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Sample records for surface neutron probe

  1. Neutron probe measurement of soil water content close to soil surface

    International Nuclear Information System (INIS)

    Faleiros, M.C.; Ravelo S, A.; Souza, M.D. de

    1993-01-01

    The problem of neutron probe soil water content measurements close to soil surface is analysed from the spatial variability and also from the slow neutron loss to the atmosphere points of view. Results obtained on a dark red latosol of the county of Piracicaba, SP, indicate the possibility of precisely measuring the neutron sphere of influence when different media are used on soil surface. (author). 7 refs, 5 figs, 1 tab

  2. Neutrons as a probe

    International Nuclear Information System (INIS)

    Iizumi, Masashi

    1993-01-01

    As an introduction to the symposium a brief overview will be given about the features of neutrons as a probe. First it will be pointed out that the utilization of neutrons as a probe for investigating the structural and dynamical properties of condensed matters is a benign gift eventuated from the release of atomic energy initiated by Enrico Fermi exactly half century ago. Features of neutrons as a probe are discussed in accordance with the four basic physical properties of neutrons as an elementary particle; (1) no electric charge (the interaction with matter is nuclear), (2) the mass of neutron is 1 amu, (3) spin is 1/2 and (4) neutrons have magnetic dipole moment. Overview will be given on the uniqueness of neutrons as a probe and on the variety in the way they are used in the wide research area from the pure science to the industrial applications. (author)

  3. Development of Neutron Probes for Characterization of Hazardous Materials in the Sub-surface Medium

    International Nuclear Information System (INIS)

    Keegan, R.P.; McGrath, C.A.; Lopez, J.C.

    2002-01-01

    Neutron probes are being developed at the Idaho National Engineering and Environmental Laboratory (INEEL) for the detection, identification and quantification of hazardous materials in the ground. Such materials include plutonium, uranium, americium, chlorine and fluorine. Both a Neutron Gamma (NG) probe and a Prompt Fission Neutron (PFN) probe are being developed. The NG probe is used primarily for nuclide identification and quantification measurements. The PFN is used mostly for the detection and measurement of fissile material, but also for the determination of thermal neutron macroscopic absorption cross sections of the various elements comprising the ground matrix. Calibration of these probes will be carried out at the INEEL using an indoor facility that has been designed for this activity

  4. A comparison of different neutron probes calibration method for the soil surface and their radiation effect on the users

    Energy Technology Data Exchange (ETDEWEB)

    Arslan, A; Razzouk, A K; Al-Ain, F [Atomic Energy commission , Damascus (Syrian Arab Republic). Dept of Radiation Agriculture

    1996-08-01

    In situ calibration curves were installed for the soil surface using different models of depth neutron probes and different adaptors. depth beutron probe readings increased with increasing the number of teflon plastic blocks deposited on the soil surface. The intercept of the straight line regression analysis decreased with increasing of teflon plastics blocks deposited on the soil surface in all sites. The least exposure was with depth probe with surface reflectors. This study proves the possibility of measuring the moisture content of the soil surface by using a depth probe with a block laid on the surface, without a danger of receiving the thresgold of radiation dose. (author). 10 Refs., 2 Figs., 8 Tabs.

  5. Neutron-neutron probe for uranium exploration

    International Nuclear Information System (INIS)

    Smith, R.C.

    1979-01-01

    A neutron activation probe for assaying the amount of fissionable isotopes in an ore body is described which comprises a casing which is movable through a borehole in the ore body, a neutron source and a number of delayed neutron detectors arranged colinearly in the casing below the neutron source for detecting delayed neutrons

  6. Neutron reflectometry: A probe for materials surfaces. Proceedings of a technical meeting

    International Nuclear Information System (INIS)

    2006-01-01

    Research reactors play an important role in delivering the benefits of nuclear science and technology. The IAEA, through its project on the effective utilization of research reactors, has been providing technical support to Member States and promotes activities related to specific applications. Neutron beam research is one of the main components in materials science studies. Neutron reflectometry is extremely useful for characterizing thin films and layered structures, polymers, oxide coatings on metals and biological membranes. The neutron has been a major probe for investigating magnetic materials. Development of magnetic multilayers is important for diverse applications in sensors, memory devices, etc. The special nature of the interaction of the neutron with matter makes it an important tool to locate low z elements in the presence of high z elements, which is useful in biology and polymer science. The role of neutron reflectometry in research and development in materials science and technology was discussed in a consultants meeting held in 2003. Following this, a technical meeting was organized from 16 to 20 August 2004 in Vienna to discuss the current status of neutron reflectometry, including the instrumentation, data acquisition, data analysis and applications. Experts in the field of neutron reflectometry presented their contributions, after which there was a brainstorming session on various aspects of the technique and its applications. This publication is the outcome of deliberations during the meeting and the presentations by the participants. This publication will be of use to scientists planning to develop a neutron reflectometer at research reactors. It will also help disseminate knowledge and information to material scientists, biologists and chemists working towards characterizing and developing new materials

  7. Dynamics of Phenanthrenequinone on Carbon Nano-Onion Surfaces Probed by Quasielastic Neutron Scattering

    International Nuclear Information System (INIS)

    Mamontov, Eugene; Brown, Gilbert M.; Overbury, Steven H.; Mavila Chathoth, Suresh

    2012-01-01

    We used quasielastic neutron scattering (QENS) to study the dynamics of phenanthrenequinone (PQ) on the surface of onion-like carbon (OLC), or so called carbon onions, as a function of surface coverage and temperature. For both the high- and low-coverage samples, we observed two diffusion processes; a faster process and nearly an order of magnitude slower process. On the high-coverage surface, the slow diffusion process is of long-range translational character, whereas the fast diffusion process is spatially localized on the length scale of ∼ 4.7. On the low-coverage surface, both diffusion processes are spatially localized; on the same length scale of ∼ 4.7 for the fast diffusion and a somewhat larger length scale for the slow diffusion. Arrhenius temperature dependence is observed except for the long-range diffusion on the high-coverage surface. We attribute the fast diffusion process to the generic localized in-cage dynamics of PQ molecules, and the slow diffusion process to the long-range translational dynamics of PQ molecules, which, depending on the coverage, may be either spatially restricted, or long-range. On the low-coverage surface, uniform surface coverage is not attained, and the PQ molecules experience the effect of spatial constraints on their long-range translational dynamics. Unexpectedly, the dynamics of PQ molecules on OLC as a function of temperature and surface coverage bears qualitative resemblance to the dynamics of water molecules on oxide surfaces, including practically temperature-independent residence times for the low-coverage surface. The dynamics features that we observed may be universal across different classes of surface adsorbates.

  8. Radiation safety of soil moisture neutron probes

    International Nuclear Information System (INIS)

    Oresegun, M.O.

    2000-01-01

    The neutron probe measures sub-surface moisture in soil and other materials by means of high energy neutrons and a slow (thermal) neutron detector. Exposure to radiation, including neutrons, especially at high doses, can cause detrimental health effects. In order to achieve operational radiation safety, there must be compliance with protection and safety standards. The design and manufacture of commercially available neutron moisture gauges are such that risks to the health of the user have been greatly reduced. The major concern is radiation escape from the soil during measurement, especially under dry conditions and when the radius of influence is large. With appropriate work practices as well as good design and manufacture of gauges, recorded occupational doses have been well below recommended annual limits. It can be concluded that the use of neutron gauges poses not only acceptable health and safety risks but, in fact, the risks are negligible. Neutron gauges should not be classified as posing high potential health hazards. (author)

  9. Neutrons for probing matter

    International Nuclear Information System (INIS)

    Torres, F. Ed.; Mazzucchetti, D.

    2008-01-01

    The authors tell the story of the French Orphee reactor located in Saclay from the decision to build it in the seventies, to its commissioning in 1980, to its upgrading in the nineties and to its today's operating life. As early as its feasibility studies Orphee has been designed as a dual-purpose reactor: scientific research for instance in crystallography and magnetism, and industrial uses like neutron radiography, silicon doping or radionuclide production. This book is divided into 4 parts: 1) the neutron: an explorer of the matter, 2) the Orphee reactor: a neutron source, 3) the adventurers of the matter: Leon Brillouin laboratory's staff, and 4) the perspectives for neutrons

  10. Quality of the neutron probe calibration curve

    International Nuclear Information System (INIS)

    Libardi, Paulo Leonel; Moraes, Sergio Oliveira

    1997-01-01

    An experiment of neutron probe calibration has been performed, involving various volume size samples and collected at various distances from the access tubes. The experiment aimed to give some answers to questions such as suitable sample physical volume, always use of the same volume and sample distance from the neutron probe access tube

  11. Probing fine magnetic particles with neutron scattering

    International Nuclear Information System (INIS)

    Pynn, R.

    1991-01-01

    Because thermal neutrons are scattered both by nuclei and by unpaired electrons, they provide an ideal probe for studying the atomic and magnetic structures of fine-grained magnetic materials, including nanocrystalline solids, thin epitaxial layers, and colloidal suspensions of magnetic particles, known as ferrofluids. Diffraction, surface reflection, and small angle neutron scattering (SANS) are the techniques used. With the exception of surface reflection, these methods are described in this article. The combination of SANS with refractive-index matching and neutron polarisation analysis is particularly powerful because it allows the magnetic and atomic structures to be determined independently. This technique has been used to study both dilute and concentrated ferrofluid suspensions of relatively monodisperse cobalt particles, subjected to a series of applied magnetic fields. The size of the cobalt particle core and the surrounding surfactant layer were determined. The measured interparticle structure factor agrees well with a recent theory that allows correlations in binary mixtures of magnetic particles to be calculated in the case of complete magnetic alignment. When one of the species in such a binary mixture is a nonmagnetic, cyclindrical macromolecule, application of a magnetic field leads to some degree of alignment of the nonmagnetic species. This result has been demonstrated with tobacco mosaic virus suspended in a water-based ferrofluid

  12. Neutron-based portable drug probe

    International Nuclear Information System (INIS)

    Womble, P. C.; Vourvopoulos, G.; Ball Howard, J.; Paschal, J.

    1999-01-01

    Based on previous measurements, a probe prototype for contraband detection utilizing the neutron technique of Pulsed Fast-Thermal Neutron Analysis (PFTNA) is being constructed. The prototype weighs less than 45 kg and is composed of a probe (5 cm diameter), a power pack and a data acquisition and display system. The probe is designed to be inserted in confined spaces such as the boiler of a ship or a tanker truck filled with liquid. The probe provides information on a) the elemental content, and b) the density variations of the interrogated object. By measuring elemental content, the probe can differentiate between innocuous materials and drugs. Density variations can be found through fast neutron transmission. In all cases, hidden drugs are identified through the measurement of the elemental content of the object, and the comparison of expected and measured elemental ratios

  13. Expectations for neutrons as microscopic probes

    International Nuclear Information System (INIS)

    Date, M.

    1993-01-01

    Neutrons have been used as microscopic probes to study structural and dynamical properties of various materials. In this paper I shall give a comparative study of the neutron research in the condensed matter physics with other typical microscopic methods such as X-rays, laser optics, magnetic resonances, Moessbauer effect and μSR. It is emphasized that the neutron study will extensively be important in future beyond the condensed matter physics. Chemistry, biology, earth sciences, material engineerings and medical sciences will become new frontiers for neutron study. (author)

  14. Calibration technique for the neutron surface moisture measurement system

    International Nuclear Information System (INIS)

    Watson, W.T.; Shreve, D.C.

    1996-01-01

    A technique for calibrating the response of a surface neutron moisture measurement probe to material moisture concentration has been devised. Tests to ensure that the probe will function in the expected in-tank operating environment are also outlined

  15. Neutronic density perturbation by probes

    International Nuclear Information System (INIS)

    Vigon, M. A.; Diez, L.

    1956-01-01

    The introduction of absorbent materials of neutrons in diffuser media, produces local disturbances of neutronic density. The disturbance depends especially on the nature and size of the absorbent. Approximated equations which relates te disturbance and the distance to the absorbent in the case of thin disks have been drawn. The experimental comprobation has been carried out in two especial cases. In both cases the experimental results are in agreement with the calculated values from these equations. (Author)

  16. Project and construction of counting system for neutron probe

    International Nuclear Information System (INIS)

    Monteiro, W.P.

    1985-01-01

    A counting system was developed for coupling neutron probe aiming to register pulses produced by slow neutron interaction in the detector. The neutron probe consists of fast neutron source, thermal neutron detector, amplifier circuit and pulse counting circuit. The counting system is composed by counting circuit, timer and signal circuit. (M.C.K.)

  17. Irrigation scheduling with the neutron probe

    International Nuclear Information System (INIS)

    Travers, P.

    1987-01-01

    The operational theory of the neutron probe is briefly outlined and its application and uses discussed in relation to determination of soil compaction and irrigation scheduling. Graphic examples are given of alluvial soil moisture profiles and how this information can be used to improve trickle irrigation in vineyards. 3 refs., 7 figs

  18. When beauty is only skin deep; optimizing the sensitivity of specular neutron reflectivity for probing structure beneath the surface of thin filmsa)

    Science.gov (United States)

    Majkrzak, Charles F.; Carpenter, Elisabeth; Heinrich, Frank; Berk, Norman F.

    2011-11-01

    Specular neutron reflectometry has become an established probe of the nanometer scale structure of materials in thin film and multilayered form. It has contributed especially to our understanding of soft condensed matter of interest in polymer science, organic chemistry, and biology and of magnetic hard condensed matter systems. In this paper we examine a number of key factors which have emerged that can limit the sensitivity of neutron reflection as such a probe. Among these is loss of phase information, and we discuss how knowledge about material surrounding a film of interest can be applied to help resolve the problem. In this context we also consider what role the quantum phenomenon of interaction-free measurement might play in enhancing the statistical efficiency for obtaining reflectivity or transmission data.

  19. Radioactive Probes on Ferromagnetic Surfaces

    CERN Multimedia

    2002-01-01

    On the (broad) basis of our studies of nonmagnetic radioactive probe atoms on magnetic surfaces and at interfaces, we propose to investigate the magnetic interaction of magnetic probe atoms with their immediate environment, in particular of rare earth (RE) elements positioned on and in ferromagnetic surfaces. The preparation and analysis of the structural properties of such samples will be performed in the UHV chamber HYDRA at the HMI/Berlin. For the investigations of the magnetic properties of RE atoms on surfaces Perturbed Angular Correlation (PAC) measurements and Mössbauer Spectroscopy (MS) in the UHV chamber ASPIC (Apparatus for Surface Physics and Interfaces at CERN) are proposed.

  20. Atomic beams probe surface vibrations

    International Nuclear Information System (INIS)

    Robinson, A.L.

    1982-01-01

    In the last two years, surface scientist have begun trying to obtain the vibrational frequencies of surface atoms in both insulating and metallic crystals from beams of helium atoms. It is the inelastic scattering that researchers use to probe surface vibrations. Inelastic atomic beam scattering has only been used to obtain vibrational frequency spectra from clean surfaces. Several experiments using helium beams are cited. (SC)

  1. Zeeman splitting of surface-scattered neutrons

    International Nuclear Information System (INIS)

    Felcher, G.P.; Adenwalla, S.; De Haan, V.O.; Van Well, A.A.

    1995-01-01

    If a beam of slow neutrons impinges on a solid at grazing incidence, the neutrons reflected can be used to probe the composition and magnetization of the solid near its surface. In this process, the incident and reflected neutrons generally have identical kinetic energies. Here we report the results of an experiment in which subtle inelastic scattering processes are revealed as relatively large deviations in scattering angle. The neutrons are scattered from a ferromagnetic surface in the presence of a strong ambient magnetic field, and exhibit a small but significant variation in kinetic energy as a function of the reflection angle. This effect is attributable to the Zeeman splitting of the energies of the neutron spin states due to the ambient magnetic field: some neutrons flip their spins upon reflection from the magnetized surface, thereby exchanging kinetic energy for magnetic potential energy. The subtle effects of Zeeman splitting are amplified by the extreme sensitivity of grazing-angle neutron scattering, and might also provide a useful spectroscopic tool if significant practical obstacles (such as low interaction cross-sections) can be overcome. (author)

  2. Probing thermonuclear burning on accreting neutron stars

    Science.gov (United States)

    Keek, L.

    2008-12-01

    Neutron stars are the most compact stars that can be directly observed, which makes them ideal laboratories to study physics at extreme densities. Neutron stars in low-mass X-ray binaries accrete hydrogen and helium from a lower-mass companion star through Roche lobe overflow. This matter undergoes thermonuclear burning in the neutron star envelope, creating carbon and heavier elements. The fusion process may proceed in an unstable manner, resulting in a thermonuclear runaway. Within one second the entire surface is burned, which is observable as a sharp rise in the emitted X-ray flux: a type I X-ray burst. Afterwards the neutron star surface cools down on a timescale of ten to one hundred seconds. During these bursts the surface of an accreting neutron star can be observed directly, which makes them instrumental for studying this type of stars. We have studied rare kinds of X-ray bursts. One such rare burst is the superburst, which lasts a thousand times longer than an ordinary burst. Superbursts are thought to result from the explosive burning of a thick carbon layer, which lies deeper inside the neutron star, close to a layer known as the crust. A prerequisite for the occurrence of a superburst is a high enough temperature, which is set by the temperature of the crust and the heat conductivity of the envelope. The latter is lowered by the presence of heavy elements that are produced during normal X-ray bursts. Using a large set of observations from the Wide Field Camera's onboard the BeppoSAX satellite, we find that, at high accretion rate, sources which do not exhibit normal bursts likely have a longer superburst recurrence time, than the observed superburst recurrence time of one burster. We analyze in detail the first superburst from a transient source, which went into outburst only 55 days before the superburst. Recent models of the neutron star crust predict that this is too small a time to heat the crust sufficiently for superburst ignition, indicating

  3. A new type of compensated neutron logging probe

    International Nuclear Information System (INIS)

    Ji Changsong; Shang Xiulan; Dai Zhude; Huang Heyi; Zhang Jianguo; Zu Shihuan; Zhao Jianqiang

    1988-01-01

    A new type of compensated neutron logging probe with glass scintillators has been designed. High sensitivity, long plateau and stability are the features of this probe which differs from the probes with 3 He or LiI(Eu) detector. From the results of field application the measured porosity is in good correspondence with the one obtained by rock core sampling method

  4. Magnetism and magnetic materials probed with neutron scattering

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  5. Magnetism and magnetic materials probed with neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-15

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

  6. Influence of access hole parameters on neutron moisture probe readings

    International Nuclear Information System (INIS)

    Abeele, W.V.

    1979-10-01

    Computing soil moisture content with a neutron probe requires use of a calibration curve that considers the thermal neutron capture cross section of the hole liner, as well as the hole diameter. The influence of steel, polyvinyl chloride, and aluminum casings that fit 0.051- to 0.102-m hole diameters was determined by comparison with neutron probe readings in uncased holes of corresponding diameters. Eccentricity of probe location was considered a potentially significant variable. The experiment was run in disturbed Bandelier tuff with an average dry density of 1.35g . cm -3 and moisture content of 3.8 to 26.7% by volume. The casing material and hole diameter influenced the probe readings significantly, whereas eccentric location of the probe did not. Regression analyses showed an almost perfect inverse linear correlation between hole diameter and count rate

  7. Influence of access hole parameters on neutron moisture probe readings

    International Nuclear Information System (INIS)

    Abeele, W.V.

    1978-04-01

    Computing soil moisture content with a neutron probe requires use of a calibration curve that considers the thermal neutron capture cross section of the hole liner as well as the hole diameter. The influence of steel, polyvinyl chloride, and aluminum casings that fit 0.051 to 0.102-hole diameters was determined by comparison with neutron probe readings in uncased holes of corresponding diameters. Eccentricity of probe location was considered a potentially significant variable. The relationship between hole diameter and count rate also was investigated. The experiment was run in disturbed Bandelier tuff with an average dry density of 1.2 g . cm -3 and moisture content of 1.3 to 35.5% by volume. The casing material and hole diameter influenced the probe readings significantly, whereas eccentric location of the probe did not. Regression analyses showed an almost perfect inverse linear correlation between hole diameter and count rate

  8. Methods for Probing Magnetic Films with Neutrons

    Science.gov (United States)

    Kozhevnikov, S. V.; Ott, F.; Radu, F.

    2018-03-01

    We review various methods in the investigation of magnetic films with neutrons, including those based on the effects of Larmor precession, Zeeman spatial splitting of the beam, neutron spin resonance, and polarized neutron channeling. The underlying principles, examples of the investigated systems, specific features, applications, and perspectives of these methods are discussed.

  9. Soil texture and depth influence on the neutron probe calibration

    International Nuclear Information System (INIS)

    Santos, Reginaldo Ferreira; Carlesso, Reimar

    1998-01-01

    The neutron probe is an equipment used on determination of the soil water content, based on the fast neutron attenuation. Therefore, there is a calibration need in the field and, consequently, to verify the soil texture and depth influence for to determining the calibration curves in relation to the water content. The study was developed at Santa Maria's Federal University in a lisimeter group, protected from the rains with transparent plastic. There different soil textures, three depths (10, 30 and 50 cm from the soil surface) and four replicates were used. Linear regression equations between neutron counts and soil water contents were made. The results showed that there was interference of the texture and depth of the soil, analyzed jointly, on the calibration curves, and the observed and estimated values varied form o,02 to 0,06 cm3/cm3 of the soil water content and the correlation coefficients were 0,86 0,95 and 0,89 for clayray, franc-silt-clayey and franc-sandy, respectively. For soil texture and depth, analyzed separately, the differences among the values observed in the field and the estimated ones, varied from 0,0 to 0,02 cm3/cm3 soil water content and presented correlation coefficients between 0,97 and 1,0. (author)

  10. The performance and radiation exposure of some neutron probes in measuring the water content of the topsoil layer

    International Nuclear Information System (INIS)

    Arslan, A.; Razzouk, A.K.; Al-Ain, F.

