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 ...
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 ...
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 ...
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 ...
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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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 ...
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. ...
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, ...
Continuing his discovery of positrino and electrino, postulating, as absolute symmetry, the tetrahedroncubic base of the world - [ASTC] - the representation of a proton and a neutron, a neutron star. The essence of the doctrine of the novelty of the human outlook on nature for humanity in the light of ASTC is exemplified in the abstract: the example of a proton and neutron device, a neutron star. An analogy is suggested, as a lyrical digression, by association with a vine with bunches of grapes, using the example of a quark device. Lyrical digressions in the illustration of the device of a neutron and a proton, quarks lead us to the ensembles of spaces of a certain number of electrino (E-1 \ 3) and spaces of a certain number of positrino (E + 1 \ 3) in their internal arrangement. ...
A neutron star is a very small and dense star made almost completely of neutrons. They are small stars with a radius of about 11-11.5 kilometres. They have a mass of about twice that of the Sun. They are the smallest and densest stars known to exist in the Universe.[1] They are what is left of a huge star which exploded as a supernova.. The density of the star is like that of the nucleus of an atom. They have strong magnetic fields, between 108 and 1015 times as strong as that of Earth. The gravitational field at the neutron stars surface is about 2×1011 times stronger than on Earth.. To imagine how dense a neutron star is, take all of the mass of our sun (which has a diameter of 1,392,000 kilometres (865,000 mi)) and push it down into a size that would fit into a ball with a 19 kilometres (12 mi) diameter. Another way to understand the density is this: one teaspoon of matter from the neutron star would weigh 6 billion tons.. Neutron stars spin very fast, from 0.001 second up to 30 seconds to ...
Among the many radiation hazards of manned spaceflight is the potential exposure of crew members to neutrons. These neutrons are produced from several sources: from the terrestrial albedo and as secondary particles produced by the interaction of cosmic rays, solar protons and trapped protons with the material of the spacecraft. Recently, neutrons have also been observed originating in solar flares, at the solar surface. Theoretical estimates and experimental measurements of the neutron fluxes inside manned spacecraft in near-Earth orbit are reviewed and discussed. The anticipated neutron fluxes and their resulting dose-equivalents, as a function of shielding depth for exploration class missions, are presented and discussed ...
Knowing a neutron stars equation of state allows physicists to determine what kind of matter can exist within that star. Scientists need to understand such exotic matter to test theories describing the fundamental nature of matter and energy, and the strength of nuclear interactions. "We would really like to get our hands on the stuff at the center of a neutron star," said Strohmayer. "But since we cant do that, this is about the next best thing. A neutron star is a cosmic laboratory and provides the only opportunity to see the effects of matter compressed to such a degree." A neutron star is the core remnant of a star once bigger than the sun. The interior contains matter under forces that perhaps existed at the moment of the Big Bang but which cannot be duplicated on Earth. In this system, gas from a "normal" companion star, attracted by gravity, plunges onto the neutron star. This triggers thermonuclear explosions on the neutron star surface that illuminate the region. Such bursts often ...
Some materials with the fluorite structures show a pronounced specific heat anomaly well below their melting temperature. This anomaly is a consequence of lattice disorder and is associated with the onset of fast-ion conduction. This paper presents the results of a series of experiments in which the coherent diffuse quasielastic neutron scattering from single crystals of three such fluorite compounds PbF2, SrCl2 and CaF2, was investigated. The diffuse scattering intensity, and its energy width, increases with temperature into the fast-ion phase, and when integrated over energy transfer the intensity exhibits a characteristic variation with scattering vector, falling on an anisotropic shell in reciprocal space and peaking in certain directions. The diffuse intensity indicates that dynamic correlations exist between the defective anions in the fast-ion-phase. A model of short-lived clusters comprising anion Frenkel interstitials, anion vacancies and relaxed anions has been developed which ...
