Neutron Reflection

, E-mail hans.te.nijenhuis@ panalytical.com Recent interest in nanomaterials has increased the need to analyze structures on a local (nano) scale. However, the atomic structures of nanoparticles and nanostructured materials are not accessible by conventional methods used to study crystalline materials, because of the short ordering range in these materials. One of the most promising techniques to study nanostructures using X-ray diffraction is total scattering pair distribution function (PDF) analysis. This technique is successfully applied in a number of application areas in materials science and technology. The PDF analysis technique makes use of high quality, high energy X-ray scattering data, usually obtained at synchrotron facilities, available in several national and international research centers around the world. Despite the advantages and data quality that measurements at synchrotron beam lines offer to the researcher, in practice it can be difficult and time-consuming to get access to the facilities required. In order to be prepared as good as possible and to make optimal use of the valuable experiment time offered, it is highly desirable to perform selective measurements on candidate samples in the own research laboratory. New developments in XRD technology have been directed towards the possibility of performing nanocrystallography experiments on a standard laboratory X-ray diffraction system. In this presentation we will report on the possibilities and limitations of the use of high-energy X-rays on a homelab system.

Self-Indication Neutron Resonance Densitometry (SINRD) is a passive non-destructive method that is being investigated to quantify the 239 Pu content in a spent fuel assembly. The technique relies on the energy dependence of total cross sections for neutron induced reaction. The cross sections show resonance structures that can be used to quantify the presence of materials in objects, e.g. the total cross-section of 239 Pu shows a strong resonance close to 0.3 eV. This resonance will cause a reduction of the number of neutrons emitted from spent fuel when 239 Pu is present. Hence such a reduction can be used to quantify the amount of 239 Pu present in the fuel. A neutron detector with a high sensitivity to neutrons in this energy region is used to enhance the sensitivity to 239 Pu. This principle is similar to self-indication cross section measurements. An appropriate detector can be realized by surrounding a 239 Pu-loaded fission chamber with appropriate neutron absorbing material. In this contribution experiments performed at the GELINA time-of-flight facility of the JRC at Geel (Belgium) to validate the simulations are discussed. The results confirm that the strongest sensitivity to the target material was achieved with the self-indication technique, highlighting the importance of using a 239 Pu fission chamber for the SINRD measurements.

Self-Indication Neutron Resonance Densitometry (SINRD) is a passive non-destructive method that is being investigated to quantify the 239 Pu content in a spent fuel assembly. The technique relies on the energy dependence of total cross sections for neutron induced reaction. The cross sections show resonance structures that can be used to quantify the presence of materials in objects, e.g. the total cross-section of 239 Pu shows a strong resonance close to 0.3 eV. This resonance will cause a reduction of the number of neutrons emitted from spent fuel when 239 Pu is present. Hence such a reduction can be used to quantify the amount of 239 Pu present in the fuel. A neutron detector with a high sensitivity to neutrons in this energy region is used to enhance the sensitivity to 239 Pu. This principle is similar to self-indication cross section measurements. An appropriate detector can be realized by surrounding a 239 Pu-loaded fission chamber with appropriate neutron absorbing material. In this contribution experiments performed at the GELINA time-of-flight facility of the JRC at Geel (Belgium) to validate the simulations are discussed. The results confirm that the strongest sensitivity to the target material was achieved with the self-indication technique, highlighting the importance of using a 239 Pu fission chamber for the SINRD measurements.

The new backscattering spectrometer RSSM for the FRM-II reactor uses all possibilities to optimize this type of spectrometer. In its high-intensity version it uses unpolished Si(111) crystals. The good energy resolution of δE ≤ 0.9 µeV is achieved by staying as closely as possible at a Bragg angle of 90 • not only at the Doppler monochromator in the primary spectrometer but also at the analyzer system of the secondary spectrometer. The large solid angle of the analyzer system compensates the low intensity which is a result of the good energy resolution.

Organic photovoltaic (OPV) active layers made by spin-coating a solution comprising poly(3hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles have been shown to adopt a non-uniform concentration profile across the thin film dimension. This inhomogeneous distribution can reduce the efficiency of the device. In the present work a new process, gas expanded polymer (GXP) annealing, is applied to P3HT/PCBM thin film blends,

Coupled electron-photon-neutron transport calculations were performed with the Monte Carlo code MCNP4C3 to model the GELINA neutron target. Our calculations were compared with measurements of the direct and moderated flux distributions and agreement was achieved within 20%. Further, the present simulations were compared with the resolution functions established earlier with a dedicated program and with measured data for 56 Fe. Here too, the agreement is excellent. New IAEA photonuclear libraries were implemented to perform these calculations. The simulations crucially rely on the new MCNP4C3 photonuclear capabilities and are made efficient by using the variance reduction and TALLYX features.