    1997-01-01

    The use of neutron scattering technique for determining the soil surface water content is not popular due to the radiation escaping from the soil surface and the large errors in measurement. To compare the radiation exposure and the performance of different techniques statistically, 3 sites were selected. Five different neutron probe models and different adaptors were used with the depth probes. Exposure to neutrons and γ radiations, at various distances from the probes, were determined. In situ calibration curves were determined using different models of depth probes with a Solo surface reflector block, CPN surface adaptor, and different numbers of plastic Teflon parallelepiped, as well as surface Troxler 3401-B probes. Depth neutron probe readings increased with increasing number of Teflon plastic blocks deposited on the soil surface. The intercept of the straight line regression analysis of CR (count ratio, surface count over standard count) v. percentage water content on a volume basis decreased with increasing number of blocks deposited on the soil surface at all sites. The determination coefficient values of any depth probe with a Solo surface reflector or a block of 4-8 cm thickness were higher than those of a Troxler 3401-B surface probe or CPN 503 depth probe with its surface adaptor. The least exposure to radiation was with a depth probe with surface reflectors. This study proves the possibility of measuring the moisture content of the soil surface by using a depth neutron probe with a block laid on the surface, without danger of receiving the threshold dose of radiation. (authors)

  11. Dendrimer sensors probed with neutron reflectometry

    International Nuclear Information System (INIS)

    Cavaye, Hamish; Smith, Arthur R.G.; Burn, Paul L.; Lo, Shih-Chun; Meredith, Paul; Gentle, Ian R.; James, Michael; Nelson, Andrew

    2009-01-01

    Full text: Oxidative photoluminescence (PL) quenching utilizing conjugated polymers as the sensing has proved to be one of the best of many methods for sensing explosive analytes.[1] However are a number of issues that can make polymers difficult to work with, including complex morphologies reproducibility of syntheses, and the need to include elaborate structures to reduce the packing of the polymer chains. Dendrimers, consisting of a core, dendrons, and surface groups, address these issues by being monodisperse and modular in their design. Determining how analytes are sequestered into thin films is important for solid-state sensors. We show that thin (230 ± 30 A ) and thick (750 ± 50 A) films of a first-generation dendrimer comrised of 2-ethylhexyloxy surface groups, biphenyl-based dendrons, and a 9,9,9',9'-tetra-n-propyl-2,2'-bifluorene core, can rapidly and reversibly detect p-nitrotoll oxidative luminescence quenching. For both the thin and thick films the PL is quenched by just 4 s . Combined PL and neutron reflectometry measurements on pristine and analyte-satura showed that during the adsorption process the films swelled, being on average 4% thicker for thin and thick dendrimer films. At the same time the PL was completely quenched. On removal of the analyte the films returned to their original thickness and scattering length density, and the restored, showing that the sensing process was fully reversible.

  12. Aspheric surface measurement using capacitive probes

    Science.gov (United States)

    Tao, Xin; Yuan, Daocheng; Li, Shaobo

    2017-02-01

    With the application of aspheres in optical fields, high precision and high efficiency aspheric surface metrology becomes a hot research topic. We describe a novel method of non-contact measurement of aspheric surface with capacitive probe. Taking an eccentric spherical surface as the object of study, the averaging effect of capacitive probe measurement and the influence of tilting the capacitive probe on the measurement results are investigated. By comparing measurement results from simultaneous measurement of the capacitive probe and contact probe of roundness instrument, this paper indicates the feasibility of using capacitive probes to test aspheric surface and proposes the compensation method of measurement error caused by averaging effect and the tilting of the capacitive probe.

  13. Alternative technique to neutron probe calibration in situ

    International Nuclear Information System (INIS)

    Encarnacao, F.; Carneiro, C.; Dall'Olio, A.

    1990-01-01

    An alternative technique of neutron probe calibration in situ was applied for Podzolic soil. Under field condition, the neutron probe calibration was performed using a special arrangement that prevented the lateral movement of water around the access tube of the neutron probe. During the experiments, successive amounts of water were uniformly infiltrated through the soil profile. Two plots were set to study the effect of the plot dimension on the slope of the calibration curve. The results obtained shown that the amounts of water transferred to the soil profile were significantly correlated to the integrals of count ratio along the soil profile on both plots. In consequence, the slope of calibration curve in field condition was determined. (author)

  14. Neutrons: The kinder, gentler probe of condensed matter

    International Nuclear Information System (INIS)

    Axe, J.D.

    1989-01-01

    Neutrons play an increasingly important role in the characterization of advanced modern materials. They provide information that complements rather than competes with that provided by other scattering probes. Although neutrons require heroic efforts to produce, the techniques for using them are not particularly difficult, and with the advent of sufficient user friendly facilities, are becoming a routine tool in the arsenal of expanding numbers of materials scientists. 10 refs., 5 figs

  15. The neutron probe and the detection of soil moisture

    International Nuclear Information System (INIS)

    Luft, G.; Morgenschweis, G.

    1981-01-01

    The authors present a brief outline of the direct and indirect field methods used at present in soil moisture measurement; particularly the advantages and disadvantages of neutron diffusion measurement are illustrated by means of various types of instruments available. The recently developed Wellingford Neutron Moisture Probe IH II, used for hydrological and pedohydrological fieldwork respectively, is presented and the first test results concerning the handling, measuring time, measured volume and layer thickness are discussed. (orig.) [de

  16. Surface charge measurement using an electrostatic probe

    DEFF Research Database (Denmark)

    Crichton, George C; McAllister, Iain Wilson

    1998-01-01

    During the 1960s, the first measurements of charge on dielectric surfaces using simple electrostatic probes were reported. However it is only within the last 10 years that a proper understanding of the probe response has been developed. This situation arose as a consequence of the earlier studies...

  17. Probing the pairing interaction through two-neutron transfer reactions

    Directory of Open Access Journals (Sweden)

    Margueron J.

    2012-12-01

    Full Text Available The treatment of the pairing interaction in mean-field-based models is addressed. In particular, the possibility to use pair transfers as A tool to better constrain this interaction is discussed. First, pairing inter-actions with various density dependencies (surface/volume mixing are used in the microscopic Hartree-Fock-Bogoliubov + quasiparticle random-phase approximation model to generate the form factors to be used in reaction calculations. Cross sections for (p,t two-neutron transfer reactions are calculated in the one-step zero-range distorted-wave Born approximation for some Tin isotopes and for incident proton energies from 15 to 35 MeV. Three different surface/volume mixings of A zero-range density-dependent pairing interaction are employed in the microscopic calculations and the sensitivity of the cross sections to the different mixings is analyzed. Differences among the three different theoretical predictions are found espacially for the nucleus 136Sn and they are more important at the incident proton energy of 15 MeV. We thus indicate (p,t two-neutron transfer reactions with very neutron-rich Sn isotopes and at proton energies around 15 MeV as good experimental cases where the surface/volume mixing of the pairing interaction may be probed. In the second part of the manuscript, ground-state to ground-state transitions are investigated. Approximations made to estimate two-nucleon transfer probabilities in ground-state to ground-state transitions and the physical interpretation of these probabilities are discussed. Probabilities are often calculated by approximating both ground states of the initial nucleus A and of the final nucleus A±2 by the same quasiparticle vacuum. We analyze two improvements of this approach. First, the effect of using two different ground states with average numbers of particles A and A±2 is quantified. Second, by using projection techniques, the role of particle number restoration is analyzed. Our analysis

  18. Probing surface magnetism with ion beams

    International Nuclear Information System (INIS)

    Winter, H.

    2007-01-01

    Ion beams can be used to probe magnetic properties of surfaces by a variety of different methods. Important features of these methods are related to trajectories of atomic projectiles scattered from the surface of a solid target and to the electronic interaction mechanisms in the surface region. Both items provide under specific conditions a high sensitivity for the detection of magnetic properties in the region at the topmost layer of surface atoms. This holds in particular for scattering under planar surface channeling conditions, where under grazing impact atoms or ions are reflected specularly from the surface without penetration into the subsurface region. Two different types of methods are employed based on the detection of the spin polarization of emitted or captured electrons and on spin blocking effects for capture into atomic terms. These techniques allow one to probe the long range and short range magnetic order in the surface region

  19. Influence of density and chemical composition of soils in the neutrons probes answer

    International Nuclear Information System (INIS)

    Crispino, Marcos Luiz; Antonino, Antonio Celso Dantas; Dall'Olio, Attilio; Oliveira Lira, Carlos Alberto Brayner de; Carneiro, Clemente J. Gusmao

    1996-08-01

    The determination of soil humidity with neutron probes is based in the measure of the thermal neutron flux intensity and its behavior with the soil depend: soil's chemical composition; soils physical parameters; neutrons' energetic spectrum and neutron-source detector geometry.The objective of this paper is to apply the multigroup function theory to calculate a neutron probe calibration curve utilizing representatives parameters and coefficients of soils horizons in a experimental station in Zona da Mata, Pernambuco, Brazil

  20. Evaluation of Flat Surface Temperature Probes

    Science.gov (United States)

    Beges, G.; Rudman, M.; Drnovsek, J.

    2011-01-01

    The objective of this paper is elaboration of elements related to metrological analysis in the field of surface temperature measurement. Surface temperature measurements are applicable in many fields. As examples, safety testing of electrical appliances and a pharmaceutical production line represent case studies for surface temperature measurements. In both cases correctness of the result of the surface temperature has an influence on final product safety and quality and thus conformity with specifications. This paper deals with the differences of flat surface temperature probes in measuring the surface temperature. For the purpose of safety testing of electrical appliances, surface temperature measurements are very important for safety of the user. General requirements are presented in European standards, which support requirements in European directives, e.g., European Low Voltage Directive 2006/95/EC and pharmaceutical requirements, which are introduced in official state legislation. This paper introduces a comparison of temperature measurements of an attached thermocouple on the measured surface and measurement with flat surface temperature probes. As a heat generator, a so called temperature artifact is used. It consists of an aluminum plate with an incorporated electrical heating element with very good temperature stability in the central part. The probes and thermocouple were applied with different forces to the surface in horizontal and vertical positions. The reference temperature was measured by a J-type fine-wire (0.2 mm) thermocouple. Two probes were homemade according to requirements in the European standard EN 60335-2-9/A12, one with a fine-wire (0.2 mm) thermocouple and one with 0.5mm of thermocouple wire diameter. Additional commercially available probes were compared. Differences between probes due to thermal conditions caused by application of the probe were found. Therefore, it can happen that measurements are performed with improper equipment or

  1. Surface sampling concentration and reaction probe

    Science.gov (United States)

    Van Berkel, Gary J; Elnaggar, Mariam S

    2013-07-16

    A method of analyzing a chemical composition of a specimen is described. The method can include providing a probe comprising an outer capillary tube and an inner capillary tube disposed co-axially within the outer capillary tube, where the inner and outer capillary tubes define a solvent capillary and a sampling capillary in fluid communication with one another at a distal end of the probe; contacting a target site on a surface of a specimen with a solvent in fluid communication with the probe; maintaining a plug volume proximate a solvent-specimen interface, wherein the plug volume is in fluid communication with the probe; draining plug sampling fluid from the plug volume through the sampling capillary; and analyzing a chemical composition of the plug sampling fluid with an analytical instrument. A system for performing the method is also described.

  2. Neutron and gamma probes: Their use in agronomy. Second edition

    International Nuclear Information System (INIS)

    2003-01-01

    Water is an essential requirement for life on the planet. It is often the single most limiting factor in crop and livestock production. Water is a scarce resource in many urban and rural environments worldwide. According to the FAO, the global demand for fresh water is doubling every 21 years. The quality of the finite water supplies is also under threat from industrial, agricultural and domestic sources of pollution. The majority of crops are grown under rain-fed conditions and adequate water supply is the main factor limiting crop production in semi-arid and sub-humid regions. On the other hand, currently 20% of the world's arable land is under irrigation providing 35 to 40% of all agricultural production. Irrigation mismanagement poses a serious threat to the environment through groundwater pollution and salinization. It is therefore, essential that water resources be used efficiently by regular monitoring of soil-water status in the unsaturated zone. The neutron depth probe, a nuclear-based technique, is utilized worldwide for this purpose. The neutron moisture gauge, since its introduction some 40 years ago, can now be considered a routine method in soil water studies. Many developments have since been introduced, in particular electronic components, which have significantly improved performance and expanded applications. Although the neutron scattering method is routinely utilised in many developed countries, its use is still limited in developing countries due to several factors. Neutron depth probes contain radioactive sources, which will present health and environmental hazards if a probe is improperly used, stored or disposed of. National and international legislation and regulations must be complied with. The strategic objective of the sub-program Soil and Water Management and Crop Nutrition of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture is to develop and promote the adoption of nuclear-based technologies for optimising soil

  3. Synopsis of moisture monitoring by neutron probe in the unsaturated zone at Area G

    International Nuclear Information System (INIS)

    Vold, E.

    1997-01-01

    Moisture profiles from neutron probe data provide valuable information in site characterization and to supplement ground water monitoring efforts. The neutron probe precision error (reproducibility) is found to be about 0.2 vol% under in situ field conditions where the slope in moisture content with depth is varying slowly. This error is about 2 times larger near moisture spikes (e.g., at the vapor phase notch), due to the sensitivity of the probe response to vertical position errors on the order of 0.5 inches. Calibrations were performed to correct the downhole probe response to the volumetric moisture content determined on core samples. Calibration is sensitive to borehole diameter and casing type, requiring 3 separate calibration relations for the boreholes surveyed here. Power law fits were used for calibration in this study to assure moisture content results greater than zero. Findings in the boreholes reported here confirm the broad features seen previously in moisture profiles at Area G, a near-surface region with large moisture variability, a very dry region at greater depths, and a moisture spike at the vapor phase notch (VPN). This feature is located near the interface between the vitrified and vitrified stratigraphic units and near the base of the mesa. This report describes the in-field calibration methods used for the neutron moisture probe measurements and summarizes preliminary results of the monitoring program in the in-situ monitoring network at Area G. Reported results include three main areas: calibration studies, profiles from each of the vertical boreholes at Area G, and time-dependent variations in a select subset of boreholes. Results are reported here for the vertical borehole network. Results from the horizontal borehole network will be described when available

  4. Comparison of methods of calibration of a neutron probe by gravimetry or neutron-capture model

    International Nuclear Information System (INIS)

    Vachaud, G.; Royer, J.M.; Cooper, J.D.

    1977-01-01

    This paper presents a systematic analysis of two methods used for determining calibration curves of neutron probes. The uncertainties resulting from the use of the gravimetric method, with a linear correlation between count rates and water content of soil samples, are considered first. Particular care is given to the determination of errors in the values of water content and count rates, and to the difficulties arising from the choice of the correlation technique. The neutron-calibration curve of the soil was also obtained with a technique based on the determination of neutron thermal adsorption and diffusion constants. The importance of errors associated with this method is also analyzed. Different field examples are then presented. It appears that the neutron-capture technique should be particularly well suited for determining the calibration curve of clay soils or heterogeneous materials for which the gravimetric calibration technique cannot be applied with confidence. On the other hand, it is also shown that for a soil with a very well-defined gravimetric calibration curve, the neutron-capture technique gives results still at least as good as with the former method

  5. The use of neutron probes to determine evapotranspiration

    International Nuclear Information System (INIS)

    Can, O.; Kurttas, Y. S. K.

    2009-01-01

    Water is an essential requirement for life on the planet. It is often the single most limiting factor in crop and livestock production. Water is a scarce resource in many urban and rural environments worldwide. According to the FAO, the global demand for fresh water is doubling every 21 years. The quality of the finite water supplies is also under threat from industrial, agricultural and domestic sources of pollution. The majority of crops are grown under rain-fed conditions and adequate water supply is the main factor limiting crop production in semi-arid and sub-humid regions. On the other hand, currently 20% of the world's arable land is under irrigation providing 35 to 40% of all agricultural production. Irrigation mismanagement poses a serious threat to the environment through groundwater pollution and salinization. It is therefore, essential that water resources be used efficiently by regular monitoring of soil-water status in the unsaturated zone. The neutron depth probe, a nuclear-based technique, is utilized worldwide for this purpose. For a given region, the water balance is given by I+P-(D+ET)-R=±ΔS where P is the rainfall integrated over Δt (mm), I is the irrigation integrated over Δt (mm), ET is the evapotranspiration integrated over Δt (mm), R is the runoff integrated over Δt (mm), D is the water draining from the soil at depth L integrated over Δt (mm), and ΔS is the change in soil-water storage in layer during the interval Δt (mm) The most commonly used values of Δt are a few days, a week, a month, and a year. The increase or decrease of soil moisture in a given soil depth, can easily monitor with neutron probes. When the neutron probe calibration is done, the amount of moisture in the soil at the desired frequency and depth can be learned quickly. In 2006 a study for the evapotranspiration of satsuma mandarin tree has been identified. In a irrigation period (01-31.08.2006) for four soil layer, ET : 78,04 mm. in 0-30 cm depth, ET: 50,01 mm

  6. Certification of contact probe measurement of surface wave of Li jet for IFMIF

    Energy Technology Data Exchange (ETDEWEB)

    Okita, Takafumi, E-mail: okita@stu.nucl.eng.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka (Japan); Hoashi, Eiji; Yoshihashi, Sachiko [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka (Japan); Kondo, Hiroo; Kanemura, Takuji [Japan Atomic Energy Agency, 4002 Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki (Japan); Yamaoka, Nobuo; Horiike, Hiroshi [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka (Japan)

    2015-10-15

    Highlights: • We have conducted experiments of liquid lithium free-surface flow for IFMIF. • In the experiment using electro-contact probe apparatus, a droplet of liquid Li on the middle of measurement probe was observed. • Behavior of a droplet and false detections were observed by using HSV camera. • The error of the statistical result was roughly evaluated about 1%. • From results of numerical simulations, we obtained the detailed information about the behavior of a Li droplet. - Abstract: The international fusion material irradiation facility (IFMIF) is a neutron source for developing fusion reactor materials. A liquid lithium (Li) jet with free surface is planned as a target to generate intense neutron field. It is important to obtain information on the surface wave characteristic for safety of the facility and efficient neutron generation. Surface wave characteristics experiment using the liquid Li circulation facility is carried out at Osaka University. In our studies, measurement using an electro-contact probe apparatus is conducted and many data about surface wave height were taken. In this experiment, a liquid Li droplet was observed on the probe. To see effect due to droplets on the probe needle, images near the surface of the Li jet including the Li droplet were taken by HSV camera synchronized with probe contact signals, and correlation between the behavior of the Li droplet and signals was evaluated. From the results, when the droplet on the probe contacts of the droplet with the surface, signals obviously different from the regular signal were observed. The influence on the result of frequency was estimated and is approximately <1%. Accuracy of measurement using probe could be increased by carefully deleting false signals.

  7. Neutron and gamma probes: Their use in agronomy

    International Nuclear Information System (INIS)

    Bacchi, O.O.; Reichart, K.; Calvache, M.

    2002-01-01

    The concept of this training manual originated during a regional training workshop on the use of neutron probe in water and nutrient balance studies, organized in 1997 in the frame of an IAEA Regional Technical Co-operation Project for Latin America entitle Plant Nutrition, Water and Soil Management, for which the integrated approach was adopted. The original version (in Spanish) was a comprehensive manual covering theoretical and practical aspects required for the proper utilization of the equipment. The contributions of the peer reviewers, editors and technical translators of the three versions in English, French and Spanish have greatly enhanced the content and quality of the manual. It is hoped that this manual will be useful for future training events and serve as a key reference to soil/water scientists in the field of sustainable management of scarce water resources in both rain-fed and irrigated agricultural production systems

  8. Tree tomato water requirements determined by neutron probe

    International Nuclear Information System (INIS)

    1994-01-01

    The dynamics of water was studied at ''La Tola'', experimental teaching center of the Central University of Ecuador, in a sandy-loan, typic durustoll soil in which trees tomato were growing. All the components of the crop water balance were determined. Real evapotranspiration (ETR) was estimated through the mass balance method, using every 5-10 days a neutron probe to access the volumetric humidity of the soil. The real evapotranspiration was in direct relation with the growth of the crop, reaching its maximum value of 3,8 mm day-1, at vegetative stage. The soil layer supplying most of the water for the consumptive use of the crop was between 0-40 cm being the root activity also greater in that layer

  9. A multilayer surface detector for ultracold neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhehui, E-mail: zwang@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hoffbauer, M.A.; Morris, C.L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Callahan, N.B.; Adamek, E.R. [Indiana University, Bloomington, IN 47405 (United States); Bacon, J.D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Blatnik, M. [Cleveland State University, Cleveland, OH 44115 (United States); Brandt, A.E. [North Carolina State University, Raleigh, NC 27695 (United States); Broussard, L.J.; Clayton, S.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Cude-Woods, C. [North Carolina State University, Raleigh, NC 27695 (United States); Currie, S. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Dees, E.B. [North Carolina State University, Raleigh, NC 27695 (United States); Ding, X. [Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States); Gao, J. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Gray, F.E. [Regis University, Denver, CO 80221 (United States); Hickerson, K.P. [University of California Los Angeles, Los Angeles, CA 90095 (United States); Holley, A.T. [Tennessee Technological University, Cookeville, TN 38505 (United States); Ito, T.M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Liu, C.-Y. [Indiana University, Bloomington, IN 47405 (United States); and others

    2015-10-21

    A multilayer surface detector for ultracold neutrons (UCNs) is described. The top {sup 10}B layer is exposed to vacuum and directly captures UCNs. The ZnS:Ag layer beneath the {sup 10}B layer is a few microns thick, which is sufficient to detect the charged particles from the {sup 10}B(n,α){sup 7}Li neutron-capture reaction, while thin enough that ample light due to α and {sup 7}Li escapes for detection by photomultiplier tubes. A 100-nm thick {sup 10}B layer gives high UCN detection efficiency, as determined by the mean UCN kinetic energy, detector materials, and other parameters. Low background, including negligible sensitivity to ambient neutrons, has also been verified through pulse-shape analysis and comparison with other existing {sup 3}He and {sup 10}B detectors. This type of detector has been configured in different ways for UCN flux monitoring, development of UCN guides and neutron lifetime research.

  10. Calibration of a neutron probe for determining the humidity in deep alluvial soils

    International Nuclear Information System (INIS)

    Ferrer, A.; Rivero, H.; Lopez, F.; Cantillo, O.

    1993-01-01

    Preliminary data for the calibration of a neutron probe in deep alluvial soils for determining the humidity are reported. Comparisons of Neutron flow behaviour with the depth of the land are established. A characteristic curve of amount of detected neutrons according to the humidity percentage (from 50 to 100 % of the field humidity) is obtained

  11. Neutrons on a surface of liquid helium

    Science.gov (United States)

    Grigoriev, P. D.; Zimmer, O.; Grigoriev, A. D.; Ziman, T.

    2016-08-01

    We investigate the possibility of ultracold neutron (UCN) storage in quantum states defined by the combined potentials of the Earth's gravity and the neutron optical repulsion by a horizontal surface of liquid helium. We analyze the stability of the lowest quantum state, which is most susceptible to perturbations due to surface excitations, against scattering by helium atoms in the vapor and by excitations of the liquid, comprised of ripplons, phonons, and surfons. This is an unusual scattering problem since the kinetic energy of the neutron parallel to the surface may be much greater than the binding energies perpendicular. The total scattering time of these UCNs at 0.7 K is found to exceed 1 h, and rapidly increases with decreasing temperature. Such low scattering rates should enable high-precision measurements of the sequence of discrete energy levels, thus providing improved tests of short-range gravity. The system might also be useful for neutron β -decay experiments. We also sketch new experimental propositions for level population and trapping of ultracold neutrons above a flat horizontal mirror.

