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Prompt Gamma Neutron Activation Analysis is a nuclear-based technique that can be used in explosives detection. It relies on bombarding unknown samples with neutrons emitted from a neutron source. These neutrons interact with the sample nuclei emitting the gamma spectrum with peaks at specific energies, which are considered a fingerprint for the sample composition. Analyzing these peaks heights will give information about the unknown sample material composition. Shielding the sample from gamma rays or neutrons will affect the gamma spectrum obtained to be analyzed, providing a false indication about the sample constituents, especially when the shield is unknown. Here we show how using deep neural networks can solve the shielding drawback associated with the prompt gamma neutron activation analysis technique in explosives detection. We found that the introduced end-to-end framework was capable of differentiating between explosive and non-explosive hydrocarbons with accuracy of 95% for the previously included explosives in the model development data set. It was also, capable of generalizing with accuracy 80% over the explosives which were not included in the model development data set. Our results show that coupling prompt gamma neutron activation analysis with deep neural networks has a good potential for high accuracy explosives detection regardless of the shield presence. [ABSTRACT FROM AUTHOR]

This article presents the results of the determination of element concentrations in biological and geological samples by using the Prompt Gamma Neutron Activation Analysis (PGNAA) facility that was installed at horizontal channel No. 4 of the Dalat research reactor. The biological standard sample Bovine Liver NBS 1577a and environmental standard sample Coal Fly Ash NBS 1633a were analyzed to verify the analytical ability of the facility. After that, the concentrations of N, K, Cl, Fe, Ca, Mn and B in biological samples and concentrations of K, Al, Si, Fe, Ca, Mn, Gd, Sm, Ti, and B in geological samples were determined in the framework of quality assurance and quality control programme at the Dalat Nuclear Research Institute. The analytical results indicated that this PGNAA facility can be used as a suitable instrumental tool to study in the fields of environment, biology and geology. [ABSTRACT FROM AUTHOR]

The prompt gamma neutron activation analysis (PGNAA) technology is an online nondestructive material analysis technology widely used in industries. In order to achieve real-time measurements, the gamma ray count rate should reach 400 kcps. Due to the limitation of the detector's decay time, the signal output from the detector is heavily piled up. Meanwhile, the industrial site has a temperature fluctuation of 0-50 °C, causing the peak drift in the energy spectrum. This paper presents a readout electronic system specified for PGNAA and proposes series of algorithms that are dedicated for the gamma-ray spectrometric system. The system can achieve a count rate of 400 kcps, and it overcomes poor resolution, spectral distortion, and peak position shift, which are caused by pulse pileups and temperature fluctuations. [ABSTRACT FROM AUTHOR]

We have developed and evaluated a new approach to fast neutron and neutron–gamma detection based on large-area multilayer composite heterogeneous detection media consisting of dispersed granules of small-crystalline scintillators contained in a transparent organic (plastic) matrix. Layers of the composite material are alternated with layers of transparent plastic scintillator material serving as light guides. The resulting detection medium—designated as ZEBRA—serves both as an active neutron converter and a detection scintillator which is designed to detect both neutrons and gamma quanta. The composite layers of the ZEBRA detector consist of small heavy-oxide scintillators in the form of granules of crystalline ZWO, BGO, GSO(Ce), and other materials. We have produced and tested the ZEBRA detector of sizes $100 \mathrm{mm} \times 100 \mathrm{mm} \times 41 \mathrm{mm}$ , and determined that they have very high efficiency of fast neutron detection (up to 49% or greater), comparable to that which can be achieved by large sized heavy-oxide single crystals of about $\varnothing 40 \times 80 \ \mathrm{cm}^3$ volume. We have also studied the sensitivity variation of fast neutron detection by using different types of multilayer ZEBRA detectors of 100-cm2 surface area and 41-mm thickness (with a detector weight of about 1 kg) and found it to be comparable to the sensitivity of a 3He-detector representing a total cross section of about 2000 cm2 (with a weight of detector, including its plastic moderator, of about 120 kg). The measured count rate in response to a fast neutron source of 252Cf at 2 m for the ZEBRA-GSO(Ce) detector of size $100 \ \mathrm{mm} \times100 \ \mathrm{mm} \times41 \ \mathrm{mm}$ was 2.84 Hz/ng of 252Cf isotope, and this count rate can be doubled by increasing the detector height (and area) up to $200\ \mathrm{mm} \times100 \ \mathrm{mm}$. In summary, the ZEBRA detectors represent a new type of high efficiency and low-cost large-area solid-state neutron detector that can be used for stationary neutron/gamma portals. They may represent an interesting alternative to expensive, bulky gas counters based on 3He or 10Bneutron detection technologies. [ABSTRACT FROM AUTHOR]

