WorldWideScience

Sample records for thermal neutron diffraction

  1. Thermal diffuse scattering in angular-dispersive neutron diffraction

    International Nuclear Information System (INIS)

    Popa, N.C.; Willis, B.T.M.

    1998-01-01

    The theoretical treatment of one-phonon thermal diffuse scattering (TDS) in single-crystal neutron diffraction at fixed incident wavelength is reanalysed in the light of the analysis given by Popa and Willis [Acta Cryst. (1994), (1997)] for the time-of-flight method. Isotropic propagation of sound with different velocities for the longitudinal and transverse modes is assumed. As in time-of-flight diffraction, there exists, for certain scanning variables, a forbidden range in the one-phonon TDS of slower-than-sound neutrons, and this permits the determination of the sound velocity in the crystal. A fast algorithm is given for the TDS correction of neutron diffraction data collected at a fixed wavelength: this algorithm is similar to that reported earlier for the time-of-flight case. (orig.)

  2. Thermal expansion study of simulated DUPIC fuel using neutron diffraction

    International Nuclear Information System (INIS)

    Kang, Kweon Ho; Ryu, H. J.; Bae, J. H.; Kim, H. S.; Song, K. C.; Yang, M. S.; Choi, Y. N.; Han, Y. S.; Oh, H. S.

    2001-07-01

    The lattice parameters of simulated DUPIC fuel and UO2 were measured from room temperature to 1273 K using neutron diffraction to investigate the thermal expansion and density variation with temperature. The lattice parameter of simulated DUPIC fuel is lower than that of UO2 and the linear thermal expansion of simulated DUPIC fuel is higher than that of UO2. For the temperature range from 298 to 1273 K, the average linear thermal expansion coefficients for UO2 and simulated DUPIC fuel are 10.471 ''10-6 and 10.751 ''10-6 K-1, respectively

  3. High pressure sample container for thermal neutron spectroscopy and diffraction on strongly scattering fluids

    International Nuclear Information System (INIS)

    Verkerk, P.; Pruisken, A.M.M.

    1979-01-01

    A description is presented of the construction and performance of a container for thermal neutron scattering on a fluid sample with about 1.5 cm -1 macroscopic cross section (neglecting absorption). The maximum pressure is about 900 bar. The container is made of 5052 aluminium capillary with inner diameter 0.75 mm and wall thickness 0.25 mm; it covers a neutron beam with a cross section of 9 X 2.5 cm 2 . The container has been successfully used in neutron diffraction and time-of-flight experiments on argon-36 at 120 K and several pressures up to 850 bar. It is shown that during these measurements the temperature gradient over the sample as well as the error in the absolute temperature were both less than 0.05 K. Subtraction of the Bragg peaks due to container scattering in diffraction experiments may be dfficult, but seems feasible because of the small amount of aluminium in the neutron beam. Correction for container scattering and multiple scattering in time-of-flight experiments may be difficult only in the case of coherently scattering samples and small scattering angles. (Auth.)

  4. Thermal diffuse scattering in time-of-flight neutron diffraction studied on SBN single crystals

    International Nuclear Information System (INIS)

    Prokert, F.; Savenko, B.N.; Balagurov, A.M.

    1994-01-01

    At time-of-flight (TOF) diffractometer D N-2, installed at the pulsed reactor IBR-2 in Dubna, Sr x Ba 1-x Nb 2 O 6 mixed single crystals (SBN-x) of different compositions (0.50 < x< 0.75) were investigated between 15 and 773 K. The diffraction patterns were found to be strongly influenced by the thermal diffuse scattering (TDS). The appearance of the TDS from the long wavelength acoustic models of vibration in single crystals is characterized by the ratio of the velocity of sound to the velocity of neutron. Due to the nature of the TOF Laue diffraction technique used on D N-2, the TDS around Bragg peaks has rather a complex profile. An understanding of the TDS close to Bragg peaks is essential in allowing the extraction of the diffuse scattering occurring at the diffuse ferroelectric phase transition in SBN crystals. 11 refs.; 9 figs.; 1 tab. (author)

  5. Neutron diffraction and thermal studies of amorphous CS2 realised by low-temperature vapour deposition

    International Nuclear Information System (INIS)

    Yamamuro, O.; Matsuo, T.; Onoda-Yamamuro, N.; Takeda, K.; Munemura, H.; Tanaka, S.; Misawa, M.

    2003-01-01

    We have succeeded in preparing amorphous carbon disulphide (CS 2 ) by depositing its vapour on a cold substrate at 10 K. Complete formation of the amorphous state has been confirmed by neutron diffraction and differential thermal analysis (DTA). The amorphous sample crystallized at ca. 70 K, which is lower than the hypothetical glass transition temperature (92 K) estimated from the DTA data of the (CS 2 ) x (S 2 Cl 2 ) 1-x binary mixture. CS 2 , a symmetric linear tri-atomic molecule, is the simplest of the amorphized molecular substances whose structural and thermal information has been reported so far. Comparison of the static structure factors S(Q) has shown that the orientational correlation of CS 2 molecules may be much stronger in the amorphous state than in the liquid state at higher temperature. (authors)

  6. Anisotropic thermal expansion of MgSiN2 from 10 to 300 K as measured by neutron diffraction

    NARCIS (Netherlands)

    Bruls, R.J.; Hintzen, H.T.J.M.; Metselaar, R.; Loong, C.K.

    2000-01-01

    The lattice parameters of orthorhombic MgSiN2 as a function of the temperature have been determined from time-of-flight neutron powder diffraction. The results indicate that MgSiN2, just like several other adamantine-type crystals, exhibits a relatively small thermal expansion coefficient at low

  7. Thermal expansion and decomposition of jarosite: a high-temperature neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwu [Los Alamos National Laboratory; Zhao, Yusheng [Los Alamos National Laboratory; Vogel, Sven C [Los Alamos National Laboratory; Hickmott, Donald D [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Hartl, Monika A [Los Alamos National Laboratory

    2009-01-01

    The structure of deuterated jarosite, KFe{sub 3}(SO{sub 4}){sub 2}(OD){sub 6}, was investigated using time-of-flight neutron diffraction up to its dehydroxylation temperature. Rietveld analysis reveals that with increasing temperature, its c dimension expands at a rate {approx}10 times greater than that for a. This anisotropy of thermal expansion is due to rapid increase in the thickness of the (001) sheet of [Fe(O,OH){sub 6}] octahedra and [SO{sub 4}] tetrahedra with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion, a = a{sub 0} + a{sub 1} T, where a{sub 0} = 1.01 x 10{sup -4} K{sup -1} and a{sub 1} = -1.15 x 10{sup -7} K{sup -2}. On heating, the hydrogen bonds, O1{hor_ellipsis}D-O3, through which the (001) octahedral-tetrahedral sheets are held together, become weakened, as reflected by an increase in the D{hor_ellipsis}O1 distance and a concomitant decrease in the O3-D distance with increasing temperature. On further heating to 575 K, jarosite starts to decompose into nanocrystalline yavapaiite and hematite (as well as water vapor), a direct result of the breaking of the hydrogen bonds that hold the jarosite structure together.

  8. Residual stress determination in thermally sprayed metallic deposits by neutron diffraction

    International Nuclear Information System (INIS)

    Keller, Thomas; Margadant, Nikolaus; Pirling, Thilo; Riegert-Escribano, Maria J.; Wagner, Werner

    2004-01-01

    Neutron diffraction was used to obtain spatially resolved strain and stress profiles in thermally sprayed metallic 'NiCrAlY' deposits (chemical composition 67 wt.% Ni, 22 wt.% Cr, 10 wt.% Al, 1 wt.% Y) and the underlying steel substrates. Samples of four different spray techniques were analyzed: atmospheric and water stabilized plasma spraying (APS and WSP), flame spraying (FS) and wire arc spraying (WAS). The results are quantitatively compared with the average in-plane residual stress determined by complementary bending tests and the hole drilling technique. While the stress profiles from the surface to the interface in the deposits are similar for all investigated spray techniques, their absolute values and gradients vary strongly. This is attributed to different quenching stresses from the impinging particles, different thermal histories the deposit/substrate systems undergo during the spraying and subsequent cooling, and also to different coating properties. In the water stabilized plasma sprayed and the wire arc sprayed deposits, a gradient in the stress-free lattice parameter was observed. Crack formation is found to be a dominant mechanism for stress relaxation in the surface plane

  9. Residual stress determination in thermally sprayed metallic deposits by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Thomas; Margadant, Nikolaus; Pirling, Thilo; Riegert-Escribano, Maria J.; Wagner, Werner

    2004-05-25

    Neutron diffraction was used to obtain spatially resolved strain and stress profiles in thermally sprayed metallic 'NiCrAlY' deposits (chemical composition 67 wt.% Ni, 22 wt.% Cr, 10 wt.% Al, 1 wt.% Y) and the underlying steel substrates. Samples of four different spray techniques were analyzed: atmospheric and water stabilized plasma spraying (APS and WSP), flame spraying (FS) and wire arc spraying (WAS). The results are quantitatively compared with the average in-plane residual stress determined by complementary bending tests and the hole drilling technique. While the stress profiles from the surface to the interface in the deposits are similar for all investigated spray techniques, their absolute values and gradients vary strongly. This is attributed to different quenching stresses from the impinging particles, different thermal histories the deposit/substrate systems undergo during the spraying and subsequent cooling, and also to different coating properties. In the water stabilized plasma sprayed and the wire arc sprayed deposits, a gradient in the stress-free lattice parameter was observed. Crack formation is found to be a dominant mechanism for stress relaxation in the surface plane.

  10. Report from the neutron diffraction work group

    International Nuclear Information System (INIS)

    1978-08-01

    This progress report of the neutron diffraction group at the Hahn Meitner Institute in Berlin comprises the following contributions: Three-dimensional critical properties of CsNiF 3 around the Neel point; Spin waves in CsNiF 3 with an applied magnetic field; Solitons in CsNiF 3 : Their experimental evidence and their thermodynamics; Neutron diffraction study of DAG at very low temperatures and in external magnetic field; Neutron diffraction investigation of tricritical behaviour in DyPO 4 ; Crystalline modifications and structural phase transitions of NaOH; Gitterdynamik von Cerhydrid; Investigation of the ferroelectric-ferroelastic phase transition in KH 2 PO 4 and RbH 2 PO 4 by means of γ-ray diffractometry; A γ-ray diffractometer for systematic measurements of absolute structure factors; Electron density in pyrite by combined γ-ray and neutron diffraction measurements: Thermal parameters from short wavelength neutron data; Accurate determination of temperature parameters from neutron diffraction data: Direct observation of the thermal diffuse scattering from silicon using perfect crystals; A Compton spectrometer for momentum density studies using 412 keV γ-radiation; Investigation of the electronic structure of Niobiumhydrides by means of gamma-ray Compton scattering; Interpretation of Compton profile data in position space; High resolution neutron scattering measurements on single crystals using a horizontally bent monochromator and a multidetecter; Statistical analysis of neutron diffraction studies of proteins. (orig.) [de

  11. Neutron diffraction and thermal studies of amorphous CS{sub 2} realised by low-temperature vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yamamuro, O.; Matsuo, T. [Osaka Univ., Dept. of Chemistry, Graduate School of Sciences (Japan); Onoda-Yamamuro, N. [Tokyo Denki Univ., College of Sciences and Technology (Japan); Takeda, K. [Naruto Univ., Dept. of Chemistry, Tokushima (Japan); Munemura, H.; Tanaka, S.; Misawa, M. [Niigata Univ. (Japan). Faculty of Science

    2003-08-01

    We have succeeded in preparing amorphous carbon disulphide (CS{sub 2}) by depositing its vapour on a cold substrate at 10 K. Complete formation of the amorphous state has been confirmed by neutron diffraction and differential thermal analysis (DTA). The amorphous sample crystallized at ca. 70 K, which is lower than the hypothetical glass transition temperature (92 K) estimated from the DTA data of the (CS{sub 2}){sub x}(S{sub 2}Cl{sub 2}){sub 1-x} binary mixture. CS{sub 2}, a symmetric linear tri-atomic molecule, is the simplest of the amorphized molecular substances whose structural and thermal information has been reported so far. Comparison of the static structure factors S(Q) has shown that the orientational correlation of CS{sub 2} molecules may be much stronger in the amorphous state than in the liquid state at higher temperature. (authors)

  12. Dynamical theory of neutron diffraction

    International Nuclear Information System (INIS)

    Sears, V.F.

    1978-01-01

    We present a review of the dynamical theory of neutron diffraction by macroscopic bodies which provides the theoretical basis for the study of neutron optics. We consider both the theory of dispersion, in which it is shown that the coherent wave in the medium satisfies a macroscopic one-body Schroedinger equation, and the theory of reflection, refraction, and diffraction in which the above equation is solved for a number of special cases of interest. The theory is illustrated with the help of experimental results obtained over the past 10 years by a number of new techniques such as neutron gravity refractometry. Pendelloesung interference, and neutron interferometry. (author)

  13. Neutron Powder Diffraction in Sweden

    International Nuclear Information System (INIS)

    Tellgren, R.

    1986-01-01

    Neutron powder diffraction in Sweden has developed around the research reactor R2 in Studsvik. The article describes this facility and presents a historical review of research results obtained. It also gives some ideas of plans for future development

  14. ALADIN - Advanced Laue Diffraction Instruments using Neutrons

    International Nuclear Information System (INIS)

    Lemee-Cailleau, M.H.; Ouladdiaf, B.; McIntyre, G.J.

    2011-01-01

    Laue diffraction techniques have proven to be very attractive to a broad user community interested in obtaining detailed structural information on very small single-crystal samples or needing data collection speeds comparable to those available with the powder diffraction technique. However our experience has clearly demonstrated the negative effect of up-stream monochromatic instruments on the quality of Laue data. In order to obtain Laue diffraction data with a statistical accuracy similar to that achieved on a monochromatic instrument (neutron or X-rays), the project ALADIN (for Advanced Laue Diffraction Instruments using Neutrons) aims to: -) construct a Laue-dedicated thermal neutron guide, with m=2 super-mirror coating, providing access to the desirable wavelength bandwidth; -) installation of one of the ILL Laue diffractometers (VIVALDI or CYCLOPS) on this new guide. (authors)

  15. Neutron diffraction studies of glasses

    International Nuclear Information System (INIS)

    Wright, A.C.

    1987-01-01

    A survey is given of the application of neutron diffraction to structural studies of oxide and halide glasses. As with crystalline materials, neutron and X-ray diffraction are the major structural probes for glasses and other amorphous solids, particularly in respect of intermediate range order. The glasses discussed mostly have structures which are dominated by a network in which the bonding is predominantly covalent. The examples discussed demonstrate the power of the neutron diffraction technique in the investigation of the structures of inorganic glasses. The best modern diffraction experiments are capable of providing accurate data with high real space resolution, which if used correctly, are an extremely fine filter for the various structural models proposed in the literature. 42 refs

  16. Neutron diffraction and oxide research

    International Nuclear Information System (INIS)

    Hunter, B.; Howard, C.J.; Kennedy, B.J.

    1999-01-01

    Oxide compounds form a large class of interesting materials that have a diverse range of mechanical and electronic properties. This diversity and its commercial implications has had a significant impact on physics research. This is particularly evident in the fields of superconductivity magnetoresistivity and ferroelectricity, where discoveries in the last 15 years have given rise to significant shifts in research activities. Historically, oxides have been studied for many years, but it is only recently that significant effort has been diverted to the study of oxide materials for their application to mechanical and electronic devices. An important property of such materials is the atomic structure, for the determination of which diffraction techniques are ideally suited. Recent examples of structure determinations using neutron diffraction in oxide based systems are high temperature superconductors, where oxygen defects are a key factor. Here, neutron diffraction played a major role in determining the effect of oxygen on the superconducting properties. Similarly, neutron diffraction has enjoyed much success in the determination of the structures of the manganate based colossal magnetoresistive (CMR) materials. In both these cases the structure plays a pivotal role in determining theoretical models of the electronic properties. The neutron scattering group at ANSTO has investigated several oxide systems using neutron powder diffraction. Two such systems are presented in this paper; the zirconia-based materials that are used as engineering materials, and the perovskite-based oxides that include the well known cuprate superconductors and the manganate CMR materials

  17. 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.)

  18. Neutron diffraction on pulsed sources

    International Nuclear Information System (INIS)

    Aksenov, V.L.; Balagurov, A.M.

    2016-01-01

    The possibilities currently offered and major scientific problems solved by time-of-flight neutron diffraction are reviewed. The reasons for the rapid development of the method over the last two decades has been mainly the emergence of third generation pulsed sources with a MW time-averaged power and advances in neutron-optical devices and detector systems. The paper discusses some historical aspects of time-of-flight neutron diffraction and examines the contribution to this method by F.L.Shapiro whose 100th birth anniversary was celebrated in 2015. The state of the art with respect to neutron sources for studies on output beams is reviewed in a special section. [ru

  19. Industrial applications of neutron diffraction

    International Nuclear Information System (INIS)

    Felcher, G.P.

    1989-01-01

    Neutron diffraction (or, to be more general, neutron scattering) is a most versatile and universal tool, which has been widely employed to probe the structure, the dynamics and the magnetism of condensed matter. Traditionally used for fundamental research in solid state physics, this technique more recently has been applied to problems of immediate industrial interest, as illustrated in examples covering the main fields of endeavour. 14 refs., 14 figs

  20. Structural and thermal properties of LaMnO3 from neutron diffraction and first principles studies

    International Nuclear Information System (INIS)

    Wdowik, Urszula D; Ouladdiaf, Bachir; Chatterji, Tapan

    2011-01-01

    Neutron diffraction experiments have been performed on powder samples of LaMnO 3 below and above the Jahn-Teller transition temperature of 750 K. Experimental investigations are assisted by density functional theory calculations. Theoretical studies are carried out for the orbitally ordered state of LaMnO 3 which allows one to compare the behavior of the orbitally ordered and disordered structures as a function of temperature. The temperature dependences of the structural parameters characterizing the Jahn-Teller distortions are reported and discussed. A gradual departure of the experimental data from theoretical predictions is observed above 650 K. In this range of temperatures, anions surrounding the Jahn-Teller active cations perform more isotropic thermal motion. The onset of structural phase transition induces a reduction of the crystal volume by about 0.4% which follows from the structural transformations yielding more regular oxygen octahedra formed above the phase transformation. It is found that above the Jahn-Teller transition the distortions of the MnO 6 octahedra are not completely removed. The non-vanishing distortions are accompanied by the lifted degeneracy of the Mn e g states. Weak residual distortions can be assigned to the short-range orbital order that persists within a local scale but it seems quenched on average giving rise to a disappearance of the long-range order coherency of the Jahn-Teller effect.

  1. Neutron diffraction study, magnetic properties and thermal stability of YMn2D6 synthesized under high deuterium pressure

    International Nuclear Information System (INIS)

    Paul-Boncour, V.; Filipek, S.M.; Dorogova, M.; Bouree, F.; Andre, G.; Marchuk, I.; Percheron-Guegan, A.; Liu, R.S.

    2005-01-01

    A new phase YMn 2 D 6 was synthesized by submitting YMn 2 to 1.7kbar deuterium pressure at 473K. According to X-ray and neutron powder diffraction experiments, YMn 2 D 6 crystallizes in the Fm3-bar m space group with a=6.709(1)A at 300K. The Y and half of the Mn atoms occupy statistically the 8c site whereas the other Mn atoms are located in 4a site and surrounded by 6D atoms (24e). This corresponds to a K 2 PtCl 6 -type structure with a partially disordered substructure which can be written as [YMn]MnH 6 . No ordered magnetic moment is observed in the NPD patterns and the magnetization measurements display a paramagnetic behavior. The study of the thermal stability by Differential Scanning Calorimetry and XRD experiments indicates that this phase decomposes in YD 2 and Mn at 625K, and is more stable than YMn 2 H 4.5

  2. Neutron diffraction and Vitamin E

    Energy Technology Data Exchange (ETDEWEB)

    Harroun, T A; Marquardt, D; Katsaras, J; Atkinson, J, E-mail: tharroun@brocku.ca

    2010-11-01

    It is generally accepted that neutron diffraction from model membrane systems is an effective biophysical technique for determining membrane structure. Here we describe an example of how deuterium labelling can elucidate the location of specific membrane soluble molecules, including a brief discussion of the technique itself. We show that deuterium labelled {alpha}-tocopherol sits upright in the bilayer, as might be expected, but at very different locations within the bilayer, depending on the degree of lipid chain unsaturation.

  3. Magnetic structures: neutron diffraction studies

    International Nuclear Information System (INIS)

    Bouree-Vigneron, F.

    1990-01-01

    Neutron diffraction is often an unequivocal method for determining magnetic structures. Here we present some typical examples, stressing the sequence through experiments, data analysis, interpretation and modelisation. Two series of compounds are chosen: Tb Ni 2 Ge 2 and RBe 13 (R = Gd, Tb, Dy, Ho, Er). Depending on the nature of the elements, the magnetic structures produced can be commensurate, incommensurate or even show a transition between two such phases as a function of temperature. A model, taking magnetic exchange and anisotropy into account, will be presented in the case of commensurate-incommensurate magnetic transitions in RBe 13

  4. Neutron-diffraction measurements of stress

    International Nuclear Information System (INIS)

    Holden, T.M.

    1995-01-01

    Experiments on bent steam-generator tubing have shown that different diffraction peaks, (1 1 1) or (0 0 2), give different results for the sign and magnitude of the stress and strain. From an engineering standpoint, the macroscopic stress field cannot be both positive and negative in the same volume, so this difference must be due to intergranular effects superposed on the macroscopic stress field. Uniaxial tensile test experiments with applied stresses beyond the 0.2% offset yield stress, help to understand this anomaly, by demonstrating the different strain response to applied stress along different crystallographic axes.When Zr-alloys are cooled from elevated temperatures, thermal stresses always develop, so that it is difficult to obtain a stress-free lattice spacing from which residual strains may be derived. From measurements of the temperature dependence of lattice spacing, the temperature at which the thermal stresses vanish may be found. From the lattice spacing at this temperature the stress-free lattice spacings at room temperature can be obtained readily.To interpret the measured strains in terms of macroscopic stress fields it is necessary to know the diffraction elastic constants. Neutron diffraction measurements of the diffraction elastic constants in a ferritic steel for the [1 1 0], [0 0 2] and [2 2 2] crystallographic axes, in directions parallel and perpendicular to the applied stress are compared with theoretical diffraction elastic constants. (orig.)

  5. Thermal neutron moderating device

    International Nuclear Information System (INIS)

    Takigami, Hiroyuki.

    1995-01-01

    In a thermal neutron moderating device, superconductive coils for generating magnetic fields capable of applying magnetic fields vertical to the longitudinal direction of a thermal neutron passing tube, and superconductive coils for magnetic field gradient for causing magnetic field gradient in the longitudinal direction of the thermal neutron passing tube are disposed being stacked at the outside of the thermal neutron passing tube. When magnetic field gradient is present vertically to the direction of a magnetic moment, thermal neutrons undergo forces in the direction of the magnetic field gradient in proportion to the magnetic moment. Then, the magnetic moment of the thermal neutrons is aligned with the direction vertical to the passing direction of the thermal neutrons, to cause the magnetic field gradient in the passing direction of the thermal neutrons. The speed of the thermal neutrons can be optionally selected and the wavelength can freely be changed by applying forces to the thermal neutrons and changing the extent and direction of the magnetic field gradient. Superconductive coils are used as the coils for generating magnetic fields and the magnetic field gradient in order to change extremely high energy of the thermal neutrons. (N.H.)

  6. Structure and Thermal Expansion of YSZ and La2Zr2O7 Above 1500°C from Neutron Diffraction on Levitated Samples

    International Nuclear Information System (INIS)

    Ushakov, Sergey V.; Neuefeind, Joerg C.

    2015-01-01

    High-temperature time-of-flight neutron diffraction experiments were performed in this paper on cubic yttria-stabilized zirconia (YSZ, 10 mol% YO 1.5 ) and lanthanum zirconate (LZ) prepared by laser melting. Three spheroids of each composition were aerodynamically levitated and rotated in argon flow and heated with a CO 2 laser. Unit cell, positional and atomic displacement parameters were obtained by Rietveld analysis. Below ~1650°C the mean thermal expansion coefficient (TEC) for YSZ is higher than for LZ (13 ± 1 vs. 10.3 ± 0.6) × 10 -6 /K. From ~1650°C to the onset of melting of LZ at ~2250°C, TEC for YSZ and LZ are similar and within (7 ± 2) × 10 -6 /K. LZ retains the pyrochlore structure up to the melting temperature with Zr coordination becoming closer to perfectly octahedral. Congruently melting LZ is La deficient. The occurrence of thermal disordering of oxygen sublattice (Bredig transition) in defect fluorite structure was deduced from the rise in YSZ TEC to ~25 × 10 -6 /K at 2350°C–2550°C with oxygen displacement parameters (U iso ) reaching 0.1 Å 2 , similar to behavior observed in UO 2 . Acquisition of powder-like high-temperature neutron diffraction data from solid-levitated samples is feasible and possible improvements are outlined. Finally, this methodology should be applicable to a wide range of materials for high-temperature applications.

  7. Neutron diffraction studies of magnetic materials

    International Nuclear Information System (INIS)

    James, W.J.

    1987-01-01

    The ability of neutron diffraction in determining the nature and extent of magnetic ordering is illustrated for the intermetallic compounds, Y/sub 6/(Fe,Mn)/sub 23/ and ErFe/sub 3/. Substitution with other 3d transition metals influences the Fe-Fe exchange forces such as to alter, sometimes considerably, the magnetic properties, e.g., local site magnetic anisotropies in Er)Fe,Ni)/sub 3/ and thermal expansion anomalies in the R/sub 2/)Fe,Co)/sub 14/B compounds. When the 3d atoms are near neighbors in the periodic chart, their nuclear scattering lengths for neutrons are sufficiently different to permit the detection of preferential occupation of the several nonequivalent crystallographic 3d metal sites, i.e., atomic ordering, present in the R/sub 6/M/sub 23/, and R/sub 2/Fe/sub 14/B structures

  8. Modern techniques of structural neutron diffraction

    International Nuclear Information System (INIS)

    Aksenov, V.L.; )

    1997-01-01

    Modern techniques of neutron diffraction for structural investigations are analyzed. The time-of-flight method and the reverse time-of-flight method are considered briefly. Characteristics of two-crystal and time-of-flight neutron diffractometers are compared. It is pointed that in the future, the great importance will be possessed the development of high-resolution Fourier neutron diffractometers [ru

  9. Thermal neutron polarisation

    International Nuclear Information System (INIS)

    Satya Murthy, N.S.; Madhava Rao, L.

    1984-01-01

    The basic principle for the production of polarised thermal neutrons is discussed and the choice of various crystal monochromators surveyed. Brief mention of broad-spectrum polarisers is made. The application of polarised neutrons to the study of magnetisation density distributions in magnetic crystals, the dynamic concept of polarisation, principle and use of polarisation analysis, the neutron spin-echo technique are discussed. (author)

  10. Dynamic study of the thermal stability of impure Ti3SiC2 in argon and air by neutron diffraction

    International Nuclear Information System (INIS)

    Oo, Z.; Low, I.M; O'Connor, B.H.

    2006-01-01

    The dynamic thermal stability and topotactic phase transition of impure Ti 3 SiC 2 in air and argon have been investigated by neutron diffraction (ND). In the presence of a low oxygen partial pressure as in argon, Ti 3 SiC 2 underwent a surface dissociation and TiC and/or Ti 5 Si 3 C were detected at 1200 deg. C. In contrast, oxide layers of rutile (TiO 2 ), TiO and cristobalite (SiO 2 ) were detected at ∼1000, 1250 and 1300 deg. C respectively when exposed to an oxygen-rich environment. Near-surface depth profiling of Ti 3 SiC 2 oxidized in air at 1200 deg. C by secondary ion mass spectroscopy (SIMS) has revealed a distinct gradation in phase composition at the interface of homogeneous rutile and heterogeneous cristobalite-rutile layers

  11. Dynamic study of the thermal stability of impure Ti 3SiC 2 in argon and air by neutron diffraction

    Science.gov (United States)

    Oo, Z.; Low, I. M.; O'Connor, B. H.

    2006-11-01

    The dynamic thermal stability and topotactic phase transition of impure Ti 3SiC 2 in air and argon have been investigated by neutron diffraction (ND). In the presence of a low oxygen partial pressure as in argon, Ti 3SiC 2 underwent a surface dissociation and TiC and/or Ti 5Si 3C were detected at 1200 °C. In contrast, oxide layers of rutile (TiO 2), TiO and cristobalite (SiO 2) were detected at ∼1000, 1250 and 1300 °C respectively when exposed to an oxygen-rich environment. Near-surface depth profiling of Ti 3SiC 2 oxidized in air at 1200 °C by secondary ion mass spectroscopy (SIMS) has revealed a distinct gradation in phase composition at the interface of homogeneous rutile and heterogeneous cristobalite-rutile layers.

  12. Solving crystal structures from neutron diffraction data

    International Nuclear Information System (INIS)

    Wilson, C.C.

    1987-07-01

    In order to pursue crystal structure determination using neutron diffraction data, and given the wide experience available of solving structures using X-ray data, the codes used in X-ray structural analysis should be adapted to the different requirements of a neutron experiment. Modifications have been made to a direct methods program MITHRIL and to a Patterson methods program PATMET to incorporate into these the features of neutron rather than X-ray diffraction. While to date these modifications have been fairly straightforward and many sophistications remain to be exploited, results obtained from the neutron versions of both programs are promising. (author)

  13. In Situ Study of Microstructure Evolution in Solidification of Hypereutectic Al-Si Alloys with Application of Thermal Analysis and Neutron Diffraction

    Science.gov (United States)

    Sediako, Dimitry G.; Kasprzak, Wojciech

    2015-09-01

    Understanding of the kinetics of solid-phase evolution in solidification of hypereutectic aluminum alloys is a key to control their as-cast microstructure and resultant mechanical properties, and in turn, to enhance the service characteristics of actual components. This study was performed to evaluate the solidification kinetics for three P-modified hypereutectic Al-19 pct Si alloys: namely, Al-Si binary alloy and with the subsequent addition of 2.8 pct Cu and 2.8 pct Cu + 0.7 pct Mg. Metallurgical evaluation included thermodynamic calculations of the solidification process using the FactSage™ 6.2 software package, as well as experimental thermal analysis, and in situ neutron diffraction. The study revealed kinetics of solid α-Al, solid Si, Al2Cu, and Mg2Si evolution, as well as the individual effects of Cu and Mg alloying additions on the solidification path of the Al-Si system. Various techniques applied in this study resulted in some discrepancies in the results. For example, the FactSage computations, in general, resulted in 281 K to 286 K (8 °C to 13 °C) higher Al-Si eutectic temperatures than the ones recorded in the thermal analysis, which are also ~278 K (~5 °C) higher than those observed in the in situ neutron diffraction. None of the techniques can provide a definite value for the solidus temperature, as this is affected by the chosen calculation path [283 K to 303 K (10 °C to 30 °C) higher for equilibrium solidification vs non-equilibrium] for the FactSage analysis; and further complicated by evolution of secondary Al-Cu and Mg-Si phases that commenced at the end of solidification. An explanation of the discrepancies observed and complications associated with every technique applied is offered in the paper.

  14. Applications of the fresnel diffraction of neutrons

    International Nuclear Information System (INIS)

    Klein, A.G.; Opat, G.I.

    1978-01-01

    The place of Fresnel diffraction in the overall scheme of neutron interference experiments is outlined and possible applications are discussed in the areas of: magnetic domain visualisation; measurement of nuclear scattering lengths with very small specimens; focussing of long wavelength neutron beams using zone plates

  15. Applications of the Fresnel diffraction of neutrons

    International Nuclear Information System (INIS)

    Klein, A.G.; Opat, G.I.

    1978-01-01

    The place of Fresnel diffraction in the overall scheme of neutron interference experiments is outlined and possible applications are discussed in the areas of: magnetic domain visualisation; measurement of nuclear scattering lengths with very small specimens; focussing of long wavelength neutron beams using zone plates

  16. Neutron forward diffraction by single crystal prisms

    Indian Academy of Sciences (India)

    We have derived analytic expressions for the deflection as well as transmitted fraction of monochromatic neutrons forward diffracted by a single crystal prism. In the vicinity of a Bragg reflection, the neutron deflection deviates sharply from that for an amorphous prism, exhibiting three orders of magnitude greater sensitivity to ...

  17. Anisotropic lattice thermal expansion of PbFeBO4: A study by X-ray and neutron diffraction, Raman spectroscopy and DFT calculations

    International Nuclear Information System (INIS)

    Murshed, M. Mangir; Mendive, Cecilia B.; Curti, Mariano; Nénert, Gwilherm; Kalita, Patricia E.; Lipinska, Kris; Cornelius, Andrew L.; Huq, Ashfia; Gesing, Thorsten M.

    2014-01-01

    Highlights: • Mullite-type PbFeBO 4 shows uni-axial negative coefficient of thermal expansion. • Anisotropic thermal expansion of the metric parameters was modeled using modified Grüneisen approximation. • The model includes harmonic, quasi-harmonic and intrinsic anharmonic contributions to the internal energy. • DFT calculation, temperature- and pressure-dependent Raman spectra help understand the phonon decay and associated anharmonicity. - Abstract: The lattice thermal expansion of mullite-type PbFeBO 4 is presented in this study. The thermal expansion coefficients of the metric parameters were obtained from composite data collected from temperature-dependent neutron and X-ray powder diffraction between 10 K and 700 K. The volume thermal expansion was modeled using extended Grüneisen first-order approximation to the zero-pressure equation of state. The additive frame of the model includes harmonic, quasi-harmonic and intrinsic anharmonic potentials to describe the change of the internal energy as a function of temperature. The unit-cell volume at zero-pressure and 0 K was optimized during the DFT simulations. Harmonic frequencies of the optical Raman modes at the Γ-point of the Brillouin zone at 0 K were also calculated by DFT, which help to assign and crosscheck the experimental frequencies. The low-temperature Raman spectra showed significant anomaly in the antiferromagnetic regions, leading to softening or hardening of some phonons. Selected modes were analyzed using a modified Klemens model. The shift of the frequencies and the broadening of the line-widths helped to understand the anharmonic vibrational behaviors of the PbO 4 , FeO 6 and BO 3 polyhedra as a function of temperature

  18. Neutron Larmor diffraction measurements for materials science

    International Nuclear Information System (INIS)

    Repper, J.; Keller, T.; Hofmann, M.; Krempaszky, C.; Petry, W.; Werner, E.

    2010-01-01

    Neutron Larmor diffraction (LD) is a high-resolution diffraction technique based on the Larmor precession of polarized neutrons. In contrast to conventional diffraction, LD does not depend on the accurate measurement of Bragg angles, and thus the resolution is independent of the beam collimation and monochromaticity. At present, a relative resolution for the determination of the crystal lattice spacing d of Δd/d∼10 -6 is achieved, i.e. at least one order of magnitude superior to conventional neutron or X-ray techniques. This work is a first step to explore the application of LD to high-resolution problems in the analysis of residual stresses, where both the accurate measurement of absolute d values and the possibility of measuring type II and III stresses may provide additional information beyond those accessible by conventional diffraction techniques. Data obtained from Inconel 718 samples are presented.

  19. Neutron Larmor diffraction measurements for materials science

    Energy Technology Data Exchange (ETDEWEB)

    Repper, J., E-mail: julia_repper@web.de [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), TU Muenchen, 85747 Garching (Germany); Keller, T. [Max-Planck-Institut fuer Festkoerperforschung, 70569 Stuttgart (Germany)] [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), TU Muenchen, 85747 Garching (Germany); Hofmann, M. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), TU Muenchen, 85747 Garching (Germany); Krempaszky, C. [Christian-Doppler-Labor fuer Werkstoffmechanik von Hochleistungslegierungen, TU Muenchen, 85747 Garching (Germany); Petry, W. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), TU Muenchen, 85747 Garching (Germany); Werner, E. [Lehrstuhl fuer Werkstoffkunde und Werkstoffmechanik, TU Muenchen, 85747 Garching (Germany)

    2010-05-15

    Neutron Larmor diffraction (LD) is a high-resolution diffraction technique based on the Larmor precession of polarized neutrons. In contrast to conventional diffraction, LD does not depend on the accurate measurement of Bragg angles, and thus the resolution is independent of the beam collimation and monochromaticity. At present, a relative resolution for the determination of the crystal lattice spacing d of {Delta}d/d{approx}10{sup -6} is achieved, i.e. at least one order of magnitude superior to conventional neutron or X-ray techniques. This work is a first step to explore the application of LD to high-resolution problems in the analysis of residual stresses, where both the accurate measurement of absolute d values and the possibility of measuring type II and III stresses may provide additional information beyond those accessible by conventional diffraction techniques. Data obtained from Inconel 718 samples are presented.

  20. Applications of neutron powder diffraction in materials research

    International Nuclear Information System (INIS)

    Kennedy, S.J.

    1996-01-01

    The aim of this article is to provide an overview of the applications of neutron powder diffraction in materials science. The technique is introduced with particular attention to comparison with the X-ray powder diffraction technique to which it is complementary. The diffractometers and special environment ancillaries operating around the HIFAR research reactor at the Australian Nuclear Science and Technology Organisation (ANSTO) are described. Applications of the technique which the advantage of the unique properties of thermal neutrons have been selected from recent materials studies undertaken at ANSTO

  1. Quantitative phase analysis by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang Hee; Song, Su Ho; Lee, Jin Ho; Shim, Hae Seop [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-06-01

    This study is to apply quantitative phase analysis (QPA) by neutron diffraction to the round robin samples provided by the International Union of Crystallography(IUCr). We measured neutron diffraction patterns for mixed samples which have several different weight percentages and their unique characteristic features. Neutron diffraction method has been known to be superior to its complementary methods such as X-ray or Synchrotron, but it is still accepted as highly reliable under limited conditions or samples. Neutron diffraction has strong capability especially on oxides due to its scattering cross-section of the oxygen and it can become a more strong tool for analysis on the industrial materials with this quantitative phase analysis techniques. By doing this study, we hope not only to do one of instrument performance tests on our HRPD but also to improve our ability on the analysis of neutron diffraction data by comparing our QPA results with others from any advanced reactor facilities. 14 refs., 4 figs., 6 tabs. (Author)

  2. Determination of textures by neutron diffraction

    International Nuclear Information System (INIS)

    Dervin, P.; Penelle, R.

    1989-01-01

    In virtue of the low absorption coefficient of most materials in regard to neutrons, neutron diffraction is particularly well adapted for high-precision characterizing of the gross texture of massive fine-grained or coarse-grained specimens of the order of the cubic centimeter. The firt part of this paper is devoted to a description of the distribution of crystalline orientations, and the second part to experimental identification of textures [fr

  3. An investigation of thermal and deformation properties of quartzite at the temperature interval of polymorphic α - β transition by neutron diffraction and acoustic emission

    International Nuclear Information System (INIS)

    Nikitin, A.N.; Vasin, R.N.; Balagurov, A.M.; Sobolev, G.A.; Ponomarev, A.V.

    2006-01-01

    The results of complex application of neutron diffraction and acoustic emission for investigation of the physical properties of synthetic quartz and natural quartzite at the temperature interval of α-β transition are given. During the experiments the quartzite sample was exposed to heating and also to uniaxial compression. The changes of the lattice spacings of quartzite at the temperature interval of 540-620 C were measured and values of lattice stresses were estimated; estimated lattice stresses several times exceed the applied stresses. It is found that short strong splashes of acoustic emission (AE) occurred when the phase transition was completed; the intensity of those splashes exceeds by two orders the level of AE, caused by the thermal bursting of the sample under heating up to the transition temperature. The assumption is placed that anomalous behaviour of quartz-containing rocks being under relatively small stresses near the phase transition temperature could cause the appearance of the concentrators of local stresses. These stresses are commensurable to the strength of quartz, and initiate the microcracking of the material

  4. Dynamic study of the thermal stability of impure Ti{sub 3}SiC{sub 2} in argon and air by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Oo, Z. [School of Engineering and Science, Curtin University of Technology, Sarawak Campus, CDT 250, 98009 Miri, Sarawak (Malaysia)]. E-mail: zeya.oo@curtin.edu.my; Low, I.M [School of Engineering and Science, Curtin University of Technology, Sarawak Campus, CDT 250, 98009 Miri, Sarawak (Malaysia); O' Connor, B.H. [Materials Research Group, Department of Applied Physics, Curtin University of Technology, GPO Box U1987, WA 6845 (Australia)

    2006-11-15

    The dynamic thermal stability and topotactic phase transition of impure Ti{sub 3}SiC{sub 2} in air and argon have been investigated by neutron diffraction (ND). In the presence of a low oxygen partial pressure as in argon, Ti{sub 3}SiC{sub 2} underwent a surface dissociation and TiC and/or Ti{sub 5}Si{sub 3}C were detected at 1200 deg. C. In contrast, oxide layers of rutile (TiO{sub 2}), TiO and cristobalite (SiO{sub 2}) were detected at {approx}1000, 1250 and 1300 deg. C respectively when exposed to an oxygen-rich environment. Near-surface depth profiling of Ti{sub 3}SiC{sub 2} oxidized in air at 1200 deg. C by secondary ion mass spectroscopy (SIMS) has revealed a distinct gradation in phase composition at the interface of homogeneous rutile and heterogeneous cristobalite-rutile layers.

  5. Neutron diffraction from lead germanate glasses

    International Nuclear Information System (INIS)

    Umesaki, Norimasa; Brunier, T.M.; Wright, A.C.; Hannon, A.C.; Scinclair, R.N.

    1993-01-01

    High resolution neutron diffraction data have been collected on the PbO-GeO 2 glasses and on GeO 2 for comparison. These neutron data have revealed the existence of 6-fold coordinated germanium (GeO 6 octahedra) by virtue of the shift in the first peak in the obtained total correlation function T(r) and increase in the coordination. The neutron results also indicate that PbO exits as PbO 4 pyramids, as found in the orthorhombic form of PbO crystal, in the studied PbO-GeO 2 glasses. (author)

  6. Studsvik thermal neutron facility

    International Nuclear Information System (INIS)

    Pettersson, O.A.; Larsson, B.; Grusell, E.; Svensson, P.

    1992-01-01

    The Studsvik thermal neutron facility at the R2-0 reactor originally designed for neutron capture radiography has been modified to permit irradiation of living cells and animals. A hole was drilled in the concrete shielding to provide a cylindrical channel with diameter of 25.3 cm. A shielding water tank serves as an entry holder for cells and animals. The advantage of this modification is that cells and animals can be irradiated at a constant thermal neutron fluence rate of approximately 10 9 n cm -2 s -1 (at 100 kW) without stopping and restarting the reactor. Topographic analysis of boron done by neutron capture autoradiography (NCR) can be irradiated under the same conditions as previously

  7. Crystallographic structures of absorbates and neutron diffraction

    International Nuclear Information System (INIS)

    Marti, C.; Thorel, P.

    1975-01-01

    The advantage of neutron diffraction is that it is possible to work at any pressure and therefore to study an adsorbant-adsorbate couple within a wide pressure and temperature range and at thermodynamic equilibrium. Nitrogen adsorbed on graphite and CF 4 adsorbed on graphite were measured [fr

  8. Neutron diffraction in a frustrated ferrite

    International Nuclear Information System (INIS)

    Mirebeau, I.; Iancu, G.; Gavoille, G.; Hubsch, J.

    1994-01-01

    The competition between a long range ordered ferrimagnetic lattice and small fluctuating clusters have been probed by neutron diffraction in a titanium magnesium frustrated ferrite. The description of the system is then compared to the predictions of several theoretical models for frustrated systems. 3 figs., 8 refs

  9. Neutron diffraction of γ-aluminium oxynitride

    NARCIS (Netherlands)

    Willems, H.X.; With, de G.; Metselaar, R.; Helmholdt, R.B.; Petersen, K.K.

    1993-01-01

    Neutron diffraction expts. were performed on Al oxynitride (Alon) powders with compns. corresponding to 67.5, 73 and 77.5 mol.% Al2O3. The 73 mol.% powder was produced by reacting Al2O3 and AlN powders for 3 h at 1750 Deg. After reaction the resultant powder was ground with a mortar and pestle to

  10. Neutron Powder Diffraction and Constrained Refinement

    DEFF Research Database (Denmark)

    Pawley, G. S.; Mackenzie, Gordon A.; Dietrich, O. W.

    1977-01-01

    The first use of a new program, EDINP, is reported. This program allows the constrained refinement of molecules in a crystal structure with neutron diffraction powder data. The structures of p-C6F4Br2 and p-C6F4I2 are determined by packing considerations and then refined with EDINP. Refinement is...

  11. Neutron diffraction from holographic gratings in PMMA

    International Nuclear Information System (INIS)

    Havermeyer, F.; Kraetzig, E.; Rupp, R.A.; Schubert, D.W.

    1999-01-01

    Complete text of publication follows. By definition photorefractive materials change the refractive index for light under the action of light. Using the spatially modulated light intensity pattern from the interference of two plane waves, volume phase gratings with accurately defined spacings can be produced. Depending on the material there are many physical origins for these gratings, but in most cases they are linked to a density modulation and, consequently, to a refractive index grating for neutrons. By diffraction of light or neutrons from such gratings even small refractive index changes down to Δn ∼ 10 -7 - 10 -9 can be measured. In our photopolymer system PMMA/MMA (poly(methyl methacrylate) with a content of 10-20% of the residual monomer methyl methacrylate) inhomogeneous illumination leads to local post-polymerisation processes of the residual monomer. The resulting light-optical refractive index grating is caused by the modulation of the monomer/polymer ratio as well as by the modulation of the total density. Only by the unique combination of methods for light and neutron diffraction, available at HOLONS (Holography and Neutron Scattering, instrument at the GKSS research centre), both contributions can be separated. We discuss the angular dependence of the neutron diffraction efficiency for weakly and strongly (efficiencies up to 60% have been achieved) modulated gratings and propose a simple model for the evaluation of the gratings. (author)

  12. Neutron Diffraction and Inorganic Materials Discovery

    International Nuclear Information System (INIS)

    Rosseinsky, M.J.

    2005-01-01

    Full text: The discovery of complex inorganic materials is an important academic and technological challenge because of the opportunities these systems offer for observation of new phenomena, and the questions they pose for fundamental understanding. This presentation will illustrate the key role of neutron powder diffraction in enabling the discovery of new classes of materials, and in evaluating their properties and the conditions under which they need to be processed to optimise their behaviour in devices for applications. New chemistry is illustrated by the transition metal oxide hydrides, where both structure and ionic mobility required neutron scattering characterisation. The relationship between chemistry, structure and properties will be addressed by considering the difficulties in inducing superconductivity in analogues of magnesium diboride. The role of both neutron and X-ray diffraction in evaluating the processing of microwave dielectric ceramics will be highlighted, with the discovery of new phases shown to be a useful bonus in this type of in-situ study. (author)

  13. Interphase microstress measurements in IN 718 by cold neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Repper, J.; Link, P.; Hofmann, M.; Petry, W. [TU Muenchen, Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Garching (Germany); Krempaszky, C. [TU Muenchen, Christian-Doppler-Labor fuer Werkstoffmechanik von Hochleistungslegierungen, Garching (Germany); Werner, E. [TU Muenchen, Lehrstuhl fuer Werkstoffkunde und Werkstoffmechanik, Garching (Germany)

    2010-06-15

    Thermal neutron diffraction is an important and reliable method for the investigation of microscopic stresses. The measurement of Bragg reflections caused by phases of small volume fractions, however, is often intricate due to low intensities and overlapping peaks. The wavelength range of cold neutrons allows to shift the Bragg reflections to larger scattering angles resulting in an increase of relative distances between Bragg reflections. The high resolution of cold neutron diffraction technique is demonstrated by in-situ load tests in which selected Bragg reflections caused by precipitates with small volume fractions in the precipitation strengthened alloy IN 718 are observed. The accumulated microstrains show marked differences in dependence of the precipitated phases within the matrix phase. (orig.)

  14. Applications of TOF neutron diffraction in archaeometry

    Energy Technology Data Exchange (ETDEWEB)

    Kockelmann, W. [Rutherford Appleton Laboratory, ISIS Facility, Chilton (United Kingdom); Siano, S.; Bartoli, L. [Istituto di Fisica Applicata - CNR, Sesto Fiorentino (Italy); Visser, D. [Rutherford Appleton Laboratory, ISIS Facility, Chilton (United Kingdom); Netherlands Organisation for Scientific Research (NWO), Den Haag (Netherlands); Hallebeek, P. [Netherlands Institute for Cultural Heritage (ICN), Amsterdam (Netherlands); Traum, R. [Kunsthistorisches Museum Wien, Muenzkabinett, Vienna (Austria); Linke, R.; Schreiner, M. [Akademie der Bildenden Kuenste, Institut fuer Wissenschaften und Technologien in der Kunst, Vienna (Austria); Kirfel, A. [Universitaet Bonn, Mineralogisch-Petrologisches Institut, Bonn (Germany)

    2006-05-15

    Neutron radiation meets the demand for a versatile diagnostic probe for collecting information from the interior of large, undisturbed museum objects or archaeological findings. Neutrons penetrate through coatings and corrosion layers deep into centimetre-thick materials, a property that makes them ideal for non-destructive examination of objects for which sampling is impractical or unacceptable. A particular attraction of neutron techniques for archaeologists and conservation scientists is the prospect of locating hidden materials and structures inside objects. Time-of-flight (TOF) neutron diffraction allows for the examination of mineral and metal phase contents, crystal structures, grain orientations, and microstructures as well as micro- and macro strains. A promising application is texture analysis which may provide clues to the deformation history of the material, and hence to specific working processes. Here we report on instructive examples of TOF neutron diffraction, including phase analyses of medieval Dutch tin-lead spoons, texture analyses of bronze specimens as well as of 16th-century silver coins. (orig.)

  15. Semiconductor Thermal Neutron Detector

    Directory of Open Access Journals (Sweden)

    Toru Aoki

    2014-02-01

    Full Text Available The  CdTe  and  GaN  detector  with  a  Gd  converter  have  been developed  and  investigated  as  a  neutron  detector  for neutron  imaging.  The  fabricated  Gd/CdTe  detector  with  the  25  mm  thick  Gd  was  designed  on  the  basis  of  simulation results  of  thermal  neutron  detection  efficiency  and  spatial  resolution.  The  Gd/CdTe  detector  shows  the  detection  of neutron  capture  gamma  ray  emission  in  the  155Gd(n,  g156Gd,  157Gd(n,  g158Gd  and  113Cd(n,  g114Cd  reactions  and characteristic X-ray emissions due to conversion-electrons generated inside the Gd film. The observed efficient thermal neutron detection with the Gd/CdTe detector shows its promise in neutron radiography application. Moreover, a BGaN detector has also investigated to separate neutron signal from gamma-ray clearly. 

  16. Neutron diffraction on polymorphic phases of phospholipids

    International Nuclear Information System (INIS)

    Adachi, Tomohiro; Furusaka, Michihiro; Otomo, Toshiya; Hatta, Ichiro

    2001-01-01

    Small angle neutron diffraction experiments were performed in DPPC and DPPC/cholesterol systems. We investigated the DPPC-d62 bilayers without cholesterol and the DPPC-d75 bilayers with 5 and 15 mol% cholesterol. For DPPC-d62 systems, in the gel and fluid phase, the reflections up to third order from lamellar structure were observed. Scattering length density profiles of these systems were generated. They show that the packing density of hydrocarbon chain in gel phase is higher than in fluid phase. We show that the neutron diffraction experiment is effective on observing the packing and the scattering length density of the hydrocarbon chain. On the other hand, for DPPC-d75/cholesterol systems, only the reflection from the ripple structure was observed. It shows that cholesterol is periodically localized in accordance with ripple structure forming a periodic bandlike structure parallel to a ridge of the ripple structure. (author)

  17. Powder Neutron Diffraction and Magnetic structures

    International Nuclear Information System (INIS)

    Vigneron, F.

    1986-01-01

    The determination of the magnetic structures of materials (ferromagnetic, antiferromagnetic, helimagnetic, .) can be achieved only by neutron diffraction. A general survey of the powder technique is given: 2-axis spectrometer and analysis of the magnetic data. For the REBe/sb13/ intermetallic compounds (RE = Rare Earth), commensurate and/or incommensurate magnetic structures are observed and discussed as a function of RE (Gd, Tb, Dy, Ho, Er)

  18. DNA hydration studied by neutron fiber diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, W.; Forsyth, V.T.; Mahendrasingam, A.; Langan, P.; Pigram, W.J. [Keele Univ. (United Kingdom)] [and others

    1994-12-31

    The development of neutron high angle fiber diffraction to investigate the location of water around the deoxyribonucleic acid (DNA) double-helix is described. The power of the technique is illustrated by its application to the D and A conformations of DNA using the single crystal diffractometer, D19, at the Institute Laue-Langevin, Grenoble and the time of flight diffractometer, SXD, at the Rutherford Appleton ISIS Spallation Neutron Source. These studies show the existence of bound water closely associated with the DNA. The patterns of hydration in these two DNA conformations are quite distinct and are compared to those observed in X-ray single crystal studies of two-stranded oligodeoxynucleotides. Information on the location of water around the DNA double-helix from the neutron fiber diffraction studies is combined with that on the location of alkali metal cations from complementary X-ray high angle fiber diffraction studies at the Daresbury Laboratory SRS using synchrotron radiation. These analyses emphasize the importance of viewing DNA, water and ions as a single system with specific interactions between the three components and provide a basis for understanding the effect of changes in the concentration of water and ions in inducing conformations] transitions in the DNA double-helix.

  19. TOF neutron diffraction study of archaeological ceramics

    International Nuclear Information System (INIS)

    Kockelmann, W.; Kirfel, A.

    1999-01-01

    Complete text of publication follows. The time-of flight (TOF) neutron diffractometer ROTAX [1] at ISIS has been used for identification and quantitative phase analysis of archaeological pottery. Neutron diffraction yields mineral phase fractions which, in parallel with information obtained from other archaeometric examination techniques, can provide a fingerprint that can be used to identify provenance and reconstruct methods of manufacturing of an archaeological ceramic product. Phase fractions obtained from a 13th century Rhenish stoneware jar compare well with those obtained from a powder sample prepared from the same fragment. This indicates that reliable results can be obtained by illuminating a large piece or even an intact ceramic object making TOF neutron diffraction a truly non-destructive examination technique. In comparison to X-ray diffraction, information from the bulk sample rather than from surface regions is obtained. ROTAX allows for a simple experimental set-up, free of sample movements. Programmes of archaeological study on ROTAX involve Russian samples (Upper-Volga culture, 5000-2000 BC), Greek pottery, (Agora/Athens, 500-300 BC), and medieval German earthenware and stoneware ceramics (Siegburg waster heap, 13-15th century). (author)

  20. DNA hydration studied by neutron fiber diffraction

    International Nuclear Information System (INIS)

    Fuller, W.; Forsyth, V.T.; Mahendrasingam, A.; Langan, P.; Pigram, W.J.

    1994-01-01

    The development of neutron high angle fiber diffraction to investigate the location of water around the deoxyribonucleic acid (DNA) double-helix is described. The power of the technique is illustrated by its application to the D and A conformations of DNA using the single crystal diffractometer, D19, at the Institute Laue-Langevin, Grenoble and the time of flight diffractometer, SXD, at the Rutherford Appleton ISIS Spallation Neutron Source. These studies show the existence of bound water closely associated with the DNA. The patterns of hydration in these two DNA conformations are quite distinct and are compared to those observed in X-ray single crystal studies of two-stranded oligodeoxynucleotides. Information on the location of water around the DNA double-helix from the neutron fiber diffraction studies is combined with that on the location of alkali metal cations from complementary X-ray high angle fiber diffraction studies at the Daresbury Laboratory SRS using synchrotron radiation. These analyses emphasize the importance of viewing DNA, water and ions as a single system with specific interactions between the three components and provide a basis for understanding the effect of changes in the concentration of water and ions in inducing conformations] transitions in the DNA double-helix

  1. Zeolite function studied by neutron diffraction

    International Nuclear Information System (INIS)

    Newsam, J.M.

    1988-01-01

    Some recent figures relating to industrial uses of zeolites are summarized. Recent advances in the application of neutron diffraction to zeolite science are overviewed, with particular emphasis on powder diffraction (PND) results. Single crystal neutron diffraction studies of some 17 hydrated natural and synthetic zeolites have now appeared and they provide a consistent picture of zeolite-water interactions. Complete PND studies of hydrated synthetic ABW- and SOD-framework zeolites have also been reported. Other PND studies have explored the structural consequences of non-framework cation exchange, of framework modification by dealumination, and of framework cation substitution. Relatively simple zeolite-hydrocarbon sorbate complexes that have been studied include benzene in zeolite Y, and benzene and pyridine in zeolite L. Areas that are well poised for further development include further extensions to lower symmetry systems, the use of PND data for zeolite structure solution, studies at elevated temperatures and pressures, and further studies of zeolite sorbate complexes. (author) 68 refs., 7 figs

  2. Workshop on industrial application of neutron diffraction. Stress measurement by neutron diffraction

    CERN Document Server

    Minakawa, N; Morii, Y; Oyama, Y

    2002-01-01

    This workshop was planned to make use of the neutron from the reactor and the pulse neutron source JSNS for the industrial world. Especially, this workshop focused on the stress measurement by the neutron diffraction and it was held on the Tokai JAERI from October 15 to 16, 2001. The participant total was 93 and 40 participated from the industrial world. The introduction of the residual stress development of measurement technique by the neutron diffraction method and a research of the measurement of the residual stress such as the nuclear reactor material, the ordinary structure material, the composite material, the quenching steel, the high strength material were presented and discussed in this workshop. Moreover, it was introduced for the industrial world that an internal stress measurement is important for development of new product or an improvement of a manufacturing process. The question from the industrial world about which can be measured the product form, the size, the measurement precision, the reso...

  3. Status of the Neutron Imaging and Diffraction Instrument IMAT

    Science.gov (United States)

    Kockelmann, Winfried; Burca, Genoveva; Kelleher, Joe F.; Kabra, Saurabh; Zhang, Shu-Yan; Rhodes, Nigel J.; Schooneveld, Erik M.; Sykora, Jeff; Pooley, Daniel E.; Nightingale, Jim B.; Aliotta, Francesco; Ponterio, Rosa C.; Salvato, Gabriele; Tresoldi, Dario; Vasi, Cirino; McPhate, Jason B.; Tremsin, Anton S.