  12. Probes for anionic cell surface detection

    Science.gov (United States)

    Smith, Bradley D.

    2013-03-05

    Embodiments of the present invention are generally directed to compositions comprising a class of molecular probes for detecting the presence of anionic cell surfaces. Embodiments include compositions that are enriched for these compositions and preparations, particularly preparations suitable for use as laboratory/clinical reagents and diagnostic indicators, either alone or as part of a kit. An embodiment of the invention provides for a highly selective agent useful in the discernment and identification of dead or dying cells, such as apoptotic cells, in a relatively calcium-free environment. An embodiment of the invention provides a selective agent for the identification of bacteria in a mixed population of bacterial cells and nonbacterial cells.

  13. Microarray of DNA probes on carboxylate functional beads surface

    Institute of Scientific and Technical Information of China (English)

    黄承志; 李原芳; 黄新华; 范美坤

    2000-01-01

    The microarray of DNA probes with 5’ -NH2 and 5’ -Tex/3’ -NH2 modified terminus on 10 um carboxylate functional beads surface in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) is characterized in the preseni paper. it was found that the microarray capacity of DNA probes on the beads surface depends on the pH of the aqueous solution, the concentra-tion of DNA probe and the total surface area of the beads. On optimal conditions, the minimum distance of 20 mer single-stranded DNA probe microarrayed on beads surface is about 14 nm, while that of 20 mer double-stranded DNA probes is about 27 nm. If the probe length increases from 20 mer to 35 mer, its microarray density decreases correspondingly. Mechanism study shows that the binding mode of DNA probes on the beads surface is nearly parallel to the beads surface.

  14. Microarray of DNA probes on carboxylate functional beads surface

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The microarray of DNA probes with 5′-NH2 and 5′-Tex/3′-NH2 modified terminus on 10 m m carboxylate functional beads surface in the presence of 1-ethyl-3-(3-dimethylaminopropyl)- carbodiimide (EDC) is characterized in the present paper. It was found that the microarray capacity of DNA probes on the beads surface depends on the pH of the aqueous solution, the concentration of DNA probe and the total surface area of the beads. On optimal conditions, the minimum distance of 20 mer single-stranded DNA probe microarrayed on beads surface is about 14 nm, while that of 20 mer double-stranded DNA probes is about 27 nm. If the probe length increases from 20 mer to 35 mer, its microarray density decreases correspondingly. Mechanism study shows that the binding mode of DNA probes on the beads surface is nearly parallel to the beads surface.

  15. Development of a neutron probe for soil humidity measurements using 6 LiI(Eu) detector

    International Nuclear Information System (INIS)

    Silva, Iran Jose Oliveira da; Khoury, Helen; Carneiro, Clemente J.G.

    2002-01-01

    A prototype of soil moisture probe was build using a crystal of 6 LiI(Eu) as a thermal neutron detector. Light pulses are produced by the exoergic nuclear reaction 6 Li (n,α) 3 He and transmitted through the light guide to a photomultiplier tube on the soil surface. Liquid light guides have several advantages when compared with bundle of glass fibers. First, liquid guides do not suffer from packing fraction losses spaces between fibers that cause reduced coupling efficiency. Second, repeated handling of liquid light guides does not result in the breakage typical of glass bundles, which reduces efficiency over time. Third, liquid guides have excellent UV transmission properties with a cut off the near infrared spectrum yielding an optimum transmission for visible applications. The major advantage of this prototype is the elimination of the electromagnetic interference inside of the soil. Tests were carried out aiming the improvement of electronic and technical viability aspects of neutrons probes. The soil moisture probe calibration curve was carried out in a drum of 60 cm diameter and 42 cm height. This drum was completely filled with an air dry soil. Counts in the center of the drum with the dry and saturated soils make possible to obtain the curves of the soil water content versus the normalized counts for two thermal neutron detectors. The medium value of the counts, the standard deviation and the number of counts were obtained for 6 LiI(Eu) and 3 He detectors, respectively for water, air dry, and saturated soil. From those measurements, a linear calibration curve was obtained for each of detectors. (author)

  16. Probe high-Tc Superconductors by neutron scattering

    International Nuclear Information System (INIS)

    Fauque, B.

    2007-10-01

    This research thesis explores two aspects of the phase diagram of high critical temperature superconductors: the evolution of AF correlations and the nature of the pseudo-gap phase. The author presents the problematic associated with these particular semiconductors, describes the neutron diffusion probe used in this study, and presents the three families of semiconductors investigated during this research: Bi 2 Sr 2 CaCu 2 O 8+x , YBa 2 Cu 3 O 6+x and La 2-x Sr x CuO 4 . He reports the results of the investigation of the spin dynamics in the Bi 2 Sr 2 CaCu 2 O 8+x . He reports a detailed investigation of the magnetic cross section associated with different types of non conventional magnetic orders proposed as candidates for the pseudo-gap phase. He reports and comments the results obtained for the pseudo-gap phase for the YBa 2 Cu 3 O 6+x and La 2-x Sr x CuO 4 families. Finally, the author discusses the consequences of the obtained results for the description of the diagram phase of high critical temperature semiconductors

  17. The orientation effect in the activities of neutronic probes

    International Nuclear Information System (INIS)

    Vigon, M. A.

    1956-01-01

    The formulae relating activity and position of a neutron irradiated Indium foil, have been verified experimentally. Measurements with both thin and thick foils for epithermal neutrons and with thick foils for thermal neutrons have been carried out. The experimental results agree qualitatively with the theoretical predictions. (Author)

  18. Comparative experimental and theoretical investigations of the DM neutron moisture probe

    DEFF Research Database (Denmark)

    Ølgaard, Povl Lebeck; Haahr, Vagner

    1967-01-01

    Theoretical and experimental investigations of the Danish produced DM subsurface moisture probe have been carried out at the Research Establishment Risö, and the results obtained are presented in this paper. The DM probe contains an Am-Be fast neutron source and has a glass scintillator containing...

  19. Surface energy of very neutron rich nuclei

    CERN Document Server

    Von Groote, H

    1976-01-01

    For a microscopic model calculation of the nuclear surface-energy coefficient sigma the surface energy is defined as the energy loss of an uncharged, semiinfinite (inhomogeneous) two-component system compared to an infinite (homogeneous) system with the same particle asymmetry delta . Using the Thomas-Fermi model the calculations are performed for a series of systems with increasing delta , starting from symmetric matter ( delta =0) and extending beyond the drip line of the neutrons, until the system undergoes a phase transition to a homogeneous system. The results for the surface energy as well as for the neutron skin and for the surface diffuseness are compared to the macroscopic approach of the Droplet Model (DM), which turns out to be a good approximation for small asymmetries typical for the region of the valley of beta -stability. For larger asymmetries, close to the drip lines, terms of higher order than contained in the DM approach are no longer negligible. Beyond the drip lines the pressure of the ou...

  20. Prospects for neutron probes in the 21st century

    International Nuclear Information System (INIS)

    Lander, G.H.

    1993-01-01

    In this paper I use the economic concepts of supply and demand to attempt to analyze the future prospects for neutron research. The most severe problem is one of supply of neutrons. The question is whether the demand will be sufficient to overcome the considerable political and financial problems associated with providing the supply. A different mode of operation may be necessary in neutron research, especially with reactor-based sources. (author)

  1. Binary pulsars as probes of neutron star birth

    NARCIS (Netherlands)

    Wijers, R.A.M.J.; van Paradijs, J.; van den Heuvel, E.P.J.

    1992-01-01

    We discuss two issues in the physics of neutron stars and their progenitors. The first is whether a neutron star receives a velocity kick when it is formed in the supernova-explosion of a massive star, and if it does, what is the characteristic magnitude, v(0), thereof? The second concerns the fate

  2. A pulsed source neutron reflectometer for surface studies

    International Nuclear Information System (INIS)

    Penfold, J.; Williams, W.G.

    1985-05-01

    A design for a neutron reflectometer for surface studies to be constructed at the SNS is presented. Examples of its use to study problems in surface chemistry, surface magnetism and low dimensional structures are highlighted. (author)

  3. Probing gas-surface interactions with a molecular beam

    International Nuclear Information System (INIS)

    Spruit, M.E.M.

    1988-01-01

    The dynamics of direct scattering, trapping and sticking in molecular beam scattering is probed. The O 2 /Ag interaction was chosen, using the close-packed (111) plane of Ag as target surface. 170 refs.; 22 figs.; 3 tabs

  4. Surface chemical reactions probed with scanning force microscopy

    NARCIS (Netherlands)

    Werts, M.P L; van der Vegte, E.W.; Hadziioannou, G

    1997-01-01

    In this letter we report the study of surface chemical reactions with scanning force microscopy (SFM) with chemical specificity. Using chemically modified SFM probes, we can determine the local surface reaction conversion during a chemical surface modification. The adhesion forces between a

  5. Probing properties of neutron stars with terrestrial nuclear reactions

    International Nuclear Information System (INIS)

    Li Baoan; Chen Liewen; Ko, C.M.; Steiner, Andrew W.; Yong Gaochan

    2006-01-01

    Heavy-ion reactions induced by neutron-rich nuclei provide the unique opportunity in terrestrial laboratories to constrain the nuclear symmetry energy Esym in a broad density range. A conservative constraint, 32(ρ/ρ0)0.7 < Esym(ρ) < 32(ρ/ρ0)1.1, around the nuclear matter saturation density ρ0 has recently been obtained from analyzing the isospin diffusion data within a transport model for intermediate energy heavy-ion reactions. This subsequently puts a stringent constraint on properties of neutron stars, especially their radii and cooling mechanisms

  6. Atomic probes of surface structure and dynamics

    International Nuclear Information System (INIS)

    Heller, E.J.; Jonsson, H.

    1992-01-01

    The following were studied: New semiclassical method for scattering calculations, He atom scattering from defective Pt surfaces, He atom scattering from Xe overlayers, thermal dissociation of H 2 on Cu(110), spin flip scattering of atoms from surfaces, and Car-Parrinello simulations of surface processes

  7. Neutron stars as probes of extreme energy density matter

    Indian Academy of Sciences (India)

    2015-05-07

    May 7, 2015 ... Neutron stars have long been regarded as extraterrestrial laboratories from which we can learn about extreme energy density matter at low temperatures. In this article, some of the recent advances made in astrophysical observations and related theory are highlighted. Although the focus is on the much ...

  8. Probing Trace-elements in Bitumen by Neutron Activation Analysis

    NARCIS (Netherlands)

    Nahar, S.N.; Schmets, A.J.M.; Scarpas, Athanasios

    Trace elements and their concentrations play an important role in both chemical and physical properties of bitumen. Instrumental Neutron Activation Analysis (INAA) has been applied to determine the concentration of trace elements in bitumen. This method requires irradiation of the material with

  9. Neutron stars as probes of extreme energy density matter

    Indian Academy of Sciences (India)

    2015-05-07

    May 7, 2015 ... and the orbital period decay due to the emission of gravitational radiation. ˙P = −. 192π ... masses severely restrict the EoS of neutron star matter. Masses ..... (9) Is unstable burning of carbon (C) the real cause of superbursts?

  10. Atomic probes of surface structure and dynamics

    International Nuclear Information System (INIS)

    Heller, E.J.; Jonsson, H.

    1992-01-01

    Progress for the period Sept. 15, 1992 to Sept. 14, 1993 is discussed. Semiclassical methods that will allow much faster and more accurate three-dimensional atom--surface scattering calculations, both elastic and inelastic, are being developed. The scattering of He atoms from buckyballs is being investigated as a test problem. Somewhat more detail is given on studies of He atom scattering from defective Pt surfaces. Molecular dynamics simulations of He + and Ar + ion sputtering of Pt surfaces are also being done. He atom scattering from Xe overlayers on metal surfaces and the thermalized dissociation of H 2 on Cu(110) are being studied. (R.W.R.) 64 refs

  11. LINEARLY POLARIZED PROBES OF SURFACE CHIRALITY

    NARCIS (Netherlands)

    VERBIEST, T; KAURANEN, M; MAKI, JJ; TEERENSTRA, MN; SCHOUTEN, AJ; NOLTE, RJM; PERSOONS, A

    1995-01-01

    We present a new nonlinear optical technique to study surface chirality. We demonstrate experimentally that the efficiency of second-harmonic generation from isotropic chiral surfaces is different for excitation with fundamental light that is +45 degrees and -45 degrees linearly polarized with

  12. Study on neutron beam probe. Study on the focused neutron beam

    Energy Technology Data Exchange (ETDEWEB)

    Kotajima, Kyuya; Suzuki, K.; Fujisawa, M.; Takahashi, T.; Sakamoto, I. [Tohoku Univ., Sendai (Japan). Faculty of Engineering; Wakabayashi, T.

    1998-03-01

    A monoenergetic focused neutron beam has been produced by utilizing the endoenergetic heavy ion reactions on hydrogen. To realize this, the projectile heavy ion energy should be taken slightly above the threshold energy, so that the excess energy converted to the neutron energy should be very small. In order to improve the capability of the focused neutron beam, some hydrogen stored metal targets have also been tested. Separating the secondary heavy ions (associated particles) from the primary ions (accelerated particles) by using a dipole magnet, a rf separator, and a particle identification system, we could directly count the produced neutrons. This will leads us to the possibility of realizing the standard neutron field which had been the empty dream of many neutron-related researchers in the world. (author)

  13. Neutrons probing the structure and dynamics of liquids

    International Nuclear Information System (INIS)

    Leclercq-Hugeux, F.; Coulet, M.V.; Gaspard, J.P.; Pouget, St.; Zanotti, J.M.

    2007-01-01

    This article illustrates the benefits of neutron techniques to the understanding of the liquid state. As opposed to the nearly complete order of crystals or the nearly complete disorder of gas, the disorder of a liquid is partial and results from dynamical events acting on a broad range of space and time scales. Consequently, no single, simple parameter can encompass the concept of order or disorder in the liquid state. The wide variety of neutron techniques (diffraction, quasi-elastic and inelastic scattering) is a key asset to solve the issue. Selected studies ranging over typical interactions and conditions relevant to liquids (metallic, covalent, molecular, liquids near a phase transition and confined fluids) are presented. In each case, both structural and dynamical aspects, along with the connections to complementary techniques (computer simulation, X-ray absorption and/or scattering) are highlighted. (authors)

  14. Delayed neutrons as a probe of nuclear charge distribution in fission of heavy nuclei by neutrons

    CERN Document Server

    Isaev, S G; Piksaikin, V M; Roshchenko, V A

    2001-01-01

    A method of the determination of cumulative yields of delayed neutron precursors is developed. This method is based on the iterative least-square procedure applied to delayed neutron decay curves measured after irradiation of sup 2 sup 3 sup 5 U sample by thermal neutrons. Obtained cumulative yields in turns were used for deriving the values of the most probable charge in low-energy fission of the above-mentioned nucleus.

  15. Delayed neutrons as a probe of nuclear charge distribution in fission of heavy nuclei by neutrons

    International Nuclear Information System (INIS)

    Isaev, S.G.; Piksaikin, V.M.; Kazakov, L.E.; Roshchenko, V.A.

    2002-01-01

    A method of the determination of cumulative yields of delayed neutron precursors is developed. This method is based on the iterative least-square procedure applied to delayed neutron decay curves measured after irradiation of 235 U sample by thermal neutrons. Obtained cumulative yields in turns were used for deriving the values of the most probable charge in low-energy fission of the above-mentioned nucleus. (author)

  16. A new technique for the calibration of neutron probes by volumetric method

    International Nuclear Information System (INIS)

    Encarnacao, F.A.F. da.

    1988-01-01

    Laboratory and field studies were performed for the determination of a calibration curve of a neutron probe in three different kinds of soils: Red Yellow PODZOLIC, LITOLIC and ALLUVIAL, in the last one laboratory studies were done to determine local humidity on the calibration curve parameters. (A.C.A.S.) [pt

  17. Correcting the error in neutron moisture probe measurements caused by a water density gradient

    International Nuclear Information System (INIS)

    Wilson, D.J.

    1988-01-01

    If a neutron probe lies in or near a water density gradient, the probe may register a water density different to that at the measuring point. The effect of a thin stratum of soil containing an excess or depletion of water at various distances from a probe in an otherwise homogeneous system has been calculated, producing an 'importance' curve. The effect of these strata can be integrated over the soil region in close proximity to the probe resulting in the net effect of the presence of a water density gradient. In practice, the probe is scanned through the point of interest and the count rate at that point is corrected for the influence of the water density on each side of it. An example shows that the technique can reduce an error of 10 per cent to about 2 per cent

  18. Probing Surface Electric Field Noise with a Single Ion

    Science.gov (United States)

    2013-07-30

    potentials is housed inside a Faraday cage providing more than 40 dB of attenuation for electromagnetic fields in the range of frequencies between 200...and measuring the ion quantum state [16]. Thus, by measuring the effect of electric field noise on the motional quantum state of the ion, one can probe...understand these effects . In summary, we have probed the electric field noise near an aluminum-copper surface at room temperature using a single trapped ion

  19. Surface Plasmon Polaritons Probed with Cold Atoms

    DEFF Research Database (Denmark)

    Kawalec, Tomasz; Sierant, Aleksandra; Panas, Roman

    2017-01-01

    We report on an optical mirror for cold rubidium atoms based on a repulsive dipole potential created by means of a modified recordable digital versatile disc. Using the mirror, we have determined the absolute value of the surface plasmon polariton (SPP) intensity, reaching 90 times the intensity...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-01-01

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

  1. Profiling water content in soils with TDR: Comparison with the neutron probe technique

    International Nuclear Information System (INIS)

    Laurent, J.P.

    2000-01-01

    In November 1996, at a site on the Grenoble campus a 1.2-m-long neutron access tube, a 0.8-m fibreglass Trime access tube and three sets of 1-m twin-rod TDR probes were installed. Weekly measurements were made over a 9-month period. In addition, soil samples were taken from time to time with an auger, to determine gravimetric water-contents. The soil bulk density profile was initially characterised by gammametry using a Campbell TM probe. A Troxler TM 4300 was used for the neutron-probe measurements. The TDR signals, for further processing by TDR-SSI, were logged using a Trase 2000 from Soil Moisture Equipment Corporation TM . TDR methods were employed without any special calibration of the permittivity/water-content relationship: standard internal calibrations of the devices or Topp polynomial relation were always applied. The results of all these water-content profiling methods were compared in three ways: (i) the water-content profiles were plotted directly on the same graph for different dates; (ii) all the water contents measured at all dates and all depths were plotted against a corresponding 'reference', namely neutron probe or gravimetry; (iii) water balances were calculated for each method and their respective time-profiles analysed. There was fairly good agreement among the three profiling methods, indicating that TDR is now a viable alternative to nuclear techniques for soil water-content profiling. (author)

  2. Surface analysis of Borkron glass for neutron optics applications

    International Nuclear Information System (INIS)

    Farnoux, B.; Maaza, M.; Maaza, M.; Samuel, F.; Sella, C.

    1991-01-01

    Grazing Angle Neutron Reflectometry, Optical and Mechanical Roughness Profilometry techniques have been used to study the effects of the polishing operations on the surface of Borkron Schott glass (special borosilicate glass for neutron optics applications) as the polishing tool pressure P and the mean grain size of the polishing powder Φ. The neutron reflectivity investigations have shown that there is formation of a layer at the surface glass substrate. This layer is less dense than the bulk substrate and its thickness is around 60A. The optical and mechanical profilometry measurements have shown that both roughness and waviness decrease with P and Φ. All the experimental results show a good correlation between the neutron refractive index, the thickness and the roughness of the surface layer and the waviness of the glass surface with the two mechanical polishing parameters. The previous techniques have been completed by Secondary Ion Mass Spectroscopy and Atomic Force Microscopy measurements

  3. Effect of some soil physical properties on water holding capacity, neutron probe calibration and salt movement

    International Nuclear Information System (INIS)

    Razzouk, A. K.

    2010-04-01

    This study was conducted in tow areas representing in silty soil in Southern Syria (Draa), loamy and sandy soil in Eastern Syria (Deir Al zour) to compare the soil effect on the calibration of the neutron probe, correlation coefficient, soil characteristics curve, soil solution content of nitrates, potassium and sodium for the estimation of the optimum sampling time of soil solution by porous ceramic cups. Regression analysis results showed that the three soils curves, in which the soil contained the lowest content of clay had a high correlation coefficient and decreased with increasing the clay content. Whereas, the correlation coefficient in sandy soil was 0.96 while decreased to 0.79 in silty soil. The hydraulic head increased with decreasing the water content, which was obvious in the three soils characteristic curves. The NO - 3 content decreased due to the plants roots absorption and leaching to deeper layers, while the NO - 3 content in the surfaces layer significantly decreased in the sandy soil. Results showed that equilibrium between the soil solution and the NO - 3 content in the solution in porous cups occurred within 8 days. (author)

  4. Validation of SMAP Root Zone Soil Moisture Estimates with Improved Cosmic-Ray Neutron Probe Observations

    Science.gov (United States)

    Babaeian, E.; Tuller, M.; Sadeghi, M.; Franz, T.; Jones, S. B.

    2017-12-01

    Soil Moisture Active Passive (SMAP) soil moisture products are commonly validated based on point-scale reference measurements, despite the exorbitant spatial scale disparity. The difference between the measurement depth of point-scale sensors and the penetration depth of SMAP further complicates evaluation efforts. Cosmic-ray neutron probes (CRNP) with an approximately 500-m radius footprint provide an appealing alternative for SMAP validation. This study is focused on the validation of SMAP level-4 root zone soil moisture products with 9-km spatial resolution based on CRNP observations at twenty U.S. reference sites with climatic conditions ranging from semiarid to humid. The CRNP measurements are often biased by additional hydrogen sources such as surface water, atmospheric vapor, or mineral lattice water, which sometimes yield unrealistic moisture values in excess of the soil water storage capacity. These effects were removed during CRNP data analysis. Comparison of SMAP data with corrected CRNP observations revealed a very high correlation for most of the investigated sites, which opens new avenues for validation of current and future satellite soil moisture products.

  5. Effect of some soil physical properties on water holding capacity, neutron probe calibration and salt movement

    International Nuclear Information System (INIS)

    Razzouk, A.

