Small Angle Neutron Scattering & Neutron Reflectometry KuR is a group within the Laboratory for Neutron Scattering and Imaging (LNS), Paul Scherrer Institute (PSI), Division Research with Neutrons and Muons (NUM). We run the dedicated user instruments at the spallation neutron source SINQ:
In situ small angle neutron scattering (SANS) has been performed on three carbons, which adsorb methane, and a zeolite, which does not adsorb methane, loaded with CD4 at pressures of 0, 0.4 and 0.8 MPa. SANS is sensitive to CD4 adsorption. The change in the shape of the scattering patterns can be interpreted by an increase in methane density within the pores and the change of the scattering curves at high q suggests that the density of the adsorbed CD4 depended upon the local pore size. Estimates of the adsorbed density were in broad agreement with previous theoretical studies.. ...
When a binary mixture of ligand molecules is used to coat gold nanoparticles, stripe-like domains can occur. These nanodomains confer nanoparticles unique structure-dependent properties. The domain structure has been characterized primarily using scanning tunneling microscopy (STM) in air and in vacuum. Here we show the first STM images of striped nanoparticles in a solvent, 1-phenyloctane. We achieve stable imaging conditions on dodecanethiol hexanethiol (C12 : C6) 2 : 1 protected gold nanoparticles. These features are persistent across many images and retain their direction and overall morphology when recorded at different scan angles. We also perform small angle neutron scattering (SANS) on two hybrid C6 : C12 nanoparticle samples dissolved in chloroform. The hybrid nanoparticles have the same composition and size distribution as samples imaged with STM, but one of the two ligands (either C6 or C12) is deuterated. Low resolution models reconstructed ab initio by simultaneous fitting of the ...
14th International conference on applications of quasielastic neutron scattering. We would like to invite you to the international conference on quasielastic neutron scattering QENS 2016, which will take part from 5 to 8 of September 2016 in Potsdam. Established in Windsor in 1992 the conference series aims to bring together newcomers and experienced scientists to share the latest developments in the investigation of the dynamics phenomena in materials using quasi-elastic neutron scattering. This issue of the conference will be focused on functional materials for energy and information technology applications. Modeling, either to deeper understanding of experimental data, or in the prediction of new materials and phenomena will also be part of the conference. A special session will be dedicated to water.. ...
Preface. Contributors.. I Neutron Scattering.. I.1 Basic Concepts (Ferenc Mezei).. II Instrumentation.. II.1 Small-Angle Neutron Scattering.. II.1.1 Small-Angle Neutron Scattering at Reactor Sources (Kell Mortensen).. II.1.2 SANS Instruments at Pulsed Neutron Sources (Toshiya Otomo).. II.1.3 Ultra-Small-Angle Neutron Scattering.. II.1.3.1 Bonse-Hart USANS Instrument (Michael Agamalian).. II.1.3.2 Focusing USANS Instrument (Satoshi Koizumi).. II.2 Neutron Reflectometry (Naoya Torikai).. II.3 Quasielastic and Inelastic Neutron Scattering.. II.3.1 Neutron Spin Echo Spectroscopy (Michael Monkenbusch and Dieter Richter).. II.3.2 Neutron Backscattering (Bernhard Frick and Dan Neumann).. II.3.3 Time-of-Flight Spectrometry (Ruep E. Lechner).. II.4 Neutron Imaging (Nobuyuki Takenaka).. III Data Treatment and Sample Environment.. III.1 Practical Aspects of SANS Experiments (George D. Wignall).. III.2 Structure Analysis (Hideki Seto).. III.3 Calculation of Real Space Parameters and Ab Initio Models from ...
Small-angle neutron scattering data for lipid bilayers in excess water are presented. The method of solvent contrast variation was applied. The variation of scattering intensity with the scattering angle could be analyzed in terms of the model of scattering by quasi-2-dimensional systems of O. Kratky and G. Porod (1948). From this, the bilayer thickness of unilamellar vesicles of dimyristoyllecithin was detd. to be 41 .ANG. at 310 K. Several typical mixts. of different lecithins with varying chain lengths and of lecithin with phosphatidic acid were studied. By deuteration of 1 lipid component, a very large contrast between segregated phases could be achieved. It was thus possible to distinguish clearly between homogeneous mixts. and mixts. which exhibit a heterogeneous lipid organization. In the latter case, no intensity matching on solvent contrast variation was possible. Phase boundaries were detd. very accurately by performing contrast variation expts. with at most 2 mixts. of different initial compn
Past studies have established that the thickness of a vesicle bilayer formed from a mixture of conventional anionic and cationic surfactants is determined by a delicate balance of factors, including electrostatic interactions, van der Waals forces, and chain packing constraints. This complex balance of facto
Shale is an increasingly viable source of natural gas and a potential candidate for geologic CO2sequestration. Understanding the gas adsorption behavior on shale is necessary for the design of optimal gas recovery and sequestration projects. In the present study neutron diffraction and small-angle neutron scattering measurements of adsorbed CO2 in Marcellus Shale samples were conducted on the Near and InterMediate Range Order Diffractometer (NIMROD) at the ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory along an adsorption isotherm of 22 °C and pressures of 25 and 40 bar. Additional measurements were conducted at approximately 22 and 60 °C at the same pressures on the General-Purpose Small-Angle Neutron Scattering (GP-SANS) instrument at Oak Ridge National Laboratory. The structures investigated (pores) for CO2 adsorption range in size from Å level to ∼50 nm. The results indicate that, using the conditions investigated densification or condensation effects occurred in all
Relaxation processes for imidazolium-based ionic liquids (ILs) were investigated by means of an incoherent quasielastic neutron scattering technique. In order to clarify the cation and anion effects on the relaxation processes, ten samples were measured. For all of the samples, we found three relaxations at around 1 ps, 10 ps, and 100 ps-10 ns, each corresponding to the alkyl reorientation, the relaxation related to the imidazolium ring, and the ionic diffusion. The activation energy (E{sub a}) for the alkyl relaxation is insensitive to both anion and alkyl chain lengths. On the other hand, for the imidazolium relaxation and the ionic diffusion processes, E{sub a} increases as the anion size decreases but is almost independent of the alkyl chain length. This indicates that the ionic diffusion and imidazolium relaxation are governed by the Coulombic interaction between the core parts of the cations (imidazolium ring) and the anions. This is consistent with the fact that the imidazolium-based ILs ...
The nested neutron spectrometer (NNS) is a tool used for neutron spectroscopy. The NNS is used to measure the energy spectrum of neutrons in a neutron field. This type of detector is used in both research facilities (for characterization of neutron fields) and workplaces, where neutron radiation maybe encountered, for radiation protection purposes. Due to the difficulty associated with the detection of neutrons, the NNS is one of the few pieces of equipment capable of accurately determining the characteristics of a neutron field. The NNS operates under the same principle as a Bonner sphere neutron spectrometer. The sensitive part of the spectrometer is the Helium-3 proportional counter, which detects neutrons through the reaction 3He(n,p)3H. This particular reaction has a significant cross-section only at thermal neutron energies. In order for a higher energy neutrons to be detected their energies must be decreased, or moderated. To slow down neutrons at higher energies the NNS uses different ...
TY - JOUR. T1 - Molar mass dependence of polyethylene chain dynamics. A quasi-elastic neutron scattering investigation. AU - Arrighi, Valeria. AU - Tanchawanich, Jeerachada. AU - Telling, Mark T.F.. PY - 2013. Y1 - 2013. U2 - 10.1021/ma301922j. DO - 10.1021/ma301922j. M3 - Article. AN - SCOPUS:84872117016. VL - 46. SP - 216. EP - 225. JO - Macromolecules. JF - Macromolecules. SN - 0024-9297. IS - 1. ER - ...