    A cold neutron imaging and diffraction instrument, IMAT, is currently being constructed at the ISIS second target station. IMAT will capitalize on time-of-flight transmission and diffraction techniques available at a pulsed neutron source. Analytical techniques will include neutron radiography, neutron tomography, energy-selective neutron imaging, and spatially resolved diffraction scans for residual strain and texture determination. Commissioning of the instrument will start in 2015, with time-resolving imaging detectors and two diffraction detector prototype modules. IMAT will be operated as a user facility for material science applications and will be open for developments of time-of-flight imaging methods.

  4. Time-resolved Neutron Powder Diffraction

    International Nuclear Information System (INIS)

    Pannetier, J.

    1986-01-01

    The use of a high-flux neutron source together with a large position sensitive detector (PSD) allows a powder diffraction pattern to be recorded at a time-scale of a few minutes so that crystalline systems under non-equilibrium conditions may now conveniently be investigated. This introduces a new dimension into powder diffraction (the time and transient phenomena like heterogeneous chemical reactions can now be easily studied. The instrumental parameters relevant for the design of such time-dependent experiments are briefly surveyed and the current limits of the method are discussed. The applications are illustrated by two kinds of experiment in the field of inorganic solid state chemistry: true kinetic studies of heterogeneous chemical reactions and thermodiffractometry experiments

  5. Refractive and diffractive neutron optics with reduced chromatic aberration

    Energy Technology Data Exchange (ETDEWEB)

    Poulsen, S.O., E-mail: stefan.poulsen@northwestern.edu [NEXMAP, Department of Physics, Technical University of Denmark, Anker Engelunds Vej 1, 2800 Kgs. Lyngby (Denmark); Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Poulsen, H.F. [NEXMAP, Department of Physics, Technical University of Denmark, Anker Engelunds Vej 1, 2800 Kgs. Lyngby (Denmark); Bentley, P.M. [European Spallation Source ESS AB, Box 176, 221 00 Lund (Sweden)

    2014-12-11

    Thermal neutron beams are an indispensable tool in physics research. The spatial and the temporal resolution attainable in experiments are dependent on the flux and collimation of the neutron beam which remain relatively poor, even for modern neutron sources. These difficulties may be mitigated by the use of optics for focusing and imaging. Refractive and diffractive optical elements, e.g. compound refractive lenses and Fresnel zone plates, are attractive due to their low cost, and simple alignment. These optical elements, however, suffer from chromatic aberration, which limit their effectiveness to highly monochromatic beams. This paper presents two novel concepts for focusing and imaging non-monochromatic thermal neutron beams with well-known optical elements: (1) a fast mechanical transfocator based on a compound refractive lens, which actively varies the number of individual lenses in the beam path to focus and image a time-of-flight beam, and (2) a passive optical element consisting of a compound refractive lens, and a Fresnel zone plate, which may focus and image both continuous and pulsed neutron beams.

  6. Thermal neutron actinide data

    International Nuclear Information System (INIS)

    Tellier, H.

    1992-01-01

    During the 70's, the physicists involved in the cross section measurements for the low energy neutrons were almost exclusively interested in the resonance energy range. The thermal range was considered as sufficiently known. In the beginning of the 80's, reactor physicists had again to deal with the delicate problem of the power reactor temperature coefficient, essentially for the light water reactors. The measured value of the reactivity temperature coefficient does not agree with the computed one. The later is too negative. For obvious safety reasons, it is an important problem which must be solved. Several causes were suggested to explain this discrepancy. Among all these causes, the spectral shift in the thermal energy range seems to be very important. Sensibility calculations shown that this spectral shift is very sensitive to the shape of the neutron cross sections of the actinides for energies below one electron-volt. Consequently, reactor physicists require new and accurate measurements in the thermal and subthermal energy ranges. A part of these new measurement results were recently released and reviewed. The purpose of this study is to complete the preceding review with the new informations which are now available. In reactor physics the major actinides are the fertile nuclei, uranium 238, thorium 232 and plutonium 240 and the fissile nuclei, uranium 233, uranium 235 and plutonium 239. For the fertile nuclei the main datum is the capture cross section, for the fissile nuclei the data of interest are nu-bar, the fission and capture cross sections or a combination of these data such as η or α. In the following sections, we will review the neutron data of the major actinides for the energy below 1 eV

  7. 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.

  8. High resolution Neutron and Synchrotron Powder Diffraction

    International Nuclear Information System (INIS)

    Hewat, A.W.

    1986-01-01

    The use of high-resolution powder diffraction has grown rapidly in the past years, with the development of Rietveld (1967) methods of data analysis and new high-resolution diffractometers and multidetectors. The number of publications in this area has increased from a handful per year until 1973 to 150 per year in 1984, with a ten-year total of over 1000. These papers cover a wide area of solid state-chemistry, physics and materials science, and have been grouped under 20 subject headings, ranging from catalysts to zeolites, and from battery electrode materials to pre-stressed superconducting wires. In 1985 two new high-resolution diffractometers are being commissioned, one at the SNS laboratory near Oxford, and one at the ILL in Grenoble. In different ways these machines represent perhaps the ultimate that can be achieved with neutrons and will permit refinement of complex structures with about 250 parameters and unit cell volumes of about 2500 Angstrom/sp3/. The new European Synchotron Facility will complement the Grenoble neutron diffractometers, and extend the role of high-resolution powder diffraction to the direct solution of crystal structures, pioneered in Sweden

  9. Neutron diffraction studies of thin film multilayer structures

    International Nuclear Information System (INIS)

    Majkrzak, C.F.

    1985-01-01

    The application of neutron diffraction methods to the study of the microscopic chemical and magnetic structures of thin film multilayers is reviewed. Multilayer diffraction phenomena are described in general and in particular for the case in which one of the materials of a bilayer is ferromagnetic and the neutron beam polarized. Recent neutron diffraction measurements performed on some interesting multilayer systems are discussed. 70 refs., 5 figs

  10. Pulsed Neutron Powder Diffraction for Materials Science

    Science.gov (United States)

    Kamiyama, T.

    2008-03-01

    The accelerator-based neutron diffraction began in the end of 60's at Tohoku University which was succeeded by the four spallation neutron facilities with proton accelerators at the High Energy Accelerator Research Organization (Japan), Argonne National Laboratory and Los Alamos Laboratory (USA), and Rutherford Appleton Laboratory (UK). Since then, the next generation source has been pursued for 20 years, and 1MW-class spallation neutron sources will be appeared in about three years at the three parts of the world: Japan, UK and USA. The joint proton accelerator project (J-PARC), a collaborative project between KEK and JAEA, is one of them. The aim of the talk is to describe about J-PARC and the neutron diffractometers being installed at the materials and life science facility of J-PARC. The materials and life science facility of J-PARC has 23 neutron beam ports and will start delivering the first neutron beam of 25 Hz from 2008 May. Until now, more than 20 proposals have been reviewed by the review committee, and accepted proposal groups have started to get fund. Those proposals include five polycrystalline diffractometers: a super high resolution powder diffractometer (SHRPD), a 0.2%-resolution powder diffractometer of Ibaraki prefecture (IPD), an engineering diffractometers (Takumi), a high intensity S(Q) diffractometer (VSD), and a high-pressure dedicated diffractometer. SHRPD, Takumi and IPD are being designed and constructed by the joint team of KEK, JAEA and Ibaraki University, whose member are originally from the KEK powder group. These three instruments are expected to start in 2008. VSD is a super high intensity diffractometer with the highest resolution of Δd/d = 0.3%. VSD can measure rapid time-dependent phenomena of crystalline materials as well as glass, liquid and amorphous materials. The pair distribution function will be routinely obtained by the Fourier transiformation of S(Q) data. Q range of VSD will be as wide as 0.01 Å-1stress mapping inside

  11. The peak in neutron powder diffraction

    International Nuclear Information System (INIS)

    Laar, B. van; Yelon, W.B.

    1984-01-01

    For the application of Rietveld profile analysis to neutron powder diffraction data a precise knowledge of the peak profile, in both shape and position, is required. The method now in use employs a Gaussian shaped profile with a semi-empirical asymmetry correction for low-angle peaks. The integrated intensity is taken to be proportional to the classical Lorentz factor calculated for the X-ray case. In this paper an exact expression is given for the peak profile based upon the geometrical dimensions of the diffractometer. It is shown that the asymmetry of observed peaks is well reproduced by this expression. The angular displacement of the experimental profile with respect to the nominal Bragg angle value is larger than expected. Values for the correction to the classical Lorentz factor for the integrated intensity are given. The exact peak profile expression has been incorporated into a Rietveld profile analysis refinement program. (Auth.)

  12. In-situ neutron diffraction measurements of temperature and stresses during friction stir welding of 6061-T6 aluminum alloy

    International Nuclear Information System (INIS)

    Woo, Wan Chuck; Feng, Zhili; Wang, Xun-Li; Brown, D.W.; Clausen, B.; An, Ke; Choo, Hahn; Hubbard, Camden R.; David, Stan A.

    2007-01-01

    The evolution of temperature and thermal stresses during friction stir welding of Al6061-T6 was investigated by means of in-situ, time-resolved neutron diffraction technique. A method is developed to deconvolute the temperature and stress from the lattice spacing changes measured by neutron diffraction. The deep penetration capability of neutrons made it possible for the first time to obtain the temperature and thermal stresses inside a friction stir weld

  13. Dynamical neutron diffraction by curved crystals in the Laue geometry

    International Nuclear Information System (INIS)

    Albertini, G.; Melone, S.; Lagomarsino, S.; Mazkedian, S.; Puliti, P.; Rustichelli, F.

    1977-01-01

    The Taupin dynamical theory of X-ray diffraction by deformed crystals which was previously extended to the neutron diffraction by curved crystals in the Bragg geometry, is applied to calculate neutron diffraction patterns in the Laue geometry. The theoretical results are compared with experimental data on curved silicon crystals. The agreement is quite satisfactory. In the second part a simple model recently presented to describe neutron diffraction properties in the Bragg case is extended to the Laue case. The predictions of such a model are in satisfactory agreement with the rigorous theory and the experimental results. (author)

  14. Neutron diffraction technique as a method for material studies

    International Nuclear Information System (INIS)

    Belhorma, B.; Labrim, H.; Gandou, Z.

    2010-01-01

    The Morocco's first Nuclear Research has been constructed in CNESTEN. The reactor divergence has been tested, and the nominal power of 2MW was successfully achieved. The reactor has 4 beam ports two of them are projected for neutron scattering. Such technique allows studying the crystallographic and magnetic structures of materials using the thermal neutrons produced in the reactor. the powder diffractometer has been designed. Component reception and installation procedures are in progress. The second experiment consists on small angle neutron scattering that allows the study of soft matter and polymers in the range of 1-50 nm. The third technique that can complete the two previous is the 4-circle neutron spectrometry which is designed mainly to study structural properties of the mono-crystalline material and texture.This technique is complementary to the X-ray diffraction already available in CNESTEN. Some applications of this technique are: --to determine the crystallographic and magnetic structure of polycrystalline materials.-- to study the texture in metals and alloys.-- to perform holography measurement

  15. Applications of thermal neutron scattering in biology, biochemistry and biophysics

    International Nuclear Information System (INIS)

    Worcester, D.L.

    1977-01-01

    Biological applications of thermal neutron scattering have increased rapidly in recent years. The following categories of biological research with thermal neutron scattering are presently identified: crystallography of biological molecules; neutron small-angle scattering of biological molecules in solution (these studies have already included numerous measurements of proteins, lippoproteins, viruses, ribosomal subunits and chromatin subunit particles); neutron small-angle diffraction and scattering from biological membranes and membrane components; and neutron quasielastic and inelastic scattering studies of the dynamic properties of biological molecules and materials. (author)

  16. Enstatite, Mg2Si2O6: A neutron diffraction refinement of the crystal structure and a rigid-body analysis of the thermal vibration

    International Nuclear Information System (INIS)

    Ghose, S.; Schomaker, V.; McMullan, R.K.

    1986-01-01

    Synthetic enstatite, Mg 2 Si 2 O 6 , is orthorhombic, space group Pbca, with eight formula units per cell and lattice parameters a = 18.235(3), b = 8.818(1), c = 5.179(1) A at 23 0 C. A least-squares structure refinement based on 1790 neutron intensity data converged with an agreement factor R(F 2 ) = 0.032, yielding Mg-O and Si-O bond lengths with standard deviations of 0.0007 and 0.0008 A, respectively. The variations observed in the Si-O bond lengths within the silicate tetrahedra A and B are caused by the differences in primary coordination of the oxygen atoms and the proximity of the magnesium ions to the silicon atoms. The latter effect is most pronounced for the bridging bonds of tetrahedron. A. The smallest O-Si-O angle is the result of edge-sharing by the Mg(2) octahedron and the A tetrahedron. An analysis of rigid-body thermal vibrations of the two crystallographically independent [SiO 4 ] tetrahedra indicates considerable librational motion, leading to a thermal correction of apparent Si-O bond lengths as large as +0.002 A at room temperature. (orig.)

  17. A new bridge technique for neutron tomography and diffraction measurements

    International Nuclear Information System (INIS)

    Burca, G.; James, J.A.; Kockelmann, W.; Fitzpatrick, M.E.; Zhang, S.Y.; Hovind, J.; Langh, R. van

    2011-01-01

    An attractive feature of neutron techniques is the ability to identify hidden materials and structures inside engineering components and objects of art and archaeology. Bearing this in mind we are investigating a new technique, 'Tomography Driven Diffraction' (TDD), that exploits tomography data to guide diffraction experiments on samples with complex structures and shapes. The technique can be used utilising combinations of individual tomography and diffraction instruments, such as NEUTRA (PSI, CH) and ENGIN-X (ISIS, UK), but is also suitable for new combined imaging and diffraction instruments such as the JEEP synchrotron engineering instrument (DIAMOND, UK) and the proposed IMAT neutron imaging and diffraction instrument (ISIS, UK).

  18. Bibliography for thermal neutron scattering

    International Nuclear Information System (INIS)

    Sakamoto, M.; Chihara, J.; Nakahara, Y.; Kadotani, H.; Sekiya, T.

    1976-12-01

    It contains bibliographical references to measurements, calculations, reviews and basic studies on thermal neutron scatterings and dynamical properties of condensed matter. About 2,700 documents up to the end of 1975 are covered. (auth.)

  19. Experimental technique of stress analyses by neutron diffraction

    International Nuclear Information System (INIS)

    Sun, Guangai; Chen, Bo; Huang, Chaoqiang

    2009-09-01

    The structures and main components of neutron diffraction stress analyses spectrometer, SALSA, as well as functions and parameters of each components are presented. The technical characteristic and structure parameters of SALSA are described. Based on these aspects, the choice of gauge volume, method of positioning sample, determination of diffraction plane and measurement of zero stress do are discussed. Combined with the practical experiments, the basic experimental measurement and the related settings are introduced, including the adjustments of components, pattern scattering, data recording and checking etc. The above can be an instruction for stress analyses experiments by neutron diffraction and neutron stress spectrometer construction. (authors)

  20. Thermal neutron source study

    International Nuclear Information System (INIS)

    Holden, T.M.

    1983-05-01

    The value of intense neutron beams for condensed matter research is discussed with emphasis on the complementary nature of steady state and pulsed neutron sources. A large body of information on neutron sources, both existing and planned, is then summarized under four major headings: fission reactors, electron accelerators with heavy metal targets, pulsed spallation sources and 'steady state' spallation sources. Although the cost of a spallation source is expected to exceed that of a fission reactor of the same flux by a factor of two, there are significant advantages for a spallation device such as the proposed Electronuclear Materials Test Facility (EMTF)

  1. Structural studies of liquid alcohols by neutron diffraction

    International Nuclear Information System (INIS)

    Montague, D.G.; Cummings, S.

    1984-01-01

    Neutron diffraction measurements have been made on methyl alcohol at room temperature for an incident wavelength of 0.94 A. Cross sections have been obtained for CD 3 OD, CD 3 OH, and mixtures of these compounds. These data are subtracted to obtain the separated structure factors for intermolecular H 0 H 0 , the hydroxyl components, and the non-hydroxyl components. The Fourier transformations of the structure factors show components of both intra- and intermolecular distribution functions. Width parameters obtained from model fits are too large for thermal vibrations and are interpreted as geometrical broadening due to the stretching of bonds, variations in bond angles, and rotation of the methyl group. Differences in the real space distribution function between hydrogen and deuterium are noted. (author)

  2. Polarised neutron diffraction studies on weak ferromagnetism - a survey

    International Nuclear Information System (INIS)

    Radhakrishna, P.

    1982-10-01

    The physical basis of the phenomenon of weak ferromagnetism in certain antiferromagnetic insulators is briefly discussed. A survey of the contributions of polarised neutron diffraction towards the elucidation of different aspects of this field is presented

  3. Future directions in high-pressure neutron diffraction

    Science.gov (United States)

    Guthrie, M.

    2015-04-01

    The ability to manipulate structure and properties using pressure has been well known for many centuries. Diffraction provides the unique ability to observe these structural changes in fine detail on lengthscales spanning atomic to nanometre dimensions. Amongst the broad suite of diffraction tools available today, neutrons provide unique capabilities of fundamental importance. However, to date, the growth of neutron diffraction under extremes of pressure has been limited by the weakness of available sources. In recent years, substantial government investments have led to the construction of a new generation of neutron sources while existing facilities have been revitalized by upgrades. The timely convergence of these bright facilities with new pressure-cell technologies suggests that the field of high-pressure (HP) neutron science is on the cusp of substantial growth. Here, the history of HP neutron research is examined with the hope of gleaning an accurate prediction of where some of these revolutionary capabilities will lead in the near future. In particular, a dramatic expansion of current pressure-temperature range is likely, with corresponding increased scope for extreme-conditions science with neutron diffraction. This increase in coverage will be matched with improvements in data quality. Furthermore, we can also expect broad new capabilities beyond diffraction, including in neutron imaging, small angle scattering and inelastic spectroscopy.

  4. Applications of thermal neutron scattering

    International Nuclear Information System (INIS)

    Kostorz, G.

    1978-01-01

    Although in the past neutrons have been used quite frequently in the study of condensed matter, a more recent development has lead to applications of thermal neutron scattering in the investigation of more practical rather than purely academic problems. Physicists, chemists, materials scientists, biologists, and others have recognized and demonstrated that neutron scattering techniques can yield supplementary information which, in many cases, could not be obtained with other methods. The paper illustrates the use of neutron scattering in these areas of applied research. No attempt is made to present all the aspects of neutron scattering which can be found in textbooks. From the vast amount of experimental data, only a few examples are presented for the study of structure and atomic arrangement, ''extended'' structure, and dynamic phenomena in substances of current interest in applied research. (author)

  5. Investigation of Acrylic Acid at High Pressure using Neutron Diffraction

    DEFF Research Database (Denmark)

    Johnston, Blair F.; Marshall, William G.; Parsons, Simon

    2014-01-01

    This article details the exploration of perdeuterated acrylic acid at high pressure using neutron diffraction. The structural changes that occur in acrylic acid-d4 are followed via diffraction and rationalised using the Pixel method. Acrylic acid undergoes a reconstructive phase transition to a new...

  6. Prospect for application of compact accelerator-based neutron source to neutron engineering diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Yoshimasa, E-mail: yoshimasa.ikeda@riken.jp [Center for Advanced Photonics, RIKEN, Wako, Saitama 351-0198 (Japan); Taketani, Atsushi; Takamura, Masato; Sunaga, Hideyuki [Center for Advanced Photonics, RIKEN, Wako, Saitama 351-0198 (Japan); Kumagai, Masayoshi [Faculty of Engineering, Tokyo City University, Setagaya, Tokyo 158-8857 (Japan); Oba, Yojiro [Research Reactor Institute, Kyoto University, Kumatori, Osaka 590-0494 (Japan); Otake, Yoshie [Center for Advanced Photonics, RIKEN, Wako, Saitama 351-0198 (Japan); Suzuki, Hiroshi [Materials Sciences Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

    2016-10-11

    A compact accelerator-based neutron source has been lately discussed on engineering applications such as transmission imaging and small angle scattering as well as reflectometry. However, nobody considers using it for neutron diffraction experiment because of its low neutron flux. In this study, therefore, the neutron diffraction experiments are carried out using Riken Accelerator-driven Compact Neutron Source (RANS), to clarify the capability of the compact neutron source for neutron engineering diffraction. The diffraction pattern from a ferritic steel was successfully measured by suitable arrangement of the optical system to reduce the background noise, and it was confirmed that the recognizable diffraction pattern can be measured by a large sampling volume with 10 mm in cubic for an acceptable measurement time, i.e. 10 min. The minimum resolution of the 110 reflection for RANS is approximately 2.5% at 8 μs of the proton pulse width, which is insufficient to perform the strain measurement by neutron diffraction. The moderation time width at the wavelength corresponding to the 110 reflection is estimated to be approximately 30 μs, which is the most dominant factor to determine the resolution. Therefore, refinements of the moderator system to decrease the moderation time by decreasing a thickness of the moderator or by applying the decoupler system or application of the angular dispersive neutron diffraction technique are important to improve the resolution of the diffraction experiment using the compact neutron source. In contrast, the texture evolution due to plastic deformation was successfully observed by measuring a change in the diffraction peak intensity by RANS. Furthermore, the volume fraction of the austenitic phase in the dual phase mock specimen was also successfully evaluated by fitting the diffraction pattern using a Rietveld code. Consequently, RANS has been proved to be capable for neutron engineering diffraction aiming for the easy access

  7. Measuring thermal neutron characteristics

    International Nuclear Information System (INIS)

    Johnstone, C.W.; Jacobson, L.A.

    1983-01-01

    A method for providing a background-compensated measurement of the level of inducted radiation within an earth formation is claimed. The formation is irradiated with a discrete burst of neutrons and the level of radiation in the formation measured. The level of background radiation is then measured. An average level of both measurements is obtained

  8. An automatic control unit for A neutron diffraction crystal spectrometer

    International Nuclear Information System (INIS)

    Adib, M.; Abbas, Y.; Mostafa, M.; Hamouda, I.

    1982-01-01

    An automatic transistorized unit has been designed and constructed to control the operation of the double axis crystal spectrometer installed in front of one of the horizontal channels of the ET-RR-1 reactor. The function of the automatic unit is to store the diffracted neutrons at a certain angle with respect to the direction of the incident neutron beam in a selected channel of a 1024-multichannel analyzer for a certain preadjusted time period. AT the end of this time period the unit rotates the spectrometer's arm to another angle, selects the next channel of the MCA and provides the measurement of the diffracted neutron for the same time period. Such a sequence is repeated automatically over all angles required for the neutron diffraction pattern of the sample under investigation. As a result, the stored information at the MCA provides the neutron diffraction pattern as a function of channel number, where each channel corresponds to a certain scattering angle. The stored distribution at MCA can be obtained through the analyzer read out unit. The designed automatic unit has the possibility of providing the neutron diffraction pattern using a 6-digit scaler and a printer

  9. Automatic control unit for A neutron diffraction crystal spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Adib, M.; Abbas, Y.; Mostafa, M.; Hamouda, I.

    1982-01-01

    An automatic transistorized unit has been designed and constructed to control the operation of the double axis crystal spectrometer installed in front of one of the horizontal channels of the ET-RR-1 reactor. The function of the automatic unit is to store the diffracted neutrons at a certain angle with respect to the direction of the incident neutron beam in a selected channel of a 1024-multichannel analyzer for a certain preadjusted time period. AT the end of this time period the unit rotates the spectrometer's arm to another angle, selects the next channel of the MCA and provides the measurement of the diffracted neutron for the same time period. Such a sequence is repeated automatically over all angles required for the neutron diffraction pattern of the sample under investigation. As a result, the stored information at the MCA provides the neutron diffraction pattern as a function of channel number, where each channel corresponds to a certain scattering angle. The stored distribution at MCA can be obtained through the analyzer read out unit. The designed automatic unit has the possibility of providing the neutron diffraction pattern using a 6-digit scaler and a printer.

  10. Measurement of the velocity of sound in crystals by pulsed neutron diffraction

    International Nuclear Information System (INIS)

    Willis, B.T.M.; Carlile, C.J.; Ward, R.C.; David, W.I.F.; Johnson, M.W.

    1986-03-01

    The diffraction method of observing elementary excitations in crystals has been applied to the study of one-phonon thermal diffuse scattering from pyrolytic graphite on a high resolution pulsed neutron diffractometer. The variation of the phase velocity of sound as a function of direction in the crystal and efficient method of determining sound velocities in crystals under extreme conditions. (author)

  11. High temperature neutron diffraction study of LaPO4

    International Nuclear Information System (INIS)

    Mishra, S.K.; Mittal, R.; Ningthoujam, R.S.; Vatsa, R.K.; Hansen, T.

    2016-01-01

    We report high temperature powder neutron diffractions study in LaPO 4 using high-flux D20 neutron diffractometer in the Institut Laue-Langevin, France. The measurements were carried out in high resolution mode (incident neutron wavelength 1.36 A) at various temperature upto 900°C. CarefuI inspection of temperature dependence of diffraction data showed appearance and disappearance of certain Bragg's reflections above 1273 K. It is a signature of structural phase transition. Rietveld refinement of the powder diffraction data revealed that diffraction patterns at and above 800°C could be indexed using the monoclinic structure with P21/n space group. Detail analysis for identify the water molecules is under investigation. (author)

  12. Study of ethanol-lysozyme interactions using neutron diffraction

    International Nuclear Information System (INIS)

    Lehmann, M.S.; Mason, S.A.; McIntyre, G.J.

    1985-01-01

    Single-crystal neutron diffraction has been used to observe the interactions between deuterated ethanol (CD3CD2OH) and lysozyme in triclinic crystals of hen egg white lysozyme soaked in 25% (v/v) ethanol solutions. A total of 6047 observed reflections to a resolution of 2 A were used, and 13 possible ethanol sites were identified. The three highest occupied sites are close to locations for bromoethanol found in an earlier study by Yonath et al. [Yonath, A., Podjarny, A., Honig, B., Traub, W., Sielecki, A., Herzberg, O., and Moult, J. (1978) Biophys. Struct. Mech. 4, 27-36]. Structure refinements including a model for the flat solvent lead to a final crystallographic agreement factor of 0.097. Comparison with earlier neutron studies on triclinic lysozyme showed that neither the molecular structure nor the thermal motions were affected significantly by the ethanol. A detailed analysis of the ethanol-lysozyme contacts showed 61% of these to be with hydrophobic sites, in agreement with the dominant hydrophobic nature of ethanol. This, together with the fact that the molecular structure of lysozyme is not perturbed, suggests a model for denaturation of lysozyme by alcohol, which proceeds via a dehydration of the protein at high alcohol concentration

  13. Bibliography for thermal neutron scattering

    International Nuclear Information System (INIS)

    Sakamoto, Masanobu; Chihara, Junzo; Gotoh, Yorio; Kadotani, Hiroyuki; Sekiya, Tamotsu.

    1979-09-01

    Bibliographic references are given for measurements, calculations, reviews and basic studies of thermal neutron scattering and dynamical properties of condensed matter. This is the sixth edition covering 3,326 articles collected up to 1978. The edition being the final issue of the present bibliography series, a forthcoming edition will be published in a new form of bibliography. (author)

  14. Extinction correction in white X-ray and neutron diffraction

    International Nuclear Information System (INIS)

    Tomiyoshi, S.; Yamada, M.; Watanabe, H.

    1980-01-01

    Extinction effects in white-beam X-ray and neutron diffraction are considered. In white-beam diffraction, a small deviation of the wavelength from the Bragg condition Δlambda is a variable which represents the line profile of the diffraction peaks, so that by using the new parameter Δlambda the theory is converted to one in white-beam diffraction. It is shown that for a convex crystal, primary extinction agrees with the results calculated already for monochromatic diffraction. The same relation is shown to hold in secondary extinction. It is concluded that extinction theory derived for monochromatic diffraction is applicable without any modification in white-beam diffraction. (Auth.)

  15. Kinetic neutron diffraction and SANS studies of phase formation in bioactive machinable glass ceramics

    International Nuclear Information System (INIS)

    Bentley, P M; Kilcoyne, S H; Bubb, N L; Ritter, C; Dewhurst, C D; Wood, D J

    2007-01-01

    Bioactive fluormica-fluorapatite glass-ceramic materials offer a very encouraging solution to the problem of efficient restoration and reconstruction of hard tissues. To produce material with the desired crystalline phases, a five-stage heat treatment must be performed. This thermal processing has a large impact on the microstructure and ultimately the final mechanical properties of the materials. We have examined the thermal processing of one of our most promising machinable biomaterials, using time-resolved small angle neutron scattering and neutron diffraction to study the nucleation and growth of crystallites. The processing route had already been optimized by studying the properties of quenched samples using x-ray diffraction, mechanical measurements and differential thermal analysis. However these results show that the heat treatment can be further optimized in terms of crystal nucleation, and we show that these techniques are the only methods by which a truly optimized thermal processing route may be obtained

  16. 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.

  17. Fail-safe neutron shutter used for thermal neutron radiography

    International Nuclear Information System (INIS)

    Sachs, R.D.; Morris, R.A.

    1976-11-01

    A fail-safe, reliable, easy-to-use neutron shutter was designed, built, and put into operation at the Omega West Reactor, Los Alamos Scientific Laboratory. The neutron shutter will be used primarily to perform thermal neutron radiography, but is also available for a highly collimated source of thermal neutrons [neutron flux = 3.876 x 10 6 (neutrons)/(cm 2 .s)]. Neutron collimator sizes of either 10.16 by 10.16 cm or 10.16 by 30.48 cm are available

  18. Set of thermal neutron-scattering experiments for the Weapons Neutron Research Facility

    International Nuclear Information System (INIS)

    Brugger, R.M.

    1975-12-01

    Six classes of experiments form the base of a program of thermal neutron scattering at the Weapons Neutron Research (WNR) Facility. Three classes are to determine the average microscopic positions of atoms in materials and three are to determine the microscopic vibrations of these atoms. The first three classes concern (a) powder sample neutron diffraction, (b) small angle scattering, and (c) single crystal Laue diffraction. The second three concern (d) small kappa inelastic scattering, (e) scattering surface phonon measurements, and (f) line widths. An instrument to couple with the WNR pulsed source is briefly outlined for each experiment

  19. Characterization of a polychromatic neutron beam diffracted by pyrolytic graphite crystals

    CERN Document Server

    Byun, S H; Choi, H D

    2002-01-01

    The beam spectrum for polychromatic neutrons diffracted by pyrolytic graphite crystals was characterized. The theoretical beam spectrum was obtained using the diffraction model for a mosaic crystal. The lattice vibration effects were included in the calculation using the reported vibration amplitude of the crystal and the measured time-of-flight spectra in the thermal region. The calculated beam spectrum was compared with the results obtained in the absence of thermal motion. The lattice vibration effects became more important for the higher diffraction orders and a large decrease in the neutron flux induced by the vibrations was identified in the epithermal region. The validity of the beam spectrum was estimated by comparing with the effective quantities determined from prompt gamma-ray measurements and Cd-ratios measured both for 1/nu and non-1/nu nuclides.

  20. Neutron diffraction measurements of residual stresses in NPP construction materials

    International Nuclear Information System (INIS)

    Hinca, R.; Bokuchava, G.

    2001-01-01

    Neutron diffraction is one of the most powerful methods for condensed matter studies. This method is used for non-destructive determination of residual stresses in material. The fundamental aspects of neutron diffraction are discussed, together with a brief description of the experimental facility. The principal advantage of using neutrons rather than the more conventional X-rays is the fact that neutron can penetrate deeply (2-4 cm for steel and more than 10 cm for aluminium) into metals to determine internal parameters within the bulk of materials. We present results of measurements residual stresses in NPP construction material - austenitic stainless steel (Cr-18%, Ni-10%, Ti-1%) coated with high-nickel alloy. (authors)

  1. The structure of pumice by neutron diffraction

    International Nuclear Information System (INIS)

    Floriano, M.A.; Venezia, A.M.; Deganello, G.; Svensson, E.C.; Root, J.H.

    1994-01-01

    Small-angle neutron scattering (SANS) and wide-angle neutron scattering (WANS) measurements on pumice, an amorphous natural aluminosilicate used as support for metals in the preparation of catalysts, are reported. The SANS spectrum indicates the presence of a broad size distribution of pores and the absence of volume fractality. Surface fractality, however, cannot be ruled out. The structure of pumice, suggested by the pair-correlation function derived from the WANS spectrum and simulated by a random-network structure model, is very similar to that of vitreous silica, consisting mainly of SiO 4- 4 tetrahedra interconnected by bridging O atoms with additional local disorder generated by the replacement, on average, of one in ten Si atoms by aluminium. (orig.)

  2. High pressure neutron powder diffraction at LANSCE

    International Nuclear Information System (INIS)

    Von Dreele, R.B.

    1994-01-01

    By making use of the recently developed ''Paris-Edinburgh'' high pressure cell, the author has successfully performed neutron powder experiments to 10GPa at ambient temperature. Results for the structural compression of the high Tc 1223-Hg superconductor to 9.2 GPa, the compression and possible hydrogen bond formation in brucite, Mg(OD) 2 , to 9.3 GPa, and the molecular reorientation in nitromethane to 5.5 GPa will be presented

  3. Maximizing Macromolecule Crystal Size for Neutron Diffraction Experiments

    Science.gov (United States)

    Judge, R. A.; Kephart, R.; Leardi, R.; Myles, D. A.; Snell, E. H.; vanderWoerd, M.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    A challenge in neutron diffraction experiments is growing large (greater than 1 cu mm) macromolecule crystals. In taking up this challenge we have used statistical experiment design techniques to quickly identify crystallization conditions under which the largest crystals grow. These techniques provide the maximum information for minimal experimental effort, allowing optimal screening of crystallization variables in a simple experimental matrix, using the minimum amount of sample. Analysis of the results quickly tells the investigator what conditions are the most important for the crystallization. These can then be used to maximize the crystallization results in terms of reducing crystal numbers and providing large crystals of suitable habit. We have used these techniques to grow large crystals of Glucose isomerase. Glucose isomerase is an industrial enzyme used extensively in the food industry for the conversion of glucose to fructose. The aim of this study is the elucidation of the enzymatic mechanism at the molecular level. The accurate determination of hydrogen positions, which is critical for this, is a requirement that neutron diffraction is uniquely suited for. Preliminary neutron diffraction experiments with these crystals conducted at the Institute Laue-Langevin (Grenoble, France) reveal diffraction to beyond 2.5 angstrom. Macromolecular crystal growth is a process involving many parameters, and statistical experimental design is naturally suited to this field. These techniques are sample independent and provide an experimental strategy to maximize crystal volume and habit for neutron diffraction studies.

  4. Dynamic theory of neutron diffraction from a moving grating

    Energy Technology Data Exchange (ETDEWEB)

    Bushuev, V. A., E-mail: vabushuev@yandex.ru [Moscow State University (Russian Federation); Frank, A. I.; Kulin, G. V. [Joint Institute for Nuclear Research (Russian Federation)

    2016-01-15

    A multiwave dynamic theory of diffraction of ultracold neutrons from a moving phase grating has been developed in the approximation of coupled slowly varying amplitudes of wavefunctions. The effect of the velocity, period, and height of grooves of the grating, as well as the spectral angular distribution of the intensity of incident neurons, on the discrete energy spectrum and the intensity of diffraction reflections of various orders has been analyzed.

  5. Neutron thermalization in light water

    International Nuclear Information System (INIS)

    Abbate, M.J.; Lolich, J.V.

    1975-05-01

    Investigations related to neutron thermalization in light water have been made. Neutron spectra under quasi-infinite-medium conditions have been measured by the time-of-flight technique and calculations were performed with different codes. Through the use of improved experimental techniques and the best known calculational techniques available, the known discrepancies between experimentals and theoretical values were below from 40% to 16%. The present disagreement is believed to be due the scattering model used (ENDF-GASKET, based on the modified Haywood II frequency spectra), that shows to be very satisfactory for poisoned light water cases. Moreover, previous experiments were completed and differential, integral and pulse-source experimental techniques were improved. Also a second step of a neutron and reactor calculation system was completed. (author)

  6. In-situ neutron diffraction characterization of temperature dependence deformation in α-uranium

    Science.gov (United States)

    Calhoun, C. A.; Garlea, E.; Sisneros, T. A.; Agnew, S. R.

    2018-04-01

    In-situ strain neutron diffraction measurements were conducted at temperature on specimens coming from a clock-rolled α-uranium plate, and Elasto-Plastic Self-Consistent (EPSC) modeling was employed to interpret the findings. The modeling revealed that the active slip systems exhibit a thermally activated response, while deformation twinning remains athermal over the temperature ranges explored (25-150 °C). The modeling also allowed assessment of the effects of thermal residual stresses on the mechanical response during compression. These results are consistent with those from a prior study of room-temperature deformation, indicating that the thermal residual stresses strongly influence the internal strain evolution of grain families, as monitored with neutron diffraction, even though accounting for these residual stresses has little effect on the macroscopic flow curve, except in the elasto-plastic transition.

  7. 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

  8. Preferred orientations in niobium determined by neutrons diffraction

    International Nuclear Information System (INIS)

    Ueno, S.I.N.

    1979-01-01

    Neutron diffraction has been utilized to study textures developed in polycrystalline niobium, cold rolled to 60%, 80% and 95% in tickness and cold rolled to 95% in thickness and annealed at 800 0 C for 15, 30, 60 and 120 minutes in a vacuum of 10 -4 TORR [pt

  9. Neutron diffraction studies of high-T/sub c/ superconductors

    International Nuclear Information System (INIS)

    Jorgensen, J.D.

    1988-03-01

    Neutron powder diffraction techniques have been used extensively for the study of high-T/sub c/ oxide superconductors because of the need to locate oxygen atoms and accurately determine the oxygen site occupancies, and the difficulty in obtaining single crystals. For example, in the case of YBa 2 Cu 3 O/sub 7-δ/, neutron powder diffraction and Rietveld structural refinement were used to obtain the first complete structural information. Subsequent experiments focussed on determining the relationship of superconducting properties to the number and distribution of oxygen vacancies on the Cu-O sublattice with measurements being done on samples in thermodynamic equilibrium, at high temperature in controlled oxygen atmospheres, and on metastable, oxygen-deficient samples produced by quenching. Neutron powder diffraction has also been used to determine the structures of compounds in which the properties have been modified by substitution on the Y, Ba, or Cu sites. This paper briefly reviews some of the neutron powder diffraction results in these areas. 17 refs

  10. Physics and chemistry of materials from neutron diffraction and spectroscopy

    International Nuclear Information System (INIS)

    Dahlborg, U.; Lovesey, S.W.; Uppsala Univ.

    1990-11-01

    A short introduction to the powerful techniques of neutron diffraction and spectroscopy is illustrated largely with achievements by Swedish researchers in the past few years. Background material on sources and instrumentation is included, together with a directory of facilities routinely available to the Swedish scientific community. (author)

  11. Neutron diffraction on a large block mosaic crystal

    International Nuclear Information System (INIS)

    Kim Chir Sen; Nitts, V.V.

    1985-01-01

    The neutron diffraction by the mosaic single crystal with size of crystallites sufficient to achieve the primary extinction saturation is considered. Two cases where the proportionality between the reflection intensity and the structure amplitude is performed are analysed. Such a dependence is convenient for structure investigations. The difficulties connected with the accounting of the extinction are eliminated considerably

  12. Investigation of Methacrylic Acid at High Pressure Using Neutron Diffraction

    DEFF Research Database (Denmark)

    Marshall, William G.; Urquhart, Andrew; Oswald, Iain D. H.

    2015-01-01

    This article shows that pressure can be a low-intensity route to the synthesis of polymethacrylic acid. The exploration of perdeuterated methacrylic acid at high pressure using neutron diffraction reveals that methacrylic acid exhibits two polymorphic phase transformations at relatively low...

  13. Lattice strain measurements on sandstones under load using neutron diffraction

    Science.gov (United States)

    Frischbutter, A.; Neov, D.; Scheffzük, Ch.; Vrána, M.; Walther, K.

    2000-11-01

    Neutron diffraction methods (both time-of-flight- and angle-dispersive diffraction) are applied to intracrystalline strain measurements on geological samples undergoing uniaxial increasing compressional load. The experiments were carried out on Cretaceous sandstones from the Elbezone (East Germany), consisting of >95% quartz which are bedded but without crystallographic preferred orientation of quartz. From the stress-strain relation the Young's modulus for our quartz sample was determined to be (72.2±2.9) GPa using results of the neutron time-of-flight method. The influence of different kinds of bedding in sandstones (laminated and convolute bedding) could be determined. We observed differences of factor 2 (convolute bedding) and 3 (laminated bedding) for the elastic stiffness, determined with angle dispersive neutron diffraction (crystallographic strain) and with strain gauges (mechanical strain). The data indicate which geological conditions may influence the stress-strain behaviour of geological materials. The influence of bedding on the stress-strain behaviour of a laminated bedded sandstone was indicated by direct residual stress measurements using neutron time-of-flight diffraction. The measurements were carried out six days after unloading the sample. Residual strain was measured for three positions from the centre to the periphery and within two radial directions of the cylinder. We observed that residual strain changes from extension to compression in a different manner for two perpendicular directions of the bedding plane.

  14. Neutron Diffraction Investigation of MnAs under High Pressure

    DEFF Research Database (Denmark)

    Andresen, A.F; Fjellvag, H; Lebech, Bente

    1984-01-01

    Powdered MnAs has been investigated by neutron diffraction in a pressure cryostat, at hydrostatic pressures up to 13 kbar and temperatures down to 4.2 K. It has been found that in the orthorhombic MnP type structure, which under pressure is retained at low temperature, a spiral magnetic structure...

  15. Neutron diffraction experiments on ordered silver nuclei at Picokelvin temperatures

    International Nuclear Information System (INIS)

    Annila, A.J.; Hakonen, P.J.; Lounasmaa, O.V.; Nummila, K.K.; Oja, A.S.; Tuoriniemi, J.T.; Clausen, K.N.; Lindgaard, P.-A.; Siemensmeyer, K.; Steiner, M.; Weinfurter, H.; Viertioe, H.E.

    1990-08-01

    Nuclear spins in silver constitute an ideal antiferromagnetic spin - 1/2 model system in an fcc lattice. The nuclei are well localized and the interactions coupling the spins can be calculated from first principles. Strong quantum effects are expected owing to spin - 1/2. The magnetic phase diagram of the system has been investigated by several theoretical methods. In the present study the feasibility of neutron diffraction experiments on nuclear magnetic order in silver is discussed. The requirements for cryogenics and for neutron equipment are based on experience with current NMR measurements on sivler and with neutron diffraction work on copper. It is concluded that an experiment using an isotopically enriched specimen of either 107 Ag or 109 Ag is feasible but difficult. (author) 1 tab., 16 ills., 38 refs

  16. Neutron powder diffraction under high pressure at J-PARC

    International Nuclear Information System (INIS)

    Utsumi, Wataru; Kagi, Hiroyuki; Komatsu, Kazuki; Arima, Hiroshi; Nagai, Takaya; Okuchi, Takuo; Kamiyama, Takashi; Uwatoko, Yoshiya; Matsubayashi, Kazuyuki; Yagi, Takehiko

    2009-01-01

    It is expected that high-pressure material science and the investigation of the Earth's interior will progress greatly using the high-flux pulse neutrons of J-PARC. In this article, we introduce our plans for in situ neutron powder diffraction experiments under high pressure at J-PARC. The use of three different types of high-pressure devices is planned; a Paris-Edinburgh cell, a new opposed-anvil cell with a nano-polycrystalline diamond, and a cubic anvil high-pressure apparatus. These devices will be brought to the neutron powder diffraction beamlines to conduct a 'day-one' high-pressure experiment. For the next stage of research, we propose construction of a dedicated beamline for high-pressure material science. Its conceptual designs are also introduced here.

  17. Quantitative multiphase analysis of archaeological bronzes by neutron diffraction

    CERN Document Server

    Siano, S; Celli, M; Pini, R; Salimbeni, R; Zoppi, M; Kockelmann, W A; Iozzo, M; Miccio, M; Moze, O

    2002-01-01

    In this paper, we report the first investigation on the potentials of neutron diffraction to characterize archaeological bronze artifacts. The preliminary feasibility of phase and structural analysis was demonstrated on standardised specimens with a typical bronze alloy composition. These were realised through different hardening and annealing cycles, simulating possible ancient working techniques. The Bragg peak widths that resulted were strictly dependent on the working treatment, thus providing an important analytical element to investigate ancient making techniques. The diagnostic criteria developed on the standardised specimens were then applied to study two Etruscan museum pieces. Quantitative multiphase analysis by Rietveld refinement of the diffraction patterns was successfully demonstrated. Furthermore, the analysis of patterns associated with different artifact elements also yielded evidence for some peculiar perspective of the neutron diffraction diagnostics in archeometric applications. (orig.)

  18. Hyper-thermal neutron irradiation field for neutron capture therapy

    International Nuclear Information System (INIS)

    Sakurai, Yoshinori; Kobayashi, Tooru; Kanda, Keiji

    1994-01-01

    The utilization of hyper-thermal neutrons, which have an energy spectrum of a Maxwell distribution higher than the room temperature of 300 K, has been studied in order to improve the thermal neutron flux distribution in a living body for a deep-seated tumor in neutron capture therapy (NCT). Simulation calculations using MCNP-V3 were carried out in order to investigate the characteristics of the hyper-thermal neutron irradiation field. From the results of simulation calculations, the following were confirmed: (i) The irradiation field of the hyper-thermal neutrons is feasible by using some scattering materials with high temperature, such as Be, BeO, C, SiC and ZrH 1.7 . Especially, ZrH 1.7 is thought to be the best material because of good characteristics of up-scattering for thermal neutrons. (ii) The ZrH 1.7 of 1200 K yields the hyper-thermal neutrons of a Maxwell-like distribution at about 2000 K and the treatable depth is about 1.5 cm larger comparing with the irradiation of the thermal neutrons of 300 K. (iii) The contamination by the secondary gamma-rays from the scattering materials can be sufficiently eliminated to the tolerance level for NCT through the bismuth layer, without the larger change of the energy spectrum of hyper-thermal neutrons. ((orig.))

  19. High precision thermal neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Radeka, V.; Schaknowski, N.A.; Smith, G.C.; Yu, B. [Brookhaven National Laboratory, Upton, NY (United States)

    1994-12-31

    Two-dimensional position sensitive detectors are indispensable in neutron diffraction experiments for determination of molecular and crystal structures in biology, solid-state physics and polymer chemistry. Some performance characteristics of these detectors are elementary and obvious, such as the position resolution, number of resolution elements, neutron detection efficiency, counting rate and sensitivity to gamma-ray background. High performance detectors are distinguished by more subtle characteristics such as the stability of the response (efficiency) versus position, stability of the recorded neutron positions, dynamic range, blooming or halo effects. While relatively few of them are needed around the world, these high performance devices are sophisticated and fairly complex, their development requires very specialized efforts. In this context, we describe here a program of detector development, based on {sup 3}He filled proportional chambers, which has been underway for some years at the Brookhaven National Laboratory. Fundamental approaches and practical considerations are outlined that have resulted in a series of high performance detectors with the best known position resolution, position stability, uniformity of response and reliability over time, for devices of this type.

  20. Steel research using neutron beam techniques. In-situ neutron diffraction, small-angle neutron scattering and residual stress analysis

    International Nuclear Information System (INIS)

    Sueyoshi, Hitoshi; Ishikawa, Nobuyuki; Yamada, Katsumi; Sato, Kaoru; Nakagaito, Tatsuya; Matsuda, Hiroshi; Arakaki, Yu; Tomota, Yo

    2014-01-01

    Recently, the neutron beam techniques have been applied for steel researches and industrial applications. In particular, the neutron diffraction is a powerful non-destructive method that can analyze phase transformation and residual stress inside the steel. The small-angle neutron scattering is also an effective method for the quantitative evaluation of microstructures inside the steel. In this study, in-situ neutron diffraction measurements during tensile test and heat treatment were conducted in order to investigate the deformation and transformation behaviors of TRIP steels. The small-angle neutron scattering measurements of TRIP steels were also conducted. Then, the neutron diffraction analysis was conducted on the high strength steel weld joint in order to investigate the effect of the residual stress distribution on the weld cracking. (author)

  1. Study of the ferrimagnetic and paramagnetic phases of magnetite measured by multiple neutron diffraction

    International Nuclear Information System (INIS)

    Mazzocchi, V.L.

    1992-01-01

    Structural parameters of the ferrimagnetic and paramagnetic phases of magnetite have been refined from neutron multiple diffraction data. Experimental multiple diffraction patterns used in the refinement, were obtained by measuring the 111 primary reflection of a natural single crystal of this compound, at room temperature for the ferrimagnetic phase and 703 0 C for the paramagnetic phase. Corresponding theoretical patterns for both phases have been calculated by the program MULTI which uses the iterative method for the intensity calculations in neutron multiple diffraction. In this method intensities are calculated as Taylor series expansions summed up to a order sufficient for a good approximation. A step by step process has been used in the refinements according to the parameter-shift method. Both isotropic and anisotropic thermal parameters were used in the calculation of the temperature factor. (author)

  2. Fabrication of vanadium cans for neutron diffraction experiments

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chin man; Baik, Sung Hoon; Park, Sun Kyu

    1999-12-01

    The laser weld technique of vanadium developed to experiment for neutron diffraction of HANARO. The demands for this laser welding technique were applied to process control in vanadium film welding and to fabricate various sizing vanadium cans. The vanadium can had a advantage to have less coherent in neutron. KAERI developed the fabrication jig of 6-12 mm diameter cans using 0.125 mm vanadium thin film, and investigated the laser welding procedure for making the various diameter and length of vanadium cans using the fabricated jigs and Nd:YAG laser. (author)

  3. High-resolution neutron-diffraction measurements to 8 kbar

    Science.gov (United States)

    Bull, C. L.; Fortes, A. D.; Ridley, C. J.; Wood, I. G.; Dobson, D. P.; Funnell, N. P.; Gibbs, A. S.; Goodway, C. M.; Sadykov, R.; Knight, K. S.

    2017-10-01

    We describe the capability to measure high-resolution neutron powder diffraction data to a pressure of at least 8 kbar. We have used the HRPD instrument at the ISIS neutron source and a piston-cylinder design of pressure cell machined from a null-scattering titanium zirconium alloy. Data were collected under hydrostatic conditions from an elpasolite perovskite La?NiMnO?; by virtue of a thinner cell wall on the incident-beam side of the cell, it was possible to obtain data in the instrument's highest resolution back-scattering detector banks up to a maximum pressure of 8.5 kbar.

  4. Structure of amorphous selenium studied by neutron diffraction

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Knudsen, Torben Steen; Carneiro, K.

    1975-01-01

    Neutron diffraction measurements on amorphous selenium have been performed at 293 and 80 K. Careful analyses of the instrumental corrections were made to avoid systematic errors in the measured structure factor S (kappa) in the wave vector region 0 ? kappa ? 12 Å−1. As a result of the data...... treatment, the neutron scattering cross sections of selenium are determined to be sigmacoh = 8.4±0.1 b and sigmainc = 0.1±0.1 b. Using the fact that S (kappa) for large kappa's is determined by the short distances in the sample, a new method for extrapolation of the experimental S (kappa) until convergence....... Finally, we give a brief discussion of the different models for the structure of amorphous selenium, taking both diffraction measurements and thermodynamic considerations into account. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

  5. Neutron diffraction by monocrystals of inorganic and elementary organic compounds

    International Nuclear Information System (INIS)

    Becker, G.; Hauser, H.D.

    1992-01-01

    The phase of preparation and X-ray structural analysis of the compounds has been completed following the synthetical preparation of compounds sensitive to oxidation and pyrolysis, in this case: phosphonic acid, potassium silanide, lithium dihydrogenphosphide * DME, bis[lithium-tri(tert.butyl)alanate], dibromophenylbismuthate, potassium tetrahydride aluminate, and phosphinic acid. The work was started is neutron diffraction experiments for detecting the positions of the hydrogen and carbon atoms, in order to analyse space group problems. (BBR) [de

  6. Neutron diffraction study of α-iron titanium cerium hydride

    International Nuclear Information System (INIS)

    Lin Hong; Niu Shiwen; Gou Cheng

    1987-01-01

    The results of the neutron scattering method shows that the crystal structure of Fe 0.94 TiCe 0.06 H 0.03 is the same as that of the FeTiH 0.02 . However, its diffraction peak intensities drop by 47-58%, the background increased markedly about 2 times and the lattice constant increase by 5%

  7. Practical conditions in the neutron diffraction under high pressure

    International Nuclear Information System (INIS)

    Kamigaki, Kazuo; Ohashi, Masayoshi

    1993-01-01

    Practical analysis is made on some conditions in utilizing neutrons for the study of atomistic structure of materials under high pressure. Investigation is made on the geometrical conditions; size of the specimen, width of slits, and the rate of extra-scattering. Experiments are performed on the effects of absorption by high pressure cell and the disturbance due to an overlapping of diffraction peaks. An observation is presented on the pressure-induced transformation in RbBr. (author)

  8. Neutron diffraction utilizing the T-O-F method

    Energy Technology Data Exchange (ETDEWEB)

    Niimura, N [Tohoku Univ., Sendai (Japan). Lab. of Nuclear Science

    1974-12-01

    Characteristic features of the TOF (time of flight) neutron diffraction are summarized. In this method, i) all the reciprocal points on the rod passing through the origin in the reciprocal space can be scanned by each burst of white neutrons, ii) it is easy to measure high index reflections at the large scattering angle, iii) each reflection is not affected by the higher-order harmonics, and iv) it is easy to measure the physical properties depending on the neutron wavelength. The pulse neutron generator as well as the data acquisition system in the Laboratory of Nuclear Science of Tohoku University is described. The TOF method seems to be very powerful if it is applied to accurate structure analysis. The data correction methods are discussed. The TOF method is prospective to the study of transient phenomena. In this method one can apply to the crystalline sample an external field pulsed with the same frequency as the neutrons. By using this method, the transient state of the polarization reversal of the ferroelectric NaNO/sub 2/ has been observed. The magnetically pulsed neutron TOF spectrometer is briefly introduced after a review of the chopper history.

  9. Residual stress measurements by means of neutron diffraction

    International Nuclear Information System (INIS)

    Pintschovius, L.; Jung, V.; Macherauch, E.; Voehringer, O.

    1983-01-01

    A new method for the analysis of multiaxial residual stress states is presented, which is based on high resolution neutron diffraction. It is analogous to X-ray stress analysis, but the use of neutrons instead of X-rays allows the analysis of the stress distributions also in the interior of technical components in a non-destructive way. To prove the feasibility of the method, investigations of the loading stress distributions of an aluminium bar subjected to purely elastic bending were performed. Limiting factors due to the volume of the internal probe region and the sample thickness are discussed. Complete neutron residual stress analyses were carried out for a plastically deformed bending bar and a transformation-free water-quenched steel cylinder. The results are in fairly good agreement with theoretical expectations and with X-ray control measurements at the surface of the objects. (Auth.)

  10. Engineering related neutron diffraction measurements probing strains, texture and microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, Bjorn [Los Alamos National Laboratory; Brown, Donald W [Los Alamos National Laboratory; Tome, Carlos N [Los Alamos National Laboratory; Balogh, Levente [Los Alamos National Laboratory; Vogel, Sven C [Los Alamos National Laboratory

    2010-01-01

    Neutron diffraction has been used for engineering applications for nearly three decades. The basis of the technique is powder diffraction following Bragg's Law. From the measured diffraction patterns information about internal, or residual, strain can be deduced from the peak positions, texture information can be extracted from the peak intensities, and finally the peak widths can provide information about the microstructure, e.g. dislocation densities and grain sizes. The strains are measured directly from changes in lattice parameters, however, in many cases it is non-trivial to determine macroscopic values of stress or strain from the measured data. The effects of intergranular strains must be considered, and combining the neutron diffraction measurements with polycrystal deformation modeling has proven invaluable in determining the overall stress and strain values of interest in designing and dimensioning engineering components. Furthelmore, the combined use of measurements and modeling has provided a tool for elucidating basic material properties, such as critical resolved shear stresses for the active deformation modes and their evolution as a function of applied deformation.

  11. Profile analysis of neutron powder diffraction data at ISIS

    International Nuclear Information System (INIS)

    David, W.I.F.; Ibberson, R.M.; Matthewman, J.C.

    1992-05-01

    The aim of this manual is to document the current suite of time-of-flight neutron powder diffraction profile refinement programs available to ISIS users. Aspects of data collation and normalisation specific to the individual diffraction instruments are dealt with elsewhere. It will be assumed the user has produced a suitable data file (.DAT file) containing the profile data consisting of point by point values of the corrected diffraction profile across the pattern. The analysis of neutron powder diffraction data at ISIS by profile refinement utilises a suite of ''in-house'' written and supported programs based on the Cambridge Crystallography Subroutine Library (CCSL). A quick scan through the CCSL manual will give the user a general feel for the procedure to adopt in the use of the library and hence of the profile codes. The instructions documented in this handbook are complementary to those in the more specialist CCSL manual, and consequently go into no great detail regarding technical details of any of the CCSL routines. The programs may be run from each individual user account, for example [USER01], once the appropriate login procedure has been set-up by the instrument scientists. The programs are mostly activated by one line commands and only a basic knowledge of a VAX editor should be required; details can be found in the ''VAX primer'' available from Computer Support. (Author)

  12. Thermal neutron shield and method of manufacture

    Science.gov (United States)

    Brindza, Paul Daniel; Metzger, Bert Clayton

    2013-05-28

    A thermal neutron shield comprising concrete with a high percentage of the element Boron. The concrete is least 54% Boron by weight which maximizes the effectiveness of the shielding against thermal neutrons. The accompanying method discloses the manufacture of Boron loaded concrete which includes enriching the concrete mixture with varying grit sizes of Boron Carbide.

