to layers current has been regarded too, taking into account the intrinsic Josephson junctions formation. The influence of nanodefects concentration on the Josephson penetration depth has been considered, whose length determines the Swihart velocity and current-voltage characteristics of junction.
    Źródło:
    Acta Physica Polonica A; 2016, 130, 2; 585-587
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Diagnostics and scaling of fusion-produced neutrons in PF experiments
    Autorzy:
    Schmidt, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/146622.pdf
    Data publikacji:
    2011
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    neutron emission
    plasma focus
    scaling laws
    neutron diagnostics
    nuclear fusion
    Opis:
    Neutrons from a plasma focus (PF) device operated in a deuterium gas, measured as a function of time, location and direction of emission, reveal quite a number of important parameters on fusion reactions occurring in the dense high-current phase of the experiment. In addition the determination of the energy spectra of the emitted neutrons is important for understanding the mechanisms taking place for the neutron production. Results of neutron measurements in large experiments such as the former POSEIDON experiment in Stuttgart and the PF-1000 experiment in Warsaw are presented. The neutron diagnostic methods that had been utilized include nuclear track detectors, plastic scintillators coupled to photomultipliers, activation measurements, time-of-flight methods as well as pinholes for spatial resolution of the neutron source. The well known scaling law according to which the neutron yield scales roughly as the square of the energy input or the fourth power of the current is discussed. Reasons for strong deviation from this law for high energies - known as the saturation effect - are still a subject of debate.
    Źródło:
    Nukleonika; 2011, 56, 2; 107-112
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Inverse Reaction Cross Sections for Some Charged Particles Using the Optical Model Parameters
    Autorzy:
    Ahmed, Rasha S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1193016.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Optical reaction cross-sections
    charged particles
    neutrons
    pre-equilibrium models
    Opis:
    p-nucleus, (_1^2)H-nucleus, (_1^3)H-nucleus, and (_2^4)He-nucleus inverse reaction cross sections have been determined using the optical model potentials in a wide range of target nuclei started from A=1 to A=232 using several incident particle energies ( E = 2, 8, 10, 20, and 40 MeV). In this work, a large number of optical model available parameters were used to calculate the inverse reaction cross section and compared to investigate the effect of the mass number and incident particle energy on the inverse reaction cross section. All the calculations were performed using MATHLAB programming language.
    Źródło:
    World Scientific News; 2016, 28; 72-83
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of Carrier Recombination in Si Heavily Irradiated by Neutrons
    Autorzy:
    Gaubas, E.
    Kadys, A.
    Uleckas, A.
    Vaitkus, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1813194.pdf
    Data publikacji:
    2008-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.72.J-
    61.82.Fk
    72.40.+w
    Opis:
    Variations of recombination lifetime, with fluence of the reactor neutrons from $10^{12}$ to $3×10^{16} n//cm^2$, in the magnetic field applied Czochralski grown Si samples are examined by the contactless transient techniques of the microwave probed photoconductivity and dynamic gratings. A nearly linear decrease in lifetime from few microseconds to about 200 ps within the examined range of neutron irradiation fluences was obtained. This dependence persists under relatively low (≤80°C) temperature heat treatments. Also, cross-sectional scans of lifetime depth-profiles were examined, which show rather high homogeneity of lifetime values within wafer thickness.
    Źródło:
    Acta Physica Polonica A; 2008, 113, 3; 829-832
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    EPR Investigations of Electrons and Neutrons Irradiated Cubic Boron Nitride
    Autorzy:
    Azarko, I.
    Ignatenko, O.
    Karpovich, I.
    Odzhaev, V.
    Kozlova, E.
    Zhukowski, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1400479.pdf
    Data publikacji:
    2013-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.-v
    81.05.Ea
    61.72.J-
    Opis:
    Microcrystals of cubic boron nitride powders synthesised under different conditions and further irradiated with neutrons and electrons have been investigated. It was found that some changes of the samples' paramagnetic properties depend on the electron irradiation dose. It was also shown that the initial boron type defects growth occurs under thermal neutron, as well as under fast neutrons irradiation. The nitrogen-containing defects concentration changes in a threshold manner.
