A generalized mean-squared displacement from inelastic fixed window scans of incoherent neutron scattering as a model-free indicator of anomalous diffusion confinement

International Nuclear Information System (INIS)

Roosen-Runge, F.; Seydel, T.

2015-01-01

Elastic fixed window scans of incoherent neutron scattering are an established and frequently employed method to study dynamical changes, usually over a broad temperature range or during a process such as a conformational change in the sample. In particular, the apparent mean-squared displacement can be extracted via a model-free analysis based on a solid physical interpretation as an effective amplitude of molecular motions. Here, we provide a new account of elastic and inelastic fixed window scans, defining a generalized mean-squared displacement for all fixed energy transfers. We show that this generalized mean-squared displacement in principle contains all information on the real mean-square displacement accessible in the instrumental time window. The derived formula provides a clear understanding of the effects of instrumental resolution on the apparent mean-squared displacement. Finally, we show that the generalized mean-square displacement can be used as a model-free indicator on confinement effects within the instrumental time window. (authors)

Quasi-elastic neutron scattering study of a re-entrant side-chain liquid-crystal polyacrylate

Science.gov (United States)

Benguigui, L.; Noirez, L.; Kahn, R.; Keller, P.; Lambert, M.; Cohen de Lara, E.

1991-04-01

We present a first investigation of the dynamics of a side chain liquid crystal polyacrylate in the isotropic (I), nematic (N), smectic A (SA), and re-entrant nematic (NRe) phases by means of quasi-elastic neutron scattering. The motion or/and the mobility of the mesogen protons decreases as soon as the temperature decreases after the isotropic-nematic transition. The I-N and SA-NRe transitions corrspond to a jump in the curve of the Elastic Incoherent Structure Factor (ratio: elastic scattering/ total scattering) versus temperature, on the other hand the transition N-SA occurs without any change of slope. We conclude that the local order is very similar in the nematic and the smectic A phases. Nous présentons une première étude dynamique par diffusion quasi-élastique des neutrons, d'un échantillon de polyacrylate mésomorphe en peigne dans chacune des phases : isotrope, nématique, smectique et nématique rentrante. On montre que le mouvement et/ou la mobilité des protons du mésogène se restreint à mesure que la température diminue après la transition isotrope-nématique. Contrairement à la transition N-SA, les transitions I-N et SA-NRe correspondent à une discontinuité dans la courbe du Facteur de Structure Incohérent Elastique (rapport : intensité élastique/intensité totale) en fonction de la température ; l'ordre local semble donc très proche pour les phases nématique et smectique.

Bound coherent and incoherent thermal neutron scattering cross sections of the elements

International Nuclear Information System (INIS)

Sears, V.F.

1982-12-01

An up-to-date table of bound coherent and incoherent thermal neutron scattering cross sections of the elements is presented. Values from two different data sources are calculated and compared. These sources are: (1) the free-atom cross sections listed in the Σbarn bookΣ and (2) the Julich scattering length tables. We also call attention to, and clarify, the confusion that exists in the literature concerning the sign of the imaginary part of the complex scattering length

Quasi-elastic measurements using neutron spin flippers

International Nuclear Information System (INIS)

Bleuel, M.; Fitzsimmons, M.R.; Lal, J.

2008-01-01

A method for low-resolution quasi-elastic measurements using commonly available components on a polarized neutron beam reflectometer is demonstrated. By amplitude modulation of the current in a neutron spin flipper placed between the neutron beam polarizer and polarization analyzer, the intensity of the neutron beam illuminating a sample is similarly modulated (or chopped). We show that the intensity contrast between subsequent chopped pulses is dramatically reduced by a sample that changes neutron velocity

Incoherent quasielastic neutron scattering from plastic crystals

International Nuclear Information System (INIS)

Bee, M.; Amoureux, J.P.

1980-01-01

The aim of this paper is to present some applications of a method indicated by Sears in order to correct for multiple scattering. The calculations were performed in the particular case of slow neutron incoherent quasielastic scattering from organic plastic crystals. First, an exact calculation (up to second scattering) is compared with the results of a Monte Carlo simulation technique. Then, an approximation is developed on the basis of a rotational jump model which allows a further analytical treatment. The multiple scattering is expressed in terms of generalized structure factors (which can be regarded as self convolutions of first order structure factors taking into account the instrumental geometry) and lorentzian functions the widths of which are linear combinations of the jump rates. Three examples are given. Two of them correspond to powder samples while in the third we are concerned with the case of a single crystalline slab. In every case, this approximation is shown to be a good approach to the multiple scattering evaluation, its main advantage being the possibility of applying it without any preliminary knowledge of the correlation times for rotational jumps. (author)

Neutron scattering studies of the dynamics of biological systems as a function of hydration, temperature and pressure

International Nuclear Information System (INIS)

Trapp, Marcus

2010-01-01

Incoherent elastic and quasi-elastic neutron scattering were used to measure membrane and protein dynamics in the nano- to picosecond time and Angstrom length scale. The hydration dependent dynamics of DMPC model membranes was studied using elastic and quasi-elastic neutron scattering. The elastic experiments showed a clear shift of the temperature of the main phase transition to higher temperatures with decreasing hydration level. The performed quasi-elastic measurements demonstrated nicely the influence, hydration has on the diffusive motions of the head lipid groups. Different models are necessary to fit the Q-dependence of the elastic incoherent structure factor and show therefore the reduced mobility as a result of reduced water content. In addition to temperature, pressure as a second thermodynamic variable was used to explore dynamics of DMPC membranes. The ordering introduced by applying pressure has similar effect to decreased hydration, therefore both approaches are complementary. Covering three orders of magnitude in observation time, the dynamics of native AChE and its complexed counterpart in presence of Huperzin A was investigated in the range from 1 ns to 100 ps. The mean square displacements obtained from the elastic data allowed the determination of activation energies and gave evidence that a hierarchy of motions contributes to the enzymatic activity. Diffusion constants and residence times were extracted from the quasi-elastic broadening. (author) [fr

Studies of molecular dynamics with neutron scattering techniques. Part of a coordinated programme on neutron scattering techniques

International Nuclear Information System (INIS)

Vinhas, L.A.

1980-05-01

Molecular dynamics was studied in samples of tert-butanol, cyclohexanol and methanol, using neutron inelastic and quasi-elastic techniques. The frequency spectra of cyclohexanol in crystalline phase were interpreted by assigning individual energy peaks to hindered rotation of molecules, lattice vibration, hydrogen bond stretching and ring bending modes. Neutron quasi-elastic scattering measurements permitted the testing of models for molecular diffusion as a function of temperature. The interpretation of neutron incoherent inelastic scattering on methanol indicated the different modes of molecular dynamics in this material; individual inelastic peaks in the spectra could be assigned to vibrations of crystalline lattice, stretching of hydrogen bond and vibrational and torsional modes of CH 3 OH molecule. The results of the experimental work on tertbutanol indicate two distinct modes of motion in this material: individual molecular librations are superposed to a cooperative rotation diffusion which occurs both in solid and in liquid state

Microscopic dynamics of the hydrogen bonded systems studied by quasi-elastic slow neutron scattering

International Nuclear Information System (INIS)

Padureanu, I.; Aranghel, D.; Radulescu, A.; Ion, M.; Lechner, R. E.; Desmedt, A.; Pieper, J.

2002-01-01

provide a satisfactory description of supercooled liquid dynamics. In order to contribute to an answer, we performed a new experiment of incoherent slow neutron scattering. Part of the obtained results is presented in a previously paper. Neutron scattering experiments were done at the time of flight spectrometer NEAT of the Berlin Neutron Scattering Center(BENSC). In this study we have used cold neutrons with the wavelength of λ = 5.1 A, which corresponds to an incident energy E o = 3.145 meV and a resolution ΔE = 98 μeV (full width at half-maximum, FWHM, of the elastic line of the vanadium sample). The scattering spectra were taken with 140 detectors in a large angular range 15.41 angle -1 for the elastic wave and the energy transfer hω s (θ,ω). The final data are obtained at 27 scattering angles as a function of the energy transfer hω for 8 temperatures 50 K, 100 K, 150 K, 188 K, 240 K, 290 K, 320 K and 400 K. The data have been also analyzed in terms of the generalized frequency distribution g (ω), the angular distribution dσ/dΩ of the quasi-elastically scattered neutrons and the observed line width ΔE = f (Q 0 2 , T). An obvious feature attribute to as boson peak is present at all temperatures from 50 K to 290 K in the dynamic scattering function Ss (θ,ω) and the generalized frequency distribution g (ω)/ω 2 of glycerol. The temperature dependence of the peak position shows an anomalous behavior near T g . This effect proves a soft dynamics additionally to the acoustic modes. At the same time the temperature dependence of the FWHM of the quasielastic line leads to a possible two step process approach in glycerol. (authors)

Thermal Neutron Capture and Thermal Neutron Burn-up of K isomeric state of 177mLu: a way to the Neutron Super-Elastic Scattering cross section

International Nuclear Information System (INIS)

Roig, O.; Belier, G.; Meot, V.; Daugas, J.-M.; Romain, P.; Aupiais, J.; Jutier, Ch.; Le Petit, G.; Letourneau, A.; Marie, F.; Veyssiere, Ch.

2006-01-01

Thermal neutron radiative capture and burn-up measurements of the K isomeric state in 177Lu form part of an original method to indirectly obtain the neutron super-elastic scattering cross section at thermal energy. Neutron super-elastic scattering, also called neutron inelastic acceleration, occurs during the neutron collisions with an excited nuclear level. In this reaction, the nucleus could partly transfer its excitation energy to the scattered neutron

From coherent to incoherent mismatched interfaces: A generalized continuum formulation of surface stresses

Science.gov (United States)

Dingreville, Rémi; Hallil, Abdelmalek; Berbenni, Stéphane

2014-12-01

The equilibrium of coherent and incoherent mismatched interfaces is reformulated in the context of continuum mechanics based on the Gibbs dividing surface concept. Two surface stresses are introduced: a coherent surface stress and an incoherent surface stress, as well as a transverse excess strain. The coherent surface stress and the transverse excess strain represent the thermodynamic driving forces of stretching the interface while the incoherent surface stress represents the driving force of stretching one crystal while holding the other fixed and thereby altering the structure of the interface. These three quantities fully characterize the elastic behavior of coherent and incoherent interfaces as a function of the in-plane strain, the transverse stress and the mismatch strain. The isotropic case is developed in detail and particular attention is paid to the case of interfacial thermo-elasticity. This exercise provides an insight on the physical significance of the interfacial elastic constants introduced in the formulation and illustrates the obvious coupling between the interface structure and its associated thermodynamics quantities. Finally, an example based on atomistic simulations of Cu/Cu2O interfaces is given to demonstrate the relevance of the generalized interfacial formulation and to emphasize the dependence of the interfacial thermodynamic quantities on the incoherency strain with an actual material system.

Determination of the effective transverse coherence of the neutron wave packet as employed in reflectivity investigations of condensed-matter structures. II. Analysis of elastic scattering using energy-gated wave packets with an application to neutron reflection from ruled gratings

Science.gov (United States)

Berk, N. F.

2014-03-01

We present a general approach to analyzing elastic scattering for those situations where the incident beam is prepared as an incoherent ensemble of wave packets of a given arbitrary shape. Although wave packets, in general, are not stationary solutions of the Schrödinger equation, the analysis of elastic scattering data treats the scattering as a stationary-state problem. We thus must gate the wave packet, coherently distorting its shape in a manner consistent with the elastic condition. The resulting gated scattering amplitudes (e.g., reflection coefficients) thus are weighted coherent sums of the constituent plane-wave scattering amplitudes, with the weights determined by the shape of the incident wave packet as "filtered" by energy gating. We develop the gating formalism in general and apply it to the problem of neutron scattering from ruled gratings described by Majkrzak et al. in a companion paper. The required exact solution of the associated problem of plane-wave reflection from gratings also is derived.

7Li neutron-induced elastic scattering cross section measurement using a slowing-down spectrometer

Directory of Open Access Journals (Sweden)

Heusch M.

2010-10-01

Full Text Available A new integral measurement of the 7Li neutron induced elastic scattering cross section was determined in a wide neutron energy range. The measurement was performed on the LPSC-PEREN experimental facility using a heterogeneous graphite-LiF slowing-down time spectrometer coupled with an intense pulsed neutron generator (GENEPI-2. This method allows the measurement of the integral elastic scattering cross section in a slowing-down neutron spectrum. A Bayesian approach coupled to Monte Carlo calculations was applied to extract naturalC, 19F and 7Li elastic scattering cross sections.

The effect of, within the sphere confined, particle diffusion on the line shape of incoherent cold neutron scattering spectra

International Nuclear Information System (INIS)

Cvikl, B.; Dahlborg, U.; Calvo-Dahlborg, M.

1999-01-01

Based upon the model of particles diffusion within the sphere of partially absorbing boundaries, the possibilities of the detection, by the incoherent cold neutron scattering method, of particle precipitation on the boundary walls, has been investigated. The calculated scattering law as a function of the boundary absorption properties exhibits distinct characteristic which might, under favorable conditions, make such an experimental attempt feasible.(author)

Anomalous vibrational modes in acetanilide: A F.D.S. incoherent inelastic neutron scattering study

International Nuclear Information System (INIS)

Barthes, M.; Moret, J.; Eckert, J.; Johnson, S.W.; Swanson, B.I.; Unkefer, C.J.

1991-01-01

The origin of the anomalous infra-red and Raman modes in acetanilide (C 6 H 5 NHCOCH 3 , or ACN), remains a subject of considerable controversy. One family of theoretical models involves Davydov-like solitons nonlinear vibrational coupling, or ''polaronic'' localized modes. An alternative interpretation of the extra-bands in terms of a Fermi resonance was proposed and recently the existence of slightly non-degenerate hydrogen atom configurations in the H-bond was suggested as an explanation for the anomalies. In this paper we report some new results on the anomalous vibrational modes in ACN that were obtained by inelastic incoherent neutron scattering (INS)

High-energy elastic and quasi-elastic deuteron-nucleus scattering

International Nuclear Information System (INIS)

Tekou, Amouzou

1974-01-01

A study is made of deuteron-nucleus elastic and quasi-elastic scattering and the connection between the opaque nucleus model and the Glauber model is pointed out. The contributions to different cross-sections of the collisions in which the nucleus, excited by one of the nucleons of the deuteron, is brought back to the ground state by the other nucleon is analysed. Coherent deuteron disintegration is found to be highly improbable when the target nucleus is heavy and incoherent disintegration accounts for nearly all the deuteron disintegration. Thus a correct comparison between theoretical and experimental data on proton stripping must take the incoherent deuteron disintegration into consideration

Elastic neutron scattering studies at 96 MeV for transmutation.

Science.gov (United States)

Osterlund, M; Blomgren, J; Hayashi, M; Mermod, P; Nilsson, L; Pomp, S; Ohrn, A; Prokofiev, A V; Tippawan, U

2007-01-01

Elastic neutron scattering from (12)C, (14)N, (16)O, (28)Si, (40)Ca, (56)Fe, (89)Y and (208)Pb has been studied at 96 MeV in the10-70 degrees interval, using the SCANDAL (SCAttered Nucleon Detection AssembLy) facility. The results for (12)C and (208)Pb have recently been published, while the data on the other nuclei are under analysis. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. A novel method for normalisation of the absolute scale of the cross section has been used. The estimated normalisation uncertainty, 3%, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. Elastic neutron scattering is of utmost importance for a vast number of applications. Besides its fundamental importance as a laboratory for tests of isospin dependence in the nucleon-nucleon, and nucleon-nucleus, interaction, knowledge of the optical potentials derived from elastic scattering come into play in virtually every application where a detailed understanding of nuclear processes is important. Applications for these measurements are dose effects due to fast neutrons, including fast neutron therapy, as well as nuclear waste incineration and single event upsets in electronics. The results at light nuclei of medical relevance ((12)C, (14)N and (16)O) are presented separately. In the present contribution, results on the heavier nuclei are presented, among which several are of relevance to shielding of fast neutrons.

Dynamics and Structural Details of Amorphous Phases of Ice Determined by Incoherent Inelastic Neutron Scattering

International Nuclear Information System (INIS)

Klug, D.D.; Tulk, C.A.; Svensson, E.C.; Loong, C.

1999-01-01

Incoherent-inelastic neutron scattering data are obtained over the energy range of lattice and internal vibrations of water molecules in phases of ice prepared by pressure-induced amorphization (high-density amorphous ice, hda), by thermal annealing of hda (low-density amorphous ice, lda), and by rapidly cooling water, as well as in ice Ih and Ic . Hydrogen bonding interactions in lda differ significantly from those in the glass obtained by rapid quenching, which has hydrogen-bond interactions characteristic of highly supercooled water. Hydrogen-bond interactions in hda are weaker than in the low-density phases. copyright 1999 The American Physical Society

Plasticization effect of C60 on the fast dynamics of polystyrene and related polymers: an incoherent neutron scattering study

International Nuclear Information System (INIS)

Sanz, Alejandro; Ruppel, Markus; Cabral, Joao T; Douglas, Jack F

2008-01-01

We utilize inelastic incoherent neutron scattering (INS) to quantify how fullerenes affect the 'fast' molecular dynamics of a family of polystyrene related macromolecules. In particular, we prepared bulk nanocomposites of (hydrogenous and ring-deuterated) polystyrene and poly(4-methyl styrene) using a rapid precipitation method where the C 60 relative mass fraction ranged from 0% to 4%. Elastic window scan measurements, using a high resolution (0.9 μeV) backscattering spectrometer, are reported over a wide temperature range (2-450 K). Apparent Debye-Waller (DW) factors 2 >, characterizing the mean-square amplitude of proton displacements, are determined as a function of temperature, T. We find that the addition of C 60 to these polymers leads to a progressive increase in 2 > relative to the pure polymer value over the entire temperature range investigated, where the effect is larger for larger nanoparticle concentration. This general trend seems to indicate that the C 60 nanoparticles plasticize the fast (∼10 -15 s) local (∼1 A) dynamics of these polymer glasses. Generally, we expect nanoparticle additives to affect polymer dynamics in a similar fashion to thin films in the sense that the high interfacial area may cause both a speeding up and slowing down of the glass state dynamics depending on the polymer-surface interaction

The neutron-deuteron elastic scattering angular distribution at 95 MeV

Energy Technology Data Exchange (ETDEWEB)

Mermod, Philippe

2004-04-01

The neutron-deuteron elastic scattering differential cross section has been measured at 95 MeV incident neutron energy, with the Medley setup at TSL in Uppsala. The neutron-proton differential cross section has also been measured for normalization purposes. The data are compared with theoretical calculations to investigate the role of three-nucleon force effects.

Biological growth in bodies with incoherent interfaces

Science.gov (United States)

Swain, Digendranath; Gupta, Anurag

2018-01-01

A general theory of thermodynamically consistent biomechanical-biochemical growth in a body, considering mass addition in the bulk and at an incoherent interface, is developed. The incoherency arises due to incompatibility of growth and elastic distortion tensors at the interface. The incoherent interface therefore acts as an additional source of internal stress besides allowing for rich growth kinematics. All the biochemicals in the model are essentially represented in terms of nutrient concentration fields, in the bulk and at the interface. A nutrient balance law is postulated which, combined with mechanical balances and kinetic laws, yields an initial-boundary-value problem coupling the evolution of bulk and interfacial growth, on the one hand, and the evolution of growth and nutrient concentration on the other. The problem is solved, and discussed in detail, for two distinct examples: annual ring formation during tree growth and healing of cutaneous wounds in animals.

Neutron-proton elastic scattering at high energies

Energy Technology Data Exchange (ETDEWEB)

Saleem, M.; Fazal-e-Aleem (Punjab Univ., Lahore (Pakistan). Dept. of Physics)

1980-09-06

The most recent measurements of the differential and total cross sections of neutron-proton elastic scattering from 70 to 400 GeV/c have been explained by using rho as a simple pole and pomeron as a dipole. The predictions are also made regarding the energy dependence of dip and bump structure in angular distribution.

Neutron elastic scattering at very small angles

CERN Multimedia

2002-01-01

This experiment will measure neutron-proton elastic scattering at very small angles and hence very small four-momentum transfer, |t|. The range of |t| depends on the incident neutron momentum of the events but the geometrical acceptance will cover the angular range 0.025 < $\\Theta_{lab}$ < 1.9 mrad. The higher figure could be extended to 8.4 mrad by changing the geometry of the experiment in a later phase. \\\\ \\\\ The neutron beam will be highly collimated and will be derived from a 400 GeV external proton beam of up to $4 \\times 10^{10}$ protons per pulse in the SPS North Area Hall 1. The hydrogen target will be gaseous, operating at 40 atm. pressure and acts as a multiwire proportional chamber to detect the recoil protons. The forward neutron will be detected and located by interaction in a neutron vertex detector and its energy measured by a conventional steel plate calorimeter. \\\\ \\\\ The experiment will cover the angular region of nucleon-nucleon scattering which is dominated by Coulomb scattering ...

Discerning the neutron density distribution of 208Pb from nucleon elastic scattering

International Nuclear Information System (INIS)

Karataglidis, S.; Amos, K.; University of Melbourne, VIC; Brown, B.A.; Deb, P.K.

2001-01-01

We seek a measure of the neutron density of 208 Pb from analyses of intermediate energy nucleon elastic scattering. The pertinent model for such analyses is based on coordinate space nonlocal optical potentials obtained from model nuclear ground state densities. As a calibration of the use of Skyrme-Hartree-Fock models the elastic scattering from 40 Cawas considered as well. Those potentials give predictions of integral observables and of angular distributions which show sensitivity to the neutron density. When compared with experiment, and correlated with analyses of electron scattering data, the results suggest that 208 Pb has a neutron skin thickness ∼ 0.17 fm

A quasi-elastic neutron scattering and neutron spin-echo study of hydrogen bonded system

Energy Technology Data Exchange (ETDEWEB)

Branca, C.; Faraone, A.; Magazu, S.; Maisano, G.; Mangione, A

2004-07-15

This work reports neutron spin echo results on aqueous solutions of trehalose, a naturally occurring disaccharide of glucose, showing an extraordinary bioprotective effectiveness against dehydration and freezing. We collected data using the SPAN spectrometer (BENSC, Berlin) on trehalose aqueous solutions at different temperature values. The obtained findings are compared with quasi-elastic neutron scattering results in order to furnish new results on the dynamics of the trehalose/water system on the nano and picoseconds scale.

Time collimation for elastic neutron scattering instrument at a pulsed source

International Nuclear Information System (INIS)

Aksenov, V.L.; Nikitenko, Yu.V.

1996-01-01

Conditions for carrying out elastic neutron scattering experiments using the time-of-flight technique are considered. It is shown that the employment of time dependent neutron beam collimation in the source-sample flight path increases the luminosity of the spectrometer under certain resolution restrictions. 3 refs., 8 figs

Fast-neutron elastic scattering from elemental vanadium

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.; Lawson, R.D.

1988-03-01

Differential neutron elastic- and inelastic-scattering cross sections of vanadium were measured from 4.5 to 10 MeV. These results were combined with previous 1.5 to 4.0 MeV data from this laboratory, the 11.1 MeV elastic-scattering results obtained at Ohio University, and the reported neutron total cross sections to energies of ∼20.0 MeV, to form a data base which was interpreted in terms of the spherical optical-statistical model. A fit to the data was achieved by making both the strengths and geometries of the optical-model potential energy dependent. This energy dependence was large below ∼6.0 MeV. Above ∼6.0 MeV the energy dependencies are smaller, and similar to those characteristic of global models. Using the dispersion relationship and the method of moments, the optical-model potential energy deduced from 0.0 to 11.1 MeV neutron-scattering data was extrapolated to higher energies and to the bound-state regime. This extrapolation leads to predicted neutron total cross sections that are within 3% of the experimental values throughout the energy range 0.0 to 20.0 MeV. Furthermore, the values of the volume-integral-per-nucleon of the real potential are in excellent agreement with those needed to reproduce the observed binding energies of particle- and hole-states. The latter gives clear evidence of the Fermi surface anomaly. Using only the 0.0 to 11.1 MeV data, the predicted E < O behavior of the strength and radius of the real shell-model Woods-Saxon potential are somewhat different from those obtained by Mahaux and Sartor in their analysis of nuclei near closed shells. 61 refs., 9 figs., 2 tabs

The polarization of MeV neutrons elastically scattered from 4He

International Nuclear Information System (INIS)

Bond, J.E.; Firk, F.W.K.

1976-01-01

The analyzing power of 4 He for neutron elastic scattering has been measured at four angles between 20 0 and 80 0 (lab) throughout the energy range 1.5-6.0 MeV using a double-scattering method. The intense flux of polarized neutrons was generated via the reactions Pb(γ, n)→ 12 C(n, n(pol.) 12 C, and the magnitude of the polarization of the neutron beam measured absolutely in a separate double-scattering experiment. Neutron energies were determined with a nanosecond time-of-flight spectrometer, and the generalized neutron spin-precession method was used to minimize systematic uncertainties. (Auth.)

Suppression of tunnel modes of hydrogen in α-Mn by elastic stresses

International Nuclear Information System (INIS)

Antonov, V.E.; Fedotov, V.K.; Glazkov, V.P.; Somenkov, V.A.; Kozlenko, D.P.; Savenko, B.N.

2002-01-01

By means of inelastic incoherent scattering of neutrons one investigated into behavior of hydrogen tunnel mode in MnH 0.04 and MnH 0.07 under high pressure values in sapphire anvils. Peak of inelastic scattering relevant to hydrogen tunnelling in a two-hole potential was determined to vanish at 0.8 GPa pressure under quasi-hydrostatic mode and to survive with no visible changes under standard hydrostatics. The detected effect of suppression of tunnel modes by inhomogeneous elastic stresses is explained by interruption of levels in neighboring holes by static shifts [ru

Quasielastic neutron scattering study of large amplitude motions in molecular systems

International Nuclear Information System (INIS)

Bee, M.

1996-01-01

This lecture aims at giving some illustrations of the use of Incoherent Quasielastic Neutron Scattering in the investigation of motions of atoms or molecules in phases with dynamical disorder. The general incoherent scattering function is first recalled. Then the Elastic Incoherent Structure Factor is introduced. It is shown how its determination permits to deduce a particular dynamical model. Long-range translational diffusion is illustrated by some experiments carried out with liquids or with different chemical species intercalated in porous media. Examples of rotational motions are provided by solid phases where an orientational disorder of the molecules exists. The jump model is the most commonly used and yields simple scattering laws which can be easily handled. Highly disordered crystals require a description in terms of the isotropic rotational diffusion model. Many of the present studies are concerned with rather complicated systems. Considerable help is obtained either by using selectively deuterated samples or by carrying out measurements with semi-oriented samples. (author) 5 figs., 14 refs

Some neutron scattering studies on magnetic and molecular phase transitions

International Nuclear Information System (INIS)

Bevaart, L.

1978-01-01

In this thesis neutron-scattering investigations on two different systems are described. The first study is concerned with the magnetic ordering phenomena in pseudo two-dimensional (d = 2), two-component antiferromagnets K 2 Mnsub(1-x)Msub(x)F 4 (M = Fe, Co), as a function of the composition x and temperature T. For one of the samples in this series, K 2 Musub(0.978)Fesub(0.022)F 4 , the influence of an external magnetic field on the ordering characteristics was studied in addition. The second study deals with the rotational motions of the NH 4 + groups in NH 4 ZnF 3 in relation with the structural phase transition at Tsub(c) = 115.1 K. The experimental techniques were chosen according to the requirements of each of these two subjects. The former study was carried out by observing the elastic magnetic neutron scattering with a double-axis diffractometer, whereas for the latter study time-of-flight (TOF) techniques were applied to observe the inelastic and quasi-elastic incoherent neutron scattering by the protons of the rotating NH 4 + groups. (Auth.)

Quasi-elastic neutron line broadening in nematic liquid crystals

International Nuclear Information System (INIS)

Cvikl, B.; Dimic, V.; Dusic, M.; Kristof, E.; Srebotnjak, E.

1979-01-01

On the basis of a new random walk torsional oscillations model of the amplitude φ 0 of rigid flat molecules a quasi-elastic neutron line broadening has been calculated and the results compared to the measurements obtained on the sample of cholesteryl propionate. A good agreement was obtained. (author)

Fast Neutron Elastic and Inelastic Scattering of Vanadium

Energy Technology Data Exchange (ETDEWEB)

Holmqvist, B; Johansson, S G; Lodin, G; Wiedling, T

1969-11-15

Fast neutron scattering interactions with vanadium were studied using time-of-flight techniques at several energies in the interval 1.5 to 8.1 MeV. The experimental differential elastic scattering cross sections have been fitted to optical model calculations and the inelastic scattering cross sections have been compared with Hauser-Feshbach calculations, corrected for the fluctuation of compound-nuclear level widths.

Geometry Survey of the Time-of-Flight Neutron-Elastic Scattering (Antonella) Experiment

Energy Technology Data Exchange (ETDEWEB)

Oshinowo, Babatunde O. [Fermilab; Izraelevitch, Federico [Buenos Aires U.

2016-10-17

The Antonella experiment is a measurement of the ionization efficiency of nuclear recoils in silicon at low energies [1]. It is a neutron elastic scattering experiment motivated by the search for dark matter particles. In this experiment, a proton beam hits a lithium target and neutrons are produced. The neutron shower passes through a collimator that produces a neutron beam. The beam illuminates a silicon detector. With a certain probability, a neutron interacts with a silicon nucleus of the detector producing elastic scattering. After the interaction, a fraction of the neutron energy is transferred to the silicon nucleus which acquires kinetic energy and recoils. This kinetic energy is then dissipated in the detector producing ionization and thermal energy. The ionization produced is measured with the silicon detector electronics. On the other hand, the neutron is scattered out of the beam. A neutron-detector array (made of scintillator bars) registers the neutron arrival time and the scattering angle to reconstruct the kinematics of the neutron-nucleus interaction with the time-of-flight technique [2]. In the reconstruction equations, the energy of the nuclear recoil is a function of the scattering angle with respect to the beam direction, the time-of-flight of the neutron and the geometric distances between components of the setup (neutron-production target, silicon detector, scintillator bars). This paper summarizes the survey of the different components of the experiment that made possible the off-line analysis of the collected data. Measurements were made with the API Radian Laser Tracker and I-360 Probe Wireless. The survey was completed at the University of Notre Dame, Indiana, USA in February 2015.

Neutron-proton elastic scattering between 200 and 500 MeV

International Nuclear Information System (INIS)

Clough, A.S.; Gibson, D.R.; Axen, D.

1979-01-01

Measurements over an extensive angular range of the Dsub(t) and P parameters in free neutron-proton elastic scattering at laboratory energies of 220, 325, 425 and 495 MeV are reported. Experimental and analytical details are given. (author)

New developments in neutron scattering for the study of molecular systems: structure and diffusive motions

International Nuclear Information System (INIS)

Volino, F.

1976-01-01

After a short review of the main concepts concerning the neutron and its interaction with matter, the authors focus their attention on the study of molecular systems by means of neutron scattering. Instead of reviewing the subject yet again, they limit themselves to the new kind of work which can be done now, with the combined help of high flux reactors and novel instruments. As examples, a few experiments performed at the Institut Laue-Langevin in Grenoble are described: a neutron diffraction study of liquid acetonitrile using a powder diffractometer installed at the hot source; three high-resolution quasi-elastic studies of molecular motions - in an organic solid, (PAA), an organic liquid (C 3 H 6 ) and a liquid crystal (TBBA) - made by combining measurements with high and ultra-high energy resolution spectrometers installed at the cold source. The concept of elastic incoherent structure factor (EISF) is extensively used for the analysis. Finally some prospects on possible future developments are presented. (orig./HK) [de

Monitoring elastic strain and damage by neutron and synchrotron beams

International Nuclear Information System (INIS)

Withers, P.J.

2001-01-01

Large-scale neutron and synchrotron X-ray facilities have been providing important information for physicists and chemists for many decades. Increasingly, materials engineers are finding that they can also provide them with important information non-destructively. Highly penetrating neutron and X-ray synchrotron beams provide the materials engineer with a means of obtaining information about the state of stress and damage deep within materials. In this paper the principles underlying the elastic strain measurement and damage characterization techniques are introduced. (orig.)

np Elastic-scattering experiments with polarized neutron beams

International Nuclear Information System (INIS)

Chalmers, J.S.; Ditzler, W.R.; Hill, D.

1985-01-01

Measurements of the spin transfer parameters, K/sub NN/ and K/sub LL/, at 500, 650, and 800 MeV are presented for the reaction p-vector d → n-vector pp at 0 0 . The data are useful input to the NN data base and indicate that the quasi-free charge exchange (CEX) reaction is a useful mechanism for producing neutrons with at least 40% polarization at energies as low as 500 MeV. Measurements of np elastic scattering observables C/sub LL/ and C/sub SL/ covering 35 0 to 172 0 are performed using a polarized neutron beam at 500, 650, and 800 MeV. Preliminary results are presented. 3 refs., 6 figs

Fast, quantitative, and nondestructive evaluation of hydrided LWR fuel cladding by small angle incoherent neutron scattering of hydrogen

Energy Technology Data Exchange (ETDEWEB)

Yan, Y.; Qian, S.; Littrell, K.; Parish, C.M. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Plummer, L.K. [University of Oregon, Eugene, OR 97403 (United States)

2015-05-15

A nondestructive neutron scattering method to precisely measure the uptake of hydrogen and the distribution of hydride precipitates in light water reactor (LWR) fuel cladding was developed. Zircaloy-4 cladding used in commercial LWRs was used to produce hydrided specimens. The hydriding apparatus consists of a closed stainless-steel vessel that contains Zr alloy specimens and hydrogen gas. Following hydrogen charging, the hydrogen content of the hydrided specimens was measured using the vacuum hot extraction method, by which the samples with desired hydrogen concentrations were selected for the neutron study. Optical microscopy shows that our hydriding procedure results in uniform distribution of circumferential hydrides across the wall thickness. Small angle neutron incoherent scattering was performed in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Our study demonstrates that the hydrogen in commercial Zircaloy-4 cladding can be measured very accurately in minutes by this nondestructive method over a wide range of hydrogen concentrations from a very small amount (≈20 ppm) to over 1000 ppm. The hydrogen distribution in a tube sample was obtained by scaling the neutron scattering rate with a factor determined by a calibration process using standard, destructive direct chemical analysis methods on the specimens. This scale factor can be used in future tests with unknown hydrogen concentrations, thus providing a nondestructive method for determining absolute hydrogen concentrations.

Polarisation analysis of elastic neutron scattering using a filter spectrometer on a pulsed source

International Nuclear Information System (INIS)

Mayers, J.; Williams, W.G.

1981-05-01

The experimental and theoretical aspects of the polarisation analysis technique in elastic neutron scattering are described. An outline design is presented for a filter polarisation analysis spectrometer on the Rutherford Laboratory Spallation Neutron Source and estimates made of its expected count rates and resolution. (author)

New Model to describe the interaction of slow neutrons with solid deuterium

International Nuclear Information System (INIS)

Granada, J.R

2009-01-01

A new scattering kernel to describe the interaction of slow neutrons with solid Deuterium was developed. The main characteristics of that system are contained in the formalism, including the lattice s density of states, the Young-Koppel quantum treatment of the rotations, and the internal molecular vibrations. The elastic processes involving coherent and incoherent contributions are fully described, as well as the spin-correlation effects. The results from the new model are compared with the best available experimental data, showing very good agreement. [es

Diffraction plane dependency of elastic constants in ferritic steel in neutron stress measurement

International Nuclear Information System (INIS)

Hayashi, M.; Ishiwata, M.; Minakawa, N.; Funahashi, S.

1993-01-01

Neutron diffraction measurements have been made to investigate the elastic properties of the ferritic steel obtained from socket weld. The Kroner elastic model is found to account for the [hkl]-dependence of Young's modulus and Poisson's ratio in the material. Maps of residual stress are later to be made by measuring lattice strain from shifts in the (112) diffraction peak, for which the diffraction elastic constants the herein found to be E=243±5GPa and ν=0.28±0.01. (author)

Development of Cold Neutron Scattering Kernels for Advanced Moderators

International Nuclear Information System (INIS)

Granada, J. R.; Cantargi, F.

2010-01-01

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 compared predicted total cross sections with experimental data obtained in our laboratory. In addition, we have introduced a new model to describe the interaction of slow neutrons with solid methane in phase II (stable phase below T = 20.4 K, atmospheric pressure). Very recently, a new scattering kernel to describe the interaction of slow neutrons with solid Deuterium was also developed. The main dynamical characteristics of that system are contained in the formalism, the elastic processes involving coherent and incoherent contributions are fully described, as well as the spin-correlation effects.

Note on the elastic-scattering of few-MeV neutrons from elemental calcium

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.

1982-03-01

Neutron differential-elastic-scattering cross sections of elemental calcium are measured from 0 . Incident-neutron energy resolutions are approximately 50 to 100 keV. The experimental results are compared with values given in ENDF/B-V and are examined in the context of shielding applications. An optical potential is deduced from the measured values and its possible implications are discussed

Tidal deformations of neutron stars: The role of stratification and elasticity

International Nuclear Information System (INIS)

Penner, A. J.; Andersson, N.; Hawke, I.; Jones, D. I.; Samuelsson, L.

2011-01-01

We discuss the response of neutron stars to the tidal interaction in a compact binary system, as encoded in the Love number associated with the induced deformation. This problem is of interest for gravitational-wave astronomy as there may be a detectable imprint on the signal from the late stages of binary coalescence. Previous work has focused on simple barotropic neutron star models, providing an understanding of the role of the stellar compactness and overall density profile. We add realism to the discussion by developing the framework required to model stars with varying composition and an elastic crust. These effects are not expected to be significant for the next generation of detectors, but it is nevertheless useful to be able to quantify them. Our results show that (perhaps surprisingly) internal stratification has no impact whatsoever on the Love number. We also show that crust elasticity provides a (predictably) small correction to existing models.

Separation of coherent and incoherent scattering in liquid para-H{sub 2} by polarisation analysis

Energy Technology Data Exchange (ETDEWEB)

Garcia-Hernandez, M; Mompean, F J [Madrid Univ. (Spain); Schaerpf, O; Andersen, K H [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Fak, B [CEA Centre d` Etudes de Grenoble, 38 (France)

1997-04-01

In the 1960 IAEA Symposium on Neutron Scattering, Sarma presented his theoretical study on the scattering of cold neutrons by liquid hydrogen and demonstrated how the intimate coupling between nuclear and rotational degrees of freedom finally results in the possibility of observing collective modes from this material, which to many neutron scatterers is synonymous with `incoherent`. This problem is investigated with polarised neutrons to gain access to a limited region of the (Q,E) space where the collective response from this liquid is found. (author).

Diffraction and single-crystal elastic constants of Inconel 625 at room and elevated temperatures determined by neutron diffraction

International Nuclear Information System (INIS)

Wang, Zhuqing; Stoica, Alexandru D.; Ma, Dong; Beese, Allison M.

2016-01-01

In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.

Diffraction and single-crystal elastic constants of Inconel 625 at room and elevated temperatures determined by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhuqing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Stoica, Alexandru D. [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Ma, Dong, E-mail: dongma@ornl.gov [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Beese, Allison M., E-mail: amb961@psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

2016-09-30

In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.

Polarized Neutron Scattering

OpenAIRE

Roessli, B.; Böni, P.

2000-01-01

The technique of polarized neutron scattering is reviewed with emphasis on applications. Many examples of the usefulness of the method in various fields of physics are given like the determination of spin density maps, measurement of complex magnetic structures with spherical neutron polarimetry, inelastic neutron scattering and separation of coherent and incoherent scattering with help of the generalized XYZ method.

Fast-neutron elastic-scattering cross sections of elemental tin

International Nuclear Information System (INIS)

Budtz-Jorgensen, C.; Guenther, P.T.; Smith, A.

1982-07-01

Broad-resolution neutron-elastic-scattering cross sections of elemental tin are measured from 1.5 to 4.0 MeV. Incident-energy intervals are approx. 50 keV below 3.0 MeV and approx. 200 keV at higher energies. Ten to twenty scattering angles are used, distributed between approx. 20 and 160 0 . The experimental results are used to deduce the parameters of a spherical optical-statistical model and they are also compared with corresponding values given in ENDF/B-V

Dynamically polarized samples for neutron protein crystallography at the Spallation Neutron Source

International Nuclear Information System (INIS)

Zhao, Jinkui; Pierce, Josh; Robertson, J. L.; Herwig, Kenneth W.; Myles, Dean; Cuneo, Matt; Li, Le; Meilleur, Flora; Standaert, Bob

2016-01-01

To prepare for the next generation neutron scattering instruments for the planned second target station at the Spallation Neutron Source (SNS) and to broaden the scientific impact of neutron protein crystallography at the Oak Ridge National Laboratory, we have recently ramped up our efforts to develop a dynamically polarized target for neutron protein crystallography at the SNS. Proteins contain a large amount of hydrogen which contributes to incoherent diffraction background and limits the sensitivity of neutron protein crystallography. This incoherent background can be suppressed by using polarized neutron diffraction, which in the same time also improves the coherent diffraction signal. Our plan is to develop a custom Dynamic Nuclear Polarization (DNP) setup tailored to neutron protein diffraction instruments. Protein crystals will be polarized at a magnetic field of 5 T and temperatures of below 1 K. After the dynamic polarization process, the sample will be brought to a frozen-spin mode in a 0.5 T holding field and at temperatures below 100 mK. In a parallel effort, we are also investigating various ways of incorporating polarization agents needed for DNP, such as site specific spin labels, into protein crystals. (paper)

SCANDAL -- A facility for elastic neutron scattering studies in the 50--130 MeV range

International Nuclear Information System (INIS)

Klug, J.; Blomgren, J.; Atac, A.; Bergenwall, B.; Dangtip, S.; Elmgren, K.; Johansson, C.; Olsson, N.; Prokofiev, A.V.; Rahm, J.; Oberstedt, A.; Tovesson, F.; Eudes, Ph.; Haddad, F.; Kerveno, M.; Kirchner, T.; Lebrun, C.; Stuttge, L.; Slypen, I.; Michel, R.; Neumann, S.; Herpers, U.

2001-01-01

A facility for detection of scattered neutrons in the energy interval 50--130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has recently been installed at the 20--180 MeV neutron beam facility of the The Svedberg Laboratory, Uppsala. It is primarily intended for studies of elastic neutron scattering, but can be used for the (n,p) and (n,d) reaction experiments as well. The performance of the spectrometer is illustrated in measurements of the (n,p) and (n,n) reactions on 1 H and 12 C. In addition, the neutron beam facility is described in some detail

SCANDAL--a facility for elastic neutron scattering studies in the 50-130 MeV range

CERN Document Server

Klug, J; Atac, A; Bergenwall, B; Dangtip, S; Elmgren, K; Johansson, C; Olsson, N; Pomp, S; Prokofiev, A V; Rahm, J; Tippawan, U; Jonsson, O; Nilsson, L; Renberg, P U; Nadel-Turonski, P; Ringbom, A; Oberstedt, A; Tovesson, F; Blideanu, V; Le Brun, C; Lecolley, J F; Lecolley, F R; Louvel, M; Marie, N; Schweitzer, C; Varignon, C; Eudes, P; Haddad, F; Kerveno, M; Kirchner, T; Lebrun, C; Stuttgé, L; Slypen, I; Smirnov, A N; Michel, R; Neumann, S; Herpers, U

2002-01-01

A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCAttered Nucleon Detection AssembLy (SCANDAL), has recently been installed at the 20-180 MeV neutron beam facility of The Svedberg Laboratory, Uppsala. It is primarily intended for studies of elastic neutron scattering, but can be used for (n,p) and (n,d) reaction experiments as well. The performance of the spectrometer is illustrated in measurements of the (n,p) and (n,n) reactions on sup 1 H and sup 1 sup 2 C. In addition, the neutron beam facility is described in some detail.

Interpretation of the quasi-elastic neutron scattering on PAA by rotational diffusion models

International Nuclear Information System (INIS)

Bata, L.; Vizi, J.; Kugler, S.

1974-10-01

First the most important data determined by other methods for para azoxy anisolon (PAA) are collected. This molecule makes a rotational oscillational motion around the mean molecular direction. The details of this motion can be determined by inelastic neutron scattering. Quasielastic neutron scattering measurements were carried out without orienting magnetic field on a time-of-flight facility with neutron beam of 4.26 meV. For the interpretation of the results two models, the spherical rotation diffusion model and the circular random walk model are investigated. The comparison shows that the circular random walk model (with N=8 sites, d=4A diameter and K=10 10 s -1 rate constant) fits very well with the quasi-elastic neutron scattering, while the spherical rotational diffusion model seems to be incorrect. (Sz.N.Z.)

Determination of the fast neutrons spectra by the Elastic scattering method (n, p)

International Nuclear Information System (INIS)

Elizalde D, J.

1973-01-01

This work consists in determining the fast neutron spectra emitted by a Pu-Be isotopic source. The implemented technique is based in the spectrometry (n, p). This consists in making to fall on a fast neutrons beams (polyenergetic) over a thin film of hydrogenated material, detecting the spectra of emitted protons at a fix angle. The polyethylene film and the used solid state detector are inside of a vacuum chamber. The detector is placed at 30 degree with respect to direction of the incident neutrons beam. The protons spectra is stored in a multichannel. the energy is obtained with the prior calibration of the system. The data processing involves the transformation of the protons spectra observed at the falling on neutrons spectra over the film. The energy of the neutrons is related with that of the protons, according to the collision kinematical equations. The cross section of elastic collision of the neutrons with the hydrogen atoms is obtained from literature. Applying these relations to the observed spectra it is obtained the falling on neutron spectra over the film. (Author)

Elastic neutron diffuse scattering in Zr(Ca, Y)O2-x

International Nuclear Information System (INIS)

Barberis, P.; Beuneu, B.; Novion, C.H. de.

1990-01-01

Elastic neutron diffuse scattering has been measured in cubic Zr(Ca, Y)O 2-x at room temperature. The very high diffuse scattering (up to 70 Laue) is explained mostly by the oxygen displacements along directions, and by Ca displacements along . The weak short-range order contribution strongly suggests that oxygen vacancies tend to place as second rather than at first neighbours of a Ca stabilizing ion

Incoherent inelastic neutron scattering measurements on ice VII: Are there two kinds of hydrogen bonds in ice?

International Nuclear Information System (INIS)

Klotz, S.; Strassle, Th.; Philippe, J.; Salzmann, C.G.; Parker, S.F.

2005-01-01

We report the vibrational spectrum of recovered ice VII measured by inelastic incoherent neutron scattering and compare this to similar data of its fully hydrogen-ordered form, ice VIII, under exactly the same conditions (15 K, 1 bar). The spectra of the two phases have their principal features at similar energies, in both the translational and vibrational bands, with a substantial disorder-related broadening in ice VII. In particular, we find no evidence for a peak at 49 meV in ice VII which earlier was associated with the possible existence of two kinds of hydrogen bonds. Additional Raman measurements in ice VII and ice VIII show that the O-H stretching frequencies in the two phases are almost identical. Therefore, the presence of split molecular-optic bands in ice phases, including ordinary ice Ih, is likely related to an incomplete description of the phonon dispersion rather than to a fundamentally new feature in the nature of the hydrogen bond. (authors)

Introductory theory of neutron scattering

International Nuclear Information System (INIS)

Gunn, J.M.F.

1986-12-01

The paper comprises a set of six lecture notes which were delivered to the summer school on 'Neutron Scattering at a pulsed source', Rutherford Laboratory, United Kingdom, 1986. The lectures concern the physical principles of neutron scattering. The topics of the lectures include: diffraction, incoherent inelastic scattering, connection with the Schroedinger equation, magnetic scattering, coherent inelastic scattering, and surfaces and neutron optics. (UK)

Quasi-elastic (QENS) and inelastic neutron scattering (INS) on hexamethylbenzene

Energy Technology Data Exchange (ETDEWEB)

Krawczyk, J. [H. Niewodniczanski Institute of Nuclear Physics PAN, NZ3, ul. Radzikowskiego 152, 31-342 Cracow (Poland)]. E-mail: jan.krawczyk@ifj.edu.pl; Mayer, J. [H. Niewodniczanski Institute of Nuclear Physics PAN, NZ3, ul. Radzikowskiego 152, 31-342 Cracow (Poland); Natkaniec, I. [H. Niewodniczanski Institute of Nuclear Physics PAN, NZ3, ul. Radzikowskiego 152, 31-342 Cracow (Poland): Frank Laboratory of Neutron Physics, JINR, 141980 Dubna, Russia (Russian Federation); Nowina Konopka, M. [H. Niewodniczanski Institute of Nuclear Physics PAN, NZ3, ul. Radzikowskiego 152, 31-342 Cracow (Poland); Pawlukojc [Frank Laboratory of Neutron Physics, JINR, 141980 Dubna, Russia (RU): Institute of Nuclear Chemistry and Technology, 03-195 Warszawa (Poland); Steinsvoll, O. [Institute for Energy Technology, 2007 Kjeller (Norway); Janik, J.A. [H. Niewodniczanski Institute of Nuclear Physics PAN, NZ3, ul. Radzikowskiego 152, 31-342 Cracow (Poland)

2005-05-15

The Quasi-elastic Neutron scattering (QENS) spectra of polycrystalline hexamethylbenzene (HMB) were measured for temperatures from 10K to room temperature (phase III and phase II) for momentum transfer 1.9A{sup -1}. The Inelastic Neutron scattering (INS) and QENS spectra for momentum transfer 0.5-2.9A{sup -1} were measured at T=20, 100 and 130K for energy transfer up to 200meV. The low-resolution diffraction patterns, used as the phase indicator, were also obtained. In the phase III (below 117K), we see practically no quasi-elastic broadening. In phase II, the broadening changes with the temperature are in good agreement with the Arrhenius law. The estimated activation barrier to reorientation is 6kJ/mol. The fitted mean time between instantaneous 120{sup o} jumps of CH{sub 3} groups changes from 10{sup -11}s at T=130K to 2x10{sup -13}s at room temperature. On the basis of EISF versus momentum transfer dependency it is hardly possible to decide what is the geometry of the reorientation. Both reorientation of the CH{sub 3} groups around the three-fold symmetry axis and reorientation of the whole molecule around the six-fold symmetry axis of the benzene ring could describe our results, the former being more probable. The measured INS spectra are compared with the quantum chemical ab initio calculations performed for an isolated HMB molecule.

Quasi-elastic (QENS) and inelastic neutron scattering (INS) on hexamethylbenzene

International Nuclear Information System (INIS)

Krawczyk, J.; Mayer, J.; Natkaniec, I.; Nowina Konopka, M.; Pawlukojc; Steinsvoll, O.; Janik, J.A.

2005-01-01

The Quasi-elastic Neutron scattering (QENS) spectra of polycrystalline hexamethylbenzene (HMB) were measured for temperatures from 10K to room temperature (phase III and phase II) for momentum transfer 1.9A -1 . The Inelastic Neutron scattering (INS) and QENS spectra for momentum transfer 0.5-2.9A -1 were measured at T=20, 100 and 130K for energy transfer up to 200meV. The low-resolution diffraction patterns, used as the phase indicator, were also obtained. In the phase III (below 117K), we see practically no quasi-elastic broadening. In phase II, the broadening changes with the temperature are in good agreement with the Arrhenius law. The estimated activation barrier to reorientation is 6kJ/mol. The fitted mean time between instantaneous 120 o jumps of CH 3 groups changes from 10 -11 s at T=130K to 2x10 -13 s at room temperature. On the basis of EISF versus momentum transfer dependency it is hardly possible to decide what is the geometry of the reorientation. Both reorientation of the CH 3 groups around the three-fold symmetry axis and reorientation of the whole molecule around the six-fold symmetry axis of the benzene ring could describe our results, the former being more probable. The measured INS spectra are compared with the quantum chemical ab initio calculations performed for an isolated HMB molecule

Analysis of the angular distributions of elastically scattered neutrons for 235U

International Nuclear Information System (INIS)

Sukhovitskij, E.Sh.; Benderskij, A.R.; Konshin, V.A.

1976-01-01

Experimental data on the angular distributions of 0.5-15 MeV neutrons elastically scattered by 235 U nuclei are analysed on the basis of Bessel functions and Legendre polynomial expansions. The advantages of the method are that there are no negative cross-sections and relatively few expansion coefficients and that experimental data on scattering at 0 0 and 180 0 are not needed. (author)

Neutron Elastic Scattering Cross Sections Experimental Data and Optical Model Cross Section Calculations. A Compilation of Neutron Data from the Studsvik Neutron Physics Laboratory

Energy Technology Data Exchange (ETDEWEB)

Holmqvist, B; Wiedling, T

1969-06-15

Neutron elastic scattering cross section measurements have been going on for a long period at the Studsvik Van de Graaff laboratory. The cross sections of a range of elements have been investigated in the energy interval 1.5 to 8 MeV. The experimental data have been compared with cross sections calculated with the optical model when using a local nuclear potential.

Fast-neutron total and elastic-scattering cross sections of elemental indium

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-11-01

Broad-resolution neutron total cross sections of elemental indium were measured from 0.8 to 4.5 MeV. Differential-elastic-scattering cross sections were measured from approx. = 1.5 to 3.8 MeV at intervals of approx. = 50 to 200 keV and at scattering angles in the range 20 to 160 degrees. The experimental results are interpreted in terms of the optical-statistical model and are compared with respective values given in ENDF/B-V

Elastic scattering of polarized neutrons by 3He at low energy

International Nuclear Information System (INIS)

Drigo, L.; Tornielli, G.; Zannoni, G.