  13. Pulsed thermal neutron source at the fast neutron generator.

    Science.gov (United States)

    Tracz, Grzegorz; Drozdowicz, Krzysztof; Gabańska, Barbara; Krynicka, Ewa

    2009-06-01

    A small pulsed thermal neutron source has been designed based on results of the MCNP simulations of the thermalization of 14 MeV neutrons in a cluster-moderator which consists of small moderating cells decoupled by an absorber. Optimum dimensions of the single cell and of the whole cluster have been selected, considering the thermal neutron intensity and the short decay time of the thermal neutron flux. The source has been built and the test experiments have been performed. To ensure the response is not due to the choice of target for the experiments, calculations have been done to demonstrate the response is valid regardless of the thermalization properties of the target.

  14. Fourier diffraction theorem for diffusion-based thermal tomography

    International Nuclear Information System (INIS)

    Baddour, Natalie

    2006-01-01

    There has been much recent interest in thermal imaging as a method of non-destructive testing and for non-invasive medical imaging. The basic idea of applying heat or cold to an area and observing the resulting temperature change with an infrared camera has led to the development of rapid and relatively inexpensive inspection systems. However, the main drawback to date has been that such an approach provides mainly qualitative results. In order to advance the quantitative results that are possible via thermal imaging, there is interest in applying techniques and algorithms from conventional tomography. Many tomography algorithms are based on the Fourier diffraction theorem, which is inapplicable to thermal imaging without suitable modification to account for the attenuative nature of thermal waves. In this paper, the Fourier diffraction theorem for thermal tomography is derived and discussed. The intent is for this thermal-diffusion based Fourier diffraction theorem to form the basis of tomographic reconstruction algorithms for quantitative thermal imaging

  15. Neutron diffraction tomography: a unique, 3D inspection technique for crystals using an intensifier TV system

    International Nuclear Information System (INIS)

    Davidson, J.B.; Case, A.L.

    1978-01-01

    The application of phosphor-intensifier-TV techniques to neutron topography and tomography of crystals is described. The older, analogous x-ray topography using wavelengths approximately 1.5A is widely used for surface inspection. However, the crystal must actually be cut in order to see diffraction anomalies beneath the surface. Because 1.5-A thermal neutrons are highly penetrating, much larger and thicker specimens can be used. Also, since neutrons have magnetic moments, they are diffracted by magnetic structures within crystals. In neutron volume topography, the entire crystal or a large part of it is irradiated, and the images obtained are superimposed reflections from the total volume. In neutron tomography (or section topography), a collimated beam irradiates a slice (0.5 to 10 mm) of the crystal. The diffracted image is a tomogram from this part only. A series of tomograms covering the crystal can be taken as the specimen is translated in steps across the narrow beam. Grains, voids, twinning, and other defects from regions down to 1 mm in size can be observed and isolated. Although at present poorer in resolution than the original neutron and film methods, the TV techniques are much faster and, in some cases, permit real-time viewing. Two camera systems are described: a counting camera having a 150 mm 6 Li-ZnS screen for low-intensity reflections which are integrated in a digital memory, and a 300-mm system using analog image storage. Topographs and tomograms of several crystals ranging in size from 4 mm to 80 mm are shown

  16. Levitation apparatus for neutron diffraction investigations on high temperature liquids

    International Nuclear Information System (INIS)

    Hennet, Louis; Pozdnyakova, Irina; Bytchkov, Aleksei; Cristiglio, Viviana; Palleau, Pierre; Fischer, Henry E.; Cuello, Gabriel J.; Johnson, Mark; Melin, Philippe; Zanghi, Didier; Brassamin, Severine; Brun, Jean-Francois; Price, David L.; Saboungi, Marie-Louise

    2006-01-01

    We describe a new high temperature environment based on aerodynamic levitation and laser heating designed for neutron scattering experiments up to 3000 deg. C. The sample is heated to the desired temperature with three CO 2 lasers from different directions in order to obtain a homogeneous temperature distribution. The apparent temperature of the sample is measured with an optical pyrometer, and two video cameras are employed to monitor the sample behavior during heating. The levitation setup is enclosed in a vacuum-tight chamber, enabling a high degree of gas purity and a reproducible sample environment for structural investigations on both oxide and metallic melts. High-quality neutron diffraction data have been obtained on liquid Y 3 Al 5 O 12 and ZrNi alloy for relatively short counting times (1.5 h)

  17. Magnetic neutron diffraction of MnO thin films

    International Nuclear Information System (INIS)

    Neubeck, W.; Vettier, C.; Mannix, D.; Bernhoeft, N.; Hiess, A.; Ranno, L.; Givord, D.

    1999-01-01

    We report on magnetic neutron diffraction carried out on various epitaxial MnO(III) thin films grown on sapphire and MgO substrates. In all samples, of masses between 5 and 50 μg, magnetic Bragg peaks have been observed. The films exhibit what appears to be continuous phase-transitions in contrast to the strongly discontinuous transition exhibited by bulk samples. In addition, the Neel temperature of films prepared on sapphire substrates is strongly enhanced above that of the bulk whilst that of the film grown on MgO is depressed. The possibility to measure magnetic excitations in such thin film systems is discussed in the light of promising test results obtained from an inelastic magnetic neutron scattering experiment on the IN8 spectrometer. (authors)

  18. Residual stress measurement in socket welded joints by neutron diffraction

    International Nuclear Information System (INIS)

    Hayashi, Makoto; Ishiwata, Masayuki; Minakawa, Noriaki; Funahashi, Satoru.

    1995-01-01

    Neutron diffraction measurements of lattice spacings provide the spatial map of residual stress near welds in ferritic steel socket joints. The high tensile stress greater than 200 MPa was found in the fusion and heat-affected zones in the hoop direction. However, the highest tensile stress in the axial direction at the weld root was about 110 MPa relatively lower than the expected value from the fatigue test results. The balancing compressive stress was found near the surface of the socket weld fusion zone. Heat treatment at 625degC for 2 hours was sufficient for the relief of residual stress in socket welds. (author)

  19. Membrane structure: neutron diffraction and small angle scattering studies

    International Nuclear Information System (INIS)

    Zaccai, G.

    1985-01-01

    The author considers a molecule in a beam of radiation of wavelength lambda. Two extreme ways are shown in which on can have many identical molecules in a sample: a crystal in which they are related to each other by the symmetry of a lattice, and complete disorder in which there is no correlation between molecules. The detailed crystallographic analysis of isomorphous replacement is examined. Neutron diffraction experiments with specific deuteration are performed to characterize interactions of cholesterol with lipid bilayers. Retinal rod outer segment disk membranes and the purple membrane of H. halobium are examined

  20. Attenuation of thermal neutron through graphite

    International Nuclear Information System (INIS)

    Adib, M.; Ismaail, H.; Fathaallah, M.; Abbas, Y.; Habib, N.; Wahba, M.

    2004-01-01

    Calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of graphite temperature and crystalline from for neutron energies from 1 me V< E<10 eV were carried out. Computer programs have been developed which allow calculation for the graphite hexagonal closed-pack structure in its polycrystalline form and pyrolytic one. I The calculated total cross-section for polycrystalline graphite were compared with the experimental values. An overall agreement is indicated between the calculated values and experimental ones. Agreement was also obtained for neutron cross-section measured for oriented pyrolytic graphite at room and liquid nitrogen temperatures. A feasibility study for use of graphite in powdered form as a cold neutron filter is details. The calculated attenuation of thermal neutrons through large mosaic pyrolytic graphite show that such crystals can be used effectively as second order filter of thermal neutron beams and that cooling improve their effectiveness

  1. Applications of image plates in neutron radiography and neutron diffraction at BARC, Trombay

    International Nuclear Information System (INIS)

    Shaikh, A.M.

    2013-01-01

    Neutron radiography techniques based on Gd, Dy and In metallic foils and X-ray film have been used at this centre since early seventies for various NDT and R and D work in nuclear, defence and aerospace industries. In recent years use of photostimulated luminescence based phosphor imaging plate has been introduced in our work. This has enabled to achieve higher sensitivities and dynamic ranges of recording radiographs with acceptable spatial resolution. It also provides digital image information which is more convenient for quantitative evaluations. Neutron image plates have been used in variety of radiography techniques such as conventional neutron radiography (NR), neutron induced beta radiography (NIBR), hydrogen sensitive epithermal neutron radiography (HYSEN) and for neutron powder diffractometry using Apsara, CIRUS and Dhruva reactors as neutron sources. Recently the image plates have also been used for characterization of thermalized neutron beam from a plasma focus neutron source and recording neutron radiographs. Prior to the utilization image plates have been characterised for their performance. Details of the measurements and applications will be presented. (author)

  2. Neutron diffraction measurements at the INES diffractometer using a neutron radiative capture based counting technique

    Energy Technology Data Exchange (ETDEWEB)

    Festa, G. [Centro NAST, Universita degli Studi di Roma Tor Vergata, Roma (Italy); Pietropaolo, A., E-mail: antonino.pietropaolo@roma2.infn.it [Centro NAST, Universita degli Studi di Roma Tor Vergata, Roma (Italy); Grazzi, F.; Barzagli, E. [CNR-ISC Firenze (Italy); Scherillo, A. [CNR-ISC Firenze (Italy); ISIS facility Rutherford Appleton Laboratory (United Kingdom); Schooneveld, E.M. [ISIS facility Rutherford Appleton Laboratory (United Kingdom)

    2011-10-21

    The global shortage of {sup 3}He gas is an issue to be addressed in neutron detection. In the context of the research and development activity related to the replacement of {sup 3}He for neutron counting systems, neutron diffraction measurements performed on the INES beam line at the ISIS pulsed spallation neutron source are presented. For these measurements two different neutron counting devices have been used: a 20 bar pressure squashed {sup 3}He tube and a Yttrium-Aluminum-Perovskite scintillation detector. The scintillation detector was coupled to a cadmium sheet that registers the prompt radiative capture gamma rays generated by the (n,{gamma}) nuclear reactions occurring in cadmium. The assessment of the scintillator based counting system was done by performing a Rietveld refinement analysis on the diffraction pattern from an ancient Japanese blade and comparing the results with those obtained by a {sup 3}He tube placed at the same angular position. The results obtained demonstrate the considerable potential of the proposed counting approach based on the radiative capture gamma rays at spallation neutron sources.

  3. Deformation processes in functional materials studied by in situ neutron diffraction and ultrasonic techniques

    International Nuclear Information System (INIS)

    Sittner, P.; Novak, V.; Landa, M.; Lukas, P.

    2007-01-01

    The unique thermomechanical functions of shape memory alloys (hysteretic stress-strain-temperature responses) not their structural properties (as strength, fatigue, corrosion resistance, etc.) are primarily utilized in engineering applications. In order to better understand and predict the functional behavior, we have recently employed two dedicated non-invasive in situ experimental methods capable to follow the deformation/transformation processes in thermomechanically loaded polycrystalline samples. The in situ neutron diffraction method takes advantage of the ability of thermal neutrons to penetrate bulk samples. As a diffraction technique sensitive to interplanar spacings in crystalline solids, it provides in situ information on the changes in crystal structure, phase composition, phase stress and texture in the transforming samples. The combined in situ ultrasonic and electric resistance method follows variations of the electric resistance as well as speed and attenuation of acoustic waves propagating through the transforming sample. The acoustic waves are mainly sensitive to changes of elastic properties accompanying the deformation/transformation processes. The latter method thus follows the changes in interatomic bonds rather than changes in the interplanar lattice spacings focused in the neutron diffraction method. The methods are thus complementary. They are briefly described and selected experimental results obtained recently on NiTi alloys are presented and discussed

  4. Precise structural analysis of methane hydrate by neutron diffraction

    International Nuclear Information System (INIS)

    Igawa, Naoki; Hoshikawa, Akinori; Ishii, Yoshinobu

    2006-01-01

    Methane hydrate has attracted great interest as an energy resource to replace natural gas since this material is deposited in the seafloor and the deposits are estimated to exceed those of natural gas. Understanding the physical proprieties, such as the temperature dependence of the crystal structure, helps to specify the optimum environmental temperature and pressure during drilling, transport, and storage of methane hydrate. Clathrate hydrates consisted of encaging atomic and/or molecular species as a guest and host water formed by a hydrogen bonding. Although many studies on the clathrate hydrate including methane hydrate were reported, no detailed crystallographic property has yet been cleared. We focused on the motion of methane in the clathrate hydrate by the neutron diffraction. The crystal structure of the methane hydrate was analyzed by the applying the combination of the Rietveld refinement and the maximum entropy method (MEM) to neutron powder diffraction. Temperature dependence of the scattering-length density distribution maps revealed that the motion of methane molecules differs between the shapes of dodecahedron and tetrakaidecahedron. (author)

  5. Neutron magnetic multiple diffraction in a natural magnetite crystal

    International Nuclear Information System (INIS)

    Mazzocchi, V.L.; Parente, C.B.R.

    1988-09-01

    Neutron multiple diffraction has been employed in the study of the magnetism in magnetite (Fe 3 O 4 ). Magnetite has a crystallographic structure of an inverted spinel with tetrahedral A sites occupied solely by trivalent Fe 3+ ions and octahedral B sites occupied both by divalent Fe 2+ ions and the remaining Fe 3+ ions in random distribution. At room temperature magnetite is a Neel A-B ferrimagnet where the ions on the A, B sites are coupled antiferromagneticaly. This coupling disappears at T sup c approx. or approx.= 580 0 C. Employing a natural single crystal of magnetite experimental neutron multiple diffraction patterns were obtained for the primary reflection 111 at room temperature and 703 0 C. This reflection is almost entirely magnetic in origin resulting in 'Aufhellung' patterns below T c and mixed 'Aufhellung-Umweganregung' patterns above T c . Theoretical patterns were calculated employing the iterative method for the approximation of intensities by a Taylor series and compared to the experimental results. (author) [pt

  6. Thermal neutron diffusion parameters in homogeneous mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Drozdowicz, K.; Krynicka, E. [Institute of Nuclear Physics, Cracow (Poland)

    1995-12-31

    A physical background is presented for a computer program which calculates the thermal neutron diffusion parameters for homogeneous mixtures of any compounds. The macroscopic absorption, scattering and transport cross section of the mixture are defined which are generally function of the incident neutron energy. The energy-averaged neutron parameters are available when these energy dependences and the thermal neutron energy distribution are assumed. Then the averaged diffusion coefficient and the pulsed thermal neutron parameters (the absorption rare and the diffusion constant) are also defined. The absorption cross section is described by the 1/v law and deviations from this behaviour are considered. The scattering cross section can be assumed as being almost constant in the thermal neutron region (which results from the free gas model). Serious deviations are observed for hydrogen atoms bound in molecules and a special study in the paper is devoted to this problem. A certain effective scattering cross section is found in this case on a base of individual exact data for a few hydrogenous media. Approximations assumed for the average cosine of the scattering angle are also discussed. The macroscopic parameters calculated are averaged over the Maxwellian energy distribution for the thermal neutron flux. An information on the input data for the computer program is included. (author). 10 refs, 4 figs, 5 tabs.

  7. Thermal neutron diffusion parameters in homogeneous mixtures

    International Nuclear Information System (INIS)

    Drozdowicz, K.; Krynicka, E.

    1995-01-01

    A physical background is presented for a computer program which calculates the thermal neutron diffusion parameters for homogeneous mixtures of any compounds. The macroscopic absorption, scattering and transport cross section of the mixture are defined which are generally function of the incident neutron energy. The energy-averaged neutron parameters are available when these energy dependences and the thermal neutron energy distribution are assumed. Then the averaged diffusion coefficient and the pulsed thermal neutron parameters (the absorption rare and the diffusion constant) are also defined. The absorption cross section is described by the 1/v law and deviations from this behaviour are considered. The scattering cross section can be assumed as being almost constant in the thermal neutron region (which results from the free gas model). Serious deviations are observed for hydrogen atoms bound in molecules and a special study in the paper is devoted to this problem. A certain effective scattering cross section is found in this case on a base of individual exact data for a few hydrogenous media. Approximations assumed for the average cosine of the scattering angle are also discussed. The macroscopic parameters calculated are averaged over the Maxwellian energy distribution for the thermal neutron flux. An information on the input data for the computer program is included. (author). 10 refs, 4 figs, 5 tabs

  8. Neutron diffraction instruments at the BR2 reactor and their use in the study of crystal and magnetic structures

    International Nuclear Information System (INIS)

    Legrand, E.

    1977-01-01

    The study of structural properties of condensed matted is frequently performed by means of methods based on X-ray, electron or neutron scattering. In many particular cases, the latter technique offers definite advantages which are mainly based on the following characteristics of neutron-matter interaction: The large penetration depth for neutrons in matter (with the exception of a few elements), which allow the study of large samples and the use of wavelengths from 0.5 to 5A, and even to 10 A; the absence of an atomic form factor; the irregular dependence of the scattering length for the different elements as a function of their atomic number; the large cross section for magnetic scattering; the energy of thermal neutrons which allows the direct measuremtment of the enrgy exchange between the neutrons and the scatterer. Three of the four neutron diffraction instruments for solid state research, installed at the BR2 reactor, are described in detail. (author)

  9. EL-2 reactor: Thermal neutron flux distribution

    International Nuclear Information System (INIS)

    Rousseau, A.; Genthon, J.P.

    1958-01-01

    The flux distribution of thermal neutrons in EL-2 reactor is studied. The reactor core and lattices are described as well as the experimental reactor facilities, in particular, the experimental channels and special facilities. The measurement shows that the thermal neutron flux increases in the central channel when enriched uranium is used in place of natural uranium. However the thermal neutron flux is not perturbed in the other reactor channels by the fuel modification. The macroscopic flux distribution is measured according the radial positioning of fuel rods. The longitudinal neutron flux distribution in a fuel rod is also measured and shows no difference between enriched and natural uranium fuel rods. In addition, measurements of the flux distribution have been effectuated for rods containing other material as steel or aluminium. The neutron flux distribution is also studied in all the experimental channels as well as in the thermal column. The determination of the distribution of the thermal neutron flux in all experimental facilities, the thermal column and the fuel channels has been made with a heavy water level of 1825 mm and is given for an operating power of 1000 kW. (M.P.)

  10. Single-crystal neutron diffraction study of ammonium nitrate phase III

    International Nuclear Information System (INIS)

    Choi, C.S.; Prask, H.J.

    1982-01-01

    The crystal structure of ammonium nitrate phase III has been studied at room temperature by neutron diffraction using a single crystal containing 5% KNO 3 in solid-solution form. The space group is Pnma, with a = 7.6772 (4), b = 5.8208 (4), c = 7.1396 (5) A, Z = 4. The final residual after full-matrix least-squares refinement was R = 0.042 for 348 observed reflections. The ammonium ions are thermally disordered into two orientations, displaced by an angle of approximately 42 0 about an axis parallel to the c axis. (Auth.)

  11. Magnetostructural transition in Fe5SiB2 observed with neutron diffraction

    Czech Academy of Sciences Publication Activity Database

    Cedervall, J.; Kontos, S.; Hansen, T. C.; Balmes, O.; Martinez-Casado, F. J.; Matěj, Z.; Beran, Přemysl; Svedlindh, P.; Gunnarsson, K.; Sahlberg, M.

    2016-01-01

    Roč. 235, MAR (2016), s. 113-118 ISSN 0022-4596 Institutional support: RVO:61389005 Keywords : magnetism * X-ray diffraction * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.299, year: 2016

  12. A new approach of quantum mechanics for neutron single-slit diffraction

    International Nuclear Information System (INIS)

    Wu Xiangyao; Yang Jinghai; Liu Xiaojing; Wang Li; Liu Bing; Fan Xihui; Guo Yiqing

    2007-01-01

    Phenomena of electron, neutron, atomic and molecular diffraction have been studied in many experiments, and these experiments are explained by many theoretical works. We study neutron single-slit diffraction with a quantum mechanical approach. It is found that the obvious diffraction patterns can be obtained when the single slit width a is in the range of 3λ-60λ. We also find a new quantum effect of the thickness of single-slit which can make a large impact on the diffraction pattern. The new quantum effect predicted in our work can be tested by the neutron single-slit diffraction experiment. (authors)

  13. Neutron diffraction study of TiCxNyHz

    International Nuclear Information System (INIS)

    Khidirov, I.

    1996-01-01

    Neutron diffraction study of titanium carbonitridohydride is carried out. It is shown that TiC x N y H z may have a disordered, on ordered and a partially ordered structure depending on the composition. Both in the ordered and in the disordered structure the atoms of carbon and nitrogen are located in octahedron interstices only. Under (C+N)/Ti > 0.70 the atoms of hydrogen are located in octahedron interstices only. Under (C+N)/Ti < 0.50 and under high temperatures the atoms of hydrogen occupy both octahedron and tetrahedron interstices; under low temperatures the transition of some hydrogen atoms from tetrahedron into octahedron interstices is observed. 15 refs.; 1 fig.; 1 tab

  14. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, J.P.; Gilchrist, P.J. [Univ. of Edinburgh (United Kingdom); Duff, K.C. [Univ. of Edinburgh Medical School (United Kingdom); Saxena, A.M. [Brookhaven National Laboratory, Upton, NY (United States)

    1994-12-31

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein.

  15. A neutron diffraction study of ancient Greek ceramics

    International Nuclear Information System (INIS)

    Siouris, I.M.; Walter, J.

    2006-01-01

    Non-destructive neutron diffraction studies were performed on three 2nd-century BC archaeological pottery fragments from the excavation site of Neos Scopos, Serres, in North Greece. In all the 273 K diagrams quartz and feldspars phase fractions are dominant. Diopside and iron oxide phases were also identifiable. The diopside content is found to decrease with increasing quartz-feldspar compositions. Iron oxides containing minerals were found to be present and the phase compositions reflect upon the coloring of the samples. However, the different content compositions of the phases may suggest different regions of the original clay materials as well as different preparation techniques. The firing temperatures were determined to be in the range of 900-1000 deg. C

  16. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    International Nuclear Information System (INIS)

    Bradshaw, J.P.; Gilchrist, P.J.; Duff, K.C.; Saxena, A.M.

    1994-01-01

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein

  17. Effect of loading mode on lattice strain measurements via neutron diffraction

    International Nuclear Information System (INIS)

    Skippon, T.; Clausen, B.; Daymond, M.R.

    2013-01-01

    The study of lattice strain evolution during uniaxial deformation via in situ neutron diffraction is a well established technique for characterizing the deformation behavior of metals. However, the relatively low flux of neutron facilities results in count times on the order of several minutes, requiring experimenters to choose between either applying a very slow strain rate, or loading the sample incrementally rather than continuously. Here we investigate the effects on lattice strain data obtained by using stress, strain, and position controlled incremental loading, as well as continuous loading, on samples of Zircaloy-2 under uniaxial compression. It was found that both qualitative and quantitative differences arise in the lattice strain behavior of certain grain families, particularly {101 ¯ 0} and {112 ¯ 0}, while other grain families show no discernible effect. The differences in lattice strain evolution brought on by the variation in loading modes are believed to be the result of thermally activated dislocation motion

  18. Attenuation of Thermal Neutrons by Crystalline Silicon

    International Nuclear Information System (INIS)

    Adib, M.; Habib, N.; Ashry, A.; Fathalla, M.

    2002-01-01

    A simple formula is given which allows to calculate the contribution of the total neutron cross - section including the Bragg scattering from different (hkt) planes to the neutron * transmission through a solid crystalline silicon. The formula takes into account the silicon form of poly or mono crystals and its parameters. A computer program DSIC was developed to provide the required calculations. The calculated values of the total neutron cross-section of perfect silicon crystal at room and liquid nitrogen temperatures were compared with the experimental ones. The obtained agreement shows that the simple formula fits the experimental data with sufficient accuracy .A good agreement was also obtained between the calculated and measured values of polycrystalline silicon in the energy range from 5 eV to 500μ eV. The feasibility study on using a poly-crystalline silicon as a cold neutron filter and mono-crystalline as a thermal neutron one is given. The optimum crystal thickness, mosaic spread, temperature and cutting plane for efficiently transmitting the thermal reactor neutrons, while rejecting both fast neutrons and gamma rays accompanying the thermal ones for the mono crystalline silicon are also given

  19. Principles of the measurement of residual stress by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Webster, G A; Ezeilo, A N [Imperial Coll. of Science and Technology, London (United Kingdom). Dept. of Mechanical Engineering

    1996-11-01

    The presence of residual stresses in engineering components can significantly affect their load carrying capacity and resistance to fracture. In order to quantify their effect it is necessary to know their magnitude and distribution. Neutron diffraction is the most suitable method of obtaining these stresses non-destructively in the interior of components. In this paper the principles of the technique are described. A monochromatic beam of neutrons, or time of flight measurements, can be employed. In each case, components of strain are determined directly from changes in the lattice spacings between crystals. Residual stresses can then be calculated from these strains. The experimental procedures for making the measurements are described and precautions for achieving reliable results discussed. These include choice of crystal planes on which to make measurements, extent of masking needed to identify a suitable sampling volume, type of detector and alignment procedure. Methods of achieving a stress free reference are also considered. A selection of practical examples is included to demonstrate the success of the technique. (author) 14 figs., 1 tab., 18 refs.

  20. Principles of the measurement of residual stress by neutron diffraction

    International Nuclear Information System (INIS)

    Webster, G.A.; Ezeilo, A.N.

    1996-01-01

    The presence of residual stresses in engineering components can significantly affect their load carrying capacity and resistance to fracture. In order to quantify their effect it is necessary to know their magnitude and distribution. Neutron diffraction is the most suitable method of obtaining these stresses non-destructively in the interior of components. In this paper the principles of the technique are described. A monochromatic beam of neutrons, or time of flight measurements, can be employed. In each case, components of strain are determined directly from changes in the lattice spacings between crystals. Residual stresses can then be calculated from these strains. The experimental procedures for making the measurements are described and precautions for achieving reliable results discussed. These include choice of crystal planes on which to make measurements, extent of masking needed to identify a suitable sampling volume, type of detector and alignment procedure. Methods of achieving a stress free reference are also considered. A selection of practical examples is included to demonstrate the success of the technique. (author) 14 figs., 1 tab., 18 refs

  1. Thermal neutrons streaming in straight duct

    International Nuclear Information System (INIS)

    Jehouani, A.; Boulkheir, M.; Ichaoui, R.

    2000-01-01

    The neutron streaming in duct is due to two phenomena: a) direct propagation and b) reflection on duct wall. We have used the Monte Carlo method to evaluate the ratio of the reflected neutrons flux by the duct wall to the total flux at the exit of the duct for iron and aluminium. Ten neutrons energy groups are considered between 10 -5 eV and 10 eV. A Fortran program is developed to evaluate the neutron double differential albedo. It is shown that the two following approximations are largely justified: i) Three collisions in the duct wall are sufficient to attain the asymptotic limit of the multiscattered neutron double differential albedo ii) The points of entry and exit of the neutron in the duct wall may be considered the same for the multiscattered neutrons. For a punctual source at the mouth of the duct, we have determined the direct and the reflected part of the total thermal neutron flux at the exit of the duct for different lengths and different radius of the duct. For a punctual source, we have found that the major contribution to the total flux of neutrons at the exit is due to the neutron reflection by walls and the reflection contribution decreases when the neutron energy decreases. For a constant length of the duct, the reflected part decreases when the duct radius increases while for the disk shaped source we have found the opposite phenomena. The transmitted neutron flux distribution at the exit of the duct are determined for disk shaped source for different neutron energy and for different distance from the exit center. (author)

  2. Mapping residual and internal stress in materials by neutron diffraction

    International Nuclear Information System (INIS)

    Withers, Ph.J.

    2007-01-01

    Neutron diffraction provides one of the few means of mapping residual stresses deep within the bulk of materials and components. This article reviews the basic scientific methodology by which internal strains and stresses are inferred from recorded diffraction peaks. Both conventional angular scans and time-of-flight measurements are reviewed and compared. Their complementarity with analogous synchrotron X-ray methods is also highlighted. For measurements to be exploited in structural integrity calculations underpinning the safe operation of engineering components, measurement standards have been defined and the major findings are summarised. Examples are used to highlight the unique capabilities of the method showing how it can provide insights ranging from the basic physics of slip mechanisms in hexagonal polycrystalline materials, through the materials optimisation of stress induced transformations in smart nano-materials, to the industrial introduction of novel friction welding processes exploiting stress residual measurements transferred from prototype sub-scale tests to the joining of full-scale aero-engine assemblies. (author)

  3. Direct observation of crystal texture by neutron diffraction topography

    International Nuclear Information System (INIS)

    Tomimitsu, Hiroshi

    1982-02-01

    This document reports the development and the applications of the neutron diffraction topography (NDT), which have been carried out at JAERI in these 10 years. This describes how the substructure of Cu-5%Ge single crystal of large-scale (3 cm in diameter and 10 cm in length) was revealed by the NDT-observation. It was discovered that the specimen crystal was made up from the layer-substructures parallel to (001) and to the [110] growth direction, and that each (001) layer-substructure mentioned above was further subdivided into the central thin sublayer parallel to (001) and thick plates of [100] and [010] directions, attached symmetrically to both sides of the central (001) sublayer with regular intervals. The model of the substructure described above was supported by the calculation of the diffraction intensities. The model of the layer-substructure described above, on the other hand, suggested a simple mechanism of crystal growth of the specimen. This document also reports the NDT-observation of the three-dimensional distribution of the lattice strains within a hot-pressed Ge single crystal, and the equal thickness fringes and the coherent boundaries of a twinned Si crystal. The powerfulness and the reliability of the NDT-technique were thus demonstrated. (author)

  4. Thermal testing of solid neutron shielding materials

    International Nuclear Information System (INIS)

    Boonstra, R.H.

    1992-09-01

    Two legal-weight truck casks the GA-4 and GA-9, will carry four PWR and nine BWR spent fuel assemblies, respectively. Each cask has a solid neutron shielding material separating the steel body and the outer steel skin. In the thermal accident specified by NRC regulations in 10CFR Part 71, the cask is subjected to an 800 degree C environment for 30 minutes. The neutron shield need not perform any shielding function during or after the thermal accident, but its behavior must not compromise the ability of the cask to contain the radioactive contents. In May-June 1989 the first series of full-scale thermal tests was performed on three shielding materials: Bisco Products NS-4-FR, and Reactor Experiments RX-201 and RX-207. The tests are described in Thermal Testing of Solid Neutron Shielding Materials, GA-AL 9897, R. H. Boonstra, General Atomics (1990), and demonstrated the acceptability of these materials in a thermal accident. Subsequent design changes to the cask rendered these materials unattractive in terms of weight or adequate service temperature margin. For the second test series, a material specification was developed for a polypropylene based neutron shield with a softening point of at least 280 degree F. The neutron shield materials tested were boronated (0.8--4.5%) polymers (polypropylene, HDPE, NS-4). The Envirotech and Bisco materials are not polypropylene, but were tested as potential backup materials in the event that a satisfactory polypropylene could not be found

  5. An in situ neutron diffraction study of shape setting shape memory NiTi

    International Nuclear Information System (INIS)

    Benafan, O.; Padula, S.A.; Noebe, R.D.; Brown, D.W.; Clausen, B.; Vaidyanathan, R.

    2013-01-01

    A bulk polycrystalline Ni 49.9 Ti 50.1 (at.%) shape memory alloy specimen was shape set while neutron diffraction spectra were simultaneously acquired. The objective was to correlate internal stress, phase volume fraction, and texture measurements (from neutron diffraction spectra) with the macroscopic stress and shape changes (from load cell and extensometry measurements) during the shape setting procedure and subsequent shape recovery. Experimental results showed the evolution of the martensitic transformation (lattice strains, phase fractions and texture) against external constraints during both heating and cooling. Constrained heating resulted in a build-up of stresses during the martensite to austenite transformation, followed by stress relaxation due to thermal expansion, final conversion of retained martensite, and recovery processes. Constrained cooling also resulted in stress build-up arising from thermal contraction and early formation of martensite, followed by relaxation as the austenite fully transformed to martensite. Comparisons were also made between specimens pre-shape set and post-shape set with and without external constraints. The specimens displayed similar shape memory behavior consistent with the microstructure of the shape set sample, which was mostly unchanged by the shape setting process and similar to that of the as-received material

  6. Thermal testing of solid neutron shielding materials

    International Nuclear Information System (INIS)

    Boonstra, R.H.

    1990-03-01

    The GA-4 and GA-9 spent fuel shipping casks employ a solid neutron shielding material. During a hypothetical thermal accident, any combustion of the neutron shield must not compromise the ability of the cask to contain the radioactive contents. A two-phase thermal testing program was carried out to assist in selecting satisfactory shielding materials. In the first phase, small-scale screening tests were performed on nine candidate materials using ASTM procedures. From these initial results, three of the nine candidates were chosen for inclusion in the second phase of testing, These materials were Bisco Products NS-4-FR, Reactor Experiments 201-1, and Reactor Experiments 207. In the second phase, each selected material was fabricated into a test article which simulated a full-scale of neutron shield from the cask. The test article was heated in an environmental prescribed by NRC regulations. Results of this second testing phase showed that all three materials are thermally acceptable

  7. Thermal testing of solid neutron shielding materials

    International Nuclear Information System (INIS)

    Boonstra, R.N.

    1990-01-01

    The GA-4 and GA-9 spent fuel shipping casks employ a solid neutron shielding material. During a hypothetical thermal accident, any combustion of the neutron shield must not compromise the ability of the cask to contain the radioactive contents. A two-phase thermal testing program was carried out to assist in selecting satisfactory shielding materials. In the first phase, small-scale screening tests were performed on nine candidate materials using ASTM procedures. From these initial results, three of the nine candidates were chosen for inclusion in the second phase of testing. These materials were Bisco Products NS-4-FR, Reactor Experiments 201-1, and Reactor Experiments 207. In the second phase, each selected material was fabricated into a test article which simulated a full-scale section of neutron shield from the cask. The test article was heated in an environment prescribed by NRC regulations. Results of this second testing phase show that all three materials are thermally acceptable

  8. Neutronics methods for thermal radiative transfer

    International Nuclear Information System (INIS)

    Larsen, E.W.

    1988-01-01

    The equations of thermal radiative transfer are time discretized in a semi-implicit manner, yielding a linear transport problem for each time step. The governing equation in this problem has the form of a neutron transport equation with fission but no scattering. Numerical methods are described, whose origins lie in neutron transport, and that have been successfully adapted to this new problem. Acceleration methods that have been developed specifically for the radiative transfer problem, but may have generalizations applicable in neutronics problems, are also discussed

  9. The early development of neutron diffraction: science in the wings of the Manhattan Project.

    Science.gov (United States)

    Mason, T E; Gawne, T J; Nagler, S E; Nestor, M B; Carpenter, J M

    2013-01-01

    Although neutron diffraction was first observed using radioactive decay sources shortly after the discovery of the neutron, it was only with the availability of higher intensity neutron beams from the first nuclear reactors, constructed as part of the Manhattan Project, that systematic investigation of Bragg scattering became possible. Remarkably, at a time when the war effort was singularly focused on the development of the atomic bomb, groups working at Oak Ridge and Chicago carried out key measurements and recognized the future utility of neutron diffraction quite independent of its contributions to the measurement of nuclear cross sections. Ernest O. Wollan, Lyle B. Borst and Walter H. Zinn were all able to observe neutron diffraction in 1944 using the X-10 graphite reactor and the CP-3 heavy water reactor. Subsequent work by Wollan and Clifford G. Shull, who joined Wollan's group at Oak Ridge in 1946, laid the foundations for widespread application of neutron diffraction as an important research tool.

  10. 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.

  11. Neutron diffraction measurements for the determination of residual stresses in MMC tensile and fatigue specimens

    DEFF Research Database (Denmark)

    Fiori, F.; Girardin, E.; Giuliani, A.

    2000-01-01

    have been performed at RISO (Roskilde, DK) and HMI-BENSC (Berlin, D), for the determination of residual stress in AA2124 + 17% SiCp and AA359 + 20% SiCp specimens, submitted to tensile and fatigue tests. For each of the investigated samples, the macrostress has been separated from the elastic......, residual stresses are present in both the matrix and the particles microstructure, prior to any macroscopic loading. They vary with the temperature and with the type and level of loading imposed to the material, having a strong influence on the mechanical behaviour of MMCs. Neutron diffraction measurements...... and thermal mismatch microstresses. The results show that, in general, the main contribution to the stress state of both matrix and reinforcement is given by the thermal microstresses, already existing due to heat treatment prior to mechanical tests. (C) 2000 Elsevier Science B.V. All rights reserved....

  12. Refinement of the crystal structure of malachite, Cu2(OH)2CO3, by neutron diffraction

    International Nuclear Information System (INIS)

    Zigan, F.; Joswig, W.; Schuster, H.D.; Mason, S.A.

    1977-01-01

    The crystal structure of malachite is refined (R = 0,021) with the intensity values of 635 independent neutron reflexions from a single crystal, rather free from absorption and extinction. Concerning the structural geometry, no essential deviations occur from the known results of x-ray diffraction. The thermal elongations are generally largest about the normal to the (201) layers, between which the bonding is relatively weak. In both of the (medium, bent) OH...O hydrogen bonds, the anisotropic thermal parameters, converted according to the riding model, are - with certain restrictions - in agreement with the measured infrared spectrum as well as with frequencies and directions of the proton vibration calculated from the bonding geometry on the basis of a theoretical model. (orig.) [de

  13. Measurement of thermal neutron capture cross section

    International Nuclear Information System (INIS)

    Huang Xiaolong; Han Xiaogang; Yu Weixiang; Lu Hanlin; Zhao Wenrong

    2001-01-01

    The thermal neutron capture cross sections of 71 Ga(n, γ) 72 Ga, 94 Zr(n, γ) 95 Zr and 191 Ir(n, γ) 192 Ir m1+g,m2 reactions were measured by using activation method and compared with other measured data. Meanwhile the half-life of 72 Ga was also measured. The samples were irradiated with the neutron in the thermal column of heavy water reactor of China Institute of Atomic Energy. The activities of the reaction products were measured by well-calibrated Ge(Li) detector

  14. Thermal neutron albedo measurements for multilithic reflectors

    International Nuclear Information System (INIS)

    Mehboob, Khurram; Ahmed, Raheel; Ali, Majid; Tabassam, Uzma

    2013-01-01

    Highlights: • Measurement of thermal neuron albedo for multilithic reflectors. • Modeling of experiments in MATLAB. • Comparison of numerical calculated and experimental values. • Study of thermal neutron albedo in different multilayered shielding. - Abstract: An experimental measurement of the thermal neutron (0.025 eV) albedo (αth) has been carried out for multilithic shielding by using Am–Be neutron source and BF 3 detector. The measured saturation value for the thermal albedo of paraffin wax has been found to be 0.734 ± 0.020, which is in close agreement to the corresponding value 0.83 quoted in the literature. The thermal neutron albedo has been measured for the multilayered shielding in copper–wood, copper–aluminum, wood–paraffin and paraffin–iron combinations in horizontal geometric configurations. Modeling and numerical simulation have been carried out by developing a MATLAB code which solves the diffusion equation in order to calculate the experimental results. Good agreement has been found between the numerical calculated and experimental results. The uncertainties in the measurements have also been calculated based on error propagation of the underlying Poisson distribution

  15. Enstatite, Mg/sub 2/Si/sub 2/O/sub 6/: A neutron diffraction refinement of the crystal structure and a rigid-body analysis of the thermal vibration

    Energy Technology Data Exchange (ETDEWEB)

    Ghose, S.; Schomaker, V.; McMullan, R.K.

    1986-01-01

    Synthetic enstatite, Mg/sub 2/Si/sub 2/O/sub 6/, is orthorhombic, space group Pbca, with eight formula units per cell and lattice parameters a = 18.235(3), b = 8.818(1), c = 5.179(1) A at 23/sup 0/C. A least-squares structure refinement based on 1790 neutron intensity data converged with an agreement factor R(F/sup 2/) = 0.032, yielding Mg-O and Si-O bond lengths with standard deviations of 0.0007 and 0.0008 A, respectively. The variations observed in the Si-O bond lengths within the silicate tetrahedra A and B are caused by the differences in primary coordination of the oxygen atoms and the proximity of the magnesium ions to the silicon atoms. The latter effect is most pronounced for the bridging bonds of tetrahedron. A. The smallest O-Si-O angle is the result of edge-sharing by the Mg(2) octahedron and the A tetrahedron. An analysis of rigid-body thermal vibrations of the two crystallographically independent (SiO/sub 4/) tetrahedra indicates considerable librational motion, leading to a thermal correction of apparent Si-O bond lengths as large as +0.002 A at room temperature.

  16. Method for determining thermal neutron decay times of earth formations

    International Nuclear Information System (INIS)

    Arnold, D.M.

    1976-01-01

    A method is disclosed for measuring the thermal neutron decay time of earth formations in the vicinity of a well borehole. A harmonically intensity modulated source of fast neutrons is used to irradiate the earth formations with fast neutrons at three different intensity modulation frequencies. The tangents of the relative phase angles of the fast neutrons and the resulting thermal neutrons at each of the three frequencies of modulation are measured. First and second approximations to the earth formation thermal neutron decay time are derived from the three tangent measurements. These approximations are then combined to derive a value for the true earth formation thermal neutron decay time

  17. Time-of-flight pulsed neutron diffraction of molten salts

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, Y; Misawa, M; Suzuki, K [Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals

    1975-06-01

    In this work, the pulsed neutron diffraction of molten alkali metal nitrate and bismuth trihalide was measured by the time-of-flight method. An electron linear accelerator was used as the pulsed neutron source. All the measurements were carried out with the T-O-F neutron diffractometer installed on the 300 MeV electron lineac. Molten NaNO/sub 3/ and RbNO/sub 3/ were adopted as the samples for alkali metal nitrate. The measurement is in progress for KNO/sub 3/ and LiNO/sub 3/. As the first step of the study on bismuth-bismuth trihalide system, the temperature dependence of structure factors was observed for BiCl/sub 3/, BiBr/sub 3/ and BiI/sub 3/ in the liquid state. The structure factors Sm(Q) for molten NaNO/sub 3/ at 340/sup 0/C and RbNO/sub 3/ at 350/sup 0/C were obtained, and the form factor F/sub 1/(Q) for single NO/sub 3//sup -/ radical with equilateral triangle structure was calculated. In case of molten NaNO/sub 3/, the first peak of Sm(Q) is simply smooth and a small hump can be observed in the neighbourhood of the first minimum Q position. The first peak of Sm(Q) for molten RbNO/sub 3/ is divided into two peaks, whereas a hump at the first minimum becomes big, and shifts to the low Q side of the second peak. The size of the NO/sub 3//sup -/ radical in molten NaNO/sub 3/ is a little smaller than that in molten RbNO/sub 3/. The values of the bond length in the NO/sub 3//sup -/ radical are summarized for crystal state and liquid state. The temperature dependence of the structure factor S(Q) was observed for BiCl/sub 3/, BiBr/sub 3/ and BiI/sub 3/, and shown in a figure.

  18. Neutron diffraction measurements of microstress and macrostress in composites

    International Nuclear Information System (INIS)

    Tanaka, Keisuke; Akiniwa, Yoshiaki

    2001-01-01

    For accurate stress measurements, precise values of the diffraction elastic constant (DEC) is required. The theoretical prediction of DEC of engineering materials on the basis of the self-consistent model agreed well with the experimental results of sintered alumina with various porosities. From the experimental results of DEC of sintered silicon nitride, the elastic anisotropy of single crystals of β-silicon nitride was estimated with the simplex method. The phase stress measured in the matrix and SiC particles of composite subjected to the applied stress agreed well with the theoretical prediction. The macrostress calculated from the phase stress by using the rule of mixture was equal to the applied stress. The measured values of the thermal residual stress in ceramic composites of alumina mixed with various volume fractions of zirconia agreed well with the theoretical prediction based on Eshelby's inclusion model. (author)

  19. In-situ neutron diffraction during biaxial deformation

    International Nuclear Information System (INIS)

    Van Petegem, S.; Wagner, J.; Panzner, T.; Upadhyay, M.V.; Trang, T.T.T.; Van Swygenhoven, H.

    2016-01-01

    A change in strain path may have a significant effect on the mechanical response of metals. In order to understand or even predict the macroscopic behaviour under such conditions a detailed knowledge on the microstructural evolution is crucial. Yet relatively little work has been done to quantify and understand how the inter- and intragranular strains are affected during a change in strain path. In this work we present a new multiaxial deformation rig that allows performing in situ proportional and non-proportional loading under neutron diffraction. We demonstrate the capabilities of this new setup for the case of a 316 L stainless steel. We show that the nature and magnitude of intergranular strain strongly depends on the applied stress state and demonstrate that micro yielding and internal strain recovery are responsible for the observed transient softening during a 90° strain path change. We anticipate that this new characterization method will provide previously inaccessible microstructural data that can serve as input for benchmarking current state-of-the-art crystal plasticity models.

  20. Study on the dose distribution of the mixed field with thermal and epi-thermal neutrons for neutron capture therapy

    International Nuclear Information System (INIS)

    Kobayashi, Tooru; Sakurai, Yoshinori; Kanda, Keiji

    1994-01-01

    Simulation calculations using DOT 3.5 were carried out in order to confirm the characteristics of depth-dependent dose distribution in water phantom dependent on incident neutron energy. The epithermal neutrons mixed to thermal neutron field is effective improving the thermal neutron depth-dose distribution for neutron capture therapy. A feasibility study on the neutron energy spectrum shifter was performed using ANISN-JR for the KUR Heavy Water Facility. The design of the neutron spectrum shifter is feasible, without reducing the performance as a thermal neutron irradiation field. (author)

  1. 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

  2. A comparison of dilatometry and in-situ neutron diffraction in tracking bulk phase transformations in a martensitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Christien, F., E-mail: frederic.christien@univ-nantes.fr [Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, Rue Christian Pauc, BP 50609, 44306 Nantes Cedex 3 (France); Telling, M.T.F. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX (United Kingdom); Department of Materials, University of Oxford, Parks Road, Oxford (United Kingdom); Knight, K.S. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX (United Kingdom); Department of Earth Sciences, The Natural History Museum, Cromwell Road, London (United Kingdom)

    2013-08-15

    Phase transformations in the 17-4PH martensitic stainless steel have been studied using different in-situ techniques, including dilatometry and high resolution neutron diffraction. Neutron diffraction patterns were quantitatively processed using the Rietveld refinement method, allowing the determination of the temperature-dependence of martensite (α′, bcc) and austenite (γ, fcc) phase fractions and lattice parameters on heating to 1000 °C and then cooling to room temperature. It is demonstrated in this work that dilatometry doesn't permit an accurate determination of the end temperature (Ac3) of the α′ → γ transformation which occurs upon heating to high temperature. The analysis of neutron diffraction data has shown that the respective volumes of the two phases become very close to each other at high temperature, thus making the dilatometric technique almost insensitive in that temperature range. However, there is a very good agreement between neutron diffraction and dilatometry at lower temperature. The martensitic transformation occurring upon cooling has been analysed using the Koistinen–Marburger equation. The thermal expansion coefficients of the two phases have been determined in addition. A comparison of the results obtained in this work with data from literature is presented. - Highlights: • Martensite is still present at very high temperature (> 930 °C) upon heating. • The end of austenitisation cannot be accurately monitored by dilatometry. • The martensite and austenite volumes become similar at high temperature (> ∼ 850 °C)

  3. Thermal and magnetic properties of neutron matter

    International Nuclear Information System (INIS)

    Abd-Alla, M.; Ragab, H.S.; Hassan, M.Y.M.

    1990-01-01

    The Thomas-Fermi model is used to calculate the equation of state of thermal polarized neutron matter applying Seyler-Blanchard interaction. The resulting equation of state is stiff and has a small dependence on both the temperature and the spin excess parameter. We expand the Fermi integrals in powers of temperature up to second order to examine the T 2 approximation for neutron matter. It is found to be reliable up to T = 10 MeV. We also studied the ferromagnetic transition in neutron matter. We found a ferromagnetic transition at density ρ ≅ 2ρ0. This ferromagnetic transition is found to have a small dependence on both the temperature and the spin excess parameter. We also studied the dependence of the effective mass and the sound velocity for polarized neutron matter on temperature. (author). 36 refs, 17 figs

  4. Thermal neutron spectrum distribution in TRIGA fuels

    International Nuclear Information System (INIS)

    Gui Ah Auu; Harasawa, Susumu; An, Shigehiro

    1989-01-01

    The dependence of thermal neutron spectrum in TRIGA fuel cell on fuel temperature and TRIGA fuel types were studied using LIBP and THERMOS codes. Some characteristics of the TRIGA fuel including its prompt negative temperature coefficient of reactivity were explained using the results of the study. (author)

  5. Instrumentation to handle thermal polarized neutron beams

    NARCIS (Netherlands)

    Kraan, W.H.

    2004-01-01

    In this thesis we investigate devices needed to handle the polarization of thermal neutron beams: Ï/2-flippers (to start/stop Larmor precession) and Ï-flippers (to reverse polarization/precession direction) and illustrate how these devices are used to investigate the properties of matter and of the

  6. Time-of-flight diffraction at pulsed neutron sources: An introduction to the symposium

    International Nuclear Information System (INIS)

    Jorgensen, J.D.

    1994-01-01

    In the 25 years since the first low-power demonstration experiments, pulsed neutron sources have become as productive as reactor sources for many types of diffraction experiments. The pulsed neutron sources presently operating in the United States, England, and Japan offer state of the art instruments for powder and single crystal diffraction, small angle scattering, and such specialized techniques as grazing-incidence neutron reflection, as well as quasielastic and inelastic scattering. In this symposium, speakers review the latest advances in diffraction instrumentation for pulsed neutron sources and give examples of some of the important science presently being done. In this introduction to the symposium, I briefly define the basic principles of pulsed neutron sources, review their development, comment in general terms on the development of time-of-flight diffraction instrumentation for these sources, and project how this field will develop in the next ten years

  7. Single-crystal neutron diffraction at the Australian Replacement Research Reactor

    International Nuclear Information System (INIS)

    Klooster, W.T.

    2001-01-01

    The purpose of the workshop was to: identify the future needs and opportunities for single-crystal neutron diffraction, and specify instrument requirements. important number of experiments. The conclusion of the workshop deliberation was that Australia has a diverse community of users of single-crystal neutron diffraction. A (quasi)-Laue image-plate diffractometer allows the fastest throughput by far, but would exclude an important number of experiments. Most of these could be covered by the additional possibility to locate the image-plate detector on a monochromatic beam. Therefore it was recommend both a white thermal beam and a monochromatic beam (λ= 1 to 2.4 Angstroms) for an image-plate detector. At little additional cost the existing 2TanA instrument could be located semi-permanently on the same monochromatic beam, thus offering three quite different types of single-crystal instruments. Small improvements could be made to the 2TanA instrument to cater for the remaining experiments not suited to an image-plate diffractometer: exchange of the Eulerian cradle for an automated tilt goniometer for extremely bulky sample environment (cryomagnets, large pressure cells), optional larger area detector, analyser crystal. It was recommended that an Instrument Advisory Team will be assembled, and will help in specifying, designing and commissioning the instrument

  8. X-ray and Neutron Diffraction in the Study of Organic Crystalline Hydrates

    Directory of Open Access Journals (Sweden)

    Katharina Fucke

    2010-07-01

    Full Text Available A review. Diffraction methods are a powerful tool to investigate the crystal structure of organic compounds in general and their hydrates in particular. The laboratory standard technique of single crystal X-ray diffraction gives information about the molecular conformation, packing and hydrogen bonding in the crystal structure, while powder X-ray diffraction on bulk material can trace hydration/dehydration processes and phase transitions under non-ambient conditions. Neutron diffraction is a valuable complementary technique to X-ray diffraction and gives highly accurate hydrogen atom positions due to the interaction of the radiation with the atomic nuclei. Although not yet often applied to organic hydrates, neutron single crystal and neutron powder diffraction give precise structural data on hydrogen bonding networks which will help explain why hydrates form in the first place.

  9. Dynamical theory of neutron diffraction. [One-body Schroedinger equation, review

    Energy Technology Data Exchange (ETDEWEB)

    Sears, V F [Atomic Energy of Canada Ltd., Chalk River, Ontario. Chalk River Nuclear Labs.

    1978-10-01

    We present a review of the dynamical theory of neutron diffraction by macroscopic bodies which provides the theoretical basis for the study of neutron optics. We consider both the theory of dispersion, in which it is shown that the coherent wave in the medium satisfies a macroscopic one-body Schroedinger equation, and the theory of reflection, refraction, and diffraction in which the above equation is solved for a number of special cases of interest. The theory is illustrated with the help of experimental results obtained over the past 10 years by a number of new techniques such as neutron gravity refractometry. Pendelloesung interference, and neutron interferometry.

  10. The Thermal Neutron Beam Option for NECTAR at MLZ

    Science.gov (United States)

    Mühlbauer, M. J.; Bücherl, T.; Genreith, C.; Knapp, M.; Schulz, M.; Söllradl, S.; Wagner, F. M.; Ehrenberg, H.

    The beam port SR10 at the neutron source FRM II of Heinz Maier-Leibnitz Zentrum (MLZ) is equipped with a moveable assembly of two uranium plates, which can be placed in front of the entrance window of the beam tube via remote control. With these plates placed in their operating position the thermal neutron spectrum produced by the neutron source FRM II is converted to fission neutrons with 1.9 MeV of mean energy. This fission neutron spectrum is routinely used for medical applications at the irradiation facility MEDAPP, for neutron radiography and tomography experiments at the facility NECTAR and for materials testing. If, however, the uranium plates are in their stand-by position far off the tip of the beam tube and the so-called permanent filter for thermal neutrons is removed, thermal neutrons originating from the moderator tank enter the beam tube and a thermal spectrum becomes available for irradiation or activation of samples. By installing a temporary flight tube the beam may be used for thermal neutron radiography and tomography experiments at NECTAR. The thermal neutron beam option not only adds a pure thermal neutron spectrum to the energy ranges available for neutron imaging at MLZ instruments but it also is an unique possibility to combine two quite different neutron energy ranges at a single instrument including their respective advantages. The thermal neutron beam option for NECTAR is funded by BMBF in frame of research project 05K16VK3.

  11. Simultaneous thermal neutron decay time and porosity logging system

    International Nuclear Information System (INIS)

    Smith, H.D. Jr.; Smith, M.P.; Schultz, W.E.

    1979-01-01

    A simultaneous pulsed neutron porosity and thermal neutron capture cross section logging system is provided for radiological well logging of subsurface earth formations. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector, and a combination gamma ray and fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations; and, during the bursts, the fast neutron and epithermal neutron populations are sampled. During the interval between bursts the thermal neutron capture gamma ray population is sampled in two or more time intervals. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity phi. The capture gamma ray measurements are combined to provide a simultaneous determination of the thermal neutron capture cross section Σ

  12. THERMAL: A routine designed to calculate neutron thermal scattering

    International Nuclear Information System (INIS)

    Cullen, D.E.

    1995-01-01

    THERMAL is designed to calculate neutron thermal scattering that is isotropic in the center of mass system. At low energy thermal motion will be included. At high energies the target nuclei are assumed to be stationary. The point of transition between low and high energies has been defined to insure a smooth transition. It is assumed that at low energy the elastic cross section is constant in the center of mass system. At high energy the cross section can be of any form. You can use this routine for all energies where the elastic scattering is isotropic in the center of mass system. In most materials this will be a fairly high energy

  13. Thermal testing of solid neutron shielding materials

    International Nuclear Information System (INIS)

    Boonstra, R.H.

    1993-01-01

    In May-June 1989 the first series of full-scale thermal tests was performed on three shielding materials: Bisco Products NS-4-FR, and Reactor Experiments RX-201 and RX-207. The tests are described in Thermal Testing of Solid Neutron Shielding Materials, GA-A19897, R.H. Boonstra, General Atomics (1990), and demonstrated the acceptability of these materials in a thermal accident. Subsequent design changes to the cask rendered these materials unattractive in terms of weight or adequate service temperature margin. For the second test series a material specification was developed for a polypropylene based neutron shield with a softening point of at least 280degF. Table 1 lists the neutron shield materials tested. The Envirotech and Bisco materials are not polypropylene, but were tested as potential backup materials in the event that a satisfactory polypropylene could not be found. The Bisco modified NS-4 and Reactor Experiments HMPP are both acceptable materials from a thermal accident standpoint for use in the shipping cask. Tests of the Kobe PP-R01 and Envirotech HDPE were stopped for safety reasons, due to inability to deal with the heavy smoke, before completion of the 30-minute heating phase. However these materials may prove satisfactory if they could undergo the complete heating. (J.P.N.)

  14. Neutron diffraction determination of mean-square atomic displacements

    International Nuclear Information System (INIS)

    Tibballs, J.E.; Feteris, S.M.; Barnea, Z.

    1981-01-01

    Integrated intensities for Bragg reflection of neutrons from single crystals of the III-V compounds, InAs and GaSb, have been measured at room temperature. The data were collected at two wavelengths, 0.947 A and 1.241 A, in order to establish the adequacy of a correction for moderate to severe anisotropic extinction. Data were also obtained for InAs at four temperatures from 408 K to 933 K. Corrections for thermal diffuse scattering were applied. The results were analysed in the one-particle potential approximation with terms to fourth-order in the atomic displacements u = (u 1 , u 2 , u 3 ). At 296 K, the mean-square components were determined for In, 0.0116(2)A 2 and As, 0.0102 (1)A 2 ; for Ga, 0.0120(3)A 2 and Sb, 0.0107(3)A 2 . The third-order coefficients for InAs are comparable with those for Si and Ge, those for GaSb with those for zinc chalcogenides. Non-harmonic behaviour in InAs is observed below 400 K

  15. Application of a high-temperature neutron diffraction apparatus to the study of refractory oxides

    International Nuclear Information System (INIS)

    Aldebert, P.; Badie, J.-M.; Buevoz, J.-L.; Roult, G.