Neutron radiation is a kind of ionizing radiation that consists of free neutrons. A result of nuclear fission or nuclear fusion, it consists of the release of free neutrons from atoms, and these free neutrons react with nuclei of other atoms to form new isotopes, which, in turn, may produce radiation. Free neutrons are unstable, decaying into a proton, an electron, and an anti-electron-neutrino with a mean lifetime of 887 seconds (about 15 minutes). Neutrons may be emitted from nuclear fusion or nuclear fission, or from any number of different nuclear reactions such as from radioactive decay or reactions from particle interactions (such as from cosmic rays or particle accelerators). Large neutron sources are rare, and are usually limited to large-sized devices like nuclear reactors or particle accelerators (such as the Spallation Neutron Source). Neutron radiation was discovered as a result of observing a beryllium nucleus reacting with an alpha particle thus transforming into a carbon nucleus ...
Neutron Scattering Instrument Scientist Neutron Scattering Science Division Oak Ridge National Laboratory Oak Ridge, Tennessee ORNL10-139-NSSD Project Description: The Neutron Sciences Directorate at Oak Ridge National Laboratory (ORNL) invites applications for Neutron Scattering Instrument Scientists. With the worlds highest flux reactor-based neutron source (the High Flux Isotope Reactor) and the worlds most intense pulsed accelerator-based neutron source (the Spallation Neutron Source), ORNL has become the worlds foremost center for neutron science. Research at these facilities will encompass the physical, chemical, materials, biological, and medical sciences and will provide opportunities for up to 2000 researchers each year from industry, research facilities, and universities all over the world. To learn more about Neutron Sciences at ORNL go to: http://neutrons.ornl.gov. The successful candidate will be a team member to provide operational support for specific instruments at the ...
Global Neutron Microscopes Market Professional Survey Report 2018 1 Industry Overview of Neutron Microscopes 1.1 Definition and Specifications of Neutron Microscopes 1.1.1 Definition of Neutron Microscopes 1.1.2 Specifications of Neutron Microscopes 1.2 Classification of Neutron Microscopes 1.2.1 1.2.2 1.3 Applications of Neutron Microscopes 1.3.1 Industrial 1.3.2 Agriculture 1.3.3 Bio-Medical 1.3.4 Others 1.4 Market Segment by Regions 1.4.1 North America 1.4.2 China 1.4.3 Europe 1.4.4 Southeast Asia 1.4.5 Japan 1.4.6 India 2 Manufacturing Cost Structure Analysis of Neutron Microscopes 2.1 Raw Material and Suppliers 2.2 Manufacturing Cost Structure Analysis of Neutron Microscopes 2.3 Manufacturing Process Analysis of Neutron Microscopes 2.4 Industry Chain Structure of Neutron Microscopes 3 Technical Data and Manufacturing Plants Analysis of Neutron Microscopes 3.1 Capacity and Commercial Production Date of Global Neutron Microscopes Major Manufacturers in 2017 3.2 Manufacturing Plants ...
Neutron flux measurements have been made (1)2 of low-level neutron sources present in several types of neutron-producing facilities. The flux levels or distribution of thermal, epithermal, and fast neutrons have been measured in radioisotope sources, spent fuel element gamma irradiation facilities, and electron linear accelerators. Sensitivities greater than 1 neutron per sq cm per sec have been achieved for thermal neutrons. Neutron flux measurements may be made by several methods (2). Foil activation (3) is a convenient and simple technique. The foils containing materials of known cross-section are exposed to the neutrons, and the flux determinations are made by measurement of the induced activities in the irradiated foils. This technique is widely used for measuring neutron fluxes and spectra in nuclear reactors and critical facilities where the neutron fluxes are large (106 to 1014 neutrons per sq cm per sec). To measure neutron fluxes of smaller magnitude, such as those found in isotope ...
We collected inelastic neutron scattering (INS) spectra of homologous disaccharide (C12H22O11)/H2O mixtures at a very low temperature by using indirect geometry time-of-flight spectrometer TOSCA at the ISIS pulse neutron facility (DRAL, UK). The aim of this work is to investigate the vibrational behaviour of trehalose, maltose and sucrose/H2O mixtures with INS in order to characterize the structural changes induced by these disaccharides on the H2O hydrogen-bonded network. A higher degree of crystallinity for the trehalose/H2O system is observed in the vibrational region corresponding to the ice bending modes. This feature could justify the better cryptobiotic action of trehalose compared with maltose and sucrose. On the other hand, the better bioprotective effectiveness could be explained by the higher destructuring effect of trehalose, emphasized by the analysis of the librational modes region. ...
Mixtures of the partly fluorinated cationic surfactant HFDePC (N-(1, 1,2,2-tetrahydroperfluorodecanyl)pyridinium chloride and deuterated headgroup) with C(16)TAC, hexadecyl-trimethylammonium chloride, have been investigated using small angle neutron scattering with contrast matching. Earlier results from this system suggested that a demixing occurred, into two coexisting populations of micelles, hydrocarbon-rich and fluorocarbon-rich, respectively. The present results could be explained by one type of mixed micelles with an inhomogeneous distribution of fluorinated and hydrogenated surfactants within the micelles although a demixing cannot be definitely excluded.. ...
The structural characterization of peripheral membrane proteins represents a tremendous challenge in structural biology due to their transient interaction with the membrane and the potential multitude of protein conformations during this interaction. Neutron reflectometry is uniquely suited to address this problem because of its ability to structurally characterize biological model systems nondestructively and under biomimetic conditions that retain full protein functionality. Being sensitive to only the membrane-bound fraction of a water-soluble peripheral protein, neutron reflectometry obtains a low-resolution average structure of the protein-membrane complex that is further refined using integrative modeling strategies. Here, the authors review the current technological state of biological neutron reflectometry exemplified by a detailed report on the structure determination of the myristoylated human immunodeficiency virus-1 (HIV-1) Gag matrix associated with phosphoserine-containing model ...
The elements Be, Bi, Mg, Pb, Zr, Al, Ca, Na, Sn, Rb and Ce are the metallic elements of small thermal neutron absorption cross section. Except Be and Zr, they are all soft metals. But the reasons for these small thermal neutron absorption cross-sections are not known. To clarify its mechanism, the thermal neutron absorption cross-sections of elements were plotted on the TC-YM diagram. They lie on a line connecting the elements of low Youngs modulus on the TC-YM diagram. The author at first considered that the neutron absorption characteristics of elements relate to the neutron multiple number which means the number of neutrons per proton in the nucleus. The absorption cross-section of elements roughly increases with increasing neutron multiple number. Among the elements of small neutron absorption cross section, only Zr and Be are the elements of high melting temperature. Zr should not show the small neutron absorption cross section inherently. But in fact, Zr is exceptional both on the TC-YM diagram
ZENG, X. B., UNGAR, G., SPELLS, S. J. and KING, S. M. (2005). Real-time neutron scattering study of transient phases in polymer crystallization. Macromolecules, 38 (17), 7201-7204. Full text not available from this repository ...
en] The aim of the project is the preparation of micellar nanocarriers made of biocompatibles copolymers and their structural analysis by Small Angle Neutron Scattering (SANS). These micelles could be used in drug delivery applications to fight cancer1. The hydrophobic polycaprolactone (PCL) core is intended to incorporate the drug. The corona of hydrophilic polyethylene oxide (PEO) stabilizes the nanocarriers with respect to the plasma proteins. The pH in the neighborhood of the tumoral cells is lower than in the healthy cells. We incorporated a pH-sensitive sequence of poly(2-vinylpyridine) (P2VP). As a result, these micelles are expected to deliver their drug near the cancerous cells without affecting the healthy cells. When the pH is acidic, the P2VP is protonated and the chains are repulsive. The micellar size is then larger than in basic pH, when the P2VP is precipitated on the PCL core. We prepared PCL65-b-P2VP31 / PCL65-b-PEO114 and PCL32-b-P2VP52 / PCL36-b-PEO114 50:50 mixtures of ...
