The joint evaluated fission and fusion nuclear data library 3.3 is described. New evaluations for... more The joint evaluated fission and fusion nuclear data library 3.3 is described. New evaluations for neutron-induced interactions with the major actinides $$^{235}\hbox {U}$$ 235 U , $$^{238}\hbox {U}$$ 238 U and $$^{239}\hbox {Pu}$$ 239 Pu , on $$^{241}\hbox {Am}$$ 241 Am and $$^{23}\hbox {Na}$$ 23 Na , $$^{59}\hbox {Ni}$$ 59 Ni , Cr, Cu, Zr, Cd, Hf, W, Au, Pb and Bi are presented. It includes new fission yields, prompt fission neutron spectra and average number of neutrons per fission. In addition, new data for radioactive decay, thermal neutron scattering, gamma-ray emission, neutron activation, delayed neutrons and displacement damage are presented. JEFF-3.3 was complemented by files from the TENDL project. The libraries for photon, proton, deuteron, triton, helion and alpha-particle induced reactions are from TENDL-2017. The demands for uncertainty quantification in modeling led to many new covariance data for the evaluations. A comparison between results from model calculations u...
Total Cross Section of Sulphur at Slow Neutron Energies
Zeitschrift für Naturforschung A
The total cross section of elemental Sulphur was measured at neutron energies between 1.6 x 10-3 ... more The total cross section of elemental Sulphur was measured at neutron energies between 1.6 x 10-3 eV and 100 eV, using a pulsed neutron source and time-of-flight techniques. The data in the epithermal neutron region were used to extract the value of the bound nucleus scattering length, taking into account the neutron-electron interaction. A similar transmission experiment was also performed on elemental Bismuth.
Simple expressions are given which accurately describe the total cross section of solids at cold ... more Simple expressions are given which accurately describe the total cross section of solids at cold and epithermal neutron energies. They are intended to provide a consistent procedure for the evaluation of solid state effects, which must be substracted from the experimental data when information is wanted on intrinsic nuclear properties. The formulae presented here are the asymptotic forms to which the full expressions reduce in those energy limits. A Debye model is adopted to describe the frequency spectrum of the solid. The present results are compared with some commonly used expressions as well as with the exact formalism. The effect of temperature is discussed and numerical calculations are presented for some cases.
In this paper we examine the standard procedure employed to obtain peak intensities from the expe... more In this paper we examine the standard procedure employed to obtain peak intensities from the experimental data of deep inelastic neutron scattering experiments. Our analysis is focussed on the hydrogen, deuterium and oxygen peaks observed in experiments on heavy water and the D 2 O=H 2 O equimolar mixture. As a result of our analysis we conclude that the usual procedure (based on a convolution formalism) introduces errors in the determination of the peak areas, and that the analysis must be based on an exact formalism, that was previously published. The present paper brings consequences on the quantitative results of recent publications.
Motivated by the practical requirements of reactor-physics calculations as well as the necessity ... more Motivated by the practical requirements of reactor-physics calculations as well as the necessity of applying inelasticity corrections to the observed spectrum in neutron-diffraction work on molecular gases and liquids, I have developed a synthetic scattering function T(Q, co;Eo) which allows a fast and reliable evaluation of cross sections. Unlike the dynamic structure factor (or scattering function) S(g,ro) in thermal neutron-scattering theory, T(Q, co;Eo) does not contain a detailed description of the atomic motions in the molecular units nor correlation between pairs, but rather it is intended to reproduce satisfactorily some integral properties of S(Q,co) (the self-component). However, the main characteristics of the molecular dynamics are retained through the introduction of an effective mass, and temperature and vibrational factors which depend on the incident neutron energy Eo. This is achieved by the use of the Krieger-Nelkin procedure for orientational averages and by the introduction of "switching functions" P (Eo) which define the variation with Eo of the above effective quantities. A very simple form is thus obtained for T(Q, co;Eo) which yields analytic expressions for the scattering kernel and the total cross section. To gauge the merits and limitations of this prescription I compared its predictions with experiments and other theories in the foIlowing cases involving hydrogen-containing molecules: (i) the total cross section of H20 and C6H6, ' (ii) the scattering cross sections (angular distributions) of H20 and D2O at several energies; and (iii) the average of the cosine of the scattering angle in H20. It is concluded from the comparisons that the model works in a very satisfactory way. It is anticipated that the present prescription could be a useful tool for the evaluation of departures from elasticity in time-of-flight experiments, where a wide range of neutron wavelengths may contribute at each channel in the observed diffraction spectrum.
Many neutron-physics calculations do not require a very detailed description of the atomic motion... more Many neutron-physics calculations do not require a very detailed description of the atomic motions in a molecular system nor correlations between pairs (coherence effects). A synthetic scattering function
Neutronic methods for determination of very low concentrations of hydrogen in metals(Metodos neutronicos para la determinacion de muy bajas concentraciones de hidrogeno en metales)
Multiple scattering effects in deep inelastic neutron scattering experiments
ABSTRACT We present a correction procedure to account for multiple scattering effects in Deep Ine... more ABSTRACT We present a correction procedure to account for multiple scattering effects in Deep Inelastic Neutron Scattering experiments in molecular systems, based on a Monte Carlo simulation in which the energy-transfers are described with a synthetic model. Experimental results in polyethylene samples of different thicknesses performed at the Bariloche LINAC are presented along with numerical simulations that show a good agreement between experiment and calculations. It is shown that multiple scattering effects may cause an important non-symmetric effect on the observed peaks.