    2010-01-01

    This study was conducted in tow areas representing in silty soil in Southern Syria (Dra'a), loamy and sandy soil in Eastern Syria (Deir Al zour) to compare the soil effect on the calibration of the neutron probe, correlation coefficient, soil characteristics curve, soil solution content of nitrates, potassium and sodium for the estimation of the optimum sampling time of soil solution by porous ceramic cups. Regression analysis results showed that the three soils curves, in which the soil contained the lowest content of clay had a high correlation coefficient and decreased with increasing the clay content. Whereas, the correlation coefficient in sandy soil was 0.96 while decreased to 0.79 in silty soil. The hydraulic head increased with decreasing the water content, which was obvious in the three soils characteristic curves. The NO 3 content decreased due to the plants roots absorption and leaching to deeper layers, while the NO 3 content in the surfaces layer significantly decreased in the sandy soil. Results showed that equilibrium between the soil solution and the NO 3 content in the solution in porous cups occurred within 8 days. (author)

  6. ROLE OF NUCLEONIC FERMI SURFACE DEPLETION IN NEUTRON STAR COOLING

    Energy Technology Data Exchange (ETDEWEB)

    Dong, J. M.; Zuo, W. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Lombardo, U. [Universita di Catania and Laboratori Nazionali del Sud (INFN), Catania I-95123 (Italy); Zhang, H. F. [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2016-01-20

    The Fermi surface depletion of beta-stable nuclear matter is calculated to study its effects on several physical properties that determine the neutron star (NS) thermal evolution. The neutron and proton Z factors measuring the corresponding Fermi surface depletions are calculated within the Brueckner–Hartree–Fock approach, employing the AV18 two-body force supplemented by a microscopic three-body force. Neutrino emissivity, heat capacity, and in particular neutron {sup 3}PF{sub 2} superfluidity, turn out to be reduced, especially at high baryonic density, to such an extent that the cooling rates of young NSs are significantly slowed.

  7. Doped organic films for OLEDs probed with neutron reflectometry

    International Nuclear Information System (INIS)

    Smith, Arthur R. G.; Lo, Shih-Chun; Gentle, Ian R.

    2009-01-01

    Full text: Conjugated organic semiconductors form an exciting class of materials that can be used in a variety of cutting edge technologies including organic light-emitting diodes, solar cells and transistors. In all these technologies the thin film morphology and interfacial interactions are key areas for their operation. In order to optimise the materials and devices it is critical to understand the structural property relationships for the organic semiconductors by relating the 'molecular' structure to the film morphology and correlating these to the photophysical and device characteristics. Organic light emitting diodes (OLEO) have gained interest for their superior performance compared to current display technologies. Optimising the active emissive layer remains a challenge which can significantly affect the final performance of the device [1]. We have investigated the layering behaviour of small molecule co-evaporated films of deuterated 4,4'-bis(9-carbazolyl)-1, 1 '-biphenyl doped with tris-phenylpyridine iridium(llI) using neutron reflectometry The behaviour of doped emissive layers is dependent on the ratio between dopant and host material. The morphology and internal structure of such films have not yet been investigated, leading to questions about the phase separation and ordering of layers within the film.

  8. Development of a probe by neutron activation for chemical analysis in drillings

    International Nuclear Information System (INIS)

    Baron, J.P.; Carriou, J.; Alexandre, J.; Pinault, J.L.; Dumas, A.; Huet, D.; Collins, V.

    1983-01-01

    Laboratory studies on simulated drillings have been made and compared to calculations on mathematical models. A probe design has been developed with the Laboratory of Ponts et Chaussees. The probe has been tested in-situ on polymetallic sulfide mineralization. The study of the activation gamma allowed to log copper, iron, silicon and potassium. A very feasibility of neutronic activation has been proved during these three years. At the end of this optimization phase, the mining operators will have a device able to give them in real time informations necessary to control their operations [fr

  9. Probing droplets on superhydrophobic surfaces by synchrotron radiation scattering techniques

    KAUST Repository

    Accardo, Angelo

    2014-06-10

    Droplets on artificially structured superhydrophobic surfaces represent quasi contact-free sample environments which can be probed by X-ray microbeams and nanobeams in the absence of obstructing walls. This review will discuss basic surface wettability concepts and introduce the technology of structuring surfaces. Quasi contact-free droplets are compared with contact-free droplets; processes related to deposition and evaporation on solid surfaces are discussed. Droplet coalescence based on the electrowetting effect allows the probing of short-time mixing and reaction processes. The review will show for several materials of biological interest that structural processes related to conformational changes, nucleation and assembly during droplet evaporation can be spatially and temporally resolved by raster-scan diffraction techniques. Orientational ordering of anisotropic materials deposited during solidification at pinning sites facilitates the interpretation of structural data. 2014 International Union of Crystallography.

  10. Probing droplets on superhydrophobic surfaces by synchrotron radiation scattering techniques

    KAUST Repository

    Accardo, Angelo; Di Fabrizio, Enzo M.; Limongi, Tania; Marinaro, Giovanni; Riekel, Christian

    2014-01-01

    Droplets on artificially structured superhydrophobic surfaces represent quasi contact-free sample environments which can be probed by X-ray microbeams and nanobeams in the absence of obstructing walls. This review will discuss basic surface wettability concepts and introduce the technology of structuring surfaces. Quasi contact-free droplets are compared with contact-free droplets; processes related to deposition and evaporation on solid surfaces are discussed. Droplet coalescence based on the electrowetting effect allows the probing of short-time mixing and reaction processes. The review will show for several materials of biological interest that structural processes related to conformational changes, nucleation and assembly during droplet evaporation can be spatially and temporally resolved by raster-scan diffraction techniques. Orientational ordering of anisotropic materials deposited during solidification at pinning sites facilitates the interpretation of structural data. 2014 International Union of Crystallography.

  11. Surface inspection technique with an eddy current testing array probe

    International Nuclear Information System (INIS)

    Nishimizu, Akira; Endo, Hisashi; Tooma, Masahiro; Otani, Kenichi; Ouchi, Hirofumi; Yoshida, Isao; Nonaka, Yoshio

    2010-01-01

    An eddy current testing (ECT) system has been developed for inspecting weld surfaces of components in the reactor pressure vessel of nuclear plants. The system can be applied to curved surfaces with an ECT array probe, it can discriminate flaws from other signal factors by using a combination of arrayed coils signal-phase. The system is applied to a mock-up of core internal components and the signal discrimination using the signal-phase clearly separated flaw and noise signals. (author)

  12. Probing Anisotropic Surface Properties of Molybdenite by Direct Force Measurements.

    Science.gov (United States)

    Lu, Zhenzhen; Liu, Qingxia; Xu, Zhenghe; Zeng, Hongbo

    2015-10-27

    Probing anisotropic surface properties of layer-type mineral is fundamentally important in understanding its surface charge and wettability for a variety of applications. In this study, the surface properties of the face and the edge surfaces of natural molybdenite (MoS2) were investigated by direct surface force measurements using atomic force microscope (AFM). The interaction forces between the AFM tip (Si3N4) and face or edge surface of molybdenite were measured in 10 mM NaCl solutions at various pHs. The force profiles were well-fitted with classical DLVO (Derjaguin-Landau-Verwey-Overbeek) theory to determine the surface potentials of the face and the edge surfaces of molybdenite. The surface potentials of both the face and edge surfaces become more negative with increasing pH. At neutral and alkaline conditions, the edge surface exhibits more negative surface potential than the face surface, which is possibly due to molybdate and hydromolybdate ions on the edge surface. The point of zero charge (PZC) of the edge surface was determined around pH 3 while PZC of the face surface was not observed in the range of pH 3-11. The interaction forces between octadecyltrichlorosilane-treated AFM tip (OTS-tip) and face or edge surface of molybdenite were also measured at various pHs to study the wettability of molybdenite surfaces. An attractive force between the OTS-tip and the face surface was detected. The force profiles were well-fitted by considering DLVO forces and additional hydrophobic force. Our results suggest the hydrophobic feature of the face surface of molybdenite. In contrast, no attractive force between the OTS-tip and the edge surface was detected. This is the first study in directly measuring surface charge and wettability of the pristine face and edge surfaces of molybdenite through surface force measurements.

  13. Measuring the surface-heating of medical ultrasonic probes

    International Nuclear Information System (INIS)

    Kollmann, Chr; Vacariu, G; Fialka-Moser, V; Bergmann, H

    2004-01-01

    Due to converting losses the probe's surface itself is heated up, especially when emitting into air. Possible temperature increases in an ensemble of 15 different diagnostic and therapeutic ultrasound probes from 7 manufacturers in the frequency range between 0.05-7.5 MHz have been examined. Surface temperatures were detected by means of a calibrated IR-thermographic camera using a scheme of various power and pulse settings, as well as different imaging modalitites as used in clinical routine. Depending on the setup and the output power, the absolute surface temperatures of some of the probes emitting in air can be beyond 43 deg. C within 5-7 min.; a maximum surface temperature of 84 deg. C has been detected. Continuous mode or high pulse repetition frequencies on the therapeutic system side, small focused Doppler modes on the diagnostic system side combined with increased emitted acoustic intensities result in high surface temperatures. Within a worst case scenario a potential risk of negative skin changes (heat damage) or non-optimal therapeutic effects seems to be possible if a therapeutic system is used very often and if its emission continues unintentionally. In general the user should be aware that low emission intensities of e.g. 50 mW cm -2 could already produce hot surfaces

  14. Calibration and correction procedures for cosmic-ray neutron soil moisture probes located across Australia

    Science.gov (United States)

    Hawdon, Aaron; McJannet, David; Wallace, Jim

    2014-06-01

    The cosmic-ray probe (CRP) provides continuous estimates of soil moisture over an area of ˜30 ha by counting fast neutrons produced from cosmic rays which are predominantly moderated by water molecules in the soil. This paper describes the setup, measurement correction procedures, and field calibration of CRPs at nine locations across Australia with contrasting soil type, climate, and land cover. These probes form the inaugural Australian CRP network, which is known as CosmOz. CRP measurements require neutron count rates to be corrected for effects of atmospheric pressure, water vapor pressure changes, and variations in incoming neutron intensity. We assess the magnitude and importance of these corrections and present standardized approaches for network-wide analysis. In particular, we present a new approach to correct for incoming neutron intensity variations and test its performance against existing procedures used in other studies. Our field calibration results indicate that a generalized calibration function for relating neutron counts to soil moisture is suitable for all soil types, with the possible exception of very sandy soils with low water content. Using multiple calibration data sets, we demonstrate that the generalized calibration function only applies after accounting for persistent sources of hydrogen in the soil profile. Finally, we demonstrate that by following standardized correction procedures and scaling neutron counting rates of all CRPs to a single reference location, differences in calibrations between sites are related to site biomass. This observation provides a means for estimating biomass at a given location or for deriving coefficients for the calibration function in the absence of field calibration data.

  15. Isolated Neutron Stars: From the Surface to the Interior

    CERN Document Server

    Zane, Silvia; Page, Dany

    2007-01-01

    This book collects the contributions presented at the conference Isolated Neutron Stars: From the Surface to the Interior, held in London in April 2006. Forty years after the discovery of radio pulsars it presents an up-to-date description of the new vision of isolated neutron stars that has emerged in recent years with the advance of multi-wavelength observations. The great variety of isolated neutron stars, from pulsars to magnetars, some of them discovered very recently and many of them not detectable in radio wavelengths, is amply covered by descriptions of recent observational results and presentations of the latest theoretical interpretation of these data.

  16. Neutron Capture Cross Sections of Zr and La: Probing Neutron Exposure and Neutron Flux in Red Giant Stars

    CERN Document Server

    Kitis, G; Wiescher, M; Dahlfors, M; Soares, J

    2002-01-01

    We propose to measure the neutron capture cross sections of $^{139}$La, of $^{93}$Zr (t$_{1/2}$)=1.5 10$^{6}$ yr), and of all the stable Zr isotopes at n_TOF. The aim of these measurements is to improve the accuracy of existing results by at least a factor of three in order to meet the quality required for using the s-process nucleosynthesis as a diagnostic tool for neutron exposure and neutron flux during the He burning stages of stellar evolution. Combining these results with a wealth of recent information coming from high-resolution stellar spectroscopy and from the detailed analysis of presolar dust grains will shed new light on the chemical history of the universe. The investigated cross sections are also needed for technological applications, in particular since $^{93}$Zr is one of the major long-lived fission products.

  17. The influence of surface topography on Kelvin probe force microscopy

    International Nuclear Information System (INIS)

    Sadewasser, S; Leendertz, C; Streicher, F; Lux-Steiner, M Ch

    2009-01-01

    Long-range electrostatic forces govern the imaging mechanism in electrostatic force microscopy as well as in Kelvin probe force microscopy. To improve the analysis of such images, simulations of the electrostatic field distribution have been performed in the past using a flat surface and a cone-shaped tip. However, the electrostatic field distribution between a tip and a sample depends strongly on the surface topography, which has been neglected in previous studies. It is therefore of general importance to study the influence of sample topography features on Kelvin probe force microscopy images, which we address here by performing finite element simulations. We show how the surface potential measurement is influenced by surface steps and surface grooves, considering potential variations in the form of a potential peak and a potential step. The influence of the topography on the measurement of the surface potential is found to be rather small compared to a typical experimental resolution. Surprisingly, in the case of a coinciding topography and potential step an improvement of the potential profile due to the inclusion of the topography is observed. Finally, based on the obtained results, suggestions for the realization of KPFM measurement are given.

  18. Probing Interfacial Processes on Graphene Surface by Mass Detection

    Science.gov (United States)

    Kakenov, Nurbek; Kocabas, Coskun

    2013-03-01

    In this work we studied the mass density of graphene, probed interfacial processes on graphene surface and examined the formation of graphene oxide by mass detection. The graphene layers were synthesized by chemical vapor deposition method on copper foils and transfer-printed on a quartz crystal microbalance (QCM). The mass density of single layer graphene was measured by investigating the mechanical resonance of the QCM. Moreover, we extended the developed technique to probe the binding dynamics of proteins on the surface of graphene, were able to obtain nonspecific binding constant of BSA protein of graphene surface in aqueous solution. The time trace of resonance signal showed that the BSA molecules rapidly saturated by filling the available binding sites on graphene surface. Furthermore, we monitored oxidation of graphene surface under oxygen plasma by tracing the changes of interfacial mass of the graphene controlled by the shifts in Raman spectra. Three regimes were observed the formation of graphene oxide which increases the interfacial mass, the release of carbon dioxide and the removal of small graphene/graphene oxide flakes. Scientific and Technological Research Council of Turkey (TUBITAK) grant no. 110T304, 109T209, Marie Curie International Reintegration Grant (IRG) grant no 256458, Turkish Academy of Science (TUBA-Gebip).

  19. Probing droplets on superhydrophobic surfaces by synchrotron radiation scattering techniques

    Energy Technology Data Exchange (ETDEWEB)

    Accardo, Angelo [Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163 (Italy); Di Fabrizio, Enzo [KAUST (King Abdullah University of Science and Technology), Jeddah (Saudi Arabia); BIONEM Lab at University Magna Graecia, Campus Salvatore Venuta, Viale Europa 88100, Germaneto-Catanzaro (Italy); Limongi, Tania [KAUST (King Abdullah University of Science and Technology), Jeddah (Saudi Arabia); Marinaro, Giovanni [Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163 (Italy); European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex (France); Riekel, Christian, E-mail: riekel@esrf.fr [European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex (France)

    2014-06-10

    A comprehensive review about the use of micro- and nanostructured superhydrophobic surfaces as a tool for in situ X-ray scattering investigations of soft matter and biological materials. Droplets on artificially structured superhydrophobic surfaces represent quasi contact-free sample environments which can be probed by X-ray microbeams and nanobeams in the absence of obstructing walls. This review will discuss basic surface wettability concepts and introduce the technology of structuring surfaces. Quasi contact-free droplets are compared with contact-free droplets; processes related to deposition and evaporation on solid surfaces are discussed. Droplet coalescence based on the electrowetting effect allows the probing of short-time mixing and reaction processes. The review will show for several materials of biological interest that structural processes related to conformational changes, nucleation and assembly during droplet evaporation can be spatially and temporally resolved by raster-scan diffraction techniques. Orientational ordering of anisotropic materials deposited during solidification at pinning sites facilitates the interpretation of structural data.

  20. The microfluidic probe: operation and use for localized surface processing.

    Science.gov (United States)

    Perrault, Cecile M; Qasaimeh, Mohammad A; Juncker, David

    2009-06-04

    Microfluidic devices allow assays to be performed using minute amounts of sample and have recently been used to control the microenvironment of cells. Microfluidics is commonly associated with closed microchannels which limit their use to samples that can be introduced, and cultured in the case of cells, within a confined volume. On the other hand, micropipetting system have been used to locally perfuse cells and surfaces, notably using push-pull setups where one pipette acts as source and the other one as sink, but the confinement of the flow is difficult in three dimensions. Furthermore, pipettes are fragile and difficult to position and hence are used in static configuration only. The microfluidic probe (MFP) circumvents the constraints imposed by the construction of closed microfluidic channels and instead of enclosing the sample into the microfluidic system, the microfluidic flow can be directly delivered onto the sample, and scanned across the sample, using the MFP. . The injection and aspiration openings are located within a few tens of micrometers of one another so that a microjet injected into the gap is confined by the hydrodynamic forces of the surrounding liquid and entirely aspirated back into the other opening. The microjet can be flushed across the substrate surface and provides a precise tool for localized deposition/delivery of reagents which can be used over large areas by scanning the probe across the surface. In this video we present the microfluidic probe (MFP). We explain in detail how to assemble the MFP, mount it atop an inverted microscope, and align it relative to the substrate surface, and finally show how to use it to process a substrate surface immersed in a buffer.

  1. Neutron radiography of aircraft composite flight control surfaces

    International Nuclear Information System (INIS)

    Lewis, W.J.; Bennett, L.G.I.; Chalovich, T.R.; Francescone, O.

    2001-01-01

    A small (20 kWth), safe, pool-type nuclear research reactor called the SLOWPOKE-2 is located at the Royal Military College of Canada (RMC). The reactor was originally installed for teaching, training, research and semi-routine analysis, specifically, neutron activation analysis. It was envisioned that the neutrons from the SLOWPOKE-2 could also be used for neutron radiography, and so a research program was initiated to develop this technology. Over a period of approximately 15 years, and through a series of successive modifications, a neutron radiography system (NRS) was developed. Once completed, several applications of the technology have been demonstrated, including the nondestructive examination of the composite flight control surfaces from the Canadian Air Force's primary jet fighter, the CF18 Hornet aircraft. An initial trial was setup to investigate the flight control surfaces of 3 aircraft, to determine the parameters for a final licensed system, and to compare the results to other nondestructive methods. Over 500 neutron radiographs were made for these first 3 aircraft, and moisture and corrosion were discovered in the honeycomb structure and hydration was found in the composite and adhesive layers. In comparison with other NDT methods, neutron radiography was the only method that could detect the small areas of corrosion and moisture entrapment. However, before examining an additional 7 aircraft, the recommended modifications to the NRS were undertaken. These modifications were necessary to accommodate the larger flight control surfaces safely by incorporating flexible conformable shielding. As well, to expedite inspections so that all flight control surfaces from one aircraft could be completed in less than two weeks, there was a need to decrease the exposure time by both faster film/conversion screen combinations and by incorporating the capability of near realtime, digital radioscopy. Finally, as there are no inspection specific image quality

  2. Grain boundary segregation in neutron-irradiated 304 stainless steel studied by atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Toyama, T., E-mail: ttoyama@imr.tohoku.ac.jp [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Nozawa, Y. [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Van Renterghem, W. [SCK Bullet CEN, Nuclear Materials Science Institute, Boeretang 200, 2400 Mol (Belgium); Matsukawa, Y.; Hatakeyama, M.; Nagai, Y. [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Al Mazouzi, A. [EDF R and D, Avenue des Renardieres Ecuelles, 77818 Moret sur Loing Cedex (France); Van Dyck, S. [SCK Bullet CEN, Nuclear Materials Science Institute, Boeretang 200, 2400 Mol (Belgium)

    2012-06-15

    Radiation-induced segregation (RIS) of solute atoms at a grain boundary (GB) in 304 stainless steel (SS), neutron-irradiated to a dose of 24 dpa at 300 Degree-Sign C in the fuel wrapper plates of a commercial pressurized water reactor, was investigated using laser-assisted atom probe tomography (APT). Ni, Si, and P enrichment and Cr and Fe depletion at the GB were evident. The full-width at half-maximum of the RIS region was {approx}3 nm for the concentration profile peaks of Ni and Si. The atomic percentages of Ni, Si, and Cr at the GB were {approx}19%, {approx}7%, and {approx}14%, respectively, in agreement with previously-reported values for neutron-irradiated SS. A high number density of intra-granular Ni-Si rich precipitates formed in the matrix. A precipitate-denuded zone with a width of {approx}10 nm appeared on both sides of the GB.

  3. Probing Extreme-density Matter with Gravitational-wave Observations of Binary Neutron Star Merger Remnants

    Energy Technology Data Exchange (ETDEWEB)

    Radice, David [Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ 08540 (United States); Bernuzzi, Sebastiano [Department of Mathematical, Physical and Computer Sciences, University of Parma, I-43124 Parma (Italy); Pozzo, Walter Del [Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Pisa I-56127 (Italy); Roberts, Luke F. [NSCL/FRIB and Department of Physics and Astronomy, Michigan State University, 640 S Shaw Lane, East Lansing, MI 48824 (United States); Ott, Christian D. [TAPIR, Walter Burke Institute for Theoretical Physics, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125 (United States)

    2017-06-20

    We present a proof-of-concept study, based on numerical-relativity simulations, of how gravitational waves (GWs) from neutron star merger remnants can probe the nature of matter at extreme densities. Phase transitions and extra degrees of freedom can emerge at densities beyond those reached during the inspiral, and typically result in a softening of the equation of state (EOS). We show that such physical effects change the qualitative dynamics of the remnant evolution, but they are not identifiable as a signature in the GW frequency, with the exception of possible black hole formation effects. The EOS softening is, instead, encoded in the GW luminosity and phase and is in principle detectable up to distances of the order of several megaparsecs with advanced detectors and up to hundreds of megaparsecs with third-generation detectors. Probing extreme-density matter will require going beyond the current paradigm and developing a more holistic strategy for modeling and analyzing postmerger GW signals.

  4. Probing Extreme-density Matter with Gravitational-wave Observations of Binary Neutron Star Merger Remnants

    International Nuclear Information System (INIS)

    Radice, David; Bernuzzi, Sebastiano; Pozzo, Walter Del; Roberts, Luke F.; Ott, Christian D.

    2017-01-01

    We present a proof-of-concept study, based on numerical-relativity simulations, of how gravitational waves (GWs) from neutron star merger remnants can probe the nature of matter at extreme densities. Phase transitions and extra degrees of freedom can emerge at densities beyond those reached during the inspiral, and typically result in a softening of the equation of state (EOS). We show that such physical effects change the qualitative dynamics of the remnant evolution, but they are not identifiable as a signature in the GW frequency, with the exception of possible black hole formation effects. The EOS softening is, instead, encoded in the GW luminosity and phase and is in principle detectable up to distances of the order of several megaparsecs with advanced detectors and up to hundreds of megaparsecs with third-generation detectors. Probing extreme-density matter will require going beyond the current paradigm and developing a more holistic strategy for modeling and analyzing postmerger GW signals.