We analyse the chemical composition of the planetary nebula (PN) NGC 5315, through high-resolution (R ~ 40000) optical spectroscopy with Ultraviolet-Visual Echelle Spectrograph at the Very Large Telescope, and medium-resolution (R ~ 4800) near-infrared spectroscopy with Folded-port InfraRed Echellette at Magellan Baade Telescope, covering a wide spectral range from 0.31 to 2.50 μm. The main aim of this work is to investigate neutron (n)-capture element abundances to study the operation of the slow n-capture ('s-process') in the asymptotic giant branch (AGB) progenitor of NGC 5315. We detect more than 700 emission lines, including ions of the n-capture elements Se, Kr, Xe and possibly Br. We compute physical conditions from a large number of diagnostic line ratios, and derive ionic abundances for species with available atomic data. The total abundances are computed using recent ionization correction factors (ICFs) or by summing ionic abundances. Total abundances of common elements are in good agreement with previous work on this object. Based on our abundance analysis of NGC 5315, including the lack of s-process enrichment, we speculate that the most probable evolutionary scenario is that the progenitor star is in a binary system as hinted at by radial velocity studies, and interactions with its companion truncated the AGB before s-process enrichment could occur. However there are other two possible scenarios for its evolution, that cannot be ruled out: (i) the progenitor is a low-mass single star that did not undergo third dredge-up; (ii) the progenitor star of NGC 5315 had an initial mass of 3-5 M⊙, and any s-process enhancements were heavily diluted by the massive envelope during the AGB phase. [ABSTRACT FROM AUTHOR]

A 6Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-light single-crystal diffraction instruments at Spallation Neutron Source. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 104. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, six digital signal analysis methods of individual waveforms acquired from photomultiplier tubes were proposed using (i) charge integration, (ii) pulse-amplitude histograms, (iii) power spectrum analysis combined with the maximum pulse-amplitude, (iv) two event parameters (a1, b0) obtained from a Wiener filter, (v) an effective amplitude (m) obtained from an adaptive least-mean-square filter, and (vi) a cross-correlation coefficient between individual and reference waveforms. The NGD ratios are about 70 times those from the traditional PHA method. Our results indicate the NGD capabilities of neutron Anger cameras based on GS20 scintillators can be significantly improved with digital signal analysis methods. [ABSTRACT FROM AUTHOR]

The properties of the relative abundances of rapid and slow neutron-capture elements are studied using a catalog containing spectroscopic abundance determinations for 14 elements produced in various nuclear-synthesis processes for 90 open clusters. The catalog also contains the positions, ages, velocities, and elements of the Galactic orbits of the clusters. The relative abundances of both r-elements (Eu) and s-elements (Y, Ba, La, and Ce) in clusters with high, elongated orbits and in field stars of the Galactic thin disk display different dependences on metallicity, age, Galactocentric distance, and the elements of the Galactic orbits, supporting the view that these objects have different natures. In young clusters, not only barium, but also the three other studied s-elements display significantly higher relative abundances than field stars of the same metallicity. The relative abundances of Eu are lower in highmetallicity clusters ([Fe/H] > -0.1) with high, elongated orbits than in field giants, on average, while the [Eu/Fe] ratios in lower-metallicity clusters are the same as those in field stars, on average, although with a large scatter. The metallicity dependence of the [O, Mg/Eu] ratios in clusters with high, elongated orbits and in field stars are substantially different. These and other described properties of the Eu abundances, together with the properties of the abundances of primary a-elements, can be understood in a natural way if clusters with high, elongated orbits with different metallicities formed as a result of interactions of two types of high-velocity clouds with the interstellar medium of the Galactic disk: low-metallicity highvelocity clouds that formed from 'primordial' gas, and high-metallicity clouds with intermediate velocities that formed in 'Galactic fountains.' [ABSTRACT FROM AUTHOR]