1982-01-01

Elastic scattering by 3 He for 1.67, 2.43, 3.0, 3.4 and 7.8 MeV neutron beams of known polarization was measured at seven angles from 25 0 to 155 0 using a high pressure gas scintillation counter. The geometrical and multiple scattering effects were accounted for by the Monte Carlo technique. The corrected results were compared with previous experimental data and with the existing predictions based on microscopic calculations and phenomenological analyses. (author)

Elastic Neutron Scattering at 96 MeV from {sup 12}C and {sup 208}Pb

Energy Technology Data Exchange (ETDEWEB)

Klug, J.; Blomgren, J.; Atac, A. [and others

2003-04-01

A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has recently been installed at the 20-180 MeV neutron beam line of the The Svedberg Laboratory, Uppsala. Elastic neutron scattering from {sup 12}C and {sup 208}Pb has been studied at 96 MeV in the 10-70 deg interval. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated uncertainty, 3 %, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions, based on phenomenology or microscopic nuclear theory.

Experimental verification of a method to create a variable energy neutron beam from a monoenergetic, isotropic source using neutron elastic scatter and time of flight

Energy Technology Data Exchange (ETDEWEB)

Whetstone, Zachary D., E-mail: zacwhets@umich.edu; Flaska, Marek, E-mail: mflaska@umich.edu; Kearfott, Kimberlee J., E-mail: kearfott@umich.edu

2016-08-11

An experiment was performed to determine the neutron energy of near-monoergetic deuterium–deuterium (D–D) neutrons that elastically scatter in a hydrogenous target. The experiment used two liquid scintillators to perform time of flight (TOF) measurements to determine neutron energy, with the start detector also serving as the scatter target. The stop detector was placed 1.0 m away and at scatter angles of π/6, π/4, and π/3 rad, and 1.5 m at a scatter angle of π/4 rad. When discrete 1 ns increments were implemented, the TOF peaks had estimated errors between −21.2 and 3.6% relative to their expected locations. Full widths at half-maximum (FWHM) ranged between 9.6 and 20.9 ns, or approximately 0.56–0.66 MeV. Monte Carlo simulations were also conducted that approximated the experimental setup and had both D–D and deuterium–tritium (DT) neutrons. The simulated results had errors between −17.2 and 0.0% relative to their expected TOF peaks when 1 ns increments were applied. The largest D–D and D–T FWHMs were 26.7 and 13.7 ns, or approximately 0.85 and 4.98 MeV, respectively. These values, however, can be reduced through manipulation of the dimensions of the system components. The results encourage further study of the neutron elastic scatter TOF system with particular interest in application to active neutron interrogation to search for conventional explosives.

The effect of the new nucleon-nucleus elastic scattering data in LAHET trademark Version 2.8 on neutron displacement cross section calculations

International Nuclear Information System (INIS)

Pitcher, E.J.; Ferguson, P.D.; Russell, G.J.; Prael, R.E.; Madland, D.G.; Court, J.D.; Daemen, L.L.; Wechsler, M.S.

1997-01-01

The latest release of the medium-energy Monte Carlo transport code LAHET includes a new nucleon-nucleus elastic scattering treatment based on a global medium-energy phenomenological optical-model potential. Implementation of this new model in LAHET allows nuclear elastic scattering for neutrons with energies greater than 15 MeV and for protons with energies greater than 50 MeV. Previous investigations on the impact of the new elastic scattering data revealed that the addition of the proton elastic scattering channel can lead to a significant increase in the calculated damage energy under certain conditions. The authors report here results on the impact of the new elastic scattering data on calculated displacement cross sections in various elements for neutrons with energies in the range 16 to 3,160 MeV. Calculated displacement cross sections at 20 MeV in low-mass materials are in better agreement with SPECTER-calculated cross sections

Study of thermodynamic stabilities of polytypes of n-C36H74 by solubility measurements and incoherent inelastic neutron scattering

Science.gov (United States)

Kubota, Hideki; Kaneko, Fumitoshi; Kawaguchi, Tatsuya

2005-01-01

The thermodynamic properties of the two polytypes of n-hexatriacontane (n-C36H74), single-layered structure Mon and double-layered structure Orth II have been investigated by means of solubility measurements and incoherent inelastic neutron scattering. The solubility measurements reveal that Orth II is more stable than Mon by 1.2 kJ/mol because of the advantage of larger entropy. The neutron scattering measurements show that the vibrational modes of Orth II shift to the lower frequencies compared with those of Mon in the frequency region below 120 cm-1. The advantage of Orth II in vibrational entropy due to the low-frequency shifts is estimated to be 9.6 J K-1/mol at 288 K under the harmonic approximation, which nearly agrees with the entropy difference of 6.8 J K-1/mol between Mon and Orth II determined by solubility measurements. These results suggest that the difference in vibrational entropy due to low-frequency modes mainly contributes to the relative thermodynamic stabilities of polytypic structures of long-chain compounds. From the frequency of methyl torsional mode, it is suggested that the cohesive force at the lamellar interface is stronger in Mon than in Orth II.

54Fe neutron elastic and inelastic scattering differential cross sections from 2-6 MeV

Science.gov (United States)

Vanhoy, J. R.; Liu, S. H.; Hicks, S. F.; Combs, B. M.; Crider, B. P.; French, A. J.; Garza, E. A.; Harrison, T.; Henderson, S. L.; Howard, T. J.; McEllistrem, M. T.; Nigam, S.; Pecha, R. L.; Peters, E. E.; Prados-Estévez, F. M.; Ramirez, A. P. D.; Rice, B. G.; Ross, T. J.; Santonil, Z. C.; Sidwell, L. C.; Steves, J. L.; Thompson, B. K.; Yates, S. W.

2018-04-01

Measurements of neutron elastic and inelastic scattering cross sections from 54Fe were performed for nine incident neutron energies between 2 and 6 MeV. Measured differential scattering cross sections are compared to those from previous measurements and the ENDF, JENDL, and JEFF data evaluations. TALYS calculations were performed and modifications of the default parameters are found to better describe the experimental cross sections. A spherical optical model treatment is generally adequate to describe the cross sections in this energy region; however, in 54Fe the direct coupling is found to increase suddenly above 4 MeV and requires an increase in the DWBA deformation parameter by approximately 25%. This has little effect on the elastic scattering differential cross sections but makes a significant improvement in both the strength and shape of the inelastic scattering angular distribution, which are found to be very sensitive to the size and extent of the surface absorption region.

Dynamics of water and ions in clays of type montmorillonite by microscopic simulation and quasi-elastic neutron scattering

International Nuclear Information System (INIS)

Malikova, N.

2005-09-01

Montmorillonite clays in low hydration states, with Na + and Cs + compensating counter ions, are investigated by a combination of microscopic simulation and quasi-elastic neutron scattering to obtain information on the local structure and dynamics of water and ions in the interlayer. At first predictions of simulation into the dynamics of water and ions at elevate temperatures are shown (0 deg C 80 deg C, pertinent for the radioactive waste disposal scenario) Marked difference is observed between the modes of diffusion of the Na + and C + counter ions. In water dynamics, a significant step towards bulk water behaviour is seen on transition from the mono- to bilayer states. Secondly, a detailed comparison between simulation and quasi-elastic neutron scattering (Neutron Spin Echo and Time-of-Flight) regarding ambient temperature water dynamics is presented. Overall, the approaches are found to be in good agreement with each other and limitations of each of the methods are clearly shown. (author)

Coherent versus incoherent dynamics in InAs quantum-dot active wave guides

DEFF Research Database (Denmark)

Borri, Paola; Langbein, W.; Hvam, Jørn Märcher

2001-01-01

Coherent dynamics measured by time-resolved four-wave mixing is compared to incoherent population dynamics measured by differential transmission spectroscopy on the ground-state transition at room temperature of two types of InAs-based quantum dots with different confinement energies. The measure....... The measurements are performed with heterodyne detection on quantum-dot active wave guides to enhance the light-matter interaction length. An elastic nature of the measured dephasing is revealed which is independent of the dot energy level scheme....

Mixed quantum/classical approach to OH-stretch inelastic incoherent neutron scattering spectroscopy for ambient and supercooled liquid water and ice Ih

Energy Technology Data Exchange (ETDEWEB)

Shi, L.; Skinner, J. L. [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

2015-07-07

OH-stretch inelastic incoherent neutron scattering (IINS) has been measured to determine the vibrational density of states (VDOS) in the OH-stretch region for liquid water, supercooled water, and ice Ih, providing complementary information to IR and Raman spectroscopies about hydrogen bonding in these phases. In this work, we extend the combined electronic-structure/molecular-dynamics (ES/MD) method, originally developed by Skinner and co-workers to simulate OH-stretch IR and Raman spectra, to the calculation of IINS spectra with small k values. The agreement between theory and experiment in the limit k → 0 is reasonable, further validating the reliability of the ES/MD method in simulating OH-stretch spectroscopy in condensed phases. The connections and differences between IINS and IR spectra are analyzed to illustrate the advantages of IINS over IR in estimating the OH-stretch VDOS.

Mixed quantum/classical approach to OH-stretch inelastic incoherent neutron scattering spectroscopy for ambient and supercooled liquid water and ice Ih

International Nuclear Information System (INIS)

Shi, L.; Skinner, J. L.

2015-01-01

OH-stretch inelastic incoherent neutron scattering (IINS) has been measured to determine the vibrational density of states (VDOS) in the OH-stretch region for liquid water, supercooled water, and ice Ih, providing complementary information to IR and Raman spectroscopies about hydrogen bonding in these phases. In this work, we extend the combined electronic-structure/molecular-dynamics (ES/MD) method, originally developed by Skinner and co-workers to simulate OH-stretch IR and Raman spectra, to the calculation of IINS spectra with small k values. The agreement between theory and experiment in the limit k → 0 is reasonable, further validating the reliability of the ES/MD method in simulating OH-stretch spectroscopy in condensed phases. The connections and differences between IINS and IR spectra are analyzed to illustrate the advantages of IINS over IR in estimating the OH-stretch VDOS

Slow neutron scattering in molecular crystals. 5-4

International Nuclear Information System (INIS)

Inoue, Kazuhiko

1976-01-01

The utilization of incoherent inelastic neutron scattering (INS) as a probe for molecular crystals is reviewed. In particular, some typical examples of the measurement of incoherent inelastic neutron scattering spectra (INSS) in molecular crystals are presented in the first section of this report. The results of measurement are shown for theta-xylene, benzene, polypropylene oxide, deuteride, and formic acid. The second section presents an equation for the incoherent scattering cross section of a crystal by dividing the molecular motion into the outer and inner modes. Phonon expansion is also used for the easy understanding of the relation between the INSS and the dynamic characteristics of molecular crystals. In the third section, the measured results are analyzed on the basis of the theory presented in the previous section. And the difference between the van der Waals bond and the hydrogen bond is shortly discussed. (Aoki, K.)

A new version of PIRK (elastic pion-nucleus scattering) to handle differing proton and neutron radii

International Nuclear Information System (INIS)

Funsten, H.O.

1979-01-01

This program is a modification of the Eisenstein-Miller program (1974) for calculating elastic pion-nucleus differential cross sections using free π-N scattering amplitudes. This revision permits the use of separate proton and neutron radii for the nuclear density function rho(r). (Auth.)

Elastic neutron-proton differential cross section at 647 MeV

International Nuclear Information System (INIS)

Evans, M.L.

1979-04-01

The differential cross section for n-p elastic scattering in the angular range 51 0 was measured with high statistical accuracy using the 647 MeV monoenergetic neutron beam of the Los Alamos Meson Physics Facility. A proton recoil magnetic spectrometer was used for momentum analysis of the charge exchange protons from the reaction n+p→p+n. Absolute normalization of the cross section was established to within 7% using existing cross section data for the reaction p+p→π + +d. The results differ significantly from previous Dubna and PPA cross sections but agree well with recent Saclay data except at extreme backward angles. 41 references

Neutron Elastic Scattering Cross Sections of Iron and Zinc in the Energy Region 2.5 to 8.1 MeV

International Nuclear Information System (INIS)

Holmqvist, B.; Johansson, S.G.; Lodin, G.; Wiedling, T.; Kiss, A.

1966-12-01

Angular distributions were measured for the elastic scattering of neutrons from iron at five energies between 3.0 and 8. 1 MeV and from zinc at eight energies between 2.5 and 8.1 MeV. Time-of-flight technique was used. Corrections for neutron flux attenuation, multiple elastic scattering, and the finite geometry of the source-sample detector system were made by using a Monte Carlo program. An optical model potential with Saxon-Woods form factors was used to fit theoretical angular distributions to the experimental ones. The parameter values giving the best fits to the experimental distributions were calculated by a computer

Neutron Elastic Scattering Cross Sections of Iron and Zinc in the Energy Region 2.5 to 8.1 MeV

Energy Technology Data Exchange (ETDEWEB)

Holmqvist, B; Johansson, S G; Lodin, G; Wiedling, T [AB Atomenergi, Nyko eping (Sweden); Kiss, A [Inst. for Experimental Physics, Univ. of Debrecen, De brecen (Hungary)

1966-12-15

Angular distributions were measured for the elastic scattering of neutrons from iron at five energies between 3.0 and 8. 1 MeV and from zinc at eight energies between 2.5 and 8.1 MeV. Time-of-flight technique was used. Corrections for neutron flux attenuation, multiple elastic scattering, and the finite geometry of the source-sample detector system were made by using a Monte Carlo program. An optical model potential with Saxon-Woods form factors was used to fit theoretical angular distributions to the experimental ones. The parameter values giving the best fits to the experimental distributions were calculated by a computer.

Neutron Scattering from 36Ar and 4He Films

DEFF Research Database (Denmark)

Carneiro, K.

1977-01-01

Scale factors for neutron diffraction and neutron inelastic scattering are presented for common adsorbates, and the feasibility of experiments is discussed together with the information gained by each type of experiment. Diffraction, coherent inelastic scattering, and incoherent scattering are tr...

An elastic, low-background vertical focusing element for a doubly focusing neutron monochromator

International Nuclear Information System (INIS)

Smee, Stephen A.; Brand, Paul C.; Barry, Dwight D.; Broholm, Collin L.; Anand, Dave K.

2001-01-01

A novel, variable radius of curvature, device for the focusing of neutrons is presented. This elastic element consists of a thin variable thickness, constant width, aluminum blade to which diffracting crystals can be attached. When buckled, the blade assumes a circular focal shape, the radius of which is easily controlled by the relative displacement of supporting pivots. Precision electromechanical and optical measurements show that the slope of the buckled blade conforms to a circular arc to within 0.15 degree sign for radii in the range 900 mm< R<10 000 mm. This easily scalable, low mass mechanism is well suited for use in a focusing neutron monochromator, as the parasitic scattering typically associated with traditional lead screw and lever mechanisms is greatly reduced

Neutron-deuteron elastic scattering and breakup reactions below 20 MeV

Energy Technology Data Exchange (ETDEWEB)

Howell, C.R.; Tornow, W.; Pfuetzner, H.G.; Roberts, M.L.; Murphy, K.; Felsher, P.D.; Weisel, G.J.; Mertens, G.; Walter, R.L. (Duke Univ. and Triangle Universities Nuclear Lab., Durham, NC (USA)); Lambert, J.M.; Treado, P.A. (Physics Dept., Georgetown Univ., Washington, DC (USA)); Slaus, I. (Rudjer Boskovic Inst., Zagreb (Yugoslavia))

1991-05-01

In this paper we review the results of a series of high-accuracy measurements on the neutron-deuteron (n-d) scattering system at incident neutron energies below 20 MeV. These measurements were designed to: 1) provide data of sufficient accuracy to be used to refine the parametrization of the nucleon-nucleon force, 2) to test the reaction dynamics in the ''rigorous'' calculations of three-nucleon (3N) breakup reactions, and 3) identify 3N scattering observables that are specifically sensitive to three-nucleus forces and/or off-shell effects. At TUNL we have measured vector analyzing powers A{sub y}({theta}) for n-d elastic scattering and the breakup reaction to an accuracy better than {+-}0.005 and {+-}0.020, respectively. Recent results on items 1) and 2) will be presented. Also, results of cross-section measurements for n-d and p-d breakup will be compared to a ''rigorous'' 3N calculation. (orig.).

Neutron-deuteron elastic scattering and breakup reactions below 20 MeV

International Nuclear Information System (INIS)

Howell, C.R.; Tornow, W.; Pfuetzner, H.G.; Roberts, M.L.; Murphy, K.; Felsher, P.D.; Weisel, G.J.; Mertens, G.; Walter, R.L.; Lambert, J.M.; Treado, P.A.; Slaus, I.

1991-01-01

In this paper we review the results of a series of high-accuracy measurements on the neutron-deuteron (n-d) scattering system at incident neutron energies below 20 MeV. These measurements were designed to: 1) provide data of sufficient accuracy to be used to refine the parametrization of the nucleon-nucleon force, 2) to test the reaction dynamics in the ''rigorous'' calculations of three-nucleon (3N) breakup reactions, and 3) identify 3N scattering observables that are specifically sensitive to three-nucleus forces and/or off-shell effects. At TUNL we have measured vector analyzing powers A y (θ) for n-d elastic scattering and the breakup reaction to an accuracy better than ±0.005 and ±0.020, respectively. Recent results on items 1) and 2) will be presented. Also, results of cross-section measurements for n-d and p-d breakup will be compared to a ''rigorous'' 3N calculation. (orig.)

Probing the hydrogen equilibrium and kinetics in zeolite imidazolate frameworks via molecular dynamics and quasi-elastic neutron scattering experiments.

Science.gov (United States)

Pantatosaki, Evangelia; Jobic, Hervé; Kolokolov, Daniil I; Karmakar, Shilpi; Biniwale, Rajesh; Papadopoulos, George K

2013-01-21

The problem of simulating processes involving equilibria and dynamics of guest sorbates within zeolitic imidazolate frameworks (ZIF) by means of molecular dynamics (MD) computer experiments is of growing importance because of the promising role of ZIFs as molecular "traps" for clean energy applications. A key issue for validating such an atomistic modeling attempt is the possibility of comparing the MD results, with real experiments being able to capture analogous space and time scales to the ones pertained to the computer experiments. In the present study, this prerequisite is fulfilled through the quasi-elastic neutron scattering technique (QENS) for measuring self-diffusivity, by elaborating the incoherent scattering signal of hydrogen nuclei. QENS and MD experiments were performed in parallel to probe the hydrogen motion, for the first time in ZIF members. The predicted and measured dynamics behaviors show considerable concentration variation of the hydrogen self-diffusion coefficient in the two topologically different ZIF pore networks of this study, the ZIF-3 and ZIF-8. Modeling options such as the flexibility of the entire matrix versus a rigid framework version, the mobility of the imidazolate ligand, and the inclusion of quantum mechanical effects in the potential functions were examined in detail for the sorption thermodynamics and kinetics of hydrogen and also of deuterium, by employing MD combined with Widom averaging towards studying phase equilibria. The latter methodology ensures a rigorous and efficient way for post-processing the dynamics trajectory, thereby avoiding stochastic moves via Monte Carlo simulation, over the large number of configurational degrees of freedom a nonrigid framework encompasses.

Evaluation of dynamic elasticity module in samples of Portland (type 1) cement paste exposed to neutronic irradiation

International Nuclear Information System (INIS)

Rosa Junior, A.A.; Lucki, G.

1986-01-01

The fast neutron radiation effects and temperature on Portland cement are studied. The Dynamic Elasticity Module (Ed) in samples of Portland cement paste was evaluated. Ultrassonic technics were applied (resonance frequency and pulse velocity). The samples were irradiated with fast neutrons to fluence of 7,2 x 10 18 n/cm 2 (E approx. 1 MeV), at temperature of 120 + - 5 0 C, due to gamma heating. This temperature was simulated in laboratory in a microwave oven. (Author) [pt

Neutron Elastic Scattering Cross Sections of the Elements Ni, Co, and Cu between 1.5 and 8.0 MeV

Energy Technology Data Exchange (ETDEWEB)

Holmqvist, B; Wiedling, T

1967-12-15

Angular distributions of elastically scattered neutrons have been measured for natural nickel at seven energies between 3.0 and 8.1 MeV and for cobalt and copper at ten energies between 1.5 and 8.1 MeV, by using time-of-flight technique. The observed angular distributions were corrected for neutron flux attenuation, multiple elastic scattering, and the finite geometry of the source-sample-detector system by using a Monte Carlo computer program. Theoretical angular distributions have been fitted to the experimental angular distributions by using an optical model potential with Saxon-Woods form factors. A computer program was used to find parameter values of the potential giving the best fittings to the experimental angular distributions.

Differential cross sections for carbon neutron elastic and inelastic scattering from 8.0 to 14.5 MeV

Energy Technology Data Exchange (ETDEWEB)

Haouat, G.; Lachkar, J.; Patin, Y.; Sigaud, J.; Cocu, F.

1975-06-01

Differential elastic and inelastic cross sections for fast neutrons scattered by carbon have been measured between 8.0 and 14.5 MeV. No experimental results on {sup 12}C seem to have been reported, at this time, between 9 and 14 MeV. A complete and consistent set of data on carbon, including total, elastic and inelastic, (n,α) and (n,n'3α) cross sections, is now available for energies below 14.5MeV.

Mode coupling analysis of coherent quasi-elastic neutron scattering from fluorite-type materials approaching the superionic transition

International Nuclear Information System (INIS)

Chaturvedi, D.K.; Tosi, M.P.

1987-08-01

Neutron scattering experiments on SrCl 2 , CaF 2 and PbF 2 have shown that intensity and width of the coherent diffuse quasi-elastic spectrum increase rapidly with temperature into the fast-ion conducting phase, the main feature in the integrated quasi-elastic intensity being a peak just beyond the (200) point along the (100) direction in scattering wave vector space. The Zwanzig-Mori memory function formalism is used in this work to analyze the quasi-elastic scattering cross section from charge density fluctuations in terms of anharmonic couplings between the vibrational modes of the crystal. The two- and three-mode channels are examined for compatibility with the quasi-elastic neutron scattering evidence, on the basis of (i) energy and momentum conservation and van Hove singularity arguments and (ii) measured phonon dispersion curves along the main symmetry directions in SrCl 2 , CaF 2 , SrF 2 and BaF 2 . The analysis identifies a specific microscopic role for the Raman-active optic branches. The eigenvectors of the relevant Raman-active and partner modes in the three-mode channel describe relative displacements of the two halogens in the unit cell superposed on relative displacements of the halogen and alkaline earth components. This microscopic picture is thus consistent with the superionic transition being associated with the onset of dynamic disorder in the anionic component of the crystal. (author). 13 refs, 2 tabs

Release of Continuous Representation for S(α,β) ACE Data

Energy Technology Data Exchange (ETDEWEB)

Conlin, Jeremy Lloyd [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parsons, Donald Kent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-03-20

For low energy neutrons, the default free gas model for scattering cross sections is not always appropriate. Molecular effects or crystalline structure effects can affect the neutron scattering cross sections. These effects are included in the S(α; β) thermal neutron scattering data and are tabulated in file 7 of the ENDF6 format files. S stands for scattering. α is a momentum transfer variable and is an energy transfer variable. The S(α; β) cross sections can include coherent elastic scattering (no E change for the neutron, but specific scattering angles), incoherent elastic scattering (no E change for the neutron, but continuous scattering angles), and inelastic scattering (E change for the neutron, and change in angle as well). Every S(α; β) material will have inelastic scattering and may have either coherent or incoherent elastic scattering (but not both). Coherent elastic scattering cross sections have distinctive jagged-looking Bragg edges, whereas the other cross sections are much smoother. The evaluated files from the NNDC are processed locally in the THERMR module of NJOY. Data can be produced either for continuous energy Monte Carlo codes (using ACER) or embedded in multi-group cross sections for deterministic (or even multi-group Monte Carlo) codes (using GROUPR). Currently, the S(α; β) files available for MCNP use discrete energy changes for inelastic scattering. That is, the scattered neutrons can only be emitted at specific energies— rather than across a continuous spectrum of energies. The discrete energies are chosen to preserve the average secondary neutron energy, i.e., in an integral sense, but the discrete treatment does not preserve any differential quantities in energy or angle.

Study of ammonium molecular ion impurity modes in Rb1-x(NH4)xI mixed crystals by inelastic incoherent neutron scattering

International Nuclear Information System (INIS)

Smirnov, L.S.; Natkaniec, I.; Ollivier, J.; Dianoux, J.A.; Martinez Sarrion, M.L.; Mestres, L.

2010-01-01

The study of ammonium dynamics in Rb 1-x (NH 4 ) x I mixed crystals was carried out by inelastic incoherent neutron scattering in the concentration region of orientationally disordered α-phase, 0.0< x<0.40, at the temperature range from 2 to 150 K. The observed resonance modes correspond to three energy regions: 0.19-0.481 (I), 0.56-3.0 (II) and 4.0-10.0 (III) meV. The modes of region I could be described by rotational tunneling energies of the multipole moments of ammonium ions. The modes within energy region II correspond to the calculated rotational tunneling energies between splitted levels of the ground librational level of ammonium ion. The modes of region III can be described as local gap modes of ammonium ion because they are located between acoustic and optic branches of RbI phonon density of states

Protein dynamics by neutron scattering: The protein dynamical transition and the fragile-to-strong dynamical crossover in hydrated lysozyme

International Nuclear Information System (INIS)

Magazù, Salvatore; Migliardo, Federica; Benedetto, Antonio; Vertessy, Beata

2013-01-01

Highlights: • The role played by the instrumental energy resolution in neutron scattering is presented. • The effect of natural bioprotectants on protein dynamics is shown. • A connection between the protein dynamical transition and the fragile-to-strong dynamical crossover is formulated. - Abstract: In this work Elastic Incoherent Neutron Scattering (EINS) results on lysozyme water mixtures in absence and in presence of bioprotectant systems are presented. The EINS data have been collected by using the IN13 and the IN10 spectrometers at the Institut Laue-Langevin (ILL, Grenoble, France) allowing to evaluate the temperature behaviour of the mean square displacement and of the relaxation time for the investigated systems. The obtained experimental findings together with theoretical calculations allow to put into evidence the role played by the spectrometer resolution and to clarify the connexion between the registered protein dynamical transition, the system relaxation time, and the instrumental energy resolution

Study of the diffusion movements of water by quasi-elastic scattering of slow neutrons

International Nuclear Information System (INIS)

Yamazaki, Ione Makiko

1980-01-01

The diffusion movements of water at three different temperatures in the liquid state have been studied by slow neutron quasi-elastic scattering. The measurements have been performed using the IPEN Triple Axis Spectrometer. Broadening and integrated intensity of the quasi-elastic line have been determined for several momentum transfer (K) in the range 0,7627 ≤ K ≤ 2,993 A -1 . The broadening of the quasi-elastic peaks as function of momentum transfer (K) observed at various temperatures has been interpreted in terms of globular diffusion models. The results obtained at 30 deg C have been explained in a consistent way considering the translational and rotational globular diffusion movements. To describe the results obtained at 55 deg and 70 deg C only the translational globular diffusion model was sufficient. This analysis indicates the existence in water of globules with distance of the farest proton position to the center of gravity of the globule 4,5 A, corroborating the idea of quasi-crystalline structure for water. The Debye-Waller factor has been obtained through the analysis of the integrated intensity of quasi-elastic scattering peaks over the K 2 measured range. From this analysis an estimative of the mean square displacement was obtained. (author)

SASSI, Total and Differential Elastic and Inelastic Neutron Cross-Sections by Hauser-Feshbach

International Nuclear Information System (INIS)

Benzi, V.; Fabbri, F.; Zuffi, L.

2001-01-01

1 - Nature of physical problem solved: Neutron total and differential elastic and inelastic cross-section evaluation by means of the statistical model of Hauser-Feshbach (1) as modified by D. Goldman (2) (3). The Goldman modification includes the effect of spin-orbit coupling on transmission coefficients. 2 - Method of solution: For numerical integration the Fox-Goodwins method is used. 3 - Restrictions on the complexity of the problem: Angular momentum I less than or equal to 50. Number of excited levels less than or equal to 30

Present needs and future trends in neutron crystallography and spectroscopy

International Nuclear Information System (INIS)

Williams, J.M.

1978-11-01

Topics covered include: structural investigation by neutron and x-ray diffraction; sources and characteristics of neutron radiation; time-of-flight techniques; overview of neutron crystallography and structural chemistry; hydrogen bonds; transition-metal hydride complexes; actinide and lanthanide complexes; carbon-hydrogen-metal interactions in organometallic chemistry and catalysis; metal clusters and catalysis; materials with unusual solid-state properties; biochemical molecules and biological systems; electron and spin density distributions in crystalline solids; incoherent neutron-scattering spectroscopy; and quasielastic neutron scattering and high resolution spectroscopy

Neutron-scattering study of low-energy excitations in triphenyl phosphite

CERN Document Server

Mayer, J; Massalska-Arodz, M; Janik, J A; Natkaniec, I; Steinsvoll, O

2002-01-01

The low-energy excitations in crystalline and glassy triphenyl phosphite were studied by inelastic incoherent neutron scattering with two different instruments. The results - the incoherent dynamic structure factor S(2 theta,omega) and the density of states G(omega) - were obtained using direct and inverted geometry time-of-flight spectrometers, respectively. The probable origin of the excess density of states in the glass (boson peak) is discussed. (orig.)

Neutron-scattering study of low-energy excitations in triphenyl phosphite

International Nuclear Information System (INIS)

Mayer, J.; Krawczyk, J.; Massalska-Arodz, M.; Janik, J.A.; Natkaniec, I.; Steinsvoll, O.

2002-01-01

The low-energy excitations in crystalline and glassy triphenyl phosphite were studied by inelastic incoherent neutron scattering with two different instruments. The results - the incoherent dynamic structure factor S(2θ,ω) and the density of states G(ω) - were obtained using direct and inverted geometry time-of-flight spectrometers, respectively. The probable origin of the excess density of states in the glass (boson peak) is discussed. (orig.)

Atomic-resolution neutron holography

International Nuclear Information System (INIS)

Cser, L.; Toeroek, Gy.; Krexner, G.

2001-01-01

Atomic-resolution neutron holography can be realised by two different schemes. In the frame of the first approach a point-like source of slow neutrons is produced inside the investigated crystal. Due to the extremely large value of the incoherent-scattering cross-section of the proton, hydrogen atoms imbedded in a metal single-crystal lattice may serve as point-like sources when the sample is irradiated by a monochromatic beam of slow neutrons. The second approach utilizes the registration of the interference between the incident and scattered waves by means of a point-like detector inserted in the lattice of the crystal under investigation. In addition, neutron-induced electron holography is considered. The feasibility of these ideas is discussed. (orig.)

Determination of the fast neutrons spectra by the Elastic scattering method (n, p); Determinacion del espectro de neutrones rapidos por el metodo de la dispersion elastica (n, p)

Energy Technology Data Exchange (ETDEWEB)

Elizalde D, J

1973-07-01

This work consists in determining the fast neutron spectra emitted by a Pu-Be isotopic source. The implemented technique is based in the spectrometry (n, p). This consists in making to fall on a fast neutrons beams (polyenergetic) over a thin film of hydrogenated material, detecting the spectra of emitted protons at a fix angle. The polyethylene film and the used solid state detector are inside of a vacuum chamber. The detector is placed at 30 degree with respect to direction of the incident neutrons beam. The protons spectra is stored in a multichannel. the energy is obtained with the prior calibration of the system. The data processing involves the transformation of the protons spectra observed at the falling on neutrons spectra over the film. The energy of the neutrons is related with that of the protons, according to the collision kinematical equations. The cross section of elastic collision of the neutrons with the hydrogen atoms is obtained from literature. Applying these relations to the observed spectra it is obtained the falling on neutron spectra over the film. (Author)

On elastic moduli and elastic anisotropy in polycrystalline martensitic NiTi

International Nuclear Information System (INIS)

Qiu, S.; Clausen, B.; Padula, S.A.; Noebe, R.D.; Vaidyanathan, R.

2011-01-01

A combined experimental and computational effort was undertaken to provide insight into the elastic response of B19' martensitic NiTi variants as they exist in bulk, polycrystalline aggregate form during monotonic tensile and compressive loading. The experimental effort centered on using in situ neutron diffraction during loading to measure elastic moduli in several directions along with an average Young's modulus and a Poisson's ratio. The measurements were compared with predictions from a 30,000 variant, self-consistent polycrystalline deformation model that accounted for the elastic intergranular constraint, and also with predictions of single crystal behavior from previously published ab initio studies. Variant conversion and detwinning processes that influenced the intergranular constraint occurred even at stresses where the macroscopic stress-strain response appeared linear. Direct evidence of these processes was revealed in changes in texture, which were captured in inverse pole figures constructed from the neutron diffraction measurements.

Methyl group rotation and segmental motion in atactic polypropylene. An incoherent quasi elastic neutron scattering investigation

International Nuclear Information System (INIS)

Arrighi, V.; Triolo, A.

1999-01-01

Complete text of publication follows. Results from the analysis of recent quasielastic neutron scattering (QENS) experiments on atactic polypropylene (aPP), are presented both in the sub-T g and above T g regimes. Experiments were carried out on the IRIS (ISIS, Rutherford Appleton Laboratory, UK) and IN10 (ILL FR) spectrometers in the temperature range from 140 to 400 K. Different instrumental resolutions were used in order to cover a wide energy window. The high resolution data collected on IN10 using the fixed energy scan technique, give clear evidence of two separate dynamic processes that we attribute to methyl group rotational hopping (below T g ) and to segmental motion (above T g ), respectively. Data were fitted using a model involving a distribution of relaxation rates. The IN10 results are used in interpreting and analyzing the QENS data from the IRIS spectrometer. In order to exploit the different energy resolutions of IRIS, Fourier inversion of the experimental data was carried out. This approach to data analysis allows us to widen the energy range available for data analysis. Due to the high activation energy of the methyl group hopping in aPP, this motion overlaps with the segmental relaxation, thus making analysis of high temperature data quite complex. The IN10 results are employed in order to perform data analysis in terms of two distinct processes. (author)

Spectral long-range interaction of temporal incoherent solitons.

Science.gov (United States)

Xu, Gang; Garnier, Josselin; Picozzi, Antonio

2014-02-01

We study the interaction of temporal incoherent solitons sustained by a highly noninstantaneous (Raman-like) nonlinear response. The incoherent solitons exhibit a nonmutual interaction, which can be either attractive or repulsive depending on their relative initial distance. The analysis reveals that incoherent solitons exhibit a long-range interaction in frequency space, which is in contrast with the expected spectral short-range interaction described by the usual approach based on the Raman-like spectral gain curve. Both phenomena of anomalous interaction and spectral long-range behavior of incoherent solitons are described in detail by a long-range Vlasov equation.

Comparisons of vector analyzing-power data and calculations for neutron-deuteron elastic scattering from 10 to 14 MeV

International Nuclear Information System (INIS)

Howell, C.R.; Tornow, W.; Murphy, K.; Pfuetzner, H.G.; Roberts, M.L.; Li, A.; Felsher, P.D.; Walter, R.L.; Slaus, I.; Treado, P.A.; Koike, Y.

1987-01-01

High-accuracy analyzing-power A y (θ) data for n-d elastic scattering at 12 MeV have been measured using the polarized-neutron facilities at the Triangle Universities Nuclear Laboratory (TUNL). The present data have been combined with previous n-d measurements at 10, 12, and 14.1 MeV to form the highest-accuracy A y (θ) data set for n-d elastic scattering below 20 MeV. These data are compared to recent Faddeev-based neutron-deuteron (n-d) calculations which use the Paris and Bonn equivalent separable potentials PEST and BEST, as well as Doleschall's representation of the P- and D-wave nucleon-nucleon interactions. None of these models adequately describe the data in the angular region around the maximum of A y (θ). Possible reasons for the discrepancies are discussed. The sensitivity of the present Faddeev-based calculations to various angular momentum components of the nucleon-nucleon interaction are examined. (Auth.)

A new apparatus design for high temperature (up to 950°C) quasi-elastic neutron scattering in a controlled gaseous environment.

Science.gov (United States)

al-Wahish, Amal; Armitage, D; al-Binni, U; Hill, B; Mills, R; Jalarvo, N; Santodonato, L; Herwig, K W; Mandrus, D

2015-09-01

A design for a sample cell system suitable for high temperature Quasi-Elastic Neutron Scattering (QENS) experiments is presented. The apparatus was developed at the Spallation Neutron Source in Oak Ridge National Lab where it is currently in use. The design provides a special sample cell environment under controlled humid or dry gas flow over a wide range of temperature up to 950 °C. Using such a cell, chemical, dynamical, and physical changes can be studied in situ under various operating conditions. While the cell combined with portable automated gas environment system is especially useful for in situ studies of microscopic dynamics under operational conditions that are similar to those of solid oxide fuel cells, it can additionally be used to study a wide variety of materials, such as high temperature proton conductors. The cell can also be used in many different neutron experiments when a suitable sample holder material is selected. The sample cell system has recently been used to reveal fast dynamic processes in quasi-elastic neutron scattering experiments, which standard probes (such as electrochemical impedance spectroscopy) could not detect. In this work, we outline the design of the sample cell system and present results demonstrating its abilities in high temperature QENS experiments.

Modeling Incoherent Electron Cloud Effects

International Nuclear Information System (INIS)

Vay, Jean-Luc; Benedetto, E.; Fischer, W.; Franchetti, G.; Ohmi, K.; Schulte, D.; Sonnad, K.; Tomas, R.; Vay, J.-L.; Zimmermann, F.; Rumolo, G.; Pivi, M.; Raubenheimer, T.

2007-01-01

Incoherent electron effects could seriously limit the beam lifetime in proton or ion storage rings, such as LHC, SPS, or RHIC, or blow up the vertical emittance of positron beams, e.g., at the B factories or in linear-collider damping rings. Different approaches to modeling these effects each have their own merits and drawbacks. We describe several simulation codes which simplify the descriptions of the beam-electron interaction and of the accelerator structure in various different ways, and present results for a toy model of the SPS. In addition, we present evidence that for positron beams the interplay of incoherent electron-cloud effects and synchrotron radiation can lead to a significant increase in vertical equilibrium emittance. The magnitude of a few incoherent e+e- scattering processes is also estimated. Options for future code development are reviewed

Possible Moessbauer or neutron experiments on fluid interfaces and on smectics

International Nuclear Information System (INIS)

Gennes, P.G. de

1975-01-01

The spectrum of γ rays emitted from an atom bound to the free surface of a fluid is expected to show a low frequency anomaly associated with the two dimensional character of the capillary waves. This is discussed here a) for liquid metals, where initial effects should be dominant, b) for viscous fluids, c) for thin films (100A) of a liquid above a solid surface. If the anomaly turns out to be visible, it could give some informations on dissipative effects in monomolecular layers at frequencies of the order 10 8 -10 9 cycles. The theoretical emission spectrum from a smectic A liquid crystal is also considered. Finally, some remarks are presented concerning the incoherent, quasi elastic scattering of neutrons by smectics with a scattering vector normal to the layers: the same anomalies are expected and could possibly be seen with present high resolution spectrometers [fr

Dynamics of proteins and of their hydration layer studied by neutron scattering and additional biophysical methods

International Nuclear Information System (INIS)

Gallat, Francois-Xavier

2011-01-01

This thesis work focused on the dynamics of proteins, surrounded by their hydration layer, a water shell around the protein vital for its biological function. Each of these components is accompanied by a specific dynamics which union reforms the complex energy landscape of the system. The joint implementation of selective deuteration, incoherent neutron scattering and tera-hertz spectroscopy allowed to explore the dynamics of proteins and that of the hydration shell. The influence of the folding state of protein on its dynamics has been studied by elastic neutron scattering. Globular proteins were less dynamic than its intrinsically disordered analogues. Themselves appear to be stiffer than non-physiological unfolded proteins. The oligomerization state and the consequences on the dynamics were investigated. Aggregates of a globular protein proved to be more flexible than the soluble form. In contrast, aggregates of a disordered protein showed lower average dynamics compared to the soluble form. These observations demonstrate the wide range of dynamics among the proteome. Incoherent neutron scattering experiences on the hydration layer of globular and disordered proteins have yielded information on the nature of water motion around these proteins. The measurements revealed the presence of translational motions concomitant with the onset of the transition dynamics of hydration layers, at 220 K. Measurements have also shown a stronger coupling between a disordered protein and its hydration water, compared to a globular protein and its hydration shell. The nature of the hydration layer and its influence on its dynamics has been explored with the use of polymers that mimic the water behavior and that act as a source of flexibility for the protein. Eventually, the dynamics of methyl groups involved in the dynamical changes observed at 150 and 220 K, was investigated. (author) [fr

Static and quasi-elastic small angle neutron scattering on biocompatible ionic ferrofluids: magnetic and hydrodynamic interactions

CERN Document Server

Gazeau, F; Dubois, E; Perzynski, R

2003-01-01

We investigate the structure and dynamics of ionic magnetic fluids (MFs), based on ferrite nanoparticles, dispersed at pH approx 7 either in H sub 2 O or in D sub 2 O. Polarized and non-polarized static small angle neutron scattering (SANS) experiments in zero magnetic field allow us to study both the magnetic and the nuclear contributions to the neutron scattering. The magnetic interparticle attraction is probed separately from the global thermodynamic repulsion and compares well to direct magnetic susceptibility measurements. The magnetic interparticle correlation is in these fluid samples independent of the probed spatial scale. In contrast, a spatial dependence of the interparticle correlation is evidenced at large PHI by the nuclear structure factor. A model of magnetic interaction quantitatively explains the under-field anisotropy of the SANS nuclear contribution. In a quasi-elastic neutron spin-echo experiment, we probe the Brownian dynamics of translation of the nanoparticles in the range 1.3 sup<=...

On elastic moduli and elastic anisotropy in polycrystalline martensitic NiTi

Energy Technology Data Exchange (ETDEWEB)

Qiu, S. [Advanced Materials Processing and Analysis Center (AMPAC), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, FL 32816 (United States); Clausen, B. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Padula, S.A.; Noebe, R.D. [NASA Glenn Research Center, Cleveland, OH 44135 (United States); Vaidyanathan, R., E-mail: raj@mail.ucf.edu [Advanced Materials Processing and Analysis Center (AMPAC), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, FL 32816 (United States)

2011-08-15

A combined experimental and computational effort was undertaken to provide insight into the elastic response of B19' martensitic NiTi variants as they exist in bulk, polycrystalline aggregate form during monotonic tensile and compressive loading. The experimental effort centered on using in situ neutron diffraction during loading to measure elastic moduli in several directions along with an average Young's modulus and a Poisson's ratio. The measurements were compared with predictions from a 30,000 variant, self-consistent polycrystalline deformation model that accounted for the elastic intergranular constraint, and also with predictions of single crystal behavior from previously published ab initio studies. Variant conversion and detwinning processes that influenced the intergranular constraint occurred even at stresses where the macroscopic stress-strain response appeared linear. Direct evidence of these processes was revealed in changes in texture, which were captured in inverse pole figures constructed from the neutron diffraction measurements.

Phase-shift-analysis approach to elastic neutron scattering from 12C between 9 and 12 MeV

International Nuclear Information System (INIS)

Tornow, W.

1985-01-01

The excitation energy, spin and parity of levels in 13 C have been determined for excitation energies between 13 and 16 MeV via a phase-shift analysis of the measured total cross section, elastic differential cross section and analysing power for n + 12 C in the neutron energy range from 8.9 to 12.0 MeV. New analysing power measurements are reported for this energy range. The present and previous experimental data are well described by the phase shifts obtained. The non-elastic cross section for n + 12 C predicted from the phase shifts is in good agreement with the ENDF/B-V evaluation. The need for further experimental data is pointed out. (author)

Molecular mobility in Medicago truncatula seed during early stage of germination: Neutron scattering and NMR investigations

Energy Technology Data Exchange (ETDEWEB)

Falourd, Xavier [UR1268 Biopolymères Interactions Assemblages, INRA, F-44316 Nantes (France); Natali, Francesca [CNR-IOM-OGG, c/o Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Peters, Judith [Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France); Université Joseph Fourier UFR PhITEM, BP 53, 38041 Grenoble Cedex 9 (France); Institut de Biologie Structurale, 41 rue Jules Horowitz, 38027 Grenoble Cedex 1 (France); Foucat, Loïc, E-mail: Loic.Foucat@nantes.inra.fr [UR1268 Biopolymères Interactions Assemblages, INRA, F-44316 Nantes (France)

2014-01-15

Highlights: • Neutron scattering and NMR approaches were used to characterize seed germination. • A parallel between macromolecular motions and water dynamics was established. • Freezing/thawing cycle revealed a hysteresis connected to the seed hydration level. - Abstract: First hours of Medicago truncatula (MT) seeds germination were investigated using elastic incoherent neutron scattering (EINS) and nuclear magnetic resonance (NMR), to follow respectively how macromolecular motions and water mobility evolve when water permeates into the seed. From EINS results, it was shown that there is an increase in macromolecular mobility with the water uptake. Changes in NMR relaxation parameters reflected microstructural changes associated with the recovery of the metabolic processes. The EINS investigation of the effect of temperature on macromolecular motions showed that there is a relationship between the amount of water in the seeds and the effect of freezing–thawing cycle. The NMR relaxometry results obtained at 253 K allowed establishing possible link between the freezing of water molecules tightly bound to macromolecules and their drastic motion restriction around 250 K, as observed with EINS at the highest water content.

The determination of the elastic properties of an anisotropic polycrystalline graphite using neutron diffraction and ultrasonic measurements

Czech Academy of Sciences Publication Activity Database

Lokajíček, Tomáš; Lukáš, Petr; Nikitin, A. N.; Papushkin, I.V.; Sumin, V. V.; Vasin, R.N.

2010-01-01

Roč. 49, č. 4 (2010), s. 1374-1384 ISSN 0008-6223 R&D Projects: GA ČR GA205/08/0676 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z10480505 Keywords : extruded graphite * elastic properties * neutron diffraction * ultrasonic sounding * thermal-expansion * self-consistent * young moduls * porosity * stress * rocks Subject RIV: DB - Geology ; Mineralogy Impact factor: 4.893, year: 2010

Photoproduction of Inelastic and Elastic $J/\\psi$ Vector Mesons

Energy Technology Data Exchange (ETDEWEB)

Stundzia, Audrius Bronius [Toronto U.

1992-06-01

Results and analysis on the inelastic and elastic photoproduction of $J /\\psi$ vector mesons by Fermilab experiment E691 are presented. The inelastic, deep inelastic, coherent elastic and incoherent elastic cross sections were measured at ($E_{\\gamma}$) = 145 GeV. The $d\\sigma / dzdp^2_{\\tau}$} distribution and the photon energy dependence of the cross sections for these production processes were also measured. The deep inelastic $J /\\psi$ was analyzed in the colour-singlet photon-gluon-fusion model. It was found that the $d\\sigma / dzdp^2_{\\tau}$ distribution and the the rise of the cross section with $E\\gamma$ are both well described by a relatively soft gluon distribution [xG( x) $\\alpha$ ($1 - x )^{ng}$, where $n_g$ = 6.5 ± 1.1 (stat.)$^{+1.0}_{-0.6}$(syst.)].

A Unified approach for nucleon knock-out, coherent and incoherent pion production in neutrino interactions with nuclei

CERN Document Server

Martini, M.; Chanfray, G.; Marteau, J.

2009-01-01

We present a theory of neutrino interactions with nuclei aimed at the description of the partial cross-sections, namely quasi-elastic and multi-nucleon emission, coherent and incoherent single pion production. For this purpose, we use the theory of nuclear responses treated in the random phase approximation, which allows a unified description of these channels. It is particularly suited for the coherent pion production where collective effects are important whereas they are moderate in the other channels. We also study the evolution of the neutrino cross-sections with the mass number from carbon to calcium. We compare our approach to the available neutrino experimental data on carbon. We put a particular emphasis on the multi-nucleon channel, which at present is not easily distinguishable from the quasi-elastic events. This component turns out to be quite relevant for the interpretation of experiments (K2K, MiniBooNE, SciBooNE). It can account in particular for the unexpected behavior of the quasi-elastic cro...

Diffuse scattering of neutrons

International Nuclear Information System (INIS)

Novion, C.H. de.

1981-02-01

The use of neutron scattering to study atomic disorder in metals and alloys is described. The diffuse elastic scattering of neutrons by a perfect crystal lattice leads to a diffraction spectrum with only Bragg spreads. the existence of disorder in the crystal results in intensity and position modifications to these spreads, and above all, to the appearance of a low intensity scatter between Bragg peaks. The elastic scattering of neutrons is treated in this text, i.e. by measuring the number of scattered neutrons having the same energy as the incident neutrons. Such measurements yield information on the static disorder in the crystal and time average fluctuations in composition and atomic displacements [fr

A new apparatus design for high temperature (up to 950 °C) quasi-elastic neutron scattering in a controlled gaseous environment

International Nuclear Information System (INIS)

Al-Wahish, Amal; Armitage, D.; Hill, B.; Mills, R.; Santodonato, L.; Herwig, K. W.; Al-Binni, U.; Jalarvo, N.; Mandrus, D.

2015-01-01

A design for a sample cell system suitable for high temperature Quasi-Elastic Neutron Scattering (QENS) experiments is presented. The apparatus was developed at the Spallation Neutron Source in Oak Ridge National Lab where it is currently in use. The design provides a special sample cell environment under controlled humid or dry gas flow over a wide range of temperature up to 950 °C. Using such a cell, chemical, dynamical, and physical changes can be studied in situ under various operating conditions. While the cell combined with portable automated gas environment system is especially useful for in situ studies of microscopic dynamics under operational conditions that are similar to those of solid oxide fuel cells, it can additionally be used to study a wide variety of materials, such as high temperature proton conductors. The cell can also be used in many different neutron experiments when a suitable sample holder material is selected. The sample cell system has recently been used to reveal fast dynamic processes in quasi-elastic neutron scattering experiments, which standard probes (such as electrochemical impedance spectroscopy) could not detect. In this work, we outline the design of the sample cell system and present results demonstrating its abilities in high temperature QENS experiments

Search for the first-order liquid-to-liquid phase transition in low-temperature confined water by neutron scattering

Science.gov (United States)

Chen, Sow-Hsin; Wang, Zhe; Kolesnikov, Alexander I.; Zhang, Yang; Liu, Kao-Hsiang

2013-02-01

It has been conjectured that a 1st order liquid-to-liquid (L-L) phase transition (LLPT) between high density liquid (HDL) and low density liquid (LDL) in supercooled water may exist, as a thermodynamic extension to the liquid phase of the 1st order transition established between the two bulk solid phases of amorphous ice, the high density amorphous ice (HDA) and the low density amorphous ice (LDA). In this paper, we first recall our previous attempts to establish the existence of the 1st order L-L phase transition through the use of two neutron scattering techniques: a constant Q elastic diffraction study of isobaric temperature scan of the D2O density, namely, the equation of state (EOS) measurements. A pronounced density hysteresis phenomenon in the temperature scan of the density above P = 1500 bar is observed which gives a plausible evidence of crossing the 1st order L-L phase transition line above this pressure; an incoherent quasi-elastic scattering measurements of temperature-dependence of the α-relaxation time of H2O at a series of pressures, namely, the study of the Fragile-to-Strong dynamic crossover (FSC) phenomenon as a function of pressure which we interpreted as the results of crossing the Widom line in the one-phase region. In this new experiment, we used incoherent inelastic neutron scattering (INS) to measure the density of states (DOS) of H atoms in H2O molecules in confined water as function of temperature and pressure, through which we may be able to follow the emergence of the LDL and HDL phases at supercooled temperature and high pressures. We here report for the first time the differences of librational and translational DOSs between the hypothetical HDL and LDL phases, which are similar to the corresponding differences between the well-established HDA and LDA ices. This is plausible evidence that the HDL and LDL phases are the thermodynamic extensions of the corresponding amorphous solid water HDA and LDA ices.

Neutron scattering investigations of the properties of the x - T phase diagram of Rb1-x(NH4)xI mixed crystals

International Nuclear Information System (INIS)

Smirnov, L.S.; Natkaniec, I.; Savenko, B.N.

2002-01-01

The x - T phase diagram of Rb 1-x (NH 4 ) x I is studied using samples with the ammonium concentration 0.01< x<0.77 over a wide temperature region of 15 to 300 K by neutron powder diffraction and inelastic incoherent neutron scattering. The results of powder diffraction studies show that at low temperatures a phase transition from α-phase to β-phase is observed at ammonium concentrations x = 0.50 and x = 0.66. Inelastic incoherent neutron scattering detects a region of the orientional glass state at ammonium concentrations 0.29< x,0.40

Scattering with polarized neutrons

International Nuclear Information System (INIS)

Schweizer, J.

2007-01-01

In the history of neutron scattering, it was shown very soon that the use of polarized neutron beams brings much more information than usual scattering with unpolarized neutrons. We shall develop here the different scattering methods that imply polarized neutrons: 1) polarized beams without polarization analysis, the flipping ratio method; 2) polarized beams with a uniaxial polarization analysis; 3) polarized beams with a spherical polarization analysis. For all these scattering methods, we shall give examples of the physical problems which can been solved by these methods, particularly in the field of magnetism: investigation of complex magnetic structures, investigation of spin or magnetization densities in metals, insulators and molecular compounds, separation of magnetic and nuclear scattering, investigation of magnetic properties of liquids and amorphous materials and even, for non magnetic material, separation between coherent and incoherent scattering. (author)

Neutron scattering studies on protein dynamics using the human myelin peripheral membrane protein P2

Directory of Open Access Journals (Sweden)

Laulumaa Saara

2015-01-01

Full Text Available Myelin is a multilayered proteolipid membrane structure surrounding selected axons in the vertebrate nervous system, which allows the rapid saltatory conduction of nerve impulses. Deficits in myelin formation and maintenance may lead to chronic neurological disease. P2 is an abundant myelin protein from peripheral nerves, binding between two apposing lipid bilayers. We studied the dynamics of the human myelin protein P2 and its mutated P38G variant in hydrated powders using elastic incoherent neutron scattering. The local harmonic vibrations at low temperatures were very similar for both samples, but the mutant protein had increased flexibility and softness close to physiological temperatures. The results indicate that a drastic mutation of proline to glycine at a functional site can affect protein dynamics, and in the case of P2, they may explain functional differences between the two proteins.