  5. Probing Free-Energy Surfaces with Differential Scanning Calorimetry

    Science.gov (United States)

    Sanchez-Ruiz, Jose M.

    2011-05-01

    Many aspects of protein folding can be understood in terms of projections of the highly dimensional energy landscape onto a few (or even only one) particularly relevant coordinates. These free-energy surfaces can be probed conveniently from experimental differential scanning calorimetry (DSC) thermograms, as DSC provides a direct relation with the protein partition function. Free-energy surfaces thus obtained are consistent with two fundamental scenarios predicted by the energy-landscape perspective: (a) well-defined macrostates separated by significant free-energy barriers, in some cases, and, in many other cases, (b) marginal or even vanishingly small barriers, which furthermore show a good correlation with kinetics for fast- and ultrafast-folding proteins. Overall, the potential of DSC to assess free-energy surfaces for a wide variety of proteins makes it possible to address fundamental issues, such as the molecular basis of the barrier modulations produced by natural selection in response to functional requirements or to ensure kinetic stability.

  6. Portable gamma and thermal neutron probe using a 6LiI(Eu) crystal

    International Nuclear Information System (INIS)

    Carneiro, Clemente J.G.; Araujo, Geraldo P.; Milian, Felix M.; Barbosa, Jurandir C.; Garcia, Fermin; Oliveira, Arno H.; Silva, Mario R.S.; Penna, Rodrigo

    2011-01-01

    Europium-activated lithium-6 iodide is a scintillator used for gamma and neutron counting. A portable detection system was built based on this scintillator. This system has three modules: the scintillator, a 10 m liquid light guide, and a Hamamatsu photon counting head H9319 used as a light pulse digitizer. Data transfer, measurement time and other necessary adjustment can be controlled by software from the PC through the RS-232C interface. The scintillator, a crystal of 6 LiI(Eu), is a small cylinder with 3 mm diameter and 40 mm length completely sealed in an aluminum tube coupled to the light guide. The small size of the scintillator increases the neutron/gamma count ratio, since 2 to 3 mm of thickness of this crystal absorbs all thermal neutrons. Intensities of X and gamma rays, and thermal neutrons can be recorded for time intervals of 10 ms to 1 s storing up to 10000 countings. The system was calibrated for measuring radiation doses for validating numerical models in dosimetry. Two characteristic reinforce this application, measurements can be done at several meters away from the radiation source and also inside of water. In addition, it was used to build nuclear probes based on Compton scattering or neutron moderation in porous media by attaching an AmBe source to the top of the aluminum tube. Tests were done to determine the reproducibility of counting rates. Background counting was measured at several temperatures to verify the influence of dark current of PMT. Sealed AmBe, low activity Am, and X rays sources were used for studies of radiation counting statistics. X rays apparatus was used to correlate counting rates measured with the 6 LiI(Eu) detection system and doses measured with an ionization chamber at several distances from the X ray source. (author)

  7. Portable gamma and thermal neutron probe using a {sup 6}LiI(Eu) crystal

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, Clemente J.G.; Araujo, Geraldo P.; Milian, Felix M.; Barbosa, Jurandir C.; Garcia, Fermin [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil). Centro de Pesquisas em Ciencias e Tecnologias das Radiacoes (CPqCTR); Oliveira, Arno H.; Silva, Mario R.S.; Penna, Rodrigo [Universidade Federal de Minas Gerais (DEN-UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Nuclear

    2011-07-01

    Europium-activated lithium-6 iodide is a scintillator used for gamma and neutron counting. A portable detection system was built based on this scintillator. This system has three modules: the scintillator, a 10 m liquid light guide, and a Hamamatsu photon counting head H9319 used as a light pulse digitizer. Data transfer, measurement time and other necessary adjustment can be controlled by software from the PC through the RS-232C interface. The scintillator, a crystal of {sup 6}LiI(Eu), is a small cylinder with 3 mm diameter and 40 mm length completely sealed in an aluminum tube coupled to the light guide. The small size of the scintillator increases the neutron/gamma count ratio, since 2 to 3 mm of thickness of this crystal absorbs all thermal neutrons. Intensities of X and gamma rays, and thermal neutrons can be recorded for time intervals of 10 ms to 1 s storing up to 10000 countings. The system was calibrated for measuring radiation doses for validating numerical models in dosimetry. Two characteristic reinforce this application, measurements can be done at several meters away from the radiation source and also inside of water. In addition, it was used to build nuclear probes based on Compton scattering or neutron moderation in porous media by attaching an AmBe source to the top of the aluminum tube. Tests were done to determine the reproducibility of counting rates. Background counting was measured at several temperatures to verify the influence of dark current of PMT. Sealed AmBe, low activity Am, and X rays sources were used for studies of radiation counting statistics. X rays apparatus was used to correlate counting rates measured with the {sup 6}LiI(Eu) detection system and doses measured with an ionization chamber at several distances from the X ray source. (author)

  8. Use of Neutron Probe to Quantify the Soil Moisture Flux in Layers of Cultivated Soil by Chickpea

    International Nuclear Information System (INIS)

    El- Gendy, R.W.

    2008-01-01

    This work aims to use the neutron moisture meter and the soil moisture retention curve to quantify the soil moisture flux in the soil profile of Nubarria soil in Egypt at 15, 30, 45, and 60-cm depths during the growth season of Chickpea. This method depends on the use of in situ θ measurements via neutron moisture meter and soil matric suction using model of the soil moisture retention curve at different soil depths, which can be determined in situ. Total hydraulic potential values at the different soil depths were calculated as a function (θ) using the derivative model. The gradient of hydraulic potential at any soil depth can be obtained by detecting of the hydraulic potential within the soil profile. The soil water fluxes at the different soil depths were calculated using In situ measured unsaturated hydraulic conductivity and the gradient of hydraulic potential, which correlated with soil moisture contents as measured by neutron probe. Values of hydraulic potentials after and before irrigation indicate that the direction of soil moisture movement was downward after irrigation and was different before next irrigation. Collecting active roots for water absorption of chickpea were defined from direction of soil water movement from up and down to a certain soil depth was 19 cm depth from the soil surface. Active rooting depth was 53 cm depth, which separates between evapotranspiration and gravity effects The soil water fluxes after and before the next irrigation of chickpea were 1.2453, 0.8613, 0.8197 and 0.6588 cm/hr and 0.0037, - 0.0270,- 0.1341, and 0.2545 cm/hr at 15, 30, 45 and 60 cm depths, respectively. The negative values at 30 and 45 cm depth before the next irrigation indicates there were up ward movement for soil water flux, where finding collecting active roots for water absorption of chickpea at 19 cm depth. Direction of soil water movement, soil water flux, collecting active roots for water absorption and active rooting depth can be determined using

  9. Probing dielectric ceramics surface at sub-micrometer scale

    Energy Technology Data Exchange (ETDEWEB)

    Fiorenza, Patrick; Lo Nigro, Raffaella; Raineri, Vito [Istituto per la Microelettronica e Microsistemi, Consiglio Nazionale delle Ricerche, Stradale Primosole 50, 95121 Catania (Italy); Schmidt, Rainer; Sinclair, Derek C, E-mail: patrick.fiorenza@imm.cnr.it [Department of Engineering Materials, Sir Robert Hadfield Building, University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom)

    2010-02-15

    Scanning probe microscopy (SPM) with conductive tips has been used to image the dielectric properties of ceramics with giant permittivity. In particular, measurements in impedance mode of local resistivity allowed to image the permittivity map on polycrystalline materials. Such imaging provides correlation between the dielectric properties and the sample structure, in particular focusing on defects inside the single grains. Great attention has been devoted to the possible artefacts due to surface imperfections, such as huge roughness and/or contamination. A reliable surface investigation has been obtained after the definition of both the physical and geometrical criteria to avoid the artefacts due to both the surface or anomalous tip-sample contact area variation (for instance, in grain boundaries, holes and cracks in the ceramic pills). In particular, the power spectral density (PSD) allows to get access to the different periodic components of the surface roughness. The PSD demonstrated to be a sensitive tool to check the surface conditions after the polishing procedures aimed to the progressive decreasing of surface roughness, in order to reach the SPM limits and to avoid artefacts inducing wrong data interpretation.

  10. A scanning fluid dynamic gauging technique for probing surface layers

    International Nuclear Information System (INIS)

    Gordon, Patrick W; Chew, Y M John; Wilson, D Ian; Brooker, Anju D M; York, David W

    2010-01-01

    Fluid dynamic gauging (FDG) is a technique for measuring the thickness of soft solid deposit layers immersed in a liquid environment, in situ and in real time. This paper details the performance of a novel automated, scanning FDG probe (sFDG) which allows the thickness of a sample layer to be monitored at several points during an experiment, with a resolution of ±5 µm. Its application is demonstrated using layers of gelatine, polyvinyl alcohol (PVA) and baked tomato purée deposits. Swelling kinetics, as well as deformation behaviour—based on knowledge of the stresses imposed on the surface by the gauging flow—can be determined at several points, affording improved experimental data. The use of FDG as a surface scanning technique, operating as a fluid mechanical analogue of atomic force microscopy on a millimetre length scale, is also demonstrated. The measurement relies only on the flow behaviour, and is thus suitable for use in opaque fluids, does not contact the surface itself and does not rely on any specific physical properties of the surface, provided it is locally stiff

  11. Substrate texture properties induce triatomine probing on bitten warm surfaces

    Directory of Open Access Journals (Sweden)

    Lorenzo Marcelo G

    2011-06-01

    Full Text Available Abstract Background In this work we initially evaluated whether the biting process of Rhodnius prolixus relies on the detection of mechanical properties of the substrate. A linear thermal source was used to simulate the presence of a blood vessel under the skin of a host. This apparatus consisted of an aluminium plate and a nickel-chrome wire, both thermostatized and presented at 33 and 36°C, respectively. To evaluate whether mechanical properties of the substrate affect the biting behaviour of bugs, this apparatus was covered by a latex membrane. Additionally, we evaluated whether the expression of probing depends on the integration of bilateral thermal inputs from the antennae. Results The presence of a latex cover on a thermal source induced a change in the biting pattern shown by bugs. In fact, with latex covered sources it was possible to observe long bites that were never performed in response to warm metal surfaces. The total number of bites was higher in intact versus unilaterally antennectomized insects. These bites were significantly longer in intact than in unilaterally antennectomized insects. Conclusions Our results suggest that substrate recognition by simultaneous input through thermal and mechanical modalities is required for triggering maxillary probing activity.

  12. Nuclear reactor vessel surface inspecting technique applying electric resistance probe

    International Nuclear Information System (INIS)

    Yamaguchi, T.; Enami, K.; Yoshioka, M.

    1975-01-01

    A new technique for inspecting the inner surface of the PWR type nuclear reactor vessel by use of an electric resistance probe is introduced, centering on a data processing system. This system is composed of a mini-computer, a system typewriter, an interface unit, a D-A converter and controller, and X-Y recorder and others. Its functions are judging flaws and making flaw detection maps. In order to judge flaws by flaw detection signals, three kinds of flaw judging methods have been developed. In case there is a flaw, its position and depth are calculated and listed on the system typewriter. The flaw detection maps are expressed in four kinds of modes and they are displayed on the X-Y recorder. (auth.)

  13. Quantitatively Probing the Means of Controlling Nanoparticle Assembly on Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Patete, J.m.; Wong, S.; Peng, X.; Serafin, J.M.

    2011-05-17

    As a means of developing a simple, cost-effective, and reliable method for probing nanoparticle behavior, we have used atomic force microscopy to gain a quantitative 3D visual representation of the deposition patterns of citrate-capped Au nanoparticles on a substrate as a function of (a) sample preparation, (b) the choice of substrate, (c) the dispersion solvent, and (d) the number of loading steps. Specifically, we have found that all four parameters can be independently controlled and manipulated in order to alter the resulting pattern and quantity of as-deposited nanoparticles. From these data, the sample preparation technique appears to influence deposition patterns most broadly, and the dispersion solvent is the most convenient parameter to use in tuning the quantity of nanoparticles deposited onto the surface under spin-coating conditions. Indeed, we have quantitatively measured the effect of surface coverage for both mica and silicon substrates under preparation techniques associated with (i) evaporation under ambient air, (ii) heat treatment, and (iii) spin-coating preparation conditions. In addition, we have observed a decrease in nanoparticle adhesion to a substrate when the ethylene glycol content of the colloidal dispersion solvent is increased, which had the effect of decreasing interparticle-substrate interactions. Finally, we have shown that substrates prepared by these diverse techniques have potential applicability in surface-enhanced Raman spectroscopy.

  14. Quantitatively Probing the Means of Controlling Nanoparticle Assembly on Surfaces

    International Nuclear Information System (INIS)

    Patete, J.M.; Wong, S.; Peng, X.; Serafin, J.M.

    2011-01-01

    As a means of developing a simple, cost-effective, and reliable method for probing nanoparticle behavior, we have used atomic force microscopy to gain a quantitative 3D visual representation of the deposition patterns of citrate-capped Au nanoparticles on a substrate as a function of (a) sample preparation, (b) the choice of substrate, (c) the dispersion solvent, and (d) the number of loading steps. Specifically, we have found that all four parameters can be independently controlled and manipulated in order to alter the resulting pattern and quantity of as-deposited nanoparticles. From these data, the sample preparation technique appears to influence deposition patterns most broadly, and the dispersion solvent is the most convenient parameter to use in tuning the quantity of nanoparticles deposited onto the surface under spin-coating conditions. Indeed, we have quantitatively measured the effect of surface coverage for both mica and silicon substrates under preparation techniques associated with (i) evaporation under ambient air, (ii) heat treatment, and (iii) spin-coating preparation conditions. In addition, we have observed a decrease in nanoparticle adhesion to a substrate when the ethylene glycol content of the colloidal dispersion solvent is increased, which had the effect of decreasing interparticle-substrate interactions. Finally, we have shown that substrates prepared by these diverse techniques have potential applicability in surface-enhanced Raman spectroscopy.

  15. Monovacancy paramagnetism in neutron-irradiated graphite probed by 13C NMR.

    Science.gov (United States)

    Zhang, Z T; Xu, C; Dmytriieva, D; Molatta, S; Wosnitza, J; Wang, Y T; Helm, M; Zhou, Shengqiang; Kühne, H

    2017-10-20

    We report on the magnetic properties of monovacancy defects in neutron-irradiated graphite, probed by 13 C nuclear magnetic resonance spectroscopy. The bulk paramagnetism of the defect moments is revealed by the temperature dependence of the NMR frequency shift and spectral linewidth, both of which follow a Curie behavior, in agreement with measurements of the macroscopic magnetization. Compared to pristine graphite, the fluctuating hyperfine fields generated by the defect moments lead to an enhancement of the 13 C nuclear spin-lattice relaxation rate [Formula: see text] by about two orders of magnitude. With an applied magnetic field of 7.1 T, the temperature dependence of [Formula: see text] below about 10 K can well be described by a thermally activated form, [Formula: see text], yielding a singular Zeeman energy of ([Formula: see text]) meV, in excellent agreement with the sole presence of polarized, non-interacting defect moments.

  16. Weak magnetism of Aurivillius-type multiferroic thin films probed by polarized neutron reflectivity

    Science.gov (United States)

    Zhai, Xiaofang; Grutter, Alexander J.; Yun, Yu; Cui, Zhangzhang; Lu, Yalin

    2018-04-01

    Unambiguous magnetic characterization of room-temperature multiferroic materials remains challenging due in part to the difficulty of distinguishing their very weak ferromagnetism from magnetic impurity phases and other contaminants. In this study, we used polarized neutron reflectivity to probe the magnetization of B i6FeCoT i3O18 and LaB i5FeCoT i3O18 in their epitaxial thin films while eliminating a variety of impurity contributions. Our results show that LaB i5FeCoT i3O18 exhibits a magnetization of about 0.016 ±0.027 μB/Fe -Co pair at room temperature, while the B i6FeCoT i3O18 thin film only exhibits a weak magnetic moment below room temperature, with a saturation magnetization of 0.049 ±0.015 μB/Fe -Co pair at 50 K. This polarized-neutron-reflectivity study places an upper magnetization limit on the matrix material of the magnetically doped Aurivillius oxides and helps to clarify the true mechanism behind the room-temperature magnetic performance.

  17. Assessment of the geometric coincidence of neutron and gamma probe measurements with solo 40 and CPN 501 B

    International Nuclear Information System (INIS)

    Valles, V.; Guiresse, M.; Tcherbakov, R.

    1989-01-01

    The distance between the gamma and neutron probe measurement centres was determined for the Nardeux Solo 40 and CPN 501 B probes. The centre of the spheres of influence was localized using a water-air interface constituted by a metal cylinder filled with 200 liters of water. For Solo 40, the discrepancy between the two measurement centres was 6 cm. This shift value, which is quite acceptable, does not require any correction for these measurements, even when the soil is heterogeneous. For CNP 501 B, the discrepancy between the neutron and gamma measurement was 11 cm, i.e. nearly twice the value observed with Solo 40. In soils with a marked vertical heterogeneity, it therefore seems preferable to operate a 11 cm shift of the probe between the moisture and density measurements [fr

  18. Mathematical model and computer programme for theoretical calculation of calibration curves of neutron soil moisture probes with highly effective counters

    International Nuclear Information System (INIS)

    Kolev, N.A.

    1981-07-01

    A mathematical model based on the three group theory for theoretical calculation by means of computer of the calibration curves of neutron soil moisture probes with highly effective counters, is described. Methods for experimental correction of the mathematical model are discussed and proposed. The computer programme described allows the calibration of neutron probes with high or low effective counters, and central or end geometry, with or without linearizing of the calibration curve. The use of two calculation variants and printing of output data gives the possibility not only for calibration, but also for other researches. The separate data inputs for soil and probe temperature allow the temperature influence analysis. The computer programme and calculation examples are given. (author)

  19. On the control of irrigation through soil moisture measurement using a neutron depth probe in horizontal subsurface measuring circuits

    International Nuclear Information System (INIS)

    Schaecke, B.; Schaecke, E.

    1977-01-01

    An outline is given of the advantages inherent in soil moisture measurement by means of a neutron probe in horizontal subsurface measuring circuits for irrigation control. Preliminary experience for the setting up of a field calibration curve and for practical measurement are submitted. This technique includes the following advantages: almost complete covering of the upper soil range which is of interest to irrigation control; good measuring density; suitable distribution of measuring points per unit area; possibility of continuous probe passage; optimal repeatability of measurements; exploration of a unit area with but few measuring circuits; no obstacles to tillage, drilling, intercultivation and harvest operations; and complete conservation of crop and plot which is not reached with any other soil moisture measurement technique so far available. Making use of the above advantages, the new technique allows automatic irrigation control with only one neutron depth probe. (author)

  20. Probing the hydration water diffusion of macromolecular surfaces and interfaces

    International Nuclear Information System (INIS)

    Ortony, Julia H; Cheng, Chi-Yuan; Franck, John M; Pavlova, Anna; Hunt, Jasmine; Han, Songi; Kausik, Ravinath

    2011-01-01

    We probe the translational dynamics of the hydration water surrounding the macromolecular surfaces of selected polyelectrolytes, lipid vesicles and intrinsically disordered proteins with site specificity in aqueous solutions. These measurements are made possible by the recent development of a new instrumental and methodological approach based on Overhauser dynamic nuclear polarization (DNP)-enhanced nuclear magnetic resonance (NMR) spectroscopy. This technique selectively amplifies 1 H NMR signals of hydration water around a spin label that is attached to a molecular site of interest. The selective 1 H NMR amplification within molecular length scales of a spin label is achieved by utilizing short-distance range (∼r -3 ) magnetic dipolar interactions between the 1 H spin of water and the electron spin of a nitroxide radical-based label. Key features include the fact that only minute quantities (<10 μl) and dilute (≥100 μM) sample concentrations are needed. There is no size limit on the macromolecule or molecular assembly to be analyzed. Hydration water with translational correlation times between 10 and 800 ps is measured within ∼10 A distance of the spin label, encompassing the typical thickness of a hydration layer with three water molecules across. The hydration water moving within this time scale has significant implications, as this is what is modulated whenever macromolecules or molecular assemblies undergo interactions, binding or conformational changes. We demonstrate, with the examples of polymer complexation, protein aggregation and lipid-polymer interaction, that the measurements of interfacial hydration dynamics can sensitively and site specifically probe macromolecular interactions.

  1. Electrical conduction through surface superstructures measured by microscopic four-point probes

    DEFF Research Database (Denmark)

    Hasegawa, S.; Shiraki, I.; Tanabe, F.

    2003-01-01

    For in-situ measurements of the local electrical conductivity of well-defined crystal surfaces in ultra-high vacuum, we have developed two kinds of microscopic four-point probe methods. One involves a "four-tip STM prober," in which four independently driven tips of a scanning tunneling microscope...... (STM) are used for measurements of four-point probe conductivity. The probe spacing can be changed from 500 nm to 1 mm. The other method involves monolithic micro-four-point probes, fabricated on silicon chips, whose probe spacing is fixed around several mum. These probes are installed in scanning...

  2. Profile measurement of a bent neutron mirror using an ultrahigh precision non-contact measurement system with an auto focus laser probe

    International Nuclear Information System (INIS)

    Morita, S; Guo, J; Yamagata, Y; Yamada, N L; Torikai, N; Takeda, S; Furusaka, M

    2016-01-01

    A bent neutron mirror has been considered as one of the best solutions for focusing neutron beams from the viewpoint of cost-benefit performance. Although the form deviation of the bent profile is expected because of the large spot size, it is difficult to measure due to its geometric limitation. Here, we propose a non-contact measurement system using an auto focus (AF) laser probe on an ultrahigh precision machine tool to precisely evaluate the form deviation of the bent mirror. The AF laser probe is composed of a diode laser, a position sensitive sensor, a charge-coupled device (CCD) camera and a microscope objective lens which is actuated by an electromagnetic motor with 1 nm resolution for position sensing and control. The sensor enables a non-contact profile measurement of a high precision surface without any surface damage in contrast with contact-type ultrahigh precision coordinate measurement machines with ruby styli. In the on-machine measurement system, a personal computer simultaneously acquires a displacement signal from the AF laser probe and 3-axis positional coordinates of the ultrahigh machine tool branched between the linear laser scales and the numerical controller. The acquisition rate of the 4-axis positional data in 1 nm resolution is more than 10 Hz and the simultaneity between the axes is negligible. The profile of a neutron bent mirror was measured from a transparent side using the developed system, and the result proves that the form deviation of the mirror enlarged the the spot size of focused neuron beam. (paper)

  3. Probing the magnetic profile of diluted magnetic semiconductors using polarized neutron reflectivity.

    Science.gov (United States)

    Luo, X; Tseng, L T; Lee, W T; Tan, T T; Bao, N N; Liu, R; Ding, J; Li, S; Lauter, V; Yi, J B

    2017-07-24

    Room temperature ferromagnetism has been observed in the Cu doped ZnO films deposited under an oxygen partial pressure of 10 -3 and 10 -5 torr on Pt (200 nm)/Ti (45 nm)/Si (001) substrates using pulsed laser deposition. Due to the deposition at relatively high temperature (873 K), Cu and Ti atoms diffuse to the surface and interface, which significantly affects the magnetic properties. Depth sensitive polarized neutron reflectometry method provides the details of the composition and magnetization profiles and shows that an accumulation of Cu on the surface leads to an increase in the magnetization near the surface. Our results reveal that the presence of the copper at Zn sites induces ferromagnetism at room temperature, confirming intrinsic ferromagnetism.