Prompt thermal neutron-capture partial γ-ray production cross sections were measured for the first time for the W180(n,γ) reaction using a cold guided-neutron beam at the Budapest Research Reactor. Absolute W181γ-ray cross sections were internally standardized using well-known comparator γ-ray cross sections belonging to the other tungsten isotopes present in the 11.35% enriched W180 sample. Transitions were assigned to levels in W181 based largely upon information available in the literature. The total radiative thermal neutron-capture cross section σ0 was determined from the sum of direct prompt γ-ray cross sections populating the ground state and a modeled contribution accounting for ground-state feeding from the quasicontinuum. In this work, we find σ0=21.67(77) b. A new measurement of the cross section for the 5/2- metastable isomer at 365.6 keV, σ5/2-(181Wm,14.6μs)=19.96(55) b, is also determined. Additionally, primary γ rays, observed for the first time in the W180 (n,γ) reaction, provide the most precise determination for the W181 neutron-separation energy, Sn=6669.02(16) keV. [ABSTRACT FROM AUTHOR]

The neutron capture cross sections of 93 Nb, 103 Rh and 115 In were measured by the time-of-flight method in the energy region from 15 keV to 100 keV. A pulse-height weighting technique was employed to derive the neutron capture cross sections. The neutron capture γ -ray spectra were derived by unfolding the pulse-height spectra with the detector response functions. [ABSTRACT FROM AUTHOR]

The ß decay of the most neutron-rich iron isotopes was investigated, leading to the first determination of the 72Fe half-life and new measurements of the half-lives of 69-71Fe. The experimental results are compared with theoretical predictions and presented in the context of the weak astrophysical rapid neutron capture process. [ABSTRACT FROM AUTHOR]

Gamma-ray transitions following neutron capture in 206Pb have been studied at the cold neutron beam facility of the Budapest Neutron Centre using a metallic sample enriched in 206Pb and a natural lead nitrate powder pellet. The measurements were performed using a coaxial HPGe detector with Compton suppression. The observed $ \gamma$ -rays have been incorporated into a decay scheme for neutron capture in 206Pb . Partial capture cross sections for 206Pb(n, $ \gamma$ ) at thermal energy have been derived relative to the cross section for the 1884keV transition after neutron capture in 14N . From the average crossing sum a total thermal neutron capture cross section of $ 29^{+2}_{-1}$ mb was derived for the 206Pb(n, $ \gamma$ ) reaction. The thermal neutron capture cross section for 206Pb has been compared with contributions due to both direct capture and distant unbound s-wave resonances. From the same measurements a thermal neutron-induced capture cross section of $ (649 \pm 14)$ mb was determined for the 207Pb(n, $ \gamma$ ) reaction. [ABSTRACT FROM AUTHOR]

The new-type scintillator, Ultima Gold Alpha–Beta (UGAB), was studied for its neutron–gamma discrimination capability. The figure-of-merit and peak-to-valley values for the neutron–gamma discrimination spectra of UGAB scintillator when exposed to 241Am–Be neutron source were presented. The results show that this new-type scintillator can efficiently be used in neutron–gamma discrimination experiments. [ABSTRACT FROM PUBLISHER]

Abstract: To date, the most successful nuclear methods to confirm the presence of bulk explosives have been radiative thermal neutron capture (thermal neutron activation) and prompt radiative emission following inelastic fast neutron scattering (fast neutron analysis). This paper proposes an alternative: photoneutron spectroscopy using monoenergetic gamma rays. If monoenergetic gamma rays whose energies exceed the threshold for neutron production are incident on a given isotope, the emitted neutrons have a spectrum consisting of one or more discrete energies and the spectrum can be used as a fingerprint to identify the isotope. A prototype compact gamma-ray generator is proposed as a suitable source and a commercially available 3He ionization chamber is proposed as a suitable spectrometer. Advantages of the method with respect to the previously mentioned ones may include simpler spectra and low inherent natural neutron background. Its drawbacks include a present lack of suitable commercially available photon sources, induced neutron backgrounds and low detection rates. This paper describes the method, including kinematics, sources, detectors and geometries. Simulations using a modified Geant4 Monte Carlo modelling code are described and results are presented to support feasibility. Further experiments are recommended. [Copyright &y& Elsevier]