Neutron scattering studies on protein dynamics using the human myelin peripheral membrane protein P2

Science.gov (United States)

Laulumaa, Saara; Kursula, Petri; Natali, Francesca

2015-01-01

Myelin is a multilayered proteolipid membrane structure surrounding selected axons in the vertebrate nervous system, which allows the rapid saltatory conduction of nerve impulses. Deficits in myelin formation and maintenance may lead to chronic neurological disease. P2 is an abundant myelin protein from peripheral nerves, binding between two apposing lipid bilayers. We studied the dynamics of the human myelin protein P2 and its mutated P38G variant in hydrated powders using elastic incoherent neutron scattering. The local harmonic vibrations at low temperatures were very similar for both samples, but the mutant protein had increased flexibility and softness close to physiological temperatures. The results indicate that a drastic mutation of proline to glycine at a functional site can affect protein dynamics, and in the case of P2, they may explain functional differences between the two proteins.

Neutron scattering. Lectures

Energy Technology Data Exchange (ETDEWEB)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

2010-07-01

The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

Neutron scattering. Lectures

International Nuclear Information System (INIS)

Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner

2010-01-01

The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

Phase-shift-analysis approach to elastic neutron scattering from /sup 12/C between 9 and 12 MeV

Energy Technology Data Exchange (ETDEWEB)

Tornow, W. (Tuebingen Univ. (Germany, F.R.). Physikalisches Inst.); Walter, R.L.; Byrd, R.C. (Duke Univ., Durham, NC (USA). Dept. of Physics; Triangle Universities Nuclear Lab., Durham, NC (USA))

1985-03-01

The excitation energy, spin and parity of levels in /sup 13/C have been determined for excitation energies between 13 and 16 MeV via a phase-shift analysis of the measured total cross section, elastic differential cross section and analysing power for n + /sup 12/C in the neutron energy range from 8.9 to 12.0 MeV. New analysing power measurements are reported for this energy range. The present and previous experimental data are well described by the phase shifts obtained. The non-elastic cross section for n + /sup 12/C predicted from the phase shifts is in good agreement with the ENDF/B-V evaluation. The need for further experimental data is pointed out.

Neutron quasi-elastic scattering study of translational motions in the smectic H, C and A phases of TBBA

International Nuclear Information System (INIS)

Dianoux, A.J.; Volino, F.; Heidemann, A.; Hervet, H.

1975-01-01

Neutron quasi-elastic scattering experiments in the smectic H, C and A phases of TBBA are presented, using the high resolution backscattering technique. The data are analyzed in terms of translational motion and are characterized by an apparent self diffusion coefficient Dsub(ap). The physical meaning of Dsub(ap) is discussed in terms of the true bulk self diffusion tensor and other kinds of translational motions [fr

Some practical results for calculating the elastic properties of cubic polycrystals with texture measured by neutron diffraction

International Nuclear Information System (INIS)

Lychagina, T.A.; Brokmeier, H.G.

1999-01-01

Complete text of publication follows. It is well known that the elastic properties of a polycrystalline material are strongly dependent on the one hand the single crystal elastic properties and on the other hand its crystallographic texture [1]. The calculation of these properties needs the quantitative texture given by the orientation distribution function (ODF), which represents texture mathematically. By a given set of experimental pole figures a number of programs are available to calculate the ODF, which might have an influence on the resulting properties. The aim of this work is to compare elastic properties of cubic materials calculated with ODFs obtained by different methods. The calculations were carried out on a cold rolled Al-6%Mg alloy sheet and on a copper rod. Experimental pole figures were obtained by means of neutron diffraction [2] and used for ODF calculation. The conformity between different results will be discussed. (author) [1] H.J. Bunge 1982, Texture Analysis in Material Science - Mathematical Methods, Butterworth, London.; [2] H.G. Brokmeier, U. Zink, R. Schnieber, B. Witassek, Material Science Forum (1998), 273-275, 277

Neutrino-nucleus cross-sections: a unified theoretical approach for nucleon knock-out, coherent and incoherent pion production

CERN Document Server

Martini, M; G. Chanfray; Marteau, J

2010-01-01

Neutrino-nucleus cross-sections are needed to interpret neutrino oscillation data, as neutrino detectors involve complex nuclei. We present a theory of neutrino interactions with nuclei aimed at a unified description of the partial cross-sections, namely quasi-elastic and multi-nucleon emission, coherent and incoherent single pion production. We compare our approach to the available neutrino experimental data on carbon. We also discuss the evolution of the neutrino cross-sections with the mass number in view of future precision ex- periments which will use a liquid argon chamber.

Measurements of the total neutron cross-sections of poly- and mono-germanium crystals at neutron energies below 1 eV

International Nuclear Information System (INIS)

Maayouf, R.M.A.; Abdel-Kawy, A.; Abbas, Y.; Habib, N.; Adib, M.; Hamouda, I.

1983-12-01

Total neutron cross-section measurements have been performed for poly and mono-germanium crystals in the energy range from 2 meV-1eV. The measurements were performed using two TOF and a double axis crystal spectrometer installed at the ET-RR-1 reactor. The obtained neutron cross-sections were analyzed using the single level Breit-Wigner formula. The coherent scattering amplitude was determined from the Bragg reflections observed in the total neutron cross-section of Ge and the analysis of its neutron diffraction pattern. The incoherent and thermal diffuse scattering cross-sections of Ge were estimated from the analysis of the total cross-section data obtained for Ge mono-crystal

Computer simulation of the anomalous elastic behavior of thin films and superlattices

International Nuclear Information System (INIS)

Wolf, D.

1992-10-01

Atomistic simulations are reviewed that elucidate the causes of the anomalous elastic behavior of thin films and superlattices (the so-called supermodulus effect). The investigation of free-standing thin films and of superlattices of grain boundaries shows that the supermodulus effect is not an electronic but a structural interface effect intricately connected with the local atomic disorder at the interfaces. The consequent predictions that (1) coherent strained-layer superlattices should show the smallest elastic anomalies and (2) the introduction of incoherency at the interfaces should enhance all anomalies are validated by simulations of dissimilar-material superlattices. 38 refs, 10 figs

Non-elastic cross-sections for neutron interactions with carbon and oxygen above 14 MeV

International Nuclear Information System (INIS)

Brenner, D.J.; Prael, R.E.

1985-01-01

In the light of the new generation of high energy (less than or equal to 80 MeV) neutron therapy facilities currently being tested, the need for neutron kerma factors in the range from 15 to 80 MeV on carbon and oxygen has become of urgent importance. Not enough experimental data currently exist or are likely to be measured soon, so a nuclear model is essential for interpolation or, less satisfactorily, extrapolation of available data. The use of a suitable model, applicable to light nuclei, is shown to be crucial. Such a model is described, and good agreement between its results and the experimental data in the energy range of interest is reported. Comparisons between the model predictions and the ENDF/B-V evaluation of the non-elastic cross section for carbon between 15 and 20 MeV indicate that a re-evaluation of ENDF is required. 35 refs., 12 figs., 6 tabs

Vibrations and reorientations of H2O molecules in [Sr(H2O)6]Cl2 studied by Raman light scattering, incoherent inelastic neutron scattering and proton magnetic resonance.

Science.gov (United States)

Hetmańczyk, Joanna; Hetmańczyk, Lukasz; Migdał-Mikuli, Anna; Mikuli, Edward; Florek-Wojciechowska, Małgorzata; Harańczyk, Hubert

2014-04-24

Vibrational-reorientational dynamics of H2O ligands in the high- and low-temperature phases of [Sr(H2O)6]Cl2 was investigated by Raman Spectroscopy (RS), proton magnetic resonance ((1)H NMR), quasielastic and inelastic incoherent Neutron Scattering (QENS and IINS) methods. Neutron powder diffraction (NPD) measurements, performed simultaneously with QENS, did not indicated a change of the crystal structure at the phase transition (detected earlier by differential scanning calorimetry (DSC) at TC(h)=252.9 K (on heating) and at TC(c)=226.5K (on cooling)). Temperature dependence of the full-width at half-maximum (FWHM) of νs(OH) band at ca. 3248 cm(-1) in the RS spectra indicated small discontinuity in the vicinity of phase transition temperature, what suggests that the observed phase transition may be associated with a change of the H2O reorientational dynamics. However, an activation energy value (Ea) for the reorientational motions of H2O ligands in both phases is nearly the same and equals to ca. 8 kJ mol(-1). The QENS peaks, registered for low temperature phase do not show any broadening. However, in the high temperature phase a small QENS broadening is clearly visible, what implies that the reorientational dynamics of H2O ligands undergoes a change at the phase transition. (1)H NMR line is a superposition of two powder Pake doublets, differentiated by a dipolar broadening, suggesting that there are two types of the water molecules in the crystal lattice of [Sr(H2O)6]Cl2 which are structurally not equivalent average distances between the interacting protons are: 1.39 and 1.18 Å. However, their reorientational dynamics is very similar (τc=3.3⋅10(-10) s). Activation energies for the reorientational motion of these both kinds of H2O ligands have nearly the same values in an experimental error limit: and equal to ca. 40 kJ mole(-1). The phase transition is not seen in the (1)H NMR spectra temperature dependencies. Infrared (IR), Raman (RS) and inelastic

The neutron elastic scatterirg differential cross sections in energy range below 440 keV

International Nuclear Information System (INIS)

Zo In Ok; Nikolenko, V.G.; Popov, A.B.; Samosvat, G.S.

1985-01-01

The intensities of elastically scattered neutrons have been measured on Ti, Ni, Fe, Zn, Ge, Se, Zr, Mo, Ru, Rh, Pd, Ag, Cd, 116 Sn, 117 Sn, 118 Sn, 119 Sn, 120 Sn, 122 Sn, 124 Sn, Te, Ta, W, Re targets at 45 deg, 90 deg and 135 deg angles on the IBR-30 reactor. The differential cross sections were descried by the formula σ(THETA)=σsub(s)/σ4π[1+ωsub(1)Psub(1)(cos THETA)+ωsub(2)Psub(2)(cos THETA)]. The tables on σsub(s)(E), ω 1 (E) and ω 2 (E) obtained from the experimental data are given

Incidental experiences of affective coherence and incoherence influence persuasion.

Science.gov (United States)

Huntsinger, Jeffrey R

2013-06-01

When affective experiences are inconsistent with activated evaluative concepts, people experience what is called affective incoherence; when affective experiences are consistent with activated evaluative concepts, people experience affective coherence. The present research asked whether incidental feelings of affective coherence and incoherence would regulate persuasion. Experiences of affective coherence and incoherence were predicted and found to influence the processing of persuasive messages when evoked prior to receipt of such messages (Experiments 1 and 3), and to influence the confidence with which thoughts generated by persuasive messages were held when evoked after presentation of such messages (Experiments 2 and 3). These results extend research on affective coherence and incoherence by showing that they exert a broader impact on cognitive activity than originally assumed.

Neutron Inelastic Scattering Study of Liquid Argon

Energy Technology Data Exchange (ETDEWEB)

Skoeld, K; Rowe, J M; Ostrowski, G [Solid State Science Div., Argonne National Laboratory, Argonne, Illinois (US); Randolph, P D [Nuclear Technology Div., Idaho Nuclear Corporation, Idaho Falls, Idaho (US)

1972-02-15

The inelastic scattering functions for liquid argon have been measured at 85.2 K. The coherent scattering function was obtained from a measurement on pure A-36 and the incoherent function was derived from the result obtained from the A-36 sample and the result obtained from a mixture of A-36 and A-40 for which the scattering is predominantly incoherent. The data, which are presented as smooth scattering functions at constant values of the wave vector transfer in the range 10 - 44/nm, are corrected for multiple scattering contributions and for resolution effects. Such corrections are shown to be essential in the derivation of reliable scattering functions from neutron scattering data. The incoherent data are compared to recent molecular dynamics results and the mean square displacement as a function of time is derived. The coherent data are compared to molecular dynamics results and also, briefly, to some recent theoretical models

Neutron energy measurement for practical applications

Indian Academy of Sciences (India)

M V Roshan

2018-02-07

. Elastic scattering of monoenergetic α-particles from neutron collision enables neutron energy measurement by calculating the amount of deviation from the position where collision takes place. The neutron numbers with ...

Neutron scattering investigations of the properties of the x - T phase diagram of Rb sub 1 sub - sub x (NH sub 4) sub x I mixed crystals

CERN Document Server

Smirnov, L S; Savenko, B N

2002-01-01

The x - T phase diagram of Rb sub 1 sub - sub x (NH sub 4) sub x I is studied using samples with the ammonium concentration 0.01neutron powder diffraction and inelastic incoherent neutron scattering. The results of powder diffraction studies show that at low temperatures a phase transition from alpha-phase to beta-phase is observed at ammonium concentrations x = 0.50 and x = 0.66. Inelastic incoherent neutron scattering detects a region of the orientional glass state at ammonium concentrations 0.29

Color transparency in incoherent electroproduction of ρ mesons off nuclei

International Nuclear Information System (INIS)

Nemchik, J.; Kopeliovich, B. Z.; Potashnikova, I. K.

2013-01-01

Color transparency (CT) phenomena in elastic electroproduction of vector mesons off nuclei are usually infected by the onset of coherence length (CL) effects. However, at low energies corresponding to the CLAS experiment at Jefferson Lab (JLab), one can study practically the net CT effects, since CL is much shorter than the nuclear radius. We investigate various manifestations of CT effects using rigorous quantum mechanical approach based on the path integral technique. We include also the effects of ρ meson decay inside the nucleus leading to a rise of the nuclear suppression towards small values of Q 2 . Motivated by the last CLAS data we predict the A, Q 2 and l c dependence of nuclear transparency for ρ 0 mesons produced incoherently off nuclei. We also perform predictions for expected signal of CT corresponding to the planned JLab upgrade to 12 GeV electron beam.

Color transparency in incoherent electroproduction of {rho} mesons off nuclei

Energy Technology Data Exchange (ETDEWEB)

Nemchik, J. [Institute of Experimental Physics SAS, Watsonova 47, 04001 Kosice, Slovakia and Czech Technical University, FNSPE, Brehova 7, 11519 Praque (Czech Republic); Kopeliovich, B. Z.; Potashnikova, I. K. [Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile)

2013-04-15

Color transparency (CT) phenomena in elastic electroproduction of vector mesons off nuclei are usually infected by the onset of coherence length (CL) effects. However, at low energies corresponding to the CLAS experiment at Jefferson Lab (JLab), one can study practically the net CT effects, since CL is much shorter than the nuclear radius. We investigate various manifestations of CT effects using rigorous quantum mechanical approach based on the path integral technique. We include also the effects of {rho} meson decay inside the nucleus leading to a rise of the nuclear suppression towards small values of Q{sup 2}. Motivated by the last CLAS data we predict the A, Q{sup 2} and l{sub c} dependence of nuclear transparency for {rho}{sup 0} mesons produced incoherently off nuclei. We also perform predictions for expected signal of CT corresponding to the planned JLab upgrade to 12 GeV electron beam.

Investigation of solid solution of hydrogen in α-manganese by neutron diffraction and inelastic neutron scattering

International Nuclear Information System (INIS)

Fedotov, V.K.; Antonov, V.E.; Kolesnikov, A.I.; Kornell, K.; Vipf, G.; Grosse, G.; Vagner, F.Eh.; Sikolenko, V.V.; Sumin, V.V.; )

1997-01-01

The FCC-lattice of the solid solution α-MnH 0.073 with the mass of 8.45 g is investigated by the neutron diffraction method and the inelastic neutron scattering technique. The neutron diffraction measurements are made by the diffractometer D1B with pyrographite monochromator and the high-resolution Fourier diffractometer HRFD at 300 K. The study of the inelastic incoherent neutron scattering is carried out by means of the inverse geometry spectrometer KDSOG-M at 90 K. The comparative analysis of α-MnH 0.073 and α-Mn spectra is fulfilled for the more correct separation of effects of hydrogen introduction. It is found out that the structure of the solid solution α-MnH 0.073 belongs to the same spatial group I-43m as the structure of α-Mn [ru

An Optical Model Study of Neutrons Elastically Scattered by Iron, Nickel, Cobalt, Copper, and Indium in the Energy Region 1.5 to 7.0 MeV

Energy Technology Data Exchange (ETDEWEB)

Holmqvist, B; Wiedling, T

1967-03-15

Angular distributions of elastically scattered neutrons have been measured for cobalt and copper at nine energies between 1.5 and 7.0 MeV, for natural iron at 4.6 MeV, for natural nickel and indium at four energies between 3.0 and 4.6 MeV, by using time-of-flight technique. The observed angular distributions were corrected for neutron flux attenuation, multiple elastic scattering, and the finite geometry of the source-sample-detector system by using a Monte Carlo program. Theoretical angular distributions have been fitted to the experimental angular distributions by using an optical model potential with Saxon-Woods form factors. A computer program was used to find parameter values of the potential giving the best fittings to the experimental angular distributions.

Elastic neutron scattering of dry and rehydrated trehalose coated carboxy-myoglobin

International Nuclear Information System (INIS)

Librizzi, Fabio; Vitrano, Eugenio; Paciaroni, Alessandro; Cordone, Lorenzo

2008-01-01

We report here a comparison between the hydrogen atoms mean square displacements measured by elastic neutron scattering on trehalose coated carboxy-myoglobin, at ILL on the backscattering spectrometers IN13 and IN16. An inconsistency is observed when comparing the mean square displacements measured on the two spectrometer, on samples of identical composition, since they resulted of larger amplitude on IN13 (either in condition of drought or after overnight rehydration under 75% D 2 O atmosphere), notwithstanding the lower time window accessible on this instrument with respect to IN16. Such inconsistency disappears when the data obtained on this last spectrometer are analyzed in two separate ranges of the exchanged wave vector q. The analysis of the data collected on IN13 in terms of the two-well model [W. Doster, S. Cusak, W. Petry, Nature 337 (1989) 754] gives relevant information on the enthalpy and entropy values involved in the interconversion among substates in dry and rehydrated trehalose coated protein samples

Elastic neutron scattering of dry and rehydrated trehalose coated carboxy-myoglobin

Energy Technology Data Exchange (ETDEWEB)

Librizzi, Fabio; Vitrano, Eugenio [Dipartimento di Scienze Fisiche e Astronomiche and CNISM, Universita di Palermo, Via Archirafi 36, I-90123 Palermo (Italy); Paciaroni, Alessandro [Dipartimento di Fisica dell' Universita di Perugia, INFM-CRS SOFT and CEMIN - Centro di Eccellenza per i Materiali Innovativi e Nanostrutturati, Via A. Pascoli, I-06123 Perugia (Italy); Cordone, Lorenzo [Dipartimento di Scienze Fisiche e Astronomiche and CNISM, Universita di Palermo, Via Archirafi 36, I-90123 Palermo (Italy)], E-mail: cordone@fisica.unipa.it

2008-04-18

We report here a comparison between the hydrogen atoms mean square displacements measured by elastic neutron scattering on trehalose coated carboxy-myoglobin, at ILL on the backscattering spectrometers IN13 and IN16. An inconsistency is observed when comparing the mean square displacements measured on the two spectrometer, on samples of identical composition, since they resulted of larger amplitude on IN13 (either in condition of drought or after overnight rehydration under 75% D{sub 2}O atmosphere), notwithstanding the lower time window accessible on this instrument with respect to IN16. Such inconsistency disappears when the data obtained on this last spectrometer are analyzed in two separate ranges of the exchanged wave vector q. The analysis of the data collected on IN13 in terms of the two-well model [W. Doster, S. Cusak, W. Petry, Nature 337 (1989) 754] gives relevant information on the enthalpy and entropy values involved in the interconversion among substates in dry and rehydrated trehalose coated protein samples.

A Neutron Elastic Scattering Study of Chromium, Iron and Nickel in the Energy Region 1.77 to 2.76 MeV

Energy Technology Data Exchange (ETDEWEB)

Holmqvist, B; Johansson, S G; Lodin, G; Wiedling, T [AB Atomenergi, Nyko eping (Sweden); Salama, M [Reactor and Neutron Physics Dept., Atomic Energy Es tablishment, Cairo (Egypt)

1970-07-01

Elastic neutron scattering measurements have been performed on the natural elements chromium, iron and nickel. Angular distributions were recorded in the interval 20 to 160 deg at several energies in the region 1.77 to 2.76 MeV. The experimental data were analysed in terms of the optical model, applying a spherical nuclear potential.

Neutron noise analysis of BWR using time series analysis

International Nuclear Information System (INIS)

Fukunishi, Kohyu

1976-01-01

The main purpose of this paper is to give more quantitative understanding of noise source in neutron flux and to provide a useful tool for the detection and diagnosis of reactor. The space dependent effects of distributed neutron flux signals at the axial direction of two different strings are investigated by the power contribution ratio among neutron fluxes and the incoherent noise spectra of neutron fluxes derived from autoregressive spectra. The signals are measured on the medium sized commercial BWR of 460 MWe in Japan. From the obtained results, local and global noise sources in neutron flux are discussed. This method is indicated to be a useful tool for detection and diagnosis of anomalous phenomena in BWR. (orig./RW) [de

Development and applications of the reverse neutron time-of-flight method with Fourier-type beam chopper

International Nuclear Information System (INIS)

Antson, O.

1991-09-01

The neutron powder diffraction method has been applied to the crystal structure analysis of high-temperature superconductors such as La 0 .8Sr 0 .2CuO 4 - y , YBa 2 Cu 3 O 7 - y and Bi 2 Sr 2 CaCu 2 O 8 + y optically active yttriumformate Y(HCOO) 3 , and β phase of deuterated acetonitrile, CD 3 CN. The structural information, containing symmetry, positional and thermal parameters, occupation factors and the order parameter, was obtained by measuring the coherent elastic scattering cross-section. The Rietveld profile refinement method was used for the extraction of structural parameters from experimental data. The diffraction spectra were obtained by measuring the time-of-flight distribution of neutrons with a Fourier-type beam chopper. The neutron diffraction spectrum is created by the on-line synthesis of the cross-correlation function between the beam modulation function and the detector intensity. Such an operational mode, called the reverse time-of-flight method, has many unique properties. The possibility of filtering out a low-frequency part of a diffraction spectrum, eg. incoherent background, by a properly selected band-pass filter has been studied. One of the practical applications of the reverse time-of-flight method, the Mini-Sfinks facility, is described with technical details, and its operational characteristics are compared with other high-resolution instruments

Dynamics of water and ions in clays of type montmorillonite by microscopic simulation and quasi-elastic neutron scattering; Dynamique de l'eau et des ions dans des argiles de type montmorillonite par simulation microscopique et diffusion quasi-elastique des neutrons

Energy Technology Data Exchange (ETDEWEB)

Malikova, N

2005-09-15

Montmorillonite clays in low hydration states, with Na{sup +} and Cs{sup +} compensating counter ions, are investigated by a combination of microscopic simulation and quasi-elastic neutron scattering to obtain information on the local structure and dynamics of water and ions in the interlayer. At first predictions of simulation into the dynamics of water and ions at elevate temperatures are shown (0 deg C 80 deg C, pertinent for the radioactive waste disposal scenario) Marked difference is observed between the modes of diffusion of the Na{sup +} and C{sup +} counter ions. In water dynamics, a significant step towards bulk water behaviour is seen on transition from the mono- to bilayer states. Secondly, a detailed comparison between simulation and quasi-elastic neutron scattering (Neutron Spin Echo and Time-of-Flight) regarding ambient temperature water dynamics is presented. Overall, the approaches are found to be in good agreement with each other and limitations of each of the methods are clearly shown. (author)

Dynamics of crystalline acetanilide: Analysis using neutron scattering and computer simulation

Science.gov (United States)

Hayward, R. L.; Middendorf, H. D.; Wanderlingh, U.; Smith, J. C.

1995-04-01

The unusual temperature dependence of several optical spectroscopic vibrational bands in crystalline acetanilide has been interpreted as providing evidence for dynamic localization. Here we examine the vibrational dynamics of crystalline acetanilide over a spectral range of ˜20-4000 cm-1 using incoherent neutron scattering experiments, phonon normal mode calculations and molecular dynamics simulations. A molecular mechanics energy function is parametrized and used to perform the normal mode analyses in the full configurational space of the crystal i.e., including the intramolecular and intermolecular degrees of freedom. One- and multiphonon incoherent inelastic neutron scattering intensities are calculated from harmonic analyses in the first Brillouin zone and compared with the experimental data presented here. Phonon dispersion relations and mean-square atomic displacements are derived from the harmonic model and compared with data derived from coherent inelastic neutron scattering and neutron and x-ray diffraction. To examine the temperature effects on the vibrations the full, anharmonic potential function is used in molecular dynamics simulations of the crystal at 80, 140, and 300 K. Several, but not all, of the spectral features calculated from the molecular dynamics simulations exhibit temperature-dependent behavior in agreement with experiment. The significance of the results for the interpretation of the optical spectroscopic results and possible improvements to the model are discussed.

Neutrons in biology

International Nuclear Information System (INIS)

Funahashi, Satoru; Niimura, Nobuo.

1993-01-01

The start of JRR-3M in 1990 was a great epoch to the neutron scattering research in Japan. Abundant neutron beam generated by the JRR-3M made it possible to widen the research field of neutron scattering in Japan. In the early days of neutron scattering, biological materials were too difficult object to be studied by neutrons not only because of their complexity but also because of the strong incoherent scattering by hydrogen. However, the remarkable development of the recent neutron scattering and its related sciences, as well as the availability of higher flux, has made the biological materials one of the most attractive subjects to be studied by neutrons. In early September 1992, an intensive workshop titled 'Neutrons in Biology' was held in Hitachi City by making use of the opportunity of the 4th International Conference on Biophysics and Synchrotron Radiation (BSR92) held in Tsukuba. The workshop was organized by volunteers who are eager to develop the researches in this field in Japan. Numbers of outstanding neutron scattering biologists from U.S., Europe and Asian countries met together and enthusiastic discussions were held all day long. The editors believe that the presentations at the workshop were so invaluable that it is absolutely adequate to put them on record as an issue of JAERI-M and to make them available for scientists to refer to in order to further promote the research in the future. (author)

Using quasi-elastic neutron diffraction to study positive electrode for lithium and sodium-ion batteries

International Nuclear Information System (INIS)

Pramudita, James C.; Sharma, Neeraj

2015-01-01

Sodium-ion batteries has recently been proposed as the alternative for lithium-ion batteries to be the low cost energy storage system. However, challenges still remains for the development of sodium-ion batteries. Optimization of electrode materials and electrolyte capable of insertion/extraction of sodium-ion in a safe and economic way under high current density is needed in order to produce commercially viable sodium-ion batteries. While possible positive electrode material is more prevalent than negative electrode material, many of these material still need further understanding. Quasi-elastic Neutron Scatteringis a technique that utilize the inelastic Neutron Scatteringthat can be used to study solid-state diffusion in materials. This technique can be used to study the diffusion of sodium-ion under electric field through the electrolyte and positive electrode materials in order to further understand the mechanism of sodium insertion/extraction in a working battery. This technique can also be used to study available positive electrode material for lithium-ion batteries to further understand the mechanism of lithium-ion diffusion in current working lithiumion batteries.

Future possibilities with intermediate-energy neutron beams

International Nuclear Information System (INIS)

Brady, F.P.

1987-01-01

Future possibilities for using neutrons of intermediate energies (50 - 200 MeV) as a probe of the nucleus are discussed. Some of the recent thinking concerning a systematic approach for studying elastic and inelastic scattering of electrons and hadrons and the important role of medium- and intermediate-energy neutrons in such a programme is reviewed. The advantages of neutrons in this energy range over neutrons with lower energies and over intermediate-energy pions for determining nuclear-transition and ground state densities, and for distinguishing proton from neutron density (isovector sensitivity), are noted. The important role of (n,p) charge exchange reactions in nuclear excitation studies is also reviewed. Experimental methods for utilizing neutrons as probes in elastic, inelastic, and charge exchange studies at these energies are discussed

On the neutron diffraction in a crystal in the field of a standing laser wave

International Nuclear Information System (INIS)

Grigoryan, K.K.; Hayrapetyan, A.G.; Petrosyan, R.G.

2010-01-01

The possibility of high-energy neutron diffraction in a crystal is shown by applying the solution of time-dependent Schroedinger equation for a neutron in the field of a standing laser wave. The scattering picture is examined within the framework of non-stationary S-matrix theory, where the neutron-laser field interaction is considered exactly and the neutron-crystal interaction is considered as a perturbation described by Fermi pseudopotential (Farri representation). The neutron-crystal interaction is elastic, and the neutron-laser field interaction has both inelastic and elastic behaviors which results in the observation of an analogous to the Kapitza-Dirac effect for neutrons. The neutron scattering probability is calculated and the analysis of the results are adduced. Both inelastic and elastic diffraction conditions are obtained and the formation of a 'sublattice' is illustrated in the process of neutron-photon-phonon elastic interaction.

mQfit, a new program for analyzing quasi-elastic neutron scattering data

Directory of Open Access Journals (Sweden)

Martinez Nicolas

2015-01-01

Full Text Available Analysis of Quasi-elastic Neutron Scattering (QENS data of complex systems such as biological or soft matter samples in a comprehensive and explicit way often requires great efforts. Most popular software only allows to fit spectra originating from one single instrument and does not permit to extract parameters from a model that is fitted simultaneously to data taken at different instrumental resolutions. We present here a new program, mQfit (multiple QENS dataset fitting, that enables to fit QENS data taken at different spectrometers (with typical resolutions between 0.01 and 0.1 meV and momentum transfer ranges. This allows drastically reducing the number of fitting parameters. The routine is implemented with a user friendly Graphical User's Interface (GUI, and freely available. As an example, we will present results obtained on E. coli bacterial pellets, and compare them to values published in the literature.

Monte Carlo estimation of the influence of elastic scattering anisotropy on the neutron flux in a nuclear reactor cell; Monte Carlo procena uticaja anizotropije elasticnog rasejanja na vrednost neutronskog fluksa u celiji nuklearnog reaktora

Energy Technology Data Exchange (ETDEWEB)

Kocic, A [Institute of nuclear sciences Boris Kidric, Vinca, Beograd (Yugoslavia)

1974-07-01

Anisotropy of neutron elastic scattering is a problem of special importance in solving the Boltzmann transport equation numerically. This is not the case when Monte Carlo method is applied. Estimation of the influence of elastic scattering anisotropy on the neutron flux is treated in order to justify the application of Monte Carlo method which is computer time consuming. Correlation procedure was applied for the study of this influence. One group case was used as an example to enable comparison of other methods.

Investigation of the reflection of fast neutrons

International Nuclear Information System (INIS)

Devillers, Christian; Hasselin, Gilbert

1964-10-01

The authors report the study of the reflection of fast neutrons on a plane plate having a finite and varying thickness and an infinite width. Calculations are performed by using a Monte-Carlo method which allows the number, the energy, the direction, the emergence point of neutrons reflected on a plate, to be computed with respect to the energy and direction of incident neutrons. The author present how paths, elastic and inelastic shocks, direction after shock are calculated. Different information are calculated: the numbers of elastic shocks, inelastic shocks and transmitted neutrons, the number, energy and dose albedo, the spectrum and angular distribution, the distribution of neutron in terms of energy and direction

Neutron skin of 208 Pb in consistency with neutron star observations

CERN Document Server

Miyazaki, K

2007-01-01

The renormalized meson-nucleon couplings are applied to the relativistic optical model of p-208Pb elastic scattering at T_{lab}=200MeV. We calculate the strength of the vector potential at nuclear center as varying the neutron radius of 208Pb. The neutron skin thickness S_{n} is determined in the comparison of the calculated potential with the phenomenological one. We find a value S_{n}=0.118fm being consistent with the astronomical observations of massive neutron stars (NSs), the standard scenario of NS cooling and the experimental nuclear symmetry energy in terrestrial laboratory. The value is complementary to the previous result S_{n}=0.119fm in the analysis of elastic scattering above T_{lab}=500MeV within the relativistic impulse optical model.

Latest developments of neutron scattering instrumentation at the Juelich Centre for Neutron Science

International Nuclear Information System (INIS)

Ioffe, Alexander

2013-01-01

Jülich Centre for Neutron Science (JCNS) is operating a number of world-class neutron scattering instruments situated at the most powerful and advanced neutron sources (FRM II, ILL and SNS) and is continuously undertaking significant efforts in the development and upgrades to keep this instrumentation in line with the continuously changing scientific request. These developments are mostly based upon the latest progress in neutron optics and polarized neutron techniques. For example, the low-Q limit of the suite of small angle-scattering instruments has been extended to 4·10 -5 Å -1 by the successful use of focusing optics. A new generation of correction elements for the neutron spin-echo spectrometer has allowed for the use of the full field integral available, thus pushing further the instrument resolution. A significant progress has been achieved in the developments of 3 He neutron spin filters for purposes of the wide-angle polarization analysis for off-specular reflectometry and (grazing incidence) small-angle neutron scattering, e.g. the on-beam polarization of 3 He in large cells is allowing to achieve a high neutron beam polarization without any degradation in time. The wide Q-range polarization analysis using 3 He neutron spin filters has been implemented for small-angle neutron scattering that lead to the reduction up to 100 times of the intrinsic incoherent background from non-deuterated biological molecules. Also the work on wide-angle XYZ magnetic cavities (Magic PASTIS) will be presented. (author)

Towards sub-{Angstrom} resolution through incoherent imaging

Energy Technology Data Exchange (ETDEWEB)

Pennycook, S.J.; Chisholm, M.F. [Oak Ridge National Lab., TN (United States); Nellist, P.D. [Cavendish Lab., Cambridge, (United Kingdom)

1997-04-01

As first pointed out by Lord Rayleigh a century ago, incoherent imaging offers a substantial resolution enhancement compared to coherent imaging, together with freedom from phase contrast interference effects and contrast oscillations. In the STEM configuration, with a high angle annular detector to provide the transverse incoherence, the image also shows strong Z-contrast, sufficient in the case of a 300 kV STEM to image single Pt and Rh atoms on a {gamma}-alumina support. The annular detector provides complementarity to a bright field detector of the same size. For weakly scattering specimens, it shows greater contrast than the incoherent bright field image, and also facilitates EELS analysis at atomic resolution, using the Z-contrast image to locate the probe with sub-{angstrom} precision. The inner radius of the annular detector can be chosen to reduce the transverse coherence length to well below the spacings needed to resolve the object, a significant advantage compared to light microscopy.

Neutron emission from projectile-like and target-like fragments in the 18O+48Ti reaction at E(18O)=116 MeV

International Nuclear Information System (INIS)

Chambon, B.; Drain, D.; Pastor, C.; Dauchy, A.; Giorni, A.; Morand, C.

1982-07-01

Angular correlations between neutrons and projectile-like fragments detected near the grazing angle were analysed by assuming two incoherent neutrons sources. One source describes slower neutrons evaporated by target-like fragments in equilibrium. The faster, forward-peaked neutrons originate from a second source strongly correlated with the projectile-like fragments with regards to velocity and direction. In some cases neutron emission may even be attributed to known neutron emitter levels in excited ejectiles

Magnetism and magnetic materials probed with neutron scattering

International Nuclear Information System (INIS)

Velthuis, S.G.E. te; Pappas, C.

2014-01-01

Neutron scattering techniques are becoming increasingly accessible to a broader range of scientific communities, in part due to the onset of next-generation, high-power spallation sources, high-performance, sophisticated instruments and data analysis tools. These technical advances also advantageously impact research into magnetism and magnetic materials, where neutrons play a major role. In this Current Perspective series, the achievements and future prospects of elastic and inelastic neutron scattering, polarized neutron reflectometry, small angle neutron scattering, and neutron imaging, are highlighted as they apply to research into magnetic frustration, superconductivity and magnetism at the nanoscale. - Highlights: • Introduction to Current Perspective series titled Magnetism and Magnetic Materials probed with Neutron Scattering. • Elastic and inelastic neutron scattering in systems with magnetic frustration and superconductivity. • Small angle neutron scattering and polarized neutron reflectometry in studying magnetism at the nanoscale. • Imaging of magnetic fields and domains

Magnetism and magnetic materials probed with neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Velthuis, S.G.E. te, E-mail: tevelthuis@anl.gov [Materials Science Division, Argonne National Laboratory, 9700 S Cass Ave, Argonne, IL 60439 (United States); Pappas, C. [Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629JB Delft (Netherlands)

2014-01-15

Neutron scattering techniques are becoming increasingly accessible to a broader range of scientific communities, in part due to the onset of next-generation, high-power spallation sources, high-performance, sophisticated instruments and data analysis tools. These technical advances also advantageously impact research into magnetism and magnetic materials, where neutrons play a major role. In this Current Perspective series, the achievements and future prospects of elastic and inelastic neutron scattering, polarized neutron reflectometry, small angle neutron scattering, and neutron imaging, are highlighted as they apply to research into magnetic frustration, superconductivity and magnetism at the nanoscale. - Highlights: • Introduction to Current Perspective series titled Magnetism and Magnetic Materials probed with Neutron Scattering. • Elastic and inelastic neutron scattering in systems with magnetic frustration and superconductivity. • Small angle neutron scattering and polarized neutron reflectometry in studying magnetism at the nanoscale. • Imaging of magnetic fields and domains.

Application of Incoherent Inelastic Neutron Scattering in Pharmaceutical Analysis

DEFF Research Database (Denmark)

Bordallo, Heloisa N.; A. Zakharov, Boris; Boidyreva, E.V.

2012-01-01

This study centers on the use of inelastic neutron scattering as an alternative tool for physical characterization of solid pharmaceutical drugs. On the basis of such approach, relaxation processes in the pharmaceutical compound phenacetin (p-ethoxyacetanilide, C(10)H(13)NO(2)) were evidenced...... contributes to understanding the relationships between intermolecular hydrogen bonds, intramolecular dynamics, and conformational flexibility in pharmaceuticals on a molecular level, which can help in evaluating phase stability with respect to temperature variations on processing or on storage, and is related...

Changes in the anisotropy of oriented membrane dynamics induced by myelin basic protein

Energy Technology Data Exchange (ETDEWEB)

Natali, F. [OGG-INFM, Grenoble (France); Gliozzi, A.; Rolandi, R.; Relini, A. [Dipartimento di Fisica and Istituto Nazionale per la Fisica della Materia, Universita di Genova (Italy); Cavatorta, P.; Deriu, A. [Dipartimento di Fisica and Istituto Nazionale per la Fisica della Materia, Universita di Parma (Italy); Fasano, A. [Dipartimento di Biochimica e Biologia Molecolare, Universita di Bari (Italy); Riccio, P. [Dipartimento di Biologia D.B.A.F., Universita della Basilicata, Potenza (Italy)

2002-07-01

We report recent results showing the evidence of the effect induced by physiological amounts of myelin basic protein (MBP) on the dynamics of dimyristoyl L-a-phosphatidic acid (DMPA) membranes. Incoherent elastic neutron scattering scans, performed over a wide temperature range, have shown that the anisotropy of motions in oriented membranes is significantly enhanced by the presence of MBP. (orig.)

Proposal for the design of a small-angle neutron scattering facility at a pulsed neutron source

International Nuclear Information System (INIS)

Kley, W.

1980-01-01

The intensity-resolution-background considerations of an optimized small angle neutron scattering facility are reviewed for the special case of a pulsed neutron source. In the present proposal we conclude that for 'true elastic scattering experiments' filters can be used instead of expensive neutron guide tubes since low background conditions can be achieved by a combined action of filters as well as a proper time gating of the twodimensional detector. The impinging neutron beam is monochromatized by phasing a disk chopper to the neutron source pulses and in the scattered beam a second disk chopper is used to eliminate the inelastically scattered neutrons. Therefore, no time of fligh analysis is necessary for the scattered neutron intensity and true-elastic conditions are obtained by simply gating the two-dimensional detector. Considering a 4 m thick shield for the pulsed neutron source and choosing for optimum conditions a detector area element of (2.5 cm) 2 and a sample area of (1.25 cm) 2 , than for a minimum sample-detector-distance of 1.5 m, a maximum neutron source diameter of 6.67 cm is required in order to maintain always the optimum intensity- and resolution requirements

Dynamics of liquid N2 studied by neutron inelastic scattering

DEFF Research Database (Denmark)

Pedersen, Karen Schou; Carneiro, Kim; Hansen, Flemming Yssing

1982-01-01

Neutron inelastic-scattering data from liquid N2 at wave-vector transfer κ between 0.18 and 2.1 Å-1 and temperatures ranging from T=65-77 K are presented. The data are corrected for the contribution from multiple scattering and incoherent scattering. The resulting dynamic structure factor S (κ,ω)...

Neutron scattering studies in the actinide region

International Nuclear Information System (INIS)

Kegel, G.H.R.; Egan, J.J.

1993-09-01

This report discusses the following topics: Prompt fission neutron energy spectra for 235 U and 239 Pu; Two-parameter measurement of nuclear lifetimes; ''Black'' neutron detector; Data reduction techniques for neutron scattering experiments; Inelastic neutron scattering studies in 197 Au; Elastic and inelastic scattering studies in 239 Pu; and neutron induced defects in silicon dioxide MOS structures

Scattering of fast neutrons from elemental molybdenum

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.

1982-11-01

Differential broad-resolution neutron-scattering cross sections of elemental molybdenum were measured at 10 to 20 scattering angles distributed between 20 and 160 degrees and at incident-neutron energy intervals of approx. = 50 to 200 keV from 1.5 to 4.0 MeV. Elastically-scattered neutrons were fully resolved from inelastic events. Lumped-level inelastic-neutron-scattering cross sections were determined corresponding to observed excitation energies of; 789 +- 23, 195 +- 23, 1500 +- 34, 1617 +- 12, 1787, 1874, 1991, 2063 +- 24, 2296, 2569 and 2802 keV. An optical-statistical model was deduced from the measured elastic-scattering results. The experimental values were compared with the respective quantities given in ENDF/B-V

Optical image encryption method based on incoherent imaging and polarized light encoding

Science.gov (United States)

Wang, Q.; Xiong, D.; Alfalou, A.; Brosseau, C.

2018-05-01

We propose an incoherent encoding system for image encryption based on a polarized encoding method combined with an incoherent imaging. Incoherent imaging is the core component of this proposal, in which the incoherent point-spread function (PSF) of the imaging system serves as the main key to encode the input intensity distribution thanks to a convolution operation. An array of retarders and polarizers is placed on the input plane of the imaging structure to encrypt the polarized state of light based on Mueller polarization calculus. The proposal makes full use of randomness of polarization parameters and incoherent PSF so that a multidimensional key space is generated to deal with illegal attacks. Mueller polarization calculus and incoherent illumination of imaging structure ensure that only intensity information is manipulated. Another key advantage is that complicated processing and recording related to a complex-valued signal are avoided. The encoded information is just an intensity distribution, which is advantageous for data storage and transition because information expansion accompanying conventional encryption methods is also avoided. The decryption procedure can be performed digitally or using optoelectronic devices. Numerical simulation tests demonstrate the validity of the proposed scheme.

Broadband Dielectric Spectroscopy and Quasi-Elastic Neutron Scattering on Single-Ion Polymer Conductors

Science.gov (United States)

Soles, Christopher; Peng, Hua-Gen; Page, Kirt; Snyder, Chad; Pandy, Ashoutosh; Jeong, Youmi; Runt, James; NIST Collaboration; Pennsylvania Collaboration

2011-03-01

The application of solid polymer electrolytes in rechargeable batteries has not been fully realized after decades of research due to its low conductivity. Dramatic increases of the ion conductivity are needed and this progress requires the understanding of conduction mechanism. We address this topic in two fronts, namely, the effect of plasticizer additives and geometric confinement on the charge transfer mechanism. To this end, we combine broadband dielectric spectroscopy (BDS) to characterize the ion mobility and quasi-elastic neutron scattering (QENS) to quantify segmental motion on a single-ion model polymer electrolyte. Deuterated small molecules were used as plasticizers so that the segmental motion of the polymer electrolyte could be monitored by QENS to understand the mechanism behind the increased conductivity. Anodic aluminum oxide (AAO) membranes with well defined channel sizes are used as the matrix to study the transport of ions solvated in a 1D polymer electrolyte.

Expected anomalies of the neutron cross section near the liquid-glass transition

International Nuclear Information System (INIS)

Gotze, W.

1987-01-01

In the frameworks of a microscopic theory the anomalies of the neutron cross section near the liquid-glass transition are discussed. The central concept of the theory is the correlation function for density fluctuations of wave vector q and frequency ω. Its absorptive part is proportional to the dynamical structure factor S(q, ω), this is the scattering law for coherent neutron scattering. Tagged particle motion is evaluated as well and it yields the incoherent neutron scattering cross section S i (q, ω) in. The predictions of the theory for S(q, ω) and Si (q, ω) a q-ω domain are given

Optical bistability via quantum interference from incoherent pumping and spontaneous emission

International Nuclear Information System (INIS)

Sahrai, M.; Asadpour, S.H.; Sadighi-Bonabi, R.

2011-01-01

We theoretically investigate the optical bistability (OB) in a V-type three-level atomic system confined in a unidirectional ring cavity via incoherent pumping field. It is shown that the threshold of optical bistability can be controlled by the rate of an incoherent pumping field and by interference mechanism arising from the spontaneous emission and incoherent pumping field. We demonstrate that the optical bistability converts to optical multi-stability (OM) by the quantum interference mechanism. - Highlights: → We modulate the optical bistability (OB) in a four-level N-type atomic system. → The threshold of optical bistability can be controlled by the quantum interferences. → OB converts to optical multi-stability (OM) by the quantum interferences. → We discuss the effect of an incoherent pumping field on reduction of OB threshold.

Quasi-Elastic Neutron Scattering Studies of the Slow Dynamics of Supercooled and Glassy Aspirin

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yang [ORNL; Tyagi, M. [NCNR and University of Maryland; Mamontov, Eugene [ORNL; Chen, Sow-hsin H [ORNL

2011-01-01

Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 K down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent (Q) is independent of the wave vector transfer Q in the measured Q-range, and (ii) the structural relaxation time (Q) follows a power law dependence on Q. Consequently, the Q-independent structural relaxation time 0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of 0 can be fitted with the mode coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by M. Tokuyama in the measured temperature range. The calculated dynamic response function T(Q,t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows a direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement x2 and non-Gaussian parameter 2 extracted from the elastic scattering.

Handbook of neutron optics

CERN Document Server

Utsuro, Masahiko

2010-01-01

Written by authors with an international reputation, acknowledged expertise and teaching experience, this is the most up-to-date resource on the field. The text is clearly structured throughout so as to be readily accessible, and begins by looking at scattering of a scalar particle by one-dimensional systems. The second section deals with the scattering of neutrons with spin in one-dimensional potentials, while the third treats dynamical diffraction in three-dimensional periodic media. The final two sections conclude with incoherent and small angle scattering, and some problems of quantum mech

Constraining properties of high-density matter in neutron stars with magneto-elastic oscillations

Science.gov (United States)

Gabler, Michael; Cerdá-Durán, Pablo; Stergioulas, Nikolaos; Font, José A.; Müller, Ewald

2018-05-01

We discuss torsional oscillations of highly magnetized neutron stars (magnetars) using two-dimensional, magneto-elastic-hydrodynamical simulations. Our model is able to explain both the low- and high-frequency quasi-periodic oscillations (QPOs) observed in magnetars. The analysis of these oscillations provides constraints on the breakout magnetic-field strength, on the fundamental QPO frequency, and on the frequency of a particularly excited overtone. By performing a new set of simulations, we are able to derive for the first time empirical relations for a self consistent model including a superfluid core which describe these constraints quantitatively. We use these relations to generically constrain properties of high-density matter in neutron stars, employing Bayesian analysis. In spite of current uncertainties and computational approximations, our model-dependent Bayesian posterior estimates for SGR 1806-20 yield a magnetic-field strength \\bar{B}˜ 2.1^{+1.3}_{-1.0}× 10^{15} G and a crust thickness of Δ r = 1.6^{+0.7}_{-0.6} km, which are both in remarkable agreement with observational and theoretical expectations, respectively (1σ error bars are indicated). Our posteriors also favour the presence of a superfluid phase in the core, a relatively low stellar compactness, M/R star, and high shear speeds at the base of the crust, cs > 1.4 × 108 cm s-1. Although the procedure laid out here still has large uncertainties, these constraints could become tighter when additional observations become available.

High-level expression and deuteration of sperm whale myoglobin: A study of its solvent structure by X-ray and neutron diffraction methods

Energy Technology Data Exchange (ETDEWEB)

Shu, F. [State Univ. of New York, Stony Brook, NY (United States); Ramakrishnan, V. [Brookhaven National Laboratory, Upton, NY (United States); Schoenborn, B.P. [Los Alamos National Laboratory, NM (United States)

1994-12-31

Neutron diffraction has become one of the best ways to study light atoms, such as hydrogens. Hydrogen however has a negative coherent scattering factor, and a large incoherent scattering factor, while deuterium has virtually no incoherent scattering, but a large positive coherent scattering factor. Beside causing high background due to its incoherent scattering, the negative coherent scattering of hydrogen tends to cancel out the positive contribution from other atoms in a neutron density map. Therefore a fully deuterated sample will yield better diffraction data with stronger density in the hydrogen position. On this basis, a sperm whale myoglobin gene modified to include part of the A cII protein gene has been cloned into the T7 expression system. Milligram amounts of fully deuterated holo-myoglobin have been obtained and used for crystallization. The synthetic sperm whale myoglobin crystallized in P2{sub 1} space group isomorphous with the native protein crystal. A complete X-ray diffraction dataset at 1.5{Angstrom} has been collected. This X-ray dataset, and a neutron data set collected previously on a protonated carbon-monoxymyoglobin crystal have been used for solvent structure studies. Both X-ray and neutron data have shown that there are ordered hydration layers around the protein surface. Solvent shell analysis on the neutron data further has shown that the first hydration layer behaves differently around polar and apolar regions of the protein surface. Finally, the structure of per-deuterated myoglobin has been refined using all reflections to a R factor of 17%.

High-level expression and deuteration of sperm whale myoglobin: A study of its solvent structure by X-ray and neutron diffraction methods

International Nuclear Information System (INIS)

Shu, F.; Ramakrishnan, V.; Schoenborn, B.P.

1994-01-01

Neutron diffraction has become one of the best ways to study light atoms, such as hydrogens. Hydrogen however has a negative coherent scattering factor, and a large incoherent scattering factor, while deuterium has virtually no incoherent scattering, but a large positive coherent scattering factor. Beside causing high background due to its incoherent scattering, the negative coherent scattering of hydrogen tends to cancel out the positive contribution from other atoms in a neutron density map. Therefore a fully deuterated sample will yield better diffraction data with stronger density in the hydrogen position. On this basis, a sperm whale myoglobin gene modified to include part of the A cII protein gene has been cloned into the T7 expression system. Milligram amounts of fully deuterated holo-myoglobin have been obtained and used for crystallization. The synthetic sperm whale myoglobin crystallized in P2 1 space group isomorphous with the native protein crystal. A complete X-ray diffraction dataset at 1.5 Angstrom has been collected. This X-ray dataset, and a neutron data set collected previously on a protonated carbon-monoxymyoglobin crystal have been used for solvent structure studies. Both X-ray and neutron data have shown that there are ordered hydration layers around the protein surface. Solvent shell analysis on the neutron data further has shown that the first hydration layer behaves differently around polar and apolar regions of the protein surface. Finally, the structure of per-deuterated myoglobin has been refined using all reflections to a R factor of 17%

The total neutron cross-section of Nb at different temperatures for neutrons with energies below 1 eV

International Nuclear Information System (INIS)

Adib, M.; Abdel-Kawy, A.; Maayouf, R.M.A.; Fayek, M.; Mostafa, M.; Hamouda, I.

1981-09-01

Total neutron cross-section measurements have been performed for natural Nb at liquid nitrogen, room and 425 0 K temperatures in the energy range from 2 MeV - 1 eV. The measurements were performed using two time-of-flight spectrometers installed in front of two of the ET-RR-1 reactor horizontal channels. The neutron diffraction pattern of Nb, at room temperature, was obtained using a double axis crystal spectrometer installed also at the ET-RR-1 reactor. The obtained total neutron cross-sections were analyzed using the single level Breit-Wigner formula. The coherent scattering amplitude was determined from the Bragg reflections observed in the total neutron cross-section of Nb and the analysis of its neutron diffraction pattern. The incoherent and thermal inelastic scattering cross-sections of Nb were determined from the analysis of the total cross-section of Nb beyond the cut-off wavelength. The following results have been obtained: sigmasub(t) = (6.30+-0.20)b; sigmasub(coh) = (6.0+-0.3)b; sigmasub(incoh) = (2.0+-1.0)b; bsub(coh) = (6.91+-0.08)fm

Acoustic Holography With Incoherent Sources

NARCIS (Netherlands)

Druyvesteyn, W.F.; Raangs, R.

2005-01-01

In near field acoustic holography the sound field is scanned near the surface of the vibrating object; from these measurements the vibration of the structure can be calculated. In the case of correlated sources one reference signal is sufficient. When incoherent sources are present the separation of

Scintillating fibre tracking neutron detector

International Nuclear Information System (INIS)

Karlsson, Joakim.

1995-04-01

A detector for measurements of collimated fluxes of neutrons in the energy range 2-20 MeV is proposed. It utilizes (n.p) elastic scattering in scintillating optical fibres placed in successive orthogonal layers perpendicular to the neutron flux. A test module has been designed, constructed and tested with respect to separation of neutron and gamma events. The pulse height measurements show the feasibility to discriminate between neutron, gamma and background events. Application to measurements of fusion neutrons is considered. 18 refs, 22 figs, 4 tabs

Methods of neutron spectrometry

International Nuclear Information System (INIS)

Doerschel, B.