Purpose: In proton therapy, it could be desirable to measure out-of-field fast neutron doses at critical locations near and outside the patient body. Methods: The working principle of a novel clinical neutron dose monitor is verified by MCNPX simulation. The device is based on a small PE moderator of just 5.5cm side length for easy handling covered with a thermal neutron suppression layer. In the simulation, a polystyrene phantom is bombarded with a standard proton beam. The secondary thermal neutron flux produced inside the moderator by the impinging fast neutrons from the treatment volume is estimated by pairs of α-Al2O3:C (TLD500) chips which are evaluated offline after the treatment either by TL or OSL methods. The first chip is wrapped with 0.5mm natural Gadolinium foil converting the thermal neutrons to gammas via (n,γ) reaction. The second chip is wrapped with a dummy material. The chip centers have a distance of 2cm from each other. Results: The simulation shows that the difference of ...
We review the current state of the field of neutron scattering as applied to studies of mineral behaviour. Neutron scattering is a particularly versatile tool because it is able to measure both structure (diffraction) and dynamics (spectroscopy) of materials at an atomic level, and because it is able to measure both coherent and incoherent scattering processes. As a result, there is a wide range of phenomena that can be studied using neutron scattering. The versatility of the tool is shown to arise within a general theoretical framework. Applications of neutron scattering in the Earth and Mineral Sciences are described. ...
Neutron scattering has become a widely applied technique for studying problems in polymer science and technology. This is the first book written specifically for non-specialists that introduces the theoretical models and experimental techniques needed to understand results obtained from neutron scattering. In attempting to present a readable text that requires little expert knowledge, the authors have produced a practical volume that fills the gap between the often technical, pedagogic research articles that have characterized the literature and the almost entire absence of information available to the polymer scientist who desires a firmer grasp of the advantages offered by neutron scattering in materials research. Researchers and graduate students interested in polymers and neutron scattering will find this book useful and informative.
70585S02-II The most favored techniques for monochromatizing neutron beams, needed for medical, industrial and scientific purposes, are mechanical reflection and diffraction methods, both of which have limited efficiency and great cost. Furthermore, neutrons can be used for imaging, particularly for objects that are invisible to x-rays, light, or other techniques; however, neutron imaging has not been developed due to a lack of sufficient optics. This project will design and fabricate high-performance neutron optics that use compound refractive lenses. Such lenses can be used to form direct neutron images of objects or to monochromatize, collect, collimate, or focus neutrons. Phase I designed and fabricated prototype compound refractive lenses for neutrons. The same lenses were used both for constructing a monochromator and for imaging. Theory and experiments demonstrated a working monochromator as well as the successful thermal neutron imaging of both inorganic and biological materials. Phase ...
Joe is an instrument scientist for the Magik Reflectometer at the NCNR, and applies neutron reflectometry, NR, to a variety of disciplines including energy storage and conversion, hydrogen interactions, biology, and magnetic materials, in addition to developing Neutron Reflectometry techniques, instrumentation and sample environments. Neutron reflectometry measures the reflected intensity of a thin monochromatic neutron beam as a function of the grazing incidence angle relative to a flat smooth sample surface. The sample typically consists of layers or coatings with thickness of 1-500nm (either intentionally deposited or as the result of surface or interface reactions). By analyzing NR data, which consists of oscillations in the intensity, one determines a depth profile of the scattering length density in the sample with up to sub-angstrom level precision and accuracy. For neutrons, the scattering length density, which can be determined from the composition, can vary quite significantly for ...
A neutron is a sub-atomic (meaning it is smaller than an atom) particle. The nucleus of an atom is made up of neutrons and protons. Neutrons and protons are almost exactly the same size (a neutron has about 1/10th of one percent more mass). A neutron does not have an electrical charge, unlike protons (which have a charge of +1) and electrons (which have a charge of -1). Neutrons are much larger than electrons; the mass of a neutron is about 1,839 times that of an electron!. The number of protons in the nucleus of an atom determines what type of element the atom is. The number of protons is called the elements atomic number. For example, hydrogen has an atomic number of one, since all hydrogen atoms have one proton in their nucleus. Carbon has 6 protons, so its atomic number is 6; oxygen has 8 protons, so its atomic number is 8. Uranium has 92 protons, so its atomic number is 92! If we count the number of protons plus neutrons, we get an atoms atomic mass. Most elements come in different ...
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Neutrons are neutral particles. Together with protons, they are the building blocks of the atomic nuclei. Neutrons weigh slightly more than the positively charged protons. The wave-particle dualism described by quantum mechanics implies that neutrons also behave like material waves. The wavelength of thermal neutrons is in the range of the atomic distances in condensed matter (crystals, liquids).. Since neutrons are neutral they penetrate deep into matter and they are scattered by atomic nuclei and electron magnetic moments. In this way, the arrangement and motion of atoms (atomic nuclei) or magnetic structures can be determined in a suitable scattering experiment.. As with X-ray scattering, structures on an atomic, molecular or nanoscopic scale become visible. In addition, neutrons allow the simultaneous analysis of motions from fast single atom vibration to slow large-scale fluctuations. Further light elements -in particular hydrogen-have the same visibility as heavy ones and the scattering ...
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TY - JOUR. T1 - Dynamical Transitions at Low Temperatures in the Nearest Hydration Shell of Phospholipid Bilayers. AU - Syryamina, V. N.. AU - Dzuba, S. A.. PY - 2017/2/9. Y1 - 2017/2/9. N2 - For the so-called dynamical transition from harmonic to anharmonic (or diffusive) motions in biological systems, the presence of hydration water is important. To explain the molecular mechanism of this transition, the information on molecular motions in the nearest hydration shell would be helpful. In this work, to study molecular motions in the nearest hydration shell of spin-labeled model biological membranes, a pulsed version of electron paramagnetic resonance, electron spin echo envelope modulation (ESEEM) spectroscopy, is used. For hydration by deuterium water, the 2H ESEEM frequency spectra resemble the solid-state 2H NMR line shape that is widely used for structural and dynamical studies. Two types of model membranes were investigated and compared: bilayers consisting of unsaturated lipid ...
Shortly after the start of science with neutrons in Garching more research reactors were planned and built in Germany. The most powerful one was built in Karlsruhe, the FR 2. Capable of producing 44 MW it was in operation from 1961 - 1981. Besides basic research science this reactor was used to produce radioisotopes for diagnosis and therapy in nuclear medicine. Forschungszentrum Jülich, at that time the Kernforschungsanlage Jülich, hosted two of the reactors. FRJ-1 MERLIN was in operation from 1962 - 1985. Meanwhile this reactor has been completely dismantled. The other one, FRJ-2 DIDO was in operation from 1962 - 2006. This reactor was able to produce a power of 23 MW in its final stage of extension and served exclusively as a neutron source for scientiifc research. Instrumentation within the neutron laboratory ELLA included small angle neutron scattering (SANS) instruments, a double crystal diffractometer, backscattering and time-of-flight spectrometers, a diffractometer for diffuse ...
Neutron quasielastic scattering experiments on liquid lithium (at 500 and 830 K) and a lithium-hydrogen melt (99 at.% Li 7 and 1 at.% H at 830 K) have been performed. The characteristics of the diffusion mobility for lithium and hydrogen atoms have been extracted from the experimental results and analyzed with the use of phenomenological and theoretical models. The self-diffusion coefficient in liquid lithium obtained for both temperatures is in agreement with values in the literature. The mechanism of hydrogen diffusion mobility in liquid lithium is discussed. It has been concluded that the hydrogen in the liquid lithium exists and diffuses in the form of the hydride LiH.
Objective: Undesired neutron contamination imposed to patients during treatment is among the main factors increasing the risk of secondary cancer in radiotherapy. This additional undesirable dose is due to neutron contamination production in high-energy accelerators. In this study, neutron contamination is investigated in the presence of wedge and block in 15 MV photon fields of Siemens Primus linear accelerator. Materials and Methods: Neutron production by 30°, 45°, and 60° wedges and cerrobend block was investigated. Measurements were conducted in a 10 cm × 10 cm field at the source to -surface distance of 100 cm at 0.5, 2, 3, and 4 cm depths of a 30 cm × 30 cm × 30 cm Perspex phantom using the CR-39 passive film detectors. Chemical etching was performed using sodium hydroxide solution with 6.25 M concentration as the etchant at 85°C for 3 h. Results: The neutron dosimetry results reveal that the presence of wedge and block increases the neutron contamination. However, the 45° wedge is ...