    1975-01-01

    A furnace allowing studies of refractory materials by neutron diffraction in situ up to 2500 deg C is described. It is fitted on to a new type of time of flight spectrometer the pulsed source of which is given by a correlation chopper. The advantages of this technique in comparison with fixed-wavelength goniometers are developped. The examination at high temperature of several refractory oxides has been carried out with this experimental device. The thermal expansion curve of α alumina has been established with accuracy up to near the melting point. Several high temperature cristalline forms, X form La 2 O 3 , the tetragonal and cubic ZrO 2 , tetragonal HfO 2 , have been studied. Concerning the latter two, the case of their solid solutions 2MO 2 -M' 2 O 3 (with M=Hf or Zr and M'=La or Y) has also been considered, at room temperature only [fr

  16. A neutron diffraction study on deuterated Rochelle salt structure at - 195degC paraelectric phase

    International Nuclear Information System (INIS)

    Iwata, Yutaka; Mitani, Shigeshi; Fukui, Susumu; Shibuya, Iwao

    1989-01-01

    Neutron diffraction study on the low temperature paraelectric phase of Rochelle salt was performed using deuterated single crystal specimen. Large anisotropic thermal motions of atoms are found to be prevailing in the lower paraelectric phase. This indicates the disordering of atoms and the analysis by two-site split-atom method showed that a split atom model holds equally well with an ordinary non-split model. By connecting split positions selectively, a disordered paraelectric structure, which is composed of half-occupied units, was obtained. These units can be regarded as ones in the ferroelectric phase according to a deduction from an order-disorder phase transition scheme. A possibility of existence of the 'local disorder' of O(5)-H group in the tartrate molecule was examined by Fourier method and a result proved to be negative. Present disordered model gives better understanding to the phase transition scheme of Rochelle salt than the local disorder model case. (author)

  17. Study on Destructuring effect of trehalose on water by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Branca, C.; Maisano, G.; Migliardo, F. [Dipartimento di Fisica and INFM, Universita' di Messina, PO Box 55, 98166 Messina (Italy); Magazu' , V. [Facolta di Ingeeneria, Universita' di Messina, 98166 Messina (Italy); Soper, A.K. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)

    2002-07-01

    In this work results on trehalose/water solutions by neutron diffraction are reported. The study of the partial structure factors and spatial distribution functions gives evidence of a decreasing tetrahedrality degree of water and justifies its cryoprotectant effectiveness. (orig.)

  18. Neutron scattering and diffraction instrument for structural study on biology in Japan

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-31

    Neutron scattering and diffraction instruments in Japan which can be used for structural studies in biology are briefly introduced. Main specifications and general layouts of the instruments are shown.

  19. Study on Destructuring effect of trehalose on water by neutron diffraction

    CERN Document Server

    Branca, C; Migliardo, F; Magazù, V; Soper, A K

    2002-01-01

    In this work results on trehalose/water solutions by neutron diffraction are reported. The study of the partial structure factors and spatial distribution functions gives evidence of a decreasing tetrahedrality degree of water and justifies its cryoprotectant effectiveness. (orig.)

  20. Structure analysis of liquids and disordered materials using pulsed neutron diffraction and total scattering

    International Nuclear Information System (INIS)

    Suzuya, Kentaro

    2011-01-01

    Neutron diffraction·total scattering at pulsed neutron source is a powerful method to analyze the complex structure of disordered materials: liquids, glasses, amorphous materials and disordered crystals. The basic idea of the structure of disordered materials, the fundamental diffraction theory for disordered materials, and structure analysis of disordered materials using pulsed neutron diffraction·total scattering technique (TOF method) are described in detail. In addition, the precise information of the world highest class J-PARC MLF spallation neutron source and typical J-PARC neutron total scattering instrument NOVA are also given. Recent structural modelling methods of disordered materials such like reverse Monte Carlo (RMC) simulation method is briefly described using an example of the analysis of a typical disordered material silica glass. (author)

  1. Comparative study of structural properties of trehalose water solutions by neutron diffraction, synchrotron radiation and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Cesaro, A.; Magazu, V.; Migliardo, F.; Sussich, F.; Vadala, M

    2004-07-15

    Neutron diffraction measurements combined with H/D substitution have been performed on trehalose aqueous solutions as a function of temperature and concentration by using the SANDALS diffractometer at ISIS Facility (UK). The findings point out a high capability of trehalose to strongly affect the tetrahedral hydrogen bond network of water. The neutron diffraction results are also compared with simulation and experimental data obtained by synchrotron radiation on the phospholipid bilayer membranes (DPPC)/trehalose/H{sub 2}O ternary system.

  2. High-resolution neutron diffraction studies of biological and industrial fibres

    Energy Technology Data Exchange (ETDEWEB)

    Langan, P; Mason, S A [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Fuller, W; Forsyth, V T; Mahendrasingam, A; Shotton, M; Simpson, L [Keele Univ. (United Kingdom); Grimm, H [FZ, Juelich (Germany); Leberman, R [EMBL, (Country Unknown)

    1997-04-01

    Neutron diffraction is becoming an important tool for studying fibres due to its complementarity to X-ray diffraction. Unlike X-rays, scattering of neutrons by polymer atoms is not a function of their atomic number. In high-resolution studies (1.5-3 A) on D19 deuteration (replacing H by D) is being used to change the relative scattering power of chosen groups making them easier to locate. Recent studies on DNA and cellulose are described. (author). 6 refs.

  3. Real time neutron diffraction and NMR of the Empress II glass-ceramic system.

    Science.gov (United States)

    O'Donnell, M D; Hill, R G; Karpukhina, N; Law, R V

    2011-10-01

    This study reports real time neutron diffraction on the Empress II glass-ceramic system. The commercial glass-ceramics was characterized by real time neutron diffraction, ³¹P and ²⁹Si solid-state MAS-NMR, DSC and XRD. On heating, the as-received glass ceramic contained lithium disilicate (Li₂Si₂O₅), which melted with increasing temperature. This was revealed by neutron diffraction which showed the Bragg peaks for this phase had disappeared by 958°C in agreement with thermal analysis. On cooling lithium metasilicate (Li₂SiO₃) started to form at around 916°C and a minor phase of cristobalite at around 852°C. The unit cell volume of both Li-silicate phases increased linearly with temperature at a rate of +17×10⁻³ ų.°C⁻¹. Room temperature powder X-ray diffraction (XRD) of the material after cooling confirms presence of the lithium metasilicate and cristobalite as the main phases and shows, in addition, small amount of lithium disilicate and orthophosphate. ³¹P MAS-NMR reveals presence of the lithiorthophosphate (Li₃PO₄) before and after heat treatment. The melting of lithium disilicate on heating and crystallisation of lithium metasilicate on cooling agree with endothermic and exotermic features respectively observed by DSC. ²⁹Si MAS-NMR shows presence of lithium disilicate phase in the as-received glass-ceramic, though not in the major proportion, and lithium metasilicate in the material after heat treatment. Both phases have significantly long T₁ relaxation time, especially the lithium metasilicate, therefore, a quantitative analysis of the ²⁹Si MAS-NMR spectra was not attempted. Significance. The findings of the present work demonstrate importance of the commercially designed processing parameters in order to preserve desired characteristics of the material. Processing the Empress II at a rate slower than recommended 60°C min⁻¹ or long isothermal hold at the maximal processing temperature 920°C can cause

  4. X-ray and neutron diffraction studies of crystallinity in hydroxyapatite coatings.

    Science.gov (United States)

    Girardin, E; Millet, P; Lodini, A

    2000-02-01

    To standardize industrial implant production and make comparisons between different experimental results, we have to be able to quantify the crystallinity of hydroxyapatite. Methods of measuring crystallinity ratio were developed for various HA samples before and after plasma spraying. The first series of methods uses X-ray diffraction. The advantage of these methods is that X-ray diffraction equipment is used widely in science and industry. In the second series, a neutron diffraction method is developed and the results recorded are similar to those obtained by the modified X-ray diffraction methods. The advantage of neutron diffraction is the ability to obtain measurements deep inside a component. It is a nondestructive method, owing to the very low absorption of neutrons in most materials. Copyright 2000 John Wiley & Sons, Inc.

  5. Cell death following thermal neutron exposure

    Energy Technology Data Exchange (ETDEWEB)

    Paterson, L.C. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Atanackovic, J. [Ontario Power Generation, Toronto, Ontario (Canada); Boyer, C. [Canadian Neutron Beam Centre, Chalk River, Ontario (Canada); El-Jaby, S.; Priest, N.D. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Seymour, C.B.; Boreham, D.R. [McMaster Univ., Hamilton, Ontario (Canada); Richardson, R.B. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2014-07-01

    When individuals are exposed to unknown external ionizing radiation, it is desirable to have the means to assess both the absorbed dose received (Gy) and the radiation quality. Yet, conventional biodosimetry techniques, specifically the dicentric chromosome assay, cannot differentiate between the damage caused by high- and low-linear energy transfer (LET) exposures. Frequencies of apoptosis and necrosis, may provide an alternative method that assesses both the absorbed dose and radiation quality after unknown exposures. For this preliminary study, human lymphocytes were irradiated with {sup 60}Co gamma rays and thermal neutrons. Both apoptosis and necrosis increased with increasing gamma dose. In contrast, no dose-response was observed following thermal neutron exposure at doses up to 2.61 Gy. (author)

  6. Residual stress measurements by X-ray and neutron diffractions in heat-treated SiCw/A2014 composites

    International Nuclear Information System (INIS)

    Ohnuki, Takahisa; Fujita, Motoo; Tomota, Yo; Ono, Masayoshi

    1998-01-01

    Residual stresses due to various heat treatments in a 22 volume percent SiC whisker/A2014 metal matrix composite (MMC) were measured by using X-ray and neutron diffractions. Micro residual stresses generated from the differences in thermal expansion coefficients of the constituents and macro residual stresses associated with different cooling rates in the outer and inner regions of an MMC specimen must be distinguished in X-ray stress measurements. The conventional sin 2 ψ method under an assumption of plane stress condition has been found not to be applicable to the present MMC, because interactions among whiskers in the X-ray penetrating area yields σ 33 where the x 3 -axis is normal with respect to specimen's surface. An average value of σ 33 can be measured by X-ray diffraction technique, but does not seem enough to evaluate micro residual stresses. It is found that neutron diffraction is the most powerful method to measure micro residual stresses in the constituents. Elastic residual strains obtained by neutron diffraction in solution treated or T6 heat treated samples show good agreements with predictions calculated by using Eshelby inclusion theory coupled with the Mori-Tanaka mean field concept, indicating that the influence of stress relaxation is negligible. In addition, internal stresses relaxations during holding at room temperature, slow cooling from solution treatment temperature, or subzero cooling are discussed. (author)

  7. The early development of neutron diffraction: science in the wings of the Manhattan Project

    Energy Technology Data Exchange (ETDEWEB)

    Mason, T. E., E-mail: masont@ornl.gov; Gawne, T. J.; Nagler, S. E.; Nestor, M. B. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Carpenter, J. M. [Argonne National Laboratory, Argonne, IL 60439 (United States); Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2013-01-01

    Early neutron diffraction experiments performed in 1944 using the first nuclear reactors are described. Although neutron diffraction was first observed using radioactive decay sources shortly after the discovery of the neutron, it was only with the availability of higher intensity neutron beams from the first nuclear reactors, constructed as part of the Manhattan Project, that systematic investigation of Bragg scattering became possible. Remarkably, at a time when the war effort was singularly focused on the development of the atomic bomb, groups working at Oak Ridge and Chicago carried out key measurements and recognized the future utility of neutron diffraction quite independent of its contributions to the measurement of nuclear cross sections. Ernest O. Wollan, Lyle B. Borst and Walter H. Zinn were all able to observe neutron diffraction in 1944 using the X-10 graphite reactor and the CP-3 heavy water reactor. Subsequent work by Wollan and Clifford G. Shull, who joined Wollan’s group at Oak Ridge in 1946, laid the foundations for widespread application of neutron diffraction as an important research tool.

  8. The early development of neutron diffraction: science in the wings of the Manhattan Project

    International Nuclear Information System (INIS)

    Mason, T. E.; Gawne, T. J.; Nagler, S. E.; Nestor, M. B.; Carpenter, J. M.

    2013-01-01

    Early neutron diffraction experiments performed in 1944 using the first nuclear reactors are described. Although neutron diffraction was first observed using radioactive decay sources shortly after the discovery of the neutron, it was only with the availability of higher intensity neutron beams from the first nuclear reactors, constructed as part of the Manhattan Project, that systematic investigation of Bragg scattering became possible. Remarkably, at a time when the war effort was singularly focused on the development of the atomic bomb, groups working at Oak Ridge and Chicago carried out key measurements and recognized the future utility of neutron diffraction quite independent of its contributions to the measurement of nuclear cross sections. Ernest O. Wollan, Lyle B. Borst and Walter H. Zinn were all able to observe neutron diffraction in 1944 using the X-10 graphite reactor and the CP-3 heavy water reactor. Subsequent work by Wollan and Clifford G. Shull, who joined Wollan’s group at Oak Ridge in 1946, laid the foundations for widespread application of neutron diffraction as an important research tool

  9. Three frequency modulated combination thermal neutron lifetime log and porosity

    International Nuclear Information System (INIS)

    Paap, H.J.; Arnold, D.M.; Smith, M.P.

    1976-01-01

    Methods are disclosed for measuring simultaneously the thermal neutron lifetime of the borehole fluid and earth formations in the vicinity of a well borehole, together with the formation porosity. A harmonically intensity modulated source of fast neutrons is used to irradiate the earth formations with fast neutrons at three different modulation frequencies. Intensity modulated clouds of thermal neutrons at each of the three modulation frequencies are detected by dual spaced detectors and the relative phase shift of the thermal neutrons with respect to the fast neutrons is determined at each of the three modulation frequencies at each detector. These measurements are then combined to determine simultaneously the thermal neutron decay time of the borehole fluid, the thermal neutron decay time of surrounding earth formation media and the porosity of the formation media

  10. Thermal neutron converter for irradiations with fission neutrons

    International Nuclear Information System (INIS)

    Wagner, F.M.; Kampfer, S.; Kastenmuller, A.; Waschkowski, W.; Bucherl, Th.; Kampfer, S.

    2007-01-01

    The new research reactor FRM II at Garching started operation in March 2004. The compact core is cooled by light water, and moderated by heavy water. Two fuel plates mounted in the heavy water tank convert thermal to fast neutrons. The fast neutron flux in the connected beam tube is up to 7 centre dot 10 8 s -1 cm -2 (depending on filters and collimation); the mean neutron energy is about 1.6 MeV. There are two irradiation rooms along the beam. The first is mainly used for medical therapy (MEDAPP facility), the second for materials characterization (NECTAR facility). At the former therapy facility RENT at the old research reactor FRM, the same beam quality was available until July 2000. Therefore, only a small program is run for the determination of the biological effectiveness of the new beam. The neutron and gamma dose rates in the medical beam are 0.54 and 0.20 Gy/min, respectively. The therapy facility MEDAPP is still under examination according to European regulations for medical devices. Full medical operation will start in 2007. The radiography and tomography facility NECTAR is in operation and aims at non-destructive inspection of objects up to 400 kg mass and 80 centre dot 80 centre dot 80 cm 3 in size. As for fission neutrons the macroscopic cross section of hydrogen is much higher than for other materials (e. g. Fe and Pb), one special application is the detection of hydrogen-containing materials (e. g. oil) in dense materials

  11. Incident spectrum determination for time-of-flight neutron powder diffraction data analysis

    International Nuclear Information System (INIS)

    Hodges, J. P.

    1998-01-01

    Accurate characterization of the incident neutron spectrum is an important requirement for precise Rietveld analysis of time-of-flight powder neutron diffraction data. Without an accurate incident spectrum the calculated model for the measured relative intensities of individual Bragg reflections will possess systematic errors. We describe a method for obtaining an accurate numerical incident spectrum using data from a transmitted beam monitor

  12. Proceedings of the 1986 workshop on advanced time-of-flight neutron powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, A.C.; Smith, K. (comps.)

    1986-09-01

    This report contains abstracts of talks and summaries of discussions from a small workshop held to discuss the future of time-of-flight neutron powder diffraction and its implementation at the Los Alamos Neutron Scattering Center. 47 refs., 3 figs.

  13. Application of 2-dimensional coordinate system conversion in stress measurements with neutron diffraction

    International Nuclear Information System (INIS)

    Wang, D.-Q.; Hubbard, C.R.; Spooner, S.

    2000-01-01

    This paper will present a method and program to precisely calculate the coordinates in a positioner coordinate system from given sample position coordinates with a minimum number of neutron surface scans for three possible circumstances in stress and texture measurement using neutron diffraction

  14. Proceedings of the 1986 workshop on advanced time-of-flight neutron powder diffraction

    International Nuclear Information System (INIS)

    Lawson, A.C.; Smith, K.

    1986-09-01

    This report contains abstracts of talks and summaries of discussions from a small workshop held to discuss the future of time-of-flight neutron powder diffraction and its implementation at the Los Alamos Neutron Scattering Center. 47 refs., 3 figs

  15. Influence of multiple small-angle neutron scattering on diffraction peak broadening in ferritic steel

    Czech Academy of Sciences Publication Activity Database

    Woo, W.; Em, V.; Shin, E.; Mikula, Pavol; Ryukhtin, Vasyl

    2015-01-01

    Roč. 48, APR (2015), s. 350-356 ISSN 0021-8898 R&D Projects: GA ČR GB14-36566G; GA MŠk(CZ) LM2011019 Institutional support: RVO:61389005 Keywords : peak broadening * small-angle neutron scattering * neutron diffraction * magnetic domain Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.720, year: 2014

  16. Development of temperature related thermal neutron scattering database for MCNP

    International Nuclear Information System (INIS)

    Mei Longwei; Cai Xiangzhou; Jiang Dazhen; Chen Jingen; Guo Wei

    2013-01-01

    Based on ENDF/B-Ⅶ neutron library, the thermal neutron scattering library S(α, β) for molten salt reactor moderators was developed. The temperatures of this library were chose as the characteristic temperature of the molten salt reactor. The cross section of the thermal neutron scattering of ACE format was investigated, and this library was also validated by the benchmarks of ICSBEP. The uncertainties shown in the validation were in reasonable range when compared with the thermal neutron scattering library tmccs which included in the MCNP data library. It was proved that the thermal neutron scattering library processed in this study could be used in the molten salt reactor design. (authors)

  17. 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.

  18. 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.

  19. Stress measurement by neutron diffraction method. Standard method using angular dispersion method and trial of using neutron IP

    International Nuclear Information System (INIS)

    Sasaki, Toshihiko; Takago, Shigeki

    2016-01-01

    This paper outlined a stress measurement method using neutrons, and introduced the application examples to stress measurement for metal-based composite materials. In the angular dispersion type measurement using a steady-state reactor type neutron source, the white beams taken out from a nuclear reactor are monochromatized (wavelength λ is a constant value) with a single crystal monochromator and utilized. As an example of measurement, there was the case as follows: the stress of a sintered material which has been put to practical use as valve seat part for automobiles was measured by the neutron method, and the deformation behavior during load was studied. This study performed neutron diffraction measurement using a residual stress analyzer (RESA: Diffractometer for Residual Stress Analysis) installed at JAEA's experimental reactor JRR-3. As a result, it was found that the stress state of the sintered composite material of Fe-Cr and TiN can be predicted with a micromechanics model. A neutron diffraction ring can be obtained using a neutron image plate (IP), where fine powder of gadolinium (Gd) was incorporated into IP for X-rays, and it can be used as an IP reader in the same way as the case of X-rays. A report has been introduced on the examination results of the highly accurate stress measurement by applying the cos α method devised for X-ray stress measurement to neutron diffraction ring. (A.O.)

  20. Residual Stresses in DC cast Aluminum Billet: Neutron Diffraction Measurements and Thermomechanical Modeling

    International Nuclear Information System (INIS)

    Drezet, J.-M.; Evans, A.; Pirling, T.

    2011-01-01

    Thermally-induced residual stresses, generated during the industrial Direct Chill casting process of aluminum alloys, can cause both significant safety concerns as well as the formation of defects during down-stream processing. Although these thermally induced strains can be partially relieved by permanent deformation, cracks will be generated either during solidification (hot tears) or post-solidification cooling (cold cracks) when stresses exceed the deformation limit of the alloy. Furthermore, the thermally induced strains result in the presence of large internal stresses within the billet before further processing steps. Although numerical models have been previously developed to compute these residual stresses, most of the computations have been validated only against measured surface distortions. In the present work, the variation in residual elastic strains and stresses in the steady state regime of casting has been measured as a function of radial position using neutron diffraction in an AA6063 grain-refined cylindrical billet. These measurements have been carried out on the same billet section at Poldi at PSI-Villigen and at Salsa at ILL-Grenoble and compare favorably. The results are used to validate a thermo-mechanical finite element casting model and to assess the level of stored elastic energy within the billet.

  1. Neutron irradiated uranium silicides studied by neutron diffraction and Rietveld analysis

    International Nuclear Information System (INIS)

    Birtcher, R.C.; Mueller, M.H.; Richardson, J.W. Jr.; Faber, J. Jr.

    1989-11-01

    Uranium silicides have been considered for use as reactor fuels in both high power and low enrichment applications. However, U 3 Si was found to become amorphous under irradiation and to become mechanically unstable to rapid growth by plastic flow. U 2 Si 2 appears to be stable against amorphization at low displacement rates, but the extent of this stability is uncertain. Although the mechanisms responsible for plastic flow in U 3 Si and other amorphous systems are unknown, as is the importance of crystal structure for amorphization, it may not be surprising that these materials amorphize, in light of the fact that many radioactive nuclide - containing minerals are known to metaminctize (lose crystallinity) under irradiation. The present experiment follows the detailed changes in the crystal structures of U 3 Si and U 3 Si 2 introduced by neutron bombardment and subsequent uranium fission at room temperature. U-Si seems the ideal system for a neutron diffraction investigation since the crystallographic and amorphous forms can be studied simultaneously by combining conventional Rietveld refinement of the crystallographic phases with Fourier-filtering of the non-crystalline scattering component

  2. Bainitic transformation behavior studied by simultaneous neutron diffraction and dilatometric measurement

    International Nuclear Information System (INIS)

    Koo, Minseo; Xu, Pingguang; Tomota, Yo; Suzuki, Hiroshi

    2009-01-01

    Bainitic transformation behavior has firstly been observed using in situ neutron diffraction with an angular dispersive method for a hard bainite steel. The dilatometric measurement was carried out simultaneously with the neutron experiment where changes in (1 1 1) austenite and (1 1 0) ferrite diffraction profiles were monitored during heating, cooling and holding at a transformation temperature. The neutron experiments results agree with dilatometry results. They appear to have found that the austenite peak broadening occurs after the onset of bainitic transformation but not before.

  3. 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...

  4. A study on the utilization of hyper-thermal neutrons for neutron capture therapy

    International Nuclear Information System (INIS)

    Sakurai, Yoshinori; Kobayashi, Tooru; Kanda, Keiji

    1993-01-01

    The utilization of hyper-thermal neutrons, which have an energy spectrum of a Maxwellian distribution of a higher temperature than the room temperature of 300 K, was studied in order to improve the thermal neutron flux distribution at the deeper part in a living body for neutron capture therapy. Simulation calculations were carried out using MCNP-V3 in order to confirm the characteristics of hyper-thermal neutrons, i.e., (1) depth dependence of neutron energy spectrum, and (2) depth distribution of the reaction rate in a water phantom for materials with 1/v neutron absorption. It is confirmed that the hyper-thermal neutron irradiation can improve the thermal neutron flux distribution in the deeper and wider area in a living body compared with the thermal neutron irradiation. Practically, by the incidence of the hyper-thermal neutrons with a 3000 K Maxwellian distribution, the thermal neutron flux at 5 cm depth can be given about four times larger than by the incidence of the thermal neutrons of 300 K. (author)

  5. Ultra-low-temperature neutron diffraction. Final report, July 1, 1983-June 30, 1985. Final report

    International Nuclear Information System (INIS)

    Halperin, W.P.; Ketterson, J.B.

    1985-07-01

    An ultra-low-temperature neutron diffraction facility has been constructed at Argonne National Laboratory. The initial and primary purpose of this facility is to study nuclear magnetic ordering phenomenon. Magnetic structure information is commonly recognized as being fundamental to the progress in theoretical and experimental efforts in the field of magnetism. We have initiated study of the nuclear spin in solid 3 He and in metals. In 3 He the nuclear spins order at 1.1 mK. Structure information for neutron diffraction would contribute significantly to this problem of nuclear magnetism. Despite substantial experimental difficulties, careful evaluation suggests that examination of the nuclear structure in this unique quantum crystal is indeed feasible by neutron diffraction. Substantial progress has been made in growing single crystals of 3 He and establishing its temperature in the presence of a neutron flux. We have also initiated investigation of nuclear ordering in copper and PrCu 6

  6. Activation measurements for thermal neutrons. Part J. Evaluation of thermal neutron transmission factors

    International Nuclear Information System (INIS)

    Egbert, Stephen D.

    2005-01-01

    In order to relate thermal neutron activation measurements in samples to the calculated free-in-air thermal neutron activation levels given in Chapter 3, use is made of sample transmission factors. Transmission factors account for the modification of the fluence and activation at each sample's in situ location. For the purposes of this discussion, the transmission factor (TF) is defined as the ratio of the in situ sample activation divided by the free-in-air (FIA) activation at a height of 1 m above ground at the same ground range. The procedures for calculation of TF's and example results are presented in this section. (author)

  7. maximum neutron flux at thermal nuclear reactors

    International Nuclear Information System (INIS)

    Strugar, P.

    1968-10-01

    Since actual research reactors are technically complicated and expensive facilities it is important to achieve savings by appropriate reactor lattice configurations. There is a number of papers, and practical examples of reactors with central reflector, dealing with spatial distribution of fuel elements which would result in higher neutron flux. Common disadvantage of all the solutions is that the choice of best solution is done starting from the anticipated spatial distributions of fuel elements. The weakness of these approaches is lack of defined optimization criteria. Direct approach is defined as follows: determine the spatial distribution of fuel concentration starting from the condition of maximum neutron flux by fulfilling the thermal constraints. Thus the problem of determining the maximum neutron flux is solving a variational problem which is beyond the possibilities of classical variational calculation. This variational problem has been successfully solved by applying the maximum principle of Pontrjagin. Optimum distribution of fuel concentration was obtained in explicit analytical form. Thus, spatial distribution of the neutron flux and critical dimensions of quite complex reactor system are calculated in a relatively simple way. In addition to the fact that the results are innovative this approach is interesting because of the optimization procedure itself [sr

  8. FEM Analysis and Measurement of Residual Stress by Neutron Diffraction on the Dissimilar Overlay Weld Pipe

    International Nuclear Information System (INIS)

    Kim, Kang Soo; Lee, Ho Jin; Woo, Wan Chuck; Seong, Baek Seok; Byeon, Jin Gwi; Park, Kwang Soo; Jung, In Chul

    2010-01-01

    Much research has been done to estimate the residual stress on a dissimilar metal weld. There are many methods to estimate the weld residual stress and FEM (Finite Element Method) is generally used due to the advantage of the parametric study. And the X-ray method and a Hole Drilling technique for an experimental method are also usually used. The aim of this paper is to develop the appropriate FEM model to estimate the residual stresses of the dissimilar overlay weld pipe. For this, firstly, the specimen of the dissimilar overlay weld pipe was manufactured. The SA 508 Gr3 nozzle, the SA 182 safe end and SA376 pipe were welded by the Alloy 182. And the overlay weld by the Alloy 52M was performed. The residual stress of this specimen was measured by using the Neutron Diffraction device in the HANARO (High-flux Advanced Neutron Application ReactOr) research reactor, KAERI (Korea Atomic Energy Research Institute). Secondly, FEM Model on the dissimilar overlay weld pipe was made and analyzed by the ABAQUS Code (ABAQUS, 2004). Thermal analysis and stress analysis were performed, and the residual stress was calculated. Thirdly, the results of the FEM analysis were compared with those of the experimental methods

  9. X-ray and neutron diffraction study of alums. Pt. 2 and 3

    International Nuclear Information System (INIS)

    Abdeen, A.M.; Will, G.; Schaefer, W.; Kirfel, A.; Bargouth, M.O.; Recker, K.; Weiss, A.

    1981-01-01

    The crystal structure of the alums, (NH 3 CH 3 )Al(SO 4 ) 2 x 12 H 2 0 and (NH 4 )AL(SO 4 ) 2 x 12 H 2 0, has been determined and refined from X-ray and neutron diffraction data. The compounds crystallize cubic in space group Pa3 (Z = 4). The positional and thermal parameters of all atoms including hydrogens have been refined by full matrix least-sqares analysis resulting in Rsub(w) values from the X-ray and neutron data of 0.030 and 0.029 respectively for the methylammonium alum and of 0.024 and 0.014 respectively for the ammonium alum. The atoms of the cation groups (NH 3 CH 3 ) + and (NH 4 ) + are distributed on 8(c) and 24(d) positions in two orientations of equal probability on and around the [111] direction related to each other by an inversion centre. The disorder in the cation groups is explained by a quantized rotation. Disorder in the sulfate groups has been determined to 4.2% for the methylammonium alum and to about 17% for the ammonium alum. The disordered sulfate tetrahedra are distorted and in a reversed orientation along the threefold axis. The system of the hydrogen bonds is discussed. (orig.)

  10. 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

  11. Novel Experimental Setups for In Situ Neutron Diffraction

    DEFF Research Database (Denmark)

    Ahlburg, Jakob; H. Gjørup, Frederik; Mørch, Mathias

    Modern synchrotron and neutron sources provide the intensities needed for performing never-before-seen experiments. With the imminent launch of the scattering facilities MAX IV & ESS, it is interesting to explore novel setups that enable new experiments at these sites. X-ray and neutron technique...... also provide information on the magnetic structure and can probe large bulk samples, allowing the study of compacted powders for use in permanent magnets....

  12. Residual Stress Measurement of SiC tile/Al7075 Hybrid Composites by Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Bok; Lee, Jun Ho; Hong, Soon Hyung; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of); Lee, Sang Bok; Lee, Sang Kwan [Korea Institute of Materials Science, Changwon (Korea, Republic of); Muslihd, M. Rifai [Center for Advanced Materials Science and Technology, Tangerang (India)

    2016-05-15

    In this research, SiC which has low density, high compressive strength, and high elastic modulus was used to fabricate the armor plate. In addition, Al which has low density and high toughness was used for a metal matrix of the composites. If two materials are combined, the composite can be effective materials for light weight armor applications. However, the existence of a large difference in coefficients of thermal expansion (CTE) between SiC and Al matrix, SiC/Al composites can have residual stresses while cooled in the fabrication process. Previous research reported that residual stresses in the composites or microstructures have an effect on the fatigue life and their mechanical properties. Some researchers reported about the residual stresses in the SiCp/Al metal matrix composites by numerical simulation systems, X-ray diffraction, and destructive methods. In order to analyze the residual stress of SiC/Al composites, the neutron diffraction as the non-destructive method was performed in this research. The 50 vol.% SiC{sub p}/Al7075 composites and SiC tile inserted 50 vol.% SiC{sub p}/Al7075 hybrid composites were measured to analyze the residual stress of Al (111) and SiC (111). Both samples had the tensile residual stresses in the Al (111) and the compressive residual stresses in the SiC (111) due to the difference in CTE.

  13. The measurements of thermal neutron flux distribution in a paraffin

    Indian Academy of Sciences (India)

    The term `thermal flux' implies a Maxwellian distribution of velocity and energy corresponding to the most probable velocity of 2200 ms-1 at 293.4 K. In order to measure the thermal neutron flux density, the foil activation method was used. Thermal neutron flux determination in paraffin phantom by counting the emitted rays of ...

  14. Texture investigation in aluminium and iron - silicon samples by neutron diffraction technique

    International Nuclear Information System (INIS)

    Pugliese, R.; Yamasaki, J.M.

    1988-09-01

    By means of the neutron diffraction technique the texture of 5% and 98% rolled-aluminium and of iron-silicon steel used in the core of electric transformers, have been determined. The measurements were performed by using a neutron diffractometer installed at the IEA-R1 Nuclear Research Reactor, in the Beam-Hole n 0 . 6. To avoid corrections such as neutron absorption and sample luminosity the geometric form of the samples were approximated to spheric or octagonal prism, and its dimensions do not exceed that of the neutron beam. The texture of the samples were analysed with the help of a computer programme that analyses the intensity of the diffracted neutron beam and plot the pole figures. (author) [pt

  15. The internal stress measurement the neutron diffraction bring happiness to your country

    Energy Technology Data Exchange (ETDEWEB)

    Minakawa, Nobuaki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The neutron was discovered by Chadwick in 1932. The first reactor was constructed by the USA in 1942. After that, the research and development of reactors advanced. Numbers of reactors were constructed in Europe and in the US. The researches, which use the neutron, were performed actively and excellent results were obtained in wide fields. The penetrating power of the neutron and the neutron diffraction method began to attract attention for the application to the internal stress measurement, too. In Japan, the neutron diffractometer for the residual stress measurement exclusive was installed in the JRR-3M research reactor of JAERI in 1992, and the research was started. At present, we are using it for the stress measurements of the parts of aircrafts, railways, automobiles, buildings, machines, home electronics products and so on including nuclear reactors. Reliable science must be introduced in order to support safety and long life operation and to supply them at reasonable cost. Among the various scientific probes to find faults in materials, diffraction technique is used to measure the strain distribution in materials by observing the local changes of the distance between crystallographic planes and the stress distribution is computed to improve manufacturing processes. It is only neutron diffraction that can be used to measure the strain inside the materials. Here, I present an overview of the utilization of neutron scattering research for the industrial uses and the history of the neutron scattering research in JAERI briefly. (J.P.N.)

  16. The internal stress measurement the neutron diffraction will bring happiness to your country

    International Nuclear Information System (INIS)

    Minakawa, Nobuaki

    2003-01-01

    The neutron was discovered by Chadwick in 1932. The first reactor was constructed by the USA in 1942. After that, the research and development of reactors advanced. Numbers of reactors were constructed in Europe and in the US. The researches, which use the neutron, were performed actively and excellent results were obtained in wide fields. The penetrating power of the neutron and the neutron diffraction method began to attract attention for the application to the internal stress measurement, too. In Japan, the neutron diffractometer for the residual stress measurement exclusive was installed in the JRR-3M research reactor of JAERI in 1992, and the research was started. At present, we are using it for the stress measurements of the parts of air crafts, railways, automobiles, buildings, machines, home electronics products and so on including nuclear reactors. Reliable science must be introduced in order to support safety and long life operation and to supply them at reasonable cost. Among the various scientific probes to find faults in materials, diffraction technique is used to measure the strain distribution in materials by observing the local changes of the distance between crystallographic planes and the stress distribution is computed to improve manufacturing processes. It is only neutron diffraction that can be used to measure the strain inside the materials. Here, I present an overview of the utilization of neutron scattering research for the industrial uses and the history of the neutron scattering research in JAERI briefly. (J.P.N.)

  17. Analytic scattering kernels for neutron thermalization studies

    International Nuclear Information System (INIS)

    Sears, V.F.

    1990-01-01

    Current plans call for the inclusion of a liquid hydrogen or deuterium cold source in the NRU replacement vessel. This report is part of an ongoing study of neutron thermalization in such a cold source. Here, we develop a simple analytical model for the scattering kernel of monatomic and diatomic liquids. We also present the results of extensive numerical calculations based on this model for liquid hydrogen, liquid deuterium, and mixtures of the two. These calculations demonstrate the dependence of the scattering kernel on the incident and scattered-neutron energies, the behavior near rotational thresholds, the dependence on the centre-of-mass pair correlations, the dependence on the ortho concentration, and the dependence on the deuterium concentration in H 2 /D 2 mixtures. The total scattering cross sections are also calculated and compared with available experimental results

  18. Maximum neutron flux in thermal reactors

    International Nuclear Information System (INIS)

    Strugar, P.V.

    1968-12-01

    Direct approach to the problem is to calculate spatial distribution of fuel concentration if the reactor core directly using the condition of maximum neutron flux and comply with thermal limitations. This paper proved that the problem can be solved by applying the variational calculus, i.e. by using the maximum principle of Pontryagin. Mathematical model of reactor core is based on the two-group neutron diffusion theory with some simplifications which make it appropriate from maximum principle point of view. Here applied theory of maximum principle are suitable for application. The solution of optimum distribution of fuel concentration in the reactor core is obtained in explicit analytical form. The reactor critical dimensions are roots of a system of nonlinear equations and verification of optimum conditions can be done only for specific examples

  19. X-ray diffraction patterns of thermally-reduced graphenes

    International Nuclear Information System (INIS)

    Ju, Hae-Mi; Choi, Sung-Ho; Huh, Seung-Hun

    2010-01-01

    Thermally-reduced graphenes (GPs) from graphene oxides (GOs) in the range of 200 - 800 .deg. C have been investigated by using X-ray diffraction (XRD). The temperature-dependent evolutions of the (002) peaks show that exfoliation of GO sheets occurs, along with wrinkling, at ∼200 .deg. C and that high-quality GPs are produced at ∼ 600 .deg. C (GP 600 ). These phenomena are explained by the vaporization of intercalated water molecules and the effective removal of the oxide groups of GO by thermal annealing, respectively. GP 600 exhibited a clean and sharp (002) peak corresponding to an interlayer distance of 3.392 A, which is close to that of conventional graphene (∼3.4 A). The structure of GP 600 is further discussed.

  20. Studying magnetic structure of Bi doped Co2MnO4 cubic spinel by neutron diffraction

    International Nuclear Information System (INIS)

    Rajeevan, N.E.; Kaushik, S.D.; Kumar, Ravi

    2016-01-01

    In present work, we studied effect of Bi doped spinel Bi x Co 2-x MnO 4 (x = 0, 0.05, 0.10, 0.15 and 0.20) samples on their crystal as well as magnetic structure by employing neutron diffraction of wavelength 1.48 A using focusing crystal diffractometer of UGC-DAECSR Mumbai Centre at Dhruva, Trombay, Mumbai, India. The analysis of the neutron diffraction using Fullprof program reveals that crystal structure due to Bi doping remains intact and all the samples have been formed in the cubic spinel structure with Fd3m (space group no. 227). The lattice parameter shows the positive thermal expansion upon Bi doping across the temperature range. In order to understand the implication on the spin structure and magnetism in the detail, temperature dependent neutron diffraction study is carried out on some of the samples (x = 0, 0.1) in the series. The ND pattern of x = 0.1 at 2.9K is shown. The experimental finding in terms of modified magnetic structure upon Bi doping are discussed which are understood in terms of variation in the ferroelectric properties, bond lengths and their effect on the CoO 6 polyhedra. Furthermore, Bi substitution in Co 2 MnO 4 spinel brings in the balance of structural distortion, which affects both ferrimagnetism and ferroelectricity

  1. Residual stress distribution in carbon steel pipe welded joint measured by neutron diffraction

    International Nuclear Information System (INIS)

    Hayashi, Makoto; Ishiwata, Masayuki; Morii, Yukio; Minakawa, Nobuaki

    2000-01-01

    In order to estimate crack growth behavior of fatigue and stress corrosion cracking in pipes, the residual stress distribution near the pipe weld region has to be measured through the wall thickness. Since the penetration depth of neutron is deep enough to pass through the thick pipe wall, the neutron diffraction technique for the residual stress measurement is effective for this purpose. At the first step the residual stress distribution near the weld region in a butt-welded carbon steel pipe was measured by the neutron diffraction. Significant stresses extended only to a distance of 30 mm from the center of the weld. The major tensile stresses occurred in the hoop direction in the fusion and heat affected zones of the weldment, and they attained a level greater than 200 MPa through the thickness. While the axial residual stress at the inside surface was 50 MPa, the stress at the outside surface was -100 MPa. The comparison of residual stress distributions measured by the neutron diffraction, the X-ray diffraction and the strain gauge method reveals that the neutron diffraction is the most effective for measuring the residual stress inside the structural components. (author)

  2. Neutron and X-ray diffraction from modulated structures

    International Nuclear Information System (INIS)

    Harris, P.

    1994-07-01

    This thesis describes X-ray and neutron scattering experiments performed on two examples of modulated structures. After an introduction to the subject of modulated structures, the thesis is divided in three parts. A single crystal elastic neutron scattering experiment between 4.2 and 115 Κ has been performed and four-circle X-ray data have been collected at 8 Κ for the monoclinic low-temperature phase of the layered perovskite PAMC. The results from the neutron scattering experiment indicate that magnetoelastic effects influence the ordering of the crystal. The X-ray experiments have made it possible to determine the crystal structure in the low-temperature phase. The superspace group is P2 1 /b(β-30)Os, with β = 1/3. A small-angle neutron scattering experiment has been performed on the magnetic structure of manganese silicide. When a magnetic field is applied, the modulation vectors turn towards the field direction, showing domain growth and diverging peak widths as they approach the field direction. Phase 'A' is established to have the modulation vectors directed perpendicular to the field direction. Cooling in zero field shows increasing peak widths at low temperatures, indicating a lock-in transition below the lowest reached temperature. To be able to analyse the data of the magnetic order in MnSi, and analytical calculation of the three dimensional resolution function for a small-angle neutron scattering spectrometer has been performed. The calculation is done by application of a combination of phase space analysis and Gaussian approximations for the neutron distribution as well as for the transmission functions of the different apertures. A finite mosaic spread of the crystal and finite correlation widths of the Bragg reflections have been included in the cross section. (au) (3 tabs., 48 ills., 100 refs.)

  3. A preliminary neutron diffraction study of rasburicase, a recombinant urate oxidase enzyme, complexed with 8-azaxanthin

    Energy Technology Data Exchange (ETDEWEB)

    Budayova-Spano, Monika, E-mail: spano@embl-grenoble.fr [European Molecular Biology Laboratory Grenoble Outstation, 6 Rue Jules Horowitz, 38042 Grenoble (France); Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble (France); Bonneté, Françoise; Ferté, Natalie [Centre de Recherche en Matière Condensée et Nanosciences, Campus de Luminy, Case 913, 13288 Marseille (France); El Hajji, Mohamed [Sanofi-Aventis, 371 Rue du Professeur Blayac, 34184 Montpellier (France); Meilleur, Flora [Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble (France); Blakeley, Matthew Paul [European Molecular Biology Laboratory Grenoble Outstation, 6 Rue Jules Horowitz, 38042 Grenoble (France); Castro, Bertrand [Sanofi-Aventis, 371 Rue du Professeur Blayac, 34184 Montpellier (France); European Molecular Biology Laboratory Grenoble Outstation, 6 Rue Jules Horowitz, 38042 Grenoble (France)

    2006-03-01

    Neutron diffraction data of hydrogenated recombinant urate oxidase enzyme (Rasburicase), complexed with a purine-type inhibitor 8-azaxanthin, was collected to 2.1 Å resolution from a crystal grown in D{sub 2}O by careful control and optimization of crystallization conditions via knowledge of the phase diagram. Deuterium atoms were clearly seen in the neutron-scattering density map. Crystallization and preliminary neutron diffraction measurements of rasburicase, a recombinant urate oxidase enzyme expressed by a genetically modified Saccharomyces cerevisiae strain, complexed with a purine-type inhibitor (8-azaxanthin) are reported. Neutron Laue diffraction data were collected to 2.1 Å resolution using the LADI instrument from a crystal (grown in D{sub 2}O) with volume 1.8 mm{sup 3}. The aim of this neutron diffraction study is to determine the protonation states of the inhibitor and residues within the active site. This will lead to improved comprehension of the enzymatic mechanism of this important enzyme, which is used as a protein drug to reduce toxic uric acid accumulation during chemotherapy. This paper illustrates the high quality of the neutron diffraction data collected, which are suitable for high-resolution structural analysis. In comparison with other neutron protein crystallography studies to date in which a hydrogenated protein has been used, the volume of the crystal was relatively small and yet the data still extend to high resolution. Furthermore, urate oxidase has one of the largest primitive unit-cell volumes (space group I222, unit-cell parameters a = 80, b = 96, c = 106 Å) and molecular weights (135 kDa for the homotetramer) so far successfully studied with neutrons.

  4. Fluid bilayer structure determination: Joint refinement in composition space using X-ray and neutron diffraction data

    Energy Technology Data Exchange (ETDEWEB)

    White, S.H. [Univ. of California, Irvine, CA (United States); Wiener, M.C. [Univ. of California, San Francisco, CA (United States)

    1994-12-31

    Experimentally-determined structural models of fluid lipid bilayers are essential for verifying molecular dynamics simulations of bilayers and for understanding the structural consequences of peptide interactions. The extreme thermal motion of bilayers precludes the possibility of atomic-level structural models. Defining {open_quote}the structure{close_quote} of a bilayer as the time-averaged transbilayer distribution of the water and the principal lipid structural groups such as the carbonyls and double-bonds (quasimolecular fragments), one can represent the bilayer structure as a sum of Gaussian functions referred to collectively as the quasimolecular structure. One method of determining the structure is by neutron diffraction combined with exhaustive specific deuteration. This method is impractical because of the expense of the chemical syntheses and the limited amount of neutron beam time currently available. We have therefore developed the composition space refinement method for combining X-ray and minimal neutron diffraction data to arrive at remarkably detailed and accurate structures of fluid bilayers. The composition space representation of the bilayer describes the probability of occupancy per unit length across the width of the bilayer of each quasimolecular component and permits the joint refinement of X-ray and neutron lamellar diffraction data by means of a single quasimolecular structure that is fitted simultaneously to both data sets. Scaling of each component by the appropriate neutron or X-ray scattering length maps the composition-space profile to the appropriate scattering length space for comparison to experimental data. The difficulty with the method is that fluid bilayer structures are generally only marginally determined by the experimental data. This means that the space of possible solutions must be extensively explored in conjunction with a thorough analysis of errors.

  5. Fluid bilayer structure determination: Joint refinement in composition space using X-ray and neutron diffraction data

    International Nuclear Information System (INIS)

    White, S.H.; Wiener, M.C.

    1994-01-01

    Experimentally-determined structural models of fluid lipid bilayers are essential for verifying molecular dynamics simulations of bilayers and for understanding the structural consequences of peptide interactions. The extreme thermal motion of bilayers precludes the possibility of atomic-level structural models. Defining open-quote the structure close-quote of a bilayer as the time-averaged transbilayer distribution of the water and the principal lipid structural groups such as the carbonyls and double-bonds (quasimolecular fragments), one can represent the bilayer structure as a sum of Gaussian functions referred to collectively as the quasimolecular structure. One method of determining the structure is by neutron diffraction combined with exhaustive specific deuteration. This method is impractical because of the expense of the chemical syntheses and the limited amount of neutron beam time currently available. We have therefore developed the composition space refinement method for combining X-ray and minimal neutron diffraction data to arrive at remarkably detailed and accurate structures of fluid bilayers. The composition space representation of the bilayer describes the probability of occupancy per unit length across the width of the bilayer of each quasimolecular component and permits the joint refinement of X-ray and neutron lamellar diffraction data by means of a single quasimolecular structure that is fitted simultaneously to both data sets. Scaling of each component by the appropriate neutron or X-ray scattering length maps the composition-space profile to the appropriate scattering length space for comparison to experimental data. The difficulty with the method is that fluid bilayer structures are generally only marginally determined by the experimental data. This means that the space of possible solutions must be extensively explored in conjunction with a thorough analysis of errors

  6. Thermalization of monoenergetic neutrons in a concrete room

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R.; Manzanares A, E.; Hernandez D, V.M.; Mercado, G.A. [UAZ, A.P. 336, 98000 Zacatecas (Mexico); Iniguez, M.P.; Martin M, A. [Universidad de Valladolid, (Spain)

    2006-07-01

    The thermalization of neutrons from monoenergetic neutron sources in a concrete room has been studied. During calibration of neutron detectors it is mandatory to make corrections due to neutron scattering produced by the room walls, therefore this factor must be known in advance. The scattered neutrons are thermalized and produce a neutron field that is directly proportional to source strength and inversely proportional to room total wall-surfaces, the proportional coefficient has been calculated for neutrons whose energy goes from 1 eV to 20 MeV. This coefficient was calculated using Monte Carlo methods for 150, 200 and 300 cm-radius spherical cavity, where monoenergetic neutrons were located at the center, along the spherical cavity radius neutron spectra were calculated at several source-to-detector distances inside the cavity. The obtained coefficient is almost three times larger than the factor normally utilized. (Author)

  7. Thermal neutron capture gamma-rays

    International Nuclear Information System (INIS)

    Tuli, J.K.

    1983-01-01

    The energy and intensity of gamma rays as seen in thermal neutron capture are presented. Only those (n,α), E = thermal, reactions for which the residual nucleus mass number is greater than or equal to 45 are included. These correspond to evaluations published in Nuclear Data Sheets. The publication source data are contained in the Evaluated Nuclear Structure Data File (ENSDF). The data presented here do not involve any additional evaluation. Appendix I lists all the residual nuclides for which the data are included here. Appendix II gives a cumulated index to A-chain evaluations including the year of publication. The capture gamma ray data are given in two tables - the Table 1 is the list of all gamma rays seen in (n,#betta#) reaction given in the order of increasing energy; the Table II lists the gamma rays according to the nuclide

  8. Study of FeC1{sub 2} by neutron diffraction; Etude de Fe C1{sub 2} par diffraction de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Herpin, A; Meriel, P [Commissariat a l' Energie Atomique, Saclay (France)

    1959-07-01

    Magnetic measurements have shown that anhydrous ferrous chloride behaves as a metamagnetic at temperatures below 24 deg. K, in other words as an antiferromagnetic sensitive to the action of an external field of moderate strength. The aim of the neutron diffraction study is to determine precisely the arrangement of the magnetic moments, and to follow its evolution as a function of the applied field. (author) [French] Des mesures magnetiques ont montre que le chlorure ferreux anhydre se comporte comme un metamagnetique a une temperature inferieure a 24 deg. K, c'est a dire comme un antiferromagnetique sensible a l'action d'un champ exterieur modere. L'etude par diffraction de neutrons a pour buts de preciser la disposition des moments magnetiques et de suivre son evolution en fonction du champ applique. (auteur)

  9. Study of FeC1{sub 2} by neutron diffraction; Etude de Fe C1{sub 2} par diffraction de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Herpin, A.; Meriel, P. [Commissariat a l' Energie Atomique, Saclay (France)

    1959-07-01

    Magnetic measurements have shown that anhydrous ferrous chloride behaves as a metamagnetic at temperatures below 24 deg. K, in other words as an antiferromagnetic sensitive to the action of an external field of moderate strength. The aim of the neutron diffraction study is to determine precisely the arrangement of the magnetic moments, and to follow its evolution as a function of the applied field. (author) [French] Des mesures magnetiques ont montre que le chlorure ferreux anhydre se comporte comme un metamagnetique a une temperature inferieure a 24 deg. K, c'est a dire comme un antiferromagnetique sensible a l'action d'un champ exterieur modere. L'etude par diffraction de neutrons a pour buts de preciser la disposition des moments magnetiques et de suivre son evolution en fonction du champ applique. (auteur)

  10. Refractive and diffractive neutron optics with reduced chromatic aberration

    DEFF Research Database (Denmark)

    Poulsen, Stefan Othmar; Poulsen, Henning Friis; Bentley, P.M.

    2014-01-01

    by the use of optics for focusing and imaging. Refractive and diffractive optical elements, e.g. compound refractive lenses and Fresnel zone plates, are attractive due to their low cost, and simple alignment. These optical elements, however, suffer from chromatic aberration, which limit their effectiveness...

  11. More accurate thermal neutron coincidence counting technique

    International Nuclear Information System (INIS)

    Baron, N.

    1978-01-01

    Using passive thermal neutron coincidence counting techniques, the accuracy of nondestructive assays of fertile material can be improved significantly using a two-ring detector. It was shown how the use of a function of the coincidence count rate ring-ratio can provide a detector response rate that is independent of variations in neutron detection efficiency caused by varying sample moderation. Furthermore, the correction for multiplication caused by SF- and (α,n)-neutrons is shown to be separable into the product of a function of the effective mass of 240 Pu (plutonium correction) and a function of the (α,n) reaction probability (matrix correction). The matrix correction is described by a function of the singles count rate ring-ratio. This correction factor is empirically observed to be identical for any combination of PuO 2 powder and matrix materials SiO 2 and MgO because of the similar relation of the (α,n)-Q value and (α,n)-reaction cross section among these matrix nuclei. However the matrix correction expression is expected to be different for matrix materials such as Na, Al, and/or Li. Nevertheless, it should be recognized that for comparison measurements among samples of similar matrix content, it is expected that some function of the singles count rate ring-ratio can be defined to account for variations in the matrix correction due to differences in the intimacy of mixture among the samples. Furthermore the magnitude of this singles count rate ring-ratio serves to identify the contaminant generating the (α,n)-neutrons. Such information is useful in process control

  12. Analysis of neutron diffraction peak broadening caused by internal stresses in composite materials

    International Nuclear Information System (INIS)

    Todd, R.I.; Borsa, C.; Derby, B.

    1994-01-01

    Neutron diffraction is an essential tool in the study of internal stresses in composite materials. In most work only the peak shifts caused by the related elastic strains are considered, but other valuable information exists in the form of peak shape changes. The conditions under which the pure diffraction profile of the composite (i.e. the profile when all sources of broadening not caused by the residual stresses are removed) represents the probability distribution of the peak shifts corresponding to the strains are examined. It is shown that in these conditions, the pure diffraction profile has no attributes of particle size broadening (and vice versa), thereby providing a test for the validity of results interpreted in this way. The experimental derivation of measured strain distributions in Al 2 O 3 /SiCp composites using neutron diffraction is described. No apparent particle size broadening was detected, demonstrating the validity of the results, which also satisfied other tests for consistency

  13. Performance of novel moderator for pulsed neutron diffraction

    International Nuclear Information System (INIS)

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

    1991-01-01

    Measurements of neutron pulse time-width and intensity have been carried out on grids of small moderators placed side by side and decoupled by cadmium strips. This moderator concept had been introduced at ICANS-10. The present measurements explore greater moderator thicknesses than those previously attained, yielding information on thickness optimization, while confirming the previous results on resolution which make this moderator a favourable choice in front of the conventional sandwich set-up. (author)

  14. Through-thickness Residual Stress Measurement by Neutron Diffraction in Cu+W Plasma Spray Coatings

    Czech Academy of Sciences Publication Activity Database

    Luzin, V.; Matějíček, Jiří; Gnäupel-Herold, T.

    2010-01-01

    Roč. 652, č. 652 (2010), s. 50-56 ISSN 1662-9752. [International Conference on Mechanical Stress Evaluation by Neutrons and Synchrotron Radiation/5th./. Mito, 10.11.2009-12.11.2009] R&D Projects: GA MŠk ME 901 Institutional research plan: CEZ:AV0Z20430508 Keywords : fusion materials * plasma sprayed coatings * residual stress * neutron diffraction Subject RIV: JG - Metallurgy http://www.scientific.net/MSF.652.50

  15. The use of pulsed neutron diffraction to measure strain in composites

    International Nuclear Information System (INIS)

    Bourke, M.A.M.; Goldstone, J.A.; Shi, N.; Gray, G.T. III; James, M.R.

    1994-01-01

    Neutron diffraction is a technique for measuring strain in crystalline materials. It is non destructive, phase discriminatory and more penetrating than X rays. Pulsed neutron sources (in contrast with steady state reactor sources) are particularly appropriate for examining heterogeneous materials or for recording the polycrystalline response of all lattice reflections. Several different aspects of composite behavior can be characterized and examples are given of residual strain measurements, strain relaxation during heating, applied loading, and determination of the strain distribution function

  16. Time-of-Flight Three Dimensional Neutron Diffraction in Transmission Mode for Mapping Crystal Grain Structures

    DEFF Research Database (Denmark)

    Cereser, Alberto; Strobl, Markus; Hall, Stephen A.

    2017-01-01

    constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF 3DND). Compared to existing analogous X-ray diffraction techniques, ToF 3DND......-of-flight neutron beamline. The technique was developed and tested with data collected at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Complex (J-PARC) for an iron sample. We successfully reconstructed the shape of 108 grains and developed an indexing procedure...

  17. Locations of oxygen, nitrogen and carbon atoms in vanadium determined by neutron diffraction

    International Nuclear Information System (INIS)

    Hiraga, K.; Onozuka, T.; Hirabayashi, M.

    1977-01-01

    The occupation sites of oxygen, nitrogen, and carbon atoms dissolved interstitially in vanadium have been determined by means of neutron diffraction with use of single crystals of VOsub(0.032), VNsub(0.013) and VCsub(0.006). It is revealed that the interstitial atoms occupy, randomly, the octahedral sites in the b.c.c. host lattice of the three crystals. Neutron diffraction is advantageous for the present purpose, since the coherent scattering amplitudes of the solute atoms are much larger than that of the vanadium atom. (Auth.)

  18. Molecular structure and correlations in liquid D-2-propanol through neutron diffraction

    International Nuclear Information System (INIS)

    Sahoo, A.; Sarkar, S.; Joarder, R.N.; Krishna, P.S.R.

    2003-01-01

    Like t-butanol, 2-propanol molecules are quite big with substantial amount of asymmetry in the structure and so the analysis of the neutron diffraction data is tricky. A modified method of analysis, similar to one for liquid t-butanol, enables extraction of the detailed molecular conformation and intermolecular correlations through neutron diffraction. The pre-peak in the structure function, a signature of chain molecular association together with partially identified inter-molecular correlations yield some information about the nature of possible H-bonded molecular clusters in the liquid state. (author)

  19. ATALANTA: a multicomponent pulsed neutron diffraction analysis code

    International Nuclear Information System (INIS)

    Benham, M.J.; Ross, D.K.

    1986-01-01

    The analysis of powder diffraction patterns from metal hydrogen systems present certain problems which have been addressed in a restructured profile analysis program. The heart of this program, ATALANTA, is a routine which locates and processes small sections of the data field to which a minimal number of Bragg peaks contribute intensity. The analysis of a three component test data set is presented in order to demonstrate the method. (author)

  20. Real-time thermal neutron radiographic detection systems

    International Nuclear Information System (INIS)

    Berger, H.; Bracher, D.A.

    1976-01-01

    Systems for real-time detection of thermal neutron images are reviewed. Characteristics of one system are presented; the data include contrast, resolution and speed of response over the thermal neutron intensity range 2.5 10 3 n/cm 2 -sec to 10 7 n/cm 2 -sec

  1. Magneto–Thermal Evolution of Neutron Stars with Emphasis to ...

    Indian Academy of Sciences (India)

    The magnetic and thermal evolution of neutron stars is a very complex process with many non-linear interactions. For a decent understanding of neutron star physics, these evolutions cannot be considered isolated. A brief overview is presented, which describes the main magneto–thermal interactions that determine the fate ...