1981-01-01

The different methods of neutron spectrometry are based on the direct measurement of neutron velocity or on the use of suitable energy-dependent interaction processes. In the latter case the measuring effect of a detector is connected with the searched neutron spectrum by an integral equation. The solution needs suitable unfolding procedures. The most important methods of neutron spectrometry are the time-of-flight method, the crystal spectrometry, the neutron spectrometry by use of elastic collisions with hydrogen nuclei, and neutron spectrometry with the aid of nuclear reactions, especially of the neutron-induced activation. The advantages and disadvantages of these methods are contrasted considering the resolution, the measurable energy range, the sensitivity, and the experimental and computational efforts. (author)

Some elementary viewpoints on the recording and analysis of angular distributions in experimental fast neutron elastic scattering

International Nuclear Information System (INIS)

Wiedling, T.

1980-01-01

Total neutron elastic scattering cross-sections are usually estimated from the angular distributions of the differential cross sections. This circumstance makes some demands on the quality of the collection and evaluation of experimental differential cross-section data. In the present paper some problems associated with such measurements and effects which influence the analytical descriptions of the observations are discussed. Part of the paper is concerned with the problem of the proper fitting of a Legendre polynomial expansion to an experimental distribution which can only be recorded in a limited angular interval because of the geometrical dimensions of the shielding of a huge neutron detector. The effects of small angular shifts of some data points in the forward direction of angular distribution are discussed in some specific cases, namely for 209 Bi and 208 Pb at 8.05 and 25.7 MeV, respectively. Such shifts may be associated with a false position of the zero angle of the detector. A method is proposed for calibrating the zero-angle direction of the detector and some experimental results are reported. (orig.)

Neutron energy spectrum in graphite blankets of fusion reactors

International Nuclear Information System (INIS)

Tsechanski, A.

1981-09-01

Neutron flux measurements were performed in a graphite stack and compared with calculations made with a two dimensional transport computer code. In the present work it is observed that the calculated spectrum in the elastic and inelastic scattering ranges (the first collision range in both cases), is sensitive to details of the angular distribution of these neutrons. Regarding the discrepancies in the elastic scattering range it is concluded that the microscopic cross section library ENDF/B-IV overestimates the large angle scattering (back scattering) as can be seen from comparison of measured and calculated spectra. The two most important conclusions of the present work are: 1. Inelastic scattering interaction of D-T neutrons in graphite cannot be calculated without a proper account of energy-angle correlation. 2. An experimental setup supplying monoenergetic collimated D-T neutrons constitutes a sensitive although indirect means for measuring angular distributions in inelastic and elastic scattering

Boron nitride elastic and thermal properties. Irradiation effects

International Nuclear Information System (INIS)

Jager, Bernard.

1977-01-01

The anisotropy of boron nitride (BN) and especially thermal and elastic properties were studied. Specific heat and thermal conductivity between 1.2 and 300K, thermal conductivity between 4 and 350K and elastic constants C 33 and C 44 were measured. BN was irradiated with electrons at 77K and with neutrons at 27K to determine properties after irradiation [fr

Incoherent transport for phases that spontaneously break translations

Science.gov (United States)

Donos, Aristomenis; Gauntlett, Jerome P.; Griffin, Tom; Ziogas, Vaios

2018-04-01

We consider phases of matter at finite charge density which spontaneously break spatial translations. Without taking a hydrodynamic limit we identify a boost invariant incoherent current operator. We also derive expressions for the small frequency behaviour of the thermoelectric conductivities generalising those that have been derived in a translationally invariant context. Within holographic constructions we show that the DC conductivity for the incoherent current can be obtained from a solution to a Stokes flow for an auxiliary fluid on the black hole horizon combined with specific thermodynamic quantities associated with the equilibrium black hole solutions.

Symmetry effects in neutron scattering from isotopically enriched Se isotopes

Energy Technology Data Exchange (ETDEWEB)

Lachkar, J.; Haouat, G.; McEllistrem, M. T.; Patin, Y.; Sigaud, J.; Cocu, F.

1975-06-01

Differential cross sections for neutron elastic and inelastic scattering from {sup 76}Se, {sup 78}Se, {sup 80}Se and {sup 82}Se, have been measured at 8-MeV incident neutron energy and from {sup 76}Se and {sup 82}Se at 6- and 10-MeV incident energies. The differences observed in the elastic scattering cross sections are interpretable as the effects of isospin term in the scattering potentials. A full analysis of the elastic scattering data are presented.

Single-shot self-interference incoherent digital holography using off-axis configuration.

Science.gov (United States)

Hong, Jisoo; Kim, Myung K

2013-12-01

We propose a single-shot incoherent holographic imaging technique that adopts self-interference incoherent digital holography (SIDH) with slight tilt of the plane mirror in the optical configuration. The limited temporal coherence length of the illumination leads the guide-star hologram of the proposed system to have a Gaussian envelope of elliptical ring shape. The observation shows that the reconstruction by cross correlation with the guide-star hologram achieves better quality than the usual propagation methods. Experimentally, we verify that the hologram and 3D reconstruction can be implemented incoherently with the proposed single-shot off-axis SIDH.

On the theory of ultracold neutrons scattering by Davydov solitons

International Nuclear Information System (INIS)

Brizhik, L.S.

1984-01-01

Elastic coherent scattering of ultracold neutrons by Davydov solitons in one-dimensional periodic molecular chains without account of thermal oscillations of chain atoms is studied. It is shown that the expression for the differential cross section of the elastic neutron scattering by Davydov soliton breaks down into two components. One of them corresponds to scattering by a resting soliton, the other is proportional to the soliton velocity and has a sharp maximum in the direction of mirror reflection of neutrons from the chain

Neutron energy measurement for practical applications

Science.gov (United States)

Roshan, M. V.; Sadeghi, H.; Ghasabian, M.; Mazandarani, A.

2018-03-01

Industrial demand for neutrons constrains careful energy measurements. Elastic scattering of monoenergetic α -particles from neutron collision enables neutron energy measurement by calculating the amount of deviation from the position where collision takes place. The neutron numbers with specific energy is obtained by counting the number of α -particles in the corresponding location on the charged particle detector. Monte Carlo simulation and COMSOL Multiphysics5.2 are used to account for one-to-one collision of neutrons with α -particles.

Quasi-elastic neutron scattering studies of the slow dynamics of supercooled and glassy aspirin

International Nuclear Information System (INIS)

Zhang Yang; Mamontov, Eugene; Tyagi, Madhusudan; Chen, Sow-Hsin

2012-01-01

Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent β(Q) is independent of the wavevector transfer Q in the measured Q range and (ii) the structural relaxation time τ(Q) follows a power-law dependence on Q. Consequently, the Q-independent structural relaxation time τ 0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of τ 0 can be fitted with the mode-coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by Tokuyama in the measured temperature range. The calculated dynamic response function χ T (Q, t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement (x 2 ) and the non-Gaussian parameter α 2 extracted from the elastic scattering.

Quasi-elastic neutron scattering studies of the slow dynamics of supercooled and glassy aspirin

Science.gov (United States)

Zhang, Yang; Tyagi, Madhusudan; Mamontov, Eugene; Chen, Sow-Hsin

2012-02-01

Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent β(Q) is independent of the wavevector transfer Q in the measured Q range and (ii) the structural relaxation time τ(Q) follows a power-law dependence on Q. Consequently, the Q-independent structural relaxation time τ0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of τ0 can be fitted with the mode-coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by Tokuyama in the measured temperature range. The calculated dynamic response function χT(Q, t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement langx2rang and the non-Gaussian parameter α2 extracted from the elastic scattering.

Study of the performance of collision short time approximation for neutron scattering using discrete frequency distribution

International Nuclear Information System (INIS)

D'Oliveira, A.B.; Amorim, E.S. do; Galvao, O.B.

1981-03-01

Double differential cross sections for thermal neutrons, based on incoherent approximation, using continum distribution as discrete frequency set are theoretically estimated, regarding two models previously done. The FASTT computer program is used in order to obtain a numerical estimation. (L.C.) [pt

Neutron scattering studies in the actinide region

International Nuclear Information System (INIS)

Beghian, L.E.; Kegel, G.H.R.

1991-08-01

During the report period we have investigated the following areas: Neutron elastic and inelastic scattering measurements on 14 N, 181 Ta, 232 Th, 238 U and 239 Pu; Prompt fission spectra for 232 Th, 235 U, 238 U and 239 Pu; Theoretical studies of neutron scattering; Neutron filters; New detector systems; and Upgrading of neutron target assembly, data acquisition system, and accelerator/beam-line apparatus

The prediction of Neutron Elastic Scattering from Tritium for E(n) = 6-14 MeV

International Nuclear Information System (INIS)

Anderson, J.D.; Dietrich, F.S.; Luu, T.; McNabb, D.P.; Navratil, P.; Quaglioni, S.

2010-01-01

In a recent report Navratil et al. evaluated the angle-integrated cross section and the angular distribution for 14-MeV n+T elastic scattering by inferring these cross sections from accurately measured p+3He angular distributions. This evaluation used a combination of two theoretical treatments, based on the no-core shell model and resonating-group method (NCSM/RGM) and on the R-matrix formalism, to connect the two charge-symmetric reactions n+T and p+ 3 He. In this report we extend this treatment to cover the neutron incident energy range 6-14 MeV. To do this, we evaluate angle-dependent correction factors for the NCSM/RGM calculations so that they agree with the p+ 3 He data near 6 MeV, and using the results found earlier near 14 MeV we interpolate these correction factors to obtain correction factors throughout the 6-14 MeV energy range. The agreement between the corrected NCSM/RGM and R-Matrix values for the integral elastic cross sections is excellent (±1%), and these are in very good agreement with total cross section experiments. This result can be attributed to the nearly constant correction factors at forward angles, and to the evidently satisfactory physics content of the two calculations. The difference in angular shape, obtained by comparing values of the scattering probability distribution P(μ) vs. μ(the cosine of the c.m. scattering angle), is about ±4% and appears to be related to differences in the two theoretical calculations. Averaging the calculations yields P(μ) values with errors of ±2 1/2 % or less. These averaged values, along with the corresponding quantities for the differential cross sections, will form the basis of a new evaluation of n+T elastic scattering. Computer files of the results discussed in this report will be supplied upon request.

The prediction of Neutron Elastic Scattering from Tritium for E(n) = 6-14 MeV

Energy Technology Data Exchange (ETDEWEB)

Anderson, J D; Dietrich, F S; Luu, T; McNabb, D P; Navratil, P; Quaglioni, S

2010-06-14

In a recent report Navratil et al. evaluated the angle-integrated cross section and the angular distribution for 14-MeV n+T elastic scattering by inferring these cross sections from accurately measured p+3He angular distributions. This evaluation used a combination of two theoretical treatments, based on the no-core shell model and resonating-group method (NCSM/RGM) and on the R-matrix formalism, to connect the two charge-symmetric reactions n+T and p+{sup 3}He. In this report we extend this treatment to cover the neutron incident energy range 6-14 MeV. To do this, we evaluate angle-dependent correction factors for the NCSM/RGM calculations so that they agree with the p+{sup 3}He data near 6 MeV, and using the results found earlier near 14 MeV we interpolate these correction factors to obtain correction factors throughout the 6-14 MeV energy range. The agreement between the corrected NCSM/RGM and R-Matrix values for the integral elastic cross sections is excellent ({+-}1%), and these are in very good agreement with total cross section experiments. This result can be attributed to the nearly constant correction factors at forward angles, and to the evidently satisfactory physics content of the two calculations. The difference in angular shape, obtained by comparing values of the scattering probability distribution P({mu}) vs. {mu}(the cosine of the c.m. scattering angle), is about {+-}4% and appears to be related to differences in the two theoretical calculations. Averaging the calculations yields P({mu}) values with errors of {+-}2 1/2 % or less. These averaged values, along with the corresponding quantities for the differential cross sections, will form the basis of a new evaluation of n+T elastic scattering. Computer files of the results discussed in this report will be supplied upon request.

Harmonic-anharmonic transition in disaccharides/H{sub 2}O mixtures by EINS

Energy Technology Data Exchange (ETDEWEB)

Magazu, S.; Migliardo, F.; Mondelli, C

2004-07-15

This work furnishes new experimental findings on glass-forming systems, i.e. homologues disaccharides (trehalose, maltose, sucrose)/H{sub 2}O mixtures obtained by using elastic incoherent neutron scattering. Such a technique allows to characterize the different degree of 'strength' of the investigated systems by means of the analysis of both the elastic intensity and the mean square displacement behaviours as a function of temperature and Q. The better cryptoprotectant effectiveness of trehalose in comparison with the other disaccharides is ascribed to lower fragility of the matrix in which biostructures are immersed, i.e. of the trehalose/water mixture.

Polarized Elastic Fast-Neutron Scattering off {sup 12}C in the Lower MeV-Range. I. Experimental Part

Energy Technology Data Exchange (ETDEWEB)

Aspelund, O

1967-05-15

Practical as well as more fundamental interest in low-energy n-{sup 12}C elastic scattering motivated the execution of comprehensive polarization studies between 1.062 and 2.243 MeV. Seven complete polarization angular distributions were obtained from experimental finite-geometry left-right ratios at each energy observed at six or seven laboratory scattering angles between 30 and 129 deg, using polarized fast-neutrons emitted at {theta}{sub i} 50 (lab. syst.) from the {sup 7}Li(p, n) {sup 7}Be-reaction. Proper corrections were applied for finite geometry and polarized multiple-scattering effects as well as for the presence of the first-excited state group of fast-neutrons in the incident beams. The magnitude of the polarization effects are sufficiently large to ensure the potentialities of {sup 12}C as an acceptable fast-neutron polarization analyser in the energy range under consideration. Furthermore, on the basis of the above-mentioned polarization data as well as on the basis of total and differential scattering cross section data available in current literature reliable phase shifts were determined. These phase shifts are only in partial agreement with the ones of Wills, Jr. et al. , and in definite disagreement with the extrapolated phases of Meier, Scherrer, and Trumpy. Their energy variations will be predicted in the theoretical part of this contribution.

Determination of superstructures and magnetic structures in the system (Fe,Mn)(Nb,Ta)2O6 with elastic neutron scattering experiments

International Nuclear Information System (INIS)

Klein, S.

1976-01-01

The aim of this work was to study the magnetic structures of the Trirutil FeTa 2 O 6 and the Columbit MnTa 2 O 6 . A further question was the influence of the nonmagnetic positive Ions on the developing magnetic structure. One example is the mixed-crystal series Mn(Nb,Ta) 2 O 6 . The different magnetic structures of FeNb 2 O 6 and MnNb 2 O 6 , having the same chemical structure, causes the existence of a transition region between these two magnetic structures. Neutron diffration is a well-suited method to investigate the character of these concentration-dependent phase tansitions. All experiments have been performed with elastic neutrons, and a new set-up for measurrement of low temperatures has been used. For the evaluaion of these data two computer programs are developed. (orig./HPOE) [de

Ambiguities in the elastic scattering of 8 MeV neutrons from adjacent nuclei

International Nuclear Information System (INIS)

Smith, A.B.; Lawson, R.D.; Guenther, P.T.

1989-10-01

Ratios of the cross sections for elastic scattering of 8 MeV neutrons from adjacent nuclei are measured over the angular range ∼20 degree - 160 degree for the target pairs 51 V/Cr, 59 Co/ 58 Ni, Cu/Zn, 89 Y/ 93 Nb, 89 Y/Zr, 93 Nb/Zr, In/Cd and 209 Bi/Pb. The observed ratios vary from unity by as much as a factor of ∼2 at some angles for the lighter target pairs. Approximately half the measured ratios are reasonably explained by a simple spherical optical model, including size and isospin contributions. In all cases, the geometry of the real optical--model potential is essentially the same for neighboring nuclei, and the real--potential strengths are consistent with the Lane model. In contrast, it is found that the imaginary potential may be quite different for adjacent nuclei, and the nature of this difference is examined. It is shown that the spin--spin interaction has a negligible effect on the calculation of the elastic--scattering ratios, but that channel coupling, leading to a large reorientation of the target ground state, can be a consideration, particularly in the 59 Co/ 58 Ni case. In the A ∼ 50--60 region the calculated ratios are sensitive to spin--orbit effects, but the exact nature of this interaction must await more definitive polarization measurements. The measured and calculated results suggest that the concept of a conventional ''global'' or even ''regional'' optical potential provides no more than a qualitative representation of the physical reality for a number of cases. 48 refs., 14 figs., 3 tabs

The differential cross section and polarization for the elastic scattering of 2.9 MeV neutrons by Fe, Cu, I, Hg and Pb

International Nuclear Information System (INIS)

Galloway, R.B.; Waheed, A.

1979-01-01

Simultaneous measurements are presented of the angular dependence of polarization due to elastic scattering and of the elastic differential cross section for 2.9 MeV neutrons. The angular range covered is 20 0 to 160 0 for samples of Fe, Cu, I, Hg and Pb. The measurements are compared with the results of combining optical model and Hauser-Feshbach calculations. The optical model calculations were performed using 'global fit' parameters as well as with parameters suggested previously for the particular nuclei. The Hauser-Feshbach calculations were performed both with and without the level width fluctuation correction. It is clear that the calculations made without the level width fluctuation correction provide a better fit to the data for Fe, Cu, I and Hg and only for Pb does inclusion of the level width fluctuation correction provide a better fit. These optical model parameter sets are shown not to be very successful in fitting both differential cross-section and polarization data. The results of searches for the parameters which give the best fit for the data are presented. These parameter sets are compared with one another and with the results of 8 and 11 MeV neutron scattering studies for trends in the variation of the parameters. (Auth.)

Application of quasi-elastic neutron scattering to dynamics study of confined water

International Nuclear Information System (INIS)

Li Hua; Zhang Lili; Yi Zhou

2014-01-01

Background: Quasi-elastic neutron scattering (QENS) is an important experiment for dynamics study of confined water. It is significant to study the dynamics of confined water in cement paste. Purpose: In this paper, we have two aims. One is to present a reviewer of QENS study on dynamics of confined water in cement paste in recent years. The other is to illustrate the QENS application to the study on dynamics of confined water based on cement paste. Method: Relaxing cage model (RCM) is specially introduced for the analyses of QENS spectra. Results: Based on RCM, several parameters for describing the dynamics of confined water in cement paste, can be obtained from the analyses of QENS spectra: a fraction of mobile 'glassy' water molecules embedded in amorphous gel region surrounding the hydration products, 1-p, the capture time of confined water molecule in some place-τ 0 , the average translational relaxation time-<τ>, the self-diffusion coefficient-D, and a phenomenological shape parameter describing the uniform of amorphous in cement paste-β. Conclusion: All these provide a practical method for QENS study on dynamics of confined water in cement paste. (authors)

Coherent and incoherent (μ-, e-) conversion in nuclei

International Nuclear Information System (INIS)

Chiang, H.C.; Oset, E.; Kosmas, T.S.; Faessler, A.; Vergados, J.D.

1993-01-01

Coherent and incoherent (μ - , e - ) conversion in nuclei is studied within the framework of several theories which violate flavour lepton number. A useful approach is followed which allows a factorization of the conversion widths into nuclear factors and other factors which depend only on the elementary process. The nuclear factors are evaluated in a wide range of nuclei allowing simple calculations of the conversion rates throughout the periodic table for a given theory with a minimum of work in the elementary sector. The coherent conversion is found to dominate the process. The results obtained modify appreciable previous results in the literature, particularly in the incoherent process. (orig.)

Quasielastic neutron scattering facility at Dhruva reactor

International Nuclear Information System (INIS)

Mukhopadhyay, R.; Mitra, S.; Paranjpe, S.K.; Dasannacharya, B.A.

2001-01-01

Quasi-elastic neutron scattering is a powerful experimental tool for studying the various dynamical motions in solids and liquids. In this paper, we have described the salient features of the quasi-elastic neutron spectrometer in operation at Dhruva reactor at Trombay, India. The design criteria have been such as to maximise the throughput by various means like closer approach to the source, focusing a larger beam on to a sample, and Multi-Angle Reflecting X-tal mode of energy analysis. Some results of molecular motions from recently studied systems using this spectrometer are also reported

Mean square hydrogen fluctuations in chitosan/lecithin nanoparticles from elastic neutron scattering experiments

Science.gov (United States)

Sonvico, Fabio; Teresa Di Bari, Maria; Bove, Livia; Deriu, Antonio; Cavatorta, Fabrizio; Albanese, Gianfranco

2006-11-01

Recently, we have started a systematic study of the structure and dynamics of nano- and microparticles of interest as highly biocompatible drug carriers. For these particles, that are composed of polymeric and lipid material, a detailed understanding of the particle-solvent interactions is of key importance in order to tailor their characteristics for delivering drugs with specific chemical properties. Here we report results of elastic neutron scattering (ENS) investigations on lecithin/chitosan nanoparticles. They were first prepared by autoassembling the two components in aqueous solution; the samples were then freeze-dried and re-hydrated in a D 2O atmosphere. The experiments were performed in the temperature range of 20-50 K using the backscattering spectrometer IN13 at ILL (Grenoble, France). The comparison of samples in the dry state with similar ones at an hydration level of about 0.3-0.4 (g D 2O/g hydrated sample), indicates that the presence of an outer chitosan ‘‘coating’’ reduces the mean square fluctuations of the hydrogens in the lipid component, leading thus to a stiffer nanoparticle structure.

A mercury programme (autocode programme 5675) for transforming data on the angular distribution of elastically scattered neutrons to one standard form

International Nuclear Information System (INIS)

King, D.C.

1964-04-01

Data on the angular distribution of elastically scattered neutrons are reported in one or another of a variety of different forms. The Mercury autocode programme 5675 transforms the data into a tabular representation of the form (cosθ, p (cosθ)) where p(cosθ) is the normalised probability distribution and θ is the scattering angle in the centre of mass frame of reference. Output on cards punched in the format of the U.K.A.E.A. nuclear data library is optional. (author)

Neutron scattering equipments in JAERI. Current status

International Nuclear Information System (INIS)

Hamaguchi, Yoshikazu; Minakawa, Nobuaki

2003-01-01

24 neutron scattering instruments are installed in the JRR-3M research reactor. Among them JAERI has 12 neutron scattering instruments. Those instruments are HRPD for high-resolution structural analysis, TAS-1 and TAS-2 for elastic and inelastic scattering and for magnetic scattering measurements by the polarized neutron, LTAS for elastic and inelastic scattering measurement at a low energy region, and for neutron device development, PNO for topography and for very small angle scattering measurement in a small Q range, NRG for neutron radiography, RESA for internal strain measurements, SANS for the molecule and semi-macroscopic magnetic structural analysis, BIX-2 and BIX-3 for the biological structural analysis research, and PGA for the research of prompt gamma-ray analysis. The university groups have 12 neutron scattering instruments. Since those instruments were installed at the period when JRR-3M was completed, about 10 years have passed. In order to match the old control systems with the progress of recent computer technologies, and peripheral equipment, numbers of instruments are being renewed. In the neutron guide hall of JRR-3M, the Ni mirror guide tube was replaced by a super mirror guide tube to increase neutron flux. The intensity of 2A flux was increased by a factor of about two. (J.P.N.)

The Dynamics and Structures of Adsorbed Surfaces

DEFF Research Database (Denmark)

Nielsen, M; Ellenson, W. D.; McTague, J. P.

1978-01-01

. Elastic neutron diffraction measurements, determining the two-dimensional structural ordering of the adsorbed films, have been performed on layers of N2, Ar, H2, D2, O2, Kr, and He. Measurements on layers of larger molecules such as CD4 and ND3 have also been reported. Inelastic neutron scattering...... measurements, studying the dynamics of the adsorbed films are only possible in a few especially favourable cases such as 36Ar and D2 films, where the coherent phonon scattering cross-sections are very large. In other cases incoherent scattering from hydrogen can give information about e.g. the mobility...

Contrasting dynamics of fragile and non-fragile polyalcohols through the glass, and dynamical, transitions: A comparison of neutron scattering and dielectric relaxation data for sorbitol and glycerol.

Science.gov (United States)

Migliardo, F; Angell, C A; Magazù, S

2017-01-01

Glycerol and sorbitol are glass-forming hydrogen-bonded systems characterized by intriguing properties which make these systems very interesting also from the applications point of view. The goal of this work is to relate the hydrogen-bonded features, relaxation dynamics, glass transition properties and fragility of these systems, in particular to seek insight into their very different liquid fragilities. The comparison between glycerol and sorbitol is carried out by collecting the elastic incoherent neutron scattering (EINS) intensity as a function of temperature and of the instrumental energy resolution. Intensity data vs temperature and resolution are analyzed in terms of thermal restraint and Resolution Elastic Neutron Scattering (RENS) approaches. The number of OH groups, which are related to the connecting sites, is a significant parameter both in the glass transition and in the dynamical transition. On the other hand, the disordered nature of sorbitol is confirmed by the existence of different relaxation processes. From the applications point of view, glycerol and sorbitol have remarkable bioprotectant properties which make these systems useful in different technological and industrial fields. Furthermore, polyols are rich in glassforming liquid phenomenology and highly deserving of study in their own right. The comparison of EINS and calorimetric data on glycerol and sorbitol helps provide a connection between structural relaxation, dynamical transition, glass transition, and fragility. The evaluation of the inflection point in the elastic intensity behavior as a function of temperature and instrumental energy resolution provides a confirmation of the validity of the RENS approach. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo. Copyright © 2016. Published by Elsevier B.V.

Addressing preservation of elastic contrast in energy-filtered transmission electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Brown, H.G.; D' Alfonso, A.J.; Forbes, B.D.; Allen, L.J., E-mail: lja@unimelb.edu.au

2016-01-15

Energy-filtered transmission electron microscopy (EFTEM) images with resolutions of the order of an Ångström can be obtained using modern microscopes corrected for chromatic aberration. However, the delocalized nature of the transition potentials for atomic ionization often confounds direct interpretation of EFTEM images, leading to what is known as “preservation of elastic contrast”. In this paper we demonstrate how more interpretable images might be obtained by scanning with a focused coherent probe and incoherently averaging the energy-filtered images over probe position. We dub this new imaging technique energy-filtered imaging scanning transmission electron microscopy (EFISTEM). We develop a theoretical framework for EFISTEM and show that it is in fact equivalent to precession EFTEM, where the plane wave illumination is precessed through a range of tilts spanning the same range of angles as the probe forming aperture in EFISTEM. It is demonstrated that EFISTEM delivers similar results to scanning transmission electron microscopy with an electron energy-loss spectrometer but has the advantage that it is immune to coherent aberrations and spatial incoherence of the probe and is also more resilient to scan distortions. - Highlights: • Interpretation of EFTEM images is complicated by preservation of elastic contrast. • More direct images obtained by scanning with a focused coherent probe and averaging. • This is equivalent to precession EFTEM through the solid angle defined by the probe. • Also yields similar results to energy-loss scanning transmission electron microscopy. • Scanning approach immune to probe aberrations and resilient to scan distortions.

Neutron scattering cross sections of uranium-238

International Nuclear Information System (INIS)

Beghian, L.E.; Kegel, G.H.R.; Marcella, T.V.; Barnes, B.K.; Couchell, G.P.; Egan, J.J.; Mittler, A.; Pullen, D.J.; Schier, W.A.

1979-01-01

The University of Lowell high-resolution time-of-flight spectrometer was used to measure angular distributions and 90-deg excitation functions for neutrons scattered from 238 U in the energy range from 0.9 to 3.1 MeV. This study was limited to the elastic and the first two inelastic groups, corresponding to states of 238 U at 45 keV (2 + ) and 148 keV (4 + ). Angular distributions were measured at primary neutron energies of 1.1, 1.9, 2.5, and 3.1 MeV for the same three neutron groups. Whereas the elastic data are in fair agreement with the evaluation in the ENDF/B-IV file, there is substantial disagreement between the inelastic measurements and the evaluated cross sections. 12 figures

Polarized-neutron study of spin dynamics in the Kondo insulator YbB12.

Science.gov (United States)

Nemkovski, K S; Mignot, J-M; Alekseev, P A; Ivanov, A S; Nefeodova, E V; Rybina, A V; Regnault, L-P; Iga, F; Takabatake, T

2007-09-28

Inelastic neutron scattering experiments have been performed on the archetype compound YbB(12), using neutron polarization analysis to separate the magnetic signal from the phonon background. With decreasing temperature, components characteristic for a single-site spin-fluctuation dynamics are suppressed, giving place to specific, strongly Q-dependent, low-energy excitations near the spin-gap edge. This crossover is discussed in terms of a simple crystal-field description of the incoherent high-temperature state and a predominantly local mechanism for the formation of the low-temperature singlet ground state.

Three dimensional winds: A maximum cross-correlation application to elastic lidar data

Energy Technology Data Exchange (ETDEWEB)

Buttler, William Tillman [Univ. of Texas, Austin, TX (United States)

1996-05-01

Maximum cross-correlation techniques have been used with satellite data to estimate winds and sea surface velocities for several years. Los Alamos National Laboratory (LANL) is currently using a variation of the basic maximum cross-correlation technique, coupled with a deterministic application of a vector median filter, to measure transverse winds as a function of range and altitude from incoherent elastic backscatter lidar (light detection and ranging) data taken throughout large volumes within the atmospheric boundary layer. Hourly representations of three-dimensional wind fields, derived from elastic lidar data taken during an air-quality study performed in a region of complex terrain near Sunland Park, New Mexico, are presented and compared with results from an Environmental Protection Agency (EPA) approved laser doppler velocimeter. The wind fields showed persistent large scale eddies as well as general terrain-following winds in the Rio Grande valley.

Polarized neutron powder diffraction studies of antiferromagnetic order in bulk and nanoparticle NiO

DEFF Research Database (Denmark)

Brok, Erik; Lefmann, Kim; Deen, Pascale P.

2015-01-01

surface contribution to the magnetic anisotropy. Here we explore the potential use of polarized neutron diffraction to reveal the magnetic structure in NiO bulk and nanoparticle powders by applying the XYZ-polarization analysis method. Our investigations address in particular the spin orientation in bulk....... The results show that polarization analyzed neutron powder diffraction is a viable method to investigate magnetic order in powders of antiferromagnetic nanoparticles.......In many materials it remains a challenge to reveal the nature of magnetic correlations, including antiferromagnetism and spin disorder. Revealing the spin structure in magnetic nanoparticles is further complicated by the large incoherent neutron scattering cross section from water adsorbed...

Generalized synthetic kernel approximation for elastic moderation of fast neutrons

International Nuclear Information System (INIS)

Yamamoto, Koji; Sekiya, Tamotsu; Yamamura, Yasunori.

1975-01-01

A method of synthetic kernel approximation is examined in some detail with a view to simplifying the treatment of the elastic moderation of fast neutrons. A sequence of unified kernel (fsub(N)) is introduced, which is then divided into two subsequences (Wsub(n)) and (Gsub(n)) according to whether N is odd (Wsub(n)=fsub(2n-1), n=1,2, ...) or even (Gsub(n)=fsub(2n), n=0,1, ...). The W 1 and G 1 kernels correspond to the usual Wigner and GG kernels, respectively, and the Wsub(n) and Gsub(n) kernels for n>=2 represent generalizations thereof. It is shown that the Wsub(n) kernel solution with a relatively small n (>=2) is superior on the whole to the Gsub(n) kernel solution for the same index n, while both converge to the exact values with increasing n. To evaluate the collision density numerically and rapidly, a simple recurrence formula is derived. In the asymptotic region (except near resonances), this recurrence formula allows calculation with a relatively coarse mesh width whenever hsub(a)<=0.05 at least. For calculations in the transient lethargy region, a mesh width of order epsilon/10 is small enough to evaluate the approximate collision density psisub(N) with an accuracy comparable to that obtained analytically. It is shown that, with the present method, an order of approximation of about n=7 should yield a practically correct solution diviating not more than 1% in collision density. (auth.)

Fragility of complexity biophysical systems by neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Magazu, Salvatore [Dipartimento di Fisica, Universita di Messina, P.O. Box 55, I-98166 Messina (Italy)]. E-mail: smagazu@unime.it; Migliardo, Federica [Dipartimento di Fisica, Universita di Messina, P.O. Box 55, I-98166 Messina (Italy); Bellocco, Ersilia [Dipartimento di Chimica Organica e Biologica, Universita di Messina, I-98166 Messina (Italy); Lagana, Giuseppina [Dipartimento di Chimica Organica e Biologica, Universita di Messina, I-98166 Messina (Italy); Mondelli, Claudia [CNR-INFM OGG and CRS-SOFT, c/o ILL, 6 Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France)

2006-11-15

Neutron scattering is an exceptional tool to investigate structural and dynamical properties of systems of biophysical interest, such as proteins, enzymes, lipids and sugars. Moreover, elastic neutron scattering enhances the investigation of atomic motions in hydrated proteins in a wide temperature range and on the picosecond timescale. Homologous disaccharides, such as trehalose, maltose and sucrose, are cryptobiotic substances, since they allow to many organisms to undergo in a 'suspended life' state, known as cryptobiosis in extreme environmental conditions. The present paper is aimed to discuss the fragility degree of disaccharides, as evaluated of the temperature dependence of the mean square displacement by elastic neutron scattering, in order to link this feature with their bioprotective functions.

Anomalous vibrational modes in acetanilide as studied by inelastic neutron scattering

Science.gov (United States)

Barthes, Mariette; Eckert, Juegen; Johnson, Susanna W.; Moret, Jacques; Swanson, Basil I.; Unkefer, Clifford J.

1992-10-01

A study of the anomalous modes in acetanilide and five deuterated derivatives by incoherent inelastic neutron scattering is reported. These data show that the dynamics of the amide and methyl groups influence each other. In addition, the anomalous temperature behaviour of the NH out-of-plane bending mode is confirmed. These observations suggest that the self-trapping mechanism in ACN may be more complex than hitherto assumed.

Transmission of germanium poly- and monocrystals for thermal neutrons at different temperatures

International Nuclear Information System (INIS)

Adib, M.; Abdel-Kawy, A.; Eid, Y.; Maayouf, R.M.; Abbas, Y.; Habib, N.; Kilany, M.; Ashry, A.

1987-01-01

Neutron cross-sections of germanium poly- and monocrystals were measured with two time-of-flight and two double-axis crystal spectrometers. The results were analyzed using the single-level Breit-Wigner formula. The coherent scattering amplitude was determined from the Bragg reflections observed in the cross-section of a polycrystal and the analysis of the neutron diffraction pattern. The incoherent and the thermal diffuse scattering cross-section were estimated from the analysis of the total cross-section data obtained for a monocrystal at different temperatures in the energy range 2 meV to 1 eV. (orig./HP) [de

Transmission of germanium poly- and monocrystals for thermal neutrons at different temperatures

Energy Technology Data Exchange (ETDEWEB)

Adib, M.; Abdel-Kawy, A.; Eid, Y.; Maayouf, R.M.; Abbas, Y.; Habib, N.; Kilany, M.; Ashry, A.

Neutron cross-sections of germanium poly- and monocrystals were measured with two time-of-flight and two double-axis crystal spectrometers. The results were analyzed using the single-level Breit-Wigner formula. The coherent scattering amplitude was determined from the Bragg reflections observed in the cross-section of a polycrystal and the analysis of the neutron diffraction pattern. The incoherent and the thermal diffuse scattering cross-section were estimated from the analysis of the total cross-section data obtained for a monocrystal at different temperatures in the energy range 2 meV to 1 eV.

On determination of the dynamics of hydrocarbon molecules on catalyst's surfaces by means of neutron scattering

International Nuclear Information System (INIS)

Stockmeyer, R.

1976-01-01

The intensity distribution of slow neutrons scattered by adsorbed hydrocarbon molecules contains information on the dynamics of the molecules. In this paper the scattering law for incoherently scattering molecules is derived taking into account the very different mobility perpendicular and parallel to the surface. In contrast to the well known scattering law of threedimensionally diffusing particles the scattering law for twodimensional diffusion diverges logarithmically at zero energy transfer. Conclusions relevant to the interpretation of neutron scattering data are discussed. (orig.) [de

Swelling in neutron irradiated nickel-base alloys

International Nuclear Information System (INIS)

Brager, H.R.; Bell, W.L.

1972-01-01

Inconel 625, Incoloy 800 and Hastelloy X were neutron irradiated at 500 to 700 0 C. It was found that of the three alloys investigated, Inconel 625 offers the greatest swelling resistance. The superior swelling resistance of Inconel 625 relative to that of Hastelloy-X is probably related to differences in the concentrations of the minor rather than major alloy constituents, and can involve (a) enhanced recombination of defects in the Inconel 625 and (b) preferential attraction of vacancies to incoherent precipitates. (U.S.)

Ambiguities in the elastic scattering of 8 MeV neutrons from adjacent nuclei

Energy Technology Data Exchange (ETDEWEB)

Smith, A.B.; Lawson, R.D.; Guenther, P.T.

1989-10-01

Ratios of the cross sections for elastic scattering of 8 MeV neutrons from adjacent nuclei are measured over the angular range {approx}20{degree} {minus} 160{degree} for the target pairs {sup 51}V/Cr, {sup 59}Co/{sup 58}Ni, Cu/Zn, {sup 89}Y/{sup 93}Nb, {sup 89}Y/Zr, {sup 93}Nb/Zr, In/Cd and {sup 209}Bi/Pb. The observed ratios vary from unity by as much as a factor of {approx}2 at some angles for the lighter target pairs. Approximately half the measured ratios are reasonably explained by a simple spherical optical model, including size and isospin contributions. In all cases, the geometry of the real optical--model potential is essentially the same for neighboring nuclei, and the real--potential strengths are consistent with the Lane model. In contrast, it is found that the imaginary potential may be quite different for adjacent nuclei, and the nature of this difference is examined. It is shown that the spin--spin interaction has a negligible effect on the calculation of the elastic--scattering ratios, but that channel coupling, leading to a large reorientation of the target ground state, can be a consideration, particularly in the {sup 59}Co/{sup 58}Ni case. In the A {approx} 50--60 region the calculated ratios are sensitive to spin--orbit effects, but the exact nature of this interaction must await more definitive polarization measurements. The measured and calculated results suggest that the concept of a conventional global'' or even regional'' optical potential provides no more than a qualitative representation of the physical reality for a number of cases. 48 refs., 14 figs., 3 tabs.

Incoherent quasielastic neutron scattering from water in supercooled regime

International Nuclear Information System (INIS)

Chen, S.; Teixeira, J.; Nicklow, R.

1982-01-01

Measurements of the quasielastic spectra have been made with a three-axis neutron spectrometer at constant-Q mode in a temperature range from 38 0 C down to -20 0 C. Two energy resolutions both high (δE = 100 μ eV) and low (δE = 800 μ eV) were used to identify and separate a sharp component from a broad one. As temperature is decreased below zero the spectrum shows an increasing sharp component standing out on top of the broad one. The broad component is attributed to rotational motions of water molecules. A preliminary analysis of the linewidths gives a Q-independent relaxation time which has the same magnitude as the rotational relaxation time measured by nuclear magnetic resonance. The Q dependence of the sharp line is analyzed by a Q-dependent diffusion coefficient. A temperature-independent characteristic length l 0 = 0.5 A is obtained. We then attempt to relate this length to local geometry of protons associated with hydrogen bonding

Incoherent imaging using dynamically scattered coherent electrons

International Nuclear Information System (INIS)

Nellist, P.D.; Pennycook, S.J.

1999-01-01

We use a Bloch wave approach to show that, even for coherent dynamical scattering from a stationary lattice with no absorption, annular dark-field imaging in a scanning transmission electron microscope gives a direct incoherent structure image of the atomic-column positions of a zone-axis-aligned crystal. Although many Bloch waves may be excited by the probe, the detector provides a filtering effect so that the 1s-type bound states are found to dominate the image contrast for typical experimental conditions. We also find that the column intensity is related to the transverse kinetic energy of the 1s states, which gives atomic number, Z, contrast. The additional effects of phonon scattering are discussed, in particular the reasons why phonon scattering is not a prerequisite for transverse incoherence. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Incoherences of Brazilian labour laws face to present radioprotection concepts

International Nuclear Information System (INIS)

Borges, J.C.

1996-01-01

The Brazilian labour legislation establishes, since 1950, some privileges for people working in activities which imply exposure to ionizing radiations. Comparing the present legal framework with technical radioprotection knowledge, one can detect several incoherences covering: classification of such activities; additional payments; reduced labour journey; more vacations; medical surveillance; early retirements; special norms for women. An analysis of these incoherences lead us to propose a new frame of labour rights and radioprotection norms, coupling Brazilian juridical principles and modern radioprotection knowledge. (author)

Incoherent SSI Analysis of Reactor Building using 2007 Hard-Rock Coherency Model

International Nuclear Information System (INIS)

Kang, Joo-Hyung; Lee, Sang-Hoon

2008-01-01

Many strong earthquake recordings show the response motions at building foundations to be less intense than the corresponding free-field motions. To account for these phenomena, the concept of spatial variation, or wave incoherence was introduced. Several approaches for its application to practical analysis and design as part of soil-structure interaction (SSI) effect have been developed. However, conventional wave incoherency models didn't reflect the characteristics of earthquake data from hard-rock site, and their application to the practical nuclear structures on the hard-rock sites was not justified sufficiently. This paper is focused on the response impact of hard-rock coherency model proposed in 2007 on the incoherent SSI analysis results of nuclear power plant (NPP) structure. A typical reactor building of pressurized water reactor (PWR) type NPP is modeled classified into surface and embedded foundations. The model is also assumed to be located on medium-hard rock and hard-rock sites. The SSI analysis results are obtained and compared in case of coherent and incoherent input motions. The structural responses considering rocking and torsion effects are also investigated

The analysis of the elastic scattering of 11Be and 6Li by adiabatic approximation

International Nuclear Information System (INIS)

Takagi, S.

2000-01-01

The unstable nuclei, particularly, the neutron halo nuclei which exist near by the neutron dripline, are recently one of the interesting topics in the nuclear physics. By the adiabatic approximation, R. C. Jhonson et al. have reproduced the experimental differential cross-section of the elastic scattering of the neutron halo nucleus 11 Be (+ l2 C) [1]. We have applied their method to the elastic scattering of another nucleus 6 Li which is not a halo nucleus but has the cluster structure as 11 Be. But it couldn't reproduce the experimental data, so that the method of Johnson et al. is poor in the case of 6 Li. (author)

Coherent vs Incoherent Emission from Semiconductor Structures after Resonant Femtosecond Excitation

Science.gov (United States)

Gurioli, Massimo; Bogani, Franco; Ceccherini, Simone; Colocci, Marcello

1997-04-01

We show that an interferometric correlation measurement with fs time resolution provides an unambiguous discrimination between coherent and incoherent emission after resonant femtosecond excitation. The experiment directly probes the most important difference between the two emissions, that is, the phase correlation with the excitation pulse. The comparison with cw frequency resolved measurements demonstrates that the relationship between coherent and incoherent emission is similar under femtosecond and steady-state excitation.

Effect of nanodiamond fluorination on the efficiency of quasispecular reflection of cold neutrons

Science.gov (United States)

Nesvizhevsky, V. V.; Dubois, M.; Gutfreund, Ph.; Lychagin, E. V.; Nezvanov, A. Yu.; Zhernenkov, K. N.

2018-02-01

Nanomaterials, which show large reflectivity for external radiation, are of general interest in science and technology. We report a result from our ongoing research on the reflection of low-energy neutrons from powders of detonation diamond nanoparticles. Our previous work showed a large probability for quasispecular reflection of neutrons from this medium. The model of neutron scattering from nanoparticles, which we have developed, suggests two ways to increase the quasispecular reflection probability: (1) the reduction of incoherent scattering by substitution of hydrogen with fluorine inside the nanoparticles, and (2) the sharpening of the neutron optical potential step by removal of amorphous s p2 carbon from the nanoparticle shells. We present experimental results on scattering of slow neutrons from both raw and fluorinated diamond nanoparticles with amorphous s p2 carbon removed by gas-solid fluorination. These results show a clear increase in quasispecular reflection probability.

Is the Precautionary Principle Really Incoherent?

Science.gov (United States)

Boyer-Kassem, Thomas

2017-11-01

The Precautionary Principle has been an increasingly important principle in international treaties since the 1980s. Through varying formulations, it states that when an activity can lead to a catastrophe for human health or the environment, measures should be taken to prevent it even if the cause-and-effect relationship is not fully established scientifically. The Precautionary Principle has been critically discussed from many sides. This article concentrates on a theoretical argument by Peterson (2006) according to which the Precautionary Principle is incoherent with other desiderata of rational decision making, and thus cannot be used as a decision rule that selects an action among several ones. I claim here that Peterson's argument fails to establish the incoherence of the Precautionary Principle, by attacking three of its premises. I argue (i) that Peterson's treatment of uncertainties lacks generality, (ii) that his Archimedian condition is problematic for incommensurability reasons, and (iii) that his explication of the Precautionary Principle is not adequate. This leads me to conjecture that the Precautionary Principle can be envisaged as a coherent decision rule, again. © 2017 Society for Risk Analysis.

Neutron Scattering Differential Cross Sections for 12C

Science.gov (United States)

Byrd, Stephen T.; Hicks, S. F.; Nickel, M. T.; Block, S. G.; Peters, E. E.; Ramirez, A. P. D.; Mukhopadhyay, S.; McEllistrem, M. T.; Yates, S. W.; Vanhoy, J. R.

2016-09-01

Because of the prevalence of its use in the nuclear energy industry and for our overall understanding of the interactions of neutrons with matter, accurately determining the effects of fast neutrons scattering from 12C is important. Previously measured 12C inelastic neutron scattering differential cross sections found in the National Nuclear Data Center (NNDC) show significant discrepancies (>30%). Seeking to resolve these discrepancies, neutron inelastic and elastic scattering differential cross sections for 12C were measured at the University of Kentucky Acceleratory Laboratory for incident neutron energies of 5.58, 5.83, and 6.04 MeV. Quasi mono-energetic neutrons were scattered off an enriched 12C target (>99.99%) and detected by a C6D6 liquid scintillation detector. Time-of-flight (TOF) techniques were used to determine scattered neutron energies and allowed for elastic/inelastic scattering distinction. Relative detector efficiencies were determined through direct measurements of neutrons produced by the 2H(d,n) and 3H(p,n) source reactions, and absolute normalization factors were found by comparing 1H scattering measurements to accepted NNDC values. This experimental procedure has been successfully used for prior neutron scattering measurements and seems well-suited to our current objective. Significant challenges were encountered, however, with measuring the neutron detector efficiency over the broad incident neutron energy range required for these measurements. Funding for this research was provided by the National Nuclear Security Administration (NNSA).

A New Apparatus for Inelastic, Quasi-Elastic and Elastic Cold Neutron Measurements; Un nouveau appareil pour les mesures de diffusion inelastique , quasi-elastique et elastique des neutrons lents; Novyj pribor dlya izmereniya neuprugogo, kvaziuprugogo i uprugogo rasseyaniya kholodnykh nejtrohov; Nuevo aparato para mediciones inelastic as, cuasi elasticas y elasticas de neutrones frios

Energy Technology Data Exchange (ETDEWEB)

Otnes, K; Palevsky, H [Brookhaven National Laboratory, Upton, NY (United States)

1963-01-15

A new chopper apparatus for use at the Brookhaven High Flux Beam Reactor is now under construction. It is a three-element phased rotof system. The rotors are 80 cm in diameter, run at a maximum speed of 15000 rev/min, and are designed to give three neutron bursts of monochromatic neutrons per revolution. Two rotors spin about a horizontal axis whereas the third operates vertically. The system can be operated with either one, two or three of the chopper elements, depending on the type of measurement that is completed. For inelastic measurements where the neutron gains energy, a double rotor system will be most useful. For this configuration the burst time and wave length spread (full widths at 1/2 maximum) will be 16 {mu}s and 0.16 A for 4 A incident neutrons, and the intensity at the sample (4 x 1.6 cm) will be 2 x 10{sup 6} n/s. For quasi-elastic and elastic neutron measurements the three-rotor configuration will be best suited. The corresponding burst time and wave length spread can be as small as 8 {mu}s and 0.04 A giving an intensity of 10{sup 4} n/s on a sample of (4 X 0.8 c m ), The wave length and time resolution are adjustable between the above two limits in such a way as to obtain the maximum neutron intensity for a given experiment. (author) [French] Un nouveau selecteur destine au reacteur a haut flux de Brookhaven est actuellement en construction. Il s'agit d'un dispositif a trois rotors dephasables. Les rotors ont un diametre de 80 cm, tournent a une vitesse maximum de 15 000 tours pat minute et sont concus de maniere a fournir trois bouffees de neutrons monochromatiques a chaque tour. Deux rotors tournent autour d'un axe horizontal, le troisieme, autour d'un axe vertical. Le dispositif peut fonctionner avec un, deux ou trois elements, selon le type de mesure que l'on se propose de faire. Pour les mesures de diffusion inelastique ou les neutrons gagnent de l'energie, un dispositif a deux rotors sera tres utile. Pour cette configuation, la duree et la

Neutrons in studies of phospholipid bilayers and bilayer–drug interaction. I. Basic principles and neutron diffraction

Directory of Open Access Journals (Sweden)

Belička M.

2014-12-01

Full Text Available In our paper, we demonstrate several possibilities of using neutrons in pharmaceutical research with the help of examples of scientific results achieved at our University. In this first part, basic properties of neutrons and elementary principles of elastic scattering of thermal neutrons are described. Results of contrast variation neutron diffraction on oriented phospholipid bilayers with intercalated local anaesthetic or cholesterol demonstrate the potential of this method at determination of their position in bilayers. Diffraction experiments with alkan-1-ols located in the bilayers revealed their influence on bilayer thickness as a function of their alkyl chain length.

SIMULATED 8 MeV NEUTRON RESPONSE FUNCTIONS OF A THIN SILICON NEUTRON SENSOR.

Science.gov (United States)

Takada, Masashi; Matsumoto, Tetsuro; Masuda, Akihiko; Nunomiya, Tomoya; Aoyama, Kei; Nakamura, Takashi

2017-12-22

Neutron response functions of a thin silicon neutron sensor are simulated using PHITS2 and MCNP6 codes for an 8 MeV neutron beam at angles of incidence of 0°, 30° and 60°. The contributions of alpha particles created from the 28Si(n,α)25Mg reaction and the silicon nuclei scattered elastically by neutrons in the silicon sensor have not been well reproduced using the MCNP6 code. The 8 MeV neutron response functions simulated using the PHITS2 code with an accurate event generator mode are in good agreement with experimental results and include the contributions of the alpha particles and silicon nuclei. © The Author(s) 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Accelerator-based pulsed cold neutron source

International Nuclear Information System (INIS)

Inoue, Kazuhiko; Iwasa, Hirokatsu; Kiyanagi, Yoshiaki

1979-01-01

An accelerator-based pulsed cold neutron source was constructed. The accelerator is a 35 MeV electron linear accelerator with 1 kW average beam power. The cold neutron beam intensity at a specimen is equivalent to that of a research reactor of 10 14 n/cm 2 .s thermal flux in the case of the quasi-elastic neutron scattering measurements. In spite of some limitations to the universal uses, it has been demonstrated by this facility that the modest capacity accelerator-based pulsed cold neutron source is a highly efficient cold neutron source with low capital investment. Design philosophy, construction details, performance and some operational experiences are described. (author)

Study of proton-induced reactions and correlation with fast-neutron scattering

International Nuclear Information System (INIS)

Hansen, L.F.

1982-01-01

The generation of cross sections for fast neutron-nucleon interactions obtained from elastic and charge-exchange proton data is discussed in terms of the Lane model formalism. A general description of the interaction of nucleons with nuclei is presented in terms of the optical model and the extended (or coupled-channel) optical model, together with the relation of these models to microscopic calculations of the nucleon-nucleon interaction. Comparisons between neutron elastic data and calculations carried out with optical model potentials obtained from (p,p) and (p,n) data are presented for a large number of nuclei. The validity of the Lane model and the importance of coupled effects in the actinide region are shown in a detailed comparison of calculations for elastic and inelastic neutron differential cross sections and measurements for 232 Th and 238 U

Neutron radiography with the cyclotron

International Nuclear Information System (INIS)

Tazawa, Shuichi; Asada, Yorihisa; Yano, Munehiko; Nakanii, Takehiko.

1985-01-01

Neutron radiography is well recognized as a powerful tool in nondestructive testing, but not widely used yet owing to lack of high intense thermal neutron source convenient for practical use. This article presents a new neutron radiograph facility, utilizing a sub-compact cyclotron as neutron source and is equipped with vertical and horizontal irradiation ports. The article describes a series of experiments, we conducted using beams of a variable energy cyclotron at Tohoku University to investigate the characteristics of thermal neutron obtained from 9 Be(p, n) reaction and thermalized by elastic scattering process. The article also describes a computer simulation of neutron moderator to analyze conditions getting maximal thermal neutron flux. Further, some of practical neutron radiograph examinations of aero-space components and museum art objects of classic bronze mirror and an attempt realizing real time imaging technique, are introduced in the article. (author)

Neutron diffractometer for bio-crystallography (BIX) with an imaging plate neutron detector

Energy Technology Data Exchange (ETDEWEB)

Niimura, Nobuo [Japan Atomic Energy Research Inst., Ibaraki-ken (Japan)

1994-12-31

We have constructed a dedicated diffractometer for neutron crystallography in biology (BIX) on the JRR-3M reactor at JAERI (Japan Atomic Energy Research Institute). The diffraction intensity from a protein crystal is weaker than that from most inorganic materials. In order to overcome the intensity problem, an elastically bent silicon monochromator and a large area detector system were specially designed. A preliminary result of diffraction experiment using BIX has been reported. An imaging plate neutron detector has been developed and a feasibility experiment was carried out on BIX. Results are reported. An imaging plate neutron detector has been developed and a feasibility test was carried out using BIX.