    Źródło:
    Acta Physica Polonica A; 2013, 123, 5; 923-925
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determination of Polyolefine Based Composites Nanostructure Parameters by Very Cold Neutrons Scattering
    Autorzy:
    Kuznetsov, S.
    Dubnikova, I.
    Litvin, V.
    Meshkov, I.
    Shelagin, A.
    Udovenko, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1537817.pdf
    Data publikacji:
    2010-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.fm
    61.48.De
    82.35.Np
    Opis:
    Very cold neutrons (VCN) scattering method was used to study the morphology of polyolefine based nanocomposites. The nanocomposites were prepared by the melt mixing method. The special surface active additions and the fillers surface modification were used to improve the polymer-filler compatibility. The multiwalled carbon nanotubes (MWCNT), the calcium carbonate (CC) submicron particles and the layered natural mineral montmorillonite (MMT) nanoparticles were used as the fillers. The fractal structural model was used to describe the VCN scattering on the nanofillers agglomerates. It was shown by VCN scattering that the volume part of isolated MWCNTs in polypropylene (PP) based composites decreases with the increase of the filler loading, the density of MWCNT packing in agglomerates increases with the total volume nanotube concentration and decreases with the nanotube surface modification. It was revealed that the isolated CC particles are dominated in the CC/PP samples with low CC (5 vol.%) loading. It was shown that practically full MMT exfoliation within polyethylene (PE) matrix can be achieved by both polymerization exfoliation method and by melt mixing compounding with using special polar polymer additions.
    Źródło:
    Acta Physica Polonica A; 2010, 117, 5; 727-732
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On possible formulation of problems of a Dense Plasma Focus used in material sciences
    Autorzy:
    Gribkov, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/146787.pdf
    Data publikacji:
    2000
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    cumulative plasma streams
    dense plasma focus (DPF)
    electron beam
    ion beam
    material sciences
    neutrons
    X-rays
    Opis:
    The paper describes various possibilities at can be given by the use of dense plasma focus (DPF) device in material sciences. Main distinguishing features of such a device – availability of several different types of hard radiation and its high power flux density – determine the niche of applications of this type devices in the field. Some directions of materials investigation and treatment, which can be developed at present time, are discussed.
    Źródło:
    Nukleonika; 2000, 45, 3; 149-153
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preliminary determination of angular distribution of neutrons emitted from PF-1000 facility by indium activation
    Autorzy:
    Jednoróg, S.
    Szydłowski, A.
    Scholz, M.
    Paduch, M.
    Bienkowska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/146918.pdf
    Data publikacji:
    2012
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    plasma focus
    neutron activation technique
    plasma diagnostics
    Opis:
    This paper presents a new method applied to measure the angular neutron emission from Plasma Focus (PF) - type deuterium discharges performed within the PF-1000 facility. Neutrons were recorded by activation of especially optimized (mass and shape) indium samples with subsequent gamma spectrometry to measure the induced activity of the samples. The neutron fluence rate on every indium sample used was determined using neutron transport calculation and measured activity of the samples.
    Źródło:
    Nukleonika; 2012, 57, 4; 563-568
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetism in $UCo_{0.88}Ru_{0.12}Ge$ Studied by Polarized Neutrons
    Autorzy:
    Vališka, M.
    Pospíšil, J.
    Nénert, G.
    Stunault, A.
    Prokeš, K.
    Sechovský, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/1371426.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.70.Tx
    61.05.fm
    75.25.-j
    Opis:
    UCoGe is an archetype of coexisting weak itinerant 5f-electron ferromagnetism ($T_{C}$~3 K, $μ_{s}$=$0.03μ_{B}$/f.u.) and superconductivity ($T_{SC}$~ 0.6 K) at ambient pressure. The Ru substitution for Co leads to an initial sharp increase of the $T_{C}$ up to the maximum of $T_{C}$=8.5 K for x=0.12, increase of spontaneous magnetic moment and suppression of superconductivity. We have grown the $UCo_{0.88}Ru_{0.12}Ge$ single crystal and studied magnetization along the principal crystallographic axes. To see the microscopic background of these findings we performed a polarized neutron diffraction experiment on D3 diffractometer in ILL. We have found that the Co and U moments are parallel in $UCo_{0.88}Ru_{0.12}Ge$, in contrast to the antiparallel configuration in UCoGe. This is probably the reason of the spontaneous magnetization increase with Ru doping.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 330-331
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Biological efficiency of the Brookhaven Medical Research Reactor mixed neutron beam estimated from gene mutations in Tradescantia stamen hair cells assay
    Autorzy:
    Cebulska-Wasilewska, A.