  2. XRD and neutron diffraction analyses of heat treated U-Mo/Al dispersion fuel

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ji Min; Kim, Woo Jeong; Ryu, Ho Jin; Lee, Kyu Hong; Park, Jong Man [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-10-15

    High density U Mo alloys are regarded as promising candidates for advanced research reactor fuel because they have shown stable irradiation performance when compared to other uranium alloys and compounds. However, interaction layer formation between the U Mo alloys and Al matrix degrades the irradiation performance of U Mo dispersion fuel. Therefore, addition of Ti in U Mo alloys, addition of Si in Al matrix and silicide or nitride coating on the surface of U Mo particles have been proposed in order to inhibit the interaction layer growth. In order to analyze the mechanisms of interaction layer growth inhibition by adding Ti in U Mo alloys or Si in Al matrix, accurate phase characterization of the interaction layers is required. While previous studies using X ray diffraction have been reported, laboratory X ray diffraction method has limitations such as low resolution and small measurement volume. Neutron diffraction method can be a more accurate analysis when compared with X ray diffraction method due to the large penetration depth of neutron. In this study, X ray diffraction and neutron diffraction experiments have been performed by using the laboratory X ray diffractometer and high resolution powder diffractometer (HRPD) of the HANARO research reactor in KAERI.

  3. Design of hyper-thermal neutron irradiation fields for neutron capture therapy in KUR-heavy water neutron irradiation facility. Mounting of hyper-thermal neutron converter in therapeutic collimator

    International Nuclear Information System (INIS)

    Sakurai, Y.; Kobayashi, T.

    2001-01-01

    Neutron capture therapy (NCP) using thermal neutron needs to improve of depth dose distribution in a living body. Epi-thermal neutron following moderation of fast neutron is usually used for improving of the depth dose distribution. The moderation method of fast neutron, however, gets mixed some of high energy neutron which give some of serious effects to a living body, and involves the difficulty for collimation of thermal neutron to the diseased part. Hyper-thermal neutrons, which are in an energy range of 0.1-3 eV at high temperature side of thermal neutron, are under consideration for application to the NCP. The hyper-thermal neutrons can be produced by up-scattering of thermal neutron in a high temperature material. Fast neutron components in collimator for the NCP reduce on application of the up-scattering method. Graphite at high temperature (>1000k) is used as a hyper-thermal neutron converter. The hyper-thermal neutron converter is planted to mount on therapeutic collimator which is located at the nearest side of patient for the NCP. Total neutron flux, ratio of hyper-thermal neutron to total neutron, and ratio of gamma-ray dose to neutron flux are calculated as a function of thickness of the graphite converter using monte carlo code MCNP-V4B. (M. Suetake)

  4. Neutron Diffraction Studies of Nuclear Magnetic Ordering in Copper

    DEFF Research Database (Denmark)

    Jyrkkiö, T.A.; Huiku, M.T.; Siemensmeyer, K.

    1989-01-01

    for measurements in the ordered state; both our calculations and the experiments yield 1 nW beam heating. Polarized neutron experiments show that the scattered intensities from the strong fcc reflections are severely reduced by extinction. This makes the sample not very suitable for further studies with polarized...... to depend strongly on the external magnetic field between zero and the critical fieldB c=0.25 mT, indicating the existence of at least two antiferromagnetic phases. The results are compared to previous measurements of the magnetic susceptibility. Theoretical calculations do not provide a full explanation...

  5. Condensed matter and materials research using neutron diffraction and spectroscopy: reactor and pulsed neutron sources

    International Nuclear Information System (INIS)

    Bisanti, Paola; Lovesey, S.W.

    1987-05-01

    The paper provides a short, and partial view of the neutron scattering technique applied to condensed matter and materials research. Reactor and accelerator-based neutron spectrometers are discussed, together with examples of research projects that illustrate the puissance and modern applications of neutron scattering. Some examples are chosen to show the range of facilities available at the medium flux reactor operated by Casaccia ENEA, Roma and the advanced, pulsed spallation neutron source at the Rutherford Appleton Laboratory, Oxfordshire. (author)

  6. Neutron diffraction study of history dependence in MnFeP0.6Si0.4

    International Nuclear Information System (INIS)

    Zhang, L.; Moze, O.; Prokes, K.; Tegus, O.; Brueck, E.

    2005-01-01

    In the MnFe(P,As) compounds which are promising magnetorefrigerant materials, we have studied the effect of Si substitution and successfully replaced As by Si. Surprisingly besides all the other changes, a peculiar history dependence of the magnetic phase transition was disclosed. The as-prepared sample shows a significantly lower transition temperature (namely a virgin T C ) than the sample that has experienced thermal cycling. The neutron diffraction patterns recorded during the first cooling manifest the first-order and magnetic-field-induced characters of the virgin phase transition. However, the refinement of the diffraction patterns does not provide evidence for atomic-position swapping, which might account for this history dependence

  7. Characterization of the Ljubljana TRIGA thermal column neutron radiographic facility

    International Nuclear Information System (INIS)

    Nemec, T.; Rant, J.; Kristof, E.; Glumac, B.

    1995-01-01

    An extensive characterization of the neutron beam of the existing neutron radiographic facility in the thermal column of the Ljubljana Triga Mark II research reactor is in progress. Neutron beam characteristics are needed to determine the effect of various neutron and gamma radiation on the neutron radiographic image. Commercially available medical scintillator converter screens based on Gd dioxy sulphite as well as Gd metal neutron converters are used to record neutron radiographic image. Thermal, epithermal and fast neutron fluxes were measured using Au and In activation detectors and cadmium ratio is determined. Neutron beam flux profiles are measured by film densitometry and by Au activation detector wires. By exposing films shielded by boral or lead plates individual contributions of thermal, epithermal neutrons and gamma radiation are estimated by densitometric measurements. By recording images of neutron image quality indicators BPI (Beam Purity Indicator) and SI (Sensitivity Indicator) produced by Riso, standard neutron radiography image characteristic are established. In gamma dosimetric measurements thermoluminescent detectors (CaF 2 Mn) are used. (author)

  8. Crystallite Size and Microstrain Measurement of Cathode Material after Mechanical Milling using Neutron Diffraction Technique

    Directory of Open Access Journals (Sweden)

    A. Fajar

    2010-12-01

    Full Text Available The measurements of neutron diffraction patterns of commercially product and 10 hour mechanically milled cathode material lithium cobaltites (LiCoO2 have been performed. Rietveld analysis using FullProf does not show the change of crystal structure due to milling process, but the diffraction pattern has a lower intensity and the diffraction-line was broadening. The results of line-broadening study on milled sample using Rietveld methods detected that the microstrain was occurred in the sample with value 0.127080(35 % and the average crystallite size was 424.78(20 Å.

  9. 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)

  10. Thermal neutron flux distribution in ET-RR-2 reactor thermal column

    Directory of Open Access Journals (Sweden)

    Imam Mahmoud M.

    2002-01-01

    Full Text Available The thermal column in the ET-RR-2 reactor is intended to promote a thermal neutron field of high intensity and purity to be used for following tasks: (a to provide a thermal neutron flux in the neutron transmutation silicon doping, (b to provide a thermal flux in the neutron activation analysis position, and (c to provide a thermal neutron flux of high intensity to the head of one of the beam tubes leading to the room specified for boron thermal neutron capture therapy. It was, therefore, necessary to determine the thermal neutron flux at above mentioned positions. In the present work, the neutron flux in the ET-RR-2 reactor system was calculated by applying the three dimensional diffusion depletion code TRITON. According to these calculations, the reactor system is composed of the core, surrounding external irradiation grid, beryllium block, thermal column and the water reflector in the reactor tank next to the tank wall. As a result of these calculations, the thermal neutron fluxes within the thermal column and at irradiation positions within the thermal column were obtained. Apart from this, the burn up results for the start up core calculated according to the TRITION code were compared with those given by the reactor designer.

  11. Disorder and transport properties of In3SbTe2 - an X-ray, neutron and electron diffraction study

    International Nuclear Information System (INIS)

    Schroeder, Thorsten; Rosenthal, Tobias; Grott, Sebastian; Stiewe, Christian; Boor, Johannes de; Oeckler, Oliver

    2013-01-01

    Quenched metastable In 3 SbTe 2 was investigated by X-ray and neutron powder diffraction as well as by single-crystal X-ray diffraction. The average structure corresponds to the rocksalt type, the anion position being occupied by antimony and tellurium. Neutron data indicate no antisite disorder of indium and antimony. The compound is a high-temperature phase that can be quenched to yield a metastable compound at ambient temperature which, upon heating, decomposes at ca. 320 C into InSb and InTe. Diffuse scattering in reconstructed X-ray and selected area electron diffraction patterns indicates local distortions of the crystal structure due to static atom displacement along <100> from the average positions, caused by the different size of the anions, but no superstructure. The electrical conductivity of In 3 SbTe 2 is 3.2 x 10 4 S.cm -1 at 25 C, the temperature characteristics correspond to metallic behavior. Consequently, the thermal conductivity is also rather high. The decomposition into InSb and InTe reduces the electrical conductivity by a factor of 3 in heterogeneous microstructures. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Determination of Coherency and Rigidity Temperatures in Al-Cu Alloys Using In Situ Neutron Diffraction During Casting

    Science.gov (United States)

    Drezet, Jean-Marie; Mireux, Bastien; Szaraz, Zoltan; Pirling, Thilo

    2014-08-01

    The rigidity temperature of a solidifying alloy is the temperature at which the solid phase is sufficiently coalesced to transmit tensile stress. It is a major input parameter in numerical modeling of solidification processes as it defines the point at which thermally induced deformations start to generate internal stresses in a casting. This temperature has been determined for an Al-13 wt.% Cu alloy using in situ neutron diffraction during casting in a dog-bone-shaped mold. This setup allows the sample to build up internal stress naturally as its contraction is not possible. The cooling on both sides of the mold induces a hot spot at the middle of the sample that is irradiated by neutrons. Diffraction patterns are recorded every 11 s using a large detector, and the very first change of diffraction angles allows for the determination of the rigidity temperature. We measured rigidity temperatures equal to 557°C and 548°C depending on the cooling rate for grain refined Al-13 wt.% Cu alloys. At a high cooling rate, rigidity is reached during the formation of the eutectic phase. In this case, the solid phase is not sufficiently coalesced to sustain tensile load and thus cannot avoid hot tear formation.

  13. Single-crystal neutron diffraction studies of hydrogen-bonded systems: Two recent examples from IPNS

    Energy Technology Data Exchange (ETDEWEB)

    Koetzle, Thomas F. [IPNS Division, Argonne National Laboratory, Argonne, IL 60439 (United States)], E-mail: tkoetzle@anl.gov; Piccoli, Paula M.B.; Schultz, Arthur J. [IPNS Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2009-02-21

    Beginning with work in the 1950s at the first generation of research reactors, studies of hydrogen-bonded systems have been a prime application for single-crystal neutron diffraction. The range of systems studied was extended in the 1960s and 1970s, with the advent of high flux reactor sources, and beginning around 1980 studies at pulsed neutron sources have made increasingly important contributions. Recently at the Argonne Intense Pulsed Neutron Source (IPNS), working with collaborators, we completed two studies of hydrogen-bonded systems that will serve to illustrate topics of current interest. In the first study, on andrographolide, an active diterpenoid natural product, our neutron diffraction results definitively characterize the hydrogen-bonding interactions. The second IPNS study is on tetraacetylethane (TAE), a {beta}-diketone enol system with a very short, strong intramolecular O-H...O hydrogen bond. At IPNS, we have determined the neutron crystal structure of TAE at five temperatures between 20 and 298 K to investigate changes in the structure with temperature and to probe for disorder. Despite the successes illustrated by the two examples presented here and by many other studies, at present applications of single-crystal neutron diffraction continue to be extremely flux limited and constrained by the requirement for mm-size crystals for many problems. These limitations are being addressed through the realization of powerful instruments at a new generation of pulsed neutron sources, including in the USA the TOPAZ and MaNDi single-crystal diffractometers that are under development at the Spallation Neutron Source (SNS)

  14. Single-crystal neutron diffraction studies of hydrogen-bonded systems: Two recent examples from IPNS

    Science.gov (United States)

    Koetzle, Thomas F.; Piccoli, Paula M. B.; Schultz, Arthur J.

    2009-02-01

    Beginning with work in the 1950s at the first generation of research reactors, studies of hydrogen-bonded systems have been a prime application for single-crystal neutron diffraction. The range of systems studied was extended in the 1960s and 1970s, with the advent of high flux reactor sources, and beginning around 1980 studies at pulsed neutron sources have made increasingly important contributions. Recently at the Argonne Intense Pulsed Neutron Source (IPNS), working with collaborators, we completed two studies of hydrogen-bonded systems that will serve to illustrate topics of current interest. In the first study, on andrographolide, an active diterpenoid natural product, our neutron diffraction results definitively characterize the hydrogen-bonding interactions. The second IPNS study is on tetraacetylethane (TAE), a β-diketone enol system with a very short, strong intramolecular O-H⋯O hydrogen bond. At IPNS, we have determined the neutron crystal structure of TAE at five temperatures between 20 and 298 K to investigate changes in the structure with temperature and to probe for disorder. Despite the successes illustrated by the two examples presented here and by many other studies, at present applications of single-crystal neutron diffraction continue to be extremely flux limited and constrained by the requirement for mm-size crystals for many problems. These limitations are being addressed through the realization of powerful instruments at a new generation of pulsed neutron sources, including in the USA the TOPAZ and MaNDi single-crystal diffractometers that are under development at the Spallation Neutron Source (SNS).

  15. Single-crystal neutron diffraction studies of hydrogen-bonded systems: Two recent examples from IPNS

    International Nuclear Information System (INIS)

    Koetzle, Thomas F.; Piccoli, Paula M.B.; Schultz, Arthur J.

    2009-01-01

    Beginning with work in the 1950s at the first generation of research reactors, studies of hydrogen-bonded systems have been a prime application for single-crystal neutron diffraction. The range of systems studied was extended in the 1960s and 1970s, with the advent of high flux reactor sources, and beginning around 1980 studies at pulsed neutron sources have made increasingly important contributions. Recently at the Argonne Intense Pulsed Neutron Source (IPNS), working with collaborators, we completed two studies of hydrogen-bonded systems that will serve to illustrate topics of current interest. In the first study, on andrographolide, an active diterpenoid natural product, our neutron diffraction results definitively characterize the hydrogen-bonding interactions. The second IPNS study is on tetraacetylethane (TAE), a β-diketone enol system with a very short, strong intramolecular O-H...O hydrogen bond. At IPNS, we have determined the neutron crystal structure of TAE at five temperatures between 20 and 298 K to investigate changes in the structure with temperature and to probe for disorder. Despite the successes illustrated by the two examples presented here and by many other studies, at present applications of single-crystal neutron diffraction continue to be extremely flux limited and constrained by the requirement for mm-size crystals for many problems. These limitations are being addressed through the realization of powerful instruments at a new generation of pulsed neutron sources, including in the USA the TOPAZ and MaNDi single-crystal diffractometers that are under development at the Spallation Neutron Source (SNS).

  16. Residual stress measurements in thick structural weldments by means of neutron diffraction

    International Nuclear Information System (INIS)

    Ohms, C.; Youtsos, A.G.; Idsert, P. v.d.; Timke, T.

    2000-01-01

    Welding residual stresses in large structural components are a major concern with respect to their performance and lifetime. In large structures reasonable thermal stress relief treatment is usually impossible due to the component size. On the other hand, prediction of welding stresses by numerical modelling has not yet proven to be generally reliable, while the experimental determination of such stresses remains a demanding task. At the high flux reactor (HFR), Petten, a new residual stress diffractometer has been installed recently capable of handling of components up to 1000 kg - the large component neutron diffraction facility (LCNDF). It has facilitated residual stress measurements in two large welded components, of which results are presented here. The first component represents a bi-metallic weld in form of a pipe of 25 mm wall thickness. Three dimensional measurements of residual stress are discussed in detail. The second specimen is a 66 mm wall thickness austenitic steel nuclear piping weld. Results on relief of strain within the weld through post weld heat treatment (PWHT) are presented. Additionally results obtained earlier at former CRNL (CAN) on a section of a thick nuclear piping weld are presented in order to illustrate the variation in the reference lattice parameter trough the weld and the heat affected zone (HAZ). These results clearly show the necessity to determine the reference parameters for each location in all measurement directions by means of measurements in small coupons free of macro-stresses. (orig.)

  17. Residual stress analysis for engineering applications by means of neutron diffraction

    International Nuclear Information System (INIS)

    Gnaeupel-Herold, T.; Brand, P.C.; Prask, H.J.

    1999-01-01

    Residual stresses originate from spatial differences in plastic deformation, temperature, or phase distribution, introduced by manufacturing processes or during service. Engineering parts and materials experience mechanical, thermal, and chemical loads during their service, and most of these loads introduce stresses that are superimposed on the already existing residual stresses. Residual stresses can therefore limit or improve life and strength of engineering parts; knowledge and understanding of these stresses is therefore critical for optimizing strength and durability. The economic and scientific importance of neutron diffraction residual stress analysis has led to an increasing number of suitable instruments worldwide. All of the major sources due in the next several years will have instruments for the sole purpose of performing residual stress and texture measurements. Recently, a dedicated, state-of-the-art diffractometer has been installed at the National Institute of Standards and Technology reactor. It has been used for a variety of measurements on basic and engineering stress problems. Among the most prominent examples that have been investigated in collaboration with industrial and academic partners are residual stresses in rails, weldments, and plasma-sprayed coatings

  18. In situ neutron diffraction investigation on the phase transformation sequence of kaolinite and halloysite to mullite

    Energy Technology Data Exchange (ETDEWEB)

    Tezuka, Nobuo [Department of Applied Physics, Curtin University of Technology, GPO Box U1987, Perth, WA 6845 (Australia); Low, It-Meng [Department of Applied Physics, Curtin University of Technology, GPO Box U1987, Perth, WA 6845 (Australia)]. E-mail: J.Low@curtin.edu.au; Davies, Ian J. [Department of Mechanical Engineering, Curtin University of Technology, GPO Box U1987, Perth, WA 6845 (Australia); Prior, Michael [Bragg Institute, ANSTO, PMB 1, Menai, NSW 2234 (Australia); Studer, Andrew [Bragg Institute, ANSTO, PMB 1, Menai, NSW 2234 (Australia)

    2006-11-15

    'Kaolin' is a major raw material for the fabrication of conventional ceramics. In this work the authors have investigated the thermal phase transformation of mullite from two different types of kaolin (kaolinite and halloysite), with or without alumina matrix constraint, during heating up to 1500 deg. C and then cooling using in situ neutron diffraction. Mullitization was initiated upon heating to 1200 deg. C for all specimens and followed spinel formation at 1100 deg. C. Above this temperature, however, evolution of the main phases, i.e., mullite, cristobalite and corundum, was influenced by the presence of impurities, initial type of silica, and alumina constraint. The relative amount of mullite was largest for the pure kaolinite specimen, particularly during heating, and this was attributed to the presence of a glassy phase. However, kaolinite with alumina suppressed the crystallization of cristobalite from the glassy phase upon cooling due to a reaction between alumina and amorphous silica, consequently resulting in an amount of mullite as for the pure kaolinite specimen (approximately 65 wt%). Halloysite was less active in terms of mullitization due to the lower level of initial impurities and greater amount of cristobalite, particularly for the alumina-constrained specimen. However, the final amount of mullite derived from the pure halloysite specimen was similar to that as from the kaolinite specimen.

  19. In situ neutron diffraction investigation on the phase transformation sequence of kaolinite and halloysite to mullite

    International Nuclear Information System (INIS)

    Tezuka, Nobuo; Low, It-Meng; Davies, Ian J.; Prior, Michael; Studer, Andrew

    2006-01-01

    'Kaolin' is a major raw material for the fabrication of conventional ceramics. In this work the authors have investigated the thermal phase transformation of mullite from two different types of kaolin (kaolinite and halloysite), with or without alumina matrix constraint, during heating up to 1500 deg. C and then cooling using in situ neutron diffraction. Mullitization was initiated upon heating to 1200 deg. C for all specimens and followed spinel formation at 1100 deg. C. Above this temperature, however, evolution of the main phases, i.e., mullite, cristobalite and corundum, was influenced by the presence of impurities, initial type of silica, and alumina constraint. The relative amount of mullite was largest for the pure kaolinite specimen, particularly during heating, and this was attributed to the presence of a glassy phase. However, kaolinite with alumina suppressed the crystallization of cristobalite from the glassy phase upon cooling due to a reaction between alumina and amorphous silica, consequently resulting in an amount of mullite as for the pure kaolinite specimen (approximately 65 wt%). Halloysite was less active in terms of mullitization due to the lower level of initial impurities and greater amount of cristobalite, particularly for the alumina-constrained specimen. However, the final amount of mullite derived from the pure halloysite specimen was similar to that as from the kaolinite specimen

  20. In situ observation of the reaction of scandium and carbon by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Juarez-Arellano, Erick A., E-mail: eajuarez@unpa.edu.m [Institut fuer Geowissenschaften, Universitaet Frankfurt, Altenhoeferallee 1, 60438 Frankfurt a.M. (Germany); Universidad del Papaloapan, Circuito Central 200, Parque Industrial, Tuxtepec 68301 (Mexico); Winkler, Bjorn [Institut fuer Geowissenschaften, Universitaet Frankfurt, Altenhoeferallee 1, 60438 Frankfurt a.M. (Germany); Vogel, Sven C. [Los Alamos National Laboratory, Lujan Center. Mail Stop H805, Los Alamos, NM 87545 (United States); Senyshyn, Anatoliy [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universitaet Muenchen, Lichtenbergstr. 1, D-85747 Garching (Germany); Materialwissenschaft, TU Darmstadt, Petersensstr. 23, D-64287 Darmstadt (Germany); Kammler, Daniel R. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Avalos-Borja, Miguel [CNyN, UNAM, A. Postal 2681, Ensenada, B.C. (Mexico)

    2011-01-05

    Research highlights: {yields} Exist two ScC cubic phases with B1-structure type differing in site occupancy of C. {yields} A new orthorhombic scandium carbide phase is formed at 1473(50) K. {yields} The recrystallization of alpha-Sc occurs between 1000 and 1223 K. - Abstract: The formation of scandium carbides by reaction of the elements has been investigated by in situ neutron diffraction up to 1823 K. On heating, the recrystallization of {alpha}-Sc occurs between 1000 and 1223 K. The formation of Sc{sub 2}C and ScC (NaCl-B1 type structure) phases has been detected at 1323 and 1373 K, respectively. The formation of a new orthorhombic scandium carbide phase was observed at 1473(50) K. Once the scandium carbides are formed they are stable upon heating or cooling. No other phases were detected in the present study, in which the system was always carbon saturated. The thermal expansion coefficients of all phases have been determined, they are constant throughout the temperature interval studied.

  1. Textures of iron oxide ores by neutron diffraction and topotactical relation

    International Nuclear Information System (INIS)

    Wagner, F.; Esling, C.; Baro, R.; Englander, M.

    1977-01-01

    Two samples are cut from a polycrystalline haematite block. The first one is directly submitted to texture analysis by neutron diffraction, whereas the second one is first reduced into magnetite. The comparison of both textures is in agreement with a topotactical relationship previously reported for monocrystals. (orig.) [de

  2. Neutron diffraction measurements of residual stress in a powder metallurgy component

    International Nuclear Information System (INIS)

    Schneider, L.C.R.; Hainsworth, S.V.; Cocks, A.C.F.; Fitzpatrick, M.E.

    2005-01-01

    Residual stresses in a typical industrial green component were determined using neutron diffraction. The measured residual stresses were found to correlate with cross-sectional variations. Residual stress at the edge of the compact in contact with the die wall during compaction reached up to +80 MPa (tension) and -100 MPa (compression)

  3. Neutron diffraction from the vortex lattice in the heavy-fermion superconductor UPt3

    DEFF Research Database (Denmark)

    Kleiman, R.N.; Broholm, C.; Aeppli, G.

    1992-01-01

    We have used neutron diffraction to observe the vortex lattice of UPt3. This is the first such measurement in a heavy-fermion system, a superconductor below 1 K, or in a system with such a long magnetic penetration depth (6000 +/- 75 angstrom). It also provides the first value for the pair...

  4. Combined X-ray and neutron fibre diffraction studies of biological and synthetic polymers

    International Nuclear Information System (INIS)

    Parrot, I.M.; Urban, V.; Gardner, K.H.; Forsyth, V.T.

    2005-01-01

    The fibrous state is a natural one for polymer molecules which tend to assume regular helical conformations rather than the globular structures characteristic of many proteins. Fibre diffraction therefore has broad application to the study of a wide range of biological and synthetic polymers. The purpose of this paper is to illustrate the general scope of the method and in particular to demonstrate the impact of a combined approach involving both X-ray and neutron diffraction methods. While the flux of modern X-ray synchrotron radiation sources allows high quality datasets to be recorded with good resolution within a very short space of time, neutron studies can provide unique information through the ability to locate hydrogen or deuterium atoms that are often difficult or impossible to locate using X-ray methods. Furthermore, neutron fibre diffraction methods can, through the ability to selectively label specific parts of a structure, be used to highlight novel aspects of polymer structure that can not be studied using X-rays. Two examples are given. The first describes X-ray and neutron diffraction studies of conformational transitions in DNA. The second describes structural studies of the synthetic high-performance polymer poly(p-phenylene terephthalamide) (PPTA), known commercially as Kevlar[reg] or Twaron[reg

  5. Combined X-ray and neutron fibre diffraction studies of biological and synthetic polymers.

    Energy Technology Data Exchange (ETDEWEB)

    Parrot, I. M. [Institut Laue-Langevin (ILL); Urban, Volker S [ORNL; Gardner, K. H. [DuPont Experimental Station; Forsyth, V. T. [Institut Laue Langevin and Keele University

    2005-04-01

    The fibrous state is a natural one for polymer molecules which tend to assume regular helical conformations rather than the globular structures characteristic of many proteins. Fibre diffraction therefore has broad application to the study of a wide range of biological and synthetic polymers. The purpose of this paper is to illustrate the general scope of the method and in particular to demonstrate the impact of a combined approach involving both X-ray and neutron diffraction methods. While the flux of modern X-ray synchrotron radiation sources allows high quality datasets to be recorded with good resolution within a very short space of time, neutron studies can provide unique information through the ability to locate hydrogen or deuterium atoms that are often difficult or impossible to locate using X-ray methods. Furthermore, neutron fibre diffraction methods can, through the ability to selectively label specific parts of a structure, be used to highlight novel aspects of polymer structure that can not be studied using X-rays. Two examples are given. The first describes X-ray and neutron diffraction studies of conformational transitions in DNA. The second describes structural studies of the synthetic high-performance polymer poly(p-phenylene terephthalamide) (PPTA), known commercially as Kevlar{reg_sign} or Twaron{reg_sign}.

  6. Combined X-ray and neutron fibre diffraction studies of biological and synthetic polymers

    Science.gov (United States)

    Parrot, I. M.; Urban, V.; Gardner, K. H.; Forsyth, V. T.

    2005-08-01

    The fibrous state is a natural one for polymer molecules which tend to assume regular helical conformations rather than the globular structures characteristic of many proteins. Fibre diffraction therefore has broad application to the study of a wide range of biological and synthetic polymers. The purpose of this paper is to illustrate the general scope of the method and in particular to demonstrate the impact of a combined approach involving both X-ray and neutron diffraction methods. While the flux of modern X-ray synchrotron radiation sources allows high quality datasets to be recorded with good resolution within a very short space of time, neutron studies can provide unique information through the ability to locate hydrogen or deuterium atoms that are often difficult or impossible to locate using X-ray methods. Furthermore, neutron fibre diffraction methods can, through the ability to selectively label specific parts of a structure, be used to highlight novel aspects of polymer structure that can not be studied using X-rays. Two examples are given. The first describes X-ray and neutron diffraction studies of conformational transitions in DNA. The second describes structural studies of the synthetic high-performance polymer poly(p-phenylene terephthalamide) (PPTA), known commercially as Kevlar® or Twaron®.

  7. Combined X-ray and neutron fibre diffraction studies of biological and synthetic polymers

    Energy Technology Data Exchange (ETDEWEB)

    Parrot, I.M. [Institut Laue Langevin, 6 Rue Jules Horowitz, 38042 Grenoble Cedex 9 (France); Institute of Science and Technology in Medicine, Keele University Medical School, Staffordshire ST4 7QB (United Kingdom); Urban, V. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6100 (United States); Gardner, K.H. [Department of Materials Science and Engineering University of Delaware, Newark, DE 19719 (United States); Forsyth, V.T. [Institut Laue Langevin, 6 Rue Jules Horowitz, 38042 Grenoble Cedex 9 (France) and Institute of Science and Technology in Medicine, Keele University Medical School, Staffordshire ST4 7QB (United Kingdom)]. E-mail: tforsyth@ill.fr

    2005-08-15

    The fibrous state is a natural one for polymer molecules which tend to assume regular helical conformations rather than the globular structures characteristic of many proteins. Fibre diffraction therefore has broad application to the study of a wide range of biological and synthetic polymers. The purpose of this paper is to illustrate the general scope of the method and in particular to demonstrate the impact of a combined approach involving both X-ray and neutron diffraction methods. While the flux of modern X-ray synchrotron radiation sources allows high quality datasets to be recorded with good resolution within a very short space of time, neutron studies can provide unique information through the ability to locate hydrogen or deuterium atoms that are often difficult or impossible to locate using X-ray methods. Furthermore, neutron fibre diffraction methods can, through the ability to selectively label specific parts of a structure, be used to highlight novel aspects of polymer structure that can not be studied using X-rays. Two examples are given. The first describes X-ray and neutron diffraction studies of conformational transitions in DNA. The second describes structural studies of the synthetic high-performance polymer poly(p-phenylene terephthalamide) (PPTA), known commercially as Kevlar[reg] or Twaron[reg].

  8. Neutron diffraction study on the medium and short-range order of ternary chalcogenide glasses

    Czech Academy of Sciences Publication Activity Database

    Neov, S.; Gerasimova, I.; Skordeva, E.; Arsova, D.; Pamukchieva, V.; Mikula, Pavol; Lukáš, Petr; Sonntag, R.

    1999-01-01

    Roč. 34, - (1999), s. 3669-3676 ISSN 0022-2461 R&D Projects: GA ČR GV202/97/K038 Keywords : neutron diffraction * short-range order * chalcogenide glasses Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.786, year: 1999

  9. Neutron diffraction studies of Ho1-xYxNi2B2C compounds

    DEFF Research Database (Denmark)

    Chang, L.J.; Tomy, C.V.; Paul, D.M.K.

    1996-01-01

    Neutron diffraction measurements have been carried out to investigate the nature of magnetic ordering in Ho(1-x)Y(x)Ni(2)B(2)C (x = 0, 0.1 and 0.2) compounds. HoNi(2)B(2)C shows a complex type of magnetic ordering below the superconducting transition, with a commensurate antiferromagnetic ordering...

  10. Analytical model for neutron diffraction peak shifts due to the surface effect

    Czech Academy of Sciences Publication Activity Database

    Šaroun, Jan; Kornmeier, J. R.; Hofmann, M.; Mikula, Pavol; Vrána, Miroslav

    2013-01-01

    Roč. 46, č. 6 (2013), s. 628-638 ISSN 0021-8898 R&D Projects: GA ČR GAP204/10/0654 Institutional support: RVO:61389005 Keywords : residual-stress * neutron diffraction * Monte Carlo simulation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.950, year: 2013

  11. Residual stresses in cold-coiled helical compression springs for automotive suspensions measured by neutron diffraction

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Brand, P. C.; Drews, A. R.; Krause, A.; Lowe-Ma, C.

    2004-01-01

    Roč. 367, 1-2 (2004), s. 306-311 ISSN 0921-5093 Institutional research plan: CEZ:AV0Z2043910 Keywords : residual stress, automotive springs, neutron diffraction Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 1.445, year: 2004

  12. 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...

  13. Neutron Diffraction from the Second Layer of 4He on Graphite

    DEFF Research Database (Denmark)

    da Costa Carneiro, Kim; Passell, L.; Thomlinson, W.

    1981-01-01

    Neutron diffraction has been used to study the second atomic layer of **4He adsorbed on graphite. As the **4He-coverage exceeds the first layer, the second initially forms a fluid phase. But when there is enough **4He in the third layer to compress the second, this layer solidifies. The structure...

  14. Neutron diffraction study of a nitrogen martensitic steel 0Kh16N4AB under load

    Czech Academy of Sciences Publication Activity Database

    Sumin, V. V.; Papushkin, I.V.; Bannykh, O.A.; Blinov, V.M.; Lukáš, Petr

    2008-01-01

    Roč. 105, č. 1 (2008), s. 88-91 ISSN 0031-918X Institutional research plan: CEZ:AV0Z10480505 Keywords : steel 0Kh16N4AB * neutron diffraction * FSD Subject RIV: BG - Nuclear, Atomic and Molecular Physics , Colliders Impact factor: 0.412, year: 2008

  15. Anomalous spin distribution in the superconducting ferromagnet UCoGe studied by polarized neutron diffraction

    NARCIS (Netherlands)

    Prokeš, K.; de Visser, A.; Huang, Y.K.; Fåk, B.; Ressouche, E.

    2010-01-01

    We report a polarized neutron-diffraction study conducted to reveal the nature of the weak ferromagnetic moment in the superconducting ferromagnet UCoGe. We find that the ordered moment in the normal phase in low magnetic fields (B∥c) is predominantly located at the U atom and has a magnitude of

  16. Residual stresses determination by neutron diffraction in a 100Cr6 chromium steel bearing ring

    Czech Academy of Sciences Publication Activity Database

    Rogante, M.; Martinat, G.; Mikula, Pavol; Vrána, Miroslav

    2013-01-01

    Roč. 51, č. 5 (2013), s. 275-281 ISSN 0023-432X R&D Projects: GA MŠk(XE) LM2011019 Institutional support: RVO:61389005 Keywords : 100Cr6 steel * rings * martensitic hardening * tempering * residual stress es * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.546, year: 2013

  17. Fly's Eye: a counting camera for thermal neutrons, some applications, problems, and prospects

    International Nuclear Information System (INIS)

    Davidson, J.B.

    1975-01-01

    An area detector for thermal neutrons based on image intensification techniques is described and some capabilities and limitations of the detection system are discussed. Among the former are high spatial resolution high instantaneous counting rate, electronic zoom, time-gating, and integration. The detector is limited in that the maximum counting rate for a resolution element is 60 regularly spaced counts per second. Also, the nonuniformity of response over the detector limits the useful size and requires point-by-point calibration. In addition, a higher efficiency for neutron detection would be desirable. Some typical applications of the system are: crystal inspection, neutron magnetic diffraction topography, and searches for temperature induced changes in diffraction patterns. The future application of solid state television sensors and microchannel plate intensifiers to improve the system are briefly mentioned. (U.S.)

  18. Fly's eye: a counting camera for thermal neutrons: some applications, problems, and prospects

    International Nuclear Information System (INIS)

    Davidson, J.B.

    1976-01-01

    An area detector for thermal neutrons based on image intensification techniques is described. Some capabilities and limitations of the detection system are discussed. Among the former are high spatial resolution, high instantaneous counting rate, electronic zoom, time-gating, and integration. The detector is limited in that the maximum counting rate for a resolution element is 60 regularly spaced counts per second. Also, the nonuniformity of response over the detector puts a limit on the useful size and necessitates point-by-point calibration. In addition, a higher efficiency for neutron detection would be desirable. Some typical applications of the system are crystal inspection, neutron magnetic diffraction topography, and searches for temperature-induced changes in diffraction patterns. The future application of solid-state television sensors and microchannel-plate intensifiers to improve the system is briefly mentioned

  19. In situ Neutron Diffraction during Casting: Determination of Rigidity Point in Grain Refined Al-Cu Alloys.

    Science.gov (United States)

    Drezet, Jean-Marie; Mireux, Bastien; Szaraz, Zoltan; Pirling, Thilo

    2014-02-12

    The rigidity temperature of a solidifying alloy is the temperature at which the solid plus liquid phases are sufficiently coalesced to transmit long range tensile strains and stresses. It determines the point at which thermally induced deformations start to generate internal stresses in a casting. As such, it is a key parameter in numerical modelling of solidification processes and in studying casting defects such as solidification cracking. This temperature has been determined in Al-Cu alloys using in situ neutron diffraction during casting in a dog bone shaped mould. In such a setup, the thermal contraction of the solidifying material is constrained and stresses develop at a hot spot that is irradiated by neutrons. Diffraction peaks are recorded every 11 s using a large detector, and their evolution allows for the determination of the rigidity temperatures. We measured rigidity temperatures equal to 557 °C and 548 °C, depending on cooling rate, for a grain refined Al-13 wt% Cu alloy. At high cooling rate, rigidity is reached during the formation of the eutectic phase and the solid phase is not sufficiently coalesced, i.e. , strong enough, to avoid hot tear formation.

  20. In situ Neutron Diffraction during Casting: Determination of Rigidity Point in Grain Refined Al-Cu Alloys

    Directory of Open Access Journals (Sweden)

    Jean-Marie Drezet

    2014-02-01

    Full Text Available The rigidity temperature of a solidifying alloy is the temperature at which the solid plus liquid phases are sufficiently coalesced to transmit long range tensile strains and stresses. It determines the point at which thermally induced deformations start to generate internal stresses in a casting. As such, it is a key parameter in numerical modelling of solidification processes and in studying casting defects such as solidification cracking. This temperature has been determined in Al-Cu alloys using in situ neutron diffraction during casting in a dog bone shaped mould. In such a setup, the thermal contraction of the solidifying material is constrained and stresses develop at a hot spot that is irradiated by neutrons. Diffraction peaks are recorded every 11 s using a large detector, and their evolution allows for the determination of the rigidity temperatures. We measured rigidity temperatures equal to 557 °C and 548 °C, depending on cooling rate, for a grain refined Al-13 wt% Cu alloy. At high cooling rate, rigidity is reached during the formation of the eutectic phase and the solid phase is not sufficiently coalesced, i.e., strong enough, to avoid hot tear formation.

  1. The application of X-ray, γ-ray and neutron diffraction to the characterization of single crystal perfection

    International Nuclear Information System (INIS)

    Freund, A.; Schneider, J.R.

    1976-01-01

    The work is divided into the following three chapters: 1) diffraction by perfect and imperfect crystals, 2) experimental apparatus (describing gamma ray, X-ray and neutron diffractometers), 3) application of diffraction methods to the development of neutron monochromators. (WBU) [de

  2. Crystal structure solution of hydrides containing natEu from neutron powder diffraction data

    International Nuclear Information System (INIS)

    Kohlmann, H.

    1999-01-01

    Complete text of publication follows. The location of hydrogen in crystal structures of metal hydrides usually requires neutron diffraction data. Some elements, however, show excessively high absorption cross sections, σ a , for neutrons, thus making this technique seemingly impractical. Therefore no complete, refined crystal structure data of europium hydrides (σ a ( nat Eu) = .4530 barns at λ = 179.8 pm [1]) have been reported so far. It is shown that the absorption can be reduced to a value reasonable for neutron diffraction experiments by taking advantage of the wavelength dependence of σ a combined with the use of annular samples at advanced diffractometers. Neutron powder diffraction data on several nat Eu containing deuterides suitable for the ab initio crystal structure solution and refinement have been taken at D20 and D4 (ILL, Grenoble). The crystal chemistry of these europium hydrides, among them the two new compounds EuMg 2 H 6 and EuMgH 4 [2], is discussed. (author) [1] V.F. Sears, Neutron News 1992, 3, 26-37.; [2] H. Kohlmann, F. Gingl, T. Hansen, K. Yvon, Angew. Chem. Int. Ed. Eng. 1999, 38, accepted

  3. CaSO{sub 4}:Dy microphosphor for thermal neutron dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Bhadane, Mahesh S. [Microtron Accelerator Laboratory, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Mandlik, Nandkumar [Department of Physics, Fergusson College, Savitribai Phule Pune University, Pune 411007 (India); Patil, B.J. [Department of Physics, Abasaheb Garware College, Pune 411004 (India); Dahiwale, S.S.; Sature, K.R.; Bhoraskar, V.N. [Microtron Accelerator Laboratory, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Dhole, S.D., E-mail: sanjay@physics.unipune.ac.in [Microtron Accelerator Laboratory, Department of Physics, Savitribai Phule Pune University, Pune 411007 (India)

    2016-02-15

    Dysprosium-doped calcium sulphate (CaSO{sub 4}:Dy) microphosphor was synthesized by acid re-crystallization method and its thermoluminescence (TL) properties irradiated with thermal neutrons was studied. Structural and morphological characteristics have been studied using X-ray diffraction and SEM which mainly exhibits a orthorhombic structure with particle size of 200 to 250 µm. Moreover, thermal neutron dosimetric characteristics of the microphosphor such as thermoluminescence glow curve, TL dose–response have been studied. This microphosphor powder represents a TL glow peak (T{sub max}) centered at around 240 °C. The TL response of CaSO{sub 4}:Dy microphosphor as a function of thermal neutron fluence is observed to be very linear upto the fluence of 52×10{sup 11} n/cm{sup 2} and further saturates. In addition, TL glow curves were deconvoluted by computerized glow curve deconvolution (CGCD) method and corresponding trapping parameters have been determined. It has been found that for every deconvoluted peak there is change in the order of kinetics. Overall, the experimental results show that the CaSO{sub 4}:Dy microphosphor can have potential to be an effective thermal neutron dosimetry. - Highlights: • Acid-recrystallization method is used to prepare CaSO{sub 4}:Dy microphosphor • CaSO{sub 4}:Dy phosphor irradiated thermal neutrons for dosimetric application. • TL response curve showed to be a perfect linear. • Trapping parameters has been calculated using CGCD curve fitting.

  4. Evidence for existence of functional monoclinic phase in sodium niobate based solid solution by powder neutron diffraction

    Science.gov (United States)

    Mishra, S. K.; Jauhari, Mrinal; Mittal, R.; Krishna, P. S. R.; Reddy, V. R.; Chaplot, S. L.

    2018-04-01

    We have carried out systematic temperature-dependent neutron diffraction measurements in conjunction with dielectric spectroscopy from 6 to 300 K for sodium niobate based compounds (1-x) NaNbO3-xBaTiO3 (NNBTx). The dielectric constant is measured as a function of both temperature and frequency. It shows an anomaly at different temperatures in cooling and heating cycles and exhibits a large thermal hysteresis of ˜150 K for the composition x = 0.03. The dielectric constant is found to be dispersive in nature and suggests a relaxor ferroelectric behavior. In order to explore structural changes as a function of temperature, we analyzed the powder neutron diffraction data for the compositions x = 0.03 and 0.05. Drastic changes are observed in the powder profiles near 2θ ˜ 30.6°, 32.1°, and 34.6° in the diffraction pattern below 200 K during cooling and above 190 K in heating cycles, respectively. The disappearance of superlattice reflection and splitting in main perovskite peaks provide a signature for structural phase transition. We observed stabilization of a monoclinic phase (Cc) at low temperature. This monoclinic phase is believed to provide a flexible polarization rotation and considered to be directly linked to the high performance piezoelectricity in materials. The thermal hysteresis for composition x = 0.03 is larger than that for x = 0.05. This suggests that the addition of BaTiO3 to NaNbO3 suppresses the thermal hysteresis. It is also observed that the structural phase transition temperature decreases upon increasing the dopant concentration.

  5. Using thermalizers in measuring 'Ukryttia' object's FCM neutron fluxes

    CERN Document Server

    Krasnyanskaya, O G; Odinokin, G I; Pavlovich, V N

    2003-01-01

    The results of research of a thermalizer (heater) width influence on neutron thermalization efficiency during FCM neutron flux measuring in the 'Ukryttia' are described. The calculations of neutron flux densities were performed by the Monte-Carlo method with the help of computer code MCNP-4C for FCM different models.Three possible installations of detectors were considered: on FCM surface,inside the FCM, and inside the concrete under the FCM layer. It was shown,that in order to increase the sensitivity of neutron detectors in intermediate and fast neutrons field,and consequently, to decrease the dependence of the readings of spectral distribution of neutron flux,it is necessary to position the detector inside the so-called thermalizer or heater. The most reasonable application of thick 'heaters' is the situation, when the detector is placed on FCM surface.

  6. Thermal neutron standard fields with the KUR heavy water facility

    International Nuclear Information System (INIS)

    Kanda, K.; Kobayashi, K.; Shibata, T.

    1978-01-01

    A heavy water facility attached to the KUR (Kyoto University Reactor, swimming pool type, 5 MW) yields pure thermal neutrons in the Maxwellian distribution. The facility is faced to the core of KUR and it contains about 2 tons of heavy water. The thickness of the layer is about 140 cm. The neutron spectrum was measured with the time of flight technique using a fast chopper. The measured spectrum was in good agreement with the Maxwellian distribution in all energy region for thermal neutrons. The neutron temperature was slightly higher than the heavy water temperature. The contamination of epithermal and fast neutrons caused by photo-neutrons of the γ-n reaction of heavy water was very small. The maximum intensity of thermal neutrons is 3x10 11 n/cm 2 sec. When the bismuth scatterer is attached, the gamma rays contamination is eliminated by the ratio of 0.05 of gamma rays to neutrons in rem. This standard neutron field has been used for such experiments as thermal neutron cross section measurement, detector calibration, activation analysis, biomedical purposes etc. (author)

  7. High-resolution neutron powder-diffraction in CMR manganates

    Energy Technology Data Exchange (ETDEWEB)

    Suard, E; Radaelli, P G [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    Manganese-oxide materials have recently been the subject of renewed attention, due to the `colossal` magnetoresistance (CMR) displayed near the spin-ordering temperature T{sub c} by some of these compounds. CMR has been evidenced in at least three families of manganese oxides. In most cases, the CMR compounds behave as paramagnetic semiconductors at high temperatures, and as ferromagnetic metals below T{sub c}. The study of this metallization process has lead some theorists to challenge its traditional interpretation in terms of the so-called double-exchange mechanism, and to propose alternative scenarios in which the coupling of the charge carriers with the lattice plays a paramount role. Powder diffraction method, being at the forefront of CMR research is presented. (author). 4 refs.

  8. Measurement of residual stress in textured Al alloy by neutron diffraction method

    International Nuclear Information System (INIS)

    Okido, S.; Hayashi, M.; Tanaka, K.; Akiniwa, Y.; Minakawa, N.; Morii, Y.

    1999-01-01

    Residual stress generated in a shrunken aluminum alloy specimen, which was prepared for the round robin test conducted by VAMAS (Versailles Project on Advanced Materials and Standards) TWA-20 organized for the purpose of standardizing residual stress measurement methods, was evaluated by a neutron diffraction method. The main purpose of the round robin test was to assess the reproducibility of data obtained with the measurement facilities of the participants. The general standard of the Residual Stress Analyzer (RESA) constructed in the Japan Atomic Energy Research Institute was verified from the measured residual strains, which were equivalent to the values calculated by FEM and values measured by the research facilities in North America. Residual stress was calculated from residual strain in three perpendicular directions. The diffraction intensities were dependent on measurement directions since the prepared specimen possessed texture. Diffraction profiles in directions having a weak diffraction intensity caused an inaccurate evaluation of the residual stress. To solve this problem, a new method for evaluating residual stress with respect to diffraction plane dependency of the elastic constant was applied. The diffraction plane giving the highest intensity among 110, 200, and 220 diffraction was used to evaluate the residual strain in each of three directions. The residual strain obtained on the used diffraction plane was converted to the equivalent strain for the defined diffraction plane using the ratio of elastic constants of these two planes. The developed evaluation method achieved highly accurate measurement and remarkable efficiency in the measurement process. (author)

  9. New developments of TOF neutron diffraction at the IBR-2 pulsed reactor

    International Nuclear Information System (INIS)

    Balagurov, Anatoli M.

    2001-01-01

    Development of high-resolution RTOF Fourier technique for powder neutron diffraction studies is being continued at the IBR-2 pulsed reactor in Dubna. Besides some technical improvements in the operating HRFD instrument, a new dedicated instrument, Fourier Strain Diffractometer (FSD), for investigation of residual stresses in bulk materials has been constructed at IBR-2 in 1999. With a new HRFD Fourier chopper smaller than 10 μs TOF contribution in a resolution function was obtained in the experiment with perfect Si single crystal. A series of diffraction experiments with the beams from a new methane cold neutron moderator installed at the IBR-2 in 1999 is discussed. A comparison with the results obtained with the conventional water comb-like moderator shows that for various types of experiments, which are performed at HRFD and DN-2 diffractometers, the methane cold neutron source provides better conditions. (author)

  10. Rietveld refinement with time-of-flight powder diffraction data from pulsed neutron sources

    International Nuclear Information System (INIS)

    David, W.I.F.; Jorgensen, J.D.

    1990-10-01

    The recent development of accelerator-based pulsed neutron sources has led to the widespread use of the time-of-flight technique for neutron powder diffraction. The properties of the pulsed source make possible unusually high resolution over a wide range of d spacings, high count rates, and the ability to collect complete data at fixed scattering angles. The peak shape and other instrument characteristics can be accurately modelled, which make Rietveld refinement possible for complex structures. In this paper we briefly review the development of the Rietveld method for time-of-flight diffraction data from pulsed neutron sources and discuss the latest developments in high resolution instrumentation and advanced Rietveld analysis methods. 50 refs., 12 figs., 14 tabs

  11. Residual stress measurement of the jacket material for ITER coil by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Yoshinori [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    Nickel-Iron based super alloy INCOLOY 908 is used for the jacket of a central solenoid coil (CS coil) of the International Thermonuclear Experimental Reactor (ITER). INCOLOY 908, however, has a possibility of fracture due to Stress Accelerated Grain Boundary Oxidation (SAGBO) under a tensile residual stress beyond 200MPa. Therefore it is necessary to measure the residual stress of the jacket to avoid SAGBO. We performed residual stress measurement of the jacket by neutron diffraction using the neutron diffractometer for residual stress analysis (RESA) installed at JRR-3M in JAERI. A sample depth dependence of internal strain was obtained from the (111) plane spacing. A residual stress distribution was calculated from the strain using Young`s modulus and Poisson`s ratio that were evaluated by a tensile test with neutron diffraction. The result shows that the tensile residual stress exceeds 200MPa of the SAGBO condition in some regions inside the jacket. (author)

  12. Simultaneous thermal neutron decay time and porosity logging system

    International Nuclear Information System (INIS)

    Shultz, W.E.

    1980-01-01

    A method for simultaneously determining the porosity and thermal neutron capture cross-section of earth formations in the vicinity of a well borehole is claimed. It comprises the following steps: passing a well tool into a cased well borehole. The tool has a pulsed source of fast neutrons, a combination fast neutron and gamma ray detector and an epithermal neutron detector; repetitively irradiating the earth formations in the vicinity of the borehole with bursts of fast neutrons; detecting the fast neutron and epithermal neutron populations in the borehole (during the neutron bursts) and generating first and second measurement signals; detecting for second and third time intervals during the time between the neutron bursts, the gamma radiation present in the borehole due to the capture of thermalized neutrons by the nuclei of elements comprising the earth formations and generating third and fourth measurement signals; and combining the first and second measurement signals according to a predetermined relationship to derive an indication of the porosity of the earth formations and combining the third and fourth measurement signals to derive an indication of the thermal neutron capture cross-section of the earth formations

  13. Development of high flux thermal neutron generator for neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Vainionpaa, Jaakko H., E-mail: hannes@adelphitech.com [Adelphi Technology, 2003 E Bayshore Rd, Redwood City, CA 94063 (United States); Chen, Allan X.; Piestrup, Melvin A.; Gary, Charles K. [Adelphi Technology, 2003 E Bayshore Rd, Redwood City, CA 94063 (United States); Jones, Glenn [G& J Jones Enterprice, 7486 Brighton Ct, Dublin, CA 94568 (United States); Pantell, Richard H. [Department of Electrical Engineering, Stanford University, Stanford, CA (United States)

    2015-05-01

    The new model DD110MB neutron generator from Adelphi Technology produces thermal (<0.5 eV) neutron flux that is normally achieved in a nuclear reactor or larger accelerator based systems. Thermal neutron fluxes of 3–5 · 10{sup 7} n/cm{sup 2}/s are measured. This flux is achieved using four ion beams arranged concentrically around a target chamber containing a compact moderator with a central sample cylinder. Fast neutron yield of ∼2 · 10{sup 10} n/s is created at the titanium surface of the target chamber. The thickness and material of the moderator is selected to maximize the thermal neutron flux at the center. The 2.5 MeV neutrons are quickly thermalized to energies below 0.5 eV and concentrated at the sample cylinder. The maximum flux of thermal neutrons at the target is achieved when approximately half of the neutrons at the sample area are thermalized. In this paper we present simulation results used to characterize performance of the neutron generator. The neutron flux can be used for neutron activation analysis (NAA) prompt gamma neutron activation analysis (PGNAA) for determining the concentrations of elements in many materials. Another envisioned use of the generator is production of radioactive isotopes. DD110MB is small enough for modest-sized laboratories and universities. Compared to nuclear reactors the DD110MB produces comparable thermal flux but provides reduced administrative and safety requirements and it can be run in pulsed mode, which is beneficial in many neutron activation techniques.

  14. Evaluation of residual stresses in composite materials by using neutron diffraction; study of elasto-plasticity; Etude des composites a matrice metallique par la technique de la diffraction de neutrons: analyse du comportement elastoplastique et evaluation des contraintes residuelles

    Energy Technology Data Exchange (ETDEWEB)

    Levy-Tubiana, R

    1999-11-05

    This work deals with the study of Metal Matrix Composites (MMC) using neutrons diffraction method and the analysis of the elastoplastic behavior in such materials. First, we evaluated macro-stresses in aluminium MMC reinforced with 17%vol. of SiC particles. One of the analyzed sample has been 4 point bending deformed, measurements have been performed after relaxation. The difference between the coefficients of thermal expansion constrains the matrix to be in tensile state and the particles in compressive state in the sample which has not be deformed. In the sample deformed, the MMC response is predicted by the science of Resistance Materials applied to a bent bar. We assume that macro-stresses are the sum of stresses with different origins (elastic, plastic, thermal mismatch): elastic mismatch is evaluated by Eshelby model and we determined micro-stresses in the unbent bar: they are equivalent and constant along width direction. For the bent bar, we observe relaxation of thermal stresses in the surface region. Theses results are confirmed by measurements of tensile/compressive sample using neutrons diffraction method. We also observed the influence of mechanical and thermal treatment on such MMC: the shear stress (established by the auto-coherent model) depends only on the way of cooling. Finally, a study was performed on titanium MMC for SNECMA on rotor beings used in the gas turbine engine industry. Evolution of stresses between felloe and boring is confirmed by a finite elements modeling and they are the first experimental results in this application. (author)

  15. Performance of a thermal neutron radiographic system using imaging plates

    International Nuclear Information System (INIS)

    Silvani, Maria Ines; Almeida, Gevaldo L. de; Furieri, Rosanne; Lopes, Ricardo T.

    2009-01-01

    A performance evaluation of a neutron radiographic system equipped with a thermal neutron sensitive imaging plate has been undertaken. It includes the assessment of spatial resolution, linearity, dynamic range and the response to exposure time, as well as a comparison of these parameters with the equivalent ones for neutron radiography employing conventional films and a gadolinium foil as converter. The evaluation and comparison between the radiographic systems have been performed at the Instituto de Engenharia Nuclear - CNEN, using the Argonauta Reactor as source of thermal neutrons and a commercially available imaging plate reader. (author)

  16. Visualization of time-of-flight neutron diffraction data

    International Nuclear Information System (INIS)

    Mikkelson, D.J.; Price, D.L.; Worlton, T.G.

    1995-01-01

    The glass, liquids and amorphous materials diffractometer (GLAD) is a new instrument at the intense pulsed neutron source (IPNS) at Argonne National Laboratory. The GLAD currently has 218 linear position sensitive detectors arranged in five banks. Raw data collected from the instrument are typically split into 1000-1500 angular groups each of which contains approximately 2000 time channels. In order to obtain a meaningful overview of such a large amount of data, an interactive system to view the data has been designed. The system was implemented in C using the graphical kernel system (GKS) for portability.The system treats data from each bank of detectors as a three-dimensional data set with detector number, position along detector and time of flight as the three coordinate axes. The software then slices the data parallel to any of the coordinate planes and displays the slices as images. This approach has helped with the detailed analysis of detector electronics, verification of instrument calibration and resolution determination. In addition, it has helped to identify low-level background signals and provided insight into the overall operation of the instrument. ((orig.))

  17. Neutron Diffraction Study On Gamma To Alpha Phase Transition In Ce0.9th0.1 Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lashley, Jason C1 [Los Alamos National Laboratory; Heffner, Robert H [Los Alamos National Laboratory; Llobet, A [Los Alamos National Laboratory; Darling, T W [U OF NEVADA; Jeong, I K [PUSAN NATL UNIV

    2008-01-01

    Comprehensive neutron diffraction measurements were performed to study the isostructural {gamma} {leftrightarrow} {alpha} phase transition in Ce{sub 0.9}Th{sub 0.1} alloy. Using Rietveld refinements, we obtained lattice and thermal parameters as a function of temperature. From the temperature slope of the thermal parameters, we determined Debye temperatures {Theta}{sup {gamma}}{sub D} = 133(1) K and {Theta}{sup {alpha}}{sub D} = 140(1) K for the {gamma} phase and the {alpha} phase, respectively. This result implies that the vibrational entropy change is not significant at the {gamma} {leftrightarrow} {alpha} transition, contrary to that from elemental Cerium [Phys. Rev. Lett. 92, 105702, 2004].

  18. Neutron diffraction studies on ordered and disordered materials

    International Nuclear Information System (INIS)

    Krishna, P.S.R

    2016-01-01

    Knowledge of the symmetry and distribution of atoms in the unit cell and the bonding between atoms is the key point for understanding, designing and manipulating chemical behavior or physical properties of novel materials for technological applications. This could be achieved using diffraction techniques. At the Dhruva national facility, BARC, Mumbai, a Powder diffractometer (PD2) and a High-Q diffractometer (HQD) are in operation for more than 2 decades. PD2 and HQD are equipped with banks of 5 and 10 position sensitive detectors (PSD) respectively, to cover the Q-ranges 9.4 Å -1 and 15 Å -1 respectively. The resolutions (Δd/d) of these instruments are 0.8% (λ = 1.24 Å) and 2.5% (λ = 0.78 Å). We report about the studies of changes in the long range order in crystalline materials as a function of temperature and/or composition as well as short and intermediate range orders studied in amorphous materials on these diffractometers in recent years. PD2 has been extensively used in the structural/phase transition studies of ferroics, multiferroics, nanoferrites along with magnetic structure determinations. On the other hand, HQD has been extensively used to understand the short and intermediate range order in network glasses like chalcogenides, H-bonded alcohols, Telluride glasses etc. We will be discussing the recent structural results obtained on many of these crystalline systems, glasses and molecular fluids on both of these diffractometers. (author)

  19. Simultaneous thermal neutron decay time and porosity logging system

    International Nuclear Information System (INIS)

    Schultz, W.E.; Smith, H.D.; Smith, M.P.