  4. Use of Tesla NZK 203 neutron probe in studying water as geochemical factor in weathering zone

    International Nuclear Information System (INIS)

    Hally, J.

    1980-01-01

    The Tesla NZK 203 neutron moisture gage was used for determining soil moisture in depths of 1 and 2 meters in the Luha-Kacerov profile in the Zelivka water reservoir basin. The borehole spacing was 100 m. Measurements were made once a month between May and October 1978. The results were compared with the granulometric composition and the values of the specific surface areas of earths in the area. The Tesla NZK 203 moisture gage was fully proven for speedy measurement of volume moisture at constant measuring points. (Ha)

  5. Neutron activation analysis of small particles brought back from the asteroid Itokawa by the space probe Hayabusa

    International Nuclear Information System (INIS)

    Ebihara, Mitsuru

    2013-01-01

    The probe in the title launched in May 2003, landed on the asteroid 25143 (Itokawa) to collect the surface material, and returned to the desert of Australia in June 2010. The material carried in Japan Aerospace Exploration Agency (JAXA) was found to be >1,500 particles of extraterrestrial origin. This paper reports the results of activation analysis of a part of particles for the purpose of characterizing the elemental composition. The size of particles was mostly <100 mc-m and the mass, several 10s mc-g. The experiment was performed preliminarily on Kilabo meteorite using Kyoto University Research Reactor (KURR) as a neutron source, and then on 1 Itokawa particle named RA-QD02-0049, which was activated for 19 hr. The cooled particle was found to be split mainly in 2 parts (0049-1 and -2), which were subjected to analysis of gamma ray with Ge semiconductor detector in the KURR Institute and Kanazawa University. Analysis revealed that the 2 particles contained 8 elements of Na, Sc, Cr, Fe, Co, Ni, Zn and Ir, which were then quantitated with similarly neutron irradiated Allende meteorite, basalt JB-1 and highly purified Fe, and with previous findings by scanning electron microscope with energy dispersive X-ray spectrometer (SEM-EDX) showing the Itokawa particle was an olivine. Finally, 0049-1 and -2 were found to be of mass of 1.6 and 1.5 mc-g, respectively, based on which the calculated contents of the 8 elements revealed that they were homogeneously existed in the Itokawa particle. Comparison of elemental composition of the particle with those of various intra- and extra-terrestrial rocks and meteorites suggested that Itokawa had a feature of elements aggregated at the early stage after formation of the solar system 4.5 billion years ago. (T.T.)

  6. Microfour-point probe for studying electronic transport through surface states

    DEFF Research Database (Denmark)

    Petersen, Christian Leth; Grey, Francois; Shiraki, I.

    2000-01-01

    Microfour-point probes integrated on silicon chips have been fabricated with probe spacings in the range 4-60 mum. They provide a simple robust device for electrical transport measurements at surfaces, bridging the gap between conventional macroscopic four-point probes and scanning tunneling...... transport through surface states, which is not observed on the macroscopic scale, presumably due to scattering at atomic steps. (C) 2000 American Institute of Physics....

  7. Direct measurement of surface-state conductance by microscopic four-point probe method

    DEFF Research Database (Denmark)

    Hasegawa, S.; Shiraki, I.; Tanikawa, T.

    2002-01-01

    For in situ measurements of local electrical conductivity of well defined crystal surfaces in ultrahigh vacuum, we have developed microscopic four-point probes with a probe spacing of several micrometres, installed in a scanning-electron - microscope/electron-diffraction chamber. The probe...... is precisely positioned on targeted areas of the sample surface by using piezoactuators. This apparatus enables conductivity measurement with extremely high surface sensitivity, resulting in direct access to surface-state conductivity of the surface superstructures, and clarifying the influence of atomic steps...

  8. Polycrystalline semiconductor probes for monitoring the density distribution of an intense thermal neutron flux in nuclear reactors

    International Nuclear Information System (INIS)

    Graul, J.; Mueller, R.G.; Wagner, E.

    1975-05-01

    The applicability of semiconductor detectors for high thermal neutron flux densities is theoretically estimated and experimentally examined. For good thermal stability and low radiation capture rate silicon carbide is used as semiconductor material, produced in polycristalline layers to achieve high radiation resistance. The relations between crystallinity, photoelectric sensitivity and radiation resistance are shown. The radiation resistance of polycrystalline SiC-probes is approximately 100 times greater than that of conventional single crystal radiation detectors. For thermal neutron measurement they can be used in the flux range of approx. 10 10 13 (cm -2 sec -1 ) with operation times of 1.6 a >= tsub(b,max) >= 30 d, resp. (orig.) [de

  9. Perceiving the vertical distances of surfaces by means of a hand-held probe.

    Science.gov (United States)

    Chan, T C; Turvey, M T

    1991-05-01

    Nine experiments were conducted on the haptic capacity of people to perceive the distances of horizontal surfaces solely on the basis of mechanical stimulation resulting from contacting the surfaces with a vertically held rod. Participants touched target surfaces with rods inside a wooden cabinet and reported the perceived surface location with an indicator outside the cabinet. The target surface, rod, and the participant's hand were occluded, and the sound produced in exploration was muffled. Properties of the probe (length, mass, moment of inertia, center of mass, and shape) were manipulated, along with surface distance and the method and angle of probing. Results suggest that for the most common method of probing, namely, tapping, perceived vertical distance is specific to a particular relation among the rotational inertia of the probe, the distance of the point of contact with the surface from the probe's center of percussion, and the inclination at contact of the probe to the surface. They also suggest that the probe length and the distance probed are independently perceivable. The results were discussed in terms of information specificity versus percept-percept coupling and parallels between selective attention in haptic and visual perception.

  10. Correlation of DT and DD fusion neutron damage in silicon surface barrier detector

    International Nuclear Information System (INIS)

    Iida, Toshiyuki; Sueyoshi, Yasuhiro; Sunarno; Takahashi, Akito

    1994-01-01

    In order to examine the correlation of DT and DD fusion neutron damage in Si, a silicon surface barrier detector (Si-SBD) was irradiation with neutrons from a deuteron accelerator. The leakage current increased proportionally with neutron fluence, which determined the neutron damage constant for the Si-SBD. The correlation factor of the DT and DD neutron damage in the Si-SBD was determined from the ratio of the DT and DD neutron damage constants and was found to be 2.3. We also calculated the rate of DT and DD neutron displacement damage for Si by using the TRIM-90 computer program and actual data on neutron reactions in the Si-SBD. The correlation factor of DT and DD neutron damage from the calculation agreed with that from the Si-SBD irradiation experiment. (author)

  11. Excitation of surface waves of ultracold neutrons on absorbing trap walls as anomalous loss factor

    International Nuclear Information System (INIS)

    Bokun, R.Ch.

    2006-01-01

    One analyzed probability of excitation of surface waves of ultracold neutrons in terms of a plane model consisting of three media: vacuum, a finite depth neutron absorbing substance layer and a neutron reflecting substrate. One demonstrated the absence of the mentioned surface waves in terms of the generally accepted model of two media: vacuum contiguous to the plane surface of a substance filled half-space. One pointed out the effect of the excited surface waves of ultracold neutrons on the increase of their anomalous losses in traps [ru

  12. Effects of gypsum and bulk density on neutron probe calibration curves

    International Nuclear Information System (INIS)

    Arslan, Awadis; Razzouk, A.K.

    1993-10-01

    The effects of gypsum and bulk density on the neutron probe calibration curve were studied in the laboratory and in the field. The effect of bulk density was negligible for the soil studied in the laboratory, while it was significant for the field calibration. An increase in the slope of moisture content on a volume basis vs. count ratio with increasing gypsum content at the soil was observed in the laboratory calibration. A simple method for correction of the calibration curve for gypsum content was adopted to obtain a specific curve for each layer. The adapted method requires the gypsum fraction to be estimated for each layer and then incorporated in the calibration curve to improve the coefficient of determination. A field calibration showed an improvement of the determination coefficient by introducing bulk density and gypsum fraction, in addition to count ratio using moisture content on a volume basis as a dependent variable in multi linear regression analysis. The same procedure was successful with variable gravel fractions. (author). 18 refs., 3 figs., 2 tabs

  13. Probing altered hematopoietic progenitors of preleukemic dogs with JANUS fission neutrons

    International Nuclear Information System (INIS)

    Seed, T.M.; Kaspar, L.V.

    1990-01-01

    Toward the goal of developing basic insights to mechanisms of radiation leukemogenesis, the authors have developed a canine model that responds to protracted courses of low-daily-dose gamma irradiation with high incidences of myeloproliferative disease (MPD), principally myeloid leukemia. Using this model system, the authors have identified and partially characterized a four-phase preclinical sequence in the induction of MPD, including (1) suppression, (2) recovery, (3) accommodation, and (4) preleukemic transition. Further, they have identified within this sequence, a critical early hematopoietic target cell event that appears to promote progression of the initial preclinical phase to the second preclinical phase. This key target cell event is characterized by the acquisition of increased radioresistance to low-LET gamma rays by granulocyte/monocyte-committed progenitors (CFU-GM). In order to gain further insight into the basis of this critical event, the acquired survival responses of preleukemic progenitors have been probed in vitro with high-LET fission neutrons. 23 refs., 4 figs., 1 tab

  14. Monovacancy paramagnetism in neutron-irradiated graphite probed by 13C NMR.

    Science.gov (United States)

    Zhang, Zhi Tao; Xu, C; Dmytriieva, Daryna; Molatta, Sebastian; Wosnitza, J; Wang, Y T; Helm, Manfred; Zhou, Shengqiang; Kuehne, Hannes

    2017-09-18

    We report on the magnetic properties of monovacancy defects in neutron-irradiated graphite, probed by $^{13}$C nuclear magnetic resonance spectroscopy. The bulk paramagnetism of the defect moments is revealed by the temperature dependence of the NMR frequency shift and spectral linewidth, both of which follow a Curie behavior, in agreement with measurements of the macroscopic magnetization. Compared to pristine graphite, the fluctuating hyperfine fields generated by the defect moments lead to an enhancement of the $^{13}$C nuclear spin-lattice relaxation rate $1/T_{1}$ by about two orders of magnitude. With an applied magnetic field of 7.1 T, the temperature dependence of $1/T_{1}$ below about 10 K can well be described by a thermally activated form, $1/T_{1}\\propto\\exp(-\\Delta/k_{B}T)$, yielding a singular Zeeman energy of ($0.41\\pm0.01$) meV, in excellent agreement with the sole presence of polarized, non-interacting defect moments. © 2017 IOP Publishing Ltd.

  15. Surface roughness effect on ultracold neutron interaction with a wall and implications for computer simulations

    OpenAIRE

    Steyerl, A.; Malik, S. S.; Desai, A. M.; Kaufman, C.

    2009-01-01

    We review the diffuse scattering and the loss coefficient in ultracold neutron reflection from slightly rough surfaces, report a surprising reduction in loss coefficient due to roughness, and discuss the possibility of transition from quantum treatment to ray optics. The results are used in a computer simulation of neutron storage in a recent neutron lifetime experiment that re-ported a large discrepancy of neutron lifetime with the current particle data value. Our partial re-analysis suggest...

  16. Probing the potential of neutron imaging for biomedical and biological applications

    International Nuclear Information System (INIS)

    Watkin, Kenneth L.; Bilheux, Hassina Z.; Ankner, John Francis

    2009-01-01

    Neutron imaging of biological specimens began soon after the discovery of the neutron by Chadwick in 1932. The first samples included tumors in tissues, internal organs in rats, and bones. These studies mainly employed thermal neutrons and were often compared with X-ray images of the same or equivalent samples. Although neutron scattering is widely used in biological studies, neutron imaging has yet to be exploited to its full capability in this area. This chapter summarizes past and current research efforts to apply neutron radiography to the study of biological specimens, in the expectation that clinical and medical research, as well as forensic science, may benefit from it.

  17. AFM fluid delivery/liquid extraction surface sampling/electrostatic spray cantilever probe

    Science.gov (United States)

    Van Berkel, Gary J.

    2015-06-23

    An electrospray system comprises a liquid extraction surface sampling probe. The probe comprises a probe body having a liquid inlet and a liquid outlet, and having a liquid extraction tip. A solvent delivery conduit is provided for receiving solvent liquid from the liquid inlet and delivering the solvent liquid to the liquid extraction tip. An open liquid extraction channel extends across an exterior surface of the probe body from the liquid extraction tip to the liquid outlet. An electrospray emitter tip is in liquid communication with the liquid outlet of the liquid extraction surface sampling probe. A system for analyzing samples, a liquid junction surface sampling system, and a method of analyzing samples are also disclosed.

  18. Neutron activation probe for measuring the presence of uranium in ore bodies

    International Nuclear Information System (INIS)

    Goldstein, N.P.; Smith, R.C.

    1979-01-01

    A neutron activation proble comprises a pulsed neutron source in series with a plurality of delayed neutron detectors for measuring radioactivity in a well borehole together with a NaI (Tl) counter for measuring the high energy 2.62 MeV gamma line from thorium. The neutron source emits neutrons which produce fission in uranium and thorium in the ore body and the delayed neutron detectors measure the delayed neutrons produced from such fission while the NaI (Tl) counter measures the 2.62 MeV gamma line from the undisturbed thorium in the ore body. The signal from the NaI (Tl) counter is processed and subtracted from the signal from the delayed neutron detectors with the result being indicative of the amount of uranium present in the ore body

  19. Minimum dimensions of rock models for calibration of radiometric probes for the neutron-gamma well logging

    International Nuclear Information System (INIS)

    Czubek, J.A.; Lenda, A.

    1979-01-01

    The minimum dimensions have been calculated assuring 91, 96 and 98 % of the probe response in respect to the infinite medium. The models are of cylindrical form, the probe (source-to-detector distance equal to 60 or 90 cm) being placed on the model axis, symmetrically with respect to the two end-faces. All the models are ''embedded'' in various media, such as: air, sand of 40% porosity and completely saturated with water, sand of 30 % porosity and of moisture content equal to 10 %, and water. The models are of three types of material: sandstone, limestone and dolomite, with various porosities, ranging from 0 to 100 %. The probe response is due to gamma rays arising from the radiativecapture of thermal neutrons. The calculations were carried out for the highest energy line of gamma rays arising in given litology. Gamma-ray flux from the neutron radiative capture has been calculated versus rock porosity and model dimensions and radiation migration lengths determined for given litologies. The minimum dimensions of cylindrical models are given as functions of: porosity, probe length (source-to-detector distance) lithology of model and type of medium surrounding our model. (author)

  20. Neutron and gamma probes: Their use in agronomy. Second edition; Sondas de neutrones y gamma: Sus aplicaciones en agronomia. Segunda edicion

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-02-01

    Water is an essential requirement for life on the planet. It is often the single most limiting factor in crop and livestock production. Water is a scarce resource in many urban and rural environments worldwide. According to the FAO, the global demand for fresh water is doubling every 21 years. The quality of the finite water supplies is also under threat from industrial, agricultural and domestic sources of pollution. The majority of crops are grown under rain-fed conditions and adequate water supply is the main factor limiting crop production in semi-arid and sub-humid regions. On the other hand, currently 20% of the world's arable land is under irrigation providing 35 to 40% of all agricultural production. Irrigation mismanagement poses a serious threat to the environment through groundwater pollution and salinization. It is therefore, essential that water resources be used efficiently by regular monitoring of soil-water status in the unsaturated zone. The neutron depth probe, a nuclear-based technique, is utilized worldwide for this purpose. The neutron moisture gauge, since its introduction some 40 years ago, can now be considered a routine method in soil water studies. Many developments have since been introduced, in particular electronic components, which have significantly improved performance and expanded applications. Although the neutron scattering method is routinely utilised in many developed countries, its use is still limited in developing countries due to several factors. Neutron depth probes contain radioactive sources, which will present health and environmental hazards if a probe is improperly used, stored or disposed of. National and international legislation and regulations must be complied with. The strategic objective of the sub-program Soil and Water Management and Crop Nutrition of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture is to develop and promote the adoption of nuclear-based technologies for optimising soil

  1. Vibrational Surface Electron-Energy-Loss Spectroscopy Probes Confined Surface-Phonon Modes

    Directory of Open Access Journals (Sweden)

    Hugo Lourenço-Martins

    2017-12-01

    Full Text Available Recently, two reports [Krivanek et al. Nature (London 514, 209 (2014NATUAS0028-083610.1038/nature13870, Lagos et al. Nature (London 543, 529 (2017NATUAS0028-083610.1038/nature21699] have demonstrated the amazing possibility to probe vibrational excitations from nanoparticles with a spatial resolution much smaller than the corresponding free-space phonon wavelength using electron-energy-loss spectroscopy (EELS. While Lagos et al. evidenced a strong spatial and spectral modulation of the EELS signal over a nanoparticle, Krivanek et al. did not. Here, we show that discrepancies among different EELS experiments as well as their relation to optical near- and far-field optical experiments [Dai et al. Science 343, 1125 (2014SCIEAS0036-807510.1126/science.1246833] can be understood by introducing the concept of confined bright and dark surface phonon modes, whose density of states is probed by EELS. Such a concise formalism is the vibrational counterpart of the broadly used formalism for localized surface plasmons [Ouyang and Isaacson Philos. Mag. B 60, 481 (1989PMABDJ1364-281210.1080/13642818908205921, García de Abajo and Aizpurua Phys. Rev. B 56, 15873 (1997PRBMDO0163-182910.1103/PhysRevB.56.15873, García de Abajo and Kociak Phys. Rev. Lett. 100, 106804 (2008PRLTAO0031-900710.1103/PhysRevLett.100.106804, Boudarham and Kociak Phys. Rev. B 85, 245447 (2012PRBMDO1098-012110.1103/PhysRevB.85.245447]; it makes it straightforward to predict or interpret phenomena already known for localized surface plasmons such as environment-related energy shifts or the possibility of 3D mapping of the related surface charge densities [Collins et al. ACS Photonics 2, 1628 (2015APCHD52330-402210.1021/acsphotonics.5b00421].

  2. The Fifth International Symposium on Advanced Nuclear Energy Research - neutrons as microscopic probes

    International Nuclear Information System (INIS)

    Hayter, J.B.

    1994-01-01

    New neutron sources being planned, such as the Advanced Neutron Source (ANS) or the European Spallation Source (ESS), will provide an order of magnitude flux increase over what is available today, but neutron scattering will still remain a signal-limited technique. At the same time, the development of new materials, such as polymer and ceramic composites or a variety of complex fluids, will increasingly require neutron-based research. This paper will discuss some of the new techniques which will allow us to make. better use of the available neutrons, either through improved instrumentation or through sample manipulation. Discussion will center primarily on unpolarized neutron techniques since polarized neutrons will be the subject of the next paper

  3. Electronic transport at semiconductor surfaces - from point-contact transistor to micro-four-point probes

    DEFF Research Database (Denmark)

    Hasegawa, S.; Grey, Francois

    2002-01-01

    show that this type of conduction is measurable using new types of experimental probes, such as the multi-tip scanning tunnelling microscope and the micro-four-point probe. The resulting electronic transport properties are intriguing, and suggest that semiconductor surfaces should be considered...

  4. Using the lambda function to evaluate probe measurements of charged dielectric surfaces

    DEFF Research Database (Denmark)

    Rerup, T. O.; Crichton, George C; McAllister, Iain Wilson

    1996-01-01

    The use of Pedersen's λ function to evaluate electrostatic probe measurements of charged dielectric surfaces is demonstrated. With a knowledge of the probe λ function, the procedure by which this function is employed is developed, and thereafter applied to a set of experimental measurements avail...

  5. Nano-confined water in the interlayers of hydrocalumite: Reorientational dynamics probed by neutron spectroscopy and molecular dynamics computer simulations

    Science.gov (United States)

    Kalinichev, A. G.; Faraone, A.; Udovic, T.; Kolesnikov, A. I.; de Souza, N. R.; Reinholdt, M. X.; Kirkpatrick, R.

    2008-12-01

    Layered double hydroxides (LDHs, anionic clays) represent excellent model systems for detailed molecular- level studies of the structure, dynamics, and energetics of nano-confined water in mineral interlayers and nano-pores, because LDH interlayers can have a well-defined structures and contain H2O molecules and a wide variety of anions in structurally well-defined positions and coordinations. [Ca2Al(OH)6]Cl·2H2O, also known as hydrocalumite or Friedel's salt, has a well- ordered Ca,Al distribution in the hydroxide layer and a very high degree of H2O,Cl ordering in the interlayer. It is also one of the only LDH phase for which a single crystal structure refinement is available. Thus, it is currently the best model compound for understanding the structure and dynamical behavior of interlayer and surface species in other, less-ordered, LDHs. We investigated the structural and dynamic behavior of water in the interlayers of hydrocalumite using inelastic (INS) and quasielastic (QENS) neutron scattering and molecular dynamics computer simulations. The comperehensive neutron scattering studies were performed for one fully hydrated and one dehydrated sample of hydrocalumite using several complementary instruments (HFBS, DCS and FANS at NCNR; HRMECS and QENS at IPNS) at temperatures above and below the previously discovered order-disorder interlayer phase transition. Together the experimental and molecular modeling results capture the important details of the dynamics of nano-confined water and the effects of the orientational ordering of H2O molecules above and below the phase transition. They provide otherwise unobtainable experimental information about the transformation of H2O librational and diffusional modes across the order-disorder phase transition and significantly add to our current understanding of the structure and dynamics of water in LDH phases based on the earlier NMR, IR, X-ray, and calorimetric measurements. The approach can now be extended to probe the

  6. Surface erosion of fusion reactor components due to radiation blistering and neutron sputtering

    International Nuclear Information System (INIS)

    Das, S.K.; Kaminsky, M.

    1975-01-01

    Radiation blistering and neutron sputtering can lead to the surface erosion of fusion reactor components exposed to plasma radiations. Recent studies of methods to reduce the surface erosion caused by these processes are discussed

  7. Probing nanoparticle-macromolecule interaction and resultant structure by small-angle neutron scattering

    International Nuclear Information System (INIS)

    Aswal, V.K.