We describe the Compact Accelerator-based Neutron Source SONATE which we are aiming for to replace the closed Orphée reactor at Saclay, France. The SONATE source would serve an instrumental suite of about 10 instruments. The instruments would be split into low resolution instruments and higher resolution instruments. Our reference design is based on a proton accelerator operating at an energy in the range 20-30 MeV. The accelerator would serve 2 target stations. The first one operating at 20Hz with 2ms long pulses serving low resolution instruments (SANS, reflectivity, imaging, spin-echo) and the second one operating at 100Hz, 200μs long pulses serving higher resolution instruments (powder diffraction, Direct Time-of-flight spectroscopy, Indirect geometry spectroscopy). The 2 operation modes would be interlaced. The peak current on the target is aimed at 100 mA with an average power on the target on the order of 50-80 kW. Numerical Monte-Carlo simulations show that we may expect ins...

Bulk heterojunction organic solar cells based on blends of a conjugated polymer (donor) and a fullerene derivative (acceptor) have attracted considerable attention due to their rapidly increasing effi ciencies and their potential as a low-cost, printable, and fl exible renewable energy source. [ 1-3 ] Until recently, polymer:fullerene blends were thought to phase separate into pure polymer and pure fullerene domains. However, recent studies using a variety of techniques-including small-angle neutron scattering (SANS), [ 4 , 5 ] scanning transmission X-ray microscopy (STXM), [ 6 ] dynamic secondary ion mass spectrometry (DSIMS), [ 5-7 ] energy-fi ltered transmission electron microscopy (EFTEM), [ 8 , 9 ] photoluminescence, [ 10-15 ] and X-ray scattering [ 8 , 12-16 ]-have altered this traditional view. For instance, studies of blends of the semi-crystalline polymer poly(3-hexylthiophene) (P3HT) with the fullerene derivative phenyl-C 61-butyric acid methyl ester (PCBM-C60) have demonstrated the existence of pure crystalline P3HT, pure PCBM-C60, and molecularly mixed, amorphous P3HT:PCBM-C60 domains. [ 4-9 ] Furthermore, molecular mixing has been demonstrated in amorphous MDMO-PPV:PCBM-C60 blends. [ 11 , 17-19 ] Polymer:fullerene molecular mixing can also occur in semicrystalline domains via fullerene intercalation between the polymer side chains to form polymer:fullerene bimolecular crystals (Figure 1). [ 12-16 , 20-22 ] The concept of intermixed donor-acceptor interfaces, which exist in intercalated polymer:fullerene blends as well as molecularly mixed amorphous blends, challenges to some extent the notions regarding the operation of organic solar cells, as it is generally hypothesized that excitons originating in a pure phase diffuse to a polymer-fullerene (donor-acceptor) interface and split into separated charges (that are then extracted from the device via migration through the pure phases). That intermixing occurs in many polymer:fullerene blends should impact solar-cell operation, as the very nature of the donor-acceptor interface changes. For example, molecular mixing due to intercalation in semicrystalline blends or miscibility in amorphous

Bulk heterojunction (BHJ) solar cells based on a blend of an electron donor polymer (such as regioregular poly(3-hexylthiophene) (P3HT) or poly(2-methoxy-5-(3 0 ,7 0-dimethyloxy)-p-phylene vinylene) (MDMO-PPV)) and an electron accepting fullerene (either phenyl-c61butyric acid methyl ester (PC [61] BM) or phenyl-c71-butyric acid methyl ester (PC [71] BM)) have received considerable attention recently due to a reported power conversion efficiency around 5% along with the promise of low-cost production. [1-6] The performance of BHJs is heavily influenced by the interpenetrating nanostructure formed by the two semiconductors because exciton dissociation, recombination and charge transport are all affected by the size of the phases, the nature of the interface and molecular packing. The specific nanostructure morphology is a result of the interplay between the thermodynamics of the blend, which arise from the nature of the intermolecular bonds and determine the equilibrium state, and the kinetics of film formation, which determine the approach to equilibrium. Despite much work in this area, most BHJ design is highly empirical. A variety of polymer:fullerene BHJ solar cells have been explored and it has been found that some systems optimize with a blend ratio around 1:1 by weight, but most optimize closer to 1:4 by weight. Little is known about what material properties are responsible for determining the optimal blend ratio. It is known that the optimal 1:4 MDMO-PPV:PC [61] BM system contains PC [61] BM domains surrounded by a phase that is composed of the polymer and the fullerene intimately mixed at the molecular level. [6] In P3HT:PC [61] BM solar cells, the materials are thought to separate