    1980-01-01

    An improved method and apparatus are described for simultaneously measuring the porosity and thermal neutron capture cross section of earth formations in situ in the vicinity of a well borehole using pulsed neutron well logging techniques. The logging tool which is moved through the borehole consists of a 14 MeV pulsed neutron source, an epithermal neutron detector and a combination gamma ray and fast neutron detector. The associated gating systems, counters and combined digital computer are sited above ground. (U.K.)

  20. Fundamentals and applications of neutron diffraction. Applications 7. Crystal structure analysis of fuel cell materials by means of neutron diffractometry

    International Nuclear Information System (INIS)

    Itoh, Takanori

    2010-01-01

    Perovskite oxides, which have 'A' atoms of an alkaline earth metal and/or a rare earth metal and 'B' atoms of a transition metal, have considerable potential for use in electrochemical devices such as cathodes of solid oxide fuel cells (SOFC), oxygen pumps, oxygen sensors, catalysts, and other devices such as oxygen separation membranes. The oxygen ion behavior is studied with relation performance of electrochemical devices. I have analyzed the crystal structure of SOFC materials by neutron diffraction. Using the Rietveld refinement technique, I showed that the O1(4c) and O2(8d) sites in a perovskite oxide of SOFC cathode material has different oxygen site occupancies. Furthermore, oxygen diffusion behavior is associated with temperature dependence of oxygen anisotropic atomic displacement parameters. The maximum entropy method (MEM) analysis of neutron diffraction measurements revealed nuclear scattering length distribution at high temperature by three-dimensional images in detail, therefore 1 found oxygen diffusion pass and new proton site in SOFC materials. From these results, neutron diffraction is confirmed to be very useful tool for the study of light element behavior in fuel cell materials. (author)

  1. Neutron capture therapy with thermal neutrons at IRT MIFI

    International Nuclear Information System (INIS)

    Zajtsev, K.N.; Portnov, A.A.; Savkin, V.A.; Kulakov, V.N.; Khokhlov, V.F.; Shejno, I.N.; Vajnson, A.A.; Kozlovskaya, N.G.; Meshcherikova, V.V.; Mitin, V.N.; Yarmonenko, S.P.

    2001-01-01

    Combined preclinical investigations into neutron capture therapy are conducted. Malignant melanoma was adopted as the line of investigation; boron-containing and gadolinium-containing preparations were used during the neutron capture therapy working off. Preparations produce secondary varying radiations when used in tumor. Dogs with spontaneous melanoma were used for the experiments. Procedures for the irradiation of dogs by neutron beam as the stage before use for the treatment of oncology patients were finished off; efficiency of neutron beam influence on normal tissues during the irradiation of dogs with melanoma (and without it) in antitumor and side effect sense was estimated [ru

  2. 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

  3. 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.

  4. Characteristics of thermal neutron calibration fields using a graphite pile

    International Nuclear Information System (INIS)

    Uchita, Yoshiaki; Saegusa, Jun; Kajimoto, Yoichi; Tanimura, Yoshihiko; Shimizu, Shigeru; Yoshizawa, Michio

    2005-03-01

    The Facility of Radiation Standards of Japan Atomic Energy Research Institute is equipped with thermal neutron fields for calibrating area and personal neutron dosemeters. The fields use moderated neutrons leaked from a graphite pile in which radionuclide sources are placed. In January 2003, we have renewed the pile with some modifications in its size. In accordance with the renewal, we measured and calculated thermal neutron fluence rates, neutron energy distributions and angular distributions of the fields. The thermal neutron fluence rates of the ''inside-pile fields'' and the outside-pile fields'' were determined by the gold foil activation method. The neutron energy distributions of the outside-pile fields were also measured with the Bonner multi-sphere spectrometer system. The contributions of epithermal and fast neutrons to the total dose-equivalents were 9% in the southern outside-pile field and 12% in the western outside-pile field. The personal dose-equivalents, H p,slab (10, α), in the outside-pile fields are evaluated by considering the calculated angular distributions of incoming neutrons. The H p,slab (10, α) was found to be about 40% higher than the value in assuming the unidirectional neutron between the pile and the test point. (author)

  5. Non-destructive bulk analysis of the Buggenum sword by neutron resonance capture analysis and neutron diffraction

    International Nuclear Information System (INIS)

    Postma, H.; Clarijs, M.; Borella, A.; Schillebeeckx, P.; Kamermans, H.

    2010-01-01

    Two neutron based techniques, neutron resonance capture analysis (NRCA) and time-of-flight neutron-diffraction (TOF-ND) have been used to determine the elemental composition and structure of a precious and very well preserved all-metal sword from the Bronze Age. This Buggenum sword was on loan from the National Museum of Antiquities (NMA) in Leiden (NL). NRCA and TOF-ND experiments have been carried out at a number of more or less identical positions of the sword. The tin-bronze ratio and the relative amounts of some minor elements (Sb, As, Ag, In) have been determined. The results of neutron diffraction measurements showed considerable tin-segregation, and clear indications of hardening on the edges of the blade. In addition, radiographs using Bremsstrahlung revealed the construction of the hilt-blade connection. The work was carried out at the EC Joint Research Centre IRMM in Geel (B) and at the ISIS facility of the Rutherford Appleton Laboratory (UK). (author)

  6. Neutron diffraction measurement of residual stress in NPP construction materials

    International Nuclear Information System (INIS)

    Hinca, R.; Bokuchava, G.

    2000-01-01

    The aim of the investigation is to study the level of residual stresses induced by the surfacing in the weld deposit zone and in the base metal, where considerable thermal gradients are present. Surfacing high-nickel filler on an austenitic base metal is one of techniques in repair of primary collector the primary circuit of nuclear power plant type VVER. The repair technology was developed at Welding Research Institute Bratislava. Measurements of residual stresses in the weld overlay and the base metal are necessary for approving the mechanical analysis and verifying of residual stresses determination on welded material by numerical weld g computer simulation. Investigations of residual stresses are important for developing optimal welding techniques. (authors)

  7. Stereoscopic radiographic images with thermal neutrons

    International Nuclear Information System (INIS)

    Silvani, M.I.; Almeida, G.L.; Rogers, J.D.; Lopes, R.T.

    2011-01-01

    Spatial structure of an object can be perceived by the stereoscopic vision provided by eyes or by the parallax produced by movement of the object with regard to the observer. For an opaque object, a technique to render it transparent should be used, in order to make visible the spatial distribution of its inner structure, for any of the two approaches used. In this work, a beam of thermal neutrons at the main port of the Argonauta research reactor of the Instituto de Engenharia Nuclear in Rio de Janeiro/Brazil has been used as radiation to render the inspected objects partially transparent. A neutron sensitive Imaging Plate has been employed as a detector and after exposure it has been developed by a reader using a 0.5 μm laser beam, which defines the finest achievable spatial resolution of the acquired digital image. This image, a radiographic attenuation map of the object, does not represent any specific cross-section but a convoluted projection for each specific attitude of the object with regard to the detector. After taking two of these projections at different object attitudes, they are properly processed and the final image is viewed by a red and green eyeglass. For monochromatic images this processing involves transformation of black and white radiographies into red and white and green and white ones, which are afterwards merged to yield a single image. All the processes are carried out with the software ImageJ. Divergence of the neutron beam unfortunately spoils both spatial and contrast resolutions, which become poorer as object-detector distance increases. Therefore, in order to evaluate the range of spatial resolution corresponding to the 3D image being observed, a curve expressing spatial resolution against object-detector gap has been deduced from the Modulation Transfer Functions experimentally. Typical exposure times, under a reactor power of 170 W, were 6 min for both quantitative and qualitative measurements. In spite of its intrinsic constraints

  8. Stereoscopic radiographic images with thermal neutrons

    Science.gov (United States)

    Silvani, M. I.; Almeida, G. L.; Rogers, J. D.; Lopes, R. T.

    2011-10-01

    Spatial structure of an object can be perceived by the stereoscopic vision provided by eyes or by the parallax produced by movement of the object with regard to the observer. For an opaque object, a technique to render it transparent should be used, in order to make visible the spatial distribution of its inner structure, for any of the two approaches used. In this work, a beam of thermal neutrons at the main port of the Argonauta research reactor of the Instituto de Engenharia Nuclear in Rio de Janeiro/Brazil has been used as radiation to render the inspected objects partially transparent. A neutron sensitive Imaging Plate has been employed as a detector and after exposure it has been developed by a reader using a 0.5 μm laser beam, which defines the finest achievable spatial resolution of the acquired digital image. This image, a radiographic attenuation map of the object, does not represent any specific cross-section but a convoluted projection for each specific attitude of the object with regard to the detector. After taking two of these projections at different object attitudes, they are properly processed and the final image is viewed by a red and green eyeglass. For monochromatic images this processing involves transformation of black and white radiographies into red and white and green and white ones, which are afterwards merged to yield a single image. All the processes are carried out with the software ImageJ. Divergence of the neutron beam unfortunately spoils both spatial and contrast resolutions, which become poorer as object-detector distance increases. Therefore, in order to evaluate the range of spatial resolution corresponding to the 3D image being observed, a curve expressing spatial resolution against object-detector gap has been deduced from the Modulation Transfer Functions experimentally. Typical exposure times, under a reactor power of 170 W, were 6 min for both quantitative and qualitative measurements. In spite of its intrinsic constraints

  9. Study of quartz-glass using Roentgen- and neutron-diffraction

    International Nuclear Information System (INIS)

    Sikkenk, P.J.

    1988-08-01

    An X-ray diffraction measurement, with wavelength 0.0711 nm, is made of a vitreous silica to kappa of 200nm -1 . (faculty of materials science) A second X-ray diffraction measurement has been executed (National Laboratory Oak Ridge). For this research we also used neutron diffraction measurement (IRI), with wavelength 0.085 nm of a vitreous silica to kappa of 132 nm -1 . The intermolecular scattering functions derived from the X-ray measurements and neutron measurements by omitting the intramolecular scattering contribution. A theoretical model for the structure of vitreous silica is used, derived from a mixture of Si en SiO-4 units. The partial scattering functions i-S-i---S-i is determined with help of the model and the intermolecular X-ray scattering functions and intermolecular neutron scattering functions and intermolecular neutron scatteirng functions. The fouriertransform of the partial scattering function i-S-i---S-i leads to the partial radial correlation function. When this partial radial correlation function is compared to a correlation function directly obtained by the intermolecular scattering function, a considerable increase of the resolution is observed in the partial correlation function if r > 0.29 nm and r < 0.45 nm. (author). 16 refs.; 30 figs.; 9 tabs

  10. Neutron diffraction analysis of the structure of rod photoreceptor membranes in intact retinas

    Energy Technology Data Exchange (ETDEWEB)

    Yaeger, M; Schoenborn, B; Engelman, D; Moore, P; Stryer, L

    1980-01-01

    Neutron diffraction data have been collected from samples containing ten dark-adapted Rana catesbiana bullfrog retinas in 100, 80, 60, 40, and 30% D/sub 2/O Ringer's solution using a step-scanning Soller slit diffractometer. Diffraction was also recorded from retinas equilibrated in D/sub 2/O solutions with varying osmolarity. Rocking curve experiments demonstrated that the rods are disoriented in a cylindrically symmetrical fashion. Structure factor amplitudes were obtained using semi-automated curve-fitting procedures, and phases were obtained by interpreting the D/sub 2/O-H/sub 2/O and osmotic Patterson maps. In D/sub 2/O Ringer's solution the first four structure factors are -353 +- 25, 246 +- 19, 434 +- 13 and 383 +- 19. Neutron scattering density profiles were calculated to 75 A resolution using these structure factors. These neutron diffraction data are consistent with the view that the lipid bilayer is a major structural motif of the rod outer segment disc membrane. Neutron Fourier syntheses in different mixtures of D/sub 2/O and H/sub 2/O indicate that the intradisc and extradisc spaces are predominantly aqueous, consistent with the increase in the intradisc and extradisc volumes as the Ringer's solution is made more hypotomic. In isotonic Ringer's solution, the thicknesses of the intradisc and extradisc spaces are about 36 A and 160 A, respectively, and the center-to-center separation between the 50 A thick lipid bilayer is 88 A.

  11. GEM-based thermal neutron beam monitors for spallation sources

    International Nuclear Information System (INIS)

    Croci, G.; Claps, G.; Caniello, R.; Cazzaniga, C.; Grosso, G.; Murtas, F.; Tardocchi, M.; Vassallo, E.; Gorini, G.; Horstmann, C.; Kampmann, R.; Nowak, G.; Stoermer, M.

    2013-01-01

    The development of new large area and high flux thermal neutron detectors for future neutron spallation sources, like the European Spallation Source (ESS) is motivated by the problem of 3 He shortage. In the framework of the development of ESS, GEM (Gas Electron Multiplier) is one of the detector technologies that are being explored as thermal neutron sensors. A first prototype of GEM-based thermal neutron beam monitor (bGEM) has been built during 2012. The bGEM is a triple GEM gaseous detector equipped with an aluminum cathode coated by 1μm thick B 4 C layer used to convert thermal neutrons to charged particles through the 10 B(n, 7 Li)α nuclear reaction. This paper describes the results obtained by testing a bGEM detector at the ISIS spallation source on the VESUVIO beamline. Beam profiles (FWHM x =31 mm and FWHM y =36 mm), bGEM thermal neutron counting efficiency (≈1%), detector stability (3.45%) and the time-of-flight spectrum of the beam were successfully measured. This prototype represents the first step towards the development of thermal neutrons detectors with efficiency larger than 50% as alternatives to 3 He-based gaseous detectors

  12. Crystallization of porcine pancreatic elastase and a preliminary neutron diffraction experiment

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Takayoshi [Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Tamada, Taro [Molecular Structural Biology Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Imai, Keisuke [Lead Discovery Research Laboratories, Astellas Pharma Inc., 21 Miyukigaoka, Tsukuba-shi, Ibaraki 305-8585 (Japan); Kurihara, Kazuo; Ohhara, Takashi [Molecular Structural Biology Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Tada, Toshiji [Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Kuroki, Ryota, E-mail: kuroki.ryota@jaea.go.jp [Molecular Structural Biology Group, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan)

    2007-04-01

    To investigate the structural characteristics of a covalent inhibitor bound to porcine pancreatic elastase (PPE), including H atoms and hydration by water, a crystal of porcine pancreatic elastase with its inhibitor was grown to a size of 1.6 mm{sup 3} for neutron diffraction study. The crystal diffracted to 2.3 Å resolution with sufficient quality for further structure determination owing to the similar atomic scattering properties of deuterium and carbon. Porcine pancreatic elastase (PPE) resembles the attractive drug target leukocyte elastase, which has been implicated in a number of inflammatory disorders. In order to investigate the structural characteristics of a covalent inhibitor bound to PPE, including H atoms and the hydration by water, a single crystal of PPE for neutron diffraction study was grown in D{sub 2}O containing 0.2 M sodium sulfate (pD 5.0) using the sitting-drop vapour-diffusion method. The crystal was grown to a size of 1.6 mm{sup 3} by repeated macroseeding. Neutron diffraction data were collected at room temperature using a BIX-3 diffractometer at the JRR-3 research reactor of the Japan Atomic Energy Agency (JAEA). The data set was integrated and scaled to 2.3 Å resolution in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 51.2, b = 57.8, c = 75.6 Å.

  13. The magnetic structure of GdNi2B2C investigated by neutron powder diffraction

    International Nuclear Information System (INIS)

    Barcza, A.; Rotter, M.; Doerr, M.; Beuneu, B.

    2005-01-01

    Full text: The group of ReT 2 B 2 C (Re=rare earth, T=transition metal) shows a very interesting interplay between magnetism and superconductivity due to the rare earth metals. In this work the magnetism of GdNi 2 B 2 C was studied with neutron diffraction. Previous investigations with x-ray diffraction methods have determined the crystal structure as a body centered tetragonal structure (I 4/mmm). Hot neutrons were used for the diffraction experiment, because the absorption cross section of Gd is significantly smaller for short wavelengths. The investigated compound orders magnetically at TN=19.5 K, and so the experiment was carried out at two temperatures, namely 30 K and 2.2 K. The results show a incommensurate spin structure with a propagation vector of (0.55 0 0). To confirm this results additional simulations of the spin structure were done based on the Standard Model of rare earth magnetism. A neutron diffraction pattern was calculated using the McPhase program package and is compared to the experimental data. (author)

  14. Nanocrystallite characterization of milled simulated dry process fuel powders by neutron diffraction

    International Nuclear Information System (INIS)

    Ryu, Ho Jin; Kang, Kwon Ho; Moon, Je Sun; Song, Kee Chan; Choi, Yong Nam

    2003-01-01

    The nano-scale crystallite sizes of simulated spent fuel powders were measured by the neutron diffraction line broadening method in order to analyze the sintering behavior of the dry process fuel. The mixed U0 2 and fission product oxide powders were dry-milled in an attritor for 30, 60, and 120 min. The diffraction patterns of the powders were obtained by using the high resolution powder diffractometer in the HANARO research reactor. Diffraction line broadening due to crystallite size was measured using various techniques such as the Stokes' deconvolution, profile fitting methods using Cauchy function, Gaussian function, and Voigt function, and the Warren-Averbach method. The r.m.s. strain, stacking fault, twin and dislocation density were measured using the information from the diffraction pattern. The realistic crystallite size can be obtained after separation of the contribution from the non-uniform strain, stacking fault and twin

  15. Thermal neutron detectors based on complex oxide crystals

    CERN Document Server

    Ryzhikov, V; Volkov, V; Chernikov, V; Zelenskaya, O

    2002-01-01

    The ways of improvement of spectrometric quality of CWO and GSO crystals have been investigated with the aim of their application in thermal neutron detectors based on radiation capture reactions. The efficiency of the neutron detection by these crystals was measured, and the obtained data were compared with the results for sup 6 LiI(Tl) crystals. It is shown that the use of complex oxide crystals and neutron-absorption filters for spectrometry of thermal and resonance neutrons could be a promising method in combination with computer data processing. Numerical calculations are reported for spectra of gamma-quanta due to radiation capture of the neutrons. To compensate for the gamma-background lines, we used a crystal pair of heavy complex oxides with different sensitivity to neutrons.

  16. Electron diffraction patterns with thermal diffuse scattering maxima around Kikuchi lines

    International Nuclear Information System (INIS)

    Karakhanyan, R. K.; Karakhanyan, K. R.

    2011-01-01

    Transmission electron diffraction patterns of silicon with thermal diffuse maxima around Kikuchi lines, which are analogs of the maxima of thermal diffuse electron scattering around point reflections, have been recorded. Diffuse maxima are observed only around Kikuchi lines with indices that are forbidden for the silicon structure. The diffraction conditions for forming these maxima are discussed.

  17. Final Technical Report: Application of in situ Neutron Diffraction to Understand the Mechanism of Phase Transitions

    Energy Technology Data Exchange (ETDEWEB)

    Chandran, Ravi [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Metallurgical Engineering

    2018-02-09

    In this research, phase transitions in the bulk electrodes for Li-ion batteries were investigated using neutron diffraction (ND) as well as neutron imaging techniques. The objectives of this research is to design of a novel in situ electrochemical cell to obtain Rietveld refinable neutron diffraction experiments using small volume electrodes of various laboratory/research-scale electrodes intended for Li-ion batteries. This cell is also to be used to investigate the complexity of phase transitions in Li(Mg) alloy electrodes, either by diffraction or by neutron imaging, which occur under electrochemical lithiation and delithiation, and to determine aspects of phase transition that enable/limit energy storage capacity. Additional objective is to investigate the phase transitions in electrodes made of etched micro-columns of silicon and investigate the effect of particle/column size on phase transitions and nonequilibrium structures. An in situ electrochemical cell was designed successfully and was used to study the phase transitions under in-situ neutron diffraction in both the electrodes (anode/cathode) simultaneously in graphite/LiCoO2 and in graphite/LiMn2O4 cells each with two cells. The diffraction patterns fully validated the working of the in situ cell. Additional experimental were performed using the Si micro-columnar electrodes. The results revealed new lithiation phenomena, as evidenced by mosaicity formation in silicon electrode. These experiments were performed in Vulcan diffractometer at SNS, Oak Ridge National Laboratory. In parallel, the spatial distribution of Li during lithiation and delithiation processes in Li-battery electrodes were investigated. For this purpose, neutron tomographic imaging technique has been used for 3D mapping of Li distribution in bulk Li(Mg) alloy electrodes. It was possible to observe the phase boundary of Li(Mg) alloy indicating phase transition from Li-rich BCC β-phase to Li-lean

  18. The measurement of internal stress fields in weldments and around cracks using high resolution neutron diffraction

    International Nuclear Information System (INIS)

    Allen, A.J.; Hutchings, M.T.; Windsor, C.G.

    1987-01-01

    The paper describes and illustrates the capability of neutron diffraction to measure the complete internal lattice macrostrain field, and hence the stress field, within steel components and weldments arising from their fabrication. A brief outline is given of the theory of the neutron method. The experimental considerations are discussed. The method is illustrated by its application to the measurement of the stress distribution in a:- uniaxially stressed mild steel rod, a double - V test weld, a tube-plate weld, and a cracked fatigue test specimen. (U.K.)

  19. Use of neutron diffraction in determining strains in high-temperaure superconducting composites

    International Nuclear Information System (INIS)

    Hitterman, R.L.; Faber, J. Jr.; Kupperman, D.S.; Singh, J.P.; Majumdar, S.

    1990-01-01

    The Argonne Intense Pulsed Neutron Source and General Purpose Powder Diffractometer have been used to study high T c metal oxide composites composed of yttrium barium copper oxide and silver. Neutron diffraction techniques were applied to composites with 15, 20 and 30% silver content by volume. The authors have observed that after hot pressing, the 30% Ag specimens contained both orthorhombic high T c and tetragonal, non-superconducting phases near the center of the specimens but only tetragonal near the surface. The relationship of shifts in Bragg peaks to strains of the constituents is discussed

  20. Neutron thermalization and spectra; Thermalisation et spectres de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Cadilhac, M; Soule, J L; Tretiakoff, O [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The investigation of the neutron spectra in thermal reactors is taking an increasing importance due to the role played in them by Plutonium. Whatever the absorption law, it has been remarked that the scattering law in the.moderator affects the spectrum only through certain overall properties. It would thus seem possible to develop a simplified representation of this effect which would lead to a clear understanding of the phenomena, reducing at the same time the volume of numerical calculations required.. The synthetic model employed by the authors presents the advantage of reducing the determination of the spectra in an homogeneous medium to the resolution of a second order differential equation, like the Wigner-Wilkins model (monoatomic gaseous hydrogen) and the generalized heavy gas model of J. Horowitz which, incidentally, are both special cases. The model is, on the other hand, sufficiently general to allow a correct treatment of the situations met with in practice and in particular the important case where the presence of Plutonium introduces absorption resonances at low energy. Actually, the chemical or crystalline bonds of the moderator are introduced into the proposed model through two energy functions. These functions have been adjusted for the usual moderators (Graphite heavy water, light water) by means of known theoretical scattering laws. In a heterogeneous medium, the most important factor is the mean spectrum in the fuel of one cell, the knowledge of which is allowed by a generalization of the Amouyal-Benoist-Horowitz method. The proposed model lends itself particularly well to such calculations and also allows the effects of re-thermalization (for instance when the cooling system and the moderator are at different temperatures) to be treated. Finally, some examples are given of practical applications: codes for spectra and effective cross sections computations (editing of tables), codes for the treatment of neutron balance in a lattice or for the

  1. Neutron and thermal dynamics of a gaseous core fission reactor

    International Nuclear Information System (INIS)

    van Dam, H.; Kuijper, J.C.; Stekelenburg, A.J.C.; Hoogenboom, J.E.; Boersma-Klein, W.; Kistemaker, J.

    1989-01-01

    In this paper neutron kinetics and thermal dynamics of a Gaseous Core Fission Reactor with magnetical pumping are shown to have many unconventional aspects. Attention is focused on the properties of the fuel gas, the non-linear neutron kinetics and the energy balance in thermodynamical cycles

  2. Monte Carlo calculations of neutron thermalization in a heterogeneous system

    Energy Technology Data Exchange (ETDEWEB)

    Hoegberg, T

    1959-07-15

    The slowing down of neutrons in a heterogeneous system (a slab geometry) of uranium and heavy water has been investigated by Monte Carlo methods. Effects on the neutron spectrum due to the thermal motions of the scattering and absorbing atoms are taken into account. It has been assumed that the speed distribution of the moderator atoms are Maxwell-Boltzmann in character.

  3. Determination of average activating thermal neutron flux in bulk samples

    International Nuclear Information System (INIS)

    Doczi, R.; Csikai, J.; Doczi, R.; Csikai, J.; Hassan, F. M.; Ali, M.A.

    2004-01-01

    A previous method used for the determination of the average neutron flux within bulky samples has been applied for the measurements of hydrogen contents of different samples. An analytical function is given for the description of the correlation between the activity of Dy foils and the hydrogen concentrations. Results obtained by the activation and the thermal neutron reflection methods are compared

  4. Calculation of the neutron parameters of fast thermal reactor

    International Nuclear Information System (INIS)

    Kukuleanu, V.; Mocioiu, D.; Drutse, E.; Konstantinesku, E.

    1975-01-01

    The system of neutron calculation for fast reactors is given. This system was used for estimation of physical parameters of fast thermal reactors investigated. The results obtained and different specific problems of the reactors of this type are described. (author)

  5. Real Structure and Resudal Stresses in Advanced Welds Determined by X-ray and Neutron Diffraction

    Czech Academy of Sciences Publication Activity Database

    Trojan, K.; Hervoches, Charles; Ganev, N.; Mikula, Pavol; Čapek, J.

    2017-01-01

    Roč. 9, SEP (2017), s. 32-38 E-ISSN 2336-5382 R&D Projects: GA MŠk LM2015056; GA ČR GB14-36566G Institutional support: RVO:61389005 Keywords : laser and MAG welding * residual stresses * X-ray diffraction * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) https://ojs.cvut.cz/ojs/index.php/APP/article/view/4401/4298

  6. Influence of Al on the magnetic properties of TmCo{sub 4}Al compound, a magnetic and neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Laslo, A. [CNRS, Inst. Néel, F-38042 Grenoble (France); Univ. Grenoble Alpes, Inst. Néel, F-38042 Grenoble (France); Babes-Bolyai University, Faculty of Physics, 400084 Cluj-Napoca (Romania); Pop, V. [Babes-Bolyai University, Faculty of Physics, 400084 Cluj-Napoca (Romania); Isnard, O. [CNRS, Inst. Néel, F-38042 Grenoble (France); Univ. Grenoble Alpes, Inst. Néel, F-38042 Grenoble (France)

    2015-03-25

    Highlights: • The existence of a compensation temperature is found for TmCo{sub 4}Al. • The crystal structure and its thermal evolution are analysed by X-ray and neutron diffraction. • The ferrimagnetic magnetic structure of TmCo{sub 4}Al is established. • Magnetic properties are determined. • Significant coercivity is reported for TmCo{sub 4}Al. - Abstract: The structural and magnetic properties of the TmCo{sub 4}Al compound are presented as deduced from magnetic measurements, X-ray and neutron powder diffraction. The crystal structure is obtained in the light of Rietveld refinement of the neutron powder diffraction pattern. The symmetry of the CaCu{sub 5} structure is preserved and the Al atom is found to substitute the Co one exclusively on the 3g atomic position. Thermal expansion of the crystal lattice is reported, the temperature variation occurring mostly along the basal hexagonal plane. This compound exhibits a ferrimagnetic structure, the Tm and Co magnetic moments being coupled antiparallel. An ordering temperature of 511 K is found. The thermal dependence of the Tm magnetic moment is obtained down to 4 K. A compensation of the two sublattice magnetization is found at 75 K, a feature induced by the Al for Co substitution and not observed in the corresponding TmCo{sub 5} compound. Magnetization curves reveal large coercivity values at low temperature such as 2.48 T at 2 K.

  7. 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)

  8. The determination of thermal neutron cross section of 81Br

    International Nuclear Information System (INIS)

    Kovacs, Luciana; Zamboni, Cibele B.; Dalaqua Junior, Leonardo

    2009-01-01

    In this investigation several standard materials were used to determine the thermal neutron cross section of 81 Br. This nuclear parameter is an important data to perform several quantitative investigations, mainly in medical area. In other to confirm and to reduce the uncertainty, a new measurement was preformed using thermal neutron at IEA-R1 nuclear reactor of IPEN/CNEN-SP. The result obtained is compatible with the tabulated value and present small uncertainly. (author)

  9. Thermal neutron capture cross sections of tellurium isotopes

    International Nuclear Information System (INIS)

    Tomandl, I.; Honzatko, J.; Egidy, T. von; Wirth, H.-F.; Belgya, T.; Lakatos, M.; Szentmiklosi, L.; Revay, Zs.; Molnar, G.L.; Firestone, R.B.; Bondarenko, V.

    2003-01-01

    New values for thermal neutron capture cross sections of the tellurium isotopes 122 Te, 124 Te, 125 Te, 126 Te, 128 Te, and 130 Te are reported. These values are based on a combination of newly determined partial γ-ray cross sections obtained from experiments on targets contained natural Te and γ intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given

  10. Thermal neutron capture cross sections of tellurium isotopes

    International Nuclear Information System (INIS)

    Tomandl, I.; Honzatko, J.; Egidy, T. von; Wirth, H.-F.; Belgya, T.; Lakatos, M.; Szentmiklosi, L.; Revay, Zs.; Molnar, G.L.; Firestone, R.B.; Bondarenko, V.

    2004-01-01

    New values for thermal neutron capture cross sections of the tellurium isotopes 122Te, 124Te, 125Te, 126Te, 128Te, and 130Te are reported. These values are based on a combination of newly determined partial g-ray cross sections obtained from experiments on targets contained natural Te and gamma intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given

  11. Thermal neutron capture cross sections of tellurium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Tomandl, I.; Honzatko, J.; von Egidy, T.; Wirth, H.-F.; Belgya, T.; Lakatos, M.; Szentmiklosi, L.; Revay, Zs.; Molnar, G.L.; Firestone, R.B.; Bondarenko, V.

    2004-03-01

    New values for thermal neutron capture cross sections of the tellurium isotopes 122Te, 124Te, 125Te, 126Te, 128Te, and 130Te are reported. These values are based on a combination of newly determined partial g-ray cross sections obtained from experiments on targets contained natural Te and gamma intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given.

  12. Neutron powder diffraction and theory-aided structure refinement of rubidium and cesium ureate

    Energy Technology Data Exchange (ETDEWEB)

    Sterri, Kjersti B.; Deringer, Volker L.; Houben, Andreas; Jacobs, Philipp [RWTH Aachen Univ. (Germany). Inst. of Inorganic Chemistry; Kumar, Chogondahalli M.N. [Forschungszentrum Juelich GmbH, Juelich Centre for Neutron Science (JCNS), Outstation at SNS, Oak Ridge National Laboratory, Oak Ridge, TN (United States); Oak Ridge National Laboratory, TN (United States). Chemical and Engineering Materials Div.; Dronskowski, Richard [RWTH Aachen Univ. (Germany). Inst. of Inorganic Chemistry; RWTH Aachen Univ. (Germany). Juelich-Aachen Research Alliance (JARA-HPC)

    2016-08-01

    Urea (CN{sub 2}H{sub 4}O) is a fundamental biomolecule whose derivatives are abundant throughout chemistry. Among the latter, rubidium ureate (RbCN{sub 2}H{sub 3}O) and its cesium analog (CsCN{sub 2}H{sub 3}O) have been described only very recently and form the first structurally characterized salts of deprotonated urea. Here, we report on a neutron diffraction study on the aforementioned alkaline-metal ureates, which affords the positions for all hydrogen atoms (including full anisotropic displacement tensors) and thus allows us to gain fundamental insights into the hydrogen-bonding networks in the title compounds. The structure refinements of the experimental neutron data proceeded successfully using starting parameters from ab initio simulations of atomic positions and anisotropic displacement parameters. Such joint experimental-theoretical refinement procedures promise significant practical potential in cases where complex solids (organic, organometallic, framework materials) are studied by powder diffraction.

  13. A time-of-flight spectrometer for neutron diffraction under high pressure or at high temperature

    International Nuclear Information System (INIS)

    Roult, G.; Buevoz, J.L.

    1975-01-01

    For high pressure neutron diffraction studies (40 kilobars) the sample is placed in a very thick cell. In order to allow the neutron beam to go through the cell loosing as little intensity as possible, the inner part is kept solid while the external part has some windows facing the incident and reflected beam. The window dimensions are small (a few millimeters wide and a few centimeters long). There are two alternatives: to have the window either in a perpendicular plane or in a plane parallel to the axis. In the first case a fixed wavelength spectrometer can be used but the sample is small and the contribution of the cell to the diffraction pattern is relatively great. In the second case samples can be something like ten times greater and the cell contribution can be eliminated but a fixed wavelength spectrometer cannot be used. Thus the time-of-flight method is very convenient. The second alternative was chosen

  14. Neutron-diffraction measurement of residual stresses in Al-Cu cold-cut welding

    CERN Document Server

    Fiori, F

    2002-01-01

    Usually, when it is necessary to join different materials with a large difference in their melting points, welding should be avoided. To overcome this problem we designed and built a device to obtain cold-cut welding, which is able to strongly decrease oxidation problems of the surfaces to be welded. Thanks to this device it is possible to achieve good joining between different pairs of materials (Al-Ti, Cu-Al, Cu-Al alloys) without reaching the material melting point. The mechanical and microstructural characterisation of the joining and the validation of its quality were obtained using several experimental methods. In particular, in this work neutron-diffraction experiments for the evaluation of residual stresses in Cu-Al junctions are described, carried out at the G5.2 diffractometer of LLB, Saclay. Neutron-diffraction results are presented and related to other experimental tests such as microstructural characterisation (through optical and scanning electron microscopy) and mechanical characterisation (ten...

  15. Neutron diffraction study of carbontetrachloride, siliciumtetrachloride, titaniumtetrachloride, and tintetrachloride in the liquid state at 295 K

    International Nuclear Information System (INIS)

    Tricht, J.B. van

    1977-01-01

    Neutron diffraction data on the molecular liquids CCl 4 , SiCl 4 , TiCl 4 , and sSnCl 4 have been collected in an interval of the scattering parameter, kappa = 4πsintheta/lambda, extending from 0.4 A -1 to 13.3 A -1 . The neutron wavelength was 0.878 A. The statistical accuracy of the data was better than 0.25 percent, and for titanium and tin tetrachloride a factor of two better. The intermolecular contributions to the diffracted intensity is dealt with in two ways: first a comparison in kappa- and in r-space between the experimental scattering and the corresponding distribution calculated from a model of randomly oriented molecules consisting of hard spheres. Furthermore, the regions in kappa- and in r-space can be identified where positional and where orientational correlations are predominent

  16. 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.

  17. Deformation behavior of Mg-alloy-based composites at different temperatures studied by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Gergely [Department of Metal Physics, Charles University, Ke Karlovu, 5, CZ-121 16 Prague (Czech Republic); Nuclear Physics Institute, v. v. i., 250 68 Řež (Czech Republic); Máthis, Kristian [Department of Metal Physics, Charles University, Ke Karlovu, 5, CZ-121 16 Prague (Czech Republic); Pilch, Ján [Nuclear Physics Institute, v. v. i., 250 68 Řež (Czech Republic); Minárik, Peter [Department of Metal Physics, Charles University, Ke Karlovu, 5, CZ-121 16 Prague (Czech Republic); Lukáš, Petr [Nuclear Physics Institute, v. v. i., 250 68 Řež (Czech Republic); Vinogradov, Alexei, E-mail: alexei.vinogradov@ntnu.no [Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology - NTNU, Trondheim N-7491 (Norway); Institute of Advanced Technologies, Togliatti State University, 445020 (Russian Federation)

    2017-02-08

    The influence of the reinforcement short Saffil fibers on the deformation behavior of Mg-Al-Ca alloy-based composite with two different fiber plane orientations is investigated and clarified using in-situ neutron diffraction at room and elevated temperatures. The measured lattice strain evolution points to a more efficient reinforcing effect of fibers at parallel fiber plane orientation, which decreases at elevated temperature. A significant decrement of compressive lattice strain was incidentally observed in the matrix in the direction of load axis when deformation due to the elevated temperature occurred. Electron microscopy revealed the influence of the temperature and fiber orientation on fiber cracking. The EBSD observations corroborated neutron diffraction results highlighting significant twin growth at elevated testing temperatures.

  18. X – ray and neutron diffraction of TiAl alloys

    International Nuclear Information System (INIS)

    Valkov, Stefan; Petrov, Peter; Neov, Dimitar; Beskrovny, Anatoly; Kozlenko, Denis

    2015-01-01

    TiAl alloys were prepared by electron beam hybrid method. Composite Ti-Al film, from composite target, was deposited on Ti substrate by electron beam evaporation, followed by electron beam treatment with scanning electron beam. Experiments were made using Leybold Heraus (EWS 300/ 15 - 60) with the following technological parameters : accelerating voltage U = 60kV; beam current I=40 mA, speed of movement of specimens V=5 cm/s, current of the focusing lens If =512mA, specimen distance D0 = 38cm. X- ray and neutron diffraction methods were used to determine the phase composition on the surface and at the volume, respectively. Time of flight neutron diffraction study of TiAl specimens was performed on DN-2 diffractometer at fast pulsed IBR-2 reactor in FLNP JINR (Dubna, Russia).We found that intermetallic TiAl phases were successfully obtained on the surface, as well as in the volume.

  19. Neutron diffraction study of the β1-β2 transformation in Ta2D

    International Nuclear Information System (INIS)

    Kaneko, H.; Kajitani, T.; Hirabayashi, M.

    1984-01-01

    The β 1 -β 2 phase transformation in Ta 2 D was studied by neutron diffraction using the pulsed source at the Tohoku Linac and the Intense Pulsed Neutron Source, Argonne National Laboratory. It was found that the hhO reflections almost disappear in the β 2 phase, whereas the 00l reflections are the same as those in the β 1 phase. The diffraction data show that the β 2 phase has an orthorhombic unit cell which is identical with that of the β 1 phase and contains four tantalum and two deuterium atoms in a volume which is approximately 2sup(1/2) X 1 X 2sup(1/2) that of the b.c.c. host lattice. The deuterium atoms fractionally occupy the tetrahedral sites in alternate (002)sub(orth) planes. (Auth.)

  20. A flow-through hydrothermal cell for in situ neutron diffraction studies of phase transformations

    International Nuclear Information System (INIS)

    O'Neill, Brian; Tenailleau, Christophe; Nogthai, Yung; Studer, Andrew; Brugger, Joel; Pring, Allan

    2006-01-01

    A flow-through hydrothermal cell for the in situ neutron diffraction study of crystallisation and phase transitions has been developed. It can be used for kinetic studies on materials that exhibit structural transformations under hydrothermal conditions. It is specifically designed for use on the medium-resolution powder diffractometer (MRPD) at ANSTO, Lucas Heights, Sydney. But it is planned to adapt the design for the Polaris beamline at ISIS and the new high-intensity powder diffractometer (Wombat) at the new Australian reactor Opal. The cell will operate in a flow-through mode over the temperature range from 25-300 deg. C and up to pressures of 100 bar. The first results of a successful transformation of pentlandite (Fe,Ni) 9 S 8 to violarite (Fe,Ni) 3 S 4 under mild conditions (pH∼4) at 120 deg. C and 3 bar using in situ neutron diffraction measurements are presented

  1. Determination of the hexagonal network parameters of the quartz β using neutron multiple diffraction

    International Nuclear Information System (INIS)

    Campos, L.C.; Parente, C.B.R.; Mazzocchi, V.L.; Helene, O.

    2000-01-01

    In this work, neutron multiple diffraction is employed for the determination of the parameters a and c of the β-quartz hexagonal cell. This crystalline phase of silica (SiO 2 ) occurs in temperatures between ca. 846 and 1143 K. A β-quartz neutron multiple diffraction pattern has been used in the determinations. This pattern was obtained with a natural quartz single crystal heated to 1003 K. During the indexing of the pattern it was verified that most of the pairs of secondary reflections, which are responsible for the formation of peaks, could be classified as 'good for the determination of a' or 'good for the determination of c'. With this classification, it became possible to employ an iterative method for the determination of both parameters. After 8 cycles of iteration the values found for the parameters were a = 4.9964 +- 0.0018 and c = 5.46268 +- 0.00052 A. (author)

  2. 40-Tesla pulsed-field cryomagnet for single crystal neutron diffraction

    Science.gov (United States)

    Duc, F.; Tonon, X.; Billette, J.; Rollet, B.; Knafo, W.; Bourdarot, F.; Béard, J.; Mantegazza, F.; Longuet, B.; Lorenzo, J. E.; Lelièvre-Berna, E.; Frings, P.; Regnault, L.-P.

    2018-05-01

    We present the first long-duration and high duty cycle 40-T pulsed-field cryomagnet addressed to single crystal neutron diffraction experiments at temperatures down to 2 K. The magnet produces a horizontal field in a bi-conical geometry, ±15° and ±30° upstream and downstream of the sample, respectively. Using a 1.15 MJ mobile generator, magnetic field pulses of 100 ms length are generated in the magnet, with a rise time of 23 ms and a repetition rate of 6-7 pulses per hour at 40 T. The setup was validated for neutron diffraction on the CEA-CRG three-axis spectrometer IN22 at the Institut Laue Langevin.

  3. Thermodynamic modelling and in-situ neutron diffraction investigation of the (Ce + Mg + Zn) system

    International Nuclear Information System (INIS)

    Zhu, Zhijun; Gharghouri, Michael A.; Medraj, Mamoun; Lee, Soo Yeol; Pelton, Arthur D.

    2016-01-01

    Highlights: • All phase diagram and thermodynamic data critically assessed for the (Ce + Mg + Zn) system. • All phases described by optimized thermodynamic models. • In-situ neutron diffraction performed to identify phases and transition temperatures. • Assessments of other (RE + Mg + Zn) systems have been carried out simultaneously. • The final product is a thermodynamic database for multicomponent (Mg + RE + Zn) systems. - Abstract: All available phase diagram data for the (Ce + Mg + Zn) system were critically assessed. In-situ neutron diffraction (ND) experiments were performed on selected samples to identify phases and transition temperatures. A critical thermodynamic evaluation and optimization of the (Ce + Mg + Zn) system were carried out and model parameters for the thermodynamic properties of all phases were obtained. The phase transformation behaviour of selected samples was well resolved from the ND experiments and experimental data were used to refine the thermodynamic model parameters.

  4. Study and development of new dosemeters for thermal neutrons

    International Nuclear Information System (INIS)

    Urena N, F.

    1998-01-01

    An alanine-boron compound, alanine hydroborate, was synthesized and chemically characterized to be used for thermal neutrons fluence measurements. The synthesis of the compound was made by reacting the amino acid alanine with boric acid in three different media: acidic, neutral and alkaline. Physicochemical analysis showed that the alkaline medium is favorable for the synthesis of the alanine hydroborate. The compound was evaluated as a thermal neutron fluence detector by the detection of the free radical yield upon neutron thermal irradiation by Electron Paramagnetic Resonance (EPR). The present work also studies the EPR-signal response of the three preparations to thermal neutron irradiation (φ = 5 x 10 7 n/cm 2 -s). The following EPR signal parameters of the samples were investigated: peak-to-peak signal intensity vs. thermal neutron fluence Φ = φ Δt ; where Δt = 1, 5, 10, 20, 40, 60, 80, 90, 100, 110 and 120 h. , peak-to-peak signal intensity vs. microwave power, signal fading; repeatability, batch homogeneity, stability and zero dose response. It is concluded that these new products could be used in thermal neutron fluence estimations. (Author)

  5. Thermal neutron imaging in an active interrogation environment

    International Nuclear Information System (INIS)

    Vanier, P.E.; Forman, L.; Norman, D.R.

    2009-01-01

    We have developed a thermal-neutron coded-aperture imager that reveals the locations of hydrogenous materials from which thermal neutrons are being emitted. This imaging detector can be combined with an accelerator to form an active interrogation system in which fast neutrons are produced in a heavy metal target by means of excitation by high energy photons. The photo-induced neutrons can be either prompt or delayed, depending on whether neutronemitting fission products are generated. Provided that there are hydrogenous materials close to the target, some of the photo-induced neutrons slow down and emerge from the surface at thermal energies. These neutrons can be used to create images that show the location and shape of the thermalizing materials. Analysis of the temporal response of the neutron flux provides information about delayed neutrons from induced fission if there are fissionable materials in the target. The combination of imaging and time-of-flight discrimination helps to improve the signal-to-background ratio. It is also possible to interrogate the target with neutrons, for example using a D-T generator. In this case, an image can be obtained from hydrogenous material in a target without the presence of heavy metal. In addition, if fissionable material is present in the target, probing with fast neutrons can stimulate delayed neutrons from fission, and the imager can detect and locate the object of interest, using appropriate time gating. Operation of this sensitive detection equipment in the vicinity of an accelerator presents a number of challenges, because the accelerator emits electromagnetic interference as well as stray ionizing radiation, which can mask the signals of interest.

  6. Secondary extinction in cylindrical and spherical crystals for X-ray and neutron diffraction

    International Nuclear Information System (INIS)

    Hu Huachen; Li Zhaohuan; Yang Bin; Shen Caiwan

    2001-01-01

    The distribution of the reflection power ratio for a neutron or x-ray diffracted from a cylindrical crystal immersed in an homogenous incident beam is obtained by the numerical solution of the transfer equations for the first time. The profile well reflects all the physical properties of the absorption and extinction behaviour in the crystals. A systematic investigation of the secondary extinction for cylindrical and spherical crystals was carried out based on these results

  7. Stresses in plasma-sprayed Cr2O3 coatings measured by neutron diffraction

    Czech Academy of Sciences Publication Activity Database

    Dubský, Jiří; Prask, H. J.; Matějíček, Jiří; Gnäupel-Herold, T.

    2002-01-01

    Roč. 75, - (2002), s. 1-3 ISSN 0947-8396. [International Conference on Neutron Scattreing. Munich, 09.08.2001-13.08.2002] R&D Projects: GA ČR GA106/01/0094 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasma sprayed, diffraction Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 2.231, year: 2002

  8. Neutron diffraction studies on cobalt substituted BiFeO3

    Science.gov (United States)

    Ray, J.; Biswal, A. K.; Acharya, S.; Babu, P. D.; Siruguri, V.; Vishwakarma, P. N.

    2013-02-01

    A dilute concentration of single phase Cobalt substituted Bismuth ferrite, BiFe1-XCoXO3; (x=0, 0.02) is prepared by sol-gel auto combustion method. Room temperature neutron diffraction patterns show no change in the crystal and magnetic structure upon cobalt doping. The calculation of magnetic moments shows 3.848 μB for Fe+ and 2.85 μB for Co3+. The cobalt is found to be in intermediate spin state.

  9. The neutron diffraction of molten TlCl, TlBr, and TlI

    International Nuclear Information System (INIS)

    Satow, T.; Uemura, O.; Hoshino, K.; Watanabe, T.

    1984-01-01

    Structure factors S(K) for liquid TlCl, TlBr, and TlI are determined by neutron diffraction measurements. Atomic radial distribution functions (RDF) derived from S(K) are presented. All RDF values are slightly smaller than those of their solid state counter parts. Results show that TlX has a tendency not to retain cesium-chloride type local order, but to take sodium-chloride type order when melting

  10. Neutron diffraction study of the stress distribution in steel matrix around active NiTi inserts

    Czech Academy of Sciences Publication Activity Database

    Davydov, Vadim; Lukáš, Petr; Vrána, Miroslav; Malard, B.; Pilch, Jan; Maximov, V.; Šittner, Petr

    2010-01-01

    Roč. 527, č. 15 (2010), s. 3310-3316 ISSN 0921-5093 R&D Projects: GA ČR GAP107/10/0824; GA AV ČR(CZ) IAA200100627 Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z10100520 Keywords : In-situ neutron diffraction * Shape memory alloys * Residual stresses Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 2.090, year: 2010

  11. Neutron diffraction on CeMnAlD{sub x} (0{<=}x{<=}2.5)

    Energy Technology Data Exchange (ETDEWEB)

    Spatz, P.; Gross, K.; Schlapbach, L. [Fribourg Univ. (Switzerland); Fischer, P.; Fauth, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    CeMnAl was found to absorb considerable amounts of hydrogen. Part of the totally stored hydrogen is absorbed at low pressures (< 10 mbar). Additional hydrogen can be absorbed and desorbed reversible in a wide pressure range (10 mbar to 10 bar) at room temperature. In order to a better understanding of this new metal-hydride system, we performed neutron diffraction on deuterated CeMnAl samples with different D-concentrations. (author) 1 fig., 2 refs.

  12. Residual Stress Analysis for Engineering Applications by Means of Neutron Diffraction

    International Nuclear Information System (INIS)

    Gndupel-Herold, Thomas; Brand, Paul C.; Prask, Henry J.

    1999-01-01

    The economic and scientific importance of neutron diffraction residual stress analysis has led to an increasing number of suitable instruments worldwide. Recently, a dedicated state-of-the-art diffractometer has been installed at the National Institute of Standards and Technology reactor. It has been used for a variety of measurements on basic and engineering stress problems. Among the most prominent examples that have been investigated are residual stresses in rails, weldments, and plasma-sprayed coatings

  13. Neutron powder diffraction studies of Hydrogen and Denterium in Palladium Phosphides

    International Nuclear Information System (INIS)

    Andersson, Y.

    1986-01-01

    The use of the Rietveld-type profile refinements on neutron powder diffraction intensity data for determining crystallographic positions of hydrogen and deuterium in metal hydrides is illustrated by results obtained on some hydrogenated and deuterated palladium phosphides. The structural features of the solid solutions of hydrogen and deuterium in Pd/sb15/P/sb2/ Pd/sb6/P and Pd/sb3/P/sb1-u/ (0< u<0.28) are briefly presented and discussed

  14. Complex investigation of deformation twinning in gamma-TiAl by TEM and neutron diffraction

    Czech Academy of Sciences Publication Activity Database

    Beran, Přemysl; Heczko, Milan; Kruml, Tomáš; Panzner, T.; van Petegem, S.

    2016-01-01

    Roč. 95, OCT (2016), s. 647-662 ISSN 0022-5096 R&D Projects: GA ČR(CZ) GAP107/11/0704; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 ; RVO:61389005 Keywords : dislocations * twinning * polycrystalline material * neutron diffraction * electron microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism; JL - Materials Fatigue, Friction Mechanics (UFM-A) Impact factor: 4.255, year: 2016

  15. Design of a new lithium ion battery test cell for in-situ neutron diffraction measurements

    Czech Academy of Sciences Publication Activity Database

    Roberts, M.; Biendicho, J. J.; Hull, S.; Beran, Přemysl; Gustafsson, T.; Svensson, G.; Edstrom, K.

    2013-01-01

    Roč. 226, MAR 15 (2013), s. 249-255 ISSN 0378-7753 R&D Projects: GA MŠk(XE) LM2011019 Institutional support: RVO:61389005 Keywords : neutron * Lithium * LiFePO4 * diffraction * in situ Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.211, year: 2013 http://www.sciencedirect.com/science/article/pii/S0378775312016515

  16. Development of a sample environment for neutron diffraction at low temperature

    International Nuclear Information System (INIS)

    Lee, Jeong Soo; Lee, Chang Hee; Choi, Yong Nam

    2000-06-01

    This report contains the development of low temperature sample environment for the neutron diffraction and its utilization techniques. With this research, a low temperature experimental facility of T=10-300 K was developed. We measured magnetic peak of La 1 .4Sr 1 .6Mn 2 O 7 due to low temperature phase transition successfully by this unit installed at the sample table of HRPD. Therefore, the research capability for various materials under the low temperature was expanded

  17. Crystal structure of barium hydride, determined by neutron diffraction experiments on BaD2

    International Nuclear Information System (INIS)

    Bronger, W.; Scha Chi-Chien; Mueller, P.

    1987-01-01

    A reinvestigation of the structure of BaH 2 and BaD 2 was performed on powdered samples by X-ray- and neutron diffraction experiments. It is shown, that the hydrogen positions correspond with those found in calcium deuteride and not with those proposed in the literature. The classification of barium hydride in the PbCl 2 structure type is discussed. (author)

  18. Deformation behavior of Mg-alloy-based composites at different temperatures studied by neutron diffraction

    Czech Academy of Sciences Publication Activity Database

    Farkas, Gergely; Máthis, K.; Pilch, Jan; Minárik, P.; Lukáš, Petr; Vinogradov, A.

    2017-01-01

    Roč. 685, FEB (2017), s. 284-293 ISSN 0921-5093 R&D Projects: GA ČR GB14-36566G; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : magnesium alloy matrix composite s * neutron diffraction * deformation * twinning Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.094, year: 2016

  19. A high-resolution neutron powder diffraction study of neodymium doping in barium cerate

    DEFF Research Database (Denmark)

    Knight, K.S.; Bonanos, N.

    1995-01-01

    High-resolution neutron powder diffraction data have been collected on 6 perovskites of composition BaCe1-xNdxO3-x/(2), with 0 less than or equal to x less than or equal to 0.2, in which structural phase transitions Pmcn-->P4/mbm at x=0.05, and P4/mbm-->Pm3m at x=0.1, were inferred from a recent ...

  20. Structural characterisation of 1- and 2-dimensional transition metal polymers using powder neutron diffraction

    International Nuclear Information System (INIS)

    James, M.

    1999-01-01

    Powder neutron diffraction provides an alternate technique for the structural study of transition metal polymers and finds utility over standard X-ray methods in two significant ways. Firstly, due to a different instrument geometry, preferred orientation effects are removed from the system. The second advantage gained by utilising neutrons is that H atoms in the sample contribute much more to the nuclear scattering of the diffraction profile - allowing their atomic position to be accurately determined. In X-ray diffraction studies, where H atoms typically account for only ∼3-5% of the scattering from the sample, it is essentially impossible to refine their position in the molecular structure. The structures of several transition metal polymers have been determined using neutrons from the HIFAR reactor at ANSTO and the Powder Diffractometers HRPD and MRPD, along with Rietveld refinement methods. The 1-dimensional polymer dibromobis(thiazole)nickel(II) illustrated in the paper is characteristic of these types of systems which are comprised of transition metal centres bridged by halogen atoms with pendant amine side groups

  1. In situ high-pressure measurement of crystal solubility by using neutron diffraction

    Science.gov (United States)

    Chen, Ji; Hu, Qiwei; Fang, Leiming; He, Duanwei; Chen, Xiping; Xie, Lei; Chen, Bo; Li, Xin; Ni, Xiaolin; Fan, Cong; Liang, Akun

    2018-05-01

    Crystal solubility is one of the most important thermo-physical properties and plays a key role in industrial applications, fundamental science, and geoscientific research. However, high-pressure in situ measurements of crystal solubility remain very challenging. Here, we present a method involving high-pressure neutron diffraction for making high-precision in situ measurements of crystal solubility as a function of pressure over a wide range of pressures. For these experiments, we designed a piston-cylinder cell with a large chamber volume for high-pressure neutron diffraction. The solution pressures are continuously monitored in situ based on the equation of state of the sample crystal. The solubility at a high pressure can be obtained by applying a Rietveld quantitative multiphase analysis. To evaluate the proposed method, we measured the high-pressure solubility of NaCl in water up to 610 MPa. At a low pressure, the results are consistent with the previous results measured ex situ. At a higher pressure, more reliable data could be provided by using an in situ high-pressure neutron diffraction method.

  2. Manufacturing of thermal neutron sensor using pMOS

    International Nuclear Information System (INIS)

    Lee, Nam Ho; Kim, Seung Ho

    2005-05-01

    A pMOSFET sensor having a Gadolinium converter has been invented successfully as a slow neutron sensor that is sensitive to neutron energy down to 0.025 eV. The Gd layer converts low energy neutrons to ionizing radiation of which the amount is proportional to neutron dose. Ionising radiation from neutron reactions changes the charge state of the gate oxide of the pMOSFET. The Gd-pMOSFETs were tested at a neutron beam port of HANARO research reactor and a 60 CO irradiation facility to investigate slow neutron response and gamma response, respectively. The voltage change was proportional to the accumulated slow neutron dose. The results from Gd coupled MOSFET neutron dosemeters shows an excellent sensitivity (15 - 16mV/cGy) and linearity to thermal neutrons with negligible background contamination. The results demonstrate the outstanding performance of the Gd coupled MOSFET neutron dosemeters clearly. The Gd-pMOSFET can also be used in a mixed radiation field by subtracting the voltage change of a pMOSFET without Gd from that of the Gd-pMOSFET

  3. Study of a nTHGEM-based thermal neutron detector

    Science.gov (United States)

    Li, Ke; Zhou, Jian-Rong; Wang, Xiao-Dong; Xiong, Tao; Zhang, Ying; Xie, Yu-Guang; Zhou, Liang; Xu, Hong; Yang, Gui-An; Wang, Yan-Feng; Wang, Yan; Wu, Jin-Jie; Sun, Zhi-Jia; Hu, Bi-Tao

    2016-07-01

    With new generation neutron sources, traditional neutron detectors cannot satisfy the demands of the applications, especially under high flux. Furthermore, facing the global crisis in 3He gas supply, research on new types of neutron detector as an alternative to 3He is a research hotspot in the field of particle detection. GEM (Gaseous Electron Multiplier) neutron detectors have high counting rate, good spatial and time resolution, and could be one future direction of the development of neutron detectors. In this paper, the physical process of neutron detection is simulated with Geant4 code, studying the relations between thermal conversion efficiency, boron thickness and number of boron layers. Due to the special characteristics of neutron detection, we have developed a novel type of special ceramic nTHGEM (neutron THick GEM) for neutron detection. The performance of the nTHGEM working in different Ar/CO2 mixtures is presented, including measurements of the gain and the count rate plateau using a copper target X-ray source. A detector with a single nTHGEM has been tested for 2-D imaging using a 252Cf neutron source. The key parameters of the performance of the nTHGEM detector have been obtained, providing necessary experimental data as a reference for further research on this detector. Supported by National Natural Science Foundation of China (11127508, 11175199, 11205253, 11405191), Key Laboratory of Neutron Physics, CAEP (2013DB06, 2013BB04) and CAS (YZ201512)

  4. Investigation of TbMn2O5 by polarized neutron diffraction.

    Science.gov (United States)

    Zobkalo, I A; Gavrilov, S V; Sazonov, A; Hutanu, V

    2018-05-23

    In order to make a new approach to the elucidation of the microscopic mechanisms of multiferroicity in the RMn 2 O 5 family, experiments with different methods of polarized neutrons scattering were performed on a TbMn 2 O 5 single crystal. We employed three different techniques of polarized neutron diffraction without the analysis after scattering, the XYZ-polarization analysis, and technique of spherical neutron polarimetry (SNP). Measurements with SNP were undertaken both with and without external electric field. A characteristic difference in the population of 'right' and 'left' helix domains in all magnetically ordered phases of TbMn 2 O 5 , was observed. This difference can be controlled by an external electric field in the field-cooled mode. The analysis of the results gives an evidence that antisymmetric Dzyaloshinsky-Moria exchange is effective in all the magnetic phases in TbMn 2 O 5 .