Spin observables in proton-neutron scattering at intermediate energy

International Nuclear Information System (INIS)

Spinka, H.

1986-05-01

A summary of np elastic scattering spin measurements at intermediate energy is given. Preliminary results from a LAMPF experiment to measure free neutron-proton elastic scattering spin-spin correlation parameters are presented. A longitudinally polarized proton target was used. These measurements are part of a program to determine the neutron-proton amplitudes in a model independent fashion at 500, 650, and 800 MeV. Some new proton-proton total cross sections in pure helicity states (Δσ/sub L/(pp)) near 3 GeV/c are also given. 37 refs., 2 figs

A review of conventional explosives detection using active neutron interrogation

International Nuclear Information System (INIS)

Whetstone, Z.D.; Kearfott, K.J.

2014-01-01

Conventional explosives are relatively easy to obtain and may cause massive harm to people and property. There are several tools employed by law enforcement to detect explosives, but these can be subverted. Active neutron interrogation is a viable alternative to those techniques, and includes: fast neutron analysis, thermal neutron analysis, pulsed fast/thermal neutron analysis, neutron elastic scatter, and fast neutron radiography. These methods vary based on neutron energy and radiation detected. A thorough review of the principles behind, advantages, and disadvantages of the different types of active neutron interrogation is presented. (author)

Full counting statistics of multiple Andreev reflections in incoherent diffusive superconducting junctions

International Nuclear Information System (INIS)

Samuelsson, P.

2007-01-01

We present a theory for the full distribution of current fluctuations in incoherent diffusive superconducting junctions, subjected to a voltage bias. This theory of full counting statistics of incoherent multiple Andreev reflections is valid for an arbitrary applied voltage. We present a detailed discussion of the properties of the first four cumulants as well as the low and high voltage regimes of the full counting statistics. (orig.)

On the application of the theory of the translational Brownian movement to the calculation of the differential cross-sections for the incoherent scattering of slow neutrons

International Nuclear Information System (INIS)

Coffey, W.T.

1978-01-01

It is shown how three models (based on the theory of the Brownian movement) for the translational motion of an atom in a fluid may be used to calculate explicitly the intermediate scattering functions and differential cross-sections for the incoherent scattering of slow neutrons. In the first model the translational motion of the atom is represented by the motion of a particle in space subjected to no forces other than those arising from the thermal motion of its surroundings. The differential scattering cross-section for this model is then obtained as a continued fraction similar to that given by Sack (Proc. Phys. Soc.; B70:402 and 414 (1957)) for the electric polarisability in his investigation of the role of inertial effects in dielectric relaxation. The second model is a corrected version of the itinerant oscillator model of Sears (Proc. Phys. Soc.; 86:953 (1965)). Here the differential cross-section is obtained in the form of a series and a closed-form expression is found for the intermediate scattering function. The last model to be considered is the harmonically bound particle where again a closed form expression is obtained for the intermediate scattering function. In each case the intermediate scattering function has a mathematical form which is similar to the after-effect function describing the decay of electric polarisation for the rotational versions of the models. (author)

Some improved methods in neutron transport theory

Energy Technology Data Exchange (ETDEWEB)

Pop-Jordanov, J; Stefanovic, D; Kocic, A; Matausek, M; Bosevski, T [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

1973-07-01

The methods described in this paper are: analytical approach to neutron spectra in case of energy dependent anisotropy of elastic scattering; Monte Carlo estimations of neutron absorption reaction rate during slowing down process; spherical harmonics treatment of space-angle-lethargy dependent slowing down transport equation; integral transport theory based on point-wise representation of variables.

DEMONR, Monte-Carlo Shielding Calculation for Neutron Flux and Neutron Spectra, Teaching Program

International Nuclear Information System (INIS)

Courtney, J. C.

1987-01-01

1 - Description of problem or function: DEMONR treats the behavior of neutrons in a slab shield. It is frequently used as a teaching tool. 2 - Method of solution: An unbiased Monte Carlo code calculates the number, energy, and direction of neutrons that penetrate or are reflected from a shield. 3 - Restrictions on the complexity of the problem: Only one shield may be used in each problem. The shield material may be a single element or a homogeneous mixture of elements with a single effective atomic weight. Only elastic scattering and neutron capture processes are allowed. The source is a point located on one face of the slab. It provides a cosine distribution of current. Monoenergetic or fission spectrum neutrons may be selected

Scattering of 14.2 MeV polarized neutrons from 12C

International Nuclear Information System (INIS)

Casparis, R.; Leemann, B.Th.; Preiswerk, M.; Rudin, H.; Wagner, R.; Zupranski, P.

1976-01-01

Polarized 14.2 MeV neutrons with a polarization of approximately 50% were produced in the 3 H(d(pol),n(pol)) 4 He reaction using vector polarized deuterons from an 'atomic beam' source of polarized ions. The angular distributions of the analyzing power in the elastic and inelastic (Q = -4.43 MeV) scattering of neutrons from carbon have been measured at ten angles in the range from 22 0 to 152 0 c.m. A time-of-flight technique was used to separate elastically and inelastically scattered neutrons. The results have been compared with theoretical calculations obtained with the DWBA and the coupled channels method. (Auth.)

Elastic/Inelastic Measurement Project

International Nuclear Information System (INIS)

Yates, Steven; Hicks, Sally; Vanhoy, Jeffrey; McEllistrem, Marcus

2015-12-01

The work scope involves the measurement of neutron scattering from natural sodium ( 23 Na) and two isotopes of iron, 56 Fe and 54 Fe. Angular distributions, i.e., differential cross sections, of the scattered neutrons will be measured for 5 to 10 incident neutron energies per year. The work of the first year concentrates on 23 Na, while the enriched iron samples are procured. Differential neutron scattering cross sections provide information to guide nuclear reaction model calculations in the low-@@energy (few MeV) fast-@@neutron region. This region lies just above the isolated resonance region, which in general is well studied; however, model calculations are difficult in this region because overlapping resonance structure is evident and direct nuclear reactions are becoming important. The standard optical model treatment exhibits good predictive ability for the wide-@@region average cross sections but cannot treat the overlapping resonance features. In addition, models that do predict the direct reaction component must be guided by measurements to describe correctly the strength of the direct component, e.g., @@ 2 must be known to describe the direct component of the scattering to the first excited state. Measurements of the elastic scattering differential cross sections guide the optical model calculations, while inelastic differential cross sections provide the crucial information for correctly describing the direct component. Activities occurring during the performance period are described.

Resolution of coherent and incoherent imaging systems reconsidered : Classical criteria and a statistical alternative

NARCIS (Netherlands)

Van Aert, S.; Van Dyck, D.; Den Dekker, A.J.

2006-01-01

The resolution of coherent and incoherent imaging systems is usually evaluated in terms of classical resolution criteria, such as Rayleigh’s. Based on these criteria, incoherent imaging is generally concluded to be ‘better’ than coherent imaging. However, this paper reveals some misconceptions in

Electromagnetically induced two-dimensional grating assisted by incoherent pump

Energy Technology Data Exchange (ETDEWEB)

Chen, Yu-Yuan; Liu, Zhuan-Zhuan; Wan, Ren-Gang, E-mail: wrg@snnu.edu.cn

2017-04-25

We propose a scheme for realizing electromagnetically induced two-dimensional grating in a double-Λ system driven simultaneously by a coherent field and an incoherent pump field. In such an atomic configuration, the absorption is suppressed owing to the incoherent pumping process and the probe can be even amplified, while the refractivity is mainly attributed to the dynamically induced coherence. With the help of a standing-wave pattern coherent field, we obtain periodically modulated refractive index without or with gain, and therefore phase grating or gain-phase grating which diffracts a probe light into high-order direction efficiently can be formed in the medium via appropriate manipulation of the system parameters. The diffraction efficiency attainable by the present gratings can be controlled by tuning the coherent field intensity or the interaction length. Hence, the two-dimensional grating can be utilized as all-optical splitter or router in optical networking and communication. - Highlights: • Two-dimensional grating is coherently induced in four-level atoms. • Phase and gain-phase gratings are obtained assisted by incoherent pump. • The diffraction power is improved due to the enhanced refraction modulation. • The gratings can be utilized as multi-channel all-optical splitter and router.

Fast-neutron scattering from elemental cadmium

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.

1982-07-01

Neutron differential-elastic-scattering cross sections of elemental cadmium are measured from approx. = 1.5 to 4.0 MeV at incident-neutron energy intervals of 50 to 200 keV and at 10 to 20 scattering angles distributed between approx. = 20 and 160 degrees. Concurrently, lumped-level neutron inelastic-excitation cross sections are measured. The experimental results are used to deduce parameters of an optical-statistical model that is descriptive of the observables and are compared with corresponding quantities given in ENDF/B-V

Fast neutron analysis code SAD1

International Nuclear Information System (INIS)

Jung, M.; Ott, C.

1985-01-01

A listing and an example of outputs of the M.C. code SAD1 are given here. This code has been used many times to predict responses of fast neutrons in hydrogenic materials (in our case emulsions or plastics) towards the elastic n, p scattering. It can be easily extended to other kinds of such materials and to any kind of incident fast neutron spectrum

Studies of the dynamic properties of materials using neutron scattering

International Nuclear Information System (INIS)

Lovesey, S.W.; Windsor, C.G.

1985-09-01

The dynamic properties of materials using the neutron scattering technique is reviewed. The basic properties of both nuclear scattering and magnetic scattering are summarized. The experimental methods used in neutron scattering are described, along with access to neutron sources, and neutron inelastic instruments. Applied materials science using inelastic neutron scattering; rotational tunnelling of a methyl group; molecular diffusion from quasi-elastic scattering; and the diffusion of colloidal particles and poly-nuclear complexes; are also briefly discussed. (U.K.)

The Precautionary Principle Has Not Been Shown to Be Incoherent: A Reply to Peterson.

Science.gov (United States)

Boyer-Kassem, Thomas

2017-11-01

In this journal, I have objected to Peterson's 2006 claim that the precautionary principle is an incoherent decision rule. I defend my objections to Peterson's recent replies, and I still claim that the precautionary principle has not been shown to be incoherent. © 2017 Society for Risk Analysis.

Neutron scattering treatise on materials science and technology

CERN Document Server

Kostorz, G

1979-01-01

Treatise on Materials Science and Technology, Volume 15: Neutron Scattering shows how neutron scattering methods can be used to obtain important information on materials. The book discusses the general principles of neutron scattering; the techniques used in neutron crystallography; and the applications of nuclear and magnetic scattering. The text also describes the measurement of phonons, their role in phase transformations, and their behavior in the presence of crystal defects; and quasi-elastic scattering, with its special merits in the study of microscopic dynamical phenomena in solids and

The theory of neutron scattering from mixed harmonic solids

International Nuclear Information System (INIS)

Warner, M.; Lovesey, S.W.; Smith, J.

1982-12-01

The dynamic structure factor for incoherent neutron scattering from light mass particles substituted in a solid is calculated for two model systems. One model is appropriate for a dilute concentration of light particles in a matrix, and the second is a binary system with various masses and force constants. The exact calculations are used to assess the value of approximation schemes for the dynamic structure factor which exploit the separation of time scales in the motions of the light and the heavier lattice particles. (author)

Coherent and Incoherent Neutral Current Scattering for Supernova Detection

Directory of Open Access Journals (Sweden)

P. C. Divari

2012-01-01

Full Text Available The total cross sections as well as the neutrino event rates are calculated in the neutral current neutrino scattering off 40Ar and 132Xe isotopes at neutrino energies (Ev<100 MeV. The individual contribution coming from coherent and incoherent channels is taking into account. An enhancement of the neutral current component is achieved via the coherent (0gs+→0gs+ channel which is dominant with respect to incoherent (0gs+→Jf one. The response of the above isotopes as a supernova neutrino detection has been considered, assuming a two parameter Fermi-Dirac distribution for the supernova neutrino energy spectra. The calculated total cross sections are tested on a gaseous spherical TPC detector dedicated for supernova neutrino detection.

Neutron scattering studies of solid electrolytes

International Nuclear Information System (INIS)

Shapiro, S.M.

1976-01-01

The role which neutron scattering can play in determining the nature of the disorder and the conducting mechanism in the solid electrolytes is discussed. First, some of the general formalism for elastic and inelastic neutron scattering is reviewed, and the quantities which can be measured are pointed out. Then the application of neutron scattering to the studies of three different problems is examined; the anion disorder in the fluorite system, the dynamical behavior in beta-alumina, and the cation diffusion in αAgI are discussed. 8 figures

Some remarks on the neutron elastic- and enelastic-scattering cross sections of palladium

International Nuclear Information System (INIS)

Chiba, S.; Guenther, P.T.; Smith, A.B.

1989-05-01

The cross sections for the elastic-scattering of 5.9, 7.1 and 8.0 MeV neutrons from elemental palladium were measured at forty scattering angles distributed between ∼15/degree/ and 160/degree/. The inelastic-scattering cross sections for the excitation of palladium levels at energies of 260 keV to 560 keV were measured with high resolution at the same energies, and at a scattering angle of 80/degree/. The experimental results were combined with lower-energy values previously obtained by this group to provide a comprehensive data base extending from near the inelastic-scattering threshold to 8 MeV. That data base was interpreted in terms of a coupled-channel model, including the inelastic excitation of one- and two-phonon vibrational levels of the even isotopes of palladium. It was concluded that the palladium inelastic-scattering cross section, at the low energies of interest in assessment of fast-fission-reactor performance, are large (∼50% greater than given in widely used evaluated fission-product data files). They primarily involve compound-nucleus processes, with only a small direct-reaction component attributable to the excitation of the one-phonon, 2 + , vibrational levels of the even isotopes of palladium. 24 refs., 6 figs

Neutron radiography with the cyclotron, 3

International Nuclear Information System (INIS)

Hiraoka, Eiichi; Fujishiro, Masatoshi; Tsujii, Yukio

1985-01-01

Neutron radiography is well recognized as a powerful tool in nondestructive testing, but not widely used yet owing to lack of high intense thermal neutron source convenient for practical use. A new neutron radiograph facility, utilizing a sub-compact cyclotron as neutron source and equipped with vertical and horizontal irradiation ports, is presented in this article. A series of experiment, prior to its construction, was conducted using beams of a variable energy cyclotron at Tohoku University to investigate the characteristics of thermal neutron obtained, from 9 Be (p, n) reaction and thermalized by elastic scattering process. This article describes a computer simulation of neutron moderator to analyze conditions getting maximal thermal neutron flux. Some of practical neutron radiograph examination of aero-space components and museum art objects of classic bronze mirror are also presented together with an attempt realizing real time imaging technique. (author)

Magnetic anisotropy and neutron scattering studies of some rare earth metals

International Nuclear Information System (INIS)

Day, R.

1978-08-01

The thesis is concerned with magnetic anisotropy of dysprosium and alloys of gadolinium: yttrium, and also neutron scattering studies of dysprosium. The experiments are discussed under the topic headings: magnetic anisotropy, rare earths, torque measurements, elastic neutron scattering, inelastic neutron scattering, dysprosium measurements, and results for the gadolinium: yttrium alloys. (U.K.)

Neutrons moderation theory; Theorie du ralentissement des neutrons

Energy Technology Data Exchange (ETDEWEB)

Vigier, J P

1949-07-01

This report gives a summarized presentation of the theory of fast neutrons diffusion and moderation in a given environment as elaborated by M. Langevin, E. Fermi, R. Marshak and others. This statistical theory is based on three assumptions: there is no inelastic diffusion, the elastic diffusion has a spherical symmetry with respect to the center of gravity of the neutron-nucleus system (s-scattering), and the effects of chemical bonds and thermal agitation of nuclei are neglected. The first chapter analyzes the Boltzmann equation of moderation, its first approximate solution (age-velocity equation) and its domain of validity, the extension of the age-velocity theory (general solution) and the boundary conditions, the upper order approximation (spherical harmonics method and Laplace transformation), the asymptotic solutions, and the theory of spatial momenta. The second chapter analyzes the energy distribution of delayed neutrons (stationary and non-stationary cases). (J.S.)

Role of water on formation and structural features of Maya blue

International Nuclear Information System (INIS)

Mondelli, C; Río, M Sánchez del; González, M A; Magazzú, A; Cavallari, C; Suárez, M; García-Romero, E; Romano, P

2012-01-01

The Maya blue (MB) is an artificial pigment created between 500-800 A.D. and used in murals, pottery and sculptures by Mayas and other people in Mesoamerica. MB is resistant to age, acid, weathering, biodegradation and even modern chemical solvents, but the chemical reasons behind the resistance to chemical aggressions are still under debate. Water plays a fundamental role in the interactions between indigo and clay. The dynamics of the clay's zeolitic and structural water molecules during the formation of MB, usually stabilized by moderate heating, has been monitored by means of neutron inelastic scattering. Neutron incoherent scattering in these samples is only due to the hydrogen atoms, so the signal is very sensitive to the amount of released water, providing detailed information on the dehydration process. A simultaneous analysis of the coherent elastic scattering and the incoherent scattering allows observing and quantifying how the structure of the clay is affected by dehydration. Here we show that a quite resistant pigment can be obtained at room temperature simply by dehydrating a palygorskite-indigo mixture employing only vacuum, without any thermal treatment.

Role of water on formation and structural features of Maya blue

Science.gov (United States)

Mondelli, C.; Sánchez del Río, M.; González, M. A.; Magazzú, A.; Cavallari, C.; Suárez, M.; García-Romero, E.; Romano, P.

2012-02-01

The Maya blue (MB) is an artificial pigment created between 500-800 A.D. and used in murals, pottery and sculptures by Mayas and other people in Mesoamerica. MB is resistant to age, acid, weathering, biodegradation and even modern chemical solvents, but the chemical reasons behind the resistance to chemical aggressions are still under debate. Water plays a fundamental role in the interactions between indigo and clay. The dynamics of the clay's zeolitic and structural water molecules during the formation of MB, usually stabilized by moderate heating, has been monitored by means of neutron inelastic scattering. Neutron incoherent scattering in these samples is only due to the hydrogen atoms, so the signal is very sensitive to the amount of released water, providing detailed information on the dehydration process. A simultaneous analysis of the coherent elastic scattering and the incoherent scattering allows observing and quantifying how the structure of the clay is affected by dehydration. Here we show that a quite resistant pigment can be obtained at room temperature simply by dehydrating a palygorskite-indigo mixture employing only vacuum, without any thermal treatment.

Recent research on nuclear reaction using high-energy proton and neutron

Energy Technology Data Exchange (ETDEWEB)

Shibata, Tokushi [Tokyo Univ., Tanashi (Japan). Inst. for Nuclear Study

1997-11-01

The presently available high-energy neutron beam facilities are introduced. Then some interesting research on nuclear reaction using high-energy protons are reported such as the intermediate mass fragments emission and neutron spectrum measurements on various targets. As the important research using high-energy neutron, the (p,n) reactions on Mn, Fe, and Ni, the elastic scattering of neutrons, and the shielding experiments are discussed. (author)

Time-stretch microscopy based on time-wavelength sequence reconstruction from wideband incoherent source

International Nuclear Information System (INIS)

Zhang, Chi; Xu, Yiqing; Wei, Xiaoming; Tsia, Kevin K.; Wong, Kenneth K. Y.

2014-01-01

Time-stretch microscopy has emerged as an ultrafast optical imaging concept offering the unprecedented combination of the imaging speed and sensitivity. However, dedicated wideband and coherence optical pulse source with high shot-to-shot stability has been mandated for time-wavelength mapping—the enabling process for ultrahigh speed wavelength-encoded image retrieval. From the practical point of view, exploiting methods to relax the stringent requirements (e.g., temporal stability and coherence) for the source of time-stretch microscopy is thus of great value. In this paper, we demonstrated time-stretch microscopy by reconstructing the time-wavelength mapping sequence from a wideband incoherent source. Utilizing the time-lens focusing mechanism mediated by a narrow-band pulse source, this approach allows generation of a wideband incoherent source, with the spectral efficiency enhanced by a factor of 18. As a proof-of-principle demonstration, time-stretch imaging with the scan rate as high as MHz and diffraction-limited resolution is achieved based on the wideband incoherent source. We note that the concept of time-wavelength sequence reconstruction from wideband incoherent source can also be generalized to any high-speed optical real-time measurements, where wavelength is acted as the information carrier

The importance of anisotropic scattering in high energy neutron transport problems

International Nuclear Information System (INIS)

Prillinger, G.; Mattes, M.

1984-01-01

To describe the highly anisotropic scattering of very fast neutrons adequately the transport code ANISN has been improved. Fokker-Planck terms have been introduced into the transport equation which accurately describe the small changes in energy and angle. The new code has been tested for a d(50)-Be neutron source in a deep penetration iron problem. The influence of the forward peaked elastic scattering on the fast neutron spectrum is shown to be significant and can be handled efficiently in the new ANISN version. Since common cross-section libraries are limited by Legendre expansion, or by their upper energy boundary, or exclude elastic scattering above 20 MeV a special library has been created. (Auth.)

Incoherent control of locally controllable quantum systems

International Nuclear Information System (INIS)

Dong Daoyi; Zhang Chenbin; Rabitz, Herschel; Pechen, Alexander; Tarn, T.-J.

2008-01-01

An incoherent control scheme for state control of locally controllable quantum systems is proposed. This scheme includes three steps: (1) amplitude amplification of the initial state by a suitable unitary transformation, (2) projective measurement of the amplified state, and (3) final optimization by a unitary controlled transformation. The first step increases the amplitudes of some desired eigenstates and the corresponding probability of observing these eigenstates, the second step projects, with high probability, the amplified state into a desired eigenstate, and the last step steers this eigenstate into the target state. Within this scheme, two control algorithms are presented for two classes of quantum systems. As an example, the incoherent control scheme is applied to the control of a hydrogen atom by an external field. The results support the suggestion that projective measurements can serve as an effective control and local controllability information can be used to design control laws for quantum systems. Thus, this scheme establishes a subtle connection between control design and controllability analysis of quantum systems and provides an effective engineering approach in controlling quantum systems with partial controllability information.

Experimental photonic generation of chirped pulses using nonlinear dispersion-based incoherent processing.

Science.gov (United States)

Rius, Manuel; Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José

2015-05-18

We experimentally demonstrate, for the first time, a chirped microwave pulses generator based on the processing of an incoherent optical signal by means of a nonlinear dispersive element. Different capabilities have been demonstrated such as the control of the time-bandwidth product and the frequency tuning increasing the flexibility of the generated waveform compared to coherent techniques. Moreover, the use of differential detection improves considerably the limitation over the signal-to-noise ratio related to incoherent processing.

The Precautionary Principle Has Not Been Shown to Be Incoherent: A Reply to Peterson : Response

NARCIS (Netherlands)

Boyer-Kassem, Thomas

2017-01-01

In this journal, I have objected to Peterson's 2006 claim that the precautionary principle is an incoherent decision rule. I defend my objections to Peterson's recent replies, and I still claim that the precautionary principle has not been shown to be incoherent.

Accelerator driven reactors, - the significance of the energy distribution of spallation neutrons on the neutron statistics

Energy Technology Data Exchange (ETDEWEB)

Fhager, V

2000-01-01

In order to make correct predictions of the second moment of statistical nuclear variables, such as the number of fissions and the number of thermalized neutrons, the dependence of the energy distribution of the source particles on their number should be considered. It has been pointed out recently that neglecting this number dependence in accelerator driven systems might result in bad estimates of the second moment, and this paper contains qualitative and quantitative estimates of the size of these efforts. We walk towards the requested results in two steps. First, models of the number dependent energy distributions of the neutrons that are ejected in the spallation reactions are constructed, both by simple assumptions and by extracting energy distributions of spallation neutrons from a high-energy particle transport code. Then, the second moment of nuclear variables in a sub-critical reactor, into which spallation neutrons are injected, is calculated. The results from second moment calculations using number dependent energy distributions for the source neutrons are compared to those where only the average energy distribution is used. Two physical models are employed to simulate the neutron transport in the reactor. One is analytical, treating only slowing down of neutrons by elastic scattering in the core material. For this model, equations are written down and solved for the second moment of thermalized neutrons that include the distribution of energy of the spallation neutrons. The other model utilizes Monte Carlo methods for tracking the source neutrons as they travel inside the reactor material. Fast and thermal fission reactions are considered, as well as neutron capture and elastic scattering, and the second moment of the number of fissions, the number of neutrons that leaked out of the system, etc. are calculated. Both models use a cylindrical core with a homogenous mixture of core material. Our results indicate that the number dependence of the energy

Accelerator driven reactors, - the significance of the energy distribution of spallation neutrons on the neutron statistics

International Nuclear Information System (INIS)

Fhager, V.

2000-01-01

In order to make correct predictions of the second moment of statistical nuclear variables, such as the number of fissions and the number of thermalized neutrons, the dependence of the energy distribution of the source particles on their number should be considered. It has been pointed out recently that neglecting this number dependence in accelerator driven systems might result in bad estimates of the second moment, and this paper contains qualitative and quantitative estimates of the size of these efforts. We walk towards the requested results in two steps. First, models of the number dependent energy distributions of the neutrons that are ejected in the spallation reactions are constructed, both by simple assumptions and by extracting energy distributions of spallation neutrons from a high-energy particle transport code. Then, the second moment of nuclear variables in a sub-critical reactor, into which spallation neutrons are injected, is calculated. The results from second moment calculations using number dependent energy distributions for the source neutrons are compared to those where only the average energy distribution is used. Two physical models are employed to simulate the neutron transport in the reactor. One is analytical, treating only slowing down of neutrons by elastic scattering in the core material. For this model, equations are written down and solved for the second moment of thermalized neutrons that include the distribution of energy of the spallation neutrons. The other model utilizes Monte Carlo methods for tracking the source neutrons as they travel inside the reactor material. Fast and thermal fission reactions are considered, as well as neutron capture and elastic scattering, and the second moment of the number of fissions, the number of neutrons that leaked out of the system, etc. are calculated. Both models use a cylindrical core with a homogenous mixture of core material. Our results indicate that the number dependence of the energy

The analysis of the elastic scattering of {sup 11}Be and {sup 6}Li by adiabatic approximation

Energy Technology Data Exchange (ETDEWEB)

Takagi, S. [Osaka City Univ. (Japan). Dept. of Physics

2000-01-01

The unstable nuclei, particularly, the neutron halo nuclei which exist near by the neutron dripline, are recently one of the interesting topics in the nuclear physics. By the adiabatic approximation, R. C. Jhonson et al. have reproduced the experimental differential cross-section of the elastic scattering of the neutron halo nucleus {sup 11}Be (+{sup l2}C) [1]. We have applied their method to the elastic scattering of another nucleus {sup 6}Li which is not a halo nucleus but has the cluster structure as {sup 11}Be. But it couldn't reproduce the experimental data, so that the method of Johnson et al. is poor in the case of {sup 6}Li. (author)

Elastic/Inelastic Measurement Project

Energy Technology Data Exchange (ETDEWEB)

Yates, Steven [Univ. of Kentucky, Lexington, KY (United States); Hicks, Sally [Univ. of Dallas, TX (United States); Vanhoy, Jeffrey [U.S. Naval Academy, Annapolis, MD (United States); McEllistrem, Marcus [Univ. of Kentucky, Lexington, KY (United States)

2016-03-01

The work scope involves the measurement of neutron scattering from natural sodium (²³Na) and two isotopes of iron, ⁵⁶Fe and ⁵⁴Fe. Angular distributions, i.e., differential cross sections, of the scattered neutrons will be measured for 5 to 10 incident neutron energies per year. The work of the first year concentrates on ²³Na, while the enriched iron samples are procured. Differential neutron scattering cross sections provide information to guide nuclear reaction model calculations in the low-­energy (few MeV) fast-­neutron region. This region lies just above the isolated resonance region, which in general is well studied; however, model calculations are difficult in this region because overlapping resonance structure is evident and direct nuclear reactions are becoming important. The standard optical model treatment exhibits good predictive ability for the wide-­region average cross sections but cannot treat the overlapping resonance features. In addition, models that do predict the direct reaction component must be guided by measurements to describe correctly the strength of the direct component, e.g., β₂ must be known to describe the direct component of the scattering to the first excited state. Measurements of the elastic scattering differential cross sections guide the optical model calculations, while inelastic differential cross sections provide the crucial information for correctly describing the direct component. Activities occurring during the performance period are described.

Neutron shielding performance of water-extended polyester

International Nuclear Information System (INIS)

Vega Carrillo, H.R.; Manzanares-Acuna, E.; Hernandez-Davila, V.M.; Vega Carrillo, H.R.; Hernandez-Davila, V.M.; Gallego, E.; Lorente, A.

2006-01-01

A Monte Carlo study to determine the shielding features to neutrons of water-extended polyester (WEP) was carried out. Materials with low atomic number are predominantly used for neutron shielding because these materials effectively attenuate neutrons, mainly through elastic and inelastic collisions. In addition to neutron attenuation properties, other desirable properties for neutron shielding materials include mechanical strength, stability, low cost, and ease of handling. During the selection of materials to design a neutron shield, prompt gamma production as well as radionuclide induced by neutron activation must be considered. In this investigation the Monte Carlo method (MCNP code) was used to evaluate the performance of a water-extended polyester shield designed for the transportation, storage, and use of a 252 Cf isotopic neutron source, for comparison the calculations were extended to water shielding, the bare source in vacuum and in air. (authors)

Neutron shielding performance of water-extended polyester

Energy Technology Data Exchange (ETDEWEB)

Vega Carrillo, H.R.; Manzanares-Acuna, E.; Hernandez-Davila, V.M. [Zacatecas Univ. Autonoma, Nuclear Studies (Mexico); Vega Carrillo, H.R.; Hernandez-Davila, V.M. [Zacatecas Univ. Autonoma, Electric Engineering Academic Units (Mexico); Gallego, E.; Lorente, A. [Madrid Univ. Politecnica, cNuclear Engineering Department (Mexico)

2006-07-01

A Monte Carlo study to determine the shielding features to neutrons of water-extended polyester (WEP) was carried out. Materials with low atomic number are predominantly used for neutron shielding because these materials effectively attenuate neutrons, mainly through elastic and inelastic collisions. In addition to neutron attenuation properties, other desirable properties for neutron shielding materials include mechanical strength, stability, low cost, and ease of handling. During the selection of materials to design a neutron shield, prompt gamma production as well as radionuclide induced by neutron activation must be considered. In this investigation the Monte Carlo method (MCNP code) was used to evaluate the performance of a water-extended polyester shield designed for the transportation, storage, and use of a {sup 252}Cf isotopic neutron source, for comparison the calculations were extended to water shielding, the bare source in vacuum and in air. (authors)

Characteristics of Fabricated SiC Neutron Detectors for Neutron Flux Monitoring

Energy Technology Data Exchange (ETDEWEB)

Kim, Han Soo; Ha, Jang Ho; Park, Se Hwan; Lee, Kyu Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Cheol Ho [Hanyang University, Seoul (Korea, Republic of)

2011-05-15

An SPND (Self-powered Neutron Detector) is commonly used for neutron detection in NPP (Nuclear Power Plant) by virtue of un-reactivity for gamma-rays. But it has a drawback, which is that it cannot detect neutrons in real time due to beta emissions (about > 48 s) after reactions between neutrons and {sup 103}Rh in an SPND. And Generation IV reactors such as MSR (Molten-salt reactor), SFR (Sodium-cooled fast reactor), and GFR (Gas-cooled fast reactor) are designed to compact size and integration type. For GEN IV reactor, neutron monitor also must be compact-sized to apply such reactor easily and much more reliable. The wide band-gap semiconductors such as SiC, AlN, and diamond make them an attractive alternative in applications in harsh environments by virtue of the lower operating voltage, faster charge-collection times compared with gas-filled detectors, and compact size.1) In this study, two PIN-type SiC semiconductor neutron detectors, which are for fast neutron detection by elastic and inelastic scattering SiC atoms and for thermal neutron detection by charged particle emissions of 6LiF reaction, were designed and fabricated for NPP-related applications. Preliminary tests such as I-V and alpha response were performed and neutron responses at ENF in HANARO research reactor were also addressed. The application feasibility of the fabricated SiC neutron detector as an in-core neutron monitor was discussed

Ammonium dynamics in the disordered α-phase of K1-x(NH4)xY (Y = Cl, Br, I). A neutron scattering study

International Nuclear Information System (INIS)

Natkaniec, I.; Smirnov, L.S.; Shuvalov, L.A.

2002-01-01

The effect of temperature and concentration on the lattice parameters and amplitude-weighted phonon density of states in mixed salts of ammonium-potassium halides is investigated by neutron powder diffraction and incoherent inelastic neutron scattering. In the disordered α-phase (NaCl type) ammonium ions exhibit a fast stochastic reorientation at phonon frequency rates down to ca. 80 K. At 10 K, the incoherent inelastic neutron scattering spectra display four distinct ammonium excitations: two (resonant) modes below and two (localized) above the Debye cut-off energy of potassium halides. High-frequency localized modes correspond to translational and librational vibrations of NH 4 ions. These modes are typical for the ordered phases of ammonium halides. The effect of ammonium concentration on localized and resonant modes is studied for the K 1-x (NH 4 ) x I mixed salts. The harmonic excitations of ammonium in a hypothetical low-temperature α-phase of NH 4 I are approximated to ca. 30, 95, 155 and 250 cm -1 . In a real low-temperature ordered γ-phase of NH 4 I, translational ammonium vibrations are observed at ca. 140-160 cm -1 and librational vibrations at ca.300 cm -1

Neutron scattering studies in the actinide region. Progress report, August 1, 1991--July 31, 1994

International Nuclear Information System (INIS)

Kegel, G.H.R.; Egan, J.J.

1994-09-01

During the period August 1, 1991 to July 31, 1994 the authors report progress on the following: (a) prompt fission neutron energy spectra for 235 U and 239 Pu; (b) two-parameter measurement of nuclear lifetimes; (c) 'black' neutron detector; (d) data reduction techniques for neutron scattering experiments; (e) elastic and inelastic neutron scattering studies in 197 Au; (f) elastic and inelastic neutron scattering studies in 239 Pu; (g) neutron induced defects in silicon dioxide MOS structures; (h) response of a 235 U fission chamber near reaction thresholds; (i) efficiency calibration of a liquid scintillation detector using the WNR facility at LAMPF; (j) prompt fission neutron energy spectrum measurements below the incident neutron energy; (k) multi-parameter data acquisition system; (l) accelerator improvements; (m) non-DOE supported research. Eight Ph.D. dissertations and two M.S. theses were completed during the report period. Publications consisted of 6 journal articles, 10 conference proceedings, and 19 abstracts of presentations at scientific meetings. One invited talk was given

A system for fast neutron radiography

International Nuclear Information System (INIS)

Klann, R.T.

1996-01-01

A system has been designed and a neutron generator installed to perform fast neutron radiography. With this sytem, objects as small as a coin or as large as a waste drum can be radiographed. The neutron source is an MF Physics A-711 neutron generator which produces 3x10 10 neutrons/second with an average energy of 14.5 MeV. The radiography system uses x-ray scintillation screens and film in commercially available cassettes. The cassettes have been modified to include a thin sheet of plastic to convert neutrons to protons through elastic scattering from hydrogen and other low Z materials in the plastic. For film densities from 1.8 to 3.0, exposures range from 1.9x10 7 to 3.8x10 8 n/cm 2 depending on the type of screen and film

Measurement and theoretical analysis of neutron-induced neutron-emission reactions of 6Li at 10 to 20 MeV region

International Nuclear Information System (INIS)

Ibaraki, Masanobu; Baba, Mamoru; Matsuyama, Shigeo

1998-06-01

We have measured the neutron elastic and inelastic scattering double-differential cross sections of 6 Li at incident neutron energies of 11.5, 14.1 and 18.0 MeV. Based on this data, together with information from other works, a phenomenological neutron optical model potential (OMP) of 6 Li was constructed to describe the total and elastic scattering cross sections from 5 MeV to several tens MeV. This potential also describes well the inelastic scattering to the 1st excited state (E x = 2.186 MeV) via the DWBA calculation with the macroscopic vibrational model. The continuum neutron energy spectra and angular distributions were then analyzed by the theory of final-state interaction extended to the DWBA form, with the assumption that the d-α interaction is dominant in the 3-body final state consisting of n, d and α particles. Such a calculation was found to be successful in explaining the major part of the low-excitation neutron spectra and angular distribution down to the Q-value region of -9 MeV, except for the Q-value range where the n-α quasi-free scattering will give a non-negligible contribution at forward angles. (author). 60 refs

Atomic motions in solid and liquid methanol by neutron inelastic scattering

International Nuclear Information System (INIS)

Figueiredo Neto, A.M.; Vinhas, L.A.

1979-01-01

The frequency spectra of methanol in three phases liquid, crystal I and crystal II were determined by incoherent inelastic neutron scattering. The measurements were performed using a Beryllium Filter Time-of-Flight Spectrometer. Neutron inelastic scattering spectra and frequency spectra allowed assignments of five peaks, corresponding to frequencies: 420 cm -1 attributed to vibrational modes of crystalline lattice, 240 and 160 cm -1 associated to stretching of hydrogen bonds, 82 and 50 cm -1 interpreted as vibrational and torsional modes of CH 3 OH units in dimers, trimers, tetramers and pentames. The results suggest crystal I phase as an intermediate phase between liquid and crystal II, concerning the structural and dynamical properties of molecules and their correlation. The plastic character of crystal I is discussed. (Author) [pt

Nonlinear dispersion-based incoherent photonic processing for microwave pulse generation with full reconfigurability.

Science.gov (United States)

Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José

2012-03-12

A novel all-optical technique based on the incoherent processing of optical signals using high-order dispersive elements is analyzed for microwave arbitrary pulse generation. We show an approach which allows a full reconfigurability of a pulse in terms of chirp, envelope and central frequency by the proper control of the second-order dispersion and the incoherent optical source power distribution, achieving large values of time-bandwidth product.

Electrostatic levitation facility optimized for neutron diffraction studies of high temperature liquids at a spallation neutron source

Energy Technology Data Exchange (ETDEWEB)

Mauro, N. A., E-mail: namauro@noctrl.edu [Department of Physics, North Central College, Naperville, Illinois 60540 (United States); Vogt, A. J. [Instrument and Source Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Derendorf, K. S. [Mechanical Engineering and Materials Science, Washington University, St. Louis, Missouri 63130 (United States); Johnson, M. L.; Kelton, K. F. [Department of Physics and Institute of Materials Science and Engineering, Washington University, 1 Brookings Drive, St. Louis, Missouri 63130 (United States); Rustan, G. E.; Quirinale, D. G.; Goldman, A. I. [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Kreyssig, A. [Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States); Division of Materials Sciences and Engineering, Ames Laboratory, Ames, Iowa 50011 (United States); Lokshin, K. A. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Neuefeind, J. C.; An, Ke [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Wang, Xun-Li [Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Ave., Kowloon (Hong Kong); Egami, T. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Department of Physics and Astronomy, Joint Institute for Neutron Sciences, University of Tennessee, Knoxville, Tennessee 37996 (United States)

2016-01-15

Neutron diffraction studies of metallic liquids provide valuable information about inherent topological and chemical ordering on multiple length scales as well as insight into dynamical processes at the level of a few atoms. However, there exist very few facilities in the world that allow such studies to be made of reactive metallic liquids in a containerless environment, and these are designed for use at reactor-based neutron sources. We present an electrostatic levitation facility, NESL (for Neutron ElectroStatic Levitator), which takes advantage of the enhanced capabilities and increased neutron flux available at spallation neutron sources (SNSs). NESL enables high quality elastic and inelastic neutron scattering experiments to be made of reactive metallic and other liquids in the equilibrium and supercooled temperature regime. The apparatus is comprised of a high vacuum chamber, external and internal neutron collimation optics, and a sample exchange mechanism that allows up to 30 samples to be processed between chamber openings. Two heating lasers allow excellent sample temperature homogeneity, even for samples approaching 500 mg, and an automated temperature control system allows isothermal measurements to be conducted for times approaching 2 h in the liquid state, with variations in the average sample temperature of less than 0.5%. To demonstrate the capabilities of the facility for elastic scattering studies of liquids, a high quality total structure factor for Zr{sub 64}Ni{sub 36} measured slightly above the liquidus temperature is presented from experiments conducted on the nanoscale-ordered materials diffractometer (NOMAD) beam line at the SNS after only 30 min of acquisition time for a small sample (∼100 mg)

Vibronic dephasing model for coherent-to-incoherent crossover in DNA

Science.gov (United States)

Karasch, Patrick; Ryndyk, Dmitry A.; Frauenheim, Thomas

2018-05-01

In this paper, we investigate the interplay between coherent and incoherent charge transport in cytosine-guanine (GC-) rich DNA molecules. Our objective is to introduce a physically grounded approach to dephasing in large molecules and to understand the length-dependent charge transport characteristics, and especially the crossover from the coherent tunneling to incoherent hopping regime at different temperatures. Therefore, we apply the vibronic dephasing model and compare the results to the Büttiker probe model which is commonly used to describe decoherence effects in charge transport. Using the full ladder model and simplified one-dimensional model of DNA, we consider molecular junctions with alternating and stacked GC sequences and compare our results to recent experimental measurements.

ATLAS MDT neutron sensitivity measurement and modeling

International Nuclear Information System (INIS)

Ahlen, S.; Hu, G.; Osborne, D.; Schulz, A.; Shank, J.; Xu, Q.; Zhou, B.

2003-01-01

The sensitivity of the ATLAS precision muon detector element, the Monitored Drift Tube (MDT), to fast neutrons has been measured using a 5.5 MeV Van de Graaff accelerator. The major mechanism of neutron-induced signals in the drift tubes is the elastic collisions between the neutrons and the gas nuclei. The recoil nuclei lose kinetic energy in the gas and produce the signals. By measuring the ATLAS drift tube neutron-induced signal rate and the total neutron flux, the MDT neutron signal sensitivities were determined for different drift gas mixtures and for different neutron beam energies. We also developed a sophisticated simulation model to calculate the neutron-induced signal rate and signal spectrum for ATLAS MDT operation configurations. The calculations agree with the measurements very well. This model can be used to calculate the neutron sensitivities for different gaseous detectors and for neutron energies above those available to this experiment

Experimental evaluation of a polycrystal deformation modeling scheme using neutron diffraction measurements

DEFF Research Database (Denmark)

Clausen, Bjørn; Lorentzen, Torben

1997-01-01

The uniaxial behavior of aluminum polycrystals is simulated using a rate-independent incremental self-consistent elastic-plastic polycrystal deformation model, and the results are evaluated by neutron diffraction measurements. The elastic strains deduced from the model show good agreement...

Use of the associated particle technique in the fast neutron spectroscopy

International Nuclear Information System (INIS)

Aquirre O, G.A.

1978-01-01

Selecting a neutrons monoenergetic source it was found that the nuclear reaction D(d,n) 3 He can be used to measure nuclear sections and differentials in elastic nuclear reactions through the associated particle technique; the neutron beam energy is directly determined in time of flight spectrum of the neutron. The flux is determined by the number of 3 He ions observed in the charged particle spectrum. The neutron flux can be increased increasing the solid angle of the neutrons beam in two magnitude orders according to the results of neutrons beam profile measures. (author)

Coherence Inherent in an Incoherent Synchrotron Radio Source ...

Indian Academy of Sciences (India)

It is well known that synchrotron radiation mechanism does not allow MASER type coherent emission (Pacholczyk 1970). Here we show that coherence can naturally occur in a synchrotron ... cally thick region (Fig. 1), then divides the synchrotron spectrum into an incoherent. 1A thin flat circular unleavened Indian bread.

Incoherent-scatter computed tomography with monochromatic synchrotron x ray: feasibility of multi-CT imaging system for simultaneous measurement-of fluorescent and incoherent scatter x rays

Science.gov (United States)

Yuasa, T.; Akiba, M.; Takeda, T.; Kazama, M.; Hoshino, A.; Watanabe, Y.; Hyodo, K.; Dilmanian, F. A.; Akatsuka, T.; Itai, Y.

1997-10-01

We describe a new system of incoherent scatter computed tomography (ISCT) using monochromatic synchrotron X rays, and we discuss its potential to be used in in vivo imaging for medical use. The system operates on the basis of computed tomography (CT) of the first generation. The reconstruction method for ISCT uses the least squares method with singular value decomposition. The research was carried out at the BLNE-5A bending magnet beam line of the Tristan Accumulation Ring in KEK, Japan. An acrylic cylindrical phantom of 20-mm diameter containing a cross-shaped channel was imaged. The channel was filled with a diluted iodine solution with a concentration of 200 /spl mu/gI/ml. Spectra obtained with the system's high purity germanium (HPGe) detector separated the incoherent X-ray line from the other notable peaks, i.e., the iK/sub /spl alpha// and K/sub /spl beta/1/ X-ray fluorescent lines and the coherent scattering peak. CT images were reconstructed from projections generated by integrating the counts In the energy window centering around the incoherent scattering peak and whose width was approximately 2 keV. The reconstruction routine employed an X-ray attenuation correction algorithm. The resulting image showed more homogeneity than one without the attenuation correction.

Neutron shielding performance of water-extended polyester

International Nuclear Information System (INIS)

Vega Carrillo, H.R.; Manzanares-Acuna, E.; Hernandez-Davila, V.M.; Vega Carrillo, H.R.; Gallegoc, E.; Lorentec, A.; Hernandez-Davila, V.M.

2006-01-01

A Monte Carlo study to determine the shielding features to neutrons of water-extended polyester was carried out. Materials with low atomic number are predominantly used for neutron shielding because these materials effectively attenuate neutrons, mainly through elastic and inelastic collisions. In addition to neutron attenuation properties, other desirable properties for neutron shielding materials include mechanical strength, stability, low cost, and ease of handling. During the selection of materials to design a neutron shield, prompt gamma production as well as radionuclide induced by neutron activation must be considered. In this investigation the Monte Carlo method (M.C.N.P. code) was used to evaluate the performance of a water-extended polyester shield designed for the transportation, storage, and use of a 252 Cf isotopic neutron source, for comparison the calculations were extended to water shielding, the bare source in vacuum and in air. (authors)

Improvements in fast-neutron spectroscopy methods (1961); Amelioration des methodes de spectrometrie des neutrons rapides (1961)

Energy Technology Data Exchange (ETDEWEB)

Cambou, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-02-15

This research aimed at improving fast-neutron electronic detectors based on n-p elastic scattering. The first part concerns proportional counters; careful constructional methods have made it possible to plot mono-energetic neutron spectra in the range 700 keV - 3 MeV with a resolution of 7 per cent. The second part concerns scintillation counters: an organic scintillator and an inorganic scintillator covered with a thin layer of a scattering agent. An exact study of the types of scintillation has made it possible to develop efficient discriminator circuits. Different neutron spectra plotted in the presence of a strong gamma background are presented. The last part deals with the development of form discrimination methods for the study, in the actual beam, of the elastic scattering of 14.58 MeV electrons. With hydrogen, the distribution f ({phi}) of the recoil protons is f({phi}) = 1 + 0.034 cos {phi} + 0.042 cos{sup 2} {phi}. With tritium the scattering is strongly anisotropic; the curve representing the variation of the differential cross-section for the elastic scattering in the centre of mass system is obtained with a target containing 1 cm{sup 3} of tritium. (author) [French] Le travail a porte sur l'amelioration des detecteurs electroniques de neutrons rapides bases sur la diffusion elastique n-p. La premiere partie est relative aux compteurs proportionnels; des methodes soignees de fabrication ont permis des traces de spectres de neutrons monoenergetiques dans le domaine 700 keV - 3 MeV avec une resolution de 7 pour cent. La deuxieme partie est relative au compteur a scintillations; scintillateur organique et scintillateur mineral recouvert d'un diffuseur mince. Une etude precise des formes de scintillations a permis la mise au point de circuits discriminateurs efficaces. Differents spectres de neutrons traces en presence d'un fond gamma intense sont presentes. La derniere partie est relative a la mise en oeuvre des methodes de discrimination de forme pour l

Neutron-/sup 90/Zr mean field from a dispersive optical model analysis

International Nuclear Information System (INIS)

Delaroche, J.P.; Wang, Y.; Rapaport, J.

1989-01-01

Elastic scattering cross sections have been measured for 8, 10, and 24 MeV neutrons incident on /sup 90/Zr. These measurements, together with other neutron elastic scattering and total cross section data available up to 29 MeV, are used in grid searches to obtain an optical model potential which contains a dispersion relation term. This potential is then extrapolated toward negative energies to predict bound single-particle state properties. An overall good description of the data at positive and negative energies is achieved

Neutrons scattering studies in the actinide region

International Nuclear Information System (INIS)

Kegel, G.H.R.; Egan, J.J.

1992-09-01

During the report period were investigated the following areas: prompt fission neutron energy spectra measurements; neutron elastic and inelastic scattering from 239 Pu; neutron scattering in 181 Ta and 197 Au; response of a 235 U fission chamber near reaction thresholds; two-parameter data acquisition system; ''black'' neutron detector; investigation of neutron-induced defects in silicon dioxide; and multiple scattering corrections. Four Ph.D. dissertations and one M.S. thesis were completed during the report period. Publications consisted of three journal articles, four conference papers in proceedings, and eleven abstracts of presentations at scientific meetings. There are currently four Ph.D. and one M.S. candidates working on dissertations directly associated with the project. In addition, three other Ph.D. candidates are working on dissertations involving other aspects of neutron physics in this laboratory

Holographic fluorescence microscopy with incoherent digital holographic adaptive optics.

Science.gov (United States)

Jang, Changwon; Kim, Jonghyun; Clark, David C; Lee, Seungjae; Lee, Byoungho; Kim, Myung K

2015-01-01

Introduction of adaptive optics technology into astronomy and ophthalmology has made great contributions in these fields, allowing one to recover images blurred by atmospheric turbulence or aberrations of the eye. Similar adaptive optics improvement in microscopic imaging is also of interest to researchers using various techniques. Current technology of adaptive optics typically contains three key elements: a wavefront sensor, wavefront corrector, and controller. These hardware elements tend to be bulky, expensive, and limited in resolution, involving, for example, lenslet arrays for sensing or multiactuator deformable mirrors for correcting. We have previously introduced an alternate approach based on unique capabilities of digital holography, namely direct access to the phase profile of an optical field and the ability to numerically manipulate the phase profile. We have also demonstrated that direct access and compensation of the phase profile are possible not only with conventional coherent digital holography, but also with a new type of digital holography using incoherent light: selfinterference incoherent digital holography (SIDH). The SIDH generates a complex—i.e., amplitude plus phase—hologram from one or several interferograms acquired with incoherent light, such as LEDs, lamps, sunlight, or fluorescence. The complex point spread function can be measured using guide star illumination and it allows deterministic deconvolution of the full-field image. We present experimental demonstration of aberration compensation in holographic fluorescence microscopy using SIDH. Adaptive optics by SIDH provides new tools for improved cellular fluorescence microscopy through intact tissue layers or other types of aberrant media.

Coherent imaging with incoherent light in digital holographic microscopy

Science.gov (United States)

Chmelik, Radim

2012-01-01

Digital holographic microscope (DHM) allows for imaging with a quantitative phase contrast. In this way it becomes an important instrument, a completely non-invasive tool for a contrast intravital observation of living cells and a cell drymass density distribution measurement. A serious drawback of current DHMs is highly coherent illumination which makes the lateral resolution worse and impairs the image quality by a coherence noise and a parasitic interference. An uncompromising solution to this problem can be found in the Leith concept of incoherent holography. An off-axis hologram can be formed with arbitrary degree of light coherence in systems equipped with an achromatic interferometer and thus the resolution and the image quality typical for an incoherent-light wide-field microscopy can be achieved. In addition, advanced imaging modes based on limited coherence can be utilized. The typical example is a coherence-gating effect which provides a finite axial resolution and makes DHM image similar to that of a confocal microscope. These possibilities were described theoretically using the formalism of three-dimensional coherent transfer functions and proved experimentally by the coherence-controlled holographic microscope which is DHM based on the Leith achromatic interferometer. Quantitative-phase-contrast imaging is demonstrated with incoherent light by the living cancer cells observation and their motility evaluation. The coherence-gating effect was proved by imaging of model samples through a scattering layer and living cells inside an opalescent medium.

Program POD; A computer code to calculate nuclear elastic scattering cross sections with the optical model and neutron inelastic scattering cross sections by the distorted-wave born approximation

International Nuclear Information System (INIS)

Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Iwamoto, Osamu; Shibata, Keiichi; Nakagawa, Tsuneo; Fukahori, Tokio; Katakura, Jun-ichi

2005-07-01

The computer code, POD, was developed to calculate angle-differential cross sections and analyzing powers for shape-elastic scattering for collisions of neutron or light ions with target nucleus. The cross sections are computed with the optical model. Angle-differential cross sections for neutron inelastic scattering can also be calculated with the distorted-wave Born approximation. The optical model potential parameters are the most essential inputs for those model computations. In this program, the cross sections and analyzing powers are obtained by using the existing local or global parameters. The parameters can also be inputted by users. In this report, the theoretical formulas, the computational methods, and the input parameters are explained. The sample inputs and outputs are also presented. (author)

Phonons in Solid Hydrogen and Deuterium Studied by Inelastic Coherent Neutron Scattering

DEFF Research Database (Denmark)

Nielsen, Mourits

1973-01-01

Phonon dispersion relations have been measured by coherent neutron scattering in solid para-hydrogen and ortho-deuterium. The phonon energies are found to be nearly equal in the two solids, the highest energy in each case lying close to 10 meV. The pressure and temperature dependence of the phonon...... energies have been measured in ortho-deuterium and the lattice change determined by neutron diffraction. When a pressure of 275 bar is applied, the phonon energies are increased by about 10%, and heating the crystal to near the melting point decreases them by about 7%. The densities of states, the specific...... heats, and the Debye temperatures have been deduced and found to be in agreement with the published experimental results. The Debye temperatures are 118 K for hydrogen and 114 K for deuterium. For hydrogen the Debye-Waller factor has been measured by incoherent neutron scattering and it corresponds...