Dr Beau Webber - Research home page : Dr. J.B.W.Webber, Director and Designer, Lab-Tools Ltd., Canterbury Enterprise Hub, University of Kent, VT2 7NJ, United Kingdom. Functional Materials Group, School of Physical Sciences, University of Kent, Canterbury, Kent, CT2 7NR, United Kingdom. Institute of Petroleum, Heriot-Watt University, Edinburgh. EH14 4AS, United Kingdom. Nano-science, study of liquids in confined geometry and at surfaces, nano-metrology and characterisation of porous materials : Porous silica/rocks/clays/sediments, gas hydrates/clathrates, melanised fungal cells. - Nuclear Magnetic Resonance (NMR) - Neutron Diffraction (NS) - Small Angle Neutron Scattering (SANS) - NMR Cryoporometry - NMR diffusion in a magnetic gradient - Thermoporosimetry - Differential Scanning Thermal Analysis - Gas Adsorption.
The nature of the interaction between a neutron and an atomic nucleus depends upon the characteristics of the nucleus involved. Consequently some information concerning nuclear structure can be derived from studies of the scattering of neutrons by nuclei. The experimental observations can be compared with the theoretical predictions and may support the theory or suggest a different approach to the theoretical problem. One method of studying neutron scattering is to observe in a cloud chamber the tracks produced by nuclei recoiling from collisions with the neutrons. From measurements of the lengths of the recoil tracks and their angles with respect to the incident neutron direction, the distribution of the scattered neutrons in angle and energy may be deduced ...
The existence and stability of atoms relies heavily on the fact that neutrons are slightly more massive than protons. The experimentally determined masses differ by only around 0.14 percent. A slightly smaller or larger value of the mass difference would have led to a dramatically different universe, with too many neutrons, not enough hydrogen, or too few heavier elements. The tiny mass difference is the reason why free neutrons decay on average after around ten minutes, while protons - the unchanging building blocks of matter - remain stable for a practically unlimited period.. In 1972, about 40 years after the discovery of the neutron by Chadwick in 1932, Harald Fritzsch (Germany), Murray Gell-Mann (USA), and Heinrich Leutwyler (Switzerland) presented a consistent theory of particles and forces that form the neutron and the proton known as quantum chromodynamics. Today, we know that protons and neutrons are composed of up quarks and down quarks. The proton is made of one down and two up ...
Higher plant thylakoid membranes contain a protein kinase that phosphorylates certain threonine residues of light-harvesting complex II (LHCII), the main light-harvesting antenna complexes of photosystem II (PSII) and some other phosphoproteins (Allen, Biochim Biophys Acta 1098:275, 1992). While it has been established that phosphorylation induces a conformational change of LHCII and also brings about changes in the lateral organization of the thylakoid membrane, it is not clear how phosphorylation affects the dynamic architecture of the thylakoid membranes. In order to contribute to the elucidation of this complex question, we have investigated the effect of duroquinol-induced phosphorylation on the membrane ultrastructure and the thermal and light stability of the chiral macrodomains and of the trimeric organization of LHCII. As shown by small angle neutron scattering on thylakoid membranes, duroquinol treatment induced a moderate (~10%) increase in the repeat distance of stroma membranes, and ...
We plan to study the effect of both oscillatory and steady state shear flow on the mesoscopic structure of polymer blends. A central feature of this proposal is the design and build of a rheometer for use with small angle neutron scattering. This will enable the simultaneous measurement, and hence correlation, of rheological properties and structure. It differs from existing facilities in that it is specifically aimed at viscoelastic materials with a high viscosity. We will study both polystyrene blended with is deuterated analogue, and blends of polystyrene/polyvinylmethylether and polyethyleneoxide/ polymethylmethacrylate. In each case both blend components will be highly entangled. We will meaure the anisotropy of the scattering pattern in the one phase region, and use this information to verify or otherwise recent theoretical predictions. We will also measure the structures that exist within the two-phase region, caused by shear induced phase separation. ...
Small angle neutron scattering (SANS) has brought insight into how ions are transported at the nano level in stacked membranes of graphene, materials that have many unique properties. The research was aimed to develop graphene into a more versatile material.
The workshop on the Molecular Basis of Polymer Networks, held October 5- 7, 1988 in 1iilich, FRG, continued a series of workshops jointly organized by the Institute Laue Langevin (ILL) in Grenoble, and the Institute of Solid State Physics of the KFA, 1iilich. The aim of this workshop was to provide a platform for discussions between theoreticians and experimentalists interested in the physics of polymer networks, in the hope that the two types of discussion would be synergistic. As revealed by the title of this workshop, the main focus of the lectures was on molecular aspects of the problem. The individual parts of these proceedings cover various approaches. Following quite general comments from a physicist examining the situation from outside, various new theoretical concepts are developed. During the last decade the advent of Small Angle Neutron Scattering (SANS) has allowed the molecular structure of polymer networks to be studied and thus the reliability of the theories to be tested directly at
D11 is the archetype of a long, pinhole geometry instrument for small angle neutron scattering (SANS), designed for the study of large scale structures in soft matter systems, chemistry, biology, solid state physics and materials science. This instrument was upgraded as a part of the ILLs Millennium Programme. ...
Scientists test how well a piece of plywood or product will perform in a real-life situation by putting the product through several wet-dry cycles to mimic outdoor conditions. Wood swells when wet and contracts when dry, testing the strength of the wood-adhesive bond. While changes like these are visible to the naked eye, observing these changes at smaller scales requires advanced imaging tools, such as X-ray computed tomography, X-ray fluorescence microscopy, and small angle neutron scattering to study the way the adhesive flows into air spaces in the wood structure, then enters cell walls, especially beneath the woods surface.. Researchers found that smaller adhesive molecules are more effective than larger molecules at entering the cell walls and minimizing the effects of moisture on the properties of the wood nearest the bond line. Additionally, research results have helped scientists identify the most important interactions between adhesive and nanoscale cell wall structures for creating ...
Structure-specific DNA-induced conformational changes in Taq polymerase revealed by small angle neutron scattering. JOURNAL OF BIOLOGICAL CHEMISTRY 279, No.37 (Sep 2004): 39146-39154. Ho DL, Byrnes WM, Ma WP, Shi, Y, Callaway DJE, Bu ZM. ...
Two small neutron sources of /sup 252/Cf and /sup 241/Am-Be radioisotopes were used for design of neutron beams applicable to low-intensity neutron and gam
Neutrons enable us to gaze deep into the heart of matter. As the building blocks of atomic nuclei, neutrons are the ideal probes for investigating crystals, membranes and other systems at the atomic level. In his keynote speech at the 2010 end-of-year ceremony, Prof. Dieter Richter of the Jülich Centre for Neutron Science gave exciting insights into the far-reaching opportunities offered by neutron research to representatives of science, industry and politics. Gallery: Neutron Research: Neutrons: A Look at Complexity …. ...
On-Orbit Status Report. Radiation Dosimetry Inside ISS-Neutron (RaDI-N): After retrieving the RaDI-N hardware from the Russian crewmembers, a USOS crewmember deployed eight Space Bubble Detectors around the ISS for the Radi-N experiment. The Canadian Space Agency (CSA) RaDI-N investigation will be conducted by measuring neutron radiation levels while onboard the ISS. RaDI-N uses bubble detectors as neutron monitors which have been designed to only detect neutrons and ignore all other radiation. At Home in Space Questionnaire and Photo: The crew completed an At Home in Space questionnaire and took photos to document ISS culture. This Canadian Space Agency experiment assesses culture, values, and psychosocial adaptation of astronauts to a space environment shared by multinational crews on long-duration missions. It is hypothesized that astronauts develop a shared space culture that is an adaptive strategy for handling cultural differences and they deal with the isolated confined environment of the ...
