Fast neutron activation analysis (FNAA) offers a new way to determine the bulk composition of Heusler alloys. Fast neutrons penetrate deep in the alloys, allowing to quantify the bulk elemental composition thanks to the characteristic gamma-rays emitted by the excited elements. In this work, a fast neutron generator (MP320) and a low-background high-efficiency well-type Ge gamma spectrometer are used to quantify the amount of Mn, Fe, Al, Si, and Sn in manufactured Heusler alloys. The alloy bulk composition is compared with the surface composition (micrometer depth range) obtained by classical energy dispersive X-ray analysis, demonstrating the interest of FNAA.

We investigate the isotopes of Se, Zr, Mo and Nd in the regions with N = 40, 60 and 90, where a first-order shape / phase transition, from spherical to deformed, can be observed. The signs of phase transitional behavior become evident by examining structure indicators, such as certain energy ratios and B(E2) transition rates and, in particular, how they evolve with neutron number. Microscopic mean-field calculations using the Skyrme-Hartree-Fock + Bardeen-Cooper-Schrieffer framework also reveal structural changes when considering the evolution of the resulting potential energy curves as functions of deformation. Finally, macroscopic calculations, using the Algebraic Collective Model, specifically for 74Se, 102Mo and 150Nd, after fitting its parameters to experimental spectra, result in potentials that resemble some of the potentials proposed in the framework of the Bohr Hamiltonian to describe shape transitions in nuclei. A more detailed account can be found in [1].

The present study is devoted to the Mn 2.4 Fe 0.8 Al 0.8 and Mn 2 FeAl alloys prepared by induction melting and studied in their original and subsequently annealed states. The annealing was carried out at 773 K/100 h and 1073 K/100 h in the argon atmosphere. The microstructure, phase composition, magnetic properties, and atom arrangement are followed with regard to Mn content and annealing conditions. The scanning electron microscopy completed by the energy dispersive X-ray spectroscopy and neutron activation analysis has detected single-phase alloys with compositions close to the nominal ones. Their structure, analyzed by X-ray diffraction, was found to be primitive cubic beta -Mn with the lattice parameters of 0.6359(2) nm for Mn 2.4 Fe 0.8 Al 0.8 and 0.6339(1) nm for Mn 2 FeAl. The coherent potential approximation calculations and positron annihilation spectroscopy have allowed obtaining an overview to the arrangement of Mn, Fe, and Al atoms in the beta -Mn structure and formation of the open volume defects. It is shown that Mn atoms occupy predominantly 8c Wyckoff sites and remaining Mn, Fe and Al atoms occupy 12d sites in equal 1/3 proportion. The open volume defects, vacancies and vacancy clusters, occur in both alloys and both annealed states in a very low concentration. From the magnetic viewpoint, both alloys in the as -prepared state and after annealing at 773 K/ 100 h are paramagnetic at room temperature with transition to antiferromagnetic state at about 30 - 40 K. The ac susceptibility measurements have indicated spin glass nature of the Mn 2 FeAl alloys. The annealing at a higher temperature, 1073 K/100 h, has affected mainly Mn 2.4 Fe 0.8 Al 0.8 alloy manifesting a weak ferro-/ferrimagnetic contribution at room temperature contributing to a strong magnetic ordering below 42 K.

Monitoring and characterization of particle beams in wide -range is often necessary in research and many applications with particle accelerators. The quantitative measurement evaluation of composition especially of high -intensity beams are limited and can become a challenge with conventional methods especially with simplified instrumentation for ease of deployment. For purpose, we developed a novel technique based on high -resolution spectral -sensitive tracking of single particles scattered from the beam path by a thin foil. We use a compact radiation camera equipped with the semiconductor pixel detector Timepix3 together with dedicated Monte -Carlo simulations. Particle -event type discrimination and directional information are produced by the detector spectral tracking response together with particle -type resolving power derived from experimental calibrations. Directional- and spectral -sensitive components can be resolved in wide field -of -view. Quantification of the primary beam intensity is extrapolated by numerical calculations. Demonstration and evaluation of the technique are provided by measurements with 33 MeV protons from a light ion cyclotron accelerator. Scattered particles originating from the thin foil, the accelerator beam nozzle, and air space along the beam path are detected and evaluated.