Measurement and theoretical analysis of neutron-induced neutron-emission reactions of {sup 6}Li at 10 to 20 MeV region

Energy Technology Data Exchange (ETDEWEB)

Ibaraki, Masanobu; Baba, Mamoru; Matsuyama, Shigeo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

1998-06-01

We have measured the neutron elastic and inelastic scattering double-differential cross sections of {sup 6}Li at incident neutron energies of 11.5, 14.1 and 18.0 MeV. Based on this data, together with information from other works, a phenomenological neutron optical model potential (OMP) of {sup 6}Li was constructed to describe the total and elastic scattering cross sections from 5 MeV to several tens MeV. This potential also describes well the inelastic scattering to the 1st excited state (E{sub x} = 2.186 MeV) via the DWBA calculation with the macroscopic vibrational model. The continuum neutron energy spectra and angular distributions were then analyzed by the theory of final-state interaction extended to the DWBA form, with the assumption that the d-{alpha} interaction is dominant in the 3-body final state consisting of n, d and {alpha} particles. Such a calculation was found to be successful in explaining the major part of the low-excitation neutron spectra and angular distribution down to the Q-value region of -9 MeV, except for the Q-value range where the n-{alpha} quasi-free scattering will give a non-negligible contribution at forward angles. (author). 60 refs.

Water dynamics as affected by interaction with biomolecules and change of thermodynamic state: a neutron scattering study

International Nuclear Information System (INIS)

Orecchini, A; Paciaroni, A; Petrillo, C; Sebastiani, F; Sacchetti, F; De Francesco, A

2012-01-01

The dynamics of water as subtly perturbed by both the interaction with biomolecules and the variation of temperature and pressure has been investigated via neutron scattering spectroscopy. A measurement of inelastic neutron scattering devoted to the study of the coherent THz dynamics of water in a water-rich mixture with DNA (hydration level of 1 g DNA/15 g D 2 O) at room temperature is reported. The DNA hydration water coherent dynamics is characterised by the presence of collective modes, whose dispersion relations are similar to those observed in bulk water. These dispersion relations are well described by the interaction model developed in the case of bulk water, and the existence of a fast sound is experimentally demonstrated. The behaviour of the collective water dynamics was complemented by studying the single-particle dynamics of bulk water along the isotherm T = 298 K in the pressure range 0.1-350 MPa by means of incoherent scattering. This experiment is an attempt to simulate the change of the water molecular arrangement due to the interaction with DNA, by increasing the pressure as the presence of the biomolecule produces an increase in the density. An anomaly is found in the behaviour of the relaxation time derived from the quasi-elastic scattering signal, which can be related to the hypothetical second critical point in water. This anomaly and the transition from slow to fast sound take place in the same Q range, thus suggesting that the two phenomena could be related at some microscopic level.

Polycrystalline deformation in engineering materials: Insights from neutron diffraction during loading

International Nuclear Information System (INIS)

Bourke, M.; Brown, D.

1999-01-01

In-situ measurements using the non-destructive penetration of neutrons are commonplace at neutron sources and permit investigations within environmental chambers at stress, pressure, or temperature. Many of these studies explore the microstructural performance of engineering materials under service conditions. For example, by measuring phase strains during the application of static loads, neutron diffraction provides insight into failure, relaxation and load transfer mechanisms. Mechanical loading of a sample on a neutron spectrometer is usually performed with a customized load frame (small enough to fit into the typically limited available space) with the load axis horizontal. Diffraction data are recorded using detectors that surround the sample and strains are determined from changes in the measured interplanar lattice spacings in directions determined by the scattering geometry. These elastic strains indicate how the applied stress is shared throughout the microstructure. During a test, conventional strain gauges also record the macroscopic strain; that is the sum of the plastic and elastic contributions. Beyond yield the plastic contribution usually dominates the total strain but the elastic phase strains respond to the applied stress at any given load and provide clues about which phase (in a multiphase system) or which crystal orientation (in a single phase polycrystal) dictates failure

Fast Neutron Detection Using Pixelated CdZnTe Spectrometers

Science.gov (United States)

Streicher, Michael; Goodman, David; Zhu, Yuefeng; Brown, Steven; Kiff, Scott; He, Zhong

2017-07-01

Fast neutrons are an important signature of special nuclear materials (SNMs). They have a low natural background rate and readily penetrate high atomic number materials that easily shield gamma-ray signatures. Therefore, they provide a complementary signal to gamma rays for detecting shielded SNM. Scattering kinematics dictate that a large nucleus (such as Cd or Te) will recoil with small kinetic energy after an elastic collision with a fast neutron. Charge carrier recombination and quenching further reduce the recorded energy deposited. Thus, the energy threshold of CdZnTe detectors must be very low in order to sense the small signals from these recoils. In this paper, the threshold was reduced to less than 5 keVee to demonstrate that the 5.9-keV X-ray line from 55Fe could be separated from electronic noise. Elastic scattering neutron interactions were observed as small energy depositions (less than 20 keVee) using digitally sampled pulse waveforms from pixelated CdZnTe detectors. Characteristic gamma-ray lines from inelastic neutron scattering were also observed.

On the neutron slowing-down in moderators

Energy Technology Data Exchange (ETDEWEB)

Caldeira, Alexandre D., E-mail: alexdc@ieav.cta.br [Instituto de Estudos Avançados (IEAV), São José dos Campos, SP (Brazil). Divisão de Energia Nuclear

2017-07-01

Neutron slowing-down is a very important subject to be considered in several areas of nuclear energy application, such as thermal nuclear reactors, nuclear medicine, radiological protection, detectors design and so on. Moderator materials are the responsible to perform this task and among the neutron induced cross sections, the elastic scattering cross section is the main nuclear interaction in this case. At thermal neutron energies, the moderator molecular or crystalline structure become important and dependent on the moderator phase, gas, liquid, or solid, its cross sections and, consequently, the angular and energy distributions of the scattered neutron are affected. The procedures used for generating correctly moderators cross sections at thermal neutron energies from evaluated nuclear data files utilizing the NJOY system are addressed. (author)

Alanine and TLD coupled detectors for fast neutron dose measurements in neutron capture therapy (NCT)

Energy Technology Data Exchange (ETDEWEB)

Cecilia, A.; Baccaro, S.; Cemmi, A. [ENEA-FIS-ION, Casaccia RC, Via Anguillarese 301, 00060 Santa Maria di Galeria, Rome (Italy); Colli, V.; Gambarini, G. [Dept. of Physics of the Univ., INFN, Via Celoria 16, 20133 Milan (Italy); Rosi, G. [ENEA-FIS-ION, Casaccia RC, Via Anguillarese 301, 00060 Santa Maria di Galeria, Rome (Italy); Scolari, L. [Dept. of Physics of the Univ., INFN, Via Celoria 16, 20133 Milan (Italy)

2004-07-01

A method was investigated to measure gamma and fast neutron doses in phantoms exposed to an epithermal neutron beam designed for neutron capture therapy (NCT). The gamma dose component was measured by TLD-300 [CaF{sub 2}:Tm] and the fast neutron dose, mainly due to elastic scattering with hydrogen nuclei, was measured by alanine dosemeters [CH{sub 3}CH(NH{sub 2})COOH]. The gamma and fast neutron doses deposited in alanine dosemeters are very near to those released in tissue, because of the alanine tissue equivalence. Couples of TLD-300 and alanine dosemeters were irradiated in phantoms positioned in the epithermal column of the Tapiro reactor (ENEA-Casaccia RC). The dosemeter response depends on the linear energy transfer (LET) of radiation, hence the precision and reliability of the fast neutron dose values obtained with the proposed method have been investigated. Results showed that the combination of alanine and TLD detectors is a promising method to separate gamma dose and fast neutron dose in NCT. (authors)

SFERXS, Photoabsorption, Coherent, Incoherent Scattering Cross-Sections Function for Shielding

International Nuclear Information System (INIS)

Legarda, F.; Mtz de la Fuente, O.; Herranz, M.

2002-01-01

Description of program or function: The use of electromagnetic radiation cross-sections in radiation shielding calculations and more generally in transport theory applications actually requires an interpolation between values which are tabulated for certain values of the energy. In order to facilitate this process and to reduce the computer memory requirements, we have developed, by a least squares method, a set of functions which represents the cross-sections for the photoelectric absorption, the coherent (Rayleigh) and the incoherent (Compton) scattering (1). For this purpose we have accepted as true values the ones tabulated by Storm and Israel (2) for the photoeffect, by Hubbell et Al. (3) for the incoherent scattering and by Hubbell and Overbo (4) for the coherent scattering

Incoherently combining logarithmic aspheric lenses for extended depth of field.

Science.gov (United States)

Chu, Kaiqin; George, Nicholas; Chi, Wanli

2009-10-01

We describe a method for combining concentric logarithmic aspheric lenses in order to obtain an extended depth of field. Substantial improvement in extending the depth of field is obtained by carefully controlling the optical path difference among the concentric lenses so that their outputs combine incoherently. The system is analyzed through diffraction theory and the point spread function is shown to be highly invariant over a long range of object distances. After testing the image performance on a three-dimensional scene, we found that the incoherently combined logarithmic aspheres can provide a high-quality image over an axial distance corresponding to a defocus of +/- 14(lambda/4). Studies of the images of two-point objects are presented to illustrate the resolution of these lenses.

Neutron spectral modulation as a new thermal neutron scattering technique. Pt. 1

International Nuclear Information System (INIS)

Ito, Y.; Nishi, M.; Motoya, K.

1982-01-01

A thermal neutron scattering technique is presented based on a new idea of labelling each neutron in its spectral position as well as in time through the scattering process. The method makes possible the simultaneous determination of both the accurate dispersion relation and its broadening by utilizing the resolution cancellation property of zero-crossing points in the cross-correlated time spectrum together with the Fourier transform scheme of the neutron spin echo without resorting to the echoing. The channel Fourier transform applied to the present method also makes possible the determination of the accurate direct energy scan profile of the scattering function with a rather broad incident neutron wavelength distribution. Therefore the intensity sacrifice for attaining high accurarcy is minimized. The technique is used with either a polarized or unpolarized beam at the sample position with no precautions against beam depolarization at the sample for the latter case. Relative time accurarcy of the order of 10 -3 to 10 -4 may be obtained for the general dispersion relation and for the quasi-elastic energy transfers using correspondingly the relative incident neutron wavelength spread of 10 to 1% around an incident neutron energy of a few meV. (orig.)

Ultrafast Dephasing and Incoherent Light Photon Echoes in Organic Amorphous Systems

Science.gov (United States)

Yano, Ryuzi; Matsumoto, Yoshinori; Tani, Toshiro; Nakatsuka, Hiroki

1989-10-01

Incoherent light photon echoes were observed in organic amorphous systems (cresyl violet in polyvinyl alcohol and 1,4-dihydroxyanthraquinone in polymethacrylic acid) by using temporally-incoherent nanosecond laser pulses. It was found that an echo decay curve of an organic amorphous system is composed of a sharp peak which decays very rapidly and a slowly decaying wing at the tail. We show that the persistent hole burning (PHB) spectra were reproduced by the Fourier-cosine transforms of the echo decay curves. We claim that in general, we must take into account the multi-level feature of the system in order to explain ultrafast dephasing at very low temperatures.

Nonlinear propagation of a spatially incoherent laser beam: self-induced smoothing and reduction of scattering instabilities

International Nuclear Information System (INIS)

Maximov, A.V.; Ourdev, I.G.; Rozmus, W.; Capjack, C.E.; Mounaix, Ph.; Huller, S.; Pesme, D.; Tikhonchuk, V.T.; Divol, L.

2000-01-01

It is shown that plasma-induced angular spreading and spectral broadening of a spatially incoherent laser beam correspond to increased spatial and temporal incoherence of the laser light. The spatial incoherence is characterized by an effective beam f-number, decreasing in space along the direction of light propagation. Plasma-induced beam smoothing can influence laser-plasma interaction physics. In particular, decreasing the correlation time of the propagating laser light may dramatically reduce the levels of backward stimulated Brillouin and Raman scattering inside the plasma. Also, the decrease of the laser beam effective f-number reduces the reflectivity of backward stimulated Brillouin scattering. (authors)

Study of the elastic scattering and of the (p,n) charge exchange reaction with neutron-rich light exotic beams; Etude de la diffusion elastique et de la reaction d`echange de charge (p,n) avec des faisceaux exotiques legers riches en neutrons

Energy Technology Data Exchange (ETDEWEB)

Cortina Gil, D.

1996-07-05

We have measured at GANIL, with the high resolution spectrometer SPEG, the elastic scattering of several neutron rich secondary beams ({sup 6}He, {sup 10}Be and {sup 11}Be) on a polypropylene target and the charge exchange reaction p({sup 6}He, {sup 6}Li)n. These exotic beams were produced by nuclear fragmentation and re-focalized with the SISSI device (superconducting solenoids). The signature of a halo structure in these nuclei has been analysed. Special attention has been paid to several aspects of the associated calculations namely, the proton and neutron density distributions and the small binding energy for the last nucleons in these exotic nuclei. Break-up mechanisms are seen to play an important role in these nuclei. 100 refs.

Measurement of leakage neutron spectra for Tungsten with D-T neutrons and validation of evaluated nuclear data

International Nuclear Information System (INIS)

Zhang, S.; Chen, Z.; Nie, Y.; Wada, R.; Ruan, X.; Han, R.; Liu, X.; Lin, W.; Liu, J.; Shi, F.; Ren, P.; Tian, G.; Luo, F.; Ren, J.; Bao, J.

2015-01-01

Highlights: • Evaluated data for Tungsten are validated by integral experiment. • Leakage neutron spectra from the irradiation of D-T neutrons on Tungsten are measured at 60° and 120° by using a time-of-flight method. • The measured results are compared to the MCNP-4C calculated ones with evaluated data of the different libraries. - Abstract: Integral neutronics experiments have been investigated at Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS) in order to validate evaluated nuclear data related to the design of Chinese Initiative Accelerator Driven Systems (CIADS). In the present paper, the accuracy of evaluated nuclear data for Tungsten has been examined by comparing measured leakage neutron spectra with calculated ones. Leakage neutron spectra from the irradiation of D-T neutrons on Tungsten slab sample were experimentally measured at 60° and 120° by using a time-of-flight method. Theoretical calculations are carried out by Monte Carlo neutron transport code MCNP-4C with evaluated nuclear data of the ADS-2.0, ENDF/B-VII.0, ENDF/B-VII.1, JENDL-4.0 and CENDL-3.1 libraries. From the comparisons, it is found that the calculations with ADS-2.0 and ENDF/B-VII.1 give good agreements with the experiments in the whole energy regions at 60°, while a large discrepancy is observed at 120° in the elastic scattering peak, caused by a slight difference in the oscillation pattern of the elastic angular distribution at angles larger than 20°. However, the calculated spectra using data from ENDF/B-VII.0, JENDL-4.0 and CENDL-3.1 libraries showed larger discrepancies with the measured ones, especially around 8.5–13.5 MeV. Further studies are presented for these disagreements

Critical opalescence of neutrons in nonuniform liquid in the gravitation field

International Nuclear Information System (INIS)

Sugakov, V.I.; Chalyj, A.V.; Chernenko, L.M.

1991-01-01

Single elastic scattering of neutrons has been investigated in a liquid near the critical point. Double differential cross sections of neutron scattering are obtained in such a system with allowance for the gravitational effect and in various approximation for the pair correlation function of density fluctuations

Hydrostatic pressure cells development for X-ray and neutron experiments

International Nuclear Information System (INIS)

Passamai Junior, Jose Luis

2010-01-01

It was developed and built two pressure cell original models in order to be applied in X-ray elastic scattering (X-ray diffraction), X-ray absorption and neutron scattering experiments (neutron diffraction) under hydrostatic pressure. For the first two experimental cases, where X-ray beam is used, the pressure cell built with two B 4 C anvil mounted in a CuBe body. The B 4 C anvil was prepared at CTA research center in order to present an enhanced X-ray transparence and hardness. The special detail and advantage of the CuBe cell with B 4 C anvil is that this cell can be also used to measure de AC magnetic susceptibility in situ. This special characteristic is highlight as new concept of labeled here as multipurpose pressure cell. A second type of cell pressure was developed in order to be used in neutron elastic scattering experiments, specific in neutron diffraction experiments. The neutron cell pressure was developed using carbon fibers composite to improve the mechanical resistance a cylindrical geometry. The B 4 C pressure cells were available to researches in LNLS. The neutron pressure cell was given to research staff of IPEN Nuclear Reactor. This work show details and draws of these two types of hydrostatic pressure cells. (author)

Scattered and (n,2n) neutrons as a measure of areal density in ICF capsules

CERN Document Server

Wilson, D C; Disdier, L; Houry, M; Bourgade, J L; Murphy, T J

2002-01-01

The fraction of low-energy neutrons created from 14 MeV neutrons by elastic scattering and (n,2n) reactions on D and T has been proposed as a measure of the areal density (radial integral of density) of ICF targets. In simple situations the fraction of neutrons between 9.4 (the upper energy of T+T neutrons) and 13 MeV (below the Doppler broadened 14.1 MeV peak) is proportional to the at the time of neutron production. This ratio does not depend upon the temperature of the fuel, as does the number of reaction-in-flight neutrons. The ratio of neutrons elastically scattered at a specific energy (e.g. 13 MeV) to the total number of neutrons can be measured along different lines of sight. The ratio of two perpendicular measurements provides a quantitative measure of asymmetry. A detector can be placed inside the target chamber to measure these low-energy neutrons. If it is close enough to the target that measurements are made before the 14 MeV neutrons reach the chamber wall, gamma rays can be a negligible back...

Inelastic scattering of 275 keV neutrons by silver

International Nuclear Information System (INIS)

Litvinsky, L.L.; Zhigalov, Ya.A.; Krivenko, V.G.; Purtov, O.A.; Sabbagh, S.

1997-01-01

Neutron total, elastic and inelastic scattering cross-scattering of Ag at the E n = 275 KeV neutron energy were measured by using the filtered neutron beam of the WWR-M reactor in Kiev. The d-neutron strength function S n2 of Ag was determined from the analysis of all available data in the E n ≤ keV energy region on neutron inelastic scattering cross-sections with excitation of the first isomeric levels I π m = 7/2 + , E m ∼ 90 keV of 107,109 Ag: S n2 = (1.03 ± 0.19) · 10 -4 . (author). 10 refs, 3 figs

Phase diagram of incoherently driven strongly correlated photonic lattices

Science.gov (United States)

Biella, Alberto; Storme, Florent; Lebreuilly, José; Rossini, Davide; Fazio, Rosario; Carusotto, Iacopo; Ciuti, Cristiano

2017-08-01

We explore theoretically the nonequilibrium photonic phases of an array of coupled cavities in presence of incoherent driving and dissipation. In particular, we consider a Hubbard model system where each site is a Kerr nonlinear resonator coupled to a two-level emitter, which is pumped incoherently. Within a Gutzwiller mean-field approach, we determine the steady-state phase diagram of such a system. We find that, at a critical value of the intercavity photon hopping rate, a second-order nonequilibrium phase transition associated with the spontaneous breaking of the U(1 ) symmetry occurs. The transition from an incompressible Mott-like photon fluid to a coherent delocalized phase is driven by commensurability effects and not by the competition between photon hopping and optical nonlinearity. The essence of the mean-field predictions is corroborated by finite-size simulations obtained with matrix product operators and corner-space renormalization methods.

Fast-neutron total and scattering cross sections of 103Rh

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-07-01

Fast-neutron total cross sections of 103 Rh are measured with 30 to 50 keV resolutions from 0.7 to 4.5 MeV. Differential elastic- and inelastic-scattering cross sections are measured from 1.45 to 3.85 MeV. Scattered-neutron groups corresponding to excited levels at 334 +- 13, 536 +- 7, 648 +- 25, 796 +- 20, 864 +- 22, 1120 +- 22, 1279 +- 50, 1481 +- 27, 1683 +- 39, 1840 +- 79, 1991 +- 71 and 2050 (tentative) keV are observed. An optical-statistical model is derived from the elastic-scattering results. The experimental values are compared with comparable quantities given in the ENDF/B-V evaluation

Seismic soil-structure interaction with consideration of spatial incoherence of seismic ground motions: A case study

Energy Technology Data Exchange (ETDEWEB)

Tseng, Wen S., E-mail: wen.tseng@rizzoassoc.com [Paul C. Rizzo Associates, Inc., Western Region, 2201 Broadway, Suite 400, Oakland, CA 94612 (United States); Lilhanand, Kiat; Hamasaki, Don; Garcia, Julio A. [Paul C. Rizzo Associates, Inc., Western Region, 2201 Broadway, Suite 400, Oakland, CA 94612 (United States); Srinivasan, Ram [AREVA, NP, Inc., 6399 San Ignacio Avenue, San Jose, CA 95119 (United States)

2014-04-01

This paper presents a case study of seismic soil-structure interaction (SSI) analysis with consideration of spatial incoherence of seismic input ground motions. The SSI analyses were performed using the SASSI computer program for the Auxiliary Control Building (ACB) structure of an existing nuclear power plant on a hard rock site located in the Center and Eastern United States (CEUS) region. The incoherent seismic input motions for the hard rock site used for the analyses were generated using the computer program INCOH that works together with SASSI. The objective of the analyses was to generate maximum seismic response parameters for assessment of potential impact of newly developed site-specific (ground motion) response spectra (SSRS) on the seismic design of the ACB and potential benefits that could be gained by considering spatial incoherence of seismic input motions. Maximum seismic response values for selected response parameters of interest were generated with both SSRS-compatible coherent and incoherent seismic input motions. Comparisons were made of the corresponding maximum response parameter values and in-structure (acceleration) response spectra (ISRS) generated for both the coherent and incoherent motion inputs. These comparisons indicate that, by incorporating incoherence of ground motions in the seismic input, the maximum response values reduces and the ISRS peak amplitudes in the high frequency range (>10 Hz) also reduce from the corresponding response values resulting from the coherent motion input. The amount of ISRS-amplitude reduction increases as the spectral frequency increases, as expected. Such reductions can be as much as 20–50%. This case study demonstrates that, for a CEUS hard rock site where relatively high high-frequency in the seismic input response spectra exist, consideration of spatial incoherence of input motions would result in substantial benefits in reducing the high-frequency seismic responses. Such benefits are especially

Quality factors for monoenergetic neutrons

International Nuclear Information System (INIS)

Cross, W.G.; Ing, H.

1984-01-01

Mean quality factors anti Q(E/sub n/), for the dose resulting from first interactons of monoenergetic neutrons in tissue, have been calculated at energies from thermal to 14.7 MeV. Knowledge of these values, along with kerma factors, allows the calculation of the heavy-particle dose equivalent for any known neutron spectrum in tissue. The partial quality factors for the dose delivered by C, N, and O elastic and inelastic recoils are found to be virtually independent of the scattering angular distributions and are given by simple expressions

Elastic Coulomb breakup of 34Na

Science.gov (United States)

Singh, G.; Shubhchintak, Chatterjee, R.

2016-08-01

Background: 34Na is conjectured to play an important role in the production of seed nuclei in the alternate r -process paths involving light neutron rich nuclei very near the β -stability line, and as such, it is important to know its ground state properties and structure to calculate rates of the reactions it might be involved in, in the stellar plasma. Found in the region of `island of inversion', its ground state might not be in agreement with normal shell model predictions. Purpose: The aim of this paper is to study the elastic Coulomb breakup of 34Na on 208Pb to give us a core of 33Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of 34Na. Method: A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of 34Na on 208Pb at 100 MeV/u. The triple differential cross section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum, and angular distributions as well as the average momenta, along with the energy-angular distributions. Results: The total one neutron removal cross section is calculated to test the possible ground state configurations of 34Na. The average momentum results along with energy-angular calculations indicate 34Na to have a halo structure. The parallel momentum distributions with narrow full widths at half-maxima signify the same. Conclusion: We have attempted to analyze the possible ground state configurations of 34Na and in congruity with the patterns in the `island of inversion' conclude that even without deformation, 34Na should be a neutron halo with a predominant contribution to its ground state most probably coming from 33Na(3 /2+)⊗ 2 p3 /2ν configuration. We also surmise that it would certainly be useful and rewarding to test our

Incoherent scatter studies of upper atmosphere dynamics and coding technique

International Nuclear Information System (INIS)

Haeggstroem, Ingemar.

1990-09-01

Observations by the EISCAT incoherent scatter radar are used to study the dynamics of the auroral upper atmosphere. The study describes some effects of the strong plasma convection occurring at these latitudes and a new coding technique for incoherent scatter radars. A technique to determine the thermospheric neutral wind from incoherent scatter measurements is described. Simultaneous Fabry-Perot interferometer measurements of the wind are compared with those derived from the radar data. F-region electron density depletions in the afternoon/evening sector of the auroral zone, identified as the main ionospheric trough, are investigated. In a statistical study, based on wide latitude scanning experiment made at solar minimum, the trough appearance at a given latitude is compared to the geomagnetic index K p , and an empirical model predicting the latitude of the trough is proposed. Detailed studies, using different experiment modes, show that the equatorward edge of the auroral oval is co-located of up to 1 degree poleward of the trough minimum, which in turn is co-located with the peak convective electric field, with its boundary 1 degree - 2 degree equatorward of the trough minimum. It is shown that the F-region ion composition changes from pure 0 + to molecular ion dominated (NO + /O 2 + ) as the trough moves into the region probed by the radar. In a special case, where a geomagnetic sudden impulse caused an expansion of the plasma convection pattern, the equatorward trough progression is studied together with ionosonde measurements. A new coding technique for incoherent scatter radar measurement is introduced and described. The method, called alternating codes, provides significantly more accurate estimates of the plasma parameters than can be obtained by frequency commutated multipulse measurements. Simple explanations of the method are given as well as a precise definition. Two examples of application of the alternating codes are presented, showing the high

Coherence and incoherence collective behavior in financial market

Science.gov (United States)

Zhao, Shangmei; Xie, Qiuchao; Lu, Qing; Jiang, Xin; Chen, Wei

2015-10-01

Financial markets have been extensively studied as highly complex evolving systems. In this paper, we quantify financial price fluctuations through a coupled dynamical system composed of phase oscillators. We find that a Financial Coherence and Incoherence (FCI) coexistence collective behavior emerges as the system evolves into the stable state, in which the stocks split into two groups: one is represented by coherent, phase-locked oscillators, the other is composed of incoherent, drifting oscillators. It is demonstrated that the size of the coherent stock groups fluctuates during the economic periods according to real-world financial instabilities or shocks. Further, we introduce the coherent characteristic matrix to characterize the involvement dynamics of stocks in the coherent groups. Clustering results on the matrix provides a novel manifestation of the correlations among stocks in the economic periods. Our analysis for components of the groups is consistent with the Global Industry Classification Standard (GICS) classification and can also figure out features for newly developed industries. These results can provide potentially implications on characterizing the inner dynamical structure of financial markets and making optimal investment into tragedies.

The effect of the precipitation of coherent and incoherent precipitates on the ductility and toughness of high-strength steel

International Nuclear Information System (INIS)

Hamano, R.

1993-01-01

The effect of the coexistence of coherent and incoherent precipitates, such as M 2 C and NiAl, on the ductility and plane strain fracture toughness of 5 wt pct Ni-2 wt pct Al-based high-strength steels was studied. In order to disperse coherent and incoherent precipitates, the heat treatments were carried out as follows: (a) austenitizing at 1373 K, (b) tempering at 1023 or 923 K for dispersing the incoherent precipitates of M 2 C and NiAl, and then (c) aging at 843 K for 2.4 ks to disperse the coherent precipitate of NiAl into the matrix, which contains incoherent precipitates, such as M 2 C and NiAl. The results were obtained as follows: (a) when the strengthening precipitates consist of coherent ones, such as M 2 C and/or NiAl, the ductility and toughness are extremely low, and (b) when the strengthening precipitates consist of coherent and incoherent precipitates, such as M 2 C and NiAl, the ductility and fracture toughness significantly increase with no loss in strength. It is shown that the coexistence of coherent and incoherent precipitates increases homogeneous deformation, thus preventing local strain concentration and early cleavage cracking. Accordingly, the actions of coherent precipitates in strengthening the matrix and of incoherent precipitates in promoting, homogeneous deformation can be expected to increase both the strength and toughness of the material

Neutron total scattering cross sections of elemental antimony

Energy Technology Data Exchange (ETDEWEB)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-11-01

Neutron total cross sections are measured from 0.8 to 4.5 MeV with broad resolutions. Differential-neutron-elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at intervals of 50 to 200 keV and at scattering angles distributed between 20 and 160 degrees. Lumped-level neutron-inelastic-scattering cross sections are measured over the same angular and energy range. The exPerimental results are discussed in terms of an optical-statistical model and are compared with respective values given in ENDF/B-V.

Neutron total scattering cross sections of elemental antimony

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-11-01

Neutron total cross sections are measured from 0.8 to 4.5 MeV with broad resolutions. Differential-neutron-elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at intervals of 50 to 200 keV and at scattering angles distributed between 20 and 160 degrees. Lumped-level neutron-inelastic-scattering cross sections are measured over the same angular and energy range. The exPerimental results are discussed in terms of an optical-statistical model and are compared with respective values given in ENDF/B-V

Evaluation of neutron nuclear data for 249Cf

International Nuclear Information System (INIS)

Zhou Delin; Yu Baosheng; Yuan Hanrong; Liu Tong; Zhang Jin; Su Zongdi; Yan Shiwei; Wang Cuilan; Zhang Jingshang

1992-01-01

A complete set of neutron nuclear data from 10 -5 eV to 20 MeV in ENDF/B-6 format has been evaluated for 249 Cf based on measured data, systematics predications and model theory calculations. The evaluated quantities are the total, elastic and inelastic scattering, fission, capture, (n,2n), (n,3n) reaction cross sections, the resolved and unresolved resonance parameters, the angular and energy distributions of emitted neutrons and the average number of neutrons emitted per fission. The numerical data are available in ENDF/B-6 format

Crystal structure and dynamics of K2-x(NH4)xSeO4 mixed crystals studied by x-ray and neutron scattering

International Nuclear Information System (INIS)

Smirnov, L.S.; Natkaniec, I.; Loose, A.

2006-01-01

The K 2-x (NH 4 ) x SeO 4 mixed crystals have been studied by powder X-ray and neutron diffraction and inelastic incoherent neutron scattering in a wide temperature range from 300 to 16 K. No phase transition is observed in (NH 4 ) 2 SeO 4 in the range from room temperature to 20 K. The reorientation potential barriers of ammonium ions in the K 2-x (NH 4 ) x SeO 4 mixed crystals increase with the increasing concentration of ammonium ions

Rotation of methyl side groups in polymers: A Fourier transform approach to quasielastic neutron scattering. 1: Homopolymers

International Nuclear Information System (INIS)

Arrighi, V.; Higgins, J.S.; Howells, W.S.

1995-01-01

The rotational motion of the ester methyl group in poly(methyl methacrylate) (PMMA) was investigated using quasielastic neutron scattering (QENS). A comparison between the authors results and the QENS data reported in the literature for PMMA-d 5 indicates that the amount of quasielastic broadening is highly dependent upon the energy resolution of the spectrometer. This anomalous behavior is here attributed to the method of analysis, namely, the use of a single rotational frequency. Such a procedure leads to a non-Arrhenius temperature dependence, to a temperature-dependent elastic incoherent structure factor, and to values of rotational frequency which are resolution dependent. They propose an alternative approach to the analysis of the QENS data which accounts for the existence of a distribution of rotational frequencies. The frequency data are Fourier transformed to the time domain, and the intermediate scattering function is fitted using a stretched exponential or Kohlraush-Williams-Watts function. The excellent overlap between data from different spectrometers leaves no doubt on the adequacy of their procedure. Measurements of the ether methyl group rotation in poly(vinyl methyl ether) (PVME) are also reported. The PVME data confirm that the behavior observed for PMMA-d 5 is likely to be a common feature to all polymeric systems

Light output response of EJ-309 liquid organic scintillator to 2.86-3.95 MeV carbon recoil ions due to neutron elastic and inelastic scatter

Science.gov (United States)

Norsworthy, Mark A.; Ruch, Marc L.; Hamel, Michael C.; Clarke, Shaun D.; Hausladen, Paul A.; Pozzi, Sara A.

2018-03-01

We present the first measurements of energy-dependent light output from carbon recoils in the liquid organic scintillator EJ-309. For this measurement, neutrons were produced by an associated particle deuterium-tritium generator and scattered by a volume of EJ-309 scintillator into stop detectors positioned at four fixed angles. Carbon recoils in the scintillator were isolated using triple coincidence among the associated particle detector, scatter detector, and stop detectors. The kinematics of elastic and inelastic scatter allowed data collection at eight specific carbon recoil energies between 2.86 and 3.95 MeV. We found the light output caused by carbon recoils in this energy range to be approximately 1.14% of that caused by electrons of the same energy, which is comparable to the values reported for other liquid organic scintillators. A comparison of the number of scattered neutrons at each angle to a Monte Carlo N-Particle eXtended simulation indicates that the ENDF/B-VII.1 evaluation of differential cross sections for 14.1 MeV neutrons on carbon has discrepancies with the experiment as large as 55%, whereas those reported in the JENDL-4.0u evaluation agree with experiment.

Application of the variational method for calculation of neutron spectra and group constants - Master thesis

International Nuclear Information System (INIS)

Milosevic, M.

1979-01-01

One-dimensional variational method for cylindrical configuration was applied for calculating group constants, together with effects of elastic slowing down, anisotropic elastic scattering, inelastic scattering, heterogeneous resonance absorption with the aim to include the presence of a number of different isotopes and effects of neutron leakage from the reactor core. Neutron flux shape P 3 and adjoint function are proposed in order to enable calculation of smaller size reactors and inclusion of heterogeneity effects by cell calculations. Microscopic multigroup constants were prepared based on the UKNDL data library. Analytical-numerical approach was applied for solving the equations of the P 3 approximation to obtain neutron flux moments and adjoint functions

Double folding model analysis of elastic scattering of halo nucleus ...

Indian Academy of Sciences (India)

carried out which provide valuable insight for improving our understanding of nuclear reactions. One of the interesting aspects is to understand the effect of the halo structure, on elastic scattering cross-sections at near-Coulomb barrier energies in reactions induced by neutron halo nuclei and weakly bound radioactive ...

Optically transparent multiple access networks employing incoherent spectral codes

NARCIS (Netherlands)

Huiszoon, B.

2008-01-01

This Ph.D. thesis is divided into 7 chapters to provide the reader an overview of the main results achieved in di®erent sub-topics of the study towards optically transparent multiple access networks employing incoherent spectral codes taking into account wireless transmission aspects. The work

Evidence for anisotropic polar nanoregions in relaxor Pb(Mg1/3Nb2/3)O3: A neutron study of the elastic constants and anomalous TA phonon damping in PMN

Science.gov (United States)

Stock, C.; Gehring, P. M.; Hiraka, H.; Swainson, I.; Xu, Guangyong; Ye, Z.-G.; Luo, H.; Li, J.-F.; Viehland, D.

2012-09-01

We use neutron inelastic scattering to characterize the acoustic phonons in the relaxor Pb(Mg1/3Nb2/3)O3 (PMN) and demonstrate the presence of a highly anisotropic damping mechanism that is directly related to short-range polar correlations. For a large range of temperatures above Tc˜210 K, where dynamic, short-range polar correlations are present, acoustic phonons propagating along [11¯0] and polarized along [110] (TA2 phonons) are overdamped and softened across most of the Brillouin zone. By contrast, acoustic phonons propagating along [100] and polarized along [001] (TA1 phonons) are overdamped and softened for a more limited range of wave vectors q. The anisotropy and temperature dependence of the acoustic phonon energy linewidth Γ are directly correlated with neutron diffuse scattering cross section, indicating that polar nanoregions are the cause of the anomalous behavior. The damping and softening vanish for q→0, i.e., for long-wavelength acoustic phonons near the zone center, which supports the notion that the anomalous damping is a result of the coupling between the relaxational component of the diffuse scattering and the harmonic TA phonons. Therefore, these effects are not due to large changes in the elastic constants with temperature because the elastic constants correspond to the long-wavelength limit. We compare the elastic constants we measure to those from Brillouin scattering experiments and to values reported for pure PbTiO3. We show that while the values of C44 are quite similar, those for C11 and C12 are significantly less in PMN and result in a softening of (C11-C12) over PbTiO3. The elastic constants also show an increased elastic anisotropy [2C44/(C11-C12)] in PMN versus that in PbTiO3. These results are suggestive of an instability to TA2 acoustic fluctuations in PMN and other relaxor ferroelectrics. We discuss our results in the context of the current debate over the “waterfall” effect and show that they are inconsistent with

Neutron slowing-down time in matter

Energy Technology Data Exchange (ETDEWEB)

Chabod, Sebastien P., E-mail: sebastien.chabod@lpsc.in2p3.fr [LPSC, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut Polytechnique de Grenoble, 38000 Grenoble (France)

2012-03-21

We formulate the neutron slowing-down time through elastic collisions in a homogeneous, non-absorbing, infinite medium. Our approach allows taking into account for the first time the energy dependence of the scattering cross-section as well as the energy and temporal distribution of the source neutron population in the results. Starting from this development, we investigate the specific case of the propagation in matter of a mono-energetic neutron pulse. We then quantify the perturbation on the neutron slowing-down time induced by resonances in the scattering cross-section. We show that a resonance can induce a permanent reduction of the slowing-down time, preceded by two discontinuities: a first one at the resonance peak position and an echo one, appearing later. From this study, we suggest that a temperature increase of the propagating medium in presence of large resonances could modestly accelerate the neutron moderation.

Neutron reflectivity studies of single lipid bilayers supported on planar substrates

International Nuclear Information System (INIS)

Krueger, S.; Orts, W.J.; Berk, N.F.; Majkrzak, C.F.; Koenig, B.W.

1994-01-01

Neutron reflectivity was used to probe the structure of single phosphatidylcholine (PC) lipid bilayers adsorbed onto a planar silicon surface in an aqueous environment. Fluctuations in the neutron scattering length density profiles perpendicular to the silicon/water interface were determined for different lipids as a function of the hydrocarbon chain length. The lipids were studied in both the gel and liquid crystalline phases by monitoring changes in the specularly-reflected neutron intensity as a function of temperature. Contrast variation of the neutron scattering length density was applied to both the lipid and the solvent. Scattering length density profiles were determined using both model-independent and model-dependent fitting methods. During the reflectivity measurements, a novel experimental set-up was implemented to decrease the incoherent background scattering due to the solvent. Thus, the reflectivity was measured to Q ∼ 0.3 Angstrom -1 , covering up to seven orders of magnitude in reflected intensity, for PC bilayers in D 2 O and silicon-matched (38% D 2 O/62% H 2 O) water. The kinetics of lipid adsorption at the silicon/water interface were also explored by observing changes in the reflectivity at low Q values under silicon-matched water conditions

Neutron moderation theory with thermal motion of the moderator nuclei

Energy Technology Data Exchange (ETDEWEB)

Rusov, V.D.; Tarasov, V.A.; Chernezhenko, S.A.; Kakaev, A.A.; Smolyar, V.P. [Odessa National Polytechnic University, Department of Theoretical and Experimental Nuclear Physics, Odessa (Ukraine)

2017-09-15

In this paper we present the analytical expression for the neutron scattering law for an isotropic source of neutrons, obtained within the framework of the gas model with the temperature of the moderating medium as a parameter. The obtained scattering law is based on the solution of the general kinematic problem of elastic scattering of neutrons on nuclei in the L-system. Both the neutron and the nucleus possess arbitrary velocities in the L-system. For the new scattering law we obtain the flux densities and neutron moderation spectra as functions of temperature for the reactor fissile medium. The expressions for the moderating neutrons spectra allow reinterpreting the physical nature of the underlying processes in the thermal region. (orig.)

Yes, The Precautionary Principle Is Incoherent.

Science.gov (United States)

Peterson, Martin

2017-11-01

This article is a reply to Thomas Boyer-Kassem's discussion of my criticism of the precautionary principle published in this journal about a decade ago. Boyer-Kassem does not question the logical validity of the theorem proved in my original article, but he brings up important questions about its scope. He also challenges the plausibility of some of the assumptions on which it is based. In this comment, I argue that each objection can be adequately dealt with. As a decision rule, the precautionary principle is (still) incoherent. © 2017 Society for Risk Analysis.

Neutron cross-sections of deuterium in the energy range 0.0001eV-15MeV

International Nuclear Information System (INIS)

Bazazyants, N.O.; Zabrodskaya, A.S.; Larina, A.F.; Nikolaev, M.N.

1978-08-01

The paper describes the evaluation of deuterium neutron cross-sections, the spectra of neutrons from the reaction D(n,2n)P and the angular distributions of neutrons from this reaction and of neutrons elastically scattered on deuterium. The evaluation results are presented in the SOCRATOR format. The 26-group system of constants for deuterium is also presented. (author)

Incoherent and coherent backscattering of light by a layer of densely packed random medium

Energy Technology Data Exchange (ETDEWEB)

Tishkovets, Victor P. [Institute of Radio Astronomy of NASU, 4 Chervonopraporna Street, Kharkiv 61002 (Ukraine)], E-mail: tishkovets@ira.kharkov.ua

2007-12-15

The problem of light scattering by a layer of densely packed discrete random medium is considered. The theory of light scattering by systems of nonspherical particles is applied to derive equations corresponding to incoherent (diffuse) and interference parts of radiation reflected from the medium. A solution of the system of linear equations describing light scattering by a system of particles is represented by iteration. It is shown that the symmetry properties of the T-matrices and of the translation coefficients for the vector Helmholtz harmonics lead to the reciprocity relation for an arbitrary iteration. This relation is applied to consider the backscattering enhancement phenomenon. Equations expressing the incoherent and interference parts of reflected light from statistically homogeneous and isotropic plane-parallel layer of medium are given. In the exact backscattering direction the relation between incoherent and interference parts is identical to that of sparse media.

Are Ascriptions of Intentionality to the Brain Incoherent?

DEFF Research Database (Denmark)

Presskorn-Thygesen, Thomas

The ascriptions of ‘agency’ or ‘intentionality’ to the brain has long been regarded with suspicion from social scientists and philosophers. In the talk, I will argue that this suspicion is perfectly legitimate and that the standard response from the defenders of cognitive neuroscience is illegiti...... to the brain are conceptually incoherent because it commits a mereological fallacy (Bennett&Hacker 2001, 2007)....

Gravitational waves from freely precessing neutron stars

International Nuclear Information System (INIS)

Jones, D.I.

2001-01-01

The purpose of this study is to assess the likely detectability of gravitational waves from freely precessing neutron stars. We begin by presenting a neutron star model of sufficient complexity to take into account both the elasticity and fluidity of a realistic neutron star. We then examine the effect of internal dissipation (i.e. heat generation within the star) and gravitational radiation reaction on the wobble. This is followed by an examination of various astrophysical scenarios where some mechanism might pump the precessional motion. We estimate the gravitational wave amplitude in these situations. Finally, we conclude that gravitational radiation from freely precessing neutron stars is almost certainly limited to a level undetectable by a LIGO II detector by internal dissipation. (author)

Fast-neutrons incident on rotors: Tantalum

International Nuclear Information System (INIS)

Smith, Alan B.

2005-01-01

Mono-energetic neutrons are elastically and inelastically scattered from elemental tantalum at incident energies of ∼0.3-10.0 MeV. These experimental results are augmented with neutron total-cross-section and additional neutron-scattering data from the literature to form a composite experimental database. The latter is interpreted in the context of optical-statistical and coupled-channels models, including consideration of collective rotations, dispersion effects and other physical properties. The results are compared with those of similar processes in this region of collective nuclei. A regional model is proposed for the interpretation and prediction of such interactions. The model and the experimental results are compared with corresponding values given in ENDF/B-VI

Direct observation of electronic and nuclear ground state splitting in external magnetic field by inelastic neutron scattering on oxidized ferrocene and ferrocene containing polymers

Science.gov (United States)

Appel, Markus; Frick, Bernhard; Elbert, Johannes; Gallei, Markus; Stühn, Bernd

2015-01-01

The quantum mechanical splitting of states by interaction of a magnetic moment with an external magnetic field is well known, e.g., as Zeeman effect in optical transitions, and is also often seen in magnetic neutron scattering. We report excitations observed in inelastic neutron spectroscopy on the redox-responsive polymer poly(vinylferrocene). They are interpreted as splitting of the electronic ground state in the organometallic ferrocene units attached to the polymer chain where a magnetic moment is created by oxidation. In a second experiment using high resolution neutron backscattering spectroscopy we observe the hyperfine splitting, i.e., interaction of nuclear magnetic moments with external magnetic fields leading to sub-μeV excitations observable in incoherent neutron spin-flip scattering on hydrogen and vanadium nuclei.

The ratio Rdp of the quasi-elastic nd → p(nn) to the elastic np → pn charge-exchange process yields at 0 deg over 0.55-2.0 GeV neutron beam energy region: 2. Comparison of the results with the model dependent calculations

International Nuclear Information System (INIS)

Sharov, V.I.; Morozov, A.A.; Shindin, R.A.; Chernykh, E.V.; Nomofilov, A.A.; Strunov, L.N.

2008-01-01

In our previous paper, the new experimental results on ratio R dp of the quasi-elastic charge-exchange yield at 0 Lab d eg for the nd → p + (nn) reaction to the elastic np → pn charge-exchange yield, were presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory of High Energies of the Joint Institute for Nuclear Research at the neutron beam kinetic energies of 0.55, 0.8, 1.0,1.2, 1.4, 1.8 and 2.0 GeV. In this paper, the comparison of these R dp data with the R dp calculations obtained within the impulse approximation by using the invariant amplitude sets from the GW/VPI phase-shift analysis, is made. The calculated R dp values with the set of invariant amplitude data for the elastic np → pn charge exchange at θ p,CM = 0 deg are in a good agreement with the experimental data. It has been confirmed that at θ p,CM = 0 deg the nd → pnn process is caused by the elastic np → pn charge-exchange reaction. Thus, it has been shown that the obtained experimental R dp results can be used for the Delta-Sigma experimental programme to reduce the total ambiguity in the extraction of the amplitude parts

Electric Form Factor of the Neutron

Science.gov (United States)

Feuerbach, Robert

2007-10-01

Recent polarization-based precision measurements of the nucleons' elastic electric form factors have led to surprising results. The measurement of the ratio of the proton's electromagnetic form factors, μpGE^p/GM^p, was found to drop nearly linearly with Q^2 out to at least 5 GeV^2, inconsistent with the older Rosenbluth-type experiments. A recent measurement of GE^n, the neutron's electric form-factor saw GE^n does not fall off as quickly as commonly expected up to Q^2 1.5 GeV^2. Extending this study, a precision measurement of GE^n up to Q^2=3.5 GeV^2 was completed in Hall A at Jefferson Lab. The ratio GE^n/GM^n was measured through the beam-target asymmetry A of electrons quasi-elastically scattered off polarized neutrons in the reaction ^3He(e,e' n). The experiment took full advantage of the electron beam, recent target developments, as well as two detectors new to Jefferson Lab. The measurement used the accelerator's 100% duty-cycle high-polarization (typically 84%) electron beam and a new, hybrid optically-pumped polarized ^3He target which achieved in-beam polarizations in excess of 50%. A medium acceptance (80msr) open-geometry magnetic spectrometer (BigBite) detected the scattered electron, while a geometrically matched neutron detector observed the struck neutron. Preliminary results from this measurement will be discussed and compared to modern calculations of GE^n.

Precise Extraction of the Neutron Magnetic Form Factor from Quasi-elastic 3He(pol)(e(pol),e') at Q2 = 0.1-0.6 (GeV/c)2

International Nuclear Information System (INIS)

Jens-ole Hansen; Brian Anderson; Leonard Auerbach; Todd Averett; William Bertozzi; Tim Black; John Calarco; Lawrence Cardman; Gordon Cates; Zhengwei Chai; Jiang-Ping Chen; Seonho Choi; Eugene Chudakov; Steve Churchwell; G Corrado; Christopher Crawford; Daniel Dale; Alexandre Deur; Pibero Djawotho; Dipangkar Dutta; John Finn; Haiyan Gao; Ronald Gilman; Oleksandr Glamazdin; Charles Glashausser; Walter Gloeckle; Jacek Golak; Javier Gomez; Viktor Gorbenko; F. Hersman; Douglas Higinbotham; Richard Holmes; Calvin Howell; Emlyn Hughes; Thomas Humensky; Sebastien Incerti; Piotr Zolnierczuk; Cornelis De Jager; John Jensen; Xiaodong Jiang; Cathleen Jones; Mark Jones; R Kahl; H Kamada; A Kievsky; Ioannis Kominis; Wolfgang Korsch; Kevin Kramer; Gerfried Kumbartzki; Michael Kuss; Enkeleida Lakuriqi; Meihua Liang; Nilanga Liyanage; John LeRose; Sergey Malov; Demetrius Margaziotis; Jeffery Martin; Kathy McCormick; Robert McKeown; Kevin McIlhany; Zein-Eddine Meziani; Robert Michaels; Greg Miller; Joseph Mitchell; Sirish Nanda; Emanuele Pace; Tina Pavlin; Gerassimos Petratos; Roman Pomatsalyuk; David Pripstein; David Prout; Ronald Ransome; Yves Roblin; Marat Rvachev; Giovanni Salme; Michael Schnee; Charles Seely; Taeksu Shin; Karl Slifer; Paul Souder; Steffen Strauch; Riad Suleiman; Mark Sutter; Bryan Tipton; Luminita Todor; M Viviani; Branislav Vlahovic; John Watson; Claude Williamson; H Witala; Bogdan Wojtsekhowski; Feng Xiong; Wang Xu; Jen-chuan Yeh

2006-01-01

We have measured the transverse asymmetry A T' in the quasi-elastic 3 /rvec He/(/rvec e/,e') process with high precision at Q 2 -values from 0.1 to 0.6 (GeV/c) 2 . The neutron magnetic form factor G M n was extracted at Q 2 -values of 0.1 and 0.2 (GeV/c) 2 using a non-relativistic Faddeev calculation which includes both final-state interactions (FSI) and meson-exchange currents (MEC). Theoretical uncertainties due to the FSI and MEC effects were constrained with a precision measurement of the spin-dependent asymmetry in the threshold region of 3 /rvec He/(/rvec e/,e'). We also extracted the neutron magnetic form factor G M n at Q 2 -values of 0.3 to 0.6 (GeV/c) 2 based on Plane Wave Impulse Approximation calculations

Phenylene ring dynamics in bisphenol-A-polysulfone by neutron scattering

International Nuclear Information System (INIS)

Arrese-Igor, S.; Arbe, A.; Alegria, A.; Colmenero, J.; Frick, B.

2004-01-01

We have investigated the dynamics of phenylene rings in a glassy polysulfone (bisphenol-A-polysulfone) by means of quasielastic neutron scattering. Nowadays it is well known that these molecular motions are directly connected with the mechanical properties of engineering thermoplastics in general. The particular system investigated by us has the advantage that by selective deuteration of the methyl groups, the neutron scattering measured is dominated by the incoherent contribution from the protons in the phenylene rings. In this way, the dynamics of such molecular groups can be experimentally isolated. Two different types of neutron spectrometers: time of flight and backscattering, were used in order to cover a wide dynamic range, which extends from microscopic (10 -13 s) to mesoscopic (10 -9 s) times. Moreover, neutron diffraction experiments with polarization analysis were also carried out in order to characterize the structural features of the sample investigated. Fast oscillations of increasing amplitude with temperature and π-flips are identified for phenylene rings motions. Due to the structural disorder characteristic of the amorphous state, both molecular motions display a broad distribution of relaxation times, which spreads over several orders of magnitude. Based on the results obtained, we propose a model for phenylene rings dynamics, which combines the two kinds of molecular motions identified. This model nicely describes the neutron scattering results in the whole dynamic range investigated

New Insights into the Molecular Dynamics of P3HT:PCBM Bulk Heterojunction: A Time-of-Flight Quasi-Elastic Neutron Scattering Study.

Science.gov (United States)

Guilbert, Anne A Y; Zbiri, Mohamed; Jenart, Maud V C; Nielsen, Christian B; Nelson, Jenny

2016-06-16

The molecular dynamics of organic semiconductor blend layers are likely to affect the optoelectronic properties and the performance of devices such as solar cells. We study the dynamics (5-50 ps) of the poly(3-hexylthiophene) (P3HT): phenyl-C61-butyric acid methyl ester (PCBM) blend by time-of-flight quasi-elastic neutron scattering, at temperatures in the range 250-360 K, thus spanning the glass transition temperature region of the polymer and the operation temperature of an OPV device. The behavior of the QENS signal provides evidence for the vitrification of P3HT upon blending, especially above the glass transition temperature, and the plasticization of PCBM by P3HT, both dynamics occurring on the picosecond time scale.

Note on neutron scattering and the optical model near A = 208

International Nuclear Information System (INIS)

Guenther, P.; Havel, D.; Smith, A.