Abstract: Ice buried beneath a thin layer of soil has been revealed by neutron spectroscopy and explored by the Phoenix Mars Lander. It has also been exposed by recent impacts. This subsurface ice is thought to lose and gain volume in response to orbital variations (Milankovitch cycles). We use a powerful numerical model to follow the growth and retreat of near-surface ice as a result of regolith–atmosphere exchange continuously over millions of years. If a thick layer of almost pure ice has been deposited recently, it has not yet reached equilibrium with the atmospheric water vapor and may still remain as far equatorward as 43°N, where ice has been revealed by recent impacts. A potentially observable consequence is present-day humidity output from the still retreating ice. We also demonstrate that in a sublimation environment, subsurface pore ice can accumulate in two ways. The first mode, widely known, is the progressive filling of pores by ice over a range of depths. The second mode occurs on top of an already impermeable ice layer; subsequent ice accumulates in the form of pasted on horizontal layers such that beneath the ice table, the pores are completely full with ice. Most or all of the pore ice on Mars today may be of the second type. At the Phoenix landing site, where such a layer is also expected to exist above an underlying ice sheet, it may be extremely thin, due to exceptionally small variations in ice stability over time. [Copyright &y& Elsevier]

Abstract: Background: Photoneutrons are produced in radiation therapy with high energy photons. Also, capture gamma rays are the byproduct of neutrons interactions with wall material of radiotherapy rooms. Aim: In the current study an analytical formula was proposed for capture gamma dose calculations in double bend mazes in radiation therapy rooms. Materials and methods: A total of 40 different layouts with double-bend mazes and a 18MeV photon beam of Varian 2100 Clinac were simulated using MCNPX Monte Carlo (MC) code. Neutron capture gamma ray dose equivalent was calculated by the MC method along the maze and at the maze entrance door of all the simulated rooms. Then, all MC resulted data were fitted to an empirical formula for capture gamma dose calculations. Wu–McGinley analytical formula for capture gamma dose equivalent at the maze entrance door in single-bend mazes was also used for comparison purposes. Results: For capture gamma dose equivalents at the maze entrance door, the difference of 2–11% was seen between MC and the derived equation, while the difference of 36–87% was found between MC and the Wu–McGinley methods. Conclusion: Our results showed that the derived formula results were consistent with the MC results for all of 40 different geometries. However, as a new formula, further evaluations are required to validate its use in practical situations. Finally, its application is recommend for capture gamma dose calculations in double-bend mazes to improve shielding calculations. [Copyright &y& Elsevier]

Three Egyptian monazite samples from the beach black sand at Abou Khashba near Rosetta, submitted by the laboratories of the nuclear materials authority of Egypt were analyzed for elemental contents, using Prompt gamma ray neutron activation analysis (PGNAA) as an effective analysis technique especially for rare earth elements. An integrated system for PGNAA, located at hot Lab. Center, has proven useful for the analytical purpose using 252Cf neutron source with neutron flux of 6.16E7 n/cm s, that system has been designed and calibrated for PGNAA. Sensitivity curves using different standard concentration values of artificial liquid standards samples at different concentrations ranging from 1,000 to 5,000 mg/L in case of Sm and Gd, while from 100 to 1,000 mg/L for Eu, have been constructed. The average concentration values for Gd, Sm and Eu in the samples under investigation was at 1.46E4 ± 0.21, 6.683E4 ± 0.14 and 440 ± 0.18 ppm, respectively. A comparative study of the obtained results and the results of ICP-Ms was given. [ABSTRACT FROM AUTHOR]