    Schneider, K.
    Capała, J.
    Coderre, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/146139.pdf
    Data publikacji:
    2000
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    neutrons
    relative biological efficiency
    Tradescantia
    Opis:
    The relative biological effectiveness of low energy neutrons for the induction of various abnormalities in Tradescantia stamen hair mutation (Trad-SH) assay was studied using two clones (T-4430 and T-02), heterozygous for flower color. Dose response relationships for gene mutations induced in somatic cells of Trad-SH were investigated after irradiation with a mixed neutron beam of the Brookhaven Medical Research Reactor (BMRR), currently used in a clinical trial of boron neutron capture therapy (BNCT) for glioblastoma. To establish the RBE (relative biological effectiveness) of the BMRR beam in the induction of various biological end-points in Tradescantia, irradiation with various doses of g-rays was also performed. After irradiation all plants were cultivated several days at Brookhaven National Laboratory (BNL), the transported to Poland for screening the biological end-points. Due to the post-exposure treatment, all plants showed high levels of lethal events and alteration of the cell cycle. Plants of clone 4430 were more reactive to post-treatment conditions, resulting in decreased blooming efficiency that affected the statistics. Slope coefficients estimated from the dose response curves for gene mutation frequencies allowed the evaluation of ranges for the maximal RBE values of the applied beam vs. g-rays as 6.0 and 5.4 for the cells of T-02 and T-4430, respectively. Estimated fraction of doses from neutrons and corresponding biological effects for the clones T-02 and T-4430 allowed to evaluate the RBE values for neutrons part in the beam as 32.3 and 45.4, respectively.
    Źródło:
    Nukleonika; 2000, 45, 2; 115-119
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Studies of Plasma-Focus discharges within the PF-360 facility equipped with needle D2O-ice target
    Autorzy:
    Baranowski, J.
    Jakubowski, L.
    Sadowski, M.
    Zebrowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/147583.pdf
    Data publikacji:
    2001
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    cryogenic target
    current sheath
    neutrons yield
    plasma focus
    X-ray
    Opis:
    The paper describes a new technique which has been investigated in order to overcome the neutron saturation effect and to increase the neutron yield from the plasma-focus (PF) discharges [1]. The PF-360 experimental facility was constructed at the Andrzej Soltan Institute for Nuclear Studies (IPJ) in Swierk, Poland in the late 70s [4, 5]. Recently in order to improve the neutron yield from the PF-360 machine, it was proposed to use a cryogenic deuterium target, which might be placed within the plasma-focus region. For this purpose, we have been made a needle-like cryogenic target covered with a thin „heavy-ice“ layer. A considerable increase in the average neutron yield (from 1.7×1010 to about 2.2×1010 neutrons/shot) has been achieved for 122 kJ PF discharges when the needle target top was placed at a distance of about 100 mm from the electrode ends.
    Źródło:
    Nukleonika; 2001, 46, suppl. 1; 69-71
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical optimisation of the fission-converter and the filter/moderator arrangement for the Boron Neutron Capture Therapy
    Autorzy:
    Tracz, G.
    Dąbkowski, L.
    Dworak, D.
    Pytel, K.
    Woźnicka, U.
    Powiązania:
    https://bibliotekanauki.pl/articles/148388.pdf
    Data publikacji:
    2003
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    BNCT
    fission converter
    Fluka
    MCNP
    Monte Carlo
    neutrons
    Opis:
    The paper presents results of the numerical modelling of the fission-converter-based epithermal neutron source designed for a BNCT (Boron Neutron Capture Therapy) facility to be located at the Polish research nuclear reactor MARIA at Świerk. The unique design of the fission converter has been proposed due to a specific geometrical surrounding of the reactor. The filter/moderator arrangement has been optimised in order to moderate fission neutrons to epithermal energies and to get rid of both fast neutrons and photons from the therapeutic beam. The selected filter/moderator set-up ensures both the high epithermal neutron flux and the suitably low level of beam contamination. The elimination of photons originated in the reactor core is an exceptional advantage of the proposed design. It brings one order of magnitude lower gamma radiation dose than the permissible dose in such a type of therapeutic facility is required. The MCNP and FLUKA codes have been used for the computations.