1976-09-01

Elastic neutron scattering cross sections of 206 Pb, 207 Pb, 208 Pb and 209 Bi are measured at incident neutron energy intervals of approx. 25 keV from 0.6 to 1.0 MeV with resolutions of approx. 25 keV. Optical model parameters are obtained from the energy-averaged experimental results for each of the isotopes. The observed elastic-neutron-scattering distributions and derived parameters for the lead isotopes (doubly magic or neutron holes in the closed shell) tend to differ from those of 209 Bi (doubly closed shell plus a proton). These potentials, derived in the approx. spherical region of A approximately 208, are extrapolated for the analysis of total and scattering cross sections of 238 U introducing only a small N-Z/A dependence and the known deformation of 238 U. Good descriptions of 238 U total cross sections are obtained from a few hundred keV to 10.0 MeV and the prediction of measured scattering distributions in the low MeV region are as suitable as frequently reported with other specially developed potentials

Theoretical calculation and evaluation of complete neutron data for natural niobium

International Nuclear Information System (INIS)

Ma Gonggui; Zou Yiming; Wang Shiming

1990-07-01

An evaluation of a complete neutron nuclear data for natural niobium has been finished on the data measured by experiments up to 1989 and theoretical calculations with program MUP2 and AUJP. The purpose of present work is to build CENDL-2 databank (Chinese Evaluation Nuclear Data Library, second version) which replaces the CENDL-1 (first version of CENDL). The neutron energy for niobium is in the range of 10 -5 eV to 20 MeV. Data of cross section include total, elastic, nonelastic, total elastic, inelastic cross section to 13 discrete levels, inelastic continuum, (n,2n), (n,3n), (n,n ' α) + (n,αn ' ), (n,n ' p) + (n,pn ' ), (n,n ' d) + (n,dn ' ), (n,p), (n,d), (n,t), (n,α) and capture cross sections. Data for MT 251,252 and 253 as well as angular distributions and energy spectra of secondary neutrons are also given

Evaluation of defects induced by neutron radiation in reactor pressure vessels steels

International Nuclear Information System (INIS)

Lopez Jimenez, J.

1978-01-01

We have developed a method for calculating the production of neutron induced defects (depleted zone and crowdions) in ferritic pressure vessel steels for different neutron spectra. They have been analysed both the recoil primary atoms produced by elastic and inelastic collisions with fast neutrons and the ones produced by gamma-ray emission by thermal neutron absorption. Theoretical modelling of increasing in the ductile-brittle transition temperature of ferritic steels has been correlated with experimental data at irradiation temperature up to 400 degree centigree (Author) 15 refs

Green's function approach to neutron flux discontinuities

International Nuclear Information System (INIS)

Saad, E.A.; El-Wakil, S.A.

1980-01-01

The present work is devoted to the presentation of analytical method for the calculation of elastically and inelastically slowed down neutrons in an infinite non-absorbing medium. On the basis of the central limit theory (CLT) and the integral transform technique the slowing down equation including inelastic scattering, in terms of the Green function of elastic scattering, is solved. The Green function is decomposed according to the number of collisions. Placzec discontinuity associated with elastic scattering in addition to two discontinuities due to inelastic scattering are investigated. Numerical calculations for Fe 56 show that the elastic discontinuity produces about 41.8% change in the collision density whilst the ratio of the inelastic collision density discontinuity at qsub(o)sup(+) to the Placzec discontinuity at usub(o) + 1n 1/oc gives 55.7 percent change. (author)

Calculations on neutron irradiation damage in reactor materials

International Nuclear Information System (INIS)

Sone, Kazuho; Shiraishi, Kensuke

1976-01-01

Neutron irradiation damage calculations were made for Mo, Nb, V, Fe, Ni and Cr. Firstly, damage functions were calculated as a function of neutron energy with neutron cross sections of elastic and inelastic scatterings, and (n,2n) and (n,γ) reactions filed in ENDF/B-III. Secondly, displacement damage expressed in displacements per atom (DPA) was estimated for neutron environments such as fission spectrum, thermal neutron reactor (JMTR), fast breeder reactor (MONJU) and two fusion reactors (The Conceptual Design of Fusion Reactor in JAERI and ORNL-Benchmark). then, damage cross section in units of dpa. barn was defined as a factor to convert a given neutron fluence to the DPA value, and was calculated for the materials in the above neutron environments. Finally, production rates of helium and hydrogen atoms were calculated with (n,α) and (n,p) cross sections in ENDF/B-III for the materials irradiated in the above reactors. (auth.)

Incoherently Coupled Grey-Grey Spatial Soliton Pairs in Biased Two-Photon Photovoltaic Photorefractive Crystals

International Nuclear Information System (INIS)

Su Yanli; Jiang Qichang; Ji Xuanmang

2010-01-01

The incoherently coupled grey-grey screening-photovoltaic spatial soliton pairs are predicted in biased two-photon photovoltaic photorefractive crystals under steady-state conditions. These grey-grey screening-photovoltaic soliton pairs can be established provided that the incident beams have the same polarization, wavelength, and are mutually incoherent. The grey-grey screening-photovoltaic soliton pairs can be considered as the united form of grey-grey screening soliton pairs and open or closed-circuit grey-grey photovoltaic soliton pairs. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Dynamics in γ-Fe₂O₃ nanoparticles studied by time-of-flight polarized neutron scattering

DEFF Research Database (Denmark)

Kuhn, L.T.; Lefmann, K.; Klausen, S.N.

2004-01-01

The inelastic neutron-scattering signal from magnetic nanoparticles contains information on magnetic dynamics like superparamagnetic relaxation and collective magnetic excitations. Often another, very broad quasi-elastic component is observed in addition. We have studied this quasi-elastic neutron...... signal from 4 nm ferrimagnetic maghemite (gamma-Fe(2)O(3)) particles, and by means of time-of-flight polarised neutron scattering we have identified the source of (most of) this signal to be water adsorbed at the surface of the nanoparticles. A minor part of the signal has its origin in dynamics...

Depth-resolved incoherent and coherent wide-field high-content imaging (Conference Presentation)

Science.gov (United States)

So, Peter T.

2016-03-01

Recent advances in depth-resolved wide-field imaging technique has enabled many high throughput applications in biology and medicine. Depth resolved imaging of incoherent signals can be readily accomplished with structured light illumination or nonlinear temporal focusing. The integration of these high throughput systems with novel spectroscopic resolving elements further enable high-content information extraction. We will introduce a novel near common-path interferometer and demonstrate its uses in toxicology and cancer biology applications. The extension of incoherent depth-resolved wide-field imaging to coherent modality is non-trivial. Here, we will cover recent advances in wide-field 3D resolved mapping of refractive index, absorbance, and vibronic components in biological specimens.

Seeded Supercontinuum Generation - Modulation Instability Gain, Coherent and Incoherent Rogue Waves

DEFF Research Database (Denmark)

Sørensen, Simon Toft; Larsen, Casper; Møller, Uffe Visbech

2012-01-01

Deterministic supercontinuum can be generated by seeding the modulation instability-induced pulse break-up. We investigate the influence of the modulation instability gain on seeding and demonstrate the generation of coherent and incoherent rogue waves....

Study of an individual neutron dosimeter

International Nuclear Information System (INIS)

Debeauvais, M.; Tripier, J.

1976-01-01

A dosimeter using Kodak LR 115 cellulose nitrate as detecting material was designed. It serves to determine 3 neutron energy ranges. The 6 Li(n,α)t reaction is used for the thermal region, the sensitivity being 0.2mrads to 1 rad for neutron energies between thermal and 0.05eV. The same reaction defines the 0.05eV to 1000eV energy range but the detection system is placed inside a cadmium screen; the sensitivity is 0.2 to 500rads. Finally above 1MeV the neutron reactions used are those on the detector components themselves, i.e. elastic collisions and (nα) reactions on carbon, nitrogen and oxygen nuclei. Detection is possible between 0.7 and 700 rads [fr

Structure and texture investigations by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Vratislav, S [Ceske Vysoke Uceni Technicke, Prague (Czechoslovakia). Fakulta Jaderna a Fysikalne Inzenyrska

1982-01-01

Analysis of the KSN-2 neutron diffractometer parameters helped improve the KSN-2 resolution to 7.5x10/sup -3/. Structure analysis of compounds with elementary cell volume down to 5 nm/sup 3/ can now be performed. Resolution analysis of the neutron powder diffractometer and its conclusions are described, results of the structure determination of zeolites and the magnetic structure determination of perovskites are given. The three-dimensional distribution function and its use in calculating the elastic modulus of aluminium sheets are mentioned.

The synthetic scattering function and application to the design of cold moderators for pulsed neutron sources: a fast response methane based array

International Nuclear Information System (INIS)

Granada, J. R.; Mayer, R. E.; Gillette, V. H.

1997-09-01

The Synthetic Scattering Function (SSF) allows a simple description of the incoherent interaction of slow neutrons with hydrogenous materials. The main advantages of this model reside in the analytical expressions that it produces for double-differential cross sections, energy-transfer kernels, and total cross sections, which in turn permit the fast evaluation of neutron scattering and transport properties. In this work we briefly discuss basic features of the SSF, review some previous applications to a number of moderating materials, and present new Monte Carlo results for a fast time-response moderator concept based on methane at low temperatures. (auth)

The differential elastic scattering of 14.7 MeV neutron from beryllium

International Nuclear Information System (INIS)

Zhang Kun; Cao Jianhua; Wan Dairong; Dai Yunsheng

1995-01-01

A fast neutron associated particle time-of-flight (TOF) spectrometer was used for measuring neutron differential cross sections on beryllium nuclei in this experiment. The total error of the differential cross section is from 7.5% to 11.5% including the statistical error 0.5∼3.5 and the efficiency calibration error 6∼7%. (2 tabs., 1 fig)

Low frequency enzyme dynamics as a function of temperature and hydration: A neutron scattering study

Energy Technology Data Exchange (ETDEWEB)

Kurkal, V. [Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Im Neuenheimer Feld 368, D-69120 Heidelberg (Germany); Daniel, R.M. [Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton (New Zealand); Finney, John L. [Department of Physics and Astronomy, University college, London, Gower Street, London WC1E 6BT, England (United Kingdom); Tehei, M. [Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton (New Zealand); Dunn, R.V. [Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton (New Zealand); Smith, Jeremy C. [Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Im Neuenheimer Feld 368, D-69120 Heidelberg (Germany)], E-mail: biocomputing@iwr.uni-heidelberg.de

2005-10-31

The effect of hydration and temperature on the low-frequency dynamics of the enzyme Pig liver esterase has been investigated with incoherent neutron scattering experiments. The results suggest that at low temperature, increasing hydration results in lower flexibility of the protein. At higher temperatures, systems containing sufficient number of water molecules interacting with the protein exhibit increased flexibility. The environmental force constants indicate that the environment of the protein is more rigid below than it is above the dynamical transition temperature.

On the response of large dams to incoherent seismic excitation

International Nuclear Information System (INIS)

Ramadan, O.; Novak, M.

1993-01-01

An intensive parametric study was conducted to investigate the response of concrete gravity dams to horizontal, spatially variable seismic ground motions. Both segmented dams consisting of separate blocks, or monoliths, and continuous monolithic dams are considered. The study includes the effects of various parameters on system natural frequencies, vibration modes, modal displacement ratios, as well as dam displacements and internal stresses due to spatially variable ground motions. The dam analytical model, and dam response to incoherent ground motions are described. The results show that the dam vibrates almost as a rigid body under the fully correlated waves, but bends and twists significantly under the spatially correlated motions. Dam-foundation interaction magnifies the low frequency components of the dam response, more so for a full reservoir, but decreases the high frequency components. For long dams, the effects of spatially incoherent ground motions are qualitatively different and can be much greater than those due to surface travelling waves. 3 refs., 3 figs

Solution structure of a short dna fragment studied by neutron scattering

DEFF Research Database (Denmark)

Lederer, H.; May, R. P.; Kjems, Jørgen

1986-01-01

-DNA. The neutron scattering curve is well fitted by that of a rigid rod with a length of 44 nm and a diameter of 2 nm. The result were confirmed by quasi-elastic light scattering and analytical centrifugation. The neutron measurements in H2O and D2O buffer reveal a cross-sectional in homogeneity not detected by X...

Measurement of the contribution of neutrons to hadron calorimeter signals

International Nuclear Information System (INIS)

Akchurin, N.; Berntzon, L.; Cardini, A.; Ferrari, R.; Gaudio, G.; Hauptman, J.; Kim, H.; La Rotonda, L.; Livan, M.; Meoni, E.; Paar, H.; Penzo, A.; Pinci, D.; Policicchio, A.; Popescu, S.; Susinno, G.; Roh, Y.; Vandelli, W.; Wigmans, R.

2007-01-01

The contributions of neutrons to hadronic signals from the DREAM calorimeter are measured by analyzing the time structure of these signals. The neutrons, which mainly originate from the evaporation stage of nuclear breakup in the hadronic shower development process, contribute through elastic scattering off protons in the plastic scintillating fibers which provide the dE/dx information in this calorimeter. This contribution is characterized by an exponential tail in the pulse shape, with a time constant of ∼25ns. The relative contribution of neutrons to the signals increases with the distance from the shower axis. As expected, the neutrons do not contribute to the DREAM Cherenkov signals

Neutron Cross section Covariances in the Resonance region: 50,53Cr, 54,57Fe and 60Ni

Energy Technology Data Exchange (ETDEWEB)

Oblozinsky, P.; Cho,Y.-S.; Mattoon,C.M.; Mughabghab,S.F.

2010-11-23

We evaluated covariances in the neutron resonance region for capture and elastic scattering cross sections on minor structural materials, {sup 50,53}Cr, {sup 54,57}Fe and {sup 60}Ni. Use was made of the recently developed covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. Our results of most interest for advanced fuel cycle applications, elastic scattering cross section uncertainties at energies around 100 keV, are on the level of about 7-10%.

A combined neutron scattering and simulation study on bioprotectant systems

Energy Technology Data Exchange (ETDEWEB)

Affouard, F. [Laboratoire de Dynamique et Structure des Materiaux Moleculaires UMR 8024, Universite Lille I - 59655 Villeneuve d' Ascq cedex (France); Bordat, P. [Laboratoire de Dynamique et Structure des Materiaux Moleculaires UMR 8024, Universite Lille I - 59655 Villeneuve d' Ascq cedex (France); Descamps, M. [Laboratoire de Dynamique et Structure des Materiaux Moleculaires UMR 8024, Universite Lille I - 59655 Villeneuve d' Ascq cedex (France); Lerbret, A. [Laboratoire de Dynamique et Structure des Materiaux Moleculaires UMR 8024, Universite Lille I - 59655 Villeneuve d' Ascq cedex (France); Magazu, S. [Dipartimento di Fisica and INFM, Universita di Messina, P.O. Box 55, I-98166 Messina (Italy); Migliardo, F. [Laboratoire de Dynamique et Structure des Materiaux Moleculaires UMR 8024, Universite Lille I - 59655 Villeneuve d' Ascq cedex (France); Dipartimento di Fisica and INFM, Universita di Messina, P.O. Box 55, I-98166 Messina (Italy)], E-mail: fmigliardo@unime.it; Ramirez-Cuesta, A.J. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot (United Kingdom); Telling, M.F.T. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot (United Kingdom)

2005-10-31

The present work shows quasi elastic neutron scattering, neutron spin echo and inelastic neutron scattering results on a class of bioprotectant systems, such as homologous disaccharides (i.e., trehalose and sucrose)/water solutions, as a function of temperature. The whole set of findings indicates a noticeable 'kosmotrope' character of the disaccharides, and in particular of trehalose, which is able to strongly modify both the structural and dynamical properties of water. This superior capability of trehalose can be linked to its higher bioprotective effectiveness in respect with the other disaccharides.

Theory of neutron scattering in disordered alloys

International Nuclear Information System (INIS)

Yussouff, M.; Mookerjee, A.

1984-08-01

A comprehensive theory of thermal neutron scattering in disordered alloys is presented here. We consider in detail the case of substitutional random binary alloy with random changes in mass and force constants; and for all values of the concentration. The cluster CPA formalism in argumented space developed here is free from analytical difficulties for the Green function, performs correct averaging over random atomic scattering lengths and employs a self-consistent medium for the calculations. For easy computation, we describe the graphical representation of the resolvent where the approximation steps can be depicted as closed paths in augmented space. Our results for scattering cross sections, both coherent and incoherent, include new types of terms and these lead to asymmetric line shapes for the coherent scattering. (author)

Atomic form factors, incoherent scattering functions, and photon scattering cross sections

International Nuclear Information System (INIS)

Hubbell, J.H.; Veigele, W.J.; Briggs, E.A.; Brown, R.T.; Cromer, D.T.; Howerton, R.J.

1975-01-01

Tabulations are presented of the atomic form factor, F (α,Z), and the incoherent scattering function, S (x,Z), for values of x (=sin theta/2)/lambda) from 0.005 A -1 to 10 9 A -1 , for all elements A=1 to 100. These tables are constructed from available state-of-the-art theoretical data, including the Pirenne formulas for Z=1, configuration-into action results by Brown using Brown-Fontana and Weiss correlated wavefunctions for Z=2 to 6 non-relativistic Hartree-Fock results by Cromer for Z=7 to 100 and a relativistic K-shell analytic expression for F (x,Z) by Bethe Levinger for x>10 A -1 for all elements Z=2 to 100. These tabulated values are graphically compared with available photon scattering angular distribution measurements. Tables of coherent (Rayleigh) and incoherent (Compton) total scattering cross sections obtained by nummerical integration over combinations of F 2 (x,Z) with the Thomson formula and S (x,Z) with the Klum-Nishina Formual, respectively, are presented for all elements Z=1 to 100, for photon energies 100 eV (lambda=124 A) to 100 MeV (0.000124 A). The incoherent scattering cross sections also include the radiative and double-Compton corrections as given by Mork. Similar tables are presented for the special cases of terminally-bonded hydrogen and for the H 2 molecule, interpolated and extrapolated from values calculated by Stewart et al., and by Bentley and Stewart using Kolos-Roothaan wavefunctions

Influence of neutron irradiation on ferromagnetic metallic glasses

International Nuclear Information System (INIS)

Miglierini, M.; Nasu, Saburo; Sitek, J.

1992-01-01

Transmission 57 Fe Moessbauer spectroscopy is used to study effects of neutron irradiation on magnetic properties of Fe-based ferromagnetic metallic glasses. Elastic stress centers are produced during the process of neutron irradiation as a result of atom mixing. Rearrangement of the atoms causes changes in the average value of the hyperfine field distribution and orientation of the net magnetic moment. They are shown to depend on the composition of the investigated samples. Cr-doped metallic glasses depict transformation from ferromagnetic to paramagnetic state at room temperature after neutron irradiation implying changes in the Curie temperature. Presence of Ni in the samples reduces the effects of radiation damage. (orig.)

Dehydration reactions of gypsum: A neutron and X-ray diffraction study

Science.gov (United States)

Abriel, W.; Reisdorf, K.; Pannetier, J.

1990-03-01

The kinetics of the dehydration of gypsum was investigated by powder diffraction methods. Using the incoherent scattering effect of H with the neutron beam, the background intensity as a measure of the water content was checked in the temperature range 295-623 K. The superposed Bragg peaks yielded four major phases: Gypsum, subhydratesCaSO 4(H 2O) x (1 > x > 0),AIII-CaSO 4, AII-CaSO 4. For the subhydrates a maximum water content of x > = 0.74was determined. A different kinetic was found using Guinier X-ray technique with the heated sample prepared on a thin foil. Only with high local H 2O steam pressure, produced in the comparable larger sample container of the neutron diffraction experiment, could this high H 2O occupation of the subhydrate tunnel structure be found. A topotactic mechanism can describe the phase transitions for this reaction.

Analysis of Quasi-Elastic e-n and e-p Scattering from Deuterium

Science.gov (United States)

Balsamo, Alexander; Gilfoyle, Gerard; CLAS12 Collaboration

2017-09-01

One of Jefferson Lab's goals is to unravel the quark-gluon structure of nuclei. We will use the ratio, R, of electron-neutron to electron-proton scattering on deuterium to probe the magnetic form factor of the neutron. We have developed an end-to-end analysis from simulation to extraction of R in quasi-elastic kinematics for an approved experiment with the CLAS12 detector. We focus on neutrons detected in the CLAS12 calorimeters and protons measured with the CLAS12 forward detector. Events were generated with the Quasi-Elastic Event Generator (QUEEG) and passed through the Monte Carlo code gemc to simulate the CLAS12 response. These simulated events were reconstructed using the latest CLAS12 Common Tools. We first match the solid angle for e-n and e-p events. The electron information is used to predict the path of both a neutron and proton through CLAS12. If both particles interact in CLAS12 the e-n and e-p events have the same solid angle. We select QE events by searching for nuclei near the predicted position. An angular cut between the predicted 3-momentum of the nucleon and the measured value, θpq, separates QE and inelastic events. We will show the simulated R as a function of the four-momentum transfer Q2. Work supported by the University of Richmond and the US Department of Energy.

QR code optical encryption using spatially incoherent illumination

Science.gov (United States)

Cheremkhin, P. A.; Krasnov, V. V.; Rodin, V. G.; Starikov, R. S.

2017-02-01

Optical encryption is an actively developing field of science. The majority of encryption techniques use coherent illumination and suffer from speckle noise, which severely limits their applicability. The spatially incoherent encryption technique does not have this drawback, but its effectiveness is dependent on the Fourier spectrum properties of the image to be encrypted. The application of a quick response (QR) code in the capacity of a data container solves this problem, and the embedded error correction code also enables errorless decryption. The optical encryption of digital information in the form of QR codes using spatially incoherent illumination was implemented experimentally. The encryption is based on the optical convolution of the image to be encrypted with the kinoform point spread function, which serves as an encryption key. Two liquid crystal spatial light modulators were used in the experimental setup for the QR code and the kinoform imaging, respectively. The quality of the encryption and decryption was analyzed in relation to the QR code size. Decryption was conducted digitally. The successful decryption of encrypted QR codes of up to 129  ×  129 pixels was demonstrated. A comparison with the coherent QR code encryption technique showed that the proposed technique has a signal-to-noise ratio that is at least two times higher.

Review of neutron data: 10 to 40 MeV

Energy Technology Data Exchange (ETDEWEB)

Haight, R.C.

1977-04-01

Neutron data are reviewed for incident neutron energies between 10 and 40 MeV. A census of the data shows that there are many gaps in this range and that the existing data are primarily for neutron energies around 14 MeV. Aside from total cross sections, there are few data between 10 and 13 MeV and between 15 and 40 MeV. Examples are presented to show the quality of selected data for total, elastic, inelastic, activation, and charged-particle and gamma-ray production cross sections. The spectra of emitted particles are also discussed.

Review of neutron data: 10 to 40 MeV

International Nuclear Information System (INIS)

Haight, R.C.

1977-04-01

Neutron data are reviewed for incident neutron energies between 10 and 40 MeV. A census of the data shows that there are many gaps in this range and that the existing data are primarily for neutron energies around 14 MeV. Aside from total cross sections, there are few data between 10 and 13 MeV and between 15 and 40 MeV. Examples are presented to show the quality of selected data for total, elastic, inelastic, activation, and charged-particle and gamma-ray production cross sections. The spectra of emitted particles are also discussed

Internal strain measurement using pulsed neutron diffraction at LANSCE

International Nuclear Information System (INIS)

Goldstone, J.A.; Bourke, M.A.M.; Shi, N.

1994-01-01

The presence of residual stress in engineering components can effect their mechanical properties and structural integrity. Neutron diffraction in the only technique that can make nondestructive measurements in the interior of components. By recording the change in crystalline lattice spacings, elastic strains can be measured for individual lattice reflections. Using a pulsed neutron source, all lattice reflections are recorded in each measurement, which allows for easy examination of heterogeneous materials such as metal matrix composites. Measurements made at the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) demonstrate the potential at pulsed sources for in-situ stress measurements at ambient and elevated temperatures

Neutron moisture measurement in materials

International Nuclear Information System (INIS)

Thony, J.L.

1985-01-01

This method is generally used for soil moisture determination but also for moisture in building materials. After a review of neutron interaction with matter (elastic and inelastic scattering, radiative capture and absorption with emission of charged particles) and of the equipment (source, detector and counting), gravimetric and chemical calibration are described and accuracy of measurement is discussed. 5 refs [fr

A New On-the-Fly Sampling Method for Incoherent Inelastic Thermal Neutron Scattering Data in MCNP6

Energy Technology Data Exchange (ETDEWEB)

Pavlou, Andrew Theodore [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ji, Wei [Rensselaer Polytechnic Inst., Troy, NY (United States)

2014-09-02

At thermal energies, the scattering of neutrons in a system is complicated by the comparable velocities of the neutron and target, resulting in competing upscattering and downscattering events. The neutron wavelength is also similar in size to the target's interatomic spacing making the scattering process a quantum mechanical problem. Because of the complicated nature of scattering at low energies, the thermal data files in ACE format used in continuous-energy Monte Carlo codes are quite large { on the order of megabytes for a single temperature and material. In this paper, a new storage and sampling method is introduced that is orders of magnitude less in size and is used to sample scattering parameters at any temperature on-the-fly. In addition to the reduction in storage, the need to pre-generate thermal scattering data tables at fine temperatures has been eliminated. This is advantageous for multiphysics simulations which may involve temperatures not known in advance. A new module was written for MCNP6 that bypasses the current S(α,β) table lookup in favor of the new format. The new on-the-fly sampling method was tested for graphite for two benchmark problems at ten temperatures: 1) an eigenvalue test with a fuel compact of uranium oxycarbide fuel homogenized into a graphite matrix, 2) a surface current test with a \\broomstick" problem with a monoenergetic point source. The largest eigenvalue difference was 152pcm for T= 1200K. For the temperatures and incident energies chosen for the broomstick problem, the secondary neutron spectrum showed good agreement with the traditional S(α,β) sampling method. These preliminary results show that sampling thermal scattering data on-the-fly is a viable option to eliminate both the storage burden of keeping thermal data at discrete temperatures and the need to know temperatures before simulation runtime.

Neutron reflectivity studies of single lipid bilayers supported on planar substrates

Energy Technology Data Exchange (ETDEWEB)

Krueger, S.; Orts, W.J.; Berk, N.F.; Majkrzak, C.F. [National Inst. of Standards and Technology, Gaithersburg, MD (United States); Koenig, B.W. [National Inst. of Health, Bethesda, MD (United States)

1994-12-31

Neutron reflectivity was used to probe the structure of single phosphatidylcholine (PC) lipid bilayers adsorbed onto a planar silicon surface in an aqueous environment. Fluctuations in the neutron scattering length density profiles perpendicular to the silicon/water interface were determined for different lipids as a function of the hydrocarbon chain length. The lipids were studied in both the gel and liquid crystalline phases by monitoring changes in the specularly-reflected neutron intensity as a function of temperature. Contrast variation of the neutron scattering length density was applied to both the lipid and the solvent. Scattering length density profiles were determined using both model-independent and model-dependent fitting methods. During the reflectivity measurements, a novel experimental set-up was implemented to decrease the incoherent background scattering due to the solvent. Thus, the reflectivity was measured to Q {approx} 0.3{Angstrom}{sup -1}, covering up to seven orders of magnitude in reflected intensity, for PC bilayers in D{sub 2}O and silicon-matched (38% D{sub 2}O/62% H{sub 2}O) water. The kinetics of lipid adsorption at the silicon/water interface were also explored by observing changes in the reflectivity at low Q values under silicon-matched water conditions.

Few-Nucleon Research at TUNL: Probing Two- and Three-Nucleon Interactions with Neutrons

Science.gov (United States)

Howell, C. R.; Tornow, W.; Witała, H.

2016-03-01

The central goal of few-nucleon research at the Triangle Universities Nuclear Laboratory (TUNL) is to perform measurements that contribute to advancing ab-initio calculations of nuclear structure and reactions. The program aims include evaluating theoretical treatments of few-nucleon reaction dynamics through strategically comparing theory predictions to data, determining properties of the neutron-neutron interaction that are not accessible in two-nucleon reactions, and searching for evidence of longrange features of three-nucleon interactions, e.g., spin and isospin dependence. This paper will review studies of three- and four-nucleon systems at TUNL conducted using unpolarized and polarized neutron beams. Measurements of neutron-induced reactions performed by groups at TUNL over the last six years are described in comparison with theory predictions. The results are discussed in the context of the program goals stated above. Measurements of vector analyzing powers for elastic scattering in A=3 and A=4 systems, differential cross sections for neutron-deuteron elastic scattering and neutrondeuteron breakup in several final-state configurations are described. The findings from these studies and plans for the coming three years are presented in the context of worldwide activities in this front, in particular, research presented in this session.

Improvements in or relating to neutron beam collimators

International Nuclear Information System (INIS)

Lundberg, D.A.

1975-01-01

Reference is made to collimators suitable for use in neutron therapy equipment. The design of such collimators presents considerable difficulties, since neutrons are very penetrating. Scattering processes are also much more significant with neutrons than with x-rays or γ-rays. A further difficulty is that neutron activation causes some materials to become radioactive, which may present a hazard to users of the equipment. A novel form of collimator is described that overcomes these disadvantages to some extent. It comprises a body containing W for moderating the neutrons by inelastic collision processes, a slow neutron absorbing material intimately mixed with the W for reducing collisions between slow neutrons and the W atoms, a hydrogenous material for further moderating the neutrons to thermal energies by elastic collision processes with H atoms and for absorbing the thermal neutrons by capture processes, and a material having a density of at least 10g/cm 3 for attenuating γ-radiation produced in the hydrogenous material during neutron capture processes. The collimator is of sufficient thickness to be substantially opaque to neutrons of predetermined energy. The slow neutron absorbing material may be B, the hydrogenous material may be polyethylene, and the high density material may be Pb. Alternative methods of using and packing the various materials are described. (U.K.)

Extrapolation of bulk rock elastic moduli of different rock types to high pressure conditions and comparison with texture-derived elastic moduli

Science.gov (United States)

Ullemeyer, Klaus; Lokajíček, Tomás; Vasin, Roman N.; Keppler, Ruth; Behrmann, Jan H.

2018-02-01

In this study elastic moduli of three different rock types of simple (calcite marble) and more complex (amphibolite, micaschist) mineralogical compositions were determined by modeling of elastic moduli using texture (crystallographic preferred orientation; CPO) data, experimental investigation and extrapolation. 3D models were calculated using single crystal elastic moduli, and CPO measured using time-of-flight neutron diffraction at the SKAT diffractometer in Dubna (Russia) and subsequently analyzed using Rietveld Texture Analysis. To define extrinsic factors influencing elastic behaviour, P-wave and S-wave velocity anisotropies were experimentally determined at 200, 400 and 600 MPa confining pressure. Functions describing variations of the elastic moduli with confining pressure were then used to predict elastic properties at 1000 MPa, revealing anisotropies in a supposedly crack-free medium. In the calcite marble elastic anisotropy is dominated by the CPO. Velocities continuously increase, while anisotropies decrease from measured, over extrapolated to CPO derived data. Differences in velocity patterns with sample orientation suggest that the foliation forms an important mechanical anisotropy. The amphibolite sample shows similar magnitudes of extrapolated and CPO derived velocities, however the pattern of CPO derived velocity is closer to that measured at 200 MPa. Anisotropy decreases from the extrapolated to the CPO derived data. In the micaschist, velocities are higher and anisotropies are lower in the extrapolated data, in comparison to the data from measurements at lower pressures. Generally our results show that predictions for the elastic behavior of rocks at great depths are possible based on experimental data and those computed from CPO. The elastic properties of the lower crust can, thus, be characterized with an improved degree of confidence using extrapolations. Anisotropically distributed spherical micro-pores are likely to be preserved, affecting

Interfacial Energy and Fine Defect Structures for Incoherent Films

OpenAIRE

Cermelli, Paolo; Gurtin, Morton E.; Leoni, Giovanni

1999-01-01

This note summarizes recent results in which modern techniques of the calculus of variations are used to obtain qualitative features of film-substrate interfaces for a broad class of interfacial energies. In particular, we show that the existence of a critical thickness for incoherency and the formation of interfacial dislocations depend strongly on the convexity and smoothness of the interfacial energy function.

Dynamics of biopolymers on nanomaterials studied by quasielastic neutron scattering and MD simulations

Science.gov (United States)

Dhindsa, Gurpreet K.

hydrated and dry beta-Casein as a function of temperature, to study the effect of hydration on their flexibility. The Elastic Incoherent Structure Factor (EISF) in the energy domain reveals the fraction of hydrogen atoms participating in motion in a sphere of diffusion. In the time domain analysis, a logarithmic-like decay is observed in the range of picosecond to nanosecond (beta-relaxation time) in the dynamics of hydrated beta-Casein. Our temperature dependent QENS experiments provide evidence that lack of secondary structure in beta-Casein results in higher flexibility in its dynamics and easier reversible thermal unfolding compared to other rigid biomolecules. Lastly, we studied the domain motion of IPPase protein by Neutron Spin Echo Spectroscopy (NSE). We found that decrease in diffusion coefficient belongs to domain motion of IPPase. Moreover, Rg is varied by temperature and concentration.

Determination of the thermospheric neutral wind from incoherent scatter radar measurements

International Nuclear Information System (INIS)

Haeggstroem, I.; Murdin, J.; Rees, D.

1984-11-01

Measurements made by the EISCAT UHF incoherent scatter radar are used to derive thermospheric winds. The derived wind is compared to Fabry-Perot interferometer measurements of the neutral wind made simultaneously. The uncertainties in the radar derived wind are discussed. (author)

Fast-neutron total and scattering cross sections of niobium

Energy Technology Data Exchange (ETDEWEB)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-07-01

Neutron total cross sections of niobium were measured from approx. = 0.7 to 4.5 MeV at intervals of less than or equal to 50 keV with broad resolution. Differential-elastic-scattering cross sections were measured from approx. = 1.5 to 4.0 MeV at intervals of 0.1 to 0.2 MeV and at 10 to 20 scattering angles distributed between approx. = 20 and 160 degrees. Inelastically-scattered neutrons, corresponding to the excitation of levels at: 788 +- 23, 982 +- 17, 1088 +- 27, 1335 +- 35, 1504 +- 30, 1697 +- 19, 1971 +- 22, 2176 +- 28, 2456 +- (.), and 2581 +- (.) keV, were observed. An optical-statistical model, giving a good description of the observables, was deduced from the measured differential-elastic-scattering cross sections. The experimental-results were compared with the respective evaluated quantities given in ENDF/B-V.

Fast-neutron total and scattering cross sections of niobium

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.; Whalen, J.F.

1982-07-01

Neutron total cross sections of niobium were measured from approx. = 0.7 to 4.5 MeV at intervals of less than or equal to 50 keV with broad resolution. Differential-elastic-scattering cross sections were measured from approx. = 1.5 to 4.0 MeV at intervals of 0.1 to 0.2 MeV and at 10 to 20 scattering angles distributed between approx. = 20 and 160 degrees. Inelastically-scattered neutrons, corresponding to the excitation of levels at: 788 +- 23, 982 +- 17, 1088 +- 27, 1335 +- 35, 1504 +- 30, 1697 +- 19, 1971 +- 22, 2176 +- 28, 2456 +- (.), and 2581 +- (.) keV, were observed. An optical-statistical model, giving a good description of the observables, was deduced from the measured differential-elastic-scattering cross sections. The experimental-results were compared with the respective evaluated quantities given in ENDF/B-V

Measured and evaluated neutron cross sections of elemental bismuth

International Nuclear Information System (INIS)

Smith, A.; Guenther, P.; Smith, D.; Whalen, J.; Howerton, R.

1980-04-01

Neutron total cross sections of elemental bismuth are measured with broad resolution from 1.2 to 4.5 MeV to accuracies of approx. = 1%. Neutron-differential-elastic-scattering cross sections of bismuth are measured from 1.5 to 4.0 MeV at incident neutron energy intervals of approx.< 0.2 MeV over the scattered-neutron angular range approx. = 20 to 160 deg. Differential neutron cross sections for the excitation of observed states in bismuth at 895 +- 12, 1606 +- 14, 2590 +- 15, 2762 +- 29, 3022 +- 21, and 3144 +- 15 keV are determined at incident neutron energies up to 4.0 MeV. An optical-statistical model is deduced from the measured values. This model, the present experimental results, and information available elsewhere in the literature are used to construct a comprehensive evaluated nuclear data file for elemental bismuth in the ENDF format. The evaluated file is particularly suited to the neutronic needs of the fusion-fission hybrid designer. 87 references, 10 figures, 6 tables

CINCH (confocal incoherent correlation holography) super resolution fluorescence microscopy based upon FINCH (Fresnel incoherent correlation holography).

Science.gov (United States)

Siegel, Nisan; Storrie, Brian; Bruce, Marc; Brooker, Gary

2015-02-07

FINCH holographic fluorescence microscopy creates high resolution super-resolved images with enhanced depth of focus. The simple addition of a real-time Nipkow disk confocal image scanner in a conjugate plane of this incoherent holographic system is shown to reduce the depth of focus, and the combination of both techniques provides a simple way to enhance the axial resolution of FINCH in a combined method called "CINCH". An important feature of the combined system allows for the simultaneous real-time image capture of widefield and holographic images or confocal and confocal holographic images for ready comparison of each method on the exact same field of view. Additional GPU based complex deconvolution processing of the images further enhances resolution.

Neutron spectra of /sup 239/Pu-Be neutron sources

Energy Technology Data Exchange (ETDEWEB)

Kumar, A; Nagarajan, P S [Bhabha Atomic Research Centre, Bombay (India). Div. of Radiation Protection

1977-01-01

Neutron spectra of /sup 239/Pu-Be(..cap alpha..,n) sources have been calculated by using the most recent data on the differential cross sections and angular distributions. The contribution from the multibody break-up reaction /sup 9/Be(..cap alpha..,..cap alpha..n)/sup 8/Be has also been incorporated. Modifications to the primary spectrum due to the secondary interactions in the source such as elastic scattering with beryllium, oxygen and plutonium and the /sup 9/Be(n,2n) and /sup 239/Pu(n,f) reaction have been calculated for different strengths and geometries. The present calculation has shown that the spectrum changes considerably because of these events within the source by way of smearing of peaks and filling up of valleys and raising the low energy part of the spectrum. Increase in H/D value leads to channeling of extra neutrons into the equatorial plane at the cost of the neutrons along the axial direction. The present calculations show that inclusion of secondary interactions to the extent considered in this work does not account completely for the increased intensity in the lower energy end of the measured spectrum.

Quantum States of Neutron in Earth's Gravitational Field

Indian Academy of Sciences (India)

Keywords. Neutron; gravitational field; Bohr-Sommerfeld-Wilson quantization; projectile motion; elastic collision; Olympiad. Author Affiliations. Vijay A Singh1 Praveen Pathak1 K Krishna Chaitanya2. Homi Bhabha Centre For Science Education (TIFR), V N Purav Marg, Mankhurd Mumbai 400088, India. Physics Department ...

Neutron diffraction and lattice defects

International Nuclear Information System (INIS)

Hamaguchi, Yoshikazu

1974-01-01

Study on lattice defects by neutron diffraction technique is described. Wave length of neutron wave is longer than that of X-ray, and absorption cross-section is small. Number of defects observed by ESR is up to several defects, and the number studied with electron microscopes is more than 100. Information obtained by neutron diffraction concerns the number of defects between these two ranges. For practical analysis, several probable models are selected from the data of ESR or electron microscopes, and most probable one is determined by calculation. Then, defect concentration is obtained from scattering cross section. It is possible to measure elastic scattering exclusively by neutron diffraction. Minimum detectable concentration estimated is about 0.5% and 10 20 - 10 21 defects per unit volume. A chopper and a time of flight system are used as a measuring system. Cold neutrons are obtained from the neutron sources inserted into reactors. Examples of measurements by using similar equipments to PTNS-I system of Japan Atomic Energy Research Institute are presented. Interstitial concentration in the graphite irradiated by fast neutrons is shown. Defects in irradiated MgO were also investigated by measuring scattering cross section. Study of defects in Ge was made by measuring total cross section, and model analysis was performed in comparison with various models. (Kato, T.)

Controlling the light propagation in one-dimensional photonic crystal via incoherent pump and interdot tunneling

Science.gov (United States)

Abbasabadi, Majid; Sahrai, Mostafa

2018-01-01

We investigated the propagation of an electromagnetic pulse through a one-dimensional photonic crystal doped with quantum-dot (QD) molecules in a defect layer. The QD molecules behave as a three-level quantum system and are driven by a coherent probe laser field and an incoherent pump field. No coherent coupling laser fields were introduced, and the coherence was created by the interdot tunnel effect. Further studied was the effect of tunneling and incoherent pumping on the group velocity of the transmitted and reflected probe pulse.

Proton and neutron densities from elastic electron scattering

International Nuclear Information System (INIS)

Frois, B.

1979-01-01

Elastic electron scattering has now determined extremely fine details of the shape of the nuclear groound state. The combination of (e,e) and muonic X-rays data are giving informations that are among the most precise on nuclear structure. This enables to see all the limitations of existing theories. However, we begin to have a very coherent description of nuclei with the self consistent field theories to a few percent. A very significant progress has been achieved with the calculations of RPA correlations in the round state in a self consistent way. Only recent experiments (on medium and heavy nuclei) of some significance for the understanding of the structure of the nucleus are reviewed

Energy-averaged neutron cross sections of fast-reactor structural materials

International Nuclear Information System (INIS)

Smith, A.; McKnight, R.; Smith, D.

1978-02-01

The status of energy-averaged cross sections of fast-reactor structural materials is outlined with emphasis on U.S. data programs in the neutron-energy range 1-10 MeV. Areas of outstanding accomplishment and significant uncertainty are noted with recommendations for future efforts. Attention is primarily given to the main constituents of stainless steel (e.g., Fe, Ni, and Cr) and, secondarily, to alternate structural materials (e.g., V, Ti, Nb, Mo, Zr). Generally, the mass regions of interest are A approximately 50 to 60 and A approximately 90 to 100. Neutron total and elastic-scattering cross sections are discussed with the implication on the non-elastic-cross sections. Cross sections governing discrete-inelastic-neutron-energy transfers are examined in detail. Cross sections for the reactions (n;p), (n;n',p), (n;α), (n;n',α) and (n;2n') are reviewed in the context of fast-reactor performance and/or diagnostics. The primary orientation of the discussion is experimental with some additional attention to the applications of theory, the problems of evaluation and the data sensitivity of representative fast-reactor systems

Two-photon exchange in elastic electron-nucleon scattering

International Nuclear Information System (INIS)

Blunden, P.G.; Melnitchouk, W.; Tjon, J.A.

2005-01-01

A detailed study of two-photon exchange in unpolarized and polarized elastic electron-nucleon scattering is presented, taking particular account of nucleon finite size effects. Contributions from nucleon elastic intermediate states are found to have a strong angular dependence, which leads to a partial resolution of the discrepancy between the Rosenbluth and polarization transfer measurements of the proton electric to magnetic form factor ratio, G E /G M . The two-photon exchange contribution to the longitudinal polarization transfer P L is small, whereas the contribution to the transverse polarization transfer P T is enhanced at backward angles by several percent, increasing with Q 2 . This gives rise to a small, E /G M obtained from the polarization transfer ratio P T /P L at large Q 2 . We also compare the two-photon exchange effects with data on the ratio of e + p to e - p cross sections, which is predicted to be enhanced at backward angles. Finally, we evaluate the corrections to the form factors of the neutron and estimate the elastic intermediate state contribution to the 3 He form factors

Neutron-based techniques for detection of explosives and drugs

Energy Technology Data Exchange (ETDEWEB)

Kiraly, B.; Olah, L.; Csikai, J. E-mail: csikai@falcon.phys.klte.hu

2001-06-01

Systematic measurements were carried out on the possible use of elastically backscattered Pu-Be neutrons combined with the thermal neutron reflection method for the identification of land mines and illicit drugs via he detection of H, C, N, and O elements as their major constituents. While ur present results show that these methods are capable of indicating the anomalies in bulky materials and observation of the major elements, e termination of the exact atom fractions needs further investigation.

Neutron-based techniques for detection of explosives and drugs

CERN Document Server

Kiraly, B; Csikai, J

2001-01-01

Systematic measurements were carried out on the possible use of elastically backscattered Pu-Be neutrons combined with the thermal neutron reflection method for the identification of land mines and illicit drugs via he detection of H, C, N, and O elements as their major constituents. While ur present results show that these methods are capable of indicating the anomalies in bulky materials and observation of the major elements, e termination of the exact atom fractions needs further investigation.

Microscopic theory of coherent and incoherent optical properties of semiconductor heterostructures

Energy Technology Data Exchange (ETDEWEB)

Schaefer, Martin

2008-09-02

An important question is whether there is a regime in which lasing from indirect semiconductors is possible. Thus, we discuss this question in this thesis. It is shown that under incoherent emission conditions it is possible to create an exciton condensate in multiple-quantum-well (MQW) systems. The influence of a MQW structure on the exciton lifetime is investigated. For the description of the light-matter interaction of a QW in the coherent excitation regime, the semiconductor Bloch equation (SBE) are used. The incoherent regime is described by the semiconductor luminescence equations (SLE). In principle it is even possible to couple SBE and SLE. The resulting theory is able to describe interactions between coherent and incoherent processes we investigate both, the coherent and the incoherent light-emission regime. Thus we define the investigated system and introduce the many-body Hamiltonian that describes consistently the light-matter interaction in the classical and the quantum limit. We introduce the SBE that allow to compute the light-matter interaction in the coherent scenario. The extended scattering model is used to investigate the absorption of a Ge QW for different time delays after the excitations. In this context, we analyze whether there is a regime in which optical gain can be realized. Then we apply a transfer-matrix method to include into our calculations the influence of the dielectric environment on the optical response. Thereafter the SLE for a MQW system are introduced. We derive a scheme that allows for decoupling environmental effects from the pure PL-emission properties of the QW. The PL of the actual QW system is obtained by multiplying this filter function and the free-space PL that describes the quantum emission into a medium with spatially constant background-refractive index. It is studied how the MQW-Bragg structure influences the PL-emission properties compared to the emission of a single QW device. As a last feature, it is shown

Plasma wakefields driven by an incoherent combination of laser pulses: a path towards high-average power laser-plasma accelerators

Energy Technology Data Exchange (ETDEWEB)

Benedetti, C.; Schroeder, C.B.; Esarey, E.; Leemans, W.P.

2014-05-01

he wakefield generated in a plasma by incoherently combining a large number of low energy laser pulses (i.e.,without constraining the pulse phases) is studied analytically and by means of fully-self-consistent particle-in-cell simulations. The structure of the wakefield has been characterized and its amplitude compared with the amplitude of the wake generated by a single (coherent) laser pulse. We show that, in spite of the incoherent nature of the wakefield within the volume occupied by the laser pulses, behind this region the structure of the wakefield can be regular with an amplitude comparable or equal to that obtained from a single pulse with the same energy. Wake generation requires that the incoherent structure in the laser energy density produced by the combined pulses exists on a time scale short compared to the plasma period. Incoherent combination of multiple laser pulses may enable a technologically simpler path to high-repetition rate, high-average power laser-plasma accelerators and associated applications.

The use of vanadium as a scattering standard for pulsed source neutron spectrometers

International Nuclear Information System (INIS)

Mayers, J.

1983-06-01

The Gaussian approximation for multiphonon cross-sections has been used in a calculation of the variation of vanadium cross-sections with incident neutron energy. The results show that vanadium behaves as an elastic scatterer to within a few percent on pulsed neutron spectrometers with incident neutron energies up to 1 eV. There is a calculated anisotropy in the scattering of 8%. It is found that the scattering properties of vanadium at 77K and 293K differ by a maximum of 1% except for neutron energies < 15 meV. (author)

Intravoxel Incoherent Motion MR Imaging in the Differentiation of Benign and Malignant Sinonasal Lesions: Comparison with Conventional Diffusion-Weighted MR Imaging.

Science.gov (United States)

Xiao, Z; Tang, Z; Qiang, J; Wang, S; Qian, W; Zhong, Y; Wang, R; Wang, J; Wu, L; Tang, W; Zhang, Z

2018-01-25

Intravoxel incoherent motion is a promising method for the differentiation of sinonasal lesions. This study aimed to evaluate the value of intravoxel incoherent motion in the differentiation of benign and malignant sinonasal lesions and to compare the diagnostic performance of intravoxel incoherent motion with that of conventional DWI. One hundred thirty-one patients with histologically proved solid sinonasal lesions (56 benign and 75 malignant) who underwent conventional DWI and intravoxel incoherent motion were recruited in this study. The diffusion coefficient ( D ), pseudodiffusion coefficient ( D *), and perfusion fraction ( f ) values derived from intravoxel incoherent motion and ADC values derived from conventional DWI were measured and compared between the 2 groups using the Student t test. Receiver operating characteristic curve analysis, logistic regression analysis, and 10-fold cross-validation were performed to evaluate the diagnostic performance of single-parametric and multiparametric models. The mean ADC and D values were significantly lower in malignant sinonasal lesions than in benign sinonasal lesions (both P benign and malignant sinonasal lesions. © 2018 by American Journal of Neuroradiology.

Coherent Forward Stimulated-Brillouin Scattering of a Spatially Incoherent Laser Beam in a Plasma and Its Effect on Beam Spray

International Nuclear Information System (INIS)

Grech, M.; Riazuelo, G.; Pesme, D.; Weber, S.; Tikhonchuk, V. T.

2009-01-01

A statistical model for forward stimulated-Brillouin scattering is developed for a spatially incoherent, monochromatic, laser beam propagating in a plasma. The threshold above which the laser beam spatial incoherence cannot prevent the coherent growth of forward stimulated-Brillouin scattering is computed. It is found to be well below the threshold for self-focusing. Three-dimensional simulations confirm its existence and reveal the onset of beam spray above it. From these results, we propose a new figure of merit for the control of propagation through a plasma of a spatially incoherent laser beam

Influence of concentration and temperature on tunneling and rotational dynamics of ammonium in Rb1-x (NH4)x I mixed crystals

International Nuclear Information System (INIS)

Natkaniec, I.; Dianoux, A.J.; Martinez-Sarrion, M.L.; Mestres, L.; Herraiz, M.; Smirnov, L.S.; Shuvalov, L.A.

2001-01-01

The Rb 1x (NH 4 ) x I mixed crystals are studied by inelastic incoherent neutron scattering using time-of-flight spectrometers in the concentration region of the x-T phase diagram 0.01≤x≤0.66 at 5≤T≤150K, where dynamic and static orientational disorder phases are generally found. It is shown that at 5 K rotational tunneling levels for ammonium concentrations x=0.01, 0.02 and 0.06 are similar. Additional tunneling levels are observed for x=0.16 which can be explained as the result of T-states splitting for account of NH 4 -NH 4 interaction. Tunneling levels are not observed for x=0.40 as the result of forming of orientational glass state. The elastic incoherent structure factors for concentrations 0.01≤x≤0.16 (dynamic orientational disordered α-phase), x=0.40 (orientational glass state) and 0.50≤x≤0.66 (orientational ordered state) have different temperature dependences

Continuum random-phase approximation study of the incoherent μ--e- conversion rate and its spurious 1- admixture

International Nuclear Information System (INIS)

Papakonstantinou, P.; Wambach, J.; Kosmas, T.S.; Faessler, A.

2006-01-01

The incoherent transition strength of the exotic μ - -e - conversion in the 208 Pb nucleus is investigated by utilizing the continuum random-phase-approximation method, appropriate for the evaluation of the rate that goes to the continuum of the nuclear spectrum. We find that the contribution of resonances lying high in the continuum is not negligible. Special attention is paid to the detailed study of the pronounced 1 - contribution that according to previous calculations, dominates the overall incoherent rate in about all the nuclear targets. The spurious center-of-mass admixture to the partial rate originating from the 1 - excitations is explored, and its elimination is performed by correcting properly the dipole operators. The results found this way show that the greatest portion of the total 1 - contribution to the incoherent rate is spurious

Compact extended model for doppler broadening of neutron absorption resonances in solids

International Nuclear Information System (INIS)

Villanueva, A. J; Granada, J.R

2009-01-01

We present a simplified compact model for calculating Doppler broadening of neutron absorption resonances in an incoherent Debye solid. Our model extends the effective temperature gas model to cover the whole range of energies and temperatures, and reduces the information of the dynamical system to a minimum content compatible with a much better accuracy of the calculation. This model is thus capable of replacing the existing algorithm in standard codes for resonance cross sections preparation aimed at neutron and reactor physics calculations. The model is applied to the 238 U 6.671 eV effective broadened cross section. We also show how this model can be used for thermometry in an improved fashion compared to the effective temperature gas model. Experimental data of the same resonance at low and high temperatures are also shown and the performances of each model are put to the test on this basis. [es

Multigroup P8 - elastic scattering matrices of main reactor elements

International Nuclear Information System (INIS)

Garg, S.B.; Shukla, V.K.

1979-01-01

To study the effect of anisotropic scattering phenomenon on shielding and neutronics of nuclear reactors multigroup P8-elastic scattering matrices have been generated for H, D, He, 6 Li, 7 Li, 10 B, C, N, O, Na, Cr, Fe, Ni, 233 U, 235 U, 238 U, 239 Pu, 240 Pu, 241 Pu and 242 Pu using their angular distribution, Legendre coefficient and elastic scattering cross-section data from the basic ENDF/B library. Two computer codes HSCAT and TRANS have been developed to complete this task for BESM-6 and CDC-3600 computers. These scattering matrices can be directly used as input to the transport theory codes ANISN and DOT. (auth.)

Microscopic cluster model analysis of 14O+p elastic scattering

International Nuclear Information System (INIS)

Baye, D.; Descouvemont, P.; Leo, F.

2005-01-01

The 14 O+p elastic scattering is discussed in detail in a fully microscopic cluster model. The 14 O cluster is described by a closed p shell for protons and a closed p3/2 subshell for neutrons in the translation-invariant harmonic-oscillator model. The exchange and spin-orbit parameters of the effective forces are tuned on the energy levels of the 15 C mirror system. With the generator-coordinate and microscopic R-matrix methods, phase shifts and cross sections are calculated for the 14 O+p elastic scattering. An excellent agreement is found with recent experimental data. A comparison is performed with phenomenological R-matrix fits. Resonances properties in 15 F are discussed

Neutron cross section covariances in the resonance region: 52Cr, 56Fe, 58Ni

Energy Technology Data Exchange (ETDEWEB)

Oblozinsky, P.; Cho, Y.-S.; Mattoon, C.M.; Mughabghab, S.F.