Exploration and modification of data for k-PGAA (prompt γ-ray activation analysis) values used as standards for k standardization are needed. An integrated system has been installed and calibrated in Hot Laboratories Center for PGAA, using Cf isotopic neutron source with neutron flux of 6.16E8 n/cms. The prompt k-factors of about 12 elements were determined versus the 1951.1 keV γ-ray of the Cl, as well as analyzing crude oil and oil product samples. The concentrations of the elements in crude oil H, B, Mg, Al, Na, Si, P, S, Cl, V and Cd were 1.18E5, 0.084, 5.48E2, 8.45E2 4.88E2, 1.62E2, 3.72E2, 8.2, 144.3, 393 and 209.2 ppm while in oil product samples were 1.32E5, 5.87, 4.56E2, 4.22E2, 7.16E3, 699, 157, 8.74, 492.3, 61 and 198.2 ppm. Validation of the k-PGAA was applied in analyzing standard IAEA reference material (soil-7) which give good agreement with the literature data. The Cf neutron beam in radiation position was characterized by the cadmium-ratio method, and found that the cadmium ratio ( f), was 160. [ABSTRACT FROM AUTHOR]

The response function of a fast neutron capture-gated detector with a simple geometry has been simulated with the aim of studying the mechanism of its formation. The Geant4 package and the DGEOM program developed by the Institute for Nuclear Research especially for studying processes of fast neutron moderation in an organic medium have been used for numerical simulation of the response function. The response functions and the detection efficiencies of an actual detector for neutron energies of 1.2, 2.4, 5.0, and 14.6 MeV have been reconstructed and analyzed. The behavior of the response function has been comprehensively analyzed in the neutron energy range of 1-14 MeV. It is shown that our simulation adequately represents the experimental data and that the response function of the detector has a double-peak structure deteriorating its energy resolution. Taking into account the interaction with carbon for neutrons with energies of <15 MeV affects the response function only slightly. The consistency of the physical model involved in the DGEOM program and the adequacy of the simulation results obtained using this program are demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: The low energy region of magnon excitations of an off-stoichiometric Ni49.1Mn29.4Ga21.5 single crystal has been investigated by neutron spectroscopy. The lowest magnetic exchange stiffness constant D of 97±2meVÅ2 has been found in the cubic austenite phase. In the two martensitic phases the exchange stiffness constants are significantly larger with values of 149±4meVÅ2 in the tetragonal phase and 198±7meVÅ2 in the low temperature martensite. The large value of D in the low temperature phase compared to the other phases cannot be explained solely by renormalization effects due to magnon–magnon interaction and is attributed to a stronger magnetic coupling. In both the martensitic phases a gap of magnon excitation at the Γ-point of about 0.2meV was observed. [ABSTRACT FROM AUTHOR]

Artificial crystal diamond neutron detectors are under test at JET tokamak since 2003 and they have demonstrated to be reliable and stable as well as to withstand the harsh working condition available in a large tokamak. Up to now they were used to measure the total and time dependent neutron emission while neutron spectroscopy was never attempted. On the other hand neutron spectrometry con yields important information on the burning plasma and it is requested for future experiments that will use DT plasmas so producing 14 MeV neutrons. Neutron spectrometry can only be attempted by using single crystal diamond (SCD) which, as it has been demonstrated, can show an energy resolution (FWHM) as low as 0.5%. [ABSTRACT FROM AUTHOR]

Abstract: Forest soils are pivotal to understanding global carbon (C) cycling and evaluating policies for mitigating global change. However, they are very difficult to monitor because of the heterogeneity of soil characteristics, the difficulty of representative sampling, and the slow time scale of response to environmental change. Here we demonstrate that use of gamma-ray spectroscopy facilitates in situ non-destructive analysis of C and other elements in forest soils. In this approach the element-specific gamma-rays are induced by fast and thermal neutrons interacting with the nuclei of the elements present in the soil. Background gamma-rays emanating from naturally occurring radionuclides in the forest are recorded as well. We applied this approach in a mature northern hardwood forest on glacial till soils at the Bartlett Experimental Forest in New Hampshire, USA. The inelastic neutron scattering (INS) system yielded strong signals in gamma-ray counts/h, from C and other elements present in the soil matrix that included silicon, oxygen, hydrogen, iron, aluminum, manganese and potassium. The INS sensitivity for carbon was 20.656 countsh−1 kg−1 Cm−2 based on current net C gamma-ray counts and the data for the O horizon and mineral soil to a depth of 30cm obtained from a nearby quantitative soil pit (7.35kgCm−2). We estimate the minimum detectable change to be ∼0.34kgCm−2, which is ∼5% of the current soil C content, and the minimum detectable limit to be ∼0.23kgCm−2. Eight % reproducibility from 11 measurements was limited, in part, by the large variability in the system counting geometry due to the uneven forest microtopography. The INS approach has the potential to revolutionize belowground monitoring of C and other elements, because the possibility of detecting a 5% change in forest soils has not been possible with destructive sampling methods. [Copyright &y& Elsevier]