    Źródło:
    Nukleonika; 2003, 48, 4; 177-185
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effectiveness of fast neutrons irradiation for the stimulation and induction of genetic changes in soybean [Glycine max L.Merrill] genome
    Autorzy:
    Sodkiewicz, T.
    Sodkiewicz, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/25532.pdf
    Data publikacji:
    1999
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Tematy:
    Warszawska cultivar
    irradiation
    stimulation
    fast neutron
    effectiveness
    soybean
    mutagenesis
    genetic change
    Glycine max
    genome
    Źródło:
    International Agrophysics; 1999, 13, 4
    0236-8722
    Pojawia się w:
    International Agrophysics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pulse shape discrimination of neutrons and gamma rays using kohonen artificial neural networks
    Autorzy:
    Tambouratzis, T.
    Chernikova, D.
    Pzsit, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/91759.pdf
    Data publikacji:
    2013
    Wydawca:
    Społeczna Akademia Nauk w Łodzi. Polskie Towarzystwo Sieci Neuronowych
    Tematy:
    shape
    neutron
    discrimination
    gamma rays
    Kohonen artificial neural networks
    ANNs
    linear vector quantisation
    LVQ
    self-organizing map
    SOM
    pulse shape discrimination
    PSD
    Opis:
    The potential of two Kohonen artificial neural networks (ANNs) - linear vector quantisation (LVQ) and the self organising map (SOM) - is explored for pulse shape discrimination (PSD), i.e. for distinguishing between neutrons (n’s) and gamma rays (’s). The effect that (a) the energy level, and (b) the relative size of the training and test sets, have on identification accuracy is also evaluated on the given PSD dataset. The two Kohonen ANNs demonstrate complementary discrimination ability on the training and test sets: while the LVQ is consistently more accurate on classifying the training set, the SOM exhibits higher n/ identification rates when classifying new patterns regardless of the proportion of training and test set patterns at the different energy levels; the average time for decision making equals ˜100 μs in the case of the LVQ and ˜450 μs in the case of the SOM.
    Źródło:
    Journal of Artificial Intelligence and Soft Computing Research; 2013, 3, 2; 77-88
    2083-2567
    2449-6499
    Pojawia się w:
    Journal of Artificial Intelligence and Soft Computing Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Zastosowanie neutronowej analizy aktywacyjnej NAA do identyfikacji materii pochodzenia kosmicznego na Ziemi
    Application of Neutron Activation Analysis for identification of cosmic matter on Earth
    Autorzy:
    Tymiński, Zbigniew
    Mysłek-Laurikainen, Bogumiła
    Powiązania:
    https://bibliotekanauki.pl/articles/1032679.pdf
    Data publikacji:
    2009
    Wydawca:
    Polskie Towarzystwo Meteorytowe
    Tematy:
    NAA
    classification of meteorites
    impact craters
    meteorites
    neutron activation analysis
    neutrons
    γ spectrometry
    Opis:
    Neutron activation analysis (NAA) is an analytical method based on the measurement of characteristic radiation from radionuclides formed by neutron irradiation of the material of interest. The most suitable source of neutrons for NAA is a research reactor. The neutron activation analysis has been found to be extremely useful in the determination of trace and minor elements in geological and extraordinary samples. The method is non-destructive, giving many advantages, which are described. Measured abundances of the elements in meteorites, from major constituents down to those appearing only in trace amounts, provide information important for the theories of the origin and history of the Solar System.
    Źródło:
    Acta Societatis Metheoriticae Polonorum; 2009, 1; 97-100
    2080-5497
    Pojawia się w:
    Acta Societatis Metheoriticae Polonorum
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Rapid production of 18F fluoride from 2-fluoroaniline via the 19F(n,2n)18F reaction using 14 MeV neutrons
    Autorzy:
    Mikołajczak, R.
    Staniszewska, J.
    Mikołajewski, S.