This is one of the reasons that scientists have been working hard to improve and enhance CFPs for many years. It has been a challenging task and at one point there was a 13-year gap between the availability of the first useable CFP and the discovery of a variant with almost perfect fluorescence efficiency.. In order to be useful as biomarkers, CFPs must emit sufficient fluorescent light to be easily and reliably detectable. The fluorescence efficiency (or quantum yield) must be as high as possible and it can be affected by the molecular dynamics of proteins, such as the flexibility or rigidity of the protein core.. The researchers used a technique at ILL called incoherent neutron scattering to look at the molecular dynamics of five different CFPs. By firing beams of neutrons at the CFPs and carefully analysing the pattern of scattered neutrons, scientists were able to observe how atoms and molecules within the proteins vibrate, rotate and move, revealing crucial information about their dynamic ...
Experimental molecular dynamics studies in biological systems are attracting growing interest. Single-particle neutron spectroscopy has revealed itself as an extremely rich technique for dynamics measurements on living cells. The method provides a unique combination of atomic length-scale resolution and subnanosecond time-scale resolution. Thermal neutrons provide wavelengths of a few angströms that correspond to interatomic distances, and energies of a few millielectron volts that correspond to thermal fluctuations in biological samples. In these conditions and because of the absence of charge of the neutron, the neutron-matter interaction is non-destructive. Single-particle neutron spectroscopy provides a direct measurement of atomic and molecular motions on the ps-ns time scale.. The scattering signal is dominated by the scattering of hydrogen nuclei, which have an incoherent cross section one order of magnitude larger than the cross section of any other nucleus or isotope, including ...
After the pinhole is a rotating drum with four positions (4 in Fig. 2). Three of the positions have holes for additional collimation or filters if needed. These collimators are currently 1 cm, 2 cm, and open collimation. The fourth position is used to block the beam when the facility is not in use. Neutrons and gamma rays scattered out of the beam must be stopped to prevent them from becoming a hazard to personnel or to other scientific neutron data collection experiments in the CNR. The shielding used to do this is a steel encased mixture of wax and steel shot. The high energy neutrons are turned into thermal neutrons in the wax and stopped be the material and the gammas are absorbed by the steel shot (see 5 in Fig. 2). The beam that is now collimated passes out of the drum and into a sealed, evacuated aluminum flight tube (6 in Fig. 2). The flight tube ends right before the sample position (7 in Fig. 2), which is open to air. At the sample position an object to be radiographed sits on a ...
A neutron collides elastically with a helium nucleus (at rest initially) whose mass is four times that of the neutron. The helium nucleus is observed to rebound at an angle θ2 = 41° from the neutrons initial direction. The neutrons initial speed is 6.2 x10^5 m/s. Determine the angle at which the neutron rebounds, θ1, measured from its initial direction ...
Wladimir, great theory, many thanks for the many hours of intellectual labor you have put into this, be proud of your great mind!. Some questions, the quantum spin of the electron is due to its helical spiral movement, and this spin is lost in the low orbit within the neutron, so the electron quantum sping disappears (spin fusion). Secondly, the neutron magnetic dipole moment is also dependent on this helical spiral movement of the electron. Does this mean that the spiral diameter is more or less that of the neutron diameter, such that the usual helical movement of a bound electron cannot exist anymore in the very small orbit within a neutron? In other words, is the spin movement converted into an orbit movement, during the collapse of a proton and electron into a neutron?. If quantum spin can be converted into orbital movement, do we still need a neutrino for having "spin conservation"? You did not mention the neutrino once.. I also like very much your suggestion about the non-validity of the ...
Pulsars, in particular, millisecond and binary pulsars offer new and unique tests of physics. The explosive birth of neutron stars and coalescence of binary neutron stars are prime targets for planned gravitational wave interferometers. All these applications require a thorough understanding of the statistics of pulsars to reliably estimate detection frequencies and thresholds. There are many aspects of the origin and evolution of neutron stars that benefit from an appreciation of pulsar phenomenology and statistics. Theoretical understanding of the magnetic field evolution of neutron stars is, at the present, poor. Statistical studies continue to play an important role in guiding us empirically in this area. The shortest spin period of a neutron star directly constrains the equation of state of dense matter. The limitations of current millisecond pulsar searches in this regard is thoroughly reviewed. The prospects and problems of searchers for pulsars with periods below a millisecond are ...