    2013-01-01

    Nanoparticles display unique and distinct characteristics from those of their constituent atoms and bulk materials which are being employed in numerous applications in the fields of medicine, electronics, optics, communications, energy, environment etc. Many of these applications require adjoining of nanoparticles with macromolecules such as proteins, polymers and surfactants to obtain functional objects. For example, nanoparticle-protein complexes are of great importance in controlling enzymatic behavior, targeted drug delivery and developing biocompatible materials. The nanoparticles interfaced with polymers are shown to be useful in developing protein sensor arrays. Interaction of surfactants with nanoparticles is utilized extensively for technical and industrial applications associated with colloidal stability, detergency and design of nanostructured functional interfaces. The interaction of two components, nanoparticles and macromolecule, strongly depends on the characteristics of both the nanoparticles (size, shape, surface roughness, charge density etc.) and macromolecules (type, charge, shape and solution conditions etc.) used. The interaction of macromolecule on nanoparticle surface is a cumulative effect of a number of forces such as electrostatic force, covalent bonding, hydrogen bonding, non-polar interaction, hydrophobic interactions etc. These interactions depending on the system conditions can lead to various structures. Small-angle neutron scattering (SANS) with the possibility to vary contrast is an ideal technique to study such multi-component systems. In this talk, some of our results of SANS from the complexes of nanoparticle-protein and nanoparticle surfactant systems will be discussed. (author)

  8. Surface-sensitive conductivity measurement using a micro multi-point probe approach

    DEFF Research Database (Denmark)

    Perkins, Edward; Barreto, Lucas; Wells, Justin

    2013-01-01

    An instrument for microscale electrical transport measurements in ultra-high vacuum is presented. The setup is constructed around collinear lithographically-created multi-point probes with a contact spacing down to 500 nm. Most commonly, twelve-point probes are used. These probes are approached...... measurements with an equidistant four-point probe for a wide range of contact spacings. In this way, it is possible to distinguish between bulk-like and surface-like conduction. The paper describes the design of the instrument and the approach to data and error analysis. Application examples are given...

  9. Simultaneous surface and depth neural activity recording with graphene transistor-based dual-modality probes.

    Science.gov (United States)

    Du, Mingde; Xu, Xianchen; Yang, Long; Guo, Yichuan; Guan, Shouliang; Shi, Jidong; Wang, Jinfen; Fang, Ying

    2018-05-15

    Subdural surface and penetrating depth probes are widely applied to record neural activities from the cortical surface and intracortical locations of the brain, respectively. Simultaneous surface and depth neural activity recording is essential to understand the linkage between the two modalities. Here, we develop flexible dual-modality neural probes based on graphene transistors. The neural probes exhibit stable electrical performance even under 90° bending because of the excellent mechanical properties of graphene, and thus allow multi-site recording from the subdural surface of rat cortex. In addition, finite element analysis was carried out to investigate the mechanical interactions between probe and cortex tissue during intracortical implantation. Based on the simulation results, a sharp tip angle of π/6 was chosen to facilitate tissue penetration of the neural probes. Accordingly, the graphene transistor-based dual-modality neural probes have been successfully applied for simultaneous surface and depth recording of epileptiform activity of rat brain in vivo. Our results show that graphene transistor-based dual-modality neural probes can serve as a facile and versatile tool to study tempo-spatial patterns of neural activities. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Surface-Enhanced Raman Spectroscopy as a Probe of the Surface Chemistry of Nanostructured Materials.

    Science.gov (United States)

    Dick, Susan; Konrad, Magdalena P; Lee, Wendy W Y; McCabe, Hannah; McCracken, John N; Rahman, Taifur M D; Stewart, Alan; Xu, Yikai; Bell, Steven E J

    2016-07-01

    Surface-enhanced Raman spectroscopy (SERS) is now widely used as a rapid and inexpensive tool for chemical/biochemical analysis. The method can give enormous increases in the intensities of the Raman signals of low-concentration molecular targets if they are adsorbed on suitable enhancing substrates, which are typically composed of nanostructured Ag or Au. However, the features of SERS that allow it to be used as a chemical sensor also mean that it can be used as a powerful probe of the surface chemistry of any nanostructured material that can provide SERS enhancement. This is important because it is the surface chemistry that controls how these materials interact with their local environment and, in real applications, this interaction can be more important than more commonly measured properties such as morphology or plasmonic absorption. Here, the opportunity that this approach to SERS provides is illustrated with examples where the surface chemistry is both characterized and controlled in order to create functional nanomaterials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Reversible electrochemical modification of the surface of a semiconductor by an atomic-force microscope probe

    Energy Technology Data Exchange (ETDEWEB)

    Kozhukhov, A. S., E-mail: antonkozhukhov@yandex.ru; Sheglov, D. V.; Latyshev, A. V. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2017-04-15

    A technique for reversible surface modification with an atomic-force-microscope (AFM) probe is suggested. In this method, no significant mechanical or topographic changes occur upon a local variation in the surface potential of a sample under the AFM probe. The method allows a controlled relative change in the ohmic resistance of a channel in a Hall bridge within the range 20–25%.

  12. Eddy current array probe for detection of surface breaking cracks in the extrados of feeder bends

    International Nuclear Information System (INIS)

    Obrutsky, L.S.; Cassidy, R.A.; Chaplin, K.; Martin, P.; Bureau, J.F.

    2006-01-01

    A new eddy current array probe has been implemented as a straightforward and promising technique for detection of outer diameter (OD) surface-breaking cracks on the extrados of feeder bends. The design is based on previous work performed at AECL, which had demonstrated that eddy current probes with laterally displaced transmit-receive coils can overcome some of the limitations of inspecting ferritic steel components for surface-breaking cracks. The Feeder Integrity Joint Program-CANDU Owners Group Inc. (FIJP-COG) Non-Destructive Evaluation (NDE) Team members commissioned AECL to work in collaboration with the probe manufacturer ZETEC, to develop a field usable eddy current array probe. The objective was to acquire a technique with the following capabilities: fast scanning non-contact inspection technique for surface breaking discontinuities; full inspection of the bend extrados OD surface in a single scan; ability to inspect first and second bends with similar settings and capabilities; permanent record for future reference; axial and circumferential crack detection in a single scan; capability to detect OD surface-breaking cracks, which can provide additional information to that provided by ultrasonic testing (UT) for flaw characterization, and detection threshold: Surface breaking cracks equivalent to a 0.5 mm deep, 10 mm long EDM notch located on the OD of the bend extrados. This paper discusses the basis for probe design, summarizes the experimental work to evaluate probe capabilities and analyzes the results from the field trial. (author)

  13. Eddy current array probe for detection of surface breaking cracks in the extrados of feeder bends

    Energy Technology Data Exchange (ETDEWEB)

    Obrutsky, L.S.; Cassidy, R.A.; Chaplin, K. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)]. E-mail: obrutskyl@aecl.ca; Martin, P. [NB Power, Point Lepreau NGS, Point Lepreau, New Brunswick (Canada)]. E-mail: PMartin@nbpower.com; Bureau, J.F. [Zetec, Quebec, Quebec (Canada)]. E-mail: jean-francois.bureau@zetec.com

    2006-07-01

    A new eddy current array probe has been implemented as a straightforward and promising technique for detection of outer diameter (OD) surface-breaking cracks on the extrados of feeder bends. The design is based on previous work performed at AECL, which had demonstrated that eddy current probes with laterally displaced transmit-receive coils can overcome some of the limitations of inspecting ferritic steel components for surface-breaking cracks. The Feeder Integrity Joint Program-CANDU Owners Group Inc. (FIJP-COG) Non-Destructive Evaluation (NDE) Team members commissioned AECL to work in collaboration with the probe manufacturer ZETEC, to develop a field usable eddy current array probe. The objective was to acquire a technique with the following capabilities: fast scanning non-contact inspection technique for surface breaking discontinuities; full inspection of the bend extrados OD surface in a single scan; ability to inspect first and second bends with similar settings and capabilities; permanent record for future reference; axial and circumferential crack detection in a single scan; capability to detect OD surface-breaking cracks, which can provide additional information to that provided by ultrasonic testing (UT) for flaw characterization, and detection threshold: Surface breaking cracks equivalent to a 0.5 mm deep, 10 mm long EDM notch located on the OD of the bend extrados. This paper discusses the basis for probe design, summarizes the experimental work to evaluate probe capabilities and analyzes the results from the field trial. (author)

  14. Conformation of bovine submaxillary mucin layers on hydrophobic surface as studied by biomolecular probes

    DEFF Research Database (Denmark)

    Pakkanen, Kirsi I.; Madsen, Jan Busk; Lee, Seunghwan

    2015-01-01

    In the present study, the conformational changes of bovine submaxillary mucin (BSM) adsorbed on a hydrophobic surface (polystyrene (PS)) as a function of concentration in bulk solution (up to 2mg/mL) have been investigated with biomolecular probe-based approaches, including bicinchoninic acid (BCA),enzyme-linkedimmunosorbentassay(EIA...... solution. Adsorbed masses of BSM onto hydrophobic surface, as probe by BCA, showed a continuously increasing trend up to 2mg/mL. But, the signals from EIA and ELLA, which probe the concentration of available unglycosylatedC-terminals and the central glycosylated regions, respectively, showed complicated...

  15. Water utilization of vegetables grown under plastic greenhouse conditions in Ankara using neutron probe technique

    International Nuclear Information System (INIS)

    Halitligil, M.B.; Kislal, H.; Sirin, H.; Sirin, C.; Kilicaslan, A.

    2004-01-01

    In order to find suitable varieties of tomato, pepper and cucumber for plastic greenhouse conditions in Ankara and ensure both higher yields and lower NO 3 leaching greenhouse experiments were conducted for three years. In the first year (2001) of the experiment four different varieties from each vegetable, namely, Tomato (Ecem F 1 , 9920 F 1 , 2116 F 1 and Yazg1 F 1 ), Cucumber (Hizir F 1 , Rapido, Hana, and Luna) and Pepper (1245 F 1 , 730 F 1 , Serademre 8 and 710 F 1 ) had been grown in the plastic greenhouse using drip irrigation-fertilization system. Yazg1 F 1 variety for tomato, Hizir F 1 variety for cucumber and Serademre 8 variety for pepper were chosen to be suitable varieties to grow in the plastic greenhouse conditions in Ankara. One access tube in each N 3 and N 0 treatment plots of tomato, cucumber and pepper in 2002 and 2003 experiments were installed for the soil moisture determinations at 30, 60 and 90 cm depths. Readings with the neutron probe were taken before planting and after harvest for the water consumption calculations using the water balance approach and the WUE was calculated on the basis of the ratio of dry matter weight to the amount of water consumed. Tensiometer and suction cups were installed at 15, 30, 45 and 60 cm depths only to N 1 , N 2 and N 3 treatments plots of each vegetable in 2002 and 2003. Tensiometer readings were taken just before irrigation. Also, soil solution samples from suction cups were taken at final harvest and NO 3 determinations were done with RQFLEX nitrate test strips. Significantly higher yields and WUE values were obtained when the same amount of N fertilizer is applied through fertigation compared to the treatment where N fertilizer applied to the soil then drip irrigated. The nitrate concentrations of the soil solution increased as the N rates increased and no NO 3 had been found in the soil solution taken from 75 cm soil depth, indicating that no leaching of N fertilizer occurred beyond 75 cm soil depth

  16. Water utilization of vegetables grown under plastic greenhouse conditions in Ankara using neutron probe technique

    International Nuclear Information System (INIS)

    Halitligil, M.B.; Kislal, H.; Sirin, H.; Sirin, C.; Kilicaslan, A.

    2004-01-01

    Full text: In order to find suitable varieties of tomato, pepper and cucumber for plastic greenhouse conditions in Ankara and ensure both higher yields and lower NO 3 leaching greenhouse experiments were conducted for three years. In the first year (2001) of the experiment four different varieties from each vegetable, namely, Tomato (Ecem F 1 , 9920 F 1 , 2116 F 1 and Yazg1 F 1 ), Cucumber (Hizir F 1 , Rapido, Hana, and Luna) and Pepper (1245 F 1 , 730 F 1 , Serademre 8 and 710 F 1 ) had been grown in the plastic greenhouse using drip irrigation-fertiligation system. Yazg1 F 1 variety for tomato, Hizir F 1 variety for cucumber and Serademre 8 variety for pepper were chosen to be suitable varieties to grow in the plastic greenhouse conditions in Ankara. One access tube in each N 3 and N 0 treatment plots of tomato, cucumber and pepper in 2002 and 2003 experiments were installed for the soil moisture determinations at 30, 60 and 90 cm depths. Readings with the neutron probe were taken before planting and after harvest for the water consumption calculations using the water balance approach and the WUE was calculated on the basis of the ratio of dry matter weight to the amount of water consumed. Tensiometer and suction cups were installed at 15, 30, 45 and 60 cm depths only to N 1 , N 2 and N 3 treatments plots of each vegetable in 2002 and 2003. Tensiometer readings were taken just before irrigation. Also, soil solution samples from suction cups were taken at final harvest and NO 3 determinations were done with RQFLEX nitrate test strips. Significantly higher yields and WUE values were obtained when the same amount of N fertilizer is applied through fertigation compared to the treatment where N fertilizer applied to the soil then drip irrigated. The nitrate concentrations of the soil solution increased as the N rates increased and no NO 3 had been found in the soil solution taken from 75 cm soil depth, indicating that no leaching of N fertilizer occurred beyond 75 cm

  17. Aerial Neutron Detection of Cosmic-Ray Interactions with the Earth's Surface

    International Nuclear Information System (INIS)

    Richard Maurer

    2008-01-01

    We have demonstrated the ability to measure the neutron flux produced by the cosmic-ray interaction with nuclei in the ground surface using aerial neutron detection. High energy cosmic-rays (primarily muons with GeV energies) interact with the nuclei in the ground surface and produce energetic neutrons via spallation. At the air-surface interface, the neutrons produced by spallation will either scatter within the surface material, become thermalized and reabsorbed, or be emitted into the air. The mean free path of energetic neutrons in air can be hundreds of feet as opposed to a few feet in dense materials. As such, the flux of neutrons escaping into the air provides a measure of the surface nuclei composition. It has been demonstrated that this effect can be measured at long range using neutron detectors on low flying helicopters. Radiological survey measurements conducted at Government Wash in Las Vegas, Nevada, have shown that the neutron background from the cosmic-soil interactions is repeatable and directly correlated to the geological data. Government Wash has a very unique geology, spanning a wide variety of nuclide mixtures and formations. The results of the preliminary measurements are presented

  18. Using Cosmic-Ray Neutron Probes to Monitor Landscape Scale Soil Water Content in Mixed Land Use Agricultural Systems

    International Nuclear Information System (INIS)

    Franz, Trenton E.; Wahbi, Ammar; Weltin, Georg; Heng, Lee; Dercon, Gerd; Vreugdenhi, Mariette; Oismueller, Markus; Strauss, Peter; Desilets, Darin

    2016-01-01

    With an ever-increasing demand for natural resources and the societal need to understand and predict natural disasters such as flood, soil water content (SWC) observations remain a critical variable to monitor in order to optimally allocate resources, establish early warning systems, and improve weather forecasts. However, routine agricultural production practices of soil cultivation, planting, and harvest make the operation and maintenance of direct contact point sensors for long-term monitoring a challenging task. In this work, we used Cosmic-Ray Neutron Probe (CRNP) to monitor landscape average SWC in a mixed agricultural land use system in northeast Austria since December 2013.

  19. Investigation of inelastic scattering of ultracold neutrons with small energy transfer at solid state surfaces

    International Nuclear Information System (INIS)

    Lychagin, E.V.; Muzychka, A.Yu.; Nekhaev, G.V.; Strelkov, A.V.; Shvetsov, V.N.; Nesvizhevskij, V.V.; Tal'daev, R.R.

    2001-01-01

    Inelastic scattering of neutrons with small energy transfer of ∼10 -7 eV was investigated using gravitational UCN spectrometer. The probability of such a process at stainless steel and beryllium surfaces was measured. It was also estimated at copper surface. The measurement showed that the detected flux of neutrons scattered at beryllium and copper surfaces is ∼ 2 times higher at room temperature compared to that at the liquid nitrogen temperature. (author)

  20. Surface-enhanced Raman scattering based nonfluorescent probe for multiplex DNA detection.

    Science.gov (United States)

    Sun, Lan; Yu, Chenxu; Irudayaraj, Joseph

    2007-06-01

    To provide rapid and accurate detection of DNA markers in a straightforward, inexpensive, and multiplex format, an alternative surface-enhanced Raman scattering based probe was designed and fabricated to covalently attach both DNA probing sequence and nonfluorescent Raman tags to the surface of gold nanoparticles (DNA-AuP-RTag). The intensity of Raman signal of the probes could be controlled through the surface coverage of the nonfluorescent Raman tags (RTags). Detection sensitivity of these probes could be optimized by fine-tuning the amount of DNA molecules and RTags on the probes. Long-term stability of the DNA-AuP-RTag probes was found to be good (over 3 months). Excellent multiplexing capability of the DNA-AuP-RTag scheme was demonstrated by simultaneous identification of up to eight probes in a mixture. Detection of hybridization of single-stranded DNA to its complementary targets was successfully accomplished with a long-term goal to use nonfluorescent RTags in a Raman-based DNA microarray platform.

  1. Critical reflection activation analysis - a new near-surface probe

    International Nuclear Information System (INIS)

    Gunn, J.M.F.; Trohidou, K.N.

    1988-09-01

    We propose a new surface analytic technique, Critical Reflection Activation Analysis (CRAA). This technique allows accurate depth profiling of impurities ≤ 100A beneath a surface. The depth profile of the impurity is simply related to the induced activity as a function of the angle of reflection. We argue that the technique is practical and estimate its accuracy. (author)

  2. Friction behavior of nano-textured polyimide surfaces measured by AFM colloidal probe

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoliang [College of Equipment Manufacturing, Hebei University of Engineering, Handan 056038 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wu, Chunxia; Che, Hongwei; Hou, Junxian [College of Equipment Manufacturing, Hebei University of Engineering, Handan 056038 (China); Jia, Junhong, E-mail: jhjia@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2014-11-30

    Highlights: • Flat PI film and nano-textured PI film were prepared by spin-coating process. • The nano-textured PI surface has effectively reduced the adhesion and friction. • Friction increased with the increasing of contact area and adhesion. • The growth rate of friction decreased with the increasing of applied load. - Abstract: Flat polyimide (PI) film and silicon dioxide nanoparticle-textured PI film were prepared by means of the spin-coating technique. The adhesion and friction properties of the flat PI surface and nano-textured PI surface were investigated by a series of Atomic force microscope (AFM) colloidal probes. Experimental results revealed that the nano-textured PI surface can significantly reduce the adhesive force and friction force, compared with the flat PI surface. The main reason is that the nano-textures can reduce the contact area between the sample surface and colloidal probe. The effect of colloidal probe size on the friction behavior of the flat and nano-textured PI surfaces was evaluated. The adhesive force and friction force of nano-textured PI surface were increased with the increasing of the size of interacting pairs (AFM colloidal probe) due to the increased contact area. Moreover, the friction forces of flat and nano-textured PI surfaces were increased with applied load and sliding velocity.

  3. Advances in associated-particle sealed-tube neutron probe diagnostics for substance detection

    International Nuclear Information System (INIS)

    Rhodes, E.; Dickerman, C.E.; Frey, M.

    1995-01-01

    The development and investigation of a small associated-particle sealed-tube neutron generator (APSTNG) shows potential to allow the associated-particle diagnostic method to be moved out of the laboratory into field applications. The APSTNG interrogates the inspected object with 14-MeV neutrons generated from the deuterium-tritium reaction and detects the alpha-particle associated with each neutron inside a cone encompassing the region of interest. Gamma-ray spectra of resulting neutron reactions identify many nuclides. Flight-times determined from detection times of the gamma-rays and alpha-particles can yield a separate coarse tomographic image of each identified nuclide, from a single orientation. Chemical substances are identified by comparing relative spectral line intensities with ratios of elements in reference compounds. The high-energy neutrons and gamma-rays penetrate large objects and dense materials. Generally no collimators or radiation shielding are needed. Proof-of-concept laboratory experiments have been successfully performed for simulated nuclear, chemical warfare, and conventional munitions. Most recently, inspection applications have been investigated for radioactive waste characterization, presence of cocaine in propane tanks, and uranium and plutonium smuggling. Based on lessons learned with the present APSTNG system, an advanced APSTNG tube (along with improved high voltage supply and control units) is being designed and fabricated that will be transportable and rugged, yield a substantial neutron output increase, and provide sufficiently improved lifetime to allow operation at more than an order of magnitude increase in neutron flux

  4. Probing inhibitory effects of nanocrystalline cellulose: inhibition versus surface charge

    Science.gov (United States)

    Male, Keith B.; Leung, Alfred C. W.; Montes, Johnny; Kamen, Amine; Luong, John H. T.

    2012-02-01

    NCC derived from different biomass sources was probed for its plausible cytotoxicity by electric cell-substrate impedance sensing (ECIS). Two different cell lines, Spodoptera frugiperda Sf9 insect cells and Chinese hamster lung fibroblast V79, were exposed to NCC and their spreading and viability were monitored and quantified by ECIS. Based on the 50%-inhibition concentration (ECIS50), none of the NCC produced was judged to have any significant cytotoxicity on these two cell lines. However, NCC derived from flax exhibited the most pronounced inhibition on Sf9 compared to hemp and cellulose powder. NCCs from flax and hemp pre-treated with pectate lyase were also less inhibitory than NCCs prepared from untreated flax and hemp. Results also suggested a correlation between the inhibitory effect and the carboxylic acid contents on the NCC.

  5. Surface roughness effect on ultracold neutron interaction with a wall and implications for computer simulations

    International Nuclear Information System (INIS)

    Steyerl, A.; Malik, S. S.; Desai, A. M.; Kaufman, C.

    2010-01-01

    We review the diffuse scattering and the loss coefficient in ultracold neutron reflection from slightly rough surfaces, report a surprising reduction in loss coefficient due to roughness, and discuss the possibility of transition from quantum treatment to ray optics. The results are used in a computer simulation of neutron storage in a recent neutron lifetime experiment that reported a large discrepancy of neutron lifetime with the current particle data value. Our partial reanalysis suggests the possibility of systematic effects that were not included in this publication.

  6. Probing the nuclear equation of state by heavy-ion reactions and neutron star properties

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, P K; Cassing, W; Thoma, M H [Inst. fuer Theoretische Physik, Univ. Giessen (Germany)

    1998-06-01

    We discuss the nuclear equation of state (EOS) using a non-linear relativistic transport model. From the baryon flow for Ni + Ni as well as Au + Au systems we find that the strength of the vector potential has to be reduced at high density or at high relative momenta to describe the experimental flow data at 1-2 A GeV. We use the same dynamical model to calculate the nuclear EOS and then employ this EOS to neutron star structure calculations. We consider the core of the neutron star to be composed of neutrons with an admixture of protons, electrons, muons, sigmas and lambdas at zero temperature. We find that the nuclear equation of state is softer at high densities and hence the maximum mass and the radius of the neutron star are in the observable range of M {proportional_to} 1.7 M{sub s}un and R = 8 km, respectively. (orig.)