The upgraded IGISOL facility with JYFLTRAP, at the accelerator laboratory of the University of Jyväskylä, has been supplied with a new cyclotron which will provide protons of the order of 100 μA with up to 30 MeV energy, or deuterons with half the energy and intensity. This makes it an ideal place for measurements of neutron-induced fission products from various actinides, in view of proposed future nuclear fuel cycles. The groups at Uppsala University and University of Jyväskylä are working on the design of a neutron converter that will be used as neutron source in fission yield studies. The design is based on simulations with Monte Carlo codes and a benchmark measurement that was recently performed at The Svedberg Laboratory in Uppsala. Inorder to obtain a competitive count rate the fission targets will be placed very close to the neutron converter. The goal is to have a flexible design that will enable the use of neutron fields with different energy distributions. In the present paper, ...
Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states. The excited nucleus often decays immediately by emitting gamma rays, or particles such as beta particles, alpha particles, fission products, and neutrons (in nuclear fission). Thus, the process of neutron capture, even after any intermediate decay, often results in the formation of an unstable activation product. Such radioactive nuclei can exhibit half-lives ranging from small fractions of a second to many years.. Neutron activation is the only common way that a stable material can be induced into becoming intrinsically radioactive. All naturally occurring materials, including air, water, and soil, can be induced (activated) by neutron capture into some amount of radioactivity in varying degrees, as a result of production of neutron-rich radioisotopes. Some atoms require more than one neutron to become ...
2006 i-xx + 471 pages. ISBN 0-939950-75-8; ISBN13 978-0939950-75-1. For over half a century neutron scattering has added valuable information about the structure of materials. Unlike X-rays that have quickly become a standard laboratory technique and are available to all modern researchers in physics, chemistry, materials and earth sciences, neutrons have been elusive and reserved for specialists. A primary reason is that neutron beams, at least so far, are only produced at large dedicated facilities with nuclear reactors and accelerators and access to those has been limited. Yet there are a substantial number of experiments that use neutron scattering.. While earth science users are still a small minority, neutron scattering has nevertheless contributed valuable information on geological materials for well over half a century. Important applications have been in crystallography (e.g. atomic positions of hydrogen and Al-Si ordering in feldspars and zeolites, Mn-Fe-Ti distribution in oxides), ...
ISIS beam hall. As the name suggests, ISIS produces neutrons (and muons). It isnt a nuclear reactor, it provides neutrons for research. Neutrons can be used (like X-rays) to probe the structure and motions of things on an atomic level. You can see atoms move and how they are placed. How cool is that? Atoms. We can see atoms with neutrons (something that is impossible with any kind of microscope). Neutrons are also used to look at stress and strain in materials. This may not sound so sexy but dont you think you want to know if that airplane wing has hairline fractures? About the only way you can see this is neutrons. Neutrons are also used to investigate the structure of piezoelectric materials. Again, this may not sound sexy, but piezoelectric materials are what make your iPhone work. I use neutrons to look at biological stuff. It is a major part of my research, I look at water (molecules!) around things like cell membranes and drugs trying to answer questions like how does water get inside ...
Accepted in the Journal of Molecular Structure. A nice article by the official author (M.R.H.) that combines multiple experimental methodologies with quantum chemical simulations using density functional theory to characterize a molecular inorganic solid with constituents known to have interesting ferroelectric and nonlinear optical (NLO) properties. We can design remarkably complicated molecules and perform rigorous quantum chemical analyses to tailor properties, but the simple molecules still hold the greatest interest to the application-focused experimentalists (something about being able to make them…).. If this were a terahertz spectroscopy (THz) paper, it would serve as yet another shining example of how one cannot perform isolated-molecule calculations for the assignment of vibrational modes (as the molecules in this system, glycine and sulfate, are THz-transparent). Relevant to inelastic neutron scattering (INS) and optical (infrared and Raman) spectroscopic techniques, the interesting ...
Graphene oxide membranes were recently suggested for applications in separation of ethanol from water using a vapor permeation method. Using isotope contrast, neutron reflectivity was applied to evaluate the amounts of solvents intercalated into a membrane from pure and binary vapors and to evaluate the selectivity of the membrane permeation. Particularly, the effect of D2O, ethanol and D2O-ethanol vapours on graphene oxide (GO) thin films (similar to 25 nm) was studied. The interlayer spacing of GO and the amount of intercalated solvents were evaluated simultaneously as a function of vapour exposure duration. The significant difference in neutron scattering length density between D2O and ethanol allows distinguishing insertion of each component of the binary mixture into the GO structure. The amount of intercalated solvent at saturation corresponds to 1.4 molecules per formula unit for pure D2O (similar to 1.4 monolayers) and 0.45 molecules per formula unit (one monolayer) for pure ethanol. ...
TY - JOUR. T1 - A systematic study of equilibrium structure, thermodynamics, and rheology of aqueous CTAB/NaNO3 wormlike micelles. AU - Helgeson, Matthew E.. AU - Hodgdon, Travis K.. AU - Kaler, Eric W.. AU - Wagner, Norman J.. PY - 2010/9/1. Y1 - 2010/9/1. N2 - We present a systematic study of the self-assembly of wormlike micelles (WLMs) comprised of cetyltrimethylammonium bromide (CTAB) and sodium nitrate (NaNO3) in aqueous solution as a function of CTAB concentration, NaNO3 concentration, and temperature throughout the dilute and semi-dilute regions of the phase diagram where linear micelles are observed. Combining measurements using isothermal titration calorimetry, rheometry, flow-birefringence, cryo-transmission electron microscopy (cryo-TEM), and small angle neutron scattering (SANS) enables complete characterization of the structure, thermodynamics, and rheology of CTAB/NaNO3 micelles. The addition of NaNO3 is found to increase the micellization enthalpy as well as the micellar scission ...
Neutron crystallography compliments x-ray crystallography in its ability to precisely locate hydrogen and light atoms in various materials. This information is important for biological applications (for example, monitoring protein dynamics), and material research and security applications (for example, explosives detection, etc.). However, the detectors available for scattered neutron radiation are still inadequate. The ideal detector would provide fast response, high spatial resolution, high neutron efficiency, low gamma sensitivity, and large detection area at reasonable cost. This project will develop a detector, based on a finely-structured plastic scintillator coupled to a state-of-the-art digital readout, that meets the above requirements The structure of the scintillators body will enhance light channeling to the digital optical detector, promoting very high spatial resolution. The scintillator will be loaded with neutron sensitive elements, such as B and Gd. In Phase I, a 5 x 5 cm2 ...
The crystal structure of a natural davyne [(Na3.98K 1.79Ca1.89Mg0.02Fe0.01) Σ7.69(Al5.99Si6.01O24)(SO 4)0.65Cl1.96, a = 12.7908(5) Å, c = 5.3469(2) Å and V = 757.59(6) Å3, space group P6 3], its thermoelastic behaviour and low-temperature induced structural evolution have been investigated by single-crystal neutron diffraction and in situ single-crystal X-ray diffraction within the range 110 ≤ T (K) ≤ 293. X-ray and neutron structure refinements provided a better picture of the disordered configuration of the SO4-groups and of the cation sites into the [0 0 0 1]-channel. No evidence of phase transition or change of the thermoelastic behavior have been observed within the T-range investigated. The volume thermal expansion coefficient is αV = 4.2(4) * 10-5 K-1, and the axial thermal coefficients are αa = 1.4(1) *10-5 K -1 and αc = 1.6(1) *10-5 K -1. A series of structure refinements based on X-ray intensity data collected between 293 and 110 K showed that the structural evolution of ...
We have measured the -ray energy spectrum from the thermal neutron capture, Gd, on an enriched Gd target (GdO) in the energy range from 0.11 MeV up to about 8 MeV. The target was placed inside the germanium spectrometer of the ANNRI detector at J-PARC and exposed to a neutron beam from the Japan Spallation Neutron Source (JSNS). Radioactive sources (Co, Cs, and Eu) and the Cl(,) reaction were used to determine the spectrometers detection efficiency for rays at energies from 0.3 to 8.5 MeV. Using a Geant4-based Monte Carlo simulation of the detector and based on our data, we have developed a model to describe the -ray spectrum from the thermal Gd(,) reaction. While we include the strength information of 15 prominent peaks above 5 MeV and associated peaks below 1.6 MeV from our data directly into the model, we rely on the theoretical inputs of nuclear level density and the photon strength function of Gd to describe the continuum -ray spectrum from the Gd(,) reaction. Our model combines these two ...