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Compact Neutron Sources for Neutron Scattering Frédéric Ott

The channeling of neutrons in a three-layer planar waveguide with a neutron-optical potential well is studied. Neutrons incident on a sample surface, which propagate in a middle layer and escape from the waveguide end in the form of a narrow divergent beam, are detected. The decay parameter of a neutron wave inside the waveguide is measured as a function of the potential well depth. Experimental results are compared with a theory.

The present work attempts to increase the benefit of using calcium fluoride based slag, which considers as waste material after remelting of advanced steel by an electro slag remelting (ESR) process, as one of innovative material for nuclear shielding applications. This work differentiates between the neutron shielding properties of different types of steel slag waste, types of stainless steel and ordinary concrete. The total and partial neutron interactions have been done in the energy range of 10 −5 eV-20 MeV using Monte Carlo program. The dependence of total and partial neutron macroscopic cross sections (MaCSs) on incident neutron energy and elemental composition has been evaluated. Besides, the total and partial microscopic cross sections (MiCSs) were determined via the total and partial MaCSs. It was found that the rutile has higher total MaCSs and MiCSs than the other investigated materials. This study should be useful for potential application of these materials in the field of nuclear radiation for choice of neutron shielding materials.

In soft matter small angle neutron scattering (SANS) studies at large Q values, incoherent scattering becomes the dominant signal. In the Q-range of interest to this work, from 0.2 Å −1 to about 1.0 Å −1 , the coherent scattering from the typical protein or polymer in a D 2 O buffer solution inevitably drops one to two orders of magnitude or more below the total scattering. Even after careful and accurate subtraction of the measured D 2 O buffer scattering, the remaining corrected, i.e. sample-only, signal will still be dominated by diffuse incoherent scattering from hydrogen in the sample itself. This is the exact region of interest when one wishes to probe the structural changes in "living" proteins caused by interactions and motions related to function. To further complicate the problem, there is strong motivation to measure this Q-regime at very low concentrations because it has been shown with wide angle X-ray scattering that proteins can undergo concentration-dependent structural changes that rapidly increase below concentrations of about 5% [1] motivating the study of protein solutions at ever lower concentrations. In this case the signal from the protein will inevitably become much less than the scattering of the D 2 O buffer solution it is contained in. Polarization analysis offers the opportunity to separate the weak coherent signal from the larger incoherent signal and perhaps enable measurements under the conditions described above. This paper will address the issues associated with the correct separation of coherent and incoherent scattering for soft matter samples. We have performed tests measurements on KWS2 which show the viability of the method on a protonated α-lactalbumin solution at 2.5% (1 mm thick) and 0.25% (2 mm thick) concentrations in a D 2 O buffer solution. Additionally describe a the method of implementation using 3 He spin filters, some practical considerations, and future plans for a dedicated device at the JCNS.

An overview is provided of the 15 neutron beam instruments making up the initial instrument suite of the European Spallation Source (ESS), and being made available to the neutron user community. The ESS neutron source consists of a high-power accelerator and target station, providing a unique long-pulse time structure of slow neutrons. The design considerations behind the time structure, moderator geometry and instrument layout are presented. The 15-instrument suite consists of two small-angle instruments, two reflectometers, an imaging beamline, two single-crystal diffractometers; one for macromolecular crystallography and one for magnetism, two powder diffractometers, and an engineering diffractometer, as well as an array of five inelastic instruments comprising two chopper spectrometers, an inverse-geometry single-crystal excitations spectrometer, an instrument for vibrational spectroscopy and a high-resolution backscattering spectrometer. The conceptual design, performance and scientific drivers of each of these instruments are described. All of the instruments are designed to provide breakthrough new scientific capability, not currently available at existing facilities, building on the inherent strengths of the ESS long-pulse neutron source of high flux, flexible resolution and large bandwidth. Each of them is predicted to provide world-leading performance at an accelerator power of 2 MW. This technical capability translates into a very broad range of scientific capabilities. The composition of the instrument suite has been chosen to maximise the breadth and depth of the scientific impact of the early years of the ESS, and provide a solid base for completion and further expansion of the facility.

Neutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed.

This paper gives an overview of weak aggregation due to long-range molecular forces beyond the first neighbor. Such subtle self-assemblies are an important part of modern colloidal chemistry and concern organic molecules as well as inorganic electrolytes and hybrid aggregates. Diverse aspects of such colloidal aggregations, as described in this special issue, can be characterized by the effective free energy per molecule involved. We discuss here expectations about emerging knowledge in this field and predictive modeling of inorganic as well as organic colloids and hybrid aggregates. Some still open questions are also given. State of the art Weak aggregation is an often encountered phenomenon that is related to very small free energies of formation, typically below 1 k B T per molecule, which corresponds to 2.5 kJ/mole. Such labile structures occur in "Ouzo" emulsions and "pre-Ouzo" microemulsions, stabilized by impurities or antagonistic salts or near a phase boundary, they are also found in flexible membranes and liquidliquid interfaces, where capillary interactions are relevant, and they can even lead to structured "interphases".

Le but de cette etude est de developper un modele quantitatif pour l’interaction et la propagation des neutrons de faible energie dans les milieux nanodisperses (en utilisant la nanopoudre de diamant comme exemple), qui prend en compte l’influence de la densite moyenne nanodispersee sur les processus de la propagation et la diffusion des neutrons a basse energie, et les informations sur la structure d'une nanopoudre de diamant.L'urgence du probleme a resoudre est due au manque d'informations sur la completude des concepts des systemes etudies, sur les mecanismes d'interaction des neutrons de basse energie avec les materiaux nanostructures, sur les caracteristiques des proprietes de la structure des nanodisperses. medias, sur l'evolution des systemes nanodisperses sous l'influence des rayonnements. Le developpement du modele quantitatif propose est necessaire pour l'evaluation qualitative et l'interpretation de diverses donnees experimentales. L’elabor...

I dedicate my dissertation to my father Mr. Dixit M Shrestha, mother Yamuna Shrestha, who are no more with us to celebrate my success and share the happiness, my brothers Mr. Ramesh M Shrestha, Mr. Girish M Shrestha, sister Rita Shrestha, my sisters-in-law who always encouraged and supported me all these years. To my wife Sabina Maskey, for her support, love, understanding and being with me all time and to our four year old son Unnabh M Shrestha whose love kept me strong at all hard times. v ACKNOWLEDGMENTS First and foremost I would like to express my sincere graduate to my research advisor Dr. Dvora Perahia for her continuous support, guidance, motivation and understanding during my graduate studies. Without her support and encouragement, I would not be here today. I would like to acknowledge my committee members; Dr. Brain

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

Nanomaterials can intensively scatter and/or reflect radiation. Such processes and materials are of theoretical and practical interest. Here, we study the quasi-specular reflections (QSRs) of cold neutrons (CNs) and the reflections of very cold neutrons (VCNs) from nanodiamond (ND) powders. The fluorination of ND increased its efficiency by removing/replacing hydrogen, which is otherwise the dominant cause of neutron loss due to incoherent scattering. The probability of the diffuse reflection of VCNs increased for certain neutron wavelengths by using appropriate ND sizes. Based on model concepts of the interaction of CNs with ND, and in reference to our previous work, we assume that the angular distribution of quasi-specularly reflected CNs is narrower, and that the probability of QSRs of longer wavelength neutrons increases if we increase the characteristic sizes of NDs compared to standard detonation nanodiamonds (DNDs). However, the probability of QSRs of CNs with wavelengths bel...