    Rurarz, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/147126.pdf
    Data publikacji:
    2002
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    chemical and production yields
    fluorine-18
    radiochemical separation
    (n,2n) reaction cross section
    Opis:
    No carrier-added 18F fluoride was produced via the 19F(n,2n)18F reaction by 14 MeV neutron irradiation of 2-fluoroaniline and subsequent extraction of the produced 18F fluoride ion with water. The fluoride was then purified by liquid chromatography on a Chromabond-NO2 column. The time required for all chemical procedures was about 1 h. The average chemical separation yield was about 70%. The 18F activity obtained after 3 hours of irradiation at a flux rate of 108 n cm-2s-1 after a necessary 20-min delay was equal to several kBq per gram of fluorine in a 2-fluoroaniline sample, in accordance with the theoretically expected value. Improvement of the 18F production yield can be achieved by increasing neutron fluxes. Neutron generators with 14 MeV neutron fluxes of the order of 1010 n cm-2s-1 can produce tens MBq of 18F, sufficient for whole-day work in biomedical applications. Our results show that 14 MeV neutron irradiation of 2-fluoroaniline is a low cost alternative for the production of this nuclide in the countries which do not posses either cyclotrons or electron linear accelerator facilities.
    Źródło:
    Nukleonika; 2002, 47, 1; 13-18
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fusion 2050 : European and Polish Perspective
    Autorzy:
    Romaniuk, R. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/226588.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    European research programs
    7FP
    accelerator science and technology
    large research infrastructures
    JET
    ITER
    IFMIF
    DEMO
    nuclear fusion
    thermonuclear power engineering
    DT fusion
    Neutrons
    aneutronic technologies
    inertial fusion
    tokomak
    stellarator
    fusion reactor
    tritium
    electronics for fusion
    Opis:
    Fusion, in all its varieties, is a very current subject of science and technology. The results of strongly exothermic reaction of thermonuclear fusion between nuclei of deuterium and tritium are: helium nuclei and neutrons, plus considerable kinetic energy of neutrons of over 14 MeV. DT nuclides synthesis reaction is probably not the most favorable one for energy production, but is the most advanced technologically. More efficient would be possibly an aneutronic fusion. The EU by its EURATOM agenda prepared a Road Map for research and implementation of Fusion as a commercial method of thermonuclear energy generation in the time horizon of 2050. The milestones on this road are tokomak experiments JET, ITER and DEMO, and neutron experiment IFMIF. There is a hope, that by engagement of the national government, and all research and technical fusion and plasma communities, part of this Road Map may be realized in Poland. The infrastructure build for fusion experiments may be also used for material engineering research, chemistry, biomedical, associated with environment protection, power engineering, security, etc. Construction of such research and industrial accelerator and tokomak infrastructure may have potentially a profound meaning for the development of science and technology in Poland.
    Źródło:
    International Journal of Electronics and Telecommunications; 2014, 60, 1; 95-101
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Peculiarities of neutron interaction with boron containing semiconductors
    Autorzy:
    Didyk, A. Y.
    Hofman, A.
    Szteke, W.
    Hajewska, E.
    Vlasukova, L. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/148104.pdf
    Data publikacji:
    2009
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    semiconductors
    thermal neutrons
    point defects
    vacancies
    damage concentration
    thermal neutron fluence
    cross-section of damage creation
    fission fragments
    lithium
    helium
    alfa-particles
    diffusion of impurities
    homogeneity of damage and active impurities
    Opis:
    Abstract. The results of point defect creation calculation in B4C, BN and BP semiconductor single crystals irradiated in the fast neutron reactor IBR-2 are presented. It has been shown that during the thermal neutron interaction with light isotope boron atoms (10B) the damage creation by means of fission nuclear reaction fragments (alfa-particles and 7Li recoil nuclei) exceeds the damage created by fast neutrons (En greater than 0.1 MeV) by more than two orders of value. It has been concluded that such irradiation can create a well developed radiation defect structure in boron-containing crystals with nearly homogeneous vacancy depth distribution. This may be used in technological applications for more effective diffusion of impurities implanted at low energies or deposited onto the semiconductor surface. The developed homogeneous vacancy structure is very suitable for the radiation enhanced diffusion of electrically charged or neutral impurities from the surface into the technological depth of semiconductor devices under post irradiation treatment.