Total Neutron Cross-Section of Teflon Between 0.00038-EV and 590-EV
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 1995
The neutron total cross section of Teflon has been measured for energies between 3.8 × 10−4 eV an... more The neutron total cross section of Teflon has been measured for energies between 3.8 × 10−4 eV and 5.9 × 102 eV by the transmission method with pulsed neutron time-of-flight techniques. In order to cover that wide energy range, two independent measurements were performed on samples with different thicknesses and employing as neutron moderator a conventional polyethylene slab for the
Development of Cold Neutron Scattering Kernels for Advanced Moderators
Abstract The development of scattering kernels for a number of molecular systems was performed, i... more Abstract The development of scattering kernels for a number of molecular systems was performed, including a set of hydrogeneous methylated aromatics such as toluene, mesitylene, and mixtures of those. In order to partially validate those new libraries, we ...
New measurement of the total neutron cross section of DâO at 20°C between 0.0005 and 10 eV
We analyze a recent work of Mayers and Abdul-Redah,[J.Phys.: Condens. Matter {\bf 16}, 4811 (2004... more We analyze a recent work of Mayers and Abdul-Redah,[J.Phys.: Condens. Matter {\bf 16}, 4811 (2004)] in which the autors report the existence of anomalous neutron cross sections in several systems. In the present work we show that the Deep Inelastic Neutron Scattering (DINS) results presented by the authors are affected by an inaccurate formalism employed for obtaining nuclear momentum distributions, and therefore definitive conclusions cannot be drawn on the subject of anomalous cross sections. We also show the reasons why the exact formalism for obtaining momentum distributions that we recently published must be employed for analysing the experimental data instead of the approximations performed in the mentioned work. We also point out serious inconsistencies between different results reported in the mentioned work, as well as incompatibilities with previous results published by the authors. These inconsistencies, as well as experimental evidence against the existence of anomalous ...
Search for Anomalous Effects in H2O/D2O Mixtures by Neutron Total Cross Section Measurements
Physical Review Letters, 2003
We investigate anomalies ascribed to quantum entanglement phenomena recently reported in deep ine... more We investigate anomalies ascribed to quantum entanglement phenomena recently reported in deep inelastc neutron scattering (DINS) measurements by an independent neutron technique on H(2)O/D(2)O mixtures. We performed transmission experiments to study several liquid H(2)O/D(2)O mixtures at room temperature in the epithermal energy range. We obtain the total cross sections of the mixtures, which are in agreement with the expected results according to the tabulated values within a 0.3% relative error. We observe no anomalies and stress the limitations of the validity of the data-processing procedures employed in the DINS experiments where the anomalies were reported.
Blostein, Dawidowski, and Granada Reply
Physical Review Letters, 2004
ABSTRACT A Reply to the Comment by E. B. Karlsson and J. Myers.
Neutron cross sections of cold moderators: An approximate algorithm for the description of synthetic kernels for molecular solids
Physica B: Condensed Matter, 2006
An approximate synthetic scattering function aimed at the description of the interaction of therm... more An approximate synthetic scattering function aimed at the description of the interaction of thermal neutrons with hydrogenous molecular solids has been developed. At low incident neutron energies, lattice modes and molecular rotations are accounted for, through an ...
In this work we present neutron total cross-section measurements on H 2 O/D 2 O liquid mixtures a... more In this work we present neutron total cross-section measurements on H 2 O/D 2 O liquid mixtures at room temperature in the epithermal energy range employing the transmission technique at the Bariloche electron linear accelerator (LINAC) (Argentina). The analysis of the asymptotic behavior shows that the Hydrogen, Deuterium, and Oxygen mean kinetic energies obtained for the different molecular species (H 2 O, D 2 O and HDO) are in excellent agreement with the reference values presented in the literature. Transmission being a technique extremely simple, the results are free of several corrections and characterizations of the experimental setup which are necessary to apply in more detailed techniques. The results presented in this work show the utility of transmission experiments, not only for obtaining values of neutron cross sections, but also to perform dynamic analysis useful to verify different models proposed to describe the interaction between neutrons and different systems of interest.
On the analysis of deep inelastic neutron scattering experiments for light nuclei
Physica B: Condensed Matter, 2001
... 2, 1 with the parameters taken from Ref. [11] and a modified width to account for the Doppler... more ... 2, 1 with the parameters taken from Ref. [11] and a modified width to account for the Doppler broadening; (iii) a Lorentzian function in the variable y, fitted from resolution function (ii). Fig. 3 shows these resolution functions for hydrogen and deuterium. ...
The total cross section of natural lead was measured for neutron encrgics between 1 cV and 9(N) e... more The total cross section of natural lead was measured for neutron encrgics between 1 cV and 9(N) eV, in a time-of-flight transmission experiment at the KURRI Electron Linear Accelerator pulsed neutron source. The mcasurcd data were used to determine the neutron electrical polarizability, after a careful analysis of the different contributions to the neutron-atom scattering length. The result obtained, (Y = (2.4 5 1.5) X 10-' fm', is consistent with the most recent and accurate values, while at the same time it emphasizes the need of better statistics and the use of isotopically enriched samples to improve its precision.
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Papers by J. Granada