Linac yang dioperasikan di atas 10 MV akan menghasilkan radiasi sekunder berupa emisi neutron yang berasal dari reaksi energi foton tinggi menumbuk material penyusun linac seperti target, kolimator dan filter. Radiasi sekunder ini akan menaikkan resiko kanker sekunder pada pasien akibat bertambahnya dosis radiasi yang diterima. Studi ini mengevaluasi fluks neutron termal spasial pada ruangan Linac yang dioperasikan 15 MV menggunakan metode aktivasi foil. Sebanyak 14 foil 115 In ditempatkan tersebar di dalam ruangan treatment yang terpapar pesawat linac 15 MV selama 1 menit. Hasil menunjukkan fluks tertinggi terdapat di sekitar isocenter sebesar , × • • Dengan nilai fluks tersebut dosis tambahan akibat neutron sebesar 0,04 Sv/menit.Nilai fluks menurun seiring bertambahnya jarak dari sumber berkas.Terkait dengan upaya proteksi radiasi untuk pekerja radiasi, adanya kontribusi dosis yang berasal dari neutron perlu ditindak lanjuti dengan menambah shielding pada pintu.

This paper gives an overview of weak aggregation due to long-range molecular forces beyond the first neighbor. Such subtle self-assemblies are an important part of modern colloidal chemistry and concern organic molecules as well as inorganic electrolytes and hybrid aggregates. Diverse aspects of such colloidal aggregations, as described in this special issue, can be characterized by the effective free energy per molecule involved. We discuss here expectations about emerging knowledge in this field and predictive modeling of inorganic as well as organic colloids and hybrid aggregates. Some still open questions are also given. State of the art Weak aggregation is an often encountered phenomenon that is related to very small free energies of formation, typically below 1 k B T per molecule, which corresponds to 2.5 kJ/mole. Such labile structures occur in "Ouzo" emulsions and "pre-Ouzo" microemulsions, stabilized by impurities or antagonistic salts or near a phase boundary, they are also found in flexible membranes and liquidliquid interfaces, where capillary interactions are relevant, and they can even lead to structured "interphases".

A polarized 3 He neutron-spin filter was used to analyze polarized neutrons reflected from a 1000-Å-thick Fe film immersed in a magnetic field. The spin filter analyzed both the specularly reflected component and the offspecular component caused by the phenomenon of Zeeman splitting of surface-scattered neutrons observed by Felcher et al. and investigated in more detail in subsequent experiments. The sample of polarized 3 He was polarized by metastabilityexchange optical pumping and compressed into a glass cell at the Indiana University Cyclotron Facility. The polarized gas was transported by car in a battery-powered solenoid holding field to the neutron reflectometry instrument POSY I at the Intense Pulsed Neutron Source at Argonne National Laboratory. Using the large solid angle of the polarized 3 He spin filter, we were able to simultaneously analyze both components to the scattering and verify (as expected) that the polarization of the specular component was unchanged upon reflection and that the polarization of the off-specular component was reversed. To our knowledge this work represents the second experiment to employ a polarized 3 He neutron-spin filter in polarized neutron reflectometry.

It is shown theoretically that neutrons transmitted along the axis of a helical magnetic structure, such as Dy or Ho, undergo rotation of the direction of polarisation, proportional to the thickness. Calculations for a simplified model indicate values of order 300 deg/mm. This value is considerably enhanced near a magnetic Bragg reflect. ion.

We describe refraction of neutrons through a magnetic prism which is exposed to an oscillating magnetic field. We show that an incident unpolarized neutron beam can be split in eight emerging beams which are spatially separated. Their intensity, wave vector values, and kinetic energy are treated analytically and numerically. We also show that the wavelength of neutron beams can be varied continuously by means of oscillating magnetic fields, which can also be considered as an inelastic interaction process.

A characterisation of cylindrical samples by Neutron Resonance Transmission Analysis (NRTA) at the GELINA facility of JRC Geel (Belgium) is presented. The samples were designed and produced for reactivity worth measurements in the MINERVE reactor of CEA Cadarache (France). NRTA was applied to determine the nuclide composition of UO 2 , Al 2 O 3 and liquid samples that were doped with silver. The volume number densities of 238 U, 107 Ag and 109 Ag obtained by NRTA are within 2 % fully consistent with the values that are quoted by the manufacturer. In addition, the NRTA data reveal a tungsten contamination which is not reported by the provider. It is shown that such a contamination contributes by up to 5.7 % to the reactivity worth.

Neutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed.

Apolipoprotein E (ApoE), an important mediator of lipid transportation in plasma and the nervous system, plays a large role in diseases such as atherosclerosis and Alzheimer's. The major allele variants ApoE3 and ApoE4 differ only by one amino acid. However, this difference has major consequences for the physiological behaviour of each variant. In this paper, we follow (i) the initial interaction of lipid-free ApoE variants with model membranes as a function of lipid saturation, (ii) the formation of reconstituted High-Density Lipoprotein-like particles (rHDL) and their structural characterisation, and (iii) the rHDL ability to exchange lipids with model membranes made of saturated lipids in the presence and absence of cholesterol [1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) with and without 20 mol% cholesterol]. Our neutron reflection results demonstrate that the protein variants interact differently with the model ...