In this paper we focus on three mass regions where first-order phase transitions occur, namely, for N = 40, 60, and 90. We investigate four isotopic chains (Se, Zr, Mo, and Nd) in the framework of microscopic Skyrme-Hartree-Fock+Bardeen-Cooper-Schrieffer calculations for 15 different parametrizations. The microscopic calculations show the typical behavior expected for first-order phase transitions. To find the best candidate for the critical point phase transition we propose different microscopic position and occupation indices calculated for positive-parity and negative-parity proton and neutron single-quasiparticle states around the Fermi level. The microscopic calculations are completed by macroscopic calculations within the algebraic collective model (ACM), and compared with the experimental data for 74Se, 102Mo, and 150Nd, considered to be the best candidates for the critical-point nuclei.

We investigate 15 different Skyrme-interaction parametrizations and apply them to the chains of Te, Xe, Ba, Ce, Nd, Sm, Gd, Dy, Er, and Yb isotopes beyond N = 78 to calculate theoretical binding energies within the mean-field approach based on density functional theory. Results of calculations are compared with available experimental data on binding energies and quadrupole deformation with the aim to find out which interaction is the most convenient for shape and structure studies of these isotopic chains.

Dosimetry cross sections are fundamental quantities necessary for neutron dosimetry using the neutron activation method. It is worth noting that the uncertainty in cross sections is the major source of uncertainty in calculational predictions using nuclear data in simulations thus, cross section validation is a key issue in any aims for refinement of any predictions. A small compact neutron generator is a promising tool for performing integral experiments and even for differential experiments. This paper deals with the measurement of the differential dosimetry cross sections using a small compact D-T neutron generator with 14.05 MeV neutron emission (10E8 n/s into 4pi). Achieving measurable activation at such a low flux field is allowed by using a larger amount of activation material placed in close measurement geometry during decay gamma measurement. The experimentally determined cross sections are in good agreement with the cross sections in the IRDFF-II dosimetry library. The comparison with other nuclear data libraries was performed as well. Its worth noting, the mean standard deviation in IRDFF-II library is about 4 %, while in case of other data libraries they are from 5.5 % - 7.5 %. This result can be understood as a validation of IRDFF-II using 14.05 MeV neutrons and also a confirmation of the applicability of small compact generators in the measurement of activation cross sections.

Fast neutron activation analysis has been applied to bulk carbon detection. DT-neutron generator emitting 14.1 MeV neutrons was used as a neutron source. Prompt 4.44 MeV gammas from the inelastic neutron scattering on carbon were detected using a 30% HPGe semiconductor gamma spectrometer shielded from the primary neutron beam. The sensitivity of the experimental setup is discussed. Keywords: Activation analysis; Fast neutrons; Gamma spectrometry.

We examined the response of the pixel detector Timepix3 with silicon sensor to well-defined fast neutron fields. Part of the pixel detector silicon sensor was additionally equipped with a neutron mask of distinct converter regions. The mask consists of separate thermal and fast neutron regions using 6 LiF and hydrogen (plastic) converters, respectively. Measurements were performed with mono-energetic fast neutrons produced at D-D and D-T sources from a Van de Graaff accelerator and a neutron generator, respectively. Data were collected with low background including measurements with moderator material to provide a thermalized neutron component. All the signals produced in the detector were analyzed and decomposed in terms of the spectral-tracking response of the pixel detector. The effect of the fast and thermal components of the neutron converter were determined and compared with direct interactions in the silicon sensor which are significant and can be dominant for fast neutrons. We identify and classify the neutron-induced tracks in terms of the broad-type particle-event track classes. A partial overlap is unavoidable with tracks from direct detection of other radiations in particular protons and low-energy light ions as well as X rays. This will limit the neutron-event discrimination in mixed-radiation fields. The detection response according sensor-mask region was examined and calibrated for the investigated neutron fields. The neutron detection efficiency is selectively derived for the detector particle-event classes. This approach enables to enhance the neutron-discrimination and suppress background and unwanted events. This work enables to extend the response matrix of the detector for broad-type radiations to include neutrons both fast and thermal. The results serve to enhance the sensitivity and determine the neutron component in unknown and mixed-radiation fields such as outer space and particle radiotherapy environments.

We present an MCNP analysis of optimal gamma-detector shielding materials and their thicknesses for 14 MeV D-T neutron generator for detection of light elements by prompt gamma ray neutron activation analysis. Tungsten seems to be the best choice for the primary neutron-beam shielding of a minimum thickness, but copper and iron represent an economically acceptable alternative. To shield the gamma detector against gamma rays produced from neutron interactions in the laboratory walls another shielding made from lead is necessary.

Using D–T generators as a neutron source for precise measurements requests a well-known neutron spectrum and spatial distribution of neutron flux. It is important in cross section measurements as well as in deep penetration issues. Thus, it is very important not only to validate the fluence accurately but also accurately validate the neutron spectrum in various positions. Experimental validation of two different D–T neutron generator experiments was performed using proton recoil method. Measurements performed at different angles and neutron generator voltages show relatively good agreement with the calculations. Despite the poor resolution, it was shown that stilbene is usable for the measurement of neutron energy shift due to changes in deuteron voltage.