  5. Polarized neutron diffraction - a tool for testing extinction models: application to yttrium iron garnet

    International Nuclear Information System (INIS)

    Bonnet, M.; Delapalme, A.; Becker, P.

    1976-01-01

    This paper shows that polarized neutron experiments, which do not depend on any scale factor, are very dependent on extinction and provide original tests for extinction models. Moon, Koehler, Cable and Child (1972) have formulated the problem and proposed a first-order solution applicable only when the extinction is small. In the first part, some analytical derivations of secondary extinction corrections are discussed, using the formalism of Becker and Coppens (1974). In the second part, the main principles governing polarized neutron diffraction are briefly reviewed, with a special discussion of extinction problems. The method is then applied to the case of yttrium iron garnet (YIG). This experiment shows the technique of polarized neutrons to be very powerful for testing extinction models and for deciding whether the crystal behaves dynamically or kinematically (following Kato's criterion). (Auth.)

  6. Investigation of TbMn2O5 by polarized neutron diffraction

    Science.gov (United States)

    Zobkalo, I. A.; Gavrilov, S. V.; Sazonov, A.; Hutanu, V.

    2018-05-01

    In order to make a new approach to the elucidation of the microscopic mechanisms of multiferroicity in the RMn2O5 family, experiments with different methods of polarized neutrons scattering were performed on a TbMn2O5 single crystal. We employed three different techniques of polarized neutron diffraction without the analysis after scattering, the XYZ-polarization analysis, and technique of spherical neutron polarimetry (SNP). Measurements with SNP were undertaken both with and without external electric field. A characteristic difference in the population of ‘right’ and ‘left’ helix domains in all magnetically ordered phases of TbMn2O5, was observed. This difference can be controlled by an external electric field in the field-cooled mode. The analysis of the results gives an evidence that antisymmetric Dzyaloshinsky-Moria exchange is effective in all the magnetic phases in TbMn2O5.

  7. 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

  8. Neutron powder diffraction at a pulsed neutron source: a study of resolution effects

    International Nuclear Information System (INIS)

    Faber, J. Jr.; Hitterman, R.L.

    1985-11-01

    The General Purpose Powder Diffractometer (GPPD), a high resolution (Δd/d = 0.002) time-of-flight instrument, exhibits a resolution function that is almost independent of d-spacing. Some of the special properties of time-of-flight scattering data obtained at a pulsed neutron source will be discussed. A method is described that transforms wavelength dependent data, obtained at a pulsed neutron source, so that standard structural least-squares analyses can be applied. Several criteria are given to show when these techniques are useful in time-of-flight data analysis. 14 refs., 6 figs., 1 tab

  9. Thermal neutron flux measurements using neutron-electron converters; Mesure de flux de neutrons thermiques avec des convertisseurs neutrons electrons

    Energy Technology Data Exchange (ETDEWEB)

    Le Meur, R; Lecomte, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    The operation of neutron-electron converters designed for measuring thermal neutron fluxes is examined. The principle is to produce short lived isotopes emitting beta particles, by activation, and to measure their activity not by extracting them from the reactor, but directly in the reactor using the emitted electrons to deflect the needle of a galvanometer placed outside the flux. After a theoretical study, the results of the measurements are presented; particular attention is paid to a new type of converter characterized by a layer structure. The converters are very useful for obtaining flux distributions with more than 10{sup 7} neutrons cm{sup -2}*sec{sup -1}. They work satisfactorily in pressurized carbon dioxide at 400 Celsius degrees. Some points still have to be cleared up however concerning interfering currents in the detectors and the behaviour of the dielectrics under irradiation. (authors) [French] On examine le fonctionnement de convertisseurs neutrons electrons destines a des mesures de flux de neutrons thermiques. Le principe est de former par activation des isotopes a periodes courtes et a emission beta et de mesurer leur activite non pas en les sortant du reacteur, mais directement en pile, utilisant les electrons emis pour faire devier l'aiguille d'un galvanometre place hors flux. Apres une etude theorique, on indique des resultats de mesures obtenus, en insistant particulierement sur un nouveau type de convertisseur, caracterise par sa structure stratifiee. Les convertisseurs sont tres interessants pour tracer, des cartes de flux a partir de 10{sup 7} neutrons cm{sup -2}*s{sup -1}. Ils sont utilisables pour des flux de 10{sup 14} neutrons cm{sup -2}*s{sup -1}. Ils fonctionnent correctement dans du gaz carbonique sous pression a 400 C. Des points restent cependant a eclaircir concernant les courants parasites dans les detecteurs et le comportement des dielectriques pendant leur irradiation. (auteur)

  10. Experimental characterization of semiconductor-based thermal neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); Bortot, D.; Pola, A.; Introini, M.V.; Lorenzoli, M. [Politecnico di Milano, Dipartimento di Energia, via La Masa 34, 20156 Milano (Italy); INFN—Milano, Via Celoria 16, 20133 Milano (Italy); Gómez-Ros, J.M. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); CIEMAT, Av. Complutense 40, 28040 Madrid (Spain); Sacco, D. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); INAIL—DIT, Via di Fontana Candida 1, 00040 Monteporzio Catone (Italy); Esposito, A.; Gentile, A.; Buonomo, B. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); Palomba, M.; Grossi, A. [ENEA Triga RC-1C.R. Casaccia, via Anguillarese 301, 00060 S. Maria di Galeria, Roma (Italy)

    2015-04-21

    In the framework of NESCOFI@BTF and NEURAPID projects, active thermal neutron detectors were manufactured by depositing appropriate thickness of {sup 6}LiF on commercially available windowless p–i–n diodes. Detectors with different radiator thickness, ranging from 5 to 62 μm, were manufactured by evaporation-based deposition technique and exposed to known values of thermal neutron fluence in two thermal neutron facilities exhibiting different irradiation geometries. The following properties of the detector response were investigated and presented in this work: thickness dependence, impact of parasitic effects (photons and epithermal neutrons), linearity, isotropy, and radiation damage following exposure to large fluence (in the order of 10{sup 12} cm{sup −2})

  11. Sample positioning in neutron diffraction experiments using a multi-material fiducial marker

    Energy Technology Data Exchange (ETDEWEB)

    Marais, D., E-mail: Deon.Marais@necsa.co.za [Research and Development Division, South African Nuclear Energy Corporation (Necsa) SOC Limited, PO Box 582, Pretoria 0001 (South Africa); School of Mechanical and Nuclear Engineering, North-West University, Potchefstroom 2520 (South Africa); Venter, A.M., E-mail: Andrew.Venter@necsa.co.za [Research and Development Division, South African Nuclear Energy Corporation (Necsa) SOC Limited, PO Box 582, Pretoria 0001 (South Africa); Faculty of Agriculture Science and Technology, North-West University, Mahikeng 2790 (South Africa); Markgraaff, J., E-mail: Johan.Markgraaff@nwu.ac.za [School of Mechanical and Nuclear Engineering, North-West University, Potchefstroom 2520 (South Africa); James, J., E-mail: Jon.James@open.ac.uk [Faculty of Mathematics, Computing and Technology, The Open University, Milton Keynes, MK76AA England (United Kingdom)

    2017-01-01

    An alternative sample positioning method is reported for use in conjunction with sample positioning and experiment planning software systems deployed on some neutron diffraction strain scanners. In this approach, the spherical fiducial markers and location trackers used with optical metrology hardware are replaced with a specifically designed multi-material fiducial marker that requires one diffraction measurement. In a blind setting, the marker position can be determined within an accuracy of ±164 µm with respect to the instrument gauge volume. The scheme is based on a pre-determined relationship that links the diffracted peak intensity to the absolute positioning of the fiducial marker with respect to the instrument gauge volume. Two methods for establishing the linking relationship are presented, respectively based on fitting multi-dimensional quadratic functions and a cross-correlation artificial neural network.

  12. Neutron diffraction studies of water in meso- and micro-pores

    International Nuclear Information System (INIS)

    Steytler, D.C.; Dore, J.C.; Wright, C.J.

    1982-07-01

    Neutron diffraction studies have been made for D 2 O water in two high surface-area silica samples, Spherisorb and Gasil. The results show that the structural arrangement is similar to that of bulk water and that the modification due to the interface is restricted to a range of the order of 10 A or less. Measurements also indicate that the dispersed water undergoes significant structural changes with temperature variation but the behaviour is similar to that of the bulk liquid. The differences observed in the diffraction patterns can be partially described in terms of diffraction broadening due to the small volume of the dispersed water but there remains a significant variation which appears to be related to the hydrogen-bonding interactions. (author)

  13. Study of the α and β phases of quartz by neutron multiple diffraction

    International Nuclear Information System (INIS)

    Mazzocchi, V.L.

    1984-01-01

    Crystal structures of α and β phases of quartz are studied, employing neutron multiple diffraction as a method of analysis. Theoretical multiple diffraction patterns in a many-beam case were determined by a computer program which calculates intensities of beams as sums of Taylor's series expansions, retaining terms up to a order n. Experimental 'umweg' and transmitted beam patterns were obtained for the 00.1 primary reflection of α and β phases of quartz. To calculate α - quartz multiple diffraction intensities it was necessary to determine the Dauphine twinning fraction for the crystal after having passed by the β-phase. For the two models of β-quartz a better agreement between experimental and calculated integrated intensities was found for the disordered structure model based on split-half-oxigen positions. (Author) [pt

  14. Accounting for the thermal neutron flux depression in voluminous samples for instrumental neutron activation analysis

    International Nuclear Information System (INIS)

    Overwater, R.M.W.; Hoogenboom, J.E.

    1994-01-01

    At the Delft University of Technology Interfaculty Reactor Institute, a facility has been installed to irradiate cylindrical samples with diameters up to 15 cm and weights up to 50 kg for instrumental neutron activation analysis (INAA) purposes. To be able to do quantitative INAA on voluminous samples, it is necessary to correct for gamma-ray absorption, gamma-ray scattering, neutron absorption, and neutron scattering in the sample. The neutron absorption and the neutron scattering are discussed. An analytical solution is obtained for the diffusion equation in the geometry of the irradiation facility. For samples with known composition, the neutron flux--as a function of position in the sample--can be calculated directly. Those of unknown composition require additional flux measurements on which least-squares fitting must be done to obtain both the thermal neutron diffusion coefficient D s and the diffusion length L s of the sample. Experiments are performed to test the theory

  15. 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.)

  16. Transmutation of Minor Actinide in well thermalized neutron field and application of advanced neutron source (ANS)

    International Nuclear Information System (INIS)

    Iwasaki, Tomohiko; Hirakawa, Naohiro

    1995-01-01

    Transmutation of Minor Actinide (MA) in a well thermalized neutron field was studied. Since MA nuclides have large effective cross sections in the well thermalized neutron field, the transmutation in the well thermalized neutron field has an advantage of high transmutation rate. However, the transmutation rate largely decreases by accumulation of 246 Cm when MA is transmuted only in the well thermalized neutron field for a long period. An acceleration method of burn-up of 246 Cm was studied. High transmutation rate can be obtained by providing a neutron field with high flux in the energy region between 1 and 100 eV. Two stage transmutation using the well thermalized neutron field and this field can transmute MA rapidly. The applicability of the Advanced Neutron Source (ANS) to the transmutation of MA was examined for a typical MA with the composition in the high-level waste generated in the conventional PWR. If the ANS is applied without changing the fuel inventory, the amount of MA which corresponds to that produced by a conventional 1,175 MWe PWR in one year can be transmuted by the ANS in one year. Furthermore, the amount of the residual can be reduced to about 1g (10 -5 of the initial MA weight) by continuing the transmutation for 5 years owing to the two stage transmutation. (author)

  17. Response of six neutron survey meters in mixed fields of fast and thermal neutrons.

    Science.gov (United States)

    Kim, S I; Kim, B H; Chang, I; Lee, J I; Kim, J L; Pradhan, A S

    2013-10-01

    Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the (241)Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ∼9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ∼85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ∼50 % in the thermal neutron field.

  18. Neutron- and X-ray diffraction investigations for the metallic glasses Ni81B19 and Co80P20

    International Nuclear Information System (INIS)

    Sperl, W.

    1982-01-01

    By means of isotope substitution for three chemically and technically identical amorphous Ni 81 B 19 samples neutron diffraction experiments are performed and the partial structure factors and the partial pair correlation functions are determined. (BHO)

  19. Feasibility study on using imaging plates to estimate thermal neutron fluence in neutron-gamma mixed fields

    International Nuclear Information System (INIS)

    Fujibuchi, T.; Tanabe, Y.; Sakae, T.; Terunuma, T.; Isobe, T.; Kawamura, H.; Yasuoka, K.; Matsumoto, T.; Harano, H.; Nishiyama, J.; Masuda, A.; Nohtomi, A.

    2011-01-01

    In current radiotherapy, neutrons are produced in a photonuclear reaction when incident photon energy is higher than the threshold. In the present study, a method of discriminating the neutron component was investigated using an imaging plate (IP) in the neutron-gamma-ray mixed field. Two types of IP were used: a conventional IP for beta- and gamma rays, and an IP doped with Gd for detecting neutrons. IPs were irradiated in the mixed field, and the photo-stimulated luminescence (PSL) intensity of the thermal neutron component was discriminated using an expression proposed herein. The PSL intensity of the thermal neutron component was proportional to thermal neutron fluence. When additional irradiation of photons was added to constant neutron irradiation, the PSL intensity of the thermal neutron component was not affected. The uncertainty of PSL intensities was approximately 11.4 %. This method provides a simple and effective means of discriminating the neutron component in a mixed field. (authors)

  20. EL-2 reactor: Thermal neutron flux distribution; EL-2: Repartition du flux de neutrons thermiques

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, A; Genthon, J P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    The flux distribution of thermal neutrons in EL-2 reactor is studied. The reactor core and lattices are described as well as the experimental reactor facilities, in particular, the experimental channels and special facilities. The measurement shows that the thermal neutron flux increases in the central channel when enriched uranium is used in place of natural uranium. However the thermal neutron flux is not perturbed in the other reactor channels by the fuel modification. The macroscopic flux distribution is measured according the radial positioning of fuel rods. The longitudinal neutron flux distribution in a fuel rod is also measured and shows no difference between enriched and natural uranium fuel rods. In addition, measurements of the flux distribution have been effectuated for rods containing other material as steel or aluminium. The neutron flux distribution is also studied in all the experimental channels as well as in the thermal column. The determination of the distribution of the thermal neutron flux in all experimental facilities, the thermal column and the fuel channels has been made with a heavy water level of 1825 mm and is given for an operating power of 1000 kW. (M.P.)

  1. Investigation of the neutron diffraction anomaly and electrical behaviour of α-LiIO3 single crystal under AC field

    International Nuclear Information System (INIS)

    Wang Guang; Yang Zhen

    1990-01-01

    A systematic study of the unique neutron diffraction and electric behaviour of α-LiIO 3 single crystal under AC field is reported. A frequency dependent rectification effect was observed and can be explained as the relaxation process in the ionic conduction. Theoretical treatment using Boltzmann equation gives satisfactory agreement with experimental results. The neutron diffraction anomaly can be attributed to the effect of the rectified DC current in the sample

  2. Neutron Thermalization and Reactor Spectra. Vol. II. Proceedings of the Symposium on Neutron Thermalization and Reactor Spectra

    International Nuclear Information System (INIS)

    1968-01-01

    Proceedings of a Symposium organized by the IAEA and held at Ann Arbor, Michigan, USA, 17 - 21 July 1967. The meeting was attended by 143 participants from 24 Member States and one international organization. Contents: (Vol.I) Theory of neutron thermalization (15 papers); Scattering law (20 papers); Angular, space, temperature and time dependence of neutron spectra (9 papers). (Vol.II) Measurement of thermal neutron spectra and spectral indices, and comparison with theory (17 papers); Time-dependent problems in neutron thermalization (12 papers). Each paper is in its original language (61 English, 1 French and 11 Russian) and is preceded by an abstract in English with one in the original language if this is not English. Discussions are in English.

  3. On the use of silicon as thermal neutron filter

    International Nuclear Information System (INIS)

    Adib, M.; Habib, N.; Ashry, A.; Fathalla, M.

    2003-01-01

    A simple formula is given which allows to calculate the contribution of the total neutron cross-section including the Bragg scattering from different (hkl) planes to the neutron transmission through a solid crystalline silicon. The formula takes into account the silicon form of poly or mono crystals and its parameters. A computer program DSIC was developed to provide the required calculations. The calculated values of the total neutron cross-section of perfect silicon crystal at room and liquid nitrogen temperatures were compared with the experimental ones. The obtained agreement shows that the simple formula fits the experimental data with sufficient accuracy. A good agreement was also obtained between the calculated and measured values of polycrystalline silicon in the energy range from 5 eV to 500 μeV. The feasibility study on using a poly-crystalline silicon as a cold neutron filter and mono-crystalline as a thermal neutron one is given. The optimum crystal thickness, mosaic spread, temperature and cutting plane for efficiently transmitting the thermal reactor neutrons, while rejecting both fast neutrons and gamma rays accompanying the thermal ones for the mono crystalline silicon are also given

  4. On the use of silicon as thermal neutron filter

    Energy Technology Data Exchange (ETDEWEB)

    Adib, M.; Habib, N.; Ashry, A.; Fathalla, M. E-mail: mohamedfathalla@hotmail.com

    2003-12-01

    A simple formula is given which allows to calculate the contribution of the total neutron cross-section including the Bragg scattering from different (hkl) planes to the neutron transmission through a solid crystalline silicon. The formula takes into account the silicon form of poly or mono crystals and its parameters. A computer program DSIC was developed to provide the required calculations. The calculated values of the total neutron cross-section of perfect silicon crystal at room and liquid nitrogen temperatures were compared with the experimental ones. The obtained agreement shows that the simple formula fits the experimental data with sufficient accuracy. A good agreement was also obtained between the calculated and measured values of polycrystalline silicon in the energy range from 5 eV to 500 {mu}eV. The feasibility study on using a poly-crystalline silicon as a cold neutron filter and mono-crystalline as a thermal neutron one is given. The optimum crystal thickness, mosaic spread, temperature and cutting plane for efficiently transmitting the thermal reactor neutrons, while rejecting both fast neutrons and gamma rays accompanying the thermal ones for the mono crystalline silicon are also given.

  5. Chemical warfare agents identification by thermal neutron detection

    International Nuclear Information System (INIS)

    Liu Boxue; Ai Xianyun; Tan Daoyuan; Zhang Dianqin

    2000-01-01

    The hydrogen concentration determination by thermal neutron detection is a non-destructive, fast and effective method to identify chemical warfare agents and TNT that contain different hydrogen fraction. When an isotropic neutron source is used to irradiate chemical ammunition, hydrogen atoms of the agent inside shell act as a moderator and slow down neutrons. The number of induced thermal neutrons depends mainly upon hydrogen content of the agent. Therefore measurement of thermal neutron influence can be used to determine hydrogen atom concentration, thereby to determine the chemical warfare agents. Under a certain geometry three calibration curves of count rate against hydrogen concentration were measured. According to the calibration curves, response of a chemical agent or TNT could be calculated. Differences of count rate among chemical agents and TNT for each kind of shells is greater than five times of standard deviations of count rate for any agent, so chemical agents or TNT could be identified correctly. Meanwhile, blast tube or liquid level of chemical warfare agent could affect the response of thermal neutron count rate, and thereby the result of identification. (author)

  6. Impact of neutron irradiation on thermal helium desorption from iron

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xunxiang, E-mail: hux1@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Field, Kevin G. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Taller, Stephen [University of Michigan, Ann Arbor, MI 48109 (United States); Katoh, Yutai [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Wirth, Brian D. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); University of Tennessee, Knoxville, TN 37996 (United States)

    2017-06-15

    The synergistic effect of neutron irradiation and transmutant helium production is an important concern for the application of iron-based alloys as structural materials in fission and fusion reactors. In this study, we investigated the impact of neutron irradiation on thermal helium desorption behavior in high purity iron. Single crystalline and polycrystalline iron samples were neutron irradiated in HFIR to 5 dpa at 300 °C and in BOR-60 to 16.6 dpa at 386 °C, respectively. Following neutron irradiation, 10 keV He ion implantation was performed at room temperature on both samples to a fluence of 7 × 10{sup 18} He/m{sup 2}. Thermal desorption spectrometry (TDS) was conducted to assess the helium diffusion and clustering kinetics by analyzing the desorption spectra. The comparison of He desorption spectra between unirradiated and neutron irradiated samples showed that the major He desorption peaks shift to higher temperatures for the neutron-irradiated iron samples, implying that strong trapping sites for He were produced during neutron irradiation, which appeared to be nm-sized cavities through TEM examination. The underlying mechanisms controlling the helium trapping and desorption behavior were deduced by assessing changes in the microstructure, as characterized by TEM, of the neutron irradiated samples before and after TDS measurements.

  7. Residual Stress Measurement of Coarse Crystal Grain in Aluminium Casting Alloy by Neutron Diffraction

    International Nuclear Information System (INIS)

    Nishida, Masayuki; Watanabe, Yoshitaka; Hanabusa, Takao

    2009-01-01

    Full text: Neutron stress measurement can detect strain and stress information in deep region because of large penetration ability of neutron beams. The present paper describes procedure and results in the residual stress measurement of aluminium casting alloy by neutron diffraction. Usually, the aluminium casting alloy includes the large crystal grains. The existence of large crystal grains makes it difficult to estimate the residual stresses in highly accuracy. In this study, the modified three axial method using Hook's equation was employed for neutron stress measurement. These stress measurements were performed under the two kinds of new techniques. One is a rocking curve method to calculate the principal strains in three directions. The peak profiles which appear discretely on rocking curves were translated to principle stresses by the Bragg law and the basic elastic theory. Another is the consideration of measurement positions and the edge effect in the neutron irradiated area (volume gage). The edge effect generates the errors of 2θ-peak position in the neutron stress measurement. In this study, the edge effect was investigated in detail by a small bit of copper single crystal. The copper bit was moved and scanned on three dimensionally within the gage volume. Furthermore, the average strains of symmetrical positions are measure by the sample turning at 180 degrees, because the error distributions of the 2θ-peak position followed to positions inside the gage volume. Form these results of this study, the residual stresses in aluminium casting alloy which includes the large crystal grains were possible to estimate by neutron stress measurement with the rocking curve method and the correction of the edge effect. (author)

  8. In Situ Neutron Diffraction of Rare-Earth Phosphate Proton Conductors Sr/Ca-doped LaPO4 at Elevated Temperatures

    Science.gov (United States)

    Al-Wahish, Amal; Al-Binni, Usama; Bridges, C. A.; Huq, A.; Bi, Z.; Paranthaman, M. P.; Tang, S.; Kaiser, H.; Mandrus, D.

    Acceptor-doped lanthanum orthophosphates are potential candidate electrolytes for proton ceramic fuel cells. We combined neutron powder diffraction (NPD) at elevated temperatures up to 800° C , X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) to investigate the crystal structure, defect structure, thermal stability and surface topography. NPD shows an average bond length distortion in the hydrated samples. We employed Quasi-Elastic Neutron Scattering (QENS) and electrochemical impedance spectroscopy (EIS) to study the proton dynamics of the rare-earth phosphate proton conductors 4.2% Sr/Ca-doped LaPO4. We determined the bulk diffusion and the self-diffusion coefficients. Our results show that QENS and EIS are probing fundamentally different proton diffusion processes. Supported by the U.S. Department of Energy.

  9. Focusing mirrors for enhanced neutron radiography with thermal neutrons and application for irradiated nuclear fuel

    Science.gov (United States)

    Rai, Durgesh K.; Abir, Muhammad; Wu, Huarui; Khaykovich, Boris; Moncton, David E.

    2018-01-01

    Neutron radiography is a powerful method of probing the structure of materials based on attenuation of neutrons. This method is most suitable for materials containing heavy metals, which are not transparent to X-rays, for example irradiated nuclear fuel and other nuclear materials. Neutron radiography is one of the first non-distractive post-irradiated examination methods, which is applied to gain an overview of the integrity of irradiated nuclear fuel and other nuclear materials. However, very powerful gamma radiation emitted by the samples is damaging to the electronics of digital imaging detectors and has so far precluded the use of modern detectors. Here we describe a design of a neutron microscope based on focusing mirrors suitable for thermal neutrons. As in optical microscopes, the sample is separated from the detector, decreasing the effect of gamma radiation. In addition, the application of mirrors would result in a thirty-fold gain in flux and a resolution of better than 40 μm for a field-of-view of about 2.5 cm. Such a thermal neutron microscope can be useful for other applications of neutron radiography, where thermal neutrons are advantageous.

  10. A design study on hyper-thermal neutron irradiation field for neutron capture therapy at Kyoto University Reactor

    International Nuclear Information System (INIS)

    Sakurai, Y.; Kobayashi, T.

    2000-01-01

    A study about the installation of a hyper-thermal neutron converter to a clinical collimator was performed, as a series of the design study on a hyper-thermal neutron irradiation field at the Heavy Water Neutron Irradiation Facility of Kyoto University Reactor. From the parametric-surveys by Monte Carlo calculation, it was confirmed that the practical irradiation field of hyper-thermal neutrons would be feasible by the modifications of the clinical collimator and the bismuth-layer structure. (author)

  11. Thermal compression modulus of polarized neutron matter

    International Nuclear Information System (INIS)

    Abd-Alla, M.

    1990-05-01

    We applied the equation of state for pure polarized neutron matter at finite temperature, calculated previously, to calculate the compression modulus. The compression modulus of pure neutron matter at zero temperature is very large and reflects the stiffness of the equation of state. It has a little temperature dependence. Introducing the spin excess parameter in the equation of state calculations is important because it has a significant effect on the compression modulus. (author). 25 refs, 2 tabs

  12. Boron neutron capture therapy (BNCT). Recent aspect, a change from thermal neutron to epithermal neutron beam and a new protocol

    International Nuclear Information System (INIS)

    Nakagawa, Yoshinobu

    1999-01-01

    Since 1968, One-hundred seventy three patients with glioblastoma (n=81), anaplastic astrocytoma (n=44), low grade astrocytoma (n=16) or other types of tumor (n=32) were treated by boron-neutron capture therapy (BNCT) using a combination of thermal neutron and BSH in 5 reactors (HTR n=13, JRR-3 n=1, MuITR n=98, KUR n=28, JRR-2 n=33). Out of 101 patients with glioma treated by BNCT under the recent protocol, 33 (10 glioblastoma, 14 anaplastic astrocytoma, 9 low grade astrocytoma) patients lived or have lived longer than 3 years. Nine of these 33 lived or have lived longer than 10 years. According to the retrospective analysis, the important factors related to the clinical results were tumor dose radiation dose and maximum radiation dose in thermal brain cortex. The result was not satisfied as it was expected. Then, we decided to introduce mixed beams which contain thermal neutron and epithermal neutron beams. KUR was reconstructed in 1996 and developed to be available to use mixed beams. Following the shutdown of the JRR-2, JRR-4 was renewed for medical use in 1998. Both reactors have capacity to yield thermal neutron beam, epithermal neutron beam and mixed beams. The development of the neutron source lead us to make a new protocol. (author)

  13. Methane storage mechanism in the metal-organic framework Cu3(btc)2: An in situ neutron diffraction study

    NARCIS (Netherlands)

    Getzschmann, J.; Senkovska, I.; Wallacher, D.; Tovar, M.; Fairen-Jimenez, D.; Düren, T.; van Baten, J.M.; Krishna, R.; Kaskel, S.

    2010-01-01

    The adsorption of deutero-methane (CD4) in Cu3(btc)2 (HKUST-1) was investigated at 77 K using high-resolution neutron powder diffraction. Rietveld refinement of the neutron data revealed a sequential filling of the rigid framework at distinct preferred adsorption sites, and showed the importance of

  14. Preferred orientation of a naturally and experimentally deformed pyrrhotite ore by X-ray and neutron diffraction texture analysis

    International Nuclear Information System (INIS)

    Niederschlag, E.; Brokmeier, H.G.; Siemes, H.

    1994-01-01

    Two samples of polycrystalline naturally deformed hexagonal Pyrrhotite were deformed experimentally in axial compression tests with different temperatures and strain. The texture of the naturally deformed ore was investigated both by X-ray and neutron texture analyses. Texture measurements on the experimentally deformed ore were carried out by neutron diffraction. (orig.)

  15. Historical review of neutron spectrometry and diffraction in Brazil - 50 years

    International Nuclear Information System (INIS)

    Voi, Dante L.; Ferreira, Francisco J.O.; Stasiulevicius, Roberto; Rodrigues, Claudio; Parente, Carlos B.R.; Mazzocchi, Vera L.; Mestnik Filho, Jose; Pugliesi, Reinaldo

    2011-01-01

    Neutron Spectrometry and Diffraction techniques began to be studied in Brazil with the construction of the first research reactors in the years 50 and 60, and were developed with the participation of national and international scientists. In particular, we note the perseverance of the Brazilian pioneer of nuclear energy, Dr. Marcello Damy de Souza Santos, and from that time, with the involvement of some of the early pioneers, such as the physicist Roberto Stasiulevicius, who had the privilege of working in all three Brazilian nuclear research reactors. All these scientists shared half a century of acquired knowledge, helping in the training of a number of experts who are now working in national and international nuclear institutes. The present work reviews in chronological order, the testimony of the historical facts associated with the development and application of experimental techniques using neutrons as a tool for materials analysis and studies for many areas of the sciences and also with the training of personnel. IPEN, IEN and CDTN, all institutes of the CNEN-Brazil, are important in the national and international scene as a result of the research carried out there and the large number of publications produced in the field of neutron spectrometry and diffraction from experimental work carried out using the IEA (5MW), Argonauta (5kW) and more recently, the IPR (250kW) research reactors. An extensive bibliography is also presented and this can be disseminated to everyone interested. (author)

  16. An in situ thermo-mechanical rig for lattice strain measurement during creep using neutron diffraction

    Science.gov (United States)

    Wang, Y. Q.; Kabra, S.; Zhang, S. Y.; Truman, C. E.; Smith, D. J.

    2018-05-01

    A long-term high-temperature testing stress rig has been designed and fabricated for performing in situ neutron diffraction tests at the ENGIN-X beamline, ISIS facility in the UK. It is capable of subjecting metals to high temperatures up to 800 °C and uniaxial loading under different boundary conditions including constant load, constant strain, and elastic follow-up, each with minimum of external control. Samples are held horizontally between grips and connected to a rigid rig frame, a soft aluminium bar, and a stepper motor with forces up to 20 kN. A new three zone split electrical resistance furnace which generates a stable and uniform heat atmosphere over 200 mm length was used to heat the samples. An 8 mm diameter port at 45° to the centre of the furnace was made in order to allow the neutron beam through the furnace to illuminate the sample. The entire instrument is mounted on the positioner at ENGIN-X and has the potential ability to operate continuously while being moved in and out of the neutron diffraction beam. The performance of the rig has been demonstrated by tracking the evolution of lattice strains in type 316H stainless steel under elastic follow-up control at 550 °C.

  17. Kinetic studies of methane-ethane mixed gas hydrates by neutron diffraction and Raman spectroscopy.

    Science.gov (United States)

    Murshed, M Mangir; Kuhs, Werner F

    2009-04-16

    In situ formations of CH(4)-C(2)H(6) mixed gas hydrates were made using high flux neutron diffraction at 270 K and 5 MPa. For this purpose, a feed gas composition of CH(4) and C(2)H(6) (95 mol% CH(4)) was employed. The rates of transformation of spherical grains of deuterated ice Ih into hydrates were measured by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. Phase fractions of the crystalline constituents were obtained from Rietveld refinements. A concomitant formation of structure type I (sI) and structure type II (sII) hydrates were observed soon after the gas pressure was applied. The initial fast formation of sII hydrate reached its maximum volume and started declining very slowly. The formation of sI hydrate followed a sigmoid growth kinetics that slowed down due to diffusion limitation. This observation has been interpreted in terms of a kinetically favored nucleation of the sII hydrate along with a slow transformation into sI. Both powder diffraction and Raman spectroscopic results suggest that a C(2)H(6)-rich sII hydrate was formed at the early part of the clathration, which slowly decreased to approximately 3% after a reaction of 158 days as confirmed by synchrotron XRD. The final persistence of a small portion of sII hydrate points to a miscibility gap between CH(4)-rich sI and C(2)H(6)-rich sII hydrates.

  18. Neutron diffraction studies on lattice strain evolution around a crack-tip during tensile loading and unloading cycles

    Energy Technology Data Exchange (ETDEWEB)

    Sun Yinan [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States)]. E-mail: ysun1@utk.edu; Choo, Hahn [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Liaw, Peter K. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Lu Yulin [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Yang Bing [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Brown, Donald W. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bourke, Mark A.M. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2005-10-15

    Elastic lattice-strain profiles ahead of a fatigue-crack-tip were measured during tensile loading and unloading cycles using neutron diffraction. The crack-closure phenomenon after an overload was observed. Furthermore, the plastic-zone size in front of the crack-tip was estimated from the diffraction-peak broadening, which showed good agreement with the calculated result.

  19. Thermal neutron filter design for the neutron radiography facility at the LVR-15 reactor

    Energy Technology Data Exchange (ETDEWEB)

    Soltes, Jaroslav [Research Centre Rez Ltd., Husinec - Rez 130, 250 68 Rez, (Czech Republic); Faculty of Nuclear Sciences and Physical Engineering, CTU in Prague, (Czech Republic); Viererbl, Ladislav; Lahodova, Zdena; Koleska, Michal; Vins, Miroslav [Research Centre Rez Ltd., Husinec - Rez 130, 250 68 Rez, (Czech Republic)

    2015-07-01

    In 2011 a decision was made to build a neutron radiography facility at one of the unused horizontal channels of the LVR-15 research reactor in Rez, Czech Republic. One of the key conditions for operating an effective radiography facility is the delivery of a high intensity, homogeneous and collimated thermal neutron beam at the sample location. Additionally the intensity of fast neutrons has to be kept as low as possible as the fast neutrons may damage the detectors used for neutron imaging. As the spectrum in the empty horizontal channel roughly copies the spectrum in the reactor core, which has a high ratio of fast neutrons, neutron filter components have to be installed inside the channel in order to achieve desired beam parameters. As the channel design does not allow the instalment of complex filters and collimators, an optimal solution represent neutron filters made of large single-crystal ingots of proper material composition. Single-crystal silicon was chosen as a favorable filter material for its wide availability in sufficient dimensions. Besides its ability to reasonably lower the ratio of fast neutrons while still keeping high intensities of thermal neutrons, due to its large dimensions, it suits as a shielding against gamma radiation from the reactor core. For designing the necessary filter dimensions the Monte-Carlo MCNP transport code was used. As the code does not provide neutron cross-section libraries for thermal neutron transport through single-crystalline silicon, these had to be created by approximating the theory of thermal neutron scattering and modifying the original cross-section data which are provided with the code. Carrying out a series of calculations the filter thickness of 1 m proved good for gaining a beam with desired parameters and a low gamma background. After mounting the filter inside the channel several measurements of the neutron field were realized at the beam exit. The results have justified the expected calculated values

  20. Thermal neutron scattering studies of condensed matter under high pressures

    International Nuclear Information System (INIS)

    Carlile, C.J.; Salter, D.C.

    1978-01-01

    Although temperature has been used as a thermodynamic variable for samples in thermal neutron scattering experiments since the inception of the neutron technique, it is only in the last decade that high pressures have been utilised for this purpose. In the paper the problems particular to this field of work are outlined and a review is made of the types of high-pressure cells used and the scientific results obtained from the experiments. 103 references. (author)

  1. Determination of thermal neutrons diffusion length in graphite

    International Nuclear Information System (INIS)

    Garcia Fite, J.

    1959-01-01

    The diffusion length of thermal neutrons in graphite using the less possible quantity of material has been determined. The proceeding used was the measurement in a graphite pile which has a punctual source of rapid neutrons inside surrounded by a reflector medium (paraffin or water). The measurement was done in the following conditions: a) introducing an aluminium plate between both materials. b) Introducing a cadmium plate between both materials. (Author) 91 refs

  2. High pressure neutron and X-ray diffraction at low temperatures

    International Nuclear Information System (INIS)

    Ridley, Christopher J.; Kamenev, Konstantin V.

    2014-01-01

    This paper presents a review of techniques and considerations in the design and construction of high pressure, low temperature diffraction experiments. Also intended as an introductory text to new high pressure users, the crucial aspects of pressure cell design are covered. The general classification of common designs, and a discussion into the key beam interaction, mechanical, and thermal properties of commonly used materials is given. The advantages of different materials and high pressure cell classifications are discussed, and examples of designs developed for low temperature diffraction studies are presented, and compared. (orig.)

  3. High pressure neutron and X-ray diffraction at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ridley, Christopher J.; Kamenev, Konstantin V. [Edinburgh Univ. (United Kingdom). School of Engineering and the Centre for Science at Extreme Conditions

    2014-04-01

    This paper presents a review of techniques and considerations in the design and construction of high pressure, low temperature diffraction experiments. Also intended as an introductory text to new high pressure users, the crucial aspects of pressure cell design are covered. The general classification of common designs, and a discussion into the key beam interaction, mechanical, and thermal properties of commonly used materials is given. The advantages of different materials and high pressure cell classifications are discussed, and examples of designs developed for low temperature diffraction studies are presented, and compared. (orig.)

  4. Dosimetry in Thermal Neutron Irradiation Facility at BMRR

    Directory of Open Access Journals (Sweden)

    Hu J.-P.

    2016-01-01

    Full Text Available Radiation dosimetry for Neutron Capture Therapy (NCT has been performed since 1959 at Thermal Neutron Irradiation Facility (TNIF of the three-megawatt light-water cooled Brookhaven Medical Research Reactor (BMRR. In the early 1990s when more effective drug carriers were developed for NCT, in which the eye melanoma and brain tumors in rats were irradiated in situ, extensive clinical trials of small animals began using a focused thermal neutron beam. To improve the dosimetry at irradiation facility, a series of innovative designs and major modifications made to enhance the beam intensity and to ease the experimental sampling at BMRR were performed; including (1 in-core fuel addition to increase source strength and balance flux of neutrons towards two ports, (2 out of core moderator remodeling, done by replacing thicker D2O tanks at graphite-shutter interfacial areas, to expedite neutron thermalization, (3 beam shutter upgrade to reduce strayed neutrons and gamma dose, (4 beam collimator redesign to optimize the beam flux versus dose for animal treatment, (5 beam port shielding installation around the shutter opening area (lithium-6 enriched polyester-resin in boxes, attached with polyethylene plates to reduce prompt gamma and fast neutron doses, (6 sample holder repositioning to optimize angle versus distance for a single organ or whole body irradiation, and (7 holder wall buildup with neutron reflector materials to increase dose and dose rate from scattered thermal neutrons. During the facility upgrade, reactor dosimetry was conducted using thermoluminescent dosimeters TLD for gamma dose estimate, using ion chambers to confirm fast neutron and gamma dose rate, and by the activation of gold-foils with and without cadmium-covers, for fast and thermal neutron flux determination. Based on the combined effect from the size and depth of tumor cells and the location and geometry of dosimeters, the measured flux from cadmium-difference method was 4–7

  5. Dosimetry in Thermal Neutron Irradiation Facility at BMRR

    Energy Technology Data Exchange (ETDEWEB)

    Hu, J. P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Holden, N. E. [Brookhaven National Lab. (BNL), Upton, NY (United States); Reciniello, R. N.

    2014-05-23

    Radiation dosimetry for Neutron Capture Therapy (NCT) has been performed since 1959 at Thermal Neutron Irradiation Facility (TNIF) of the three-megawatt light-water cooled Brookhaven Medical Research Reactor (BMRR). In the early 1990s when more effective drug carriers were developed for NCT, in which the eye melanoma and brain tumors in rats were irradiated in situ, extensive clinical trials of small animals began using a focused thermal neutron beam. To improve the dosimetry at irradiation facility, a series of innovative designs and major modifications made to enhance the beam intensity and to ease the experimental sampling at BMRR were performed; including (1) in-core fuel addition to increase source strength and balance flux of neutrons towards two ports, (2) out of core moderator remodeling, done by replacing thicker D2O tanks at graphite-shutter interfacial areas, to expedite neutron thermalization, (3) beam shutter upgrade to reduce strayed neutrons and gamma dose, (4) beam collimator redesign to optimize the beam flux versus dose for animal treatment, (5) beam port shielding installation around the shutter opening area (lithium-6 enriched polyester-resin in boxes, attached with polyethylene plates) to reduce prompt gamma and fast neutron doses, (6) sample holder repositioning to optimize angle versus distance for a single organ or whole body irradiation, and (7) holder wall buildup with neutron reflector materials to increase dose and dose rate from scattered thermal neutrons. During the facility upgrade, reactor dosimetry was conducted using thermoluminescent dosimeters TLD for gamma dose estimate, using ion chambers to confirm fast neutron and gamma dose rate, and by the activation of gold-foils with and without cadmium-covers, for fast and thermal neutron flux determination. Based on the combined effect from the size and depth of tumor cells and the location and geometry of dosimeters, the measured flux from cadmium-difference method was 4 - 7

  6. Method and apparatus for measuring thermal neutron characteristics

    International Nuclear Information System (INIS)

    Johnstone, C.W.

    1983-01-01

    The thermal neutron decay characteristics of an earth formation are measured by detecting indications of the thermal neutron concentration in the formation during a selected set of two measurement intervals following irradiation of the formation with a burst of fast neutrons. These measurement intervals may comprise a sequence of time gates following a delay after the neutron burst. The duration of the neutron bursts, of the delay between the burst and the start of the sequence, and of the individual time gates, may all be adjusted by a common, selected one of a finite number of scale factor values. The set of two measurement intervals is selected from among a number of possible sets as a function of a previously measured value of the decay characteristic. Each measurement interval set is used over only a specific range of decay characteristic values for which it has been determined, in accordance with a previously established relationship between the decay characteristic value and a function of the thermal neutron concentration measurements for the set, to afford enhanced statistical accuracy in the measured value of the decay characteristic. (author)

  7. Introduction to the theory of thermal neutron scattering

    CERN Document Server

    Squires, G L

    2012-01-01

    Since the advent of the nuclear reactor, thermal neutron scattering has proved a valuable tool for studying many properties of solids and liquids, and research workers are active in the field at reactor centres and universities throughout the world. This classic text provides the basic quantum theory of thermal neutron scattering and applies the concepts to scattering by crystals, liquids and magnetic systems. Other topics discussed are the relation of the scattering to correlation functions in the scattering system, the dynamical theory of scattering and polarisation analysis. No previous knowledge of the theory of thermal neutron scattering is assumed, but basic knowledge of quantum mechanics and solid state physics is required. The book is intended for experimenters rather than theoreticians, and the discussion is kept as informal as possible. A number of examples, with worked solutions, are included as an aid to the understanding of the text.

  8. Targets for bulk hydrogen analysis using thermal neutrons

    CERN Document Server

    Csikai, J; Buczko, C M

    2002-01-01

    The reflection property of substances can be characterized by the reflection cross-section of thermal neutrons, sigma subbeta. A combination of the targets with thin polyethylene foils allowed an estimation of the flux depression of thermal neutrons caused by a bulk sample containing highly absorbing elements or compounds. Some new and more accurate sigma subbeta values were determined by using the combined target arrangement. For the ratio, R of the reflection and the elastic scattering cross-sections of thermal neutrons, R=sigma subbeta/sigma sub E sub L a value of 0.60+-0.02 was found on the basis of the data obtained for a number of elements from H to Pb. Using this correlation factor, and the sigma sub E sub L values, the unknown sigma subbeta data can be deduced. The equivalent thicknesses, to polyethylene or hydrogen, of the different target materials were determined from the sigma subbeta values.

  9. Thermal neutron dose calculation in synovium membrane for BNCS

    International Nuclear Information System (INIS)

    Abdalla, Khalid; Naqvi, A.A.; Maalej, N.; El-Shahat, B.

    2006-01-01

    A D(d,n) reaction based setup has been optimized for Boron Neutron Capture Synovectomy (BNCS). The polyethylene moderator and graphite reflector sizes were optimized to deliver the highest ratio of thermal to fast neutron yield. The neutron dose was calculated at various depths in a knee phantom loaded with boron to determine therapeutic ratios of synovium dose/skin dose and synovium dose/bone dose. Normalized to same boron loading in synovium, the values of the therapeutic ratios obtained in the present study are 12-30 times higher than the published values. (author)

  10. Improvement of neutron collimator design for thermal neutron radiography using Monte Carlo N-particle transport code version 5

    International Nuclear Information System (INIS)

    Thiagu Supramaniam

    2007-01-01

    The aim of this research was to propose a new neutron collimator design for thermal neutron radiography facility using tangential beam port of PUSPATI TRIGA Mark II reactor, Malaysia Institute of Nuclear Technology Research (MINT). Best geometry and materials for neutron collimator were chosen in order to obtain a uniform beam with maximum thermal neutron flux, high L/ D ratio, high neutron to gamma ratio and low beam divergence with high resolution. Monte Carlo N-particle Transport Code version 5 (MCNP 5) was used to optimize six neutron collimator components such as beam port medium, neutron scatterer, neutron moderator, gamma filter, aperture and collimator wall. The reactor and tangential beam port setup in MCNP5 was plotted according to its actual sizes. A homogeneous reactor core was assumed and population control method of variance reduction technique was applied by using cell importance. The comparison between experimental results and simulated results of the thermal neutron flux measurement of the bare tangential beam port, shows that both graph obtained had similar pattern. This directly suggests the reliability of MCNP5 in order to obtained optimal neutron collimator parameters. The simulated results of the optimal neutron medium, shows that vacuum was the best medium to transport neutrons followed by helium gas and air. The optimized aperture component was boral with 3 cm thickness. The optimal aperture center hole diameter was 2 cm which produces 88 L/ D ratio. Simulation also shows that graphite neutron scatterer improves thermal neutron flux while reducing fast neutron flux. Neutron moderator was used to moderate fast and epithermal neutrons in the beam port. Paraffin wax with 90 cm thick was bound to be the best neutron moderator material which produces the highest thermal neutron flux at the image plane. Cylindrical shape high density polyethylene neutron collimator produces the highest thermal neutron flux at the image plane rather than divergent

  11. Assessment of Shape Memory Alloys - From Atoms To Actuators - Via In Situ Neutron Diffraction

    Science.gov (United States)

    Benafan, Othmane

    2014-01-01

    As shape memory alloys (SMAs) become an established actuator technology, it is important to identify the fundamental mechanisms responsible for their performance by understanding microstructure performance relationships from processing to final form. Yet, microstructural examination of SMAs at stress and temperature is often a challenge since structural changes occur with stress and temperature and microstructures cannot be preserved through quenching or after stress removal, as would be the case for conventional materials. One solution to this dilemma is in situ neutron diffraction, which has been applied to the investigation of SMAs and has offered a unique approach to reveal the fundamental micromechanics and microstructural aspects of bulk SMAs in a non-destructive setting. Through this technique, it is possible to directly correlate the micromechanical responses (e.g., internal residual stresses, lattice strains), microstructural evolutions (e.g., texture, defects) and phase transformation properties (e.g., phase fractions, kinetics) to the macroscopic actuator behavior. In this work, in situ neutron diffraction was systematically employed to evaluate the deformation and transformation behavior of SMAs under typical actuator conditions. Austenite and martensite phases, yield behavior, variant selection and transformation temperatures were characterized for a polycrystalline NiTi (49.9 at. Ni). As the alloy transforms under thermomechanical loading, the measured textures and lattice plane-level variations were directly related to the cyclic actuation-strain characteristics and the dimensional instability (strain ratcheting) commonly observed in this alloy. The effect of training on the shape memory characteristics of the alloy and the development of two-way shape memory effect (TWSME) were also assessed. The final conversion from a material to a useful actuator, typically termed shape setting, was also investigated in situ during constrained heatingcooling and

  12. Perdeuteration, purification, crystallization and preliminary neutron diffraction of an ocean pout type III antifreeze protein

    International Nuclear Information System (INIS)

    Petit-Haertlein, Isabelle; Blakeley, Matthew P.; Howard, Eduardo; Hazemann, Isabelle; Mitschler, Andre; Haertlein, Michael; Podjarny, Alberto

    2009-01-01

    Perdeuterated type III antifreeze protein has been expressed, purified and crystallized. Preliminary neutron data collection showed diffraction to 1.85 Å resolution from a 0.13 mm 3 crystal. The highly homologous type III antifreeze protein (AFP) subfamily share the capability to inhibit ice growth at subzero temperatures. Extensive studies by X-ray crystallography have been conducted, mostly on AFPs from polar fishes. Although interactions between a defined flat ice-binding surface and a particular lattice plane of an ice crystal have now been identified, the fine structural features underlying the antifreeze mechanism still remain unclear owing to the intrinsic difficulty in identifying H atoms using X-ray diffraction data alone. Here, successful perdeuteration (i.e. complete deuteration) for neutron crystallographic studies of the North Atlantic ocean pout (Macrozoarces americanus) AFP in Escherichia coli high-density cell cultures is reported. The perdeuterated protein (AFP D) was expressed in inclusion bodies, refolded in deuterated buffer and purified by cation-exchange chromatography. Well shaped perdeuterated AFP D crystals have been grown in D 2 O by the sitting-drop method. Preliminary neutron Laue diffraction at 293 K using LADI-III at ILL showed that with a few exposures of 24 h a very low background and clear small spots up to a resolution of 1.85 Å were obtained using a ‘radically small’ perdeuterated AFP D crystal of dimensions 0.70 × 0.55 × 0.35 mm, corresponding to a volume of 0.13 mm 3

  13. Preliminary neutron diffraction analysis of challenging human manganese superoxide dismutase crystals.

    Science.gov (United States)

    Azadmanesh, Jahaun; Trickel, Scott R; Weiss, Kevin L; Coates, Leighton; Borgstahl, Gloria E O

    2017-04-01

    Superoxide dismutases (SODs) are enzymes that protect against oxidative stress by dismutation of superoxide into oxygen and hydrogen peroxide through cyclic reduction and oxidation of the active-site metal. The complete enzymatic mechanisms of SODs are unknown since data on the positions of hydrogen are limited. Here, methods are presented for large crystal growth and neutron data collection of human manganese SOD (MnSOD) using perdeuteration and the MaNDi beamline at Oak Ridge National Laboratory. The crystal from which the human MnSOD data set was obtained is the crystal with the largest unit-cell edge (240 Å) from which data have been collected via neutron diffraction to sufficient resolution (2.30 Å) where hydrogen positions can be observed.

  14. Extra spots in the electron diffraction patterns of neutron irradiated zirconium and its alloys

    International Nuclear Information System (INIS)

    Madden, P.K.

    1977-01-01

    Specimens of neutron irradiated zirconium and its alloys were examined in the transmission electron microscope. Groups of extra spots, often exhibiting four-fold symmetry, were observed in thin foil electron diffraction patterns of these specimens. The 'extra-spot' structure, like the expected black-dot/small scale dislocation loop neutron irradiated damage, is approximately 100 A in size. Its nature is uncertain. It may be related to irradiation damage or to some artefact introduced during specimen preparation. If it is the latter, then published irradiation damage defect size distributions and determined irradiation growth strains of other investigators, may require modification. The present inconclusive results indicate that extra-spot structure is likely to consist of oxide particles, but may correspond to hydride precipitation or decoration effects, or even, to electron beam effects. (author)

  15. Neutron diffraction potentialities at the IBR-2 pulsed reactor for nondestructive testing of structural materials

    International Nuclear Information System (INIS)

    Balagurov, A.M.; Bokuchava, G.D.; Papushkin, I.V.; Sumin, V.V.; Venter, A.M.

    2010-01-01

    Neutron diffraction is widely used for investigations of residual and applied stresses in bulk materials and components. The most important factor in these investigations is the high penetration depth of neutrons (up to 2 cm for steel). At the IBR-2 pulsed reactor in Dubna the Fourier stress diffractometer (FSD) has been constructed to optimize the internal stress measurements. The FSD design satisfies the requirements of high luminosity, high resolution and specific sample environment. The collimator system guarantees a minimum gauge volume of 2x2x2 mm. A mechanical testing machine allows in-situ tension or compression measurements up to a load of 20 kN and sample temperatures up to 800 deg C. In the paper the current status of FSD is reported and potentialities are demonstrated with several examples of investigations performed

  16. X-ray and neutron diffraction and molecular dynamics simulation of molten lithium and rubidium nitrates

    International Nuclear Information System (INIS)

    Yamaguchi, Toshio; Okada, Isao; Ohtaki, Hitoshi; Mikami, Masuhiro; Kawamura, Kazutaka

    1986-01-01

    Molecular dynamics simulations have been performed for lithium and rubidium nitrate melts at 550 and 600K, respectively, together with X-ray and neutron diffraction experiments. Simple Coulomb pair potentials with Born-type repulsions have been adopted in the simulations with a rigid body model for the nitrate ion. Structure functions derived from the X-ray and neutron experiments are well reproduced by the simulations, from which the three-dimensional cation distribution around the nitrate ion has been revealed. The self-diffusion coefficients, the velocity autocorrelation functions and the self-exchange velocities of lithium, rubidium and nitrate ions have been calculated. Anisotropic motion of nitrate ions has been found and is discussed on the basis of the structure of the melts. (author)

  17. Measurement of residual strain in composites by means of time-of- flight neutron diffraction

    International Nuclear Information System (INIS)

    Kupperman, D.S.; Majumdar, S.; Richardson, J.; Saigal, A.

    1993-01-01

    Neutron diffraction time-of-flight measurements using the Intense Pulsed Neutron Source at Argonne National Laboratory have been employed to study strain in various metal- and ceramic-matrix composites. For example, measurements carried out to 900 C on a composite composed of a titanium alloy matrix and silicon carbide fibers have been used to validate theoretical assumptions in the prediction of fabrication-induced residual stress. Sapphire reinforced nickel aluminide composites have also been studied. Studies of a high-temperature ceramic superconducting composite consisting of yttrium barium copper oxide and silver with various volume fractions of silver have also been carried out. The results of these studies have provided information on the effect of Ag content on interface bonding. In addition, ceramic-matrix composites with randomly dispersed ceramic whiskers with varying fiber content have been investigated

  18. Status of thermal neutron scattering data for graphite

    International Nuclear Information System (INIS)

    Mattes, M.; Keinert, J.

    2005-07-01

    At thermal neutron energies, the binding of the scattering nucleus in a solid, liquid, or gas affects the cross sections and the angular and energy distributions of the scattered neutrons. These effects are described in the thermal sub-library of evaluated files in File 7 of the ENDF-6 format. A re-evaluation of thermal neutron scattering data for carbon bound in graphite has been performed to investigate the impact of models (e.g., generalised frequency distributions) based on different experimental and theoretical data for the generation of scattering law data files S(α,β,T) and coherent elastic scattering data. Two phonon frequency distributions of graphite published in 2002 and 2004 were considered and the results compared with those based on the phonon spectra from Koppel et al. (published in 1968), on which the evaluations of ENDF/B-VI and JEFF-3.1 are based. The new frequency distributions were partly derived from ab initio simulations. Detailed comparisons with measurements of differential and integral neutron cross sections and other relevant data are reported. In addition, thermal MCNP data sets for use in the continuous Monte Carlo codes MCNP and MCNPX were generated from these evaluations for different temperatures. Calculated neutron spectra were found to be in good agreement with the measurements. (author)

  19. Comparison of neutron and synchrotron diffraction measurements of residual stress in bead-on-plate weldments

    International Nuclear Information System (INIS)

    Paradowska, A.M.; Price, J.W.; Finlayson, T.R.; Lienert, U.; Ibrahim, R.

    2010-01-01

    This paper explores the use of neutron and synchrotron diffractions for the evaluation of residual stresses in welded components. It has been shown that it is possible to achieve very good agreement between the two independent diffraction techniques. This study shows the significance of the weld start and end sites on the residual strain/stress distribution. Quantitative evaluation of the residual stress development process for multibead weldments has been presented. Some measurements were also taken before and after postweld stress relieving to establish the reduction and redistribution of the residual stress. The detailed measurements of residual stress around the weld achieved in this work significantly improve the knowledge and understanding of residual stress in welded components.

  20. Integrated intensities and flipping ratios in neutron diffraction by perfect magnetic crystals

    International Nuclear Information System (INIS)

    Guigay, J.P.; Schlenker, M.