Our long-term scientific objective is the rational design and fabrication of electrochemical interfaces of specific function, via modification of the electrode with thin films of electroactive polymers. This requires us to understand the relationship between electrode performance and structure. From a series of experiments performed on the TAS8 reflectometer at Riso National Labs, we have studied the spatial distributions of polymer and solvent within poly(o-toluidine)(PoT) films in their reduced form, as functions of film thickness and pH in perchloric acid solutions. We intend to use our in-situ neutron reflectivity data to rationalize electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) data on redox driven PoT ion and solvent transfer dynamics. (C) 2000 Elsevier Science B.V. All rights reserved ...
Neutrons play a vital role in the portfolio of analysis techniques for research on subjects as varied as clean energy and the environment, pharmaceuticals and health care, through to nanotechnology, materials engineering and IT.. This is tremendous news for the science community, both in the UK and much further afield, said Professor Andrew Harrison, UK Director at the Institut Laue Langevin, Grenoble, France.. The ISIS Second Target Station will open research into new types of materials that has not been previously possible at ISIS, and we look forward to a world of new science flowing from the new instrument suite.. Ian Anderson, Associate Director for Neutron Sciences at Oak Ridge National Laboratory, USA also added his congratulations. This is a remarkable achievement by the ISIS team and adds an exciting new dimension to the capabilities of the European neutron scattering toolkit, he said.. ISIS is the worlds leading spallation neutron facility and has performed world class ...
Gilbert RJ, Heenan RK, Timmins PA, Gingles NA, Mitchell TJ, Rowe AJ, Rossjohn J, Parker MW, Andrew PW, Byron O. 1999. Studies on the structure and mechanism of a bacterial protein toxin by analytical ultracentrifugation and small-angle neutron scattering. J Mol Biol, 293 (5), pp. 1145-1160. , Show Abstract , Read more Pneumolysin, an important virulence factor of the human pathogen Streptococcus pneumoniae, is a pore-forming toxin which also possesses the ability to activate the complement system directly. Pneumolysin binds to cholesterol in cell membrane surfaces as a prelude to pore formation, which involves the oligomerization of the protein. Two important aspects of the pore-forming activity of pneumolysin are therefore the effect of the toxin on bilayer membrane structure and the nature of the self-association into oligomers undergone by it. We have used analytical ultracentrifugation (AUC) to investigate oligomerization and small-angle neutron scattering (SANS) to investigate the changes ...
Whereas classic types of thermal neutron detectors have been in use since the 1950s, a practical semiconductor material has remained elusive. Excellent at absorbing neutrons, lithium quickly emerged as the most promising material for neutron detecting devices. But integrating lithium into a semiconductor and making it stable (lithium crumbles when it meets water) was another story.. You can find good semiconductors, but they dont have lithium, Kanatzidis said. Or you can find stable lithium compounds that are not good semiconductors. We found the best of both worlds. The specific lithium-6 isotope, which is reasonably abundant and low cost, is a strong neutron absorber.. In their study, Kanatzidis and his team discovered the right combination of materials to make a working device that also keeps lithium stable. Their new material - lithium-indium-phosphorous-selenium - is layered in structure and enriched with the lithium-6 isotope.. The crystal structure is special, Kanatzidis said. The ...
X-Ray and neutron diffraction measurements are presented for liquid dioxane. The analysis of intramolecular terms by the MCGR method yields bond length parameters in good agreement with previous studies. The liquid structure is similar to that of cyclohexane and is characterized by a weak orientational correlation with a regular long range order arising from the distribution of molecular centres, typical of a pseudo-spherical van der Waals molecule.. ...
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MCNP{trademark} and LAHET{trademark} are two of the codes included in the LARAMIE (Los Alamos Radiation Modeling Interactive Environment) code system. Both MCNP and LAHET are three-dimensional continuous-energy Monte Carlo radiation transport codes. The capabilities of MCNP and LAHET are currently being merged into one code for the Accelerator Production of Tritium (APT) program at Los Alamos National Laboratory. Concurrently, a significant effort is underway to improve the accuracy of the physics in the merged code. In particular, full nuclear-data evaluations (in ENDF6 format) for many materials of importance to APT are being produced for incident neutrons and protons up to an energy of 150-MeV. After processing, cross-section tables based on these new evaluations will be available for use fin the merged code. In order to utilize these new cross-section tables, significant enhancements are required for the merged code. Neutron cross-section tables for MCNP currently specify emission data for neutrons
Fast neutrons passive dosimetry with Si - diodes. Since several years, Si-diodes have been used for the fast neutron dosimetry in the case of high level exposure, accidental enclosed. This work describes the results of tests performed with the diodes of a new production, presents their characteristics and the analysis of the possibilities of their use. The diodes of two different sensitivities were irradiated at the SILENE reactor (irsn Valduc). We studied: the reproducibility of reading and the influence of its repetition, the homogeneity of the lot of diodes studied, the evolution of the signal with the time after irradiation, the influence of the thermal treatment on this evolution, the response of two types of diodes to the neutrons of SILENE reactor in two configurations, the detection threshold expressed in tissue kerma. The results obtained are presented, analysed and discussed. The principal knowledge is formulated in the conclusion ...
Zn7/3Sb2/3O4 is a secondary phase in ZnO-based varistors. Acceptor impurities, such as Li+, increase the resistivity. This effect is produced by a modification of the grain boundary barriers. The role of the cationic distribution in the mentioned events is worth clarifying. The Li0.5Zn5/3Sb2.5/3O4 room-temperature structure was determined by means of a neutron diffraction and synchrotron X-ray diffraction investigation. The title compound was prepared by conventional ceramic process. The elemental composition of the investigated sample was verified by means of electron microscopy-energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The neutron experiment was performed at the high-intensity neutron diffractometer with position-sensitive detector at the D1B beamline of the Laue-Langevin Institute, Grenoble. The high resolution synchrotron measurement was carried out at MCX beamline of Elettra Sincrotrone Trieste. Rietveld analysis was performed with the FullProf program. Li0.5Zn5
With the anthrax threat becoming a reality, it is very important to have an effective way to sterilize areas contaminated by anthrax. Anthrax spores are the dormant form of the anthrax bacteria. They can germinate in tissues, producing new bacteria that release lethal toxins. Neutrons can be a powerful tool in our defense against anthrax contamination. Neutrons are elementary particles that have no charge, which allows them to be very penetrating, killing the anthrax spores on the surface and inside the containers. So neutrons have an advantage over other forms of radiation if deep penetration is required to kill biological organisms. A Cf neutron source allows for a low cost method of decontamination. It emits most neutrons in the 100 keV to 2 MeV energy regions, and a neutron in this energy region is 20 times more deadly than electrons or gamma rays in killing anthrax spores. If we just consider the first neutron collision with anthrax spores and that all the anthrax spores will not survive at the
Physically, this is the speed of the neutron. A 2 MeV neutron is traveling at about 45 million miles/hr. Neutrons moving this fast dont often linger to induce fission in other atoms. Statistically they are likely to leave the reactor core before an interaction occurs. For this reason it is desirable to slow them down. Neutrons are slowed by allowing them to bounce off lighter atoms and transfer their kinetic energy to the atoms. This process is called moderation, and slows the neutrons down to what is called thermal energy, .025 eV, or about 4900 miles/hr. Depending on the mass of the moderating material, it may take from 10-2500 impacts to reduce the speed of a fast neutron from fission to thermal equillibrium ...
The problem of analyzing data from a multisphere neutron spectrometer to infer the energy spectrum of the incident neutrons is discussed. The main features of the code MAXED, a computer program developed to apply the maximum entropy principle to the deconvolution (unfolding) of multisphere neutron spectrometer data, are described, and the use of the code is illustrated with an example. A user`s guide for the code MAXED is included in an appendix. The code is available from the authors upon request.