The magnetite and magnetite/ceria composites prepared by chemical procedures in various mutual ratios are exposed to calcination treatment in a temperature interval between 473 K and 1073 K. The combination of several experimental methods has provided detail structural, phase, and magnetic properties utilisable for selection of optimal compositions and calcination conditions from the viewpoint of degradation ability tested using parathion methyl and paraoxon. It is shown that the ceria content, selected between 5 wt.% and 50 wt.%, influences the magnetic properties. Its optimal amount was determined to be above 20 wt.% and the calcination temperature of 773 K when the highest rate constant, slightly above 0.06 min-1, was obtained for parathion methyl in acetonitrile using degradation test.

The spherical-to-deformed phase transition in cerium isotopes recently suggested to occur between 146Ce and 148Ce has been examined in the framework of the macroscopic algebraic collective model and two microscopic approaches, namely Skyrme-Hartree-Fock + Bardeen-Cooper-Schrieffer (BCS) calculations and the symmetry conserving configuration mixing method with Gogny energy density functionals applied also to the neighboring nuclei along the cerium isotopic chain. Possible spectral signatures of the phase transition are discussed in more details. The microscopic calculations predict octupole softness manifested by rather flat potential energy curves as a function of the octupole deformation parameter beta 3 for 146Ce and 148Ce and shape coexistence characterized by axially symmetric 0+ states, triaxial 2+ bands, and octupole deformation for the lowest 1- states.

We compare the specific activities of 137Cs and 40K in stipes and caps of three different common mushroom species (Xerocomus badius, Russula ochroleuca and Armillariella mellea) measured at the Czech Chernobyl hot spot in the Opava area (Silesia) and at a low-exposed site at the Beskydy mountains in 2011. The highest values of 137Cs were found in caps of Xerocomus badius and Russula ochroleuca in the Opava area (11.8 and 8.77 kBq/kg, respectively). The source of 137Cs was verified by the measurement of the 134Cs/137Cs ratio. Based on our results, we estimate an effective dose per year due to radiocaesium intake in the two investigated areas for Xerocomus badius, one of the most popular edible mushrooms in the Czech Republic. In 2011, the effective dose reached the maximum value of 0.102 mSv in the Opava area and 0.004 mSv at the low-exposed site at the Beskydy mountains. Therefore, it does not represent a significant risk for public health.

The 9.2 keV nuclear transition in 227Th was studied in the β−-decay of 227Ac by means of the internal conversion electron spectroscopy to clarify the spin-parity assignment of the ground state and the two lowest excited states of 227Th. The transition multipolarity was proved to be of mixed character M1 + E2 and the spectroscopic admixture parameter δ2(E2/M1)=0.695±0.248 (|δ(E2/M1)|=0.834±0.149) was determined. Nonzero value of δ(E2/M1) questioned the present theoretical interpretation of low-lying levels of 227Th. Calculations performed prefer the 1/2+, 3/2+, and 3/2+ sequence instead of the adopted 1/2+, 5/2+ and 3/2+ one for the 0.0, 9.2, and 24.3 keV levels, respectively.

This article focuses on description of two different neutron fields from linear and cylindrical Inertial Electrostatic Confinement (IEC) neutron generators. Both of these generators are well defined and commonly used. They use a deuterium-tritium reaction that produces neutrons with energies in the range 13 – 16 MeV, depending on the direction and the energy of the incoming deuterium nucleus. Two-parametric spectrometric system for neutron/gamma mixed fields NGA-01 was used to characterize neutron spectra in the proximity of generators. The cylindrical 45x45 mm stilbene scintillator was connected to this device using an active voltage divider. This way, we were able to measure neutron energies in the range 1 - 15 MeV while filtering out gamma radiation, even when counts per second is high. For the neutron spectrum calculation recoil spectra using deconvolution through maximum likelihood estimation was used. Measured neutron spectra have been compared with simulations realized via MCNP6. According to the theoretical prediction, these two types of generators produce different neutron fields. In case of the linear generator the target is very close to point located tritium bombarded by deuterons. Thus the neutron spectrum varies depending on the angle between the detector axis and the axis of the generator. Both experimental results and simulation show a shift of the neutron energy peak in pulse height histogram. For IEC type generators the neutron spectrum is more complicated. The shape and the position of the neutron energy peak depend heavily on the position of the detector. The most prominent effect is in the position in the plane perpendicular to the generator axis. In this case, the peak splits into two peaks that can be measured and distinguished. These results were verified by the diamond detector which was also used for characterization of the IEC type generator.