    Źródło:
    Nukleonika; 2009, 54, 3; 163-168
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Neutron emission parameters from the collapse of the condensed Z-pinch
    Autorzy:
    Anan'ev, S. S.
    Bakshaev, Y. L.
    Bryzgunov, V. A.
    Chernenko, A. S.
    Dan'ko, S. A.
    Kazakov, E. D.
    Klír, D.
    Korolev, V. D.
    Smirnova, E. A.
    Ustroev, G. I.
    Vikhrev, V. V.
    Powiązania:
    https://bibliotekanauki.pl/articles/146662.pdf
    Data publikacji:
    2012
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    neutrons
    energy distribution
    fast Z-pinch
    Opis:
    The parameters of neutron emission from the neck of the condensed Z-pinch, were measured at an S-300 installation (2 MA, 100 ns). Profiled loads with central parts made from microporous deuterated polyethylene (with a density of 100 mg/cm3) were used in the experiments. Neutron emission parameters were measured by the time-of-flight (TOF) method. Neutrons were registered using four flight bases with 10 scintillation detectors which were placed at two axial and two radial directions. It was found that the mean neutron energy, determined by the TOF method, turned out to be anisotropic. The average energy of neutrons emitted along the axis towards the cathode, was shifted to higher energy (2.6-2.8 MeV) and the average energy of neutrons emitted towards the anode, was shifted to lower energy (2.1-2.3 MeV) compared to the d-d reaction neutron energy 2.45 MeV. The average energy of neutrons, emitted in two opposite radial directions, was close to 2.45 MeV. The half-width of the energy distributions reconstructed for all directions was 400-500 keV. The analysis of the experimental results demonstrated that the found phenomena could be explained by a slowly decaying high energy tail in the energy distribution of colliding deuterons. The maximal neutron yield was of 6 x 109.
    Źródło:
    Nukleonika; 2012, 57, 3; 333-336
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Measurements of doses from photon beam irradiation and scattered neutrons in an anthropomorphic phantom model of prostate cancer: a comparison between 3DCRT, IMRT and tomotherapy
    Autorzy:
    Kowalik, A.
    Jackowiak, W.
    Malicki, J.
    Skórska, M.
    Adamczyk, M.
    Konstanty, E.
    Piotrowski, T.
    Polaczek-Grelik, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/146348.pdf
    Data publikacji:
    2017
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    3DCRT
    IMRT
    low doses
    neutron doses
    thermoluminescent detectors (TLD)
    tomotherapy
    Opis:
    The rapid development of new radiotherapy technologies, such as intensity modulated radiotherapy (IMRT) or tomotherapy, has resulted in the capacity to deliver a more homogenous dose in the target. However, the higher doses associated with these techniques are a reason for concern because they may increase the dose outside the target. In the present study, we compared 3DCRT, IMRT and tomotherapy to assess the doses to organs at risk (OARs) resulting from photon beam irradiation and scattered neutrons. Material and methods. The doses to OARs outside the target were measured in an anthropomorphic Alderson phantom using thermoluminescence detectors (TLD 100) 6Li (7.5%) and 7Li (92.5%). The neutron fluence rate [cm–2·s–1] at chosen points inside the phantom was measured with gold foils (0.5 cm diameter, mean surface density of 0.108 g/cm3). Results. The doses [Gy] delivered to the OARs for 3DCRT, IMRT and tomotherapy respectively, were as follows: thyroid gland (0.62 ± 0.001 vs. 2.88 ± 0.004 vs. 0.58 ± 0.003); lung (0.99 ± 0.003 vs. 4.78 ± 0.006 vs. 0.67 ± 0.003); bladder (80.61 ± 0.054 vs. 53.75 ± 0.070 vs. 34.71 ± 0.059); and testes (4.38 ± 0.017 vs. 6.48 ± 0.013 vs. 4.39 ± 0.020). The neutron dose from 20 MV X-ray beam accounted for 0.5% of the therapeutic dose prescribed in the PTV. The further from the field edge the higher the contribution of this secondary radiation dose (from 8% to ~45%). Conclusion. For tomotherapy, all OARs outside the therapeutic field are well-spared. In contrast, IMRT achieved better sparing than 3DCRT only in the bladder. The photoneutron dose from the use of high-energy X-ray beam constituted a notable portion (0.5%) of the therapeutic dose prescribed to the PTV.