The effect of ion cyclotron resonance heating (ICRH) on ((3)He)D plasmas at JET was studied with the time of flight optimized rate (TOFOR) spectrometer dedicated to 2.5 MeV dd neutron measurements. In internal transport barrier (ITB) plasma experiments with large (3)He concentrations (X((3)He),15%) an increase in neutron yield was observed after the ITB disappeared but with the auxiliary neutral beam injection and ICRH power still applied. The analysis of the TOFOR data revealed the formation of a high energy (fast) D population in this regime. The results were compared to other mode conversion experiments with similar X((3)He) but slightly different heating conditions. In this study we report on the high energy neutron tails originating from the fast D ions and their correlation with X((3)He) and discuss the light it can shed on ICRH-plasma power coupling mechanisms.. ...
Abstract: The key requirement for a portable store of natural gas is to maximize the amount of gas within the smallest possible space. The packing of methane (CH4) in a given storage medium at the highest possible density is, therefore, a highly desirable but challenging target. We report a microporous hydroxyl-decorated material, MFM-300(In) (MFM = Manchester Framework Material, replacing the NOTT designation), which displays a high volumetric uptake of 202 v/v at 298 K and 35 bar for CH4 and 488 v/v at 77 K and 20 bar for H2. Direct observation and quantification of the location, binding, and rotational modes of adsorbed CH4 and H2 molecules within this host have been achieved, using neutron diffraction and inelastic neutron scattering experiments, coupled with density functional theory (DFT) modeling. These complementary techniques reveal a very efficient packing of H2 and CH4 molecules within MFM-300(In), reminiscent of the condensed gas in pure component crystalline solids. We also report ...
Increasing attention is being devoted to the interaction of a new class of organic ionic liquids known as room-temperature ionic liquids (RTILs) with biomolecules, partly because of health and environment concerns, and, even more, for the prospect of exciting new applications in biomedicine, sensing and energy technologies. Here we focus on the interaction between RTILs and phospholipid bilayers that are well-accepted models for bio-membranes. We discuss how neutron scattering has been used to probe both the structure and the dynamics of these systems, and how its integration with molecular dynamics simulation has allowed the determination of the microscopic details of their interaction.. ...
The structure of liquid semiconductors, superionic conductors and glasses by neutron scattering, X-ray diffraction and extended X-ray absorption fine structure ...
Ensuring effective control instrument, development of new methods and improving the accuracy of geophysical instrumentation devices used in exploration of mineral resources is one of the important problems in the mining industry. This paper discusses current research and options for optimizing the electrical and structural parameters monitoring devices neutron yield borehole neutron generator for the respective systems of neutron-neutron logging, for which we have developed and successfully used diamond detectors. Further expansion of the applications of diamond materials in new areas of the economy, especially in instrumentation, will ensure a more rational and efficient use of natural resources. The results of the research staff monitor devices for monitoring the neutron yield borehole neutron generator systems for neutron-neutron logging including for replacement to the original diamond detectors domestic production. - investigation of the influence of environmental parameters on the downhole ...
The discovery of penicillin almost 90 years ago ushered in the age of modern antibiotics, but the growth of antibiotic resistance means bacterial infections like pneumonia and tuberculosis are becoming more difficult to treat.. Researchers at the US Department of Energys (DOEs) Oak Ridge National Laboratory (ORNL) are conducting a series of experiments at ORNLs Spallation Neutron Source (SNS) to make sense of this phenomenon. Using theMaNDi instrument, SNS beamline 11B, they hope to better understand how bacteria containing enzymes called beta-lactamases resist the beta-lactam class of antibiotics. Any antibiotic containing a beta-lactam ring made up of organic compounds falls under this category.. We are looking for answers on a fundamental science level, said MaNDi instrument scientist Leighton Coates. We have the machinery to explore these interactions using neutrons.. With neutrons, the team can observe firsthand how beta-lactamases break down drug compounds without damaging the ...
Jimmy Neutron: Boy Genius - In this fast moving, computer-animated fantasy, Paramount Pictures and Nickelodeon Movies team up once more to provide a fun, fascinating comedy-adventure for kids. Jimmy Neutron, a 10-year-old techno-genius, has all sorts of sci-fi techno-gadgets in his house and even makes contact with a hoard of aliens, called Yokians. But the aliens swoop down on his town of Retroville and abduct all the parents. Without parental supervision, the children go on a wild party spree, but soon come to regret it and wish their parents were back. So, with the technical inventiveness of Jimmy Neutron, the kids build some rudimentary space ships and are off to rescue their parents. They end up doing battle with the Yokians and their monstrous, wrathful pagan god.
- We investigate neutron-induced and photonuclear reactions to provide data relevant to basic science, nuclear astrophysics, and technology. At the nELBE photo-neutron source an intensive, continuous spectrum of 1011 neutrons per second is generated. Time of flight measurements allow to precisely determine reaction rates e.g. of inelastic neutron scattering and neutron induced fission. The γELBE bremsstrahlung source generates a photon spectrum with an end point energy of up to 18 MeV. Nuclear reactions and nuclear structure are studied by photon scattering and photoactivation, both in conjunction with high resolution γ spectroscopy.
E170 Terminology Relating to Radiation Measurements and Dosimetry. E265 Test Method for Measuring Reaction Rates and Fast-Neutron Fluences by Radioactivation of Sulfur-32. E693 Practice for Characterizing Neutron Exposures in Iron and Low Alloy Steels in Terms of Displacements Per Atom (DPA). E720 Guide for Selection and Use of Neutron Sensors for Determining Neutron Spectra Employed in Radiation-Hardness Testing of Electronics. E721 Guide for Determining Neutron Energy Spectra from Neutron Sensors for Radiation-Hardness Testing of Electronics. E844 Guide for Sensor Set Design and Irradiation for Reactor Surveillance. E944 Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance. ...
TY - JOUR. T1 - Probing the dynamics and structure of confined benzene in MCM-41 based catalysts. AU - Dervin, Daniel. AU - OMalley, Alexander. AU - Falkowska, Marta. AU - Chansai, Sarayute. AU - Silverwood, Ian. AU - Hardacre, Christopher. AU - Catlow, C. Richard A. PY - 2020/5/11. Y1 - 2020/5/11. N2 - A combination of Molecular Dynamics (MD) simulations and Quasielastic Neutron Scattering (QENS) experiments has been used to investigate the dynamics and structure of benzene in MCM-41 based catalysts. QENS experiments of benzene as both an unconfined liquid and confined in the catalyst Pt/MCM-41 find that the mobility of benzene decreases upon confinement as shown by the decreased diffusion coefficients. Complementary MD simulations on benzene in MCM-41 show agreement with the QENS experiments when using a novel fully flexible model of MCM-41. Structural information from the MD simulations show that benzene in MCM-41 has a significantly different structure from that of the bulk liquid; with ...
When young female A × C rats were given 9.6 rads of 0.43-MeV neutrons, 32 of 33 survived a 50-week follow-up period, 2 rats developed a total of 3 mammary adenocarcinomas, and 3 rats developed a total of 4 mammary fibroadenomas. For 25 rats implanted with a 20-mg pellet containing 5 mg diethylstilbestrol and 15 mg cholesterol, average survival was 284 days; 22 rats developed a total of 182 mammary adenocarcinomas, and 21 rats developed a pituitary tumor. When diethylstilbestrol was given 2 days before neutron radiation to 35 rats, the average survival was 239 days; 32 rats developed a total of 842 mammary adenocarcinomas, 1 rat developed a single mammary fibroadenoma, and 34 rats developed a pituitary tumor. All of the 31 control rats survived the 50-week study period, and none developed tumors. Twenty-one of the rats that received both diethylstilbestrol and neutron radiation and 1 rat that received only diethylstilbestrol exhibited a multiple mammary adenocarcinoma response with a range of 18 ...