High-resolution spectra obtained from the Subaru Telescope High Dispersion Spectrograph have been used to update the stellar atmospheric parameters and metallicity of the star HD 209621. We have derived a metallicity of for this star, and have found a large enhancement of carbon and of heavy elements, with respect to iron. Updates on the elemental abundances of four s-process elements (Y, Ce, Pr, Nd) along with the first estimates of abundances for a number of other heavy elements (Sr, Zr, Ba, La, Sm, Eu, Er, Pb) are reported. The stellar atmospheric parameters, the effective temperature, Teff, and the surface gravity, log g (4500 K, 2.0), are determined from local thermodynamic equilibrium analysis using model atmospheres. Estimated [Ba/Eu]=+0.35, places the star in the group of CEMP-(r+s) stars; however, the s-elements abundance pattern seen in HD 209621 is characteristic of CH stars; notably, the second-peak s-process elements are more enhanced than the first-peak s-process elements. HD 209621 is also found to show a large enhancement of the third-peak s-process element lead (Pb) with . The relative contributions of the two neutron-capture processes, r and s, to the observed abundances are examined using a parametric model-based analysis, which hints that the neutron-capture elements in HD 209621 primarily originate in s-process. [ABSTRACT FROM AUTHOR]

The search for water on the surface of the anhydrous Moon had remained an unfulfilled quest for 40 years. However, the Moon Mineralogy Mapper (M³) on Chandrayaan-1 has recently detected absorption features near 2.8 to 3.0 micrometers on the surface of the Moon. For silicate bodies, such features are typically attributed to hydroxyl- and/or water-bearing materials. On the Moon, the feature is seen as a widely distributed absorption that appears strongest at cooler high latitudes and at several fresh feldspathic craters. The general lack of correlation of this feature in sunlit M³ data with neutron spectrometer hydrogen abundance data suggests that the formation and retention of hydroxyl and water are ongoing surficial processes. Hydroxyl/water production processes may feed polar cold traps and make the lunar regolith a candidate source of volatiles for human exploration. [ABSTRACT FROM AUTHOR]

Abstract: A large area plastic scintillator detector array () has been set up for fast neutron spectroscopy at the BARC-TIFR Pelletron laboratory, Mumbai. The energy, time and position response has been measured for electrons using radioactive sources and for monoenergetic neutrons using the 7Li reaction at proton energies between 6.3 and 19MeV. A Monte Carlo simulation of the energy dependent efficiency of the array for neutron detection is in agreement with the 7Li measurements. The array has been used to measure the neutron spectrum, in the energy range of 4–12MeV, in the reaction at . This is in reasonable agreement with a statistical model calculation. [Copyright &y& Elsevier]

Abstract: A novel algorithm for the digital discrimination of neutrons and gamma-rays in a mixed radiation field is presented. Most of the pulse shape discrimination methods in scintillation detection systems use time-domain features of the signal (e.g. charge comparison method or constant-time discrimination). However, there are no frequency-domain discrimination methods up to date in the literature. Our method employs the wavelet transform to extract frequency-domain features for discrimination. Compared to the pulse gradient analysis (PGA) algorithm, it provides an improvement in reducing the overlap area between neutron and gamma events and also in increasing the Figure of Merit (FoM). Another advantage of this method consists in the removal of the dependency of the discrimination method on timing features. Since the light output in the scintillation process is very noisy, this kind of dependency may degrade the performance of the algorithm. [Copyright &y& Elsevier]