2010-08-03

We evaluated covariances for neutron capture and elastic scattering cross sections on major structural materials, {sup 52}Cr, {sup 56}Fe and {sup 58}Ni, in the resonance region which extends beyond 800 keV for each of them. Use was made of the recently developed covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. The data of most interest for AFCI applications, elastic scattering cross section uncertainties at energies above about few hundred keV, are on the level of about 12% for {sup 52}Cr, 7-8% for {sup 56}Fe and 5-6% for {sup 58}Ni.

Elastic softness of hybrid lead halide perovskites

KAUST Repository

Ferreira, A. C.

2018-01-26

Much recent attention has been devoted towards unravelling the microscopic optoelectronic properties of hybrid organic-inorganic perovskites (HOP). Here we investigate by coherent inelastic neutron scattering spectroscopy and Brillouin light scattering, low frequency acoustic phonons in four different hybrid perovskite single crystals: MAPbBr3, FAPbBr3, MAPbI3 and α-FAPbI3 (MA: methylammonium, FA: formamidinium). We report a complete set of elastic constants caracterized by a very soft shear modulus C44. Further, a tendency towards an incipient ferroelastic transition is observed in FAPbBr3. We observe a systematic lower sound group velocity in the technologically important iodide-based compounds compared to the bromide-based ones. The findings suggest that low thermal conductivity and hot phonon bottleneck phenomena are expected to be enhanced by low elastic stiffness, particularly in the case of the ultrasoft α-FAPbI3.

Proton-proton elastic scattering measurements at COSY

Energy Technology Data Exchange (ETDEWEB)

Bagdasarian, Zara [Forschungszentrum Juelich, Juelich (Germany); Tbilisi State University, Tbilisi (Georgia); Collaboration: ANKE-Collaboration

2014-07-01

To construct the reliable phase shift analysis (PSA) that can successfully describe the nucleon-nucleon (NN) interaction it is necessary to measure variety of experimental observables for both proton-proton (pp) and neutron-proton (np) elastic scattering. The polarized beams and targets at COSY-ANKE facility allow a substantial contribution to the existing database. The experiment was carried out in April 2013 at ANKE using a transversely polarized proton beam incident on an unpolarized hydrogen cluster target. Six beam energies of T{sub p}=0.8,1.6,1.8,2.0,2.2,2.4 GeV were used. The aim of this talk is to present the preliminary results for the analyzing power (A{sub y}) for the pp elastic scattering in the so-far unexplored 5 <θ{sub cm}<30 angular range. Our measurements are also compared to the world data and current partial wave solutions.

Elastic {pi}{sup +}p and {pi}{sup +}{pi}{sup +} scattering at LHC

Energy Technology Data Exchange (ETDEWEB)

Sobol, A.E.; Ryutin, R.A.; Petrov, V.A. [Institute for High Energy Physics, Protvino (Russian Federation); Murray, M.J. [University of Kansas, Lawrence (United States)

2010-10-15

We discuss the possibility of measuring leading neutron production at the LHC. These data could be used to extract from it {pi}{sup +}p and {pi}{sup +}{pi}{sup +} cross sections. In this note we give some estimates for the case of elastic cross sections and discuss related problems and prospects. (orig.)

Fission signal detection using helium-4 gas fast neutron scintillation detectors

Energy Technology Data Exchange (ETDEWEB)

Lewis, J. M., E-mail: lewisj@ufl.edu; Kelley, R. P.; Jordan, K. A. [Nuclear Engineering Program, University of Florida, Gainesville, Florida 32611 (United States); Murer, D. [Arktis Radiation Detectors Ltd., 8045 Zurich (Switzerland)

2014-07-07

We demonstrate the unambiguous detection of the fission neutron signal produced in natural uranium during active neutron interrogation using a deuterium-deuterium fusion neutron generator and a high pressure {sup 4}He gas fast neutron scintillation detector. The energy deposition by individual neutrons is quantified, and energy discrimination is used to differentiate the induced fission neutrons from the mono-energetic interrogation neutrons. The detector can discriminate between different incident neutron energies using pulse height discrimination of the slow scintillation component of the elastic scattering interaction between a neutron and the {sup 4}He atom. Energy histograms resulting from this data show the buildup of a detected fission neutron signal at higher energies. The detector is shown here to detect a unique fission neutron signal from a natural uranium sample during active interrogation with a (d, d) neutron generator. This signal path has a direct application to the detection of shielded nuclear material in cargo and air containers. It allows for continuous interrogation and detection while greatly minimizing the potential for false alarms.

Neutron scattering of a floating heavy water bridge

International Nuclear Information System (INIS)

Fuchs, Elmar C; Bitschnau, Brigitte; Woisetschlaeger, Jakob; Maier, Eugen; Beuneu, Brigitte; Teixeira, Jose

2009-01-01

When high voltage is applied to distilled water filled into two beakers close to each other, a water connection forms spontaneously, giving the impression of a floating water bridge (Fuchs et al 2007 J. Phys. D: Appl. Phys. 40 6112-4, 2008 J. Phys. D: Appl. Phys. 41 185502). This phenomenon is of special interest, since it comprises a number of phenomena currently tackled in modern water science. In this work, the first data on neutron scattering of a floating heavy water bridge are presented and possible interpretations are discussed. D 2 O was measured instead of H 2 O because of the very strong incoherent scattering of H. The obtained data support the 'bubble hypothesis' suggested earlier (Fuchs et al 2008).

Coherent and incoherent J /ψ photonuclear production in an energy-dependent hot-spot model

Science.gov (United States)

Cepila, J.; Contreras, J. G.; Krelina, M.

2018-02-01

In a previous publication, we have presented a model for the photoproduction of J /ψ vector mesons off protons, where the proton structure in the impact-parameter plane is described by an energy-dependent hot-spot profile. Here we extend this model to study the photonuclear production of J /ψ vector mesons in coherent and incoherent interactions of heavy nuclei. We study two methods to extend the model to the nuclear case: using the standard Glauber-Gribov formalism and using geometric scaling to obtain the nuclear saturation scale. We find that the incoherent cross section changes sizably with the inclusion of subnucleonic hot spots and that this change is energy dependent. We propose to search for this behavior by measuring the ratio of the incoherent to coherent cross sections at different energies. We compare the results of our model to results from the Relativistic Heavy-Ion Collider (RHIC) and from run 1 at the Large Hadron Collider (LHC), finding satisfactory agreement. We also present predictions for the LHC at the new energies reached in run 2. The predictions include J /ψ production in ultraperipheral collisions, as well as the recently observed photonuclear production in peripheral collisions.

Elasticity in Elastics-An in-vitro study.

Science.gov (United States)

Kamisetty, Supradeep Kumar; Nimagadda, Chakrapani; Begam, Madhoom Ponnachi; Nalamotu, Raghuveer; Srivastav, Trilok; Gs, Shwetha

2014-04-01

Orthodontic tooth movement results from application of forces to teeth. Elastics in orthodontics have been used both intra-orally and extra- orally to a great effect. Their use, combined with good patient co-operation provides the clinician with the ability to correct both anteroposterior and vertical discrepancies. Force decay over a period of time is a major problem in the clinical usage of latex elastics and synthetic elastomers. This loss of force makes it difficult for the clinician to determine the actual force transmitted to the dentition. It's the intent of the clinician to maintain optimal force values over desired period of time. The majority of the orthodontic elastics on the market are latex elastics. Since the early 1990s, synthetic products have been offered in the market for latex-sensitive patients and are sold as nonlatex elastics. There is limited information on the risk that latex elastics may pose to patients. Some have estimated that 0.12-6% of the general population and 6.2% of dental professionals have hypersensitivity to latex protein. There are some reported cases of adverse reactions to latex in the orthodontic population but these are very limited to date. Although the risk is not yet clear, it would still be inadvisable to prescribe latex elastics to a patient with a known latex allergy. To compare the in-vitro performance of latex and non latex elastics. Samples of 0.25 inch, latex and non latex elastics (light, medium, heavy elastics) were obtained from three manufacturers (Forestadent, GAC, Glenroe) and a sample size of ten elastics per group was tested. The properties tested included cross sectional area, internal diameter, initial force generated by the elastics, breaking force and the force relaxation for the different types of elastics. Force relaxation testing involved stretching the elastics to three times marketed internal diameter (19.05 mm) and measuring force level at intervals over a period of 48 hours. The data were

Evaluation of neutron nuclear data of natural calcium for CENDL-1

International Nuclear Information System (INIS)

Tang Gouyou; Bao Shanglian; Shi Zhaomin; Cao Wentian

1989-03-01

Neutron nuclear data of natural calcium for CENDL-1 has been evaluated in the energy region from 10 -5 ev to 20 MeV. Evaluated quantities are the total, non-elastic scattering, elastic and inelastic scattering, radiation capture, (n,p), (n,t), (n,2n), (n,a) reaction cross sections and the angular distributions of elastic and inelastic cross sections. Some of the data were calculated with the program AUJP based on the optical model and the program MUP2 based on the Hauser-Feshbach model and pre-equilibrium evaporation model. (author). 34 refs, 8 figs, 3 tabs

Neutron Diffusion in a Space Lattice of Fissionable and Absorbing Materials

Science.gov (United States)

Feynman, R. P.; Welton, T. A.

1946-08-27

Methods are developed for estimating the effect on a critical assembly of fabricating it as a lattice rather than in the more simply interpreted homogeneous manner. An idealized case is discussed supposing an infinite medium in which fission, elastic scattering and absorption can occur, neutrons of only one velocity present, and the neutron m.f.p. independent of position and equal to unity with the unit of length used.

Evaluation of neutron nuclear data for 12C

International Nuclear Information System (INIS)

Shibata, Keiichi

1983-12-01

Neutron nuclear data of 12 C have been evaluated for JENDL-3 in the energy range from 10 -5 eV to 20 MeV. Evaluated quantities are the total, elastic and inelastic scattering, radiative capture, photon-production, (n,p), (n,d) and (n,α) reaction cross sections and the angular or energy distribution of neutrons and photons. The total cross section below the threshold energy of the inelastic scattering has been calculated on the basis of the R-matrix theory. Three discrete levels have been taken into account for the inelastic scattering. (author)

Neutrons and antimony physical measurements and interpretations

International Nuclear Information System (INIS)

Smith, A. B.

2000-01-01

New experimental information for the elastic and inelastic scattering of ∼ 4--10 MeV neutrons from elemental antimony is presented. The differential measurements are made at ∼ 40 or more scattering angles and at incident neutron-energy intervals of ∼ 0.5 MeV. The present experimental results, those previously reported from this laboratory and as found in the literature are comprehensively interpreted using spherical optical-statistical and dispersive-optical models. Direct vibrational processes via core-excitation, isospin and shell effects are discussed. Antimony models for applications are proposed and compared with global, regional, and specific models reported in the literature

Curves and tables of neutron cross sections

International Nuclear Information System (INIS)

Nakagawa, Tsuneo; Asami, Tetsuo; Yoshida, Tadashi

1990-07-01

Neutron cross-section curves from the Japanese Evaluated Nuclear Data Library version 3, JENDL-3, are presented in both graphical and tabular form for users in a wide range of application areas in the nuclear energy field. The contents cover cross sections for all the main reactions induced by neutrons with an energy below 20 MeV including; total, elastic scattering, capture, and fission, (n,n'), (n,2n), (n,3n), (n,α), (n,p) reactions. The 2200 m/s cross-section values, resonance integrals, and Maxwellian- and fission-spectrum averaged cross sections are also tabulated. (author)

Quantum imaging with incoherently scattered light from a free-electron laser

Science.gov (United States)

Schneider, Raimund; Mehringer, Thomas; Mercurio, Giuseppe; Wenthaus, Lukas; Classen, Anton; Brenner, Günter; Gorobtsov, Oleg; Benz, Adrian; Bhatti, Daniel; Bocklage, Lars; Fischer, Birgit; Lazarev, Sergey; Obukhov, Yuri; Schlage, Kai; Skopintsev, Petr; Wagner, Jochen; Waldmann, Felix; Willing, Svenja; Zaluzhnyy, Ivan; Wurth, Wilfried; Vartanyants, Ivan A.; Röhlsberger, Ralf; von Zanthier, Joachim

2018-02-01

The advent of accelerator-driven free-electron lasers (FEL) has opened new avenues for high-resolution structure determination via diffraction methods that go far beyond conventional X-ray crystallography methods. These techniques rely on coherent scattering processes that require the maintenance of first-order coherence of the radiation field throughout the imaging procedure. Here we show that higher-order degrees of coherence, displayed in the intensity correlations of incoherently scattered X-rays from an FEL, can be used to image two-dimensional objects with a spatial resolution close to or even below the Abbe limit. This constitutes a new approach towards structure determination based on incoherent processes, including fluorescence emission or wavefront distortions, generally considered detrimental for imaging applications. Our method is an extension of the landmark intensity correlation measurements of Hanbury Brown and Twiss to higher than second order, paving the way towards determination of structure and dynamics of matter in regimes where coherent imaging methods have intrinsic limitations.

A new evaluation of neutron data for the 209Bi between 10-5 eV and 20 MeV

International Nuclear Information System (INIS)

Bersillon, O.; Caput, B.; Philis, C.A.

1982-09-01

A new evaluation of neutron induced cross-sections on 209 Bi has been completed within the full energy range 10 - 5 eV - 20 MeV and put under ENDF format. A careful study of the resonance region led to a consistent set of resonance parameters. On this basis, the tabulated cross-sections (total, elastic, capture) have been calculated using the Reich-Moore formalism. At higher energies a consistent set of optical model parameters has been obtained by fitting mainly the total cross-section between 0.7 and 150 MeV and elastic scattering angular distributions from 4 to 24 MeV. The so obtained neutron penetrabilities have been used for Hauser-Feshbach statistical model calculations which have been completed with pre-equilibrium and direct interaction components to get elastic and inelastic cross sections, angular distributions, secondary neutron spectra and gamma production. All the results are generally in good agreement with the available experimental data [fr

Neutron data evaluation for natural niobium

International Nuclear Information System (INIS)

Ma Gonggui; Zou Yiming; Wang Shiming

1992-01-01

The complete neutron nuclear data for natural niobium were evaluated based on both experimental data measured up to 1989 and calculated data with program MUP2 and AUJP. The present work was done for CENDL-2 and supersedes the CENDL-1 (MAT = 1411) evaluation. The following neutron data are given for Nb in the energy range 10 -5 eV to 20 MeV (MAT = 2411): total, elastic, nonelastic, total inelastic, inelastic cross sections to 13 discrete levels, inelastic continuum, (n,2n), (n,3n), (n,n'α) + (n,αn'), (n,n'p) + (n,pn'),(n,n'd) + (n,dn'), (n,p), (n,d), (n,t), (n,α) and capture cross sections. Derived data for MT = 251, 252 and 253 are also included. Angular distributions and energy spectra of secondary neutron are also given inelastic continuum,

Improved BER based on intensity noise alleviation using developed detection technique for incoherent SAC-OCDMA systems

Science.gov (United States)

Al-Khafaji, Hamza M. R.; Aljunid, S. A.; Fadhil, Hilal A.

2012-06-01

The major drawback of incoherent spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) systems is their inherent intensity noise originating due to the incoherency of the broadband light sources. In this paper, we propose a developed detection technique named the modified-AND subtraction detection for incoherent SAC-OCDMA systems. This detection technique is based upon decreasing the received signal strength during the decoding process by dividing the spectrum of the utilized code sequence. The proposed technique is capable of mitigating the intensity noise effect, as well as suppressing the multiple-access interference impact. Based on modified quadratic congruence (MQC) code, the analytical results reveal that the modified-AND detection offer best bit-error rate (BER) performance and enables MQC code to support higher transmission rate up to 1.25 Gb/s compared to conventional AND detection. Furthermore, we ascertained that the proposed technique enhances the system performance using a simulation experiment.

Thermodynamics and elastic properties of Ir from first-principle calculations

International Nuclear Information System (INIS)

Li Qiang; Huang Duohui; Cao Qilong; Wang Fanhou

2013-01-01

Within the framework of the quasiharmonic approximation, the thermodynamics and elastic properties, including phonon dispersion curves, equation of state, linear thermal expansion coefficient and temperature-dependent entropy, enthalpy, heat capacity, elastic constants, bulk modulus, shear modulus, Young's modulus of Ir have been studied using first-principles projector-augmented wave method. The results revealed that the predicted phonon dispersion curves of Ir are in agreement with the experimental measurements by neutron diffractions. Considering the thermal electronic contribution to Helmholtz free energy, the calculated entropy, enthalpy, heat capacity and linear thermal expansion co- efficient from the first-principle are consistent well with the experimental data. At 2600 K, the electronic heat capacity accounts for 17% of the total heat capacity at constant pressure, thus the thermal electronic contribution to Helmholtz free energy is very important. The predicted elastic constants, bulk modulus, shear modulus and Young's modulus at room temperature are also in agreement with the available measurements and increase with the increasing temperature. (authors)

Evidence of strong proton shape fluctuations from incoherent diffraction

International Nuclear Information System (INIS)

Mantysaari, H.; Schenke, B.

2016-01-01

We show within the saturation framework that measurements of exclusive vector meson production at high energy provide evidence for strong geometric fluctuations of the proton. In comparison, the effect of saturation scale and color charge fluctuations is weak. This knowledge will allow detailed future measurements of the incoherent cross section to tightly constrain the fluctuating geometry of the proton as a function of the parton momentum fraction x.

Detection and identification of explosives and illicit drugs using neutron based techniques

International Nuclear Information System (INIS)

Papp, A.; Csikai, J.; Debrecen University,

2011-01-01

Some methods developed in collaboration between the ATOMKI and IEP for bulk hydrogen analysis and for the detection and identification of illicit drugs are presented. Advantages and limitations of neutron techniques (reflection, transmission, elastic and inelastic scatterings, leakage spectra and angular yields of Be(d,n), Pu-Be, D-D, D-T and 252 Cf neutrons transmitted from thick samples, effects of hidden materials) are discussed. (author)

Compensation for incoherent ground motion

International Nuclear Information System (INIS)

Shigeru, Takeda; Hiroshi, Matsumoto; Masakazu, Yoshioka; Yasunori, Takeuchi; Kikuo, Kudo; Tsuneya, Tsubokawa; Mitsuaki, Nozaki; Kiyotomo, Kawagoe

1999-01-01

The power spectrum density and coherence function for ground motions are studied for the construction of the next generation electron-positron linear collider. It should provide a center of mass energy between 500 GeV-1 TeV with luminosity as high as 10 33 to 10 34 cm -2 sec -1 . Since the linear collider has a relatively slow repetition rate, large number of particles and small sizes of the beam should be generated and preserved in the machine to obtain the required high luminosity. One of the most critical parameters is the extremely small vertical beam size at the interaction point, thus a proper alignment system for the focusing and accelerating elements of the machine is necessary to achieve the luminosity. We describe recent observed incoherent ground motions and an alignment system to compensate the distortion by the ground motions. (authors)

Few-Nucleon Research at TUNL: Probing Two- and Three-Nucleon Interactions with Neutrons

Directory of Open Access Journals (Sweden)

Howell C.R.

2016-01-01

Full Text Available The central goal of few-nucleon research at the Triangle Universities Nuclear Laboratory (TUNL is to perform measurements that contribute to advancing ab-initio calculations of nuclear structure and reactions. The program aims include evaluating theoretical treatments of few-nucleon reaction dynamics through strategically comparing theory predictions to data, determining properties of the neutron-neutron interaction that are not accessible in two-nucleon reactions, and searching for evidence of longrange features of three-nucleon interactions, e.g., spin and isospin dependence. This paper will review studies of three- and four-nucleon systems at TUNL conducted using unpolarized and polarized neutron beams. Measurements of neutron-induced reactions performed by groups at TUNL over the last six years are described in comparison with theory predictions. The results are discussed in the context of the program goals stated above. Measurements of vector analyzing powers for elastic scattering in A=3 and A=4 systems, differential cross sections for neutron-deuteron elastic scattering and neutrondeuteron breakup in several final-state configurations are described. The findings from these studies and plans for the coming three years are presented in the context of worldwide activities in this front, in particular, research presented in this session.

Neutron scattering and models: Silver

International Nuclear Information System (INIS)

Smith, A.B.

1996-07-01

Differential neutron elastic-scattering cross sections of elemental silver were measured from 1.5 → 10 MeV at ∼ 100 keV intervals up to 3 MeV, at ∼ 200 keV intervals from 3 → 4 MeV, and at ∼ 500 keV intervals above 4 MeV. At ≤ 4 MeV the angular range of the measurements was ∼ 20 0 → 160 0 with 10 measured values below 3 MeV and 20 from 3 → 4 MeV at each incident energy. Above 4 MeV ≥ 40 scattering angles were used distributed between ∼ 17 0 and 16 0 All of the measured elastic distributions included some contributions due to inelastic scattering. Below 4 MeV the measurements determined cross sections for ten inelastically-scattered neutron groups corresponding to observed excitations of 328 ± 13, 419 ± 50, 748 ± 25, 908 ± 26, 115 ± 38, 1286 ± 25, 1507 ± 20, 1632 ± 30, 1835 ± 20 and 1944 ± 26 keV. All of these inelastic groups probably were composites of contributions from the two isotopes 107 Ag and 109 Ag. The experimental results were interpreted in terms of the spherical optical model and of rotational and vibrational coupled-channels models, and physical implications are discussed. In particular, the neutron-scattering results are consistent with a ground-state rotational band with a quadrupole deformation Β 2 = 0.20 ± ∼ 10% for both of the naturally-occurring silver isotopes

Incoherent scattering of gamma photons for non-destructive tomographic inspection of pipeline

International Nuclear Information System (INIS)

Sharma, Amandeep; Sandhu, B.S.; Singh, Bhajan

2010-01-01

A scanner system, operating in a non-destructive and non-invasive way, is presented for pipeline to determine its location in land soil, wall thickness, type of liquid flowing and crack/blockage position. The present experiment simulates a real case where pipe corrosion (wall thinning) under insulation can be known from the study of incoherent scattering of 662 keV gamma photons. The incoherent scattered intensity, obtained by unfolding (deconvolution) the experimental pulse-height distribution of NaI(Tl) scintillation detector with the help of inverse response matrix, provides the desired information. The method is quite sensitive for small change (∼1 mm) in the thickness of pipe wall, locating a defect of 1 mm width under insulation and a small change (∼0.1 gm cm -3 ) in the density of liquid flowing through pipe.

Sensitivity of neutron scattering properties to the coupling to giant resonances

International Nuclear Information System (INIS)

Delaroche, J.P.; Guss, P.P.; Floyd, C.E.; Walter, R.L.; Tornow, W.

1983-01-01

Extended coupled channels calculations have been performed for neutron elastic and inelastic cross sections and analyzing powers for vibrational nuclei with 40 208 Pb and 12 MeV results for 40 Ca are illustrated here

The structure of liquid water by polarized neutron diffraction and reverse Monte Carlo modelling.

Science.gov (United States)

Temleitner, László; Pusztai, László; Schweika, Werner

2007-08-22

The coherent static structure factor of water has been investigated by polarized neutron diffraction. Polarization analysis allows us to separate the huge incoherent scattering background from hydrogen and to obtain high quality data of the coherent scattering from four different mixtures of liquid H(2)O and D(2)O. The information obtained by the variation of the scattering contrast confines the configurational space of water and is used by the reverse Monte Carlo technique to model the total structure factors. Structural characteristics have been calculated directly from the resulting sets of particle coordinates. Consistency with existing partial pair correlation functions, derived without the application of polarized neutrons, was checked by incorporating them into our reverse Monte Carlo calculations. We also performed Monte Carlo simulations of a hard sphere system, which provides an accurate estimate of the information content of the measured data. It is shown that the present combination of polarized neutron scattering and reverse Monte Carlo structural modelling is a promising approach towards a detailed understanding of the microscopic structure of water.

Benchmarking a first-principles thermal neutron scattering law for water ice with a diffusion experiment

Directory of Open Access Journals (Sweden)

Holmes Jesse

2017-01-01

Full Text Available The neutron scattering properties of water ice are of interest to the nuclear criticality safety community for the transport and storage of nuclear materials in cold environments. The common hexagonal phase ice Ih has locally ordered, but globally disordered, H2O molecular orientations. A 96-molecule supercell is modeled using the VASP ab initio density functional theory code and PHONON lattice dynamics code to calculate the phonon vibrational spectra of H and O in ice Ih. These spectra are supplied to the LEAPR module of the NJOY2012 nuclear data processing code to generate thermal neutron scattering laws for H and O in ice Ih in the incoherent approximation. The predicted vibrational spectra are optimized to be representative of the globally averaged ice Ih structure by comparing theoretically calculated and experimentally measured total cross sections and inelastic neutron scattering spectra. The resulting scattering kernel is then supplied to the MC21 Monte Carlo transport code to calculate time eigenvalues for the fundamental mode decay in ice cylinders at various temperatures. Results are compared to experimental flux decay measurements for a pulsed-neutron die-away diffusion benchmark.

An experimental test of charge symmetry in n-p elastic scattering

International Nuclear Information System (INIS)

Birchall, J.; Davison, N.E.; Gubler, H.P.

1982-06-01

An experiment is described to investigate the isospin-mixing, charge-symmetry breaking component in the n-p interaction. The experiment measures the difference ΔA between the neutron and proton analyzing power Asub(n) and Asub(p) in n-p elastic scattering at 500 MeV. The experiment consists of two interleaved phases in which polarised neutrons, respectively unpolarised neutrons are scattered from an unpolarised, respectively polarised proton target of the frozen spin type. Designed as a null-measurement requiring no accurately known polarisation standards, the experiment determines the difference in angle at which Asub(n) and Asub(p) cross through zero. It is intended to provide an unambiguous test of a class IV charge-symmetry breaking effect to the level of ΔA approximately equal to 0.001, corresponding to a laboratory angle difference at zero crossing of approximately 0.05 0

Neutron scattering. Lectures of the JCNS laboratory course held at Forschungszentrum Juelich and the research reactor FRM II of TU Munich

International Nuclear Information System (INIS)

Brueckel, T.; Heger, G.; Richter, D.; Zorn, R.

2007-01-01

The following topics are dealt with: Fourier transform, basic assumptions of quantum mechanics and the Born approximation, symmtery in crystals, neutron sources, neutron elastic scattering and properties, polarized neutron scattering, correlation functions measured by scattering experiments, grazing incidence neutron scattering, neutron diffractometers, small-angle scattewring inelastic crystal spectrometers, time-of-flight spectrometers using NSE, structure determination, inelastic neutron scattering with phonon and magnon excitations, structure of complex fluids and macromolecules, polymer dynamics, magnetism. (HSI)

Anisotropic kernel p(μ → μ') for transport calculations of elastically scattered neutrons

International Nuclear Information System (INIS)

Stevenson, B.

1985-01-01

Literature in the area of anisotropic neutron scattering is by no means lacking. Attention, however, is usually devoted to solution of some particular neutron transport problem and the model employed is at best approximate. The present approach to the problem in general is classically exact and may be of some particular value to individuals seeking exact numerical results in transport calculations. For attempts neutrons originally directed toward the unit vector Omega, it attempts the evaluation of p(theta'), defined such that p(theta') d theta' is that fraction of scattered neutrons that emerges in the vicinity of a cone i.e., having been scattered to between angles theta' and theta' + d theta' with the axis of preferred orientation i; Omega makes an angle theta with i. The relative simplicity of the final form of the solution for hydrogen, in spite of the complicated nature of the limits involved, is a trade-off that truly is not necessary. The exact general solution presented here in integral form, has exceedingly simple limits, i.e., 0 ≤ theta' ≤ π regardless of the material involved; but the form of the final solution is extraordinarily complicated

A system for fast neutron radiography

International Nuclear Information System (INIS)

Klann, R.T.

1997-01-01

A system has been designed and a neutron generator installed to perform fast neutron radiography. With this system, objects as small as a coin and as large as a 19 liter container have been radiographed. The neutron source is an MF Physics A-711 neutron generator which produces 3 x 10[sup 10] neutrons/second with an average energy of 14. 5 MeV. The radiography system uses x-ray scintillation screens and film in commercially available light-tight cassettes. The cassettes have been modified to include a thin sheet of plastic to produce protons from the neutron beam through elastic scattering from hydrogen and other low Z materials in the plastic. For film densities from 1.8 to 3.0, exposures range from 1.9 x 10[sup 7] n/cm[sup 2] to 3.8 x 10[sup 8] n/cm[sup 2] depending on the type of screen and film. The optimum source-to-film distance was found to be 150 cm. At this distance, the geometric unsharpness was determined to be approximately 2.2-2.3 mm and the smallest hole that could be resolved in a 1.25 cm thick sample had a diameter of 0.079 cm

Quasi-elastic cross sections for 1GeV proton incident on {sup 4}He and {sup 12}C

Energy Technology Data Exchange (ETDEWEB)

Nishimura, M.; Nakamoto, T.; Shigyo, N. [Kyushu Univ., Fukuoka (Japan). Faculty of Engineering] [and others

1997-03-01

The experiment of p-n quasi-elastic scattering cross sections was carried out for 1GeV protons on {sup 4}He and {sup 12}C. The coincident measurement was made at c.m. angles of {+-} 90deg. The experiment was simulated by the use of HETC (High Energy Transport Code). It was examined to apply the p-n quasi-elastic scattering cross sections to neutron flux measurement. (author)

Effect of neutron irradiation on vitreous carbon

International Nuclear Information System (INIS)

Kurolenkin, E.I.; Virgil'ev, Yu.S.; Chugunova, T.K.

1989-01-01

The change in mass (m), volume (V), specific electric resistance (ρ), coefficient of linear thermal expansion (α), dynamic elasticity modulus (E), and limit of bending strength (σ) of vitreous carbon are studied upon neutron irradiation. Samples for study were two forms of vitreous carbon obtained by hardening thermally reactive polymers at 900-1,000 degree K. Phenol-formaldehyde (bakelite lacquer A, Bakelite A) and furfural-phenol-formaldehyde (FM-2) resin were used. They were irradiated in the experimental water - water VVR-M reactor between 360-1,030 degree K. The maximal neutron flux was 1.65·10 21 neut/cm 2 . Neutron irradiation of vitreous carbon led to its shrinkage and accompanied weakening. Shrinkage and weakening of vitreous carbon was decreased with an increase of treatment and irradiation temperatures

Fast neutron scattering near shell closures: Scandium

International Nuclear Information System (INIS)

Smith, A.B.; Guenther, P.T.

1992-08-01

Neutron differential elastic- and inelastic-scattering cross sections are measured from ∼ 1.5 to 10 MeV with sufficient detail to define the energy-averaged behavior of the scattering processes. Neutrons corresponding to excitations of 465 ± 23, 737 ± 20, 1017 ± 34, 1251 ± 20, 1432 ± 23 and 1692 ± 25 keV are observed. It is shown that the observables, including the absorption cross section, are reasonably described with a conventional optical-statistical model having energy-dependent geometric parameters. These energy dependencies are alleviated when the model is extended to include the contributions of the dispersion relationship. The model parameters are conventional, with no indication of anomalous behavior of the neutron interaction with 45 Sc, five nucleons from the doubly closed shell at 40 Ca

Characterization of Crystallographic Structures Using Bragg-Edge Neutron Imaging at the Spallation Neutron Source

Directory of Open Access Journals (Sweden)

Gian Song

2017-12-01

Full Text Available Over the past decade, wavelength-dependent neutron radiography, also known as Bragg-edge imaging, has been employed as a non-destructive bulk characterization method due to its sensitivity to coherent elastic neutron scattering that is associated with crystalline structures. Several analysis approaches have been developed to quantitatively determine crystalline orientation, lattice strain, and phase distribution. In this study, we report a systematic investigation of the crystal structures of metallic materials (such as selected textureless powder samples and additively manufactured (AM Inconel 718 samples, using Bragg-edge imaging at the Oak Ridge National Laboratory (ORNL Spallation Neutron Source (SNS. Firstly, we have implemented a phenomenological Gaussian-based fitting in a Python-based computer called iBeatles. Secondly, we have developed a model-based approach to analyze Bragg-edge transmission spectra, which allows quantitative determination of the crystallographic attributes. Moreover, neutron diffraction measurements were carried out to validate the Bragg-edge analytical methods. These results demonstrate that the microstructural complexity (in this case, texture plays a key role in determining the crystallographic parameters (lattice constant or interplanar spacing, which implies that the Bragg-edge image analysis methods must be carefully selected based on the material structures.

Thermomechanical theory of materials undergoing large elastic and viscoplastic deformation (AWBA development program)

International Nuclear Information System (INIS)

Martin, S.E.; Newman, J.B.

1980-11-01

A thermomechanical theory of large deformation elastic-inelastic material behavior is developed which is based on a multiplicative decomposition of the strain. Very general assumptions are made for the elastic and inelastic constitutive relations and effects such as thermally-activated creep, fast-neutron-flux-induced creep and growth, annealing, and strain recovery are compatible with the theory. Reduced forms of the constitutive equations are derived by use of the second law of thermodynamics in the form of the Clausius-Duhem inequality. Observer invariant equations are derived by use of an invariance principle which is a generalization of the principle of material frame indifference

Neutron Skin Thickness of 48Ca from a Nonlocal Dispersive Optical-Model Analysis

Science.gov (United States)

Mahzoon, M. H.; Atkinson, M. C.; Charity, R. J.; Dickhoff, W. H.

2017-12-01

A nonlocal dispersive optical-model analysis has been carried out for neutrons and protons in 48Ca. Elastic-scattering angular distributions, total and reaction cross sections, single-particle energies, the neutron and proton numbers, and the charge distribution have been fitted to extract the neutron and proton self-energies both above and below the Fermi energy. From the single-particle propagator resulting from these self-energies, we have determined the charge and neutron matter distributions in 48Ca. A best fit neutron skin of 0.249 ±0.023 fm is deduced, but values up to 0.33 fm are still consistent. The energy dependence of the total neutron cross sections is shown to have a strong sensitivity to the skin thickness.

Few-MeV neutrons incident on yttrium

International Nuclear Information System (INIS)

Budtz-Jorgensen, C.; Guenther, P.; Smith, A.; Whalen, J.

1982-09-01

Neutron total and scattering cross sections of elemental yttrium are measured in the few-MeV region with broad resolutions. The total-cross section measurements extend from approx. = 0.5 to 4.2 MeV in steps of less than or equal to 0.1 MeV. Neutron elastic- and inelastic-scattering cross sections are measured from approx. = 1.5 to 4.0 MeV, at incident-neutron energy intervals of less than or equal to 50 keV and at ten or more scattering angles distributed between 20 and 160 deg. Inelastically-scattered neutron groups are observed corresponding to the excitation of levels at 909 +- 23, 1504 +- 20, 1747 +- 16, 2224 +- 16, 2567 +- 26, 2889 +- 12 and 3104 +- 10 keV. The experimental results are discussed in terms of the spherical optical-statistical, coupled-channels and core-coupling models and compared with corresponding quantities given in the evaluated nuclear data file ENDF/B-V

Electron and ion temperatures: a comparison of ground-based incoherent scatter and AE-C satellite measurements

International Nuclear Information System (INIS)

Benson, R.F.; Bauer, P.; Brace, L.H.; Carlson, H.C.; Hagen, J.; Hanson, W.B.; Hoegy, W.R.; Torr, M.R.; Wickwar, V.B.

1977-01-01

The Atmosphere Exploere-C satellite (AE-C) is uniquely suited for correlative studies with ground-based stations because its on-board propulsion system enables a desired ground station overflight condition to be maintained for a period of several weeks. It also provides the first low-altitude (below 260 km) comparison of satellite and incoherent scatter electron and ion temperatures. More than 40 comparisons of remote and in situ measurements were made by using data from AE-C and four incoherent scatter stations (Arecibo, Chatanika, Millstone Hill, and St. Santin). The results indicate very good agreement between satellite and ground measurements of the ion temperature, the average satellite retarding potential analyzer temperatures differing from the average incoherent scatter temperatures by -2% at St. Santin, +3% at Millstone Hill, and +2% at Arecibo. The electron temperatures also agree well, the average satellite temperatures exceeding the average incoherent scatter temperatures by 3% at St. Santin, 2% at Arecibo, and 11% at Millstone Hill. Several temperature comparisons were made between AE-C and Chatanika. In spite of the highly variable ionosphere often encountered at this high-latitude location, good agreement was obtained between the in situ and remote measurements of electron and ion temperatures. Longitudinal variations are found to be very important in the comparisons of electron temperature in some locations. The agreement between the electron temperatures is considerably better than that found in some earlier comparisons involving satellities at higher altitudes

Bulk media assay using backscattered Pu-Be neutrons

CERN Document Server

Csikai, J

1999-01-01

Spectral yields of elastically backscattered Pu-Be neutrons measured for graphite, water, polyethylene, liquid nitrogen, paraffin oil, SiO sub 2 , Al, Fe, and Pb slabs show a definite correlation with the energy dependence of the elastic scattering cross sections, sigma sub E sub L (E sub n). The C, N and O can be identified by the different structures in their sigma sub E sub L (E sub n) functions. The integrated spectral yields versus thickness exhibit saturation for each sample. The interrogated volume is limited by the presence of hydrogen in the sample. (author)

Experimental study of the fusion dynamics of 32,34S + 197Au with quasi-elastic scattering

International Nuclear Information System (INIS)

Schuck, T.J.; Dasgupta, M.; Timmers, H.

2000-01-01

Full text: The fusion dynamics of heavy systems, such as 64 Ni + 208 Pb, leading to the synthesis of super-heavy elements is presently not fully understood. Typical beam energies in such reactions are of the order or smaller than the Coulomb barrier height to minimize the excitation energy of the compound system and increase the survival probability of evaporation residues. It is known that at such energies the relative motion of projectile and target couples to internal degrees of freedom of the system, such as collective motion and particle transfer. This can give rise to a distribution of fusion barriers, which generally leads to an enhancement of the fusion cross-section below the Coulomb barrier. The important role of the individual degrees of freedom can be identified by extracting representations of the barrier distribution from fusion excitation functions. Complementary representations can be obtained from measurements of the quasi-elastic or elastic scattering excitation functions at backward angles. The sensitivity of the representations from scattering is limited to the lower energy part of the barrier distribution, which, however, may contain important signatures of positive Q-value neutron transfer channels. Neutron transfer may be a precursor of neutron flow and neck-formation, which are considered in macroscopic models of the fusion of heavy systems. In order to study the influence of neutron transfer in heavy fusion reactions, quasielastic scattering has been measured for 32 , 34 S + 197 Au at energies spanning the Coulomb barrier. The quasi-elastic yield, including inelastic and transfer reactions, was detected at 165 deg with a Si-surface barrier detector. The excitation functions have been normalized to Rutherford scattering, detected at 30 deg using an existing gas ionisation detector. Representations of the barrier distributions have been extracted and are compared with earlier measurements for 32 S + 208 Pb

Production of flat KrF laser focal profiles with echelon free-induced spatial incoherence

International Nuclear Information System (INIS)

Deniz, A.V.; Obenschain, S.P.; Pronko, M.; Lehmberg, R.H.

1990-01-01

High gain direct-drive laser fusion requires a uniform spherical pellet implosion. This in turn requires that the focal profile of each driving beam be sufficiently uniform and controlled. Several methods for producing uniform beams have been proposed. One promising technique, echelon free-induced spatial incoherence (ISI), consists of propagating a broadband spatially incoherent beam through an entire laser system. This technique will be used in the Nike laser, which is a twenty-four- to forty-eight-beam multikilojoule KrF system currently under construction at the Naval Research Laboratory (NRL). This paper presents measurements of focal profiles of laser light smoothed by echelon free ISI from a KrF oscillator and amplifier. The initial implementation is shown

Measurement of differential incoherent scattering cross-sections of 145 keV photons from K-shell electrons

Energy Technology Data Exchange (ETDEWEB)

Acharya, V B; Ghumman, B S [Punjabi Univ., Patiala (India). Dept. of Physics

1980-06-01

Differential cross-sections for incoherent scattering of 145 keV photons from K-shell electrons of tin, silver and molybdenum have been measured at 110deg to investigate the effect of electron binding on differential cross-sections in the low energy region. The incoherent scattered photons are selected in coincidence with X-rays which follow the vacancies caused by the ejection of the electrons. NaI(Tl) scintillators are used for the detection of scattered photons and emitted X-rays. The experimental results are compared with the available theoretical data.

Development of neutron shielding material using metathesis-polymer matrix

Energy Technology Data Exchange (ETDEWEB)

Sakurai, Yoshinori E-mail: ysakurai@rri.kyoto-u.ac.jp; Sasaki, Akira; Kobayashi, Tooru

2004-04-21

A neutron shielding material using a metathesis-polymer matrix, which is a thermosetting resin, was developed. This shielding material has characteristics that can be controlled for different mixing ratios of neutron absorbers and for formation in the laboratory. Additionally, the elastic modulus can be changed at the hardening process, from a flexible elastoma to a mechanically tough solid. Experiments were performed at the Kyoto University Research Reactor in order to determine the important characteristics of this metathesis-polymer shielding material, such as neutron shielding performance, secondary gamma-ray generation and activation. The metathesis-polymer shielding material was shown to be practical and as effective as the other available shielding materials, which mainly consist of thermoplastic resin.

In-situ measurement of texture and elastic strains with HIPPO-CRATES

International Nuclear Information System (INIS)

Hartig, Ch.; Vogel, S.C.; Mecking, H.

2006-01-01

In this paper, the micromechanical interaction between constituents of a metallic material during elastic and plastic deformation are analyzed by comparing experimental results with modeling predictions. This comparison aims at determining the locally acting internal stresses, the spatial distribution of strains and the rules allowing deriving the macroscopic behavior of the material from the behavior of its microscopic constituents. We report the application of a new deformation apparatus CRATES, which allows measuring texture and crystal lattice spacings, and from these crystal lattice strains, using neutron diffraction. From the in-situ measured elastic lattice strains ε hkl the corresponding local stresses can be derived. The deformation apparatus allows uni-axial tensile or compressive deformation up to 100 kN and is specifically designed for use in the HIPPO neutron time-of-flight diffractometer. In this paper, we report initial results on an iron-copper model system (Fe100, Fe33Cu67, Fe67Cu33, vol.%) and commercial magnesium alloys (Mg-AZ31 and Mg-AZ80). Finite element calculations using a crystal-plastic constitutive law, allowing for shear and hardening of crystallographic slip-systems, were used for the interpretation of the measurements

Temperature-dependent dynamical transitions of different classes of amino acid residue in a globular protein.

Science.gov (United States)

Miao, Yinglong; Yi, Zheng; Glass, Dennis C; Hong, Liang; Tyagi, Madhusudan; Baudry, Jerome; Jain, Nitin; Smith, Jeremy C

2012-12-05

The temperature dependences of the nanosecond dynamics of different chemical classes of amino acid residue have been analyzed by combining elastic incoherent neutron scattering experiments with molecular dynamics simulations on cytochrome P450cam. At T = 100-160 K, anharmonic motion in hydrophobic and aromatic residues is activated, whereas hydrophilic residue motions are suppressed because of hydrogen-bonding interactions. In contrast, at T = 180-220 K, water-activated jumps of hydrophilic side chains, which are strongly coupled to the relaxation rates of the hydrogen bonds they form with hydration water, become apparent. Thus, with increasing temperature, first the hydrophobic core awakens, followed by the hydrophilic surface.

Secondary relaxation in two engineering thermoplastics by neutron scattering and dielectric spectroscopy

CERN Document Server

Arrese, S; Alegria, A; Colmenero, J; Frick, B

2002-01-01

We present a preliminary investigation of the dynamics of glassy polycarbonate (PC) and polysulfone (PSF) by means of quasielastic neutron scattering and dielectric spectroscopy. Whereas the consideration of pure phenylene ring pi-flips is enough to explain the momentum-transfer (Q) dependence of the inelastic intensity measured for PSF, in the case of PC the Q dependence of both the coherent and the incoherent scattering functions reveal the existence in this polymer of some more complex motion of the phenylene ring. On the other hand, the similarity of the energy landscapes deduced from the different techniques points to a closely related molecular origin for all the relaxation/motions observed. (orig.)

Secondary relaxation in two engineering thermoplastics by neutron scattering and dielectric spectroscopy

International Nuclear Information System (INIS)

Arrese-Igor, S.; Arbe, A.; Alegria, A.; Colmenero, J.; Frick, B.

2002-01-01

We present a preliminary investigation of the dynamics of glassy polycarbonate (PC) and polysulfone (PSF) by means of quasielastic neutron scattering and dielectric spectroscopy. Whereas the consideration of pure phenylene ring π-flips is enough to explain the momentum-transfer (Q) dependence of the inelastic intensity measured for PSF, in the case of PC the Q dependence of both the coherent and the incoherent scattering functions reveal the existence in this polymer of some more complex motion of the phenylene ring. On the other hand, the similarity of the energy landscapes deduced from the different techniques points to a closely related molecular origin for all the relaxation/motions observed. (orig.)

Measurement of cross sections for the scattering of neutrons in the energy range from 2 MeV to 4 MeV with the 15N(p,n) reaction as neutron source

International Nuclear Information System (INIS)

Poenitz, Erik

2010-01-01

In future nuclear facilities, the materials lead and bismuth can play a more important role than in today's nuclear reactors. Reliable cross section data are required for the design of those facilities. In particular the neutron transport in the lead spallation target of an Accelerator-Driven Subcritical Reactor strongly depends on the inelastic neutron scattering cross sections in the energy region from 0.5 MeV to 6 MeV. In the recent 20 years, elastic and inelastic neutron scattering cross sections were measured with high precision for a variety of elements at the PTB time-of-flight spectrometer. The D(d,n) reaction was primarily used for the production of neutrons. Because of the Q value of the reaction and the available deuteron energies, neutrons in the energy range from 6 MeV to 16 MeV can be produced. For the cross section measurement at lower energies, however, another neutron producing reaction is required. The 15 N(p,n) 15 O reaction was chosen, as it allows the production of monoenergetic neutrons with up to 5.7MeV energy. In this work, the 15 N(p,n) reaction was studied with focus on the suitability as a source for monoenergetic neutrons in scattering experiments. This includes the measurement of differential cross sections for the neutron producing reaction and the choice of optimum target conditions. Differential elastic and inelastic neutron scattering cross sections were measured for lead at four energies in the region from 2 MeV to 4 MeV incident neutron energy using the time-of-flight technique. A lead sample with natural isotopic composition was used. NE213 liquid scintillation detectors with well-known detection efficiencies were used for the detection of the scattered neutrons. Angle-integrated cross sections were determined by a Legendre polynomial expansion using least-squares methods. Additionally, measurements were carried out for isotopically pure 209 Bi and 181 Ta samples at 4 MeV incident neutron energy. Results are compared with other

Neutron induced alpha production from carbon between 18 and 22 MeV

International Nuclear Information System (INIS)

Stevens, A.P.

1976-10-01

Cross sections for neutron induced alpha production in carbon were measured at seventeen energies between 18 and 22 MeV, using a deuterated anthracene crystal as both target and detector. Pulse shape discrimination was employed to separate the alphas and elastically scattered deuterons from the other reaction products. Published (n,d) elastic scattering data were used as a standard to obtain the alpha production cross sections. Comparison with available measurements shows good agreement

The SCANDAL facility - How to measure elastic neutron scattering in the 50-130 MeV range

International Nuclear Information System (INIS)

Klug, Joakim

2001-01-01

The interest in neutrons of energies above 20 MeV is growing rapidly, since new applications are being developed or have been identified. Transmutation of nuclear waste and cancer therapy with neutron beams are two research fields that would benefit from new neutron scattering data at these energies. A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has been developed and installed at the neutron beam facility of the The Svedberg Laboratory in Uppsala. It can be used to study the (n,n), (n,p) and (n,d) reactions. This thesis describes the layout of the setup, the experimental procedure, and data analysis principles. The performance of the spectrometer is illustrated with measurements of the (n,p) and (n,n) reactions on 1 H and 12 C. In addition, the neutron beam facility is described in some detail

Report on the meeting of the working groups on neutron scattering applied to studying condensed matter, and neutron scattering and complementary methods applied in chemistry and biology

International Nuclear Information System (INIS)

1985-06-01

The present volume consists of 55 lectures. The subjects are: 1) Elastic neutron diffraction, 2) Lattice dynamics, 3) Diffusion, 4) Polymers, 5) Biology, 6) Methods and tools, 7) Magnetism. For distinct papers see hints under relevant topics. (BHO)

Fast neutron measurements at the nELBE time-of-flight facility

Directory of Open Access Journals (Sweden)

Junghansa A. R.

2015-01-01

Full Text Available The compact neutron-time-of-flight facility nELBE at the superconducting electron accelerator ELBE of Helmholtz-Zentrum Dresden-Rossendorf has been rebuilt. A new enlarged experimental hall with a flight path of up to 10 m is available for neutron time-of-flight experiments in the fast energy range from about 50 keV to 10 MeV. nELBE is intended to deliver nuclear data of fast neutron nuclear interactions e.g. for the transmutation of nuclear waste and improvement of neutron physical simulations of innovative nuclear systems. The experimental programme consists of transmission measurements of neutron total cross sections, elastic and inelastic scattering cross section measurements, and neutron induced fission cross sections. The inelastic scattering to the first few excited states in 56Fe was investigated by measuring the gamma production cross section with an HPGe detector. The neutron induced fission of 242Pu was studied using fast ionisation chambers with large homogeneous actinide deposits.

The integration of elastic wave properties and machine learning for the distribution of petrophysical properties in reservoir modeling

Science.gov (United States)

Ratnam, T. C.; Ghosh, D. P.; Negash, B. M.

2018-05-01

Conventional reservoir modeling employs variograms to predict the spatial distribution of petrophysical properties. This study aims to improve property distribution by incorporating elastic wave properties. In this study, elastic wave properties obtained from seismic inversion are used as input for an artificial neural network to predict neutron porosity in between well locations. The method employed in this study is supervised learning based on available well logs. This method converts every seismic trace into a pseudo-well log, hence reducing the uncertainty between well locations. By incorporating the seismic response, the reliance on geostatistical methods such as variograms for the distribution of petrophysical properties is reduced drastically. The results of the artificial neural network show good correlation with the neutron porosity log which gives confidence for spatial prediction in areas where well logs are not available.

Effect of different lay-ups on the microstructure, mechanical properties and neutron transmission of neutron shielding fibre metal laminates

International Nuclear Information System (INIS)

Fu, Xuelong; Tang, Xiaobin; Hu, Yubing; Li, Huaguan; Tao, Jie

2016-01-01

A novel neutron shielding fibre metal laminates (NSFMLs) with different lay-ups, composed of stacking layers of AA6061 plates, neutron shielding composite and carbon fibre reinforced polyimide (CFRP), were fabricated using hot molding process in atmospheric environments. The microstructure, mechanical properties and neutron transmission of the NSFMLs were evaluated, respectively. The results indicated that the NSFMLs possessed good mechanical properties owing to the good interfacial adhesion of the components. Tensile strength and elastic modulus of the NSFMLs increased with the numbers of lay-ups, while the elongation to fracture exhibited obvious declining tendency. Flexural strength and modulus of the NSFMLs were improved obviously with the increasing of stacking layers. Neutron transmission of the NSFMLs decreased obviously with increasing the number of lay-ups, owing to the increase of "1"0B areal density. Besides, the effect of carbon fibres on the neutron shielding performance of the NSFMLs was also taken into consideration. - Highlights: • A novel neutron shielding fibre metal laminates (NSFMLs) with different lay-ups was successfully fabricated using hot molding process. • Mechanical properties of the NSFMLs were performed in accordance with relative standards. • Neutron transmission of the NSFMLs was conducted according to the testing results. • The effect of carbon fibres on the neutron transmission of the NSFMLs was also investigated.

Effect of different lay-ups on the microstructure, mechanical properties and neutron transmission of neutron shielding fibre metal laminates

Energy Technology Data Exchange (ETDEWEB)

Fu, Xuelong [College of Material Science & Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 211100 (China); Department of Mechanical and Electronic Engineering, Jiangsu Polytechnic of Finance & Economics, Huai' an, 223003 (China); Tang, Xiaobin; Hu, Yubing; Li, Huaguan [College of Material Science & Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 211100 (China); Tao, Jie, E-mail: taojie@nuaa.edu.cn [College of Material Science & Technology, Nanjing University of Aeronautics & Astronautics, Nanjing, 211100 (China)

2016-07-15

A novel neutron shielding fibre metal laminates (NSFMLs) with different lay-ups, composed of stacking layers of AA6061 plates, neutron shielding composite and carbon fibre reinforced polyimide (CFRP), were fabricated using hot molding process in atmospheric environments. The microstructure, mechanical properties and neutron transmission of the NSFMLs were evaluated, respectively. The results indicated that the NSFMLs possessed good mechanical properties owing to the good interfacial adhesion of the components. Tensile strength and elastic modulus of the NSFMLs increased with the numbers of lay-ups, while the elongation to fracture exhibited obvious declining tendency. Flexural strength and modulus of the NSFMLs were improved obviously with the increasing of stacking layers. Neutron transmission of the NSFMLs decreased obviously with increasing the number of lay-ups, owing to the increase of {sup 10}B areal density. Besides, the effect of carbon fibres on the neutron shielding performance of the NSFMLs was also taken into consideration. - Highlights: • A novel neutron shielding fibre metal laminates (NSFMLs) with different lay-ups was successfully fabricated using hot molding process. • Mechanical properties of the NSFMLs were performed in accordance with relative standards. • Neutron transmission of the NSFMLs was conducted according to the testing results. • The effect of carbon fibres on the neutron transmission of the NSFMLs was also investigated.