    Źródło:
    Nukleonika; 2017, 62, 1; 29-35
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Badania nad terapią BNCT w Polsce i na świecie
    Research on BNCT in Poland and in the world
    Autorzy:
    Knake, Natalia
    Maciak, Maciej
    Maliszewska-Olejniczak, Kamila
    Tymińska, Katarzyna
    Murawski, Łukasz
    Madejowski, Gaweł
    Wójciuk, Karolina
    Michaś, Edyta
    Wojtania, Grzegorz
    Kuć, Michał
    Dróżdż, Agnieszka
    Gryziński, Michał A.
    Powiązania:
    https://bibliotekanauki.pl/articles/986658.pdf
    Data publikacji:
    2019
    Wydawca:
    Indygo Zahir Media
    Tematy:
    BNCT
    hadronoterapia
    leczenie nowotworów
    związki boru
    neutrony
    hadron therapy
    cancer treatment
    boron compounds
    neutrons
    Opis:
    Przy Reaktorze MARIA w Narodowym Centrum Badań Jądrowych (NCBJ) powstaje stanowisko do badań nad terapią borowo-neutronową (BNCT). Terapia polega na napromienianiu nowotworu wiązką neutronów o odpowiednich parametrach po uprzednim podaniu pacjentowi związku boru, który w wyniku określonych mechanizmów gromadzi się głównie w komórkach rakowych. W wyniku reakcji 10B(n,α)7Li emitowane są cząstki jonizujące powodujące zniszczenie tylko tych komórek, w których zgromadzony jest bor [1]. Badania kliniczne prowadzone na świecie potwierdzają skuteczność metody, otwierając nowe perspektywy dla jej zastosowania w terapii konwencjonalnej.
    The stand for research on Boron Neutron Capture Therapy (BNCT) at the MARIA Reactor at the National Centre for Nuclear Research is being created. The therapy consists of irradiation of the tumour with a neutron beam with specific parameters after prior administration of the boron compound to the patient, which accumulates mainly in cancer cells as a result of specific mechanisms. As a result of 10B(n,α)7Li reaction, ionising particles are emitted and destroy only those cells, in which boron is accumulated. Clinical trials conducted in the world show relatively high efficiency of BNCT, opening new perspectives for its use in conventional therapy.
    Źródło:
    Inżynier i Fizyk Medyczny; 2019, 8, 4; 289-295
    2300-1410
    Pojawia się w:
    Inżynier i Fizyk Medyczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wielka pasja do tego, co najmniejsze. Życie i działalność Ludwika Wertensteina (1887–1945)
    Great passion for the smallest things: Life and work of Ludwik Wertenstein (1887–1945)
    Autorzy:
    Dolecki, Marcin
    Powiązania:
    https://bibliotekanauki.pl/articles/1396417.pdf
    Data publikacji:
    2020-12-31
    Wydawca:
    Polska Akademia Nauk. Instytut Historii Nauki im. Ludwika i Aleksandra Birkenmajerów
    Tematy:
    historia fizyki
    promieniotwórczość
    Pracownia Radiologiczna TNW im. Mirosława Kernbauma
    nieelastyczne rozpraszanie neutronów
    history of physics
    radioactivity
    Mirosław Kernbaum Radiological Laboratory of the Warsaw Scientific Society
    inelastic collisions of neutrons
    Opis:
    The aim of the article is to show the most important facts of the life and work of Professor Ludwik Wertenstein (1887–1945). He was a student of Maria Skłodowska-Curie and Ernest Rutheford, a de facto supervisor of the Mirosław Kernbaum Radiological Laboratory of the Warsaw Scientific Society (1914–1939) and a highly regarded science communicator. The main scientific achievement of Wertenstein was his discovery of inelastic collisions of neutrons in 1934.
    Źródło:
    Analecta. Studia i Materiały z Dziejów Nauki; 2020, 29, 2; 9-42
    1509-0957
    Pojawia się w:
    Analecta. Studia i Materiały z Dziejów Nauki
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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