Spectroscopic ellipsometry (SE) and neutron reflection (NR) data for the adsorption of a monoclonal antibody (mAb, termed COE-3, pI 8.44) at the bare SiO2/water interface are compared here to the simulations based on Derjaguin-Landau-Verwey-Overbeek theory. COE-3 adsorption was characterized by an initial rapid increase in the surface-adsorbed amount (Γ) followed by a plateau. Only the initial rate of the increase in Γ was strongly correlated with the bulk concentration (0.002-0.2 mg/mL), with Γ at the plateau being about 2.2 mg/m2 (pH 5.5). Simulations captured COE-3 adsorption at equilibrium most accurately, the point at which the outgoing flux of molecules within the adsorbed plane matched the adsorption flux. Increasing the buffer pH from 5.5 to 9 increased Γ at equilibrium to ∼3 mg/m2 (0.02 mg/mL COE-3), revealing a dominant role for lateral repulsion between adsorbed mAb molecules. In contrast, increasing the buffer ionic strength (pH 6) reduced Γ, which was captured by simula...

The authors present a review of the systematic studies of the structure of macroscopically planar thin films at the air-liquid interface (water, alkali solution and silica hydrosol). A common feature of the considered works is the application of a model-independent approach to the analysis of X-ray reflectometry data, which does not require a priori assumptions about the structure of the object under study. It is shown that the experimental results obtained with the laboratory source in some cases are qualitatively on par with the results of those obtained with the use of synchrotron radiation source. The reproducibility of the effect of spontaneous ordering in films of amphiphilic organic molecules (phospholipids) at the surface of the colloidal solution of silica nanoparticles is demonstrated. The possibility of influencing the kinetics of the in situ formation of a phospholipid film by enriching the liquid substrate with alkali metal ions is also discussed.

BioRef will be a time-of-flight reflectometer complementing the monochromator based V6 reflectometer at Hahn-Meitner Institute. Combined with an in-situ infrared spectrometer it will be optimised for soft matter applications at solid-liquid interfaces. A flexible double-chopper setup together with a wavelength band chopper will enable the selection of well defined wavelength bands at different wavelength resolutions in order to optimize measurements with regard to the given application. The selection of different distances between the first choppers allow for choosing constant resolutions of δ λ/λ between 1% and 5% , while different frequencies of the choppers are intended to alter the used bandwidth. A width of the band of 4 Å up to 12 Å can be selected between a minimum wavelength of app. 3 Å and a maximum of 15 Å. Lower wavelength resolutions than 5% can be realised when giving up the constant resolution. A state-of-the-art 2D position sensitive 3 He detector will be used for the reflectivity measurements in horizontal scattering geometry. The time-of-flight mode is also chosen to realise the investigation of dynamic interface processes under shear and flow conditions. A q-range spanning 3 orders of magnitude and reflectivity measurements over 7 orders of magnitude are envisaged and their feasibility is supported by Monte Carlo simulations.

The applicability of standard methods for compositional analysis is limited for H-containing films. Neutron reflectometry is a powerful, non-destructive method that is especially suitable for these systems due to the large negative scattering length of H. In this work, we demonstrate how neutron reflectometry can be used to investigate thin films of yttrium hydride. Neutron reflectometry gives a strong contrast between the film and the surface oxide layer, enabling us to estimate the oxide thickness and oxygen penetration depths. A surface oxide layer of 5-10 nm thickness was found for unprotected yttrium hydride films. V

Biological membranes do not only occur as planar bilayer structures, but depending on the lipid composition, can also curve into intriguing three-dimensional structures. In order to fully understand the biological implications as well as to reveal the full potential for applications, e.g. for drug delivery and other biomedical devices, of such structures, well-defined model systems are required. Here, we discuss the formation of lipid non-lamellar liquid crystalline (LC) surface layers spin-coated from the constituting lipids followed by hydration of the lipid layer. We demonstrate that hybrid lipid polymer films can be formed with different properties compared with the neat lipid LC layers. The nanostructure and morphologies of the lipid films formed reflect those in the bulk. Most notably, mixed lipid layers, which are composed of glycerol monooleate and diglycerol monooleate with poly(N-isopropylacrylamide) nanogels, can form films of reverse cubic phases that are capable of resp...