The third centuryad was a complex period of crisis in the Roman world. In this paper, official and unofficial antoniniani, and double sestercii and sestercii, were analysed by fast neutron activation analysis (FNAA) to determine the alloys used by the craftsmen for producing forgeries. Moreover, at Châteaubleau, archaeologists discovered antoniniani and bronze forgeries from Postumus. Similar materials have been found in other hoards. They are believed to have been produced by a workshop called ‘atelier II’ by numismatists. The question was whether it is possible to differentiate the Châteaubleau production from the atelier II production. [ABSTRACT FROM AUTHOR]

A spectroscopy system measuring inelastic neutron scattering and thermal neutron capture induced gamma-rays is being developed for in-situ soil analysis. Because a pulsed fast D-T neutron source is utilized, fast neutron induced inelastic neutron scattering reactions are separated in time from thermal neutron capture events. Models utilizing the MCNPX code have been developed to study the time and energy variations of the neutrons in the soil matrix. [ABSTRACT FROM AUTHOR]

We report on an adaptive binning approach designed for data visualization within scientific disciplines where counting statistics are expected to follow Poisson distributions. We envisage a wide range of applications stemming from astrophysics to the condensed matter sciences. Our main focus of interest concerns, however, neutron spectroscopy data from single-crystal samples where signals span a four-dimensional space defined by three spatial coordinates plus time. This makes widely used equal-width binning schemes inadequate since physically relevant information is often concentrated within rather small regions of such a space. Our aim is thus to generate optimally binned data sets from one-dimensional to three-dimensional volumes to provide the experimentalist with enhanced ability to carry out searches within a four-dimensional space. Several binning algorithms are then scrutinized against experimental as well as simulated data. [ABSTRACT FROM AUTHOR]

A new logging-while-drilling (LWD) tool that combines traditional measurements of gamma ray, propagation resistivity, gamma-gamma density, and thermal-neutron porosity with measurements unique to the LWD arena, including neutron capture spectroscopy and capture cross section, opens up new opportunities for formation evaluation on LWD. The compact design of the new-generation LWD tool greatly increases the likelihood that measurements will be made before the onset of significant invasion. The colocation of resistivity- and neutron-based sensors also means that key measurements are being made at the same depth at the same time and on a similar volume of the formation. These features ensure that all measurements are essentially seeing the same amount of invasion, thus removing a major complication in conventional LWD interpretation. [ABSTRACT FROM AUTHOR]

Monte Carlo calculations were carried out to study the dependence of γ-ray yield on the bulk density and moisture content of a sample in a thermal-neutron capture-based prompt gamma neutron activation analysis (PGNAA) setup. The results of the study showed a strong dependence of the γ-ray yield upon the sample bulk density. An order of magnitude increase in yield of 1.94 and 6.42 MeV prompt γ-rays from calcium in a Portland cement sample was observed for a corresponding order of magnitude increase in the sample bulk density. On the contrary the γ-ray yield has a weak dependence on sample moisture content and an increase of only 20% in yield of 1.94 and 6.42 MeV prompt γ-rays from calcium in the Portland cement sample was observed for an order of magnitude increase in the moisture content of the Portland cement sample. A similar effect of moisture content has been observed on the yield of 1.167 MeV prompt γ-rays from chlorine contaminants in Portland cement samples. For an order of magnitude increase in the moisture content of the sample, a 7 to 12% increase in the yield of the 1.167 MeV chlorine γ-ray was observed for the Portland cement samples containing 1 to 5 wt.% chlorine contaminants. This study has shown that effects of sample moisture content on prompt γ-ray yield from constituents of a Portland cement sample are insignificant in a thermal-neutrons capture-based PGNAA setup. [ABSTRACT FROM AUTHOR]

In this paper we present first results from a 8Li electromagnetic neutron-breakup experiment. Specific reactions studied were Pb( 8Li, 7Li+ n) Pb and C( 8Li, 7Li+ n) C at 41MeV/nucleon beam energy. This is an effort to compare the results of a Coulomb dissociation experiment with the well determined ( n,γ) reaction cross sections at astrophysical energies. The angular dependence of the cross section above 7 degree, which is the grazing angle of 8Li- Pb system, is similar in shape for lead and carbon and approximately proportional to A 2/3 in magnitude indicating that the nuclear dissociation is the main component in this region. At very forward angles the angular distributions differ significantly and the electromagnetic dissociation dominates for the lead, although the nuclear contribution is not negligible. [ABSTRACT FROM AUTHOR]