Atmospheric activity concentration of 7Be in the air was monitored during the period of one year from September 2015 to September 2016 at Ostrava, Czech Republic, with a two-day frequency that is shorter compared to a standard 7-day frequency of routine 7Be measurements. Simultaneously, relevant meteorological data (temperature, rainfall amount, precipitation particle size and speed, tropopause height, and PM10 concentrations) and the sunspot number were accumulated. Weighted linear regression analysis applied to the 7Be atmospheric activity concentration, the measured meteorological explanatory variables and the sunspot number revealed temperature as the most statistically significant explanatory variable. The tree model proved temperature as the most important explanatory variable and predicted the threshold value separating low and high temperature behavior of 7Be at about 13 °C (2-day average). A simple local two-layer (stratosphere and troposphere) atmospheric model was then applied to the data analysis. The model is able to fit the data for a larger accumulation period (6 days).

Excited states of the neutron-rich nucleus Ce-148 have been populated by neutron-induced fission of a U-235 target. Its electromagnetic decays were studied by means of gamma-ray coincidence spectroscopy with fast-timing capabilities. Lifetimes of the 2(1)(+) and 4(1)(+) states of Ce-148 were obtained and their E2 decay rates deduced. The B-4/2 = B(E2; 4(1)(+) -> 2(1)(+))/B(E2; 2(1)(+) -> 0(1)(+)) ratio indicates that Ce-148 is a transitional nucleus while the N = 88/90 shape phase transition evolves into a gradual change of nuclear deformation for proton numbers Z < 60.

Radium-bearing barytes (radiobarytes) have been known since the beginning of the 20th century. They are mainly found as precipitates of low-temperature hydrothermal solutions. In anthropogenic environments, they frequently occur as crusts on oil industry equipment used for borehole extraction, in leachates from uranium mill tailings, and as a by-product of phosphoric acid manufacturing. Recently, we recognized Ra-rich baryte as a precipitate in the water drainage system of a bituminous coal mine in the Czech part of the Upper Silesian Basin. The precipitate is a relatively pure baryte, with the empirical formula (Ba0.934Sr0.058Ca0.051Mg0.003)Σ1.046S0.985O4.000. The mean specific activity of 226Ra was investigated by the two-sample method and it equals 39.62(22) Bq/g, a level that exceeds known natural occurrences. The values for 228Ra and 224Ra are 23.39(26) Bq/g and 11.03(25) Bq/g. The radium content in the baryte is 1.071 ng/g. It is clear that the Ra-rich baryte results from the mixing of two different mine waters—brines rich in Ba, Sr, and isotopes 226Ra and 228Ra and waters that are affected by sulfide weathering in mine works. When this mixing occurs in surface watercourses, it could present a serious problem due to the half-life of 226Ra, which is 1600 years. If such mixing spontaneously happens in a mine, then the environmental risks will be much lower and will be, to a great, extent eliminated after the closure of the mine.

Clanek se zaměřuje na popis dvou různých neutronových poli linearniho neutronoveho generatoru (s pevným tercem s obsahem tritia) a valcoveho neutronoveho generatoru IEC (Inertial Electrostatic Confinement) s plynovou naplni. Oba generatory použivaji reakci D–T (Deuterium–Tritium), ktera produkuje neutrony s energii 14,1MeV (v rozmezi 13–16 MeV), v zavislosti na směru a energii přichoziho jadra deuteria. Spektrometrický system NGA-01 byl použit k charakterizaci neutronových spekter v blizkosti generatorů. Naměřena neutronova spektra byla porovnana se simulacemi realizovaný-mi pomoci výpocetniho kodu MCNP6. Podle teoreticke predikce tyto dva typy generatorů produkuji různa neutronove pole. U linearniho generatoru se neutronove spektrum měni v zavislosti na uhlu mezi podelnými osami detektoru a generatoru. Experimentalni výsledky i simulace souhlasně ukazuji posun energetickeho piku 14,1 MeV ve spektru. U generatorů typu IEC jsou tvar a poloha vrcholu neutronove energie take zavisle na pozici detektoru. Oproti linearnimu generatoru nedochazi k výraznemu energetickemu posunu piku ve spektru, ale při měřeni v rovině kolme na osu gene-ratoru se vrchol piku rozděli na dva vrcholy. To ukazalo měřeni provedene stilbenem a ověřeni pomoci diamantoveho detektoru, který byl take použit pro charakterizaci generatoru typu IEC.