    1979-01-01

    A theoretical study of neutron diffraction by perfect magnetic crystals is presented which shows that when the magnetization is perpendicular to the diffraction vector (β- π/2), the dispersion surface is made up of two hyperbolic surfaces corresponding to simple polarization states and the results of the two-beam dynamical theory for non-magnetic crystals can be directly applied. The asymptotic properties of the dispersion surface are of the dispersion surface are also discussed in the more general case (β is not equal to π/2) and an analytical treatment of the kinematical limit is presented. Integrated intensities and flipping ratios outside this limit can only be calculated numerically. It is shown that the wave fields defined by the different points of the dispersion surface are polarized in the (g, B 0 ) plane; this is a generalization of the fact that they are (+-) states with respect to B 0 in the simple case (β=π/2). (UK)

  1. Structure of molten TbCl sub 3 measured by neutron diffraction

    CERN Document Server

    Martin, R A; Barnes, A C; Cuello, G J

    2002-01-01

    The total structure factor of molten TbCl sub 3 at 617 deg. C was measured by using neutron diffraction. The data are in agreement with results from previous experimental work but the use of a diffractometer having an extended reciprocal-space measurement window leads to improved resolution in real space. Significant discrepancies with the results obtained from recent molecular dynamics simulations carried out using a polarizable ion model, in which the interaction potentials were optimized to enhance agreement with previous diffraction data, are thereby highlighted. It is hence shown that there is considerable scope for the development of this model for TbCl sub 3 and for other trivalent metal halide systems spanning a wide range of ion size ratios. (letter to the editor)

  2. Refinement of the ferri and paramagnetic phases of magnetite measured by neutron multiple diffraction

    International Nuclear Information System (INIS)

    Mazzochi, V.L.; Parente, C.B.R.

    1989-10-01

    Structural parameters of the ferri and paramagnetic phases of magnetite have been refined from neutron multiple diffraction data. Experimental patterns were obtained by measuring the III primary reflection of a natural single crystal of this compound, at room temperature for the ferrimagnetic phase and 703 0 C for the paramagnetic phase. Theoretical multiple diffraction patterns for both phases have been calculated by the program MULTI which uses the iterative method. In this method intensities are caluclated as Taylor series expansions summed up to a order sufficient for a good approximation. A step by step process has been used in the refinements similarly to the parameter-shift method. Final values for the discrepancy factor found for the ferri and paramagnetic phases were R = 3.96% and R = 3.46%, respectively. (author) [pt

  3. Discussion on accuracy of weld residual stress measurement by neutron diffraction. Influence of strain free reference

    International Nuclear Information System (INIS)

    Suzuki, Hiroshi; Akita, Koichi

    2012-01-01

    It is required to evaluate a strain-free reference, α 0 , to perform accurate stress measurement using neutron diffraction. In this study, accuracy of neutron stress measurement was quantitatively discussed from α 0 evaluations on a dissimilar metal butt-weld between a type 304 austenitic stainless steel and an A533B low alloy ferritic steel. A strain-free standard specimen and a sliced specimen with 10 mm thickness taken from the dissimilar metal butt-weld were utilized. In the lattice constant evaluation using the standard specimen, average lattice constant derived from multiple hkl reflections was evaluated as the stress-free reference with cancelling out an intergranular strain. Comparing lattice constant distributions in each reflection with average lattice constant distribution in the standard specimen, αFe211 and γFe311 reflections were judged as a suitable reflection for neutron strain measurement to reduce intergranular strain effects. Residual stress distribution in the sliced specimen evaluated using α 0 measured here exhibited higher accuracy than that measured using strain gauges. On the other hand, α 0 distributions were evaluated using the sliced specimen under the plane-stress condition. Existence of slight longitudinal residual stresses near the weld center decreased accuracy of the α 0 evaluations, which means that it is required to optimize the thickness of the sliced specimen for accurate α 0 evaluation under plane strain condition. As a conclusion of this study, it was confirmed that procedures of accurate α 0 evaluation, optimization of the measurement condition, and multiple evaluations on the results play an important role to improve accuracy of the residual stress measurement using neutron diffraction. (author)

  4. Residual Stress Distribution In Heat Affected Zone Of Welded Steel By Means Of Neutron Diffraction Method

    International Nuclear Information System (INIS)

    Fajar, Andika; Prasuad; Gunawan; Muslich, M. Rifai

    1996-01-01

    Three dimensional residual stress distribution in the heat affected zone of 10 mm thick welded steel by means of neutron diffraction technique has been measured. The results showed that the residual stress was distributed near the welded metal, namely within about 46,25 mm. The major tensile stresses occurred in the X-direction, and they attained a level greater than 2000 MPa through the position far away fram the weld. The tensile stresses in the Y and Z- directions lied between 500 and 1500 MPa, The results also suggest that the stress in the surface was greater than that in the middle of the sample

  5. Data analysis of a polycrystalline nickel sample obtained with neutron diffraction

    International Nuclear Information System (INIS)

    Parente, C.B.R.; Mazzochi, V.L.; Araujo Kaschny, J.R. de; Costa, M.S. da; Rizzo, P.; Campos, W.M.S.

    1990-01-01

    A simple analysis of the nickel structure was made. Neutron diffraction data were used, obtained with polycrystalline nickel placed in a cylindrical sample-holder with dimensions of 1,5cm of diameter and 5cm of height. The theoretical intensities were calculated of 3 forms: 1. without considering the temperature and obsorption effects, 2. considering only the temperature effect and 3. considering both the temperature and absorption effects. The disagreement factors found in this 3 cases were, respectively, R 1 = 13.4%, R 2 = 7,7% e R 3 = 7,5%. (L.C.)

  6. In-situ neutron diffraction study of Zircaloy 4 subjected to biaxial tension

    Energy Technology Data Exchange (ETDEWEB)

    Gharghouri, M.A. [Canadian Neutron Beam Centre, Chalk River Laboratories, Chalk River, ON (Canada); McDonald, D.; Xiao, L. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

    2014-07-01

    Zircaloy-4 is widely used as fuel element cladding in nuclear reactors. Pellet-clad interaction (PCI) failure is a concern for many water reactor fuel designs. Extensive work on the mechanism of PCI failure has led to the conclusion that stress corrosion cracking (SCC) induced by iodine vapour in the temperature range relevant to fuel operation is the most probable cause of PCI failure in zirconium alloy fuel element cladding. In-situ neutron diffraction measurements performed on tubular Zircaloy-4 specimens simultaneously pulled in tension and pressurized internally will provide information on the effects of stress biaxiality on the distribution of stresses at the crystal level during loading. (author)

  7. Neutron-Diffraction Study of the Phase Transition in Stannous Chloride Dihydrate

    DEFF Research Database (Denmark)

    Youngblood, R.; Kjems, Jørgen

    1979-01-01

    of the system does not change. We present neutron-diffraction results which show that the temperature dependence of the hydrogen-site occupancies is also highly symmetric around the phase-transition temperature. These results are discussed in terms of a lattice statistical model which was proposed and solved......The order-disorder phase transition in two-dimensional hydrogen-bonded layers of water molecules in SnCl2·2D2O is remarkable in several respects. It has been shown that the peak in the specific heat is highly symmetric around the phase-transition temperature, and that the crystallographic symmetry...

  8. On the atomic structure of liquid Ni-Si alloys: a neutron diffraction study

    Science.gov (United States)

    Gruner, S.; Marczinke, J.; Hennet, L.; Hoyer, W.; Cuello, G. J.

    2009-09-01

    The atomic structure of the liquid NiSi and NiSi2 alloys is investigated by means of neutron diffraction experiments with isotopic substitution. From experimental data-sets obtained using four Ni isotopes, partial structure factors and pair correlation functions are obtained by applying a reverse Monte Carlo modelling approach. Both alloys were found to exhibit a strong tendency to hetero-coordination within the first coordination shell. In particular, covalent Si-Si bonds with somewhat greater distances seem to influence the structure of the liquid NiSi alloy.

  9. On the atomic structure of liquid Ni-Si alloys: a neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Gruner, S; Marczinke, J; Hoyer, W [Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz (Germany); Hennet, L [CNRS-CEMHTI, University of Orleans, F-45071 Orleans (France); Cuello, G J, E-mail: sascha.gruner@physik.tu-chemnitz.d [Institute Laue-Langevin, PO Box 156, F-38042 Grenoble (France)

    2009-09-23

    The atomic structure of the liquid NiSi and NiSi{sub 2} alloys is investigated by means of neutron diffraction experiments with isotopic substitution. From experimental data-sets obtained using four Ni isotopes, partial structure factors and pair correlation functions are obtained by applying a reverse Monte Carlo modelling approach. Both alloys were found to exhibit a strong tendency to hetero-coordination within the first coordination shell. In particular, covalent Si-Si bonds with somewhat greater distances seem to influence the structure of the liquid NiSi alloy.

  10. Structures of high and low density amorphous ice by neutron diffraction

    International Nuclear Information System (INIS)

    Finney, J.L.; Hallbrucker, A.; Kohl, I.; Soper, A.K.; Bowron, D.T.

    2002-01-01

    Neutron diffraction with isotope substitution is used to determine the structures of high (HDA) and low (LDA) density amorphous ice. Both 'phases' are fully hydrogen bonded, tetrahedral networks, with local order similarities between LDA and ice Ih, and HDA and liquid water. Moving from HDA, through liquid water and LDA to ice Ih, the second shell radial order increases at the expense of spatial order. This is linked to a fifth first neighbor 'interstitial' that restricts the orientations of first shell waters. This 'lynch pin' molecule which keeps the HDA structure intact has implications for the nature of the HDA-LDA transition that bear on the current metastable water debate

  11. High resolution neutron diffraction crystallographic investigation of Oxide Dispersion Strengthened steels of interest for fusion technology

    International Nuclear Information System (INIS)

    Coppola, R.; Rodriguez-Carvajal, J.; Wang, M.; Zhang, G.; Zhou, Z.

    2014-01-01

    High resolution neutron diffraction measurements have been carried out to characterize the crystallographic phases present in different Oxide Dispersion Strengthened (ODS) steels of interest for fusion technology. The different lattice structures, Im3m for the ferritic ODS and Fm3m for the austenitic ODS, are resolved showing line anisotropy effects possibly correlated with differences in dislocation densities and texture. Many contributions from minority phases are detected well above the background noise; none of the expected crystallographic phases, such as M 23 C 6 and including Y 2 O 3 , fits them, but the TiN phase is identified in accordance with results of other microstructural techniques

  12. Neutron diffraction structure investigations for expanded liquid selenium up to 14000C and 300 bar

    International Nuclear Information System (INIS)

    Edeling, M.

    1980-01-01

    The static structure factor of the expanded liquid Selenium is measured by means of the neutron diffraction for temperatures between 600 0 C and 1400 0 C and for pressures up to 300 bar. From the structure factors the pair distribution functions show that the bond length of the Selenium atoms is constant 2.37 A to 2.38 A for the whole concentration range. For temperatures above 1200 0 C the calculated intermolecular coordination number shows that the intermolecular interaction increases. (BHO)

  13. Residual stress in sprayed Ni+5%Al coatings determined by neutron diffraction

    CERN Document Server

    Matejicek, J; Gnaeupel-Herold, T; Prask, H J

    2002-01-01

    Coatings of nickel-based alloys are used in numerous high-performance applications. Their properties and lifetimes are influenced by factors such as residual stress. Neutron diffraction is a powerful tool for nondestructive residual stress determination. In this study, through-thickness residual stress profiles in Ni+5%Al coatings on steel substrates were determined. Two examples of significantly different spraying techniques - plasma spraying and cold spraying - are highlighted. Different stress-generation mechanisms are discussed with respect to process parameters and material properties. (orig.)

  14. Location of adsorbed species in NO-reduction catalysts by high resolution neutron powder diffraction

    International Nuclear Information System (INIS)

    Fowkes, A.J.; Rosseinsky, M.J.

    1999-01-01

    Complete text of publication follows. Catalysts containing copper ion exchanged into zeolites are attracting considerable attention due to their efficiency for both NO decomposition and the selective catalytic reduction of NO x in so-called lean-burn conditions in automotive exhausts. This presentation will describe the application of in-situ high resolution neutron powder diffraction to study active sites in a Cu-zeolite Y catalyst active for NO decomposition. The study under NO pressure reveals the location of two distinct copper sites for sorption. The influence of copper oxidation state on the structure of both the pristine and NO-loaded zeolites will be discussed. (author)

  15. Non-destructive studies of fuel pellets by neutron resonance absorption radiography and thermal neutron radiography

    Energy Technology Data Exchange (ETDEWEB)

    Tremsin, A.S., E-mail: ast@ssl.berkeley.edu [University of California, Berkeley, CA 94720 (United States); Vogel, S.C.; Mocko, M.; Bourke, M.A.M.; Yuan, V.; Nelson, R.O.; Brown, D.W. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Feller, W.B. [NOVA Scientific, Inc., 10 Picker Rd., Sturbridge, MA 01566 (United States)

    2013-09-15

    Many isotopes in nuclear materials exhibit strong peaks in neutron absorption cross sections in the epithermal energy range (1–1000 eV). These peaks (often referred to as resonances) occur at energies specific to particular isotopes, providing a means of isotope identification and concentration measurements. The high penetration of epithermal neutrons through most materials is very useful for studies where samples consist of heavy-Z elements opaque to X-rays and sometimes to thermal neutrons as well. The characterization of nuclear fuel elements in their cladding can benefit from the development of high resolution neutron resonance absorption imaging (NRAI), enabled by recently developed spatially-resolved neutron time-of-flight detectors. In this technique the neutron transmission of the sample is measured as a function of spatial location and of neutron energy. In the region of the spectra that borders the resonance energy for a particular isotope, the reduction in transmission can be used to acquire an image revealing the 2-dimensional distribution of that isotope within the sample. Provided that the energy of each transmitted neutron is measured by the neutron detector used and the irradiated sample possesses neutron absorption resonances, then isotope-specific location maps can be acquired simultaneously for several isotopes. This can be done even in the case where samples are opaque or have very similar transmission for thermal neutrons and X-rays or where only low concentrations of particular isotopes are present (<0.1 atom% in some cases). Ultimately, such radiographs of isotope location can be utilized to measure isotope concentration, and can even be combined to produce three-dimensional distributions using tomographic methods. In this paper we present the proof-of-principle of NRAI and transmission Bragg edge imaging performed at Flight Path 5 (FP5) at the LANSCE pulsed, moderated neutron source of Los Alamos National Laboratory. A set of urania mockup

  16. Thermal, epithermal and thermalized neutron attenuation properties of ilmenite-serpentine heat resistant concrete shield

    International Nuclear Information System (INIS)

    Kany, A.M.I.; El-Gohary, M.I.; Kamal, S.M.

    1994-01-01

    Experimental measurements were carried out to study the attenuation properties of low-energy neutrons transmitted through unheated and preheated barriers of heavy-weight, highly hydrated and heat-resistant concrete shields. The concrete shields under investigation have been prepared from naturally occurring ilmenite and serpentine Egyptian ores. A collimated beam obtained from an Am-Be source was used as a source of neutrons, while the measurements of total thermal, epithermal, and thermalized neutron fluxes were performed using a BF-3 detector, multichannel analyzer and Cd filter. Results show that the ilmenite-serpentine concrete proved to be a better thermal, epithermal and thermalized neutron attenuator than the ordinary concrete especially at a high temperature of concrete exposure. (Author)

  17. Transmission of Thermal Neutrons through Boral

    Energy Technology Data Exchange (ETDEWEB)

    Aakerhielm, F

    1960-06-15

    Transmission measurements have been performed using Maxwellian distributed neutrons from the R1 reactor perpendicularly incident upon a boral absorption plate. American, English, German, Swedish and Swiss samples have been investigated and the results are compared to calculated values. The influence of the absorber grain size is discussed.

  18. Transmission of Thermal Neutrons through Boral

    International Nuclear Information System (INIS)

    Aakerhielm, F.

    1960-06-01

    Transmission measurements have been performed using Maxwellian distributed neutrons from the R1 reactor perpendicularly incident upon a boral absorption plate. American, English, German, Swedish and Swiss samples have been investigated and the results are compared to calculated values. The influence of the absorber grain size is discussed

  19. Thermal neutron equivalent doses assessment around KFUPM neutron source storage area using NTDs

    Energy Technology Data Exchange (ETDEWEB)

    Abu-Jarad, F.; Fazal-ur-Rehman; Al-Haddad, M.N.; Al-Jarrallah, M.I.; Nassar, R

    2002-07-01

    Area passive neutron dosemeters based on nuclear track detectors (NTDs) have been used for 13 days to assess accumulated low doses of thermal neutrons around neutron source storage area of the King Fahd University of Petroleum and Minerals (KFUPM). Moreover, the aim of this study is to check the effectiveness of shielding of the storage area. NTDs were mounted with the boron converter on their surface as one compressed unit. The converter is a lithium tetraborate (Li{sub 2}B{sub 4}O{sub 7}) layer for thermal neutron detection via {sup 10}B(N,{alpha}){sup 7}Li and {sup 6}Li(n,{alpha}){sup 3}H nuclear reactions. The area passive dosemeters were installed on 26 different locations around the source storage area and adjacent rooms. The calibration factor for NTD-based area passive neutron dosemeters was found to be 8.3 alpha tracks.cm{sup -2}.{mu}Sv{sup -1} using active snoopy neutron dosemeters in the KFUPM neutron irradiation facility. The results show the variation of accumulated dose with locations around the storage area. The range of dose rates varied from as low as 40 nSv.h{sup -1} up to 11 {mu}Sv.h{sup -1}. The study indicates that the area passive neutron dosemeter was able to detect accumulated doses as low as 40 nSv.h{sup -1}, which could not be detected with the available active neutron dosemeters. The results of the study also indicate that an additional shielding is required to bring the dose rates down to background level. The present investigation suggests extending this study to find the contribution of doses from fast neutrons around the neutron source storage area using NTDs through proton recoil. The significance of this passive technique is that it is highly sensitive and does not require any electronics or power supplies, as is the case in active systems. (author)

  20. Thermal neutron calibration channel at LNMRI/IRD

    International Nuclear Information System (INIS)

    Astuto, A.; Salgado, A.P.; Lopes, R.T.; Leite, S.P.; Patrao, K.C.S.; Fonseca, E.S.; Pereira, W.W.

    2014-01-01

    The Brazilian Metrology Laboratory of Ionizing Radiations (LNMRI) standard thermal neutron flux facility was designed to provide uniform neutron fluence for calibration of small neutron detectors and individual dosemeters. This fluence is obtained by neutron moderation from four 241 Am-Be sources, each with 596 GBq, in a facility built with blocks of graphite/paraffin compound and high-purity carbon graphite. This study was carried out in two steps. In the first step, simulations using the MCNPX code on different geometric arrangements of moderator materials and neutron sources were performed. The quality of the resulting neutron fluence in terms of spectrum, cadmium ratio and gamma-neutron ratio was evaluated. In the second step, the system was assembled based on the results obtained on the simulations, and new measurements are being made. These measurements will validate the system, and other intercomparisons will ensure traceability to the International System of Units. The pile construction form using blocks allows distinct arrangements for new studies and possibilities of other LNMRI reference fields. The results can be predicted by the simulation used in this work. Different number of each type of blocks and sources can be used. The main difference observed between the final measurement and simulation results might be due to the difference in composition of paraffin blocks used in assembling the pile. In order to confirm the thermal neutron field and fluence rate in the central chamber (inside the channel) that will be used to irradiate small neutron detectors, it is necessary to use another quantification method such as the gold foils activation with measurement traceability. It will be performed in a future stage. (authors)

  1. System and plastic scintillator for discrimination of thermal neutron, fast neutron, and gamma radiation

    Science.gov (United States)

    Zaitseva, Natalia P.; Carman, M. Leslie; Faust, Michelle A.; Glenn, Andrew M.; Martinez, H. Paul; Pawelczak, Iwona A.; Payne, Stephen A.

    2017-05-16

    A scintillator material according to one embodiment includes a polymer matrix; a primary dye in the polymer matrix, the primary dye being a fluorescent dye, the primary dye being present in an amount of 3 wt % or more; and at least one component in the polymer matrix, the component being selected from a group consisting of B, Li, Gd, a B-containing compound, a Li-containing compound and a Gd-containing compound, wherein the scintillator material exhibits an optical response signature for thermal neutrons that is different than an optical response signature for fast neutrons and gamma rays. A system according to one embodiment includes a scintillator material as disclosed herein and a photodetector for detecting the response of the material to fast neutron, thermal neutron and gamma ray irradiation.

  2. VHTR core modeling: coupling between neutronic and thermal-hydraulics

    International Nuclear Information System (INIS)

    Limaiem, I.; Damian, F.; Raepsaet, X.; Studer, E.

    2005-01-01

    Following the present interest in the next generation nuclear power plan (NGNP), Cea is deploying special effort to develop new models and qualify its research tools for this next generation reactors core. In this framework, the Very High Temperature Reactor concept (VHTR) has an increasing place in the actual research program. In such type of core, a strong interaction exists between neutronic and thermal-hydraulics. Consequently, the global core modelling requires accounting for the temperature feedback in the neutronic models. The purpose of this paper is to present the new neutronic and thermal-hydraulics coupling model dedicated to the High Temperature Reactors (HTR). The coupling model integrates a new version of the neutronic scheme calculation developed in collaboration between Cea and Framatome-ANP. The neutronic calculations are performed using a specific calculation processes based on the APOLLO2 transport code and CRONOS2 diffusion code which are part of the French reactor physics code system SAPHYR. The thermal-hydraulics model is characterised by an equivalent porous media and 1-D fluid/3-D thermal model implemented in the CAST3M/ARCTURUS code. The porous media approach involves the definition of both homogenous and heterogeneous models to ensure a correct temperature feedback. This study highlights the sensitivity of the coupling system's parameters (radial/axial meshing and data exchange strategy between neutronic and thermal-hydraulics code). The parameters sensitivity study leads to the definition of an optimal coupling system specification for the VHTR. Besides, this work presents the first physical analysis of the VHTR core in steady-state condition. The analysis gives information about the 3-D power peaking and the temperature coefficient. Indeed, it covers different core configurations with different helium distribution in the core bypass. (authors)

  3. Parameters measurement for the thermal neutron beam in the thermal column hole of Xi’an pulse reactor

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The distribution of the neutron spectra in the thermal column hole of Xi’an pulse reactor was measured with the time-of-flight method.Compared with the thermal Maxwellian theory neutron spectra,the thermal neutron spectra measured is a little softer,and the average neutron energy of the experimental spectra is about 0.042±0.01 eV.The thermal neutron fluence rate at the front end of thermal column hole,measured with gold foil activation techniques,is about 1.18×105 cm-2 s-1.The standard uncertainty of the measured thermal neutron fluence is about 3%.The spectra-averaged cross section of 197Au(n,γ) determined by the experimental thermal neutron spectra is(92.8±0.93) ×10-24 cm2.

  4. Experimental determination of anomalous scattering lengths of samarium for thermal neutrons

    International Nuclear Information System (INIS)

    Engel, D.W.; Koetzle, T.F.

    1981-01-01

    Anomalous scattering lengths of natural Sm for thermal neutrons with wavelengths between 0.827 and 1.300 A have been determined using a single crysrtal of a Sm-complex of known structure. 140 selected reflections were measured at each wavelength and b 0 + b' and b'' refined in each case. The values obtained are in good agreement with theoretical values obtained from a Breit-Wigner calculation using tabulated resonance parameters for 149 Sm. A value of b 0 = 4.3 +- 0.2 fm is deduced from the diffraction experiment

  5. Microscopic cross-section measurements by thermal neutron activation

    International Nuclear Information System (INIS)

    Avila L, J.

    1987-08-01

    Microscopic cross sections measured by thermal neutron activation using RP-0 reactor at the Peruvian Nuclear Energy Institute. The method consists in measuring microscopic cross section ratios through activated samples, requiring being corrected in thermal and epithermal energetic range by Westcott formalism. Furthermore, the comptage ratios measured for each photopeak to its decay fraction should be normalized from interrelation between both processes above, activation microscopic cross sections are obtained

  6. Thermal hydraulic and neutronic interaction in the rotating bed reactor

    International Nuclear Information System (INIS)

    Lee, C.C.

    1986-01-01

    Power transient characteristics in a rotating fluidized bed reactor (RBR) are investigated theoretically. A propellant flow perturbation is assumed to occur in an initially equilibrium state of the core. Transfer functions representing quasi-one-dimensional mutual feedback between thermal hydraulics and neutronics are developed and analyzed in the frequency domain. Neutronic responses are determined by Fermi-age theory for slowing down of fast neutrons and diffusion theory for thermal neutron distribution. Neutron leakage through the exhaust nozzle is accounted for by applying diffuse view factors similar to those applied in radiative heat transfer. The bed expansion behavior is described by a kinematic wave equation derived from the continuity of the gas phase. The drift flux approach is used to determine the yield fractions in the equilibrium bed. Thermal responses of fuel are evaluated by dividing it into several volume-averaged zones to better account for the transient effects over single zone models. Sample calculations are undertaken for the various operation conditions and design parameters of the RBR based on 250 MW/sub t/, 1000 MW/sub t/, and 5000 MW/sub t/ power reactors. The results show that power transients are dependent on the parametric changes of optical thickness and view factors

  7. Phase separation and magnetic ordering studied by high resolution neutron diffraction

    International Nuclear Information System (INIS)

    Caspi, E.N.; Melamud, M.; Pinto, H.; Shaked, H.; Chmaissem, O.; Jorgensen, J.D.; Short, S.

    1999-01-01

    Complete text of publication follows. In a previous work on the (U 1-x Nd x )Co 2 Ge 2 system, two magnetic transitions were observed in the temperature dependencies of the magnetic susceptibility and in the intensity of the magnetic reflections in neutron diffraction [1]. Because of insufficient resolution, it was not clear whether this is due to clustering or phase separation. In both cases the U-rich regions are expected to order magnetically at higher temperature than the U-poor ones, resulting in two magnetic transitions. In order to resolve this question a temperature dependent TOF neutron diffraction of the x = 0.25 compound has been performed on the SEPD at Argonne's IPNS [2]. The temperature dependent diffractograms were refined by the Rietveld method. It was found that the compound separates into two phases: x = 0.4 (55 wt%) and x = 0.1 (45 wt%). The temperature dependence of the magnetic moment was obtained for each phase, with the transition temperatures: T N (x=0.4) = 130 K, and T N (x=0.1) = 165 K. (author) [1] E. Caspi et al., Phys. Rev. B, 57 (198) 449.; [2] J.D. Jorgensen et al., J. Appl. Cryst. 22 (1989) 321

  8. The chemical reactivity and structure of collagen studied by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Wess, T.J.; Wess, L.; Miller, A. [Univ. of Stirling (United Kingdom)

    1994-12-31

    The chemical reactivity of collagen can be studied using neutron diffraction (a non-destructive technique), for certain reaction types. Collagen contains a number of lysine and hydroxylysine side chains that can react with aldehydes and ketones, or these side chains can themselves be converted to aldehydes by lysyl oxidase. The reactivity of these groups not only has an important role in the maintenance of mechanical strength in collagen fibrils, but can also manifest pathologically in the cases of aging, diabetes (reactivity with a variety of sugars) and alcoholism (reactivity with acetaldehyde). The reactivity of reducing groups with collagen can be studied by neutron diffraction, since the crosslink formed in the adduction process is initially of a Schiff base or keto-imine nature. The nature of this crosslink allows it to be deuterated, and the position of this relatively heavy scattering atom can be used in a process of phase determination by multiple isomorphous replacement. This process was used to study the following: the position of natural crosslinks in collagen; the position of adducts in tendon from diabetic rats in vivo and the in vitro position of acetaidehyde adducts in tendon.

  9. Neutron-diffraction measurement of residual stresses in Al-Cu cold-cut welding

    Science.gov (United States)

    Fiori, F.; Marcantoni, M.

    Usually, when it is necessary to join different materials with a large difference in their melting points, welding should be avoided. To overcome this problem we designed and built a device to obtain cold-cut welding, which is able to strongly decrease oxidation problems of the surfaces to be welded. Thanks to this device it is possible to achieve good joining between different pairs of materials (Al-Ti, Cu-Al, Cu-Al alloys) without reaching the material melting point. The mechanical and microstructural characterisation of the joining and the validation of its quality were obtained using several experimental methods. In particular, in this work neutron-diffraction experiments for the evaluation of residual stresses in Cu-Al junctions are described, carried out at the G5.2 diffractometer of LLB, Saclay. Neutron-diffraction results are presented and related to other experimental tests such as microstructural characterisation (through optical and scanning electron microscopy) and mechanical characterisation (tensile-strength tests) of the welded interface.

  10. Diffraction des neutrons : principe, dispositifs expérimentaux et applications

    Science.gov (United States)

    Muller, C.

    2003-02-01

    La diffraction de neutrons, sur monocristal ou sur échantillon polycristallin (ou poudre), est une technique très largement utilisée, en science des matériaux comme en biologie, lorsque l'on souhaite déterminer la structure cristalline d'un composé ou d'une molécule. Toutefois, le degré de précision de la détermination structurale est très corrélé au choix de l'instrument utilisé. Il s'en suit que la question “comment choisir l'instrument le mieux adapté au composé et à la problématique ?" apparaît comme fondamentale. L'objectif de ce cours est de tenter de répondre à cette question en décrivant brièvement les caractéristiques instrumentales de différents diffractomètres, en exposant les avantages spécifiques des expériences de diffraction de neutrons et en donnant quelques exemples d'application.

  11. In situ observation and neutron diffraction of NiTi powder sintering

    International Nuclear Information System (INIS)

    Chen, Gang; Liss, Klaus-Dieter; Cao, Peng

    2014-01-01

    This study investigated NiTi powder sintering behaviour from elemental powder mixtures of Ni/Ti and Ni/TiH 2 using in situ neutron diffraction and in situ scanning electron microscopy. The sintered porous alloys have open porosities ranging from 2.7% to 36.0%. In comparison to the Ni/Ti compact, dehydrogenation occurring in the Ni/TiH 2 compact leads to less densification yet higher chemical homogenization only after high-temperature sintering. For the first time, direct evidence of the eutectoid phase transformation of NiTi at 620 °C is reported by in situ neutron diffraction. A comparative study of cyclic stress–strain behaviours of the porous NiTi alloys made from Ni/Ti and Ni/TiH 2 compacts indicate that the samples sintered from the Ni/TiH 2 compact exhibited a much higher porosity, larger pore size, lower fracture strength, lower close-to-overall porosity ratio and lower Young’s modulus. Instead of enhanced densification by the use of TiH 2 as reported in the literature, this study shows an adverse effect of TiH 2 on powder densification in NiTi

  12. Neutron diffraction study of single crystalline ErCo10Mo2

    International Nuclear Information System (INIS)

    Janssen, Y.; De Boer, F.R.; Brueck, E.; Tegus, O.; Ma, L.; Buschow, K.H.J.; Reehuis, M.

    1999-01-01

    Complete text of publication follows. The ferrimagnetic intermetallic compound ErCo 10 Mo 2 (Tc = 600 K) crystallizes in the tetragonal ThMn 12 -type structure (space group 14/mmm). The Co and Mo atoms may share three crystallographic sites (8f, 8i and 8j). Earlier neutron powder diffraction experiments show that Mo has a strong preference for the 8i-site and that the magnetic ordering at low temperature is planar. Furthermore ErCo 10 Mo 2 has been reported to show one [2] or more [3] spin-reorientation transitions from planar to axial magnetic ordering. Recently we succeeded in growing a single-crystalline sample of ErCo 10 Mo 2 . Magnetic measurements in 1T show one spin-reorientation transition at about 135 K. Neutron diffraction experiments were performed to investigate a possible link between the magnetic properties and the site occupation by Mo. Our results show that our sample has the Mo atoms exclusively occupying half the 8i-sites. There is no evidence for a crystallographic superstructure. Furthermore, below 150 K some reflections strongly increase due to the growing Er magnetic moment. (author)

  13. Neutron-diffraction studies of the nuclear magnetic phase diagram of copper

    DEFF Research Database (Denmark)

    Annila, A.J.; Clausen, Kurt Nørgaard; Oja, A.S.

    1992-01-01

    We have studied the spontaneous antiferromagnetic (AF) order in the nuclear spin system of copper by use of neutron-diffraction experiments at nanokelvin temperatures. Copper is an ideal model system as a nearest-neighbor-dominated spin-3/2 fcc antiferromagnet. The phase diagram has been investig......We have studied the spontaneous antiferromagnetic (AF) order in the nuclear spin system of copper by use of neutron-diffraction experiments at nanokelvin temperatures. Copper is an ideal model system as a nearest-neighbor-dominated spin-3/2 fcc antiferromagnet. The phase diagram has been...... investigated by measuring the magnetic-field dependence of the (100) reflection, characteristic of a type-I AF structure, and of a Bragg peak at (0 2/3 2/3). The results suggest the presence of high-field (100) phases at 0.12 less-than-or-equal-to B less-than-or-equal-to B(c) almost-equal-to 0.26 mT, for B...... compared with results of earlier susceptibility measurements in order to identify the translational periods of the three previously found antiferromagnetic phases for B parallel-to [100]. Recent theoretical work has yielded results in agreement with our experimental data....

  14. The chemical reactivity and structure of collagen studied by neutron diffraction

    International Nuclear Information System (INIS)

    Wess, T.J.; Wess, L.; Miller, A.

    1994-01-01

    The chemical reactivity of collagen can be studied using neutron diffraction (a non-destructive technique), for certain reaction types. Collagen contains a number of lysine and hydroxylysine side chains that can react with aldehydes and ketones, or these side chains can themselves be converted to aldehydes by lysyl oxidase. The reactivity of these groups not only has an important role in the maintenance of mechanical strength in collagen fibrils, but can also manifest pathologically in the cases of aging, diabetes (reactivity with a variety of sugars) and alcoholism (reactivity with acetaldehyde). The reactivity of reducing groups with collagen can be studied by neutron diffraction, since the crosslink formed in the adduction process is initially of a Schiff base or keto-imine nature. The nature of this crosslink allows it to be deuterated, and the position of this relatively heavy scattering atom can be used in a process of phase determination by multiple isomorphous replacement. This process was used to study the following: the position of natural crosslinks in collagen; the position of adducts in tendon from diabetic rats in vivo and the in vitro position of acetaidehyde adducts in tendon

  15. Structure, magnetic properties, polarized neutron diffraction, and theoretical study of a copper(II) cubane.

    Science.gov (United States)

    Aronica, Christophe; Chumakov, Yurii; Jeanneau, Erwann; Luneau, Dominique; Neugebauer, Petr; Barra, Anne-Laure; Gillon, Béatrice; Goujon, Antoine; Cousson, Alain; Tercero, Javier; Ruiz, Eliseo

    2008-01-01

    The paper reports the synthesis, X-ray and neutron diffraction crystal structures, magnetic properties, high field-high frequency EPR (HF-EPR), spin density and theoretical description of the tetranuclear CuII complex [Cu4L4] with cubane-like structure (LH2=1,1,1-trifluoro-7-hydroxy-4-methyl-5-aza-hept-3-en-2-one). The simulation of the magnetic behavior gives a predominant ferromagnetic interaction J1 (+30.5 cm(-1)) and a weak antiferromagnetic interaction J2 (-5.5 cm(-1)), which correspond to short and long Cu-Cu distances, respectively, as evidence from the crystal structure [see formulate in text]. It is in agreement with DFT calculations and with the saturation magnetization value of an S=2 ground spin state. HF-EPR measurements at low temperatures (5 to 30 K) provide evidence for a negative axial zero-field splitting parameter D (-0.25+/-0.01 cm(-1)) plus a small rhombic term E (0.025+/-0.001 cm(-1), E/D = 0.1). The experimental spin distribution from polarized neutron diffraction is mainly located in the basal plane of the CuII ion with a distortion of yz-type for one CuII ion. Delocalization on the ligand (L) is observed but to a smaller extent than expected from DFT calculations.

  16. Determination of the Magnetic Structure of Complex anti-Perovskite Fluorides by Neutron Diffraction

    Science.gov (United States)

    Felder, Justin; Yeon, Jeongho; Zur Loye, Hans-Conrad

    An unusual family of anti-perovskite fluorides consisting of complex ions as the A, B, and X building units has been synthesized as single crystals. This family of anti-perovskites provides a unique framework to probe the magnetic properties of transition metals. Presented here is the Fe endmember of the family: [Cu(H2O)4]3[FeF6]2. The iron member exhibits complex magnetic behavior at low temperatures, which has been probed by magnetometry and neutron diffraction experiments. Presented here are the results from the anisotropic magnetometry study as well as the magnetic spin structure as determined by neutron diffraction experiments. The materials presented here represent an interesting class of perovskites that are as-yet unexplored. Given the wide range of properties possible in perovskites and related structures, it is reasonable to expect that further exploration of these materials will reveal many interesting attributes; both chemical and physical. United States Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, Award DE-SC0008664.

  17. Specimen environments in thermal neutron scattering experiments

    International Nuclear Information System (INIS)

    Cebula, D.J.

    1980-11-01

    This report is an attempt to collect into one place outline information concerning the techniques used and basic design of sample environment apparatus employed in neutron scattering experiments. Preliminary recommendations for the specimen environment programme of the SNS are presented. The general conclusion reached is that effort should be devoted towards improving reliability and efficiency of operation of specimen environment apparatus and developing systems which are robust and easy to use, rather than achieving performance at the limits of technology. (author)

  18. Physics with Ultracold and Thermal Neutron Beams

    International Nuclear Information System (INIS)

    None

    2004-01-01

    The final report is broken into 5 segments, reflecting research conclusions reached during specific time periods: 1991-1997, 1997-1999, 1999-2000, 2000-2001, and 2001-2002. The first part of the work reported was carried out at the 2 Mw research reactor of the Rhode Island Nuclaer Science Center (RJNSC). Chosen for study was the slow phase separation in mixtures of oil and water in the presence of a surfactant, and the structural features of an oil layer during the slow build-up from the gas phase. The results of these measurements, as well as studies of the capillary wave properties of oil/surfactant/water interfaces are described. The second part of the work was performed at the neutron reflection facilities of the Intennse Pulsed Neutron Source at Argonne and of the NBSR reactor at NIST. At Argonne, the uniaxial magnetic order of an Fe/CR superlattice was investigated, while the experiments at NIST studied the swelling behavior of ordered thin films of diblock copolymers when they were exposed to solvent vapors. The third part of the work was concerned with the storage properties of ultracold neturons in a trap. New experiments on spectral evolution during storage, using the UCN source of the Institut Laue-Langevin were able to be run. Subsequent periods focussed on the ultracold neutrons work, spin valve multilayer systems, and pseudo-partial wetting

  19. 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

  20. Need for nuclear data for thermal neutron reactors

    International Nuclear Information System (INIS)

    Bouchard, J.; Golinelli, C.; Tellier, H.

    1983-01-01

    The need for nuclear data for thermal neutron reactors is conditioned by the persisting lack of agreement between the calculation and measurement of certain parameters, by the benefit that can be drawn from reduction of the marginal areas and by envisaged modifications. Three particular fields are delineated. Reduction of the deviation in temperature coefficients by modification of the shape of the effective capture cross sections of uranium-238 and -235 in the thermal range. The increase in precision of kinetic measurements by a better knowledge of data connected to slowed-down neutrons. Improvement in predicting the neutron activity of the fuels used in measuring the effective capture cross sections of plutonium-242 and americium-243. (Auth.)

  1. Measurement of the diffusion length of thermal neutrons inside graphite

    International Nuclear Information System (INIS)

    Ertaud, A.; Beauge, R.; Fauquez, H.; De Laboulay, H.; Mercier, C.; Vautrey, L.

    1948-11-01

    The diffusion length of thermal neutrons inside a given industrial graphite is determined by measuring the neutron density inside a parallelepipedal piling up of graphite bricks (2.10 x 2.10 x 2.442 m). A 3.8 curies (Ra α → Be) source is placed inside the parallelepipedal block of graphite and thin manganese detectors are used. Corrections are added to the unweighted measurements to take into account the effects of the damping of supra-thermal neutrons in the measurement area. These corrections are experimentally deduced from the differential measurements made with a cadmium screen interposed between the source and the first plane of measurement. An error analysis completes the report. The diffusion length obtained is: L = 45.7 cm ± 0.3. The average density of the graphite used is 1.76 and the average apparent density of the piling up is 1.71. (J.S.)

  2. High temperature ductility of austenitic alloys exposed to thermal neutrons

    International Nuclear Information System (INIS)

    Watanabe, K.; Kondo, T.; Ogawa, Y.

    1982-01-01

    Loss of high temperature ductility due to thermal neutron irradiation was examined by slow strain rate test in vacuum up to 1000 0 C. The results on two heats of Hastelloy alloy X with different boron contents were analyzed with respect to the influence of the temperatures of irradiation and tensile tests, neutron fluence and the associated helium production due to nuclear transmutation reaction. The loss of ductility was enhanced by increasing either temperature or neutron fluence. Simple extrapolations yielded the estimated threshold fluence and the end-of-life ductility values at 900 and 1000 0 C in case where the materials were used in near-core regions of VHTR. The observed relationship between Ni content and the ductility loss has suggested a potential utilization of Fe-based alloys for seathing of the neutron absorber materials

  3. Equipment for thermal neutron flux measurements in reactor R2

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, E; Nilsson, T; Claeson, S

    1960-04-15

    For most of the thermal neutron flux measurements in reactor R2 cobalt wires will be used. The loading and removal of these wires from the reactor core will be performed by means of a long aluminium tube and electromagnets. After irradiation the wires will be scanned in a semi-automatic device.

  4. Parallel diffusion length on thermal neutrons in rod type lattices

    International Nuclear Information System (INIS)

    Ahmed, T.; Siddiqui, S.A.M.M.; Khan, A.M.

    1981-11-01

    Calculation of diffusion lengths of thermal neutrons in lead-water and aluminum water lattices in direction parallel to the rods are performed using one group diffusion equation together with Shevelev transport correction. The formalism is then applied to two practical cases, the Kawasaki (Hitachi) and the Douglas point (Candu) reactor lattices. Our results are in good agreement with the observed values. (author)

  5. Response of neutron-irradiated RPV steels to thermal annealing

    International Nuclear Information System (INIS)

    Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K.

    1997-01-01

    One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPVs) is to thermally anneal them to restore the fracture toughness properties that have been degraded by neutron irradiation. This paper summarizes experimental results of work performed at the Oak Ridge National Laboratory (ORNL) to study the annealing response of several irradiated RPV steels

  6. A two-medium thermal neutron spectrum programme

    International Nuclear Information System (INIS)

    Bindon, D.C.

    1960-07-01

    A computer programme is described for computing the thermal neutron spectra and effective cross-sections in a reactor system of two media by the method of H. Takahashi. The programme has been prepared and tested for use with the Ferranti Mercury computer. (author)

  7. Quantitative phase analysis of alumina/calcium-hexaluminate composites using neutron diffraction data and the Rietveld method

    International Nuclear Information System (INIS)

    Asmi, D.; Low, I.M.; O'Connor, B.H.; Kennedy, S.J.

    2000-01-01

    Full text: The Al 2 O 3 -CaO system is the basis of an important class of high-temperature refractories in the steel industry. It contains a number of stable intermediate compounds which include C 3 A, C 12 A 7 , CA, CA 2 , and CA 6 . These calcium aluminates are also important constituents of high alumina cement and have been used to produce high-strength and high-toughness ceramic-polymer composite materials. More recently, alumina composites containing 30 wt% CA 6 platelets have been developed by An et al which show characteristics of self-reinforcement and enhanced toughening through crack-bridging. In this paper, we describe the use of high-temperature neutron diffraction to monitor the in-situ phase formation and abundances of calcium aluminates (CA, CA 2 , and CA 6 ) in alumina composites containing 5-50 wt % CA 6 .at temperatures in the range 1000 - 1600 deg C. These composites were produced using reaction sintering of alumina and calcium oxide. For comparison purposes, control samples of pure α-alumina and CA 6 were also produced. Determination of relative phase abundances in these materials has been performed using the standardless Rietveld refinement method. Results show that the relative phase abundance of calcium aluminates in the composites increased with temperature and in proportion with the amount of calcium oxide present. The formation temperatures of CA, CA 2 , and CA 6 have been observed to occur at 1000 deg , 1200 deg, and ∼1350 deg C respectively, which agree well with results obtained from x-ray diffraction, synchrotron radiation diffraction and differential thermal analysis

  8. Thermal neutron self-shielding correction factors for large sample instrumental neutron activation analysis using the MCNP code

    International Nuclear Information System (INIS)

    Tzika, F.; Stamatelatos, I.E.

    2004-01-01

    Thermal neutron self-shielding within large samples was studied using the Monte Carlo neutron transport code MCNP. The code enabled a three-dimensional modeling of the actual source and geometry configuration including reactor core, graphite pile and sample. Neutron flux self-shielding correction factors derived for a set of materials of interest for large sample neutron activation analysis are presented and evaluated. Simulations were experimentally verified by measurements performed using activation foils. The results of this study can be applied in order to determine neutron self-shielding factors of unknown samples from the thermal neutron fluxes measured at the surface of the sample

  9. A neutron diffraction study of pyridinium-1-dicyanomethylide, C8D5N3, at 294 K and 118 K

    International Nuclear Information System (INIS)

    Devos, L.; Baert, F.; Fouret, R.; Thomas, M.

    1980-01-01

    A neutron diffraction study of perdeuterated pyridium-1-dicyanomethylide has been carried out at room temperature and at 118 K at the high-flux beam reactor of the Institut Laue-Langevin. Low temperature was obtained with a cryostat based on the Joule-Thomson expansion of gaseous helium, with a maximum long-term variation of +-1 K. The crystals are monoclinic, space group P2 1 /m. The data refinements, including extinction parameters, gave final Rsub(w)(F 2 ) values of 0.038 (RT, 552 independent reflections) and 0.028 (118 K, 1869 independent reflections). A TLS thermal analysis indicated rigid-body behaviour of the non-deuterium atoms. The non-planarity of the molecule was confirmed. The bond distances were corrected for thermal motion and their e.s.d.'s ranged from 0.0012 to 0.0030 A (RT) and from 0.0003 to 0.0008 A (118 K). (Auth.)

  10. Structural refinement and extraction of hydrogen atomic positions in polyoxymethylene crystal based on the first successful measurements of 2-dimensional high-energy synchrotron X-ray diffraction and wide-angle neutron diffraction patterns of hydrogenated and deuterated species

    International Nuclear Information System (INIS)

    Tashiro, Kohji; Hanesaka, Makoto; Ohhara, Takashi; Kurihara, Kazuo; Tamada, Taro; Kuroki, Ryota; Fujiwara, Satoru; Ozeki, Tomoji; Kitano, Toshiaki; Nishu, Takashi; Tanaka, Ichiro; Niimura, Nobuo

    2007-01-01

    2-Dimensional X-ray and neutron diffraction patterns have been successfully measured for deuterated and hydrogenated polyoxymethylene (POM) samples obtained by γ-ray induced solid-state polymerization reaction. More than 700 reflections were collected from the X-ray diffraction data at -150degC by utilizing a high-energy synchrotron X-ray beam at SPring-8, Japan, from which the crystal structure of POM has been refined thoroughly including the extraction of hydrogen atomic positions at clearly seen in the difference Fourier synthesis map. As the first trial the nonuniform (9/5) helical model was analyzed with the reliability factor (R factor) 6.9%. The structural analysis was made also using the X-ray reflections of about 400 observed at room temperature (R 8.8%), and the thermal parameters of constituent atoms were compared between the low and high temperatures to discuss the librational thermal motion of the chains. The 2-dimensional neutron diffraction data, collected for the deuterated and hydrogenated POM samples using an imaging plate system specifically built-up for neutron scattering experiment, have allowed us to pick up the D and H atomic positions clearly in the Fourier synthesis maps. Another possible model, (29/16) helix, which was proposed by several researches, has been also investigated on the basis of the X-ray diffraction data at -150degC. The direct method succeeded in extracting this (29/16) model straightforwardly. The R factor was 8.6%, essentially the same as that of (9/5) helical model. This means that the comparison of the diffraction intensity between the data collected from the full-rotation X-ray diffraction pattern and the intensity calculated for both the (9/5) and (29/16) models cannot be used for the unique determination of the superiority of the model, (9/5) or (29/16) helix. However, we have found the existence of 001 and 002 reflections which give the longer repeating period 55.7 A. Besides there observed a series of meridional

  11. Determination of crystalline texture in aluminium - uranium alloys by neutron diffraction

    International Nuclear Information System (INIS)

    Azevedo, A.M.V. de.

    1978-01-01

    Textures of hot-rolled aluminum-uranium alloys and of aluminum were determined by neutron diffraction. Sheets of alloys containing 8.0, 21.5 and 23.7 wt pct U, as well as pure aluminum, were obtained in a stepped rolling process, 15% reduction each step, 75% total reduction. During the rolling the temperature was 600 0 C. Alloys with low uranium contents are two phase systems in which an intermetallic compound UAl 4 , orthorhombic, is dispersed in a pure aluminum matrix. The addition of a few percent of Si in such alloys leads to the formation of UAl 3 , simple cubic, instead of UAl 4 . The Al -- 23.7 wt pct U alloy was prepared with 2,2 wt pct of Si. The results indicate that the texture of the matrix is more dependent on the uranium concentration than on the texture of the intermetallic phases. An improvement in the technique applied to texture measurements by using a sample fully bathed in the neutron beam is also presented. The method takes advantage of the low neutron absorption of the studied materials as well as of the neglibible variation in the multiple scattering which occurs in a conveniently shaped sample having a weakly developed texture. (Author) [pt

  12. 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.

  13. Beryllium, zinc and lead single crystals as a thermal neutron monochromators

    Science.gov (United States)

    Adib, M.; Habib, N.; Bashter, I. I.; Morcos, H. N.; El-Mesiry, M. S.; Mansy, M. S.

    2015-03-01

    The monochromatic features of Be, Zn and Pb single crystals are discussed in terms of orientation, mosaic spread, and thickness within the wavelength band from 0.04 up to 0.5 nm. A computer program MONO written in "FORTRAN-77", has been adapted to carry out the required calculations. Calculations show that a 5 mm thick of beryllium (HCP structure) single crystal cut along its (0 0 2) plane having 0.6° FWHM are the optimum parameters when it is used as a monochromator with high reflected neutron intensity from a thermal neutron flux. Furthermore, at wavelengths shorter than 0.16 nm it is free from the accompanying higher order ones. Zinc (HCP structure) has the same parameters, with intensity much less than the latter. The same features are seen with lead (FCC structure) cut along its (3 1 1) plane with less reflectivity than the former. However, Pb (3 1 1) is more preferable than others at neutron wavelengths ⩽ 0.1 nm, since the glancing angle (θ ∼ 20°) is more suitable to carry out diffraction experiments. For a cold neutron flux, the first-order neutrons reflected from beryllium is free from the higher orders up to 0.36 nm. While for Zn single crystal is up to 0.5 nm.

  14. Application of neutron diffraction in characterization of texture evolution during high-temperature creep in magnesium alloys

    International Nuclear Information System (INIS)

    Sediako, A.; Shook, S.; Vogel, S.; Sediako, D.

    2010-01-01

    A good combination of room-temperature and elevated temperature strength and ductility, good salt-spray corrosion resistance and excellent diecastability are frequently among the main considerations in development of a new magnesium alloy for automotive industry. Unfortunately, there has been much lesser effort in development of wrought-stock alloys for high temperature applications. Extrudability and high temperature performance of wrought material become important factors in an effort to develop new wrought alloys and processing technologies. This paper shows some results received in creep testing and studies of in-creep texture evolution for several wrought magnesium alloys developed for use in elevated- temperature applications. Along with others 'traditional' characterization techniques of metals' performance in high- temperature creep, neutron diffraction was employed in this study to analyze evolution of crystallographic texture during creep deformation. The paper compares two methods of texture analysis in neutron diffraction studies: based on monochromatic (reactor-source) beam and white neutron beam (time-of-flight method, synchrotron). The time-of-flight (TOF) spectrometer illuminates the sample with a non-filtered beam of neutrons and captures the readings with an encircled detector array. This provides a very fast and detailed picture of the crystallographic texture for the bulk of the sample. As the white beam retains all neutron wavelengths, it takes much less time to collect statistically-valid dataset for the diffraction pattern. On the other hand, the monochromatic beam setup includes a monochromatic crystal that filters out a specific wavelength. The diffracted beam is then captured by a much simpler neutron detector. This setup is more flexible, allowing for choosing various wavelengths (depending on the sample material) but obviously requiring more time for statistically viable data collection. These studies were performed using E3 neutron

  15. Effect of external stress on deuteride (hydride) precipitation in Zircaloy-4 using in situ neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jun-li [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); An, Ke; Stoica, Alexandru D. [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Heuser, Brent J., E-mail: bheuser@illinois.edu [Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

    2017-04-15

    In situ neutron diffraction is utilized to study the deuteride (hydride) precipitation behavior in a cold-worked stress-relieved (CWSR) Zircaloy-4 material upon cooling from 420 °C to room temperature with a 78 MPa external stress applied along the rolling direction (RD) of the material. Two banks detector capture the diffraction signal from two principal directions of the specimen, the normal direction (ND) and the rolling direction (RD). The evolution of deuterium concentration in zirconium solid solution along the two specimen directions is measured by studying the δ-(220) peak intensity, applying the Rietveld refinement method to the diffraction data and using the measured zirconium c-axis lattice distortion. The deuterium concentration is observed to be higher for zirconium grains in the ND than the RD. The terminal solid solubility of precipitation (TSSp) for deuterium in the solution is then described using the Arrhenius equation. It is observed that the applied stress reduces the energy term Q in the Arrhenius equation when compared with the unstressed Q values from the work of others. A model by Puls is applied to study the effect of stress on deuterium solubility, with polycrystalline hydride precipitation strain calculated using the Kearns factor representative of the studied material. The experimental result does not agree with the model prediction of Puls.

  16. A comparison of texture results obtained using precession electron diffraction and neutron diffraction methods at diminishing length scales in ordered bimetallic nanolamellar composites

    International Nuclear Information System (INIS)

    Carpenter, J.S.; Liu, X.; Darbal, A.; Nuhfer, N.T.; McCabe, R.J.; Vogel, S.C.; LeDonne, J.E.; Rollett, A.D.; Barmak, K.; Beyerlein, I.J.; Mara, N.A.

    2012-01-01

    Precession electron diffraction (PED) is used to acquire orientation information in Cu–Nb nanolamellar composites fabricated by accumulative roll bonding (ARB). The resulting maps quantify the grain size, shape, orientation distributions and interface planes in the vicinity of nanometer-thick deformation twins. The PED-based texture results compare favorably with bulk textures provided by neutron diffraction measurements, indicating uniformity in the ARB Cu–Nb texture. Additionally, {1 1 2} Cu ||{1 1 2} Nb interfaces are present, suggesting that ARB techniques can lead to stable interfaces with a special crystallography.

  17. Detection of land mines using fast and thermal neutron analysis

    International Nuclear Information System (INIS)

    Bach, P.

    1998-01-01

    The detection of land mines is made possible by using nuclear sensor based on neutron interrogation. Neutron interrogation allows to detect the sensitive elements (C, H, O, N) of the explosives in land mines or in unexploded shells: the evaluation of characteristic ratio N/O and C/O in a volume element gives a signature of high explosives. Fast neutron interrogation has been qualified in our laboratories as a powerful close distance method for identifying the presence of a mine or explosive. This method could be implemented together with a multisensor detection system - for instance IR or microwave - to reduce the false alarm rate by addressing the suspected area. Principle of operation is based on the measurement of gamma rays induced by neutron interaction with irradiated nuclei from the soil and from a possible mine. Specific energy of these gamma rays allows to recognise the elements at the origin of neutron interaction. Several detection methods can be used, depending on nuclei to be identified. Analysis of physical data, computations by simulation codes, and experimentations performed in our laboratory have shown the interest of Fast Neutron Analysis (FNA) combined with Thermal Neutron Analysis (TNA) techniques, especially for detection of nitrogen 14 N, carbon 12 C and oxygen 16 O. The FNA technique can be implemented using a 14 MeV sealed neutron tube, and a set of detectors. The mines detection has been demonstrated from our investigations, using a low power neutron generator working in the 10 8 n/s range, which is reasonable when considering safety rules. A fieldable demonstrator would be made with a detection head including tube and detectors, and with remote electronics, power supplies and computer installed in a vehicle. (author)

  18. Boron thermal/epithermal neutron capture therapy

    International Nuclear Information System (INIS)

    Fairchild, R.G.

    1982-01-01

    The development of various particle beams for radiotherapy represents an attempt to improve dose distribution, and to provide high LET radiations which are less sensitive to ambient physical and radiobiological factors such as oxygen tension, cell cycle, and dose rate. In general, a compromise is necessary as effective RBE is reduced in order to spread the dose distribution over the anticipated tumor volume. The approach of delivering stable non-toxic isotopes to tumor, and then activating these atoms subsequently via an external radiation beam has mator advantages; problems associated with high uptake of these isotopes in competing cell pools are obviated, and the general tumor volume can be included in the treatment field of the activating beam. As long as the normal tissues supporting tumor show a low uptake of the isotope to be activated, and as long as the range of the reaction products is short, dose will be restricted to tumor, with a consequent high therapeutic ratio. Neutron Capture Therapy (NCT) is generally carried out by activating boron-10 with low energy neutrons. The range of the high LET, low OER particles from the 10 B(n, α) 7 Li reaction is approx. 10μ, or one cell diameter, a situation that is optimal for cell killing. Significant advantages may be gained by using the NCT procedure in conjunction with improved tissue penetration provided with epithermal or filtered beams, and new compounds showing physiological binding to tumor

  19. Effects of high thermal neutron fluences on Type 6061 aluminum

    International Nuclear Information System (INIS)

    Weeks, J.R.; Czajkowski, C.J.; Farrell, K.

    1992-01-01

    The control rod drive follower tubes of the High Flux Beam Reactor are contructed from precipitation-hardened 6061-T6 aluminum alloy and they operate in the high thermal neutron flux regions of the core. It is shown that large thermal neutron fluences up to ∼4 x 10 23 n/cm 2 at 333K cause large increases in tensile strength and relatively modest decreases in tensile elongation while significantly reducing the notch impact toughness at room temperature. These changes are attributed to the development of a fine distribution of precipitates of amorphous silicon of which about 8% is produced radiogenically. A proposed role of thermal-to-fast flux ratio is discussed

  20. Scattering of thermal neutron by the water molecule

    International Nuclear Information System (INIS)

    Rosa, L.P.

    The calculation of the differenctial cross section for scattering of thermal neutrons by water, taking into account the translational, rotational and vibrational motions of the water molecule, is presented according to Nelkin' model. Some modifications are presented which have been introduced in the original method to improve the results and an application has been made to reactor physics, by calculating the thermal neutron flux in a homogenous medium containing water and absorver. Thirty thermal energy groups have been used to compute the spectra. Within the limits of error, better agreement has been obtained between theory and experiments by using a modified Nelkin kernel consisting of substituting the asymptotic formulae for the rotational and vibrational motions by more exact expressions, similar to the Buttler model for heavy water