Researchers from the Paul Scherrer Institute (PSI) in Switzerland, Romain Sibille and Nicolas Gauthier, are studying a fascinating sample using neutrons at the Department of Energys (DOEs) Spallation Neutron Source (SNS) at Oak Ridge National Laboratory.. Their goal is to create an observable case of quantum spin ice, a bizarre magnetic state found in a special class of materials that could lead to advances in quantum computing technologies.. We study mostly oxides, which include rare-earth magnetic elements, said Sibille. Right now, we are studying a sample thats a candidate for a magnetic phase that, so far, has been hard to observe: quantum spin ice. We hope to find this and demonstrate it with the new capabilities here at SNSs HYSPEC instrument using polarization and the supermirror from PSI.. In 2015, HYSPEC, SNS beamline 14B, received a new wide-angle polarizing supermirror array built by scientists and engineers at PSI. The new supermirror enables users to perform ...
Abstract: Secondary neutrons are a main source of stray and leakage radiation outside treatment fields in proton radiotherapy and therefore, pose a risk to patients for the development of second cancers. In addition, the nozzle components of the proton therapy unit remain hot some time after the treatment and induce time-dependent decays from mixed neutron/gamma-ray fields, which potentially put radiation therapists at risk for excessive cumulative dose exposures post treatment. The accuracy of the nuclear physics model used to predict stray neutron fields in proton radiotherapy is not clearly understood. The Tool for Particle Simulation (TOPAS) was used to calculate the therapeutic absorbed dose and neutron spectral fluence from a proton treatment unit using three nuclear physics models: the Bertini model, the Binary Cascade model and the INCL4/ABLA model. TOPAS is based on the platform of the Geant4 Monte Carlo Toolkit (version 9.6). The purpose of this research is to compare and quantify ...
Liquid neutron absorbers are also used in rapid shutdown systems for light water reactors. Following SCRAM, if the reactor (or section(s) thereof) are not below the shutdown margin (they are still critical), the operators can inject solutions containing neutron poisons directly into the reactor coolant. Neutron poisons are water-based solutions that contain chemicals that absorb neutrons, such as common household borax, sodium polyborate, boric acid, or gadolinium nitrate, causing a decrease in neutron multiplication, and thus shutting down the reactor without use of the control rods. In the PWR, these neutron absorbing solutions are stored in pressurized tanks (called accumulators) that are attached to the primary coolant system via valves; a varying level of neutron absorbent is kept within the primary coolant at all times, and is increased using the accumulators in the event of a failure of all of the control rods to insert, which will promptly bring the reactor below the shutdown margin. In ...
A research team including Georgia Institute of Technology professor Martin Mourigal used neutron scattering at Oak Ridge National Laboratory to study copper elpasolite, a mineral that can be driven to an exotic magnetic state when subjected to very low temperatures and a high magnetic field.. A better understanding of the minerals magnetic moments and the associated quantum coherence effects could lead to new applications in spintronic devices and quantum computing technologies.. Studying the behavior of magnetic materials in extreme conditions such as very low temperatures and high magnetic fields is important to obtain a better fundamental understanding of quantum materials, and to write the basic dictionary relating their microscopic structure to human-scale properties, Mourigal said.. To reveal the materials magnetic structure, the team used the Neutron Powder Diffractometer and Polarized Triple Axis Spectrometer instruments at ORNLs High Flux Isotope Reactor-a DOE Office of Science ...
Professor Thomas P. Russell, polymer science and engineering, was recently honored by the Neutron Scattering Society of America with its highest honor, the Clifford G. Shull Prize in Neutron Science.
The very neutron-rich oxygen isotopes 25O and 26O are investigated experimentally and theoretically. The unbound states are populated in an experiment performed at the R3B-LAND setup at GSI via proton-knockout reactions from 26F and 27F at relativistic energies around 442 and 414 MeV/nucleon, respectively. From the kinematically complete measurement of the decay into 24O plus one or two neutrons, the 25O ground-state energy and width are determined, and upper limits for the 26O ground-state energy and lifetime are extracted. In addition, the results provide indications for an excited state in 26O at around 4 MeV. The experimental findings are compared to theoretical shell-model calculations based on chiral two- and three-nucleon (3N) forces, including for the first time residual 3N forces, which are shown to be amplified as valence neutrons are added ...
Uranyl fluoride (UO2F2) is a hygroscopic powder resulting from the hydrolysis of uranium hexafluoride (UF6). Crystal hydrates of the form UO2F2*x(H2O) have previously been identified with X-ray and neutron scattering, but phase transitions between different crystal hydrate structures have not been directly observed. In this work, we present a combined experimental and theoretical approach to determining crystal structures and vibrational modes. We use inelastic neutron scattering to probe vibrational frequencies of powder samples of anhydrous uranyl fluoride (x = 0, anh-UO2F2), and the most stable crystal hydrate (x = 0.4, partially hydrated (ph-UO2F2)). Combined with density functional theory (DFT), we identify and differentiate crystalline phonons and water-coupled phonon modes. Significant shifts in water O-H stretching frequencies are observed as well as lower-energy water librational modes due to water-crystal interactions. Finally, we use temperature-dependent Raman scattering with a ...
For a discussion of the problem see Refs. 25, 35, and 74. [2] PURIFICATIONOF Na +,K+-ATPase 29 [2] Purification of N a + , K + - A T P a s e : E n z y m e Sources, Preparative Problems, and Preparation from Mammalian Kidney B y PETER L E T H J~RGENSEN Introduction Purification of Na+,K+-ATPase to homogeneity requires starting material from tissues with exceptionally large capacities for active Na ÷ transport like the outer renal medulla in mammalian kidney, 1-4 rectal glands of dogfish,5,6 eel electroplax,7,8 and salt glands of ducks in which Na+,K+-ATPase can be induced by salt treatment. 53 Sedimentation velocity analysis of mammalian kidney enzyme dissolved in C12E8 gives a molecular weight of 170,00061 and low-angle neutron scattering analysis of mammalian kidney enzyme dissolved in Brij gives a molecular weight of 310,000. 62 Radiation inactivation measurements on partly purified membrane preparations give a molecular weight for Na ÷,K+-ATPase from red blood cells of 300,00063 and ...
Fundamental studies into photovoltaic materials, namely copper indium gallium diselenide, have been undertaken at Salford since the 1970s (e.g. for solar energy applications). A particular research focus is the development of new hydrogen storage materials (for mobile applications). Related work includes: studies of fuel transport systems, magnetic phase transitions induced by hydrogen, and hydrogen-bonded systems (Raman spectroscopy, x-ray crystallography and nonlinear optics). Various environmentally-friendly technologies, applications and fuels are developed, and a range of nuclear fission and fusion energy materials are investigated - a current project is part of a national effort to understand the effects of neutron irradiation on nuclear graphites. Our contribution involves the use of coherent inelastic neutron scattering to investigate the dynamics of radiation-induced defects. ...
High-temperature single-crystal measurements of metamict zircon were performed up to 2000 K and the recrystallization was monitored using the width and intensity of selected peaks. Full data sets were collected at room temperature, 1573 and 1823 K. The changes in the probability density function (p.d.f.) of the O atoms revealed important features of the recrystallization. The measurements were done in air using a mirror furnace and performed on the D19 four-circle diffractometer at the ILL equipped with a vertically curved two-dimensional position-sensitive detector. ...
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We investigate the structural changes to lipid membrane that ensue from the addition of aliphatic alcohols with various alkyl tail lengths. Small angle neutron diffraction from flat lipid bilayers that are hydrated through water vapor has been employed to eliminate possible artefacts of the membrane curvature and the alcohols membrane-water partitioning. We have observed clear changes to membrane structure in both transversal and lateral directions. Most importantly, our results suggest the alteration of the membrane-water interface. The water encroachment has shifted in the way that alcohol loaded bilayers absorbed more water molecules when compared to the neat lipid bilayers. The experimental results have been corroborated by molecular dynamics simulations to reveal further details. Namely, the order parameter profiles have been fruitful in correlating the mechanical model of structural changes to the effect of anesthesia.