The results of the development (“renaissance”) of giant-resonance physics are briefly discussed from the point of view of their application to creating a photonuclear database. It is indicated that part of the recommendations from corresponding libraries of data are not at the level of the present-day status of giant-resonance physics. A Lorentzian parametrization of the most reliable experimental data on isovector M1 resonances is constructed for seven spherical nuclei, and it is shown that the widths of M1 resonances are severalfold, sometimes an order of magnitude, smaller than the value of Γ0 = 4 MeV, which was recommended for all nuclei. The need for microscopically taking into account configurations more complex than those that are included within the standard random-phase approximation or within the quasiparticle random-phase approximation is emphasized. To be more precise, it is necessary to take into account coupling to phonons, since this changes the temperature dependence of the resonance width in relation to that which was used earlier and since, without this, one cannot explain the properties of pygmy dipole resonances in the region of the nucleon binding energy. Our calculations of the average energies of the pygmy dipole resonances in the Ca and Sn isotopes within the microscopic extended theory of finite Fermi systems reveal that the inclusion of coupling to phonons reduces these energies considerably toward the improvement of agreement with experimental data. The idea of creating a library of photonuclear data for unstable nuclei, including fission fragments, on the basis of the extended theory of finite Fermi systems is discussed in connection with the fact that information necessary for fitting the parameters of phenomenological theories is absent or insufficient for such nuclei. [ABSTRACT FROM AUTHOR]

Proton acceleration inside solid LiF and CH–LiF targets irradiated by a 450-fs, 20-J, 1053-nm laser at an intensity of 3×1018 W/cm2 has been studied via neutron spectroscopy. Neutron spectra produced through the 7Li(p,n)7Be reaction that occurs between accelerated protons, at the front surface, and background 7Li ions inside the target. From measured and calculated spectra, by three–dimensional Monte Carlo code, the maximum energy, total number, and slope temperature of the accelerated protons are investigated. The study indicates that protons originate at the front surface and are accelerated to a maximum energy that is reasonably consistent with the calculated one due to the ponderomotive force. [ABSTRACT FROM AUTHOR]

The abundance of elements between Fe and the actinides have essentially all been produced by neutron reactions, either by the slow neutron capture process during helium burning in red giant stars ( s process) or by explosive nucleosynthesis, e.g. in supernovae ( r and p process). Laboratory studies have so far concentrated on the s process, which operates in or near the valley of β-stability. Under these conditions laboratory results are of direct impact for the interpretation of the observed abundance patterns and their role as crucial tests for stellar evolution models. The high flux at spallation neutron sources allows one to investigate numerous difficult and hitherto inaccessible cases, including the cross sections of important radioactive nuclei. [ABSTRACT FROM AUTHOR]

The object of this work was to determinate the radioactive levels in soil samples and in the agricultural products from the Central-south region of Cuba. Approximately, 200 analysis were done The strontium 90 was determinated by radiochemical separation and the determination of gamma emitters contents in the samples was carried out by spectrometric analysis, using a semiconductor detector (Ge-Li), a scintillation detector Nal (TI) and HPGe detector. The results obtained in the components studied: soils and agricultural products, show that the concentrations of natural radionuclides are similar to those reported for normal regions. In the case of artificial radionuclides, their concentrations are similar to those reported for regions which have been affected only by the global radioactive precipitations. [ABSTRACT FROM AUTHOR]

To obtain the highest possible resolution in a measurement has always been one of the major challenges for experimental physicists because increased resolution generally results in progress. At the Institut Laue-Langevin, gamma rays emitted after neutron capture can be recorded with parts-per-million resolution. This is achieved by diffracting the gamma rays on highly perfect Si or Ge crystals. Precise measurement of the Bragg angles and the crystal lattice spacings permits the determination of wavelengths or energies. This outstanding resolving power allows the measurement of extremely small Doppler effects caused by the emission of primary gamma rays. These so-called gamma-ray-induced Doppler broadening measurements have given rise to applications in both nuclear and condensed matter physics. [ABSTRACT FROM AUTHOR]