We have succeeded in precisely measuring spin-precession angles of tunneling and nontunneling neutrons through double-rectangular, triple-rectangular, and multirectangular potential barriers represented by a ͓Permalloy45͑PA͒-germanium͑Ge͔͒ n-PA Fabry-Perot magnetic thin-film resonator for nϭ1, 2, and 10, respectively. The spin-precession angle due to the Fabry-Perot resonator shows the oscillation curve as a function of the incident angles, and the curve is well reproduced by the theoretical phase difference of ↑ and ↓ spin neutron wave functions based on the one-dimensional Schrödinger equation. We demonstrate that the amplitude of the curve is proportional to the number of germanium layers ͑wells͒ although the transmission probability remains constant.

We report on the design and first tests of a device allowing for measurement of ultracold neutrons polarisation by means of the simultaneous analysis of the two spin components. The device was developed in the framework of the neutron electric dipole moment experiment at the Paul Scherrer Institute. Individual parts and the entire newly built system have been characterised with ultracold neutrons. The gain in statistical sensitivity obtained with the simultaneous spin analyser is (18.2 ± 6.1)% relative to the former sequential analyser under nominal running conditions.

In case a mirror world with a copy of our ordinary particle spectrum would exist, the neutron n and its degenerate partner, the mirror neutron n 0 , could potentially mix and undergo nn 0 oscillations. The interaction of an ordinary magnetic field with the ordinary neutron would lift the degeneracy between the mirror partners, diminish the n 0 amplitude in the n wave function and, thus, suppress its observability. We report an experimental comparison of ultracold neutron storage in a trap with and without superimposed magnetic field. No influence of the magnetic field is found and, assuming negligible mirror magnetic fields, a limit on the oscillation time nn 0 > 103 s (95% C.L.) is derived.

Phase separation of the weakly incompatible blend system polystyrene and polyparamethylstyrene confined in isolated droplets is investigated. The droplet geometry imposes a two-dimensional spatial restriction. With specular, diffuse and grazing incidence small-angle neutron scattering the surface topography as well as the chemical morphology inside the droplets is determined. Due to the differences in surface tension, a core-shell-like structure characterized by one most prominent length scale inside the droplets is installed.

The IN4C spectrometer has been constructed by ILL in collaboration with the Italian Istituto Nazionale Fisica della Materia, INFM. The instrument was designed in order to have a high counting rate and signal-to-noise ratio with optimised resolution performance. The main ingredients for attaining these objectives are the focusing optics, the e$cient background suppression by the chopper system, and the large detector area. In our contribution we shall present the results on the "rst operational tests.

The component depth distribution was investigated for thin films of binary polystyrene (PS) blends with different molecular weights by using neutron reflectometry to understand the mechanism of dewetting suppression effect induced with a small amount of higher molecular weight homologue. In-situ neutron reflectivity measurement revealed the slight difference in temporal evolution of the component depth distribution induced by thermal annealing according to the molecular weight of the additive. The higher molecular weight component depleted from air surface of the film due to less penalty in conformational entropy at a flat surface, though deuterated component enthalpically favors air surface. On the other hand, neither depletion nor segregation of the larger molecule was clearly observed at the interface with the substrate. This could be attributed to physical adsorption of polystyrenes at the silicon substrate through interaction with silanol groups existing at the substrate surface.

Results of a high-resolution x-ray reflectivity study of growth morphology and ordering of thin liquidcrystal films on flat glass substrate are reported. An adsorbed bilayer of crystalline order, under three dimensional clusters, was found to persist well beyond the nematic to isotropic transition. This adsorbed layer appears to be related to the surface memory effects in liquid-crystal devices. The morphology of these films can be described by the Stranski-Krastanov growth mode.

We show that the quantum chirality of charge carriers in graphene can be mimicked in optical structures. More precisely, we demonstrate that the particular form of the transmission coefficient at an interface in graphene between regions with different parameters can be retrieved in optics in either isotropic, gyrotropic and electro-optic materials or in complex conjugate materials. Quantitative analogies are found, at least in some parameter range, between optical and quantum parameters for which the transmission coefficient is similar in the optical and quantum cases, and hence the optical fields and quantum wavefunctions propagate in a similar manner.