  7. Oscillations During Thermonuclear X-ray Bursts: A New Probe of Neutron Stars

    Science.gov (United States)

    Strohmayer, Tod E.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    Observations of thermonuclear (also called Type 1) X-ray bursts from neutron stars in low mass X-ray binaries (LMXB) with the Rossi X-ray Timing Explorer (RXTE) have revealed large amplitude, high coherence X-ray brightness oscillations with frequencies in the 300 - 600 Hz range. Substantial spectral and timing evidence point to rotational modulation of the X-ray burst flux as the cause of these oscillations, and it is likely that they reveal the spin frequencies of neutron stars in LMXB from which they are detected. Here we review the status of our knowledge of these oscillations and describe how they can be used to constrain the masses and radii of neutron stars as well as the physics of thermonuclear burning on accreting neutron stars.

  8. Neutronic density perturbation by probes; Pertubacion de densidades neutronicas por sondas

    Energy Technology Data Exchange (ETDEWEB)

    Vigon, M A; Diez, L

    1956-07-01

    The introduction of absorbent materials of neutrons in diffuser media, produces local disturbances of neutronic density. The disturbance depends especially on the nature and size of the absorbent. Approximated equations which relates te disturbance and the distance to the absorbent in the case of thin disks have been drawn. The experimental comprobation has been carried out in two especial cases. In both cases the experimental results are in agreement with the calculated values from these equations. (Author)

  9. Atom Probe Tomography Characterization of the Solute Distributions in a Neutron-Irradiated and Annealed Pressure Vessel Steel Weld

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M.K.

    2001-01-30

    A combined atom probe tomography and atom probe field ion microscopy study has been performed on a submerged arc weld irradiated to high fluence in the Heavy-Section Steel irradiation (HSSI) fifth irradiation series (Weld 73W). The composition of this weld is Fe - 0.27 at. % Cu, 1.58% Mn, 0.57% Ni, 0.34% MO, 0.27% Cr, 0.58% Si, 0.003% V, 0.45% C, 0.009% P, and 0.009% S. The material was examined after five conditions: after a typical stress relief treatment of 40 h at 607 C, after neutron irradiation to a fluence of 2 x 10{sup 23} n m{sup {minus}2} (E > 1 MeV), and after irradiation and isothermal anneals of 0.5, 1, and 168 h at 454 C. This report describes the matrix composition and the size, composition, and number density of the ultrafine copper-enriched precipitates that formed under neutron irradiation and the change in these parameters with post-irradiation annealing treatments.

  10. Surface forces studied with colloidal probe atomic force microscopy

    NARCIS (Netherlands)

    Giesbers, M.

    2001-01-01

    Forces between surfaces are a determining factor for the performance of natural as well as synthetic colloidal systems, and play a crucial role in industrial production processes. Measuring these forces is a scientific and experimental challenge and over the years several techniques have

  11. Applying the universal neutron transport codes to the calculation of well-logging probe response at different rock porosities

    International Nuclear Information System (INIS)

    Bogacz, J.; Loskiewicz, J.; Zazula, J.M.

    1991-01-01

    The use of universal neutron transport codes in order to calculate the parameters of well-logging probes presents a new approach first tried in U.S.A. and UK in the eighties. This paper deals with first such an attempt in Poland. The work is based on the use of MORSE code developed in Oak Ridge National Laboratory in U.S.A.. Using CG MORSE code we calculated neutron detector response when surrounded with sandstone of porosities 19% and 38%. During the work it come out that it was necessary to investigate different methods of estimation of the neutron flux. The stochastic estimation method as used currently in the original MORSE code (next collision approximation) can not be used because of slow convergence of its variance. Using the analog type of estimation (calculation of the sum of track lengths inside detector) we obtained results of acceptable variance (∼ 20%) for source-detector spacing smaller than 40 cm. The influence of porosity on detector response is correctly described for detector positioned at 27 cm from the source. At the moment the variances are quite large. (author). 33 refs, 8 figs, 8 tabs

  12. Hydrogen dynamics in the low temperature phase of LiBH{sub 4} probed by quasielastic neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Remhof, Arndt, E-mail: arndt.remhof@empa.ch [Empa, Swiss Federal Institute for Materials Science and Technology, Hydrogen and Energy, CH-8600 Dübendorf (Switzerland); Züttel, Andreas [Empa, Swiss Federal Institute for Materials Science and Technology, Hydrogen and Energy, CH-8600 Dübendorf (Switzerland); Ramirez-Cuesta, Timmy; García-Sakai, Victoria [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Frick, Bernhard [Institut Laue-Langevin, F-38002 Grenoble (France)

    2013-12-12

    Highlights: • Inelastic fixed window sans offer new possibilities in neutron backscattering spectrometers. • Two different kind of reorientational motion were identified in the low temperature phase of LiBH{sub 4}. • Thermally activated jump rotation. - Abstract: LiBH{sub 4} contains 18.5 wt% hydrogen and undergoes a structural phase transition (orthorhombic → hexagonal) at 381 K which is associated with a large increase in hydrogen and lithium solid-state mobility. We investigated the hydrogen dynamics in the low temperature phase of LiBH{sub 4} by quasielastic neutron scattering, including a new kind of inelastic fixed window scan (IFWS). In the temperature range from 175 to 380 K the H-dynamics is dominated by thermally activated rotational jumps of the [BH{sub 4}]{sup −} anion around the c3 axis with an activation energy of about 162 meV. In agreement with earlier NMR data, a second type of thermally activated motion with an activation energy of about 232 meV could be identified using the IFWS. The present study of hydrogen dynamics in LiBH{sub 4} illustrates the feasibility of using IFWS on neutron backscattering spectrometers as a probe of localised motion.

  13. Scanning-probe-microscopy of polyethylene terephthalate surface treatment by argon ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Espinoza-Beltran, Francisco [Polymer & Biopolymer Group, Libramiento Norponiente no. 2000, Cinvestav Queretaro, Queretaro 76230 (Mexico); Sanchez, Isaac C. [Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); España-Sánchez, Beatriz L.; Mota-Morales, Josué D.; Carrillo, Salvador; Enríquez-Flores, C.I. [Polymer & Biopolymer Group, Libramiento Norponiente no. 2000, Cinvestav Queretaro, Queretaro 76230 (Mexico); Poncin-Epaillard, Fabienne, E-mail: epaill@univ-lemans.fr [Institute for Molecules and Materials, UMR CNRS 6283, Av. O. Messiaen, Universitè du Maine, Le Mans 72085 (France); Luna-Barcenas, Gabriel, E-mail: gluna@qro.cinvestav.mx [Polymer & Biopolymer Group, Libramiento Norponiente no. 2000, Cinvestav Queretaro, Queretaro 76230 (Mexico)

    2015-11-01

    Highlights: • Kelvin-probe-force microscopy helps study of PET surface treated by Ar ion beam. • Ar ion beam surface treatment promotes chain scission and N insertion. • Surface roughness and work function increases as intensity of ion energy increases. • Adhesive force of PET decrease due to the surface changes by ion bombardment. - Abstract: The effect of argon (Ar{sup +}) ion beam treatment on the surface of polyethylene terephthalate (PET) samples was studied by scanning probe microscopy (SPM) and the changes in surface topography were assessed by atomic force microscopy (AFM). Kelvin probe force microscopy (KPFM) sheds light of adhesion force between treated polymer films and a Pt/Cr probe under dry conditions, obtaining the contact potential difference of material. As a result of Ar{sup +} ion bombardment, important surface chemical changes were detected by X-ray photoelectron spectroscopy (XPS) measurements such as chains scission and incorporation of nitrogen species. Ion beam treatment increases the surface roughness from 0.49 ± 0.1 nm to 7.2 ± 0.1 nm and modify the surface potential of PET samples, decreasing the adhesive forces from 12.041 ± 2.1 nN to 5.782 ± 0.06 nN, and producing a slight increase in the electronic work function (Φ{sub e}) from 5.1 V (untreated) to 5.2 V (treated). Ar{sup +} ion beam treatment allows to potentially changing the surface properties of PET, modifying surface adhesion, improving surface chemical changes, wetting properties and surface potential of polymers.

  14. Photoassisted Kelvin probe force microscopy at GaN surfaces: The role of polarity

    Science.gov (United States)

    Wei, J. D.; Li, S. F.; Atamuratov, A.; Wehmann, H.-H.; Waag, A.

    2010-10-01

    The behavior of GaN surfaces during photoassisted Kelvin probe force microscopy is demonstrated to be strongly dependant on surface polarity. The surface photovoltage of GaN surfaces illuminated with above-band gap light is analyzed as a function of time and light intensity. Distinct differences between Ga-polar and N-polar surfaces could be identified, attributed to photoinduced chemisorption of oxygen during illumination. These differences can be used for a contactless, nondestructive, and easy-performable analysis of the polarity of GaN surfaces.

  15. Associated-particle sealed-tube neutron probe: Detection of explosives, contraband, and nuclear materials

    International Nuclear Information System (INIS)

    Rhodes, E.; Dickerman, C.E.

    1996-01-01

    Continued research and development of the APSTNG shows the potential for practical field use of this technology for detection of explosives, contraband, and nuclear materials. The APSTNG (associated-particle sealed-tube generator) inspects the item to be examined using penetrating 14-MeV neutrons generated by the deuterium-tritium reaction inside a compact accelerator tube. An alpha detector built into the sealed tube detects the alpha-particle associated with each neutron emitted in a cone encompassing the volume to be inspected. Penetrating high-energy gamma-rays from the resulting neutron reactions identify specific nuclides inside the volume. Flight-times determined from the detection times of gamma-rays and alpha-particles separate the prompt and delayed gamma-ray spectra and allow a coarse 3-D image to be obtained of nuclides identified in the prompt spectrum. The generator and detectors can be on the same side of the inspected object, on opposite sides, or with intermediate orientations. Thus, spaces behind walls and other confined regions can be inspected. Signals from container walls can be discriminated against using the flight-time technique. No collimators or shielding are required, the neutron generator is relatively small, and commercial-grade electronics are employed. The use of 14-MeV neutrons yields a much higher cross-section for detecting nitrogen than that for systems based on thermal-neutron reactions alone, and the broad range of elements with significant 14-MeV neutron cross-sections extends explosives detection to other elements including low-nitrogen compounds, and allows detection of many other substances. Proof-of-concept experiments have been successfully performed for conventional explosives, chemical warfare agents, cocaine, and fissionable materials

  16. Micro reflectance difference techniques: Optical probes for surface exploration

    Energy Technology Data Exchange (ETDEWEB)

    Lastras-Martinez, L.F.; Del Pozo-Zamudio, O.; Herrera-Jasso, R.; Ulloa-Castillo, N.A.; Balderas-Navarro, R.E.; Ortega-Gallegos, J.; Lastras-Martinez, A. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi, S.L.P. (Mexico)

    2012-06-15

    Micro reflectance difference spectroscopy ({mu}-RDS) is a promising tool for the in-situ and ex-situ characterization of semiconductors surfaces and interfaces. We discuss and compare two different approaches used to measure {mu}-RD spectra. One is based on a charge-coupled device (CCD) camera, while the other uses a laser and a XY translation stage. To show the performance of these systems, we have measured surface optical anisotropies of GaSb(001) sample on which anisotropic strains have been generated by preferential mechanical polishing along [110] and [1 anti 10] directions. The spectrometers are complementary and the selection of one of them depends on the sample to be investigated and on experimental conditions. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Few-Nucleon Research at TUNL: Probing Two- and Three-Nucleon Interactions with Neutrons

    Science.gov (United States)

    Howell, C. R.; Tornow, W.; Witała, H.

    2016-03-01

    The central goal of few-nucleon research at the Triangle Universities Nuclear Laboratory (TUNL) is to perform measurements that contribute to advancing ab-initio calculations of nuclear structure and reactions. The program aims include evaluating theoretical treatments of few-nucleon reaction dynamics through strategically comparing theory predictions to data, determining properties of the neutron-neutron interaction that are not accessible in two-nucleon reactions, and searching for evidence of longrange features of three-nucleon interactions, e.g., spin and isospin dependence. This paper will review studies of three- and four-nucleon systems at TUNL conducted using unpolarized and polarized neutron beams. Measurements of neutron-induced reactions performed by groups at TUNL over the last six years are described in comparison with theory predictions. The results are discussed in the context of the program goals stated above. Measurements of vector analyzing powers for elastic scattering in A=3 and A=4 systems, differential cross sections for neutron-deuteron elastic scattering and neutrondeuteron breakup in several final-state configurations are described. The findings from these studies and plans for the coming three years are presented in the context of worldwide activities in this front, in particular, research presented in this session.

  18. Few-Nucleon Research at TUNL: Probing Two- and Three-Nucleon Interactions with Neutrons

    Directory of Open Access Journals (Sweden)

    Howell C.R.

    2016-01-01

    Full Text Available The central goal of few-nucleon research at the Triangle Universities Nuclear Laboratory (TUNL is to perform measurements that contribute to advancing ab-initio calculations of nuclear structure and reactions. The program aims include evaluating theoretical treatments of few-nucleon reaction dynamics through strategically comparing theory predictions to data, determining properties of the neutron-neutron interaction that are not accessible in two-nucleon reactions, and searching for evidence of longrange features of three-nucleon interactions, e.g., spin and isospin dependence. This paper will review studies of three- and four-nucleon systems at TUNL conducted using unpolarized and polarized neutron beams. Measurements of neutron-induced reactions performed by groups at TUNL over the last six years are described in comparison with theory predictions. The results are discussed in the context of the program goals stated above. Measurements of vector analyzing powers for elastic scattering in A=3 and A=4 systems, differential cross sections for neutron-deuteron elastic scattering and neutrondeuteron breakup in several final-state configurations are described. The findings from these studies and plans for the coming three years are presented in the context of worldwide activities in this front, in particular, research presented in this session.

  19. Ultrasound surface probe as a screening method for evaluating the patients with blunt abdominal trauma

    Directory of Open Access Journals (Sweden)

    Mohammad Nasr-Esfahani

    2014-01-01

    Full Text Available Background: Blunt abdominal trauma is one of the causes of mortality in emergency department. Free fluid in the abdomen due to intra-abdominal blunt trauma can be determined by the surface probe of ultrasound. Since the importance of this free fluid in hemodynamic stable patients with blunt trauma is associated with the unknown outcome for surgeons, this study was performed to evaluate the role of ultrasound surface probe as a screening method in evaluating the patients with blunt abdominal trauma. Materials and Methods: A descriptive-analytical study was done on 45 patients with blunt abdominal trauma and hemodynamic stability. The patients were evaluated twice during the three-hours, including repeated ultrasound surface probe and clinical examinations. Computerized tomography was also performed. The patients were divided based on the amount of the free fluid in the abdomen during the evaluations into two groups: Fixed or increased, and decreased free fluid. The results of the different evaluated methods were compared using the sensitivity and specificity. Results: From 17 patients with CT abnormalities, free fluid increased in 14 patients (82.4%. Free fluid was decreased in three patients who were discharged well from the surgery service without any complication. Surface probe in prognosis detection had a sensitivity of 82.4% and specificity of 92.9%. The percentage of false positive and negative ultrasound compared with CT scan was 7.1% and 17.6%. Also, positive and negative predictive value of the ultrasound with surface probe was 87.5% and 89.7% respectively. Conclusion: The use of the ultrasound with surface probe in the diagnosis of free fluid in blunt abdominal trauma in hemodynamic stable patients can be considered as a useful screening method.

  20. Tribological behavior of micro/nano-patterned surfaces in contact with AFM colloidal probe

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xiaoliang; Wang Xiu; Kong Wen [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Yi Gewen [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Jia Junhong, E-mail: jhjia@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2011-10-15

    In effort to investigate the influence of the micro/nano-patterning or surface texturing on the nanotribological properties of patterned surfaces, the patterned polydimethylsiloxane (PDMS) surfaces with pillars were fabricated by replica molding technique. The surface morphologies of patterned PDMS surfaces with varying pillar sizes and spacing between pillars were characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). The AFM/FFM was used to acquire the friction force images of micro/nano-patterned surfaces using a colloidal probe. A difference in friction force produced a contrast on the friction force images when the colloidal probe slid over different regions of the patterned polymer surfaces. The average friction force of patterned surface was related to the spacing between the pillars and their size. It decreased with the decreasing of spacing between the pillars and the increasing of pillar size. A reduction in friction force was attributed to the reduced area of contact between patterned surface and colloidal probe. Additionally, the average friction force increased with increasing applied load and sliding velocity.

  1. Tribological behavior of micro/nano-patterned surfaces in contact with AFM colloidal probe

    International Nuclear Information System (INIS)

    Zhang Xiaoliang; Wang Xiu; Kong Wen; Yi Gewen; Jia Junhong

    2011-01-01

    In effort to investigate the influence of the micro/nano-patterning or surface texturing on the nanotribological properties of patterned surfaces, the patterned polydimethylsiloxane (PDMS) surfaces with pillars were fabricated by replica molding technique. The surface morphologies of patterned PDMS surfaces with varying pillar sizes and spacing between pillars were characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). The AFM/FFM was used to acquire the friction force images of micro/nano-patterned surfaces using a colloidal probe. A difference in friction force produced a contrast on the friction force images when the colloidal probe slid over different regions of the patterned polymer surfaces. The average friction force of patterned surface was related to the spacing between the pillars and their size. It decreased with the decreasing of spacing between the pillars and the increasing of pillar size. A reduction in friction force was attributed to the reduced area of contact between patterned surface and colloidal probe. Additionally, the average friction force increased with increasing applied load and sliding velocity.

  2. Constraints on the symmetry energy from observational probes of the neutron star crust

    International Nuclear Information System (INIS)

    Newton, William G.; Hooker, Joshua; Gearheart, Michael; Fattoyev, Farrukh J.; Li, Bao-An; Murphy, Kyleah; Wen, De-Hua

    2014-01-01

    A number of observed phenomena associated with individual neutron star systems or neutron star populations find explanations in models in which the neutron star crust plays an important role. We review recent work examining the sensitivity to the slope of the symmetry energy L of such models, and constraints extracted on L from confronting them with observations. We focus on six sets of observations and proposed explanations: (i) The cooling rate of the neutron star in Cassiopeia A, confronting cooling models which include enhanced cooling in the nuclear pasta regions of the inner crust; (ii) the upper limit of the observed periods of young X-ray pulsars, confronting models of magnetic field decay in the crust caused by the high resistivity of the nuclear pasta layer; (iii) glitches from the Vela pulsar, confronting the paradigm that they arise due to a sudden recoupling of the crustal neutron superfluid to the crustal lattice after a period during which they were decoupled due to vortex pinning; (iv) the frequencies of quasi-periodic oscillations in the X-ray tail of light curves from giant flares from soft gamma-ray repeaters, confronting models of torsional crust oscillations; (v) the upper limit on the frequency to which millisecond pulsars can be spun-up due to accretion from a binary companion, confronting models of the r-mode instability arising above a threshold frequency determined in part by the viscous dissipation timescale at the crust-core boundary; and (vi) the observations of precursor electromagnetic flares a few seconds before short gamma-ray bursts, confronting a model of crust shattering caused by resonant excitation of a crustal oscillation mode by the tidal gravitational field of a companion neutron star just before merger. (orig.)

  3. Constraints on the symmetry energy from observational probes of the neutron star crust

    Energy Technology Data Exchange (ETDEWEB)

    Newton, William G.; Hooker, Joshua; Gearheart, Michael; Fattoyev, Farrukh J.; Li, Bao-An [Texas A and M University-Commerce, Department of Physics and Astronomy, Commerce (United States); Murphy, Kyleah [Texas A and M University-Commerce, Department of Physics and Astronomy, Commerce (United States); Umpqua Community College, Roseburg, Oregon (United States); Wen, De-Hua [Texas A and M University-Commerce, Department of Physics and Astronomy, Commerce (United States); South China University of Technology, Department of Physics, Guangzhou (China)

    2014-02-15

    A number of observed phenomena associated with individual neutron star systems or neutron star populations find explanations in models in which the neutron star crust plays an important role. We review recent work examining the sensitivity to the slope of the symmetry energy L of such models, and constraints extracted on L from confronting them with observations. We focus on six sets of observations and proposed explanations: (i) The cooling rate of the neutron star in Cassiopeia A, confronting cooling models which include enhanced cooling in the nuclear pasta regions of the inner crust; (ii) the upper limit of the observed periods of young X-ray pulsars, confronting models of magnetic field decay in the crust caused by the high resistivity of the nuclear pasta layer; (iii) glitches from the Vela pulsar, confronting the paradigm that they arise due to a sudden recoupling of the crustal neutron superfluid to the crustal lattice after a period during which they were decoupled due to vortex pinning; (iv) the frequencies of quasi-periodic oscillations in the X-ray tail of light curves from giant flares from soft gamma-ray repeaters, confronting models of torsional crust oscillations; (v) the upper limit on the frequency to which millisecond pulsars can be spun-up due to accretion from a binary companion, confronting models of the r-mode instability arising above a threshold frequency determined in part by the viscous dissipation timescale at the crust-core boundary; and (vi) the observations of precursor electromagnetic flares a few seconds before short gamma-ray bursts, confronting a model of crust shattering caused by resonant excitation of a crustal oscillation mode by the tidal gravitational field of a companion neutron star just before merger. (orig.)

  4. Associated-particle sealed-tube neutron probe for nonintrusive inspection

    International Nuclear Information System (INIS)

    Rhodes, E.; Dickerman, C.E.

    1997-01-01

    The development and investigation of a small associated-particle sealed-tube neutron generator (APSTNG) show potential for the associated-particle method to move out of the laboratory into field applications. This paper is a review of ANL investigations of this technology. Alpha particles associated with 14-MeV neutrons generated from the D-T reaction travel in the opposite direction and are detected inside the sealed tube. Gamma-ray spectra of resulting neutron reactions in the inspected volume encompassed by the alpha-detector solid angle identify many nuclides. Flight-times determined from detection times of the gamma rays and alpha particles separate the prompt and delayed gamma-rays and can yield a separate coarse tomographic image of each identified nuclide, from a single orientation without collimation. A continuous ion beam allows data acquisition by relatively low-bandwidth electronics. When a compact sealed-tube neutron generator is used, a relatively small and easily maintainable inspection system can be developed, that is rugged enough to be transportable. Proof-of-concept laboratory experiments have been performed for simulated explosives, drugs, special nuclear materials, and chemical warfare agents. Efficient collection of maximum information from each detected neutron with low background rates can allow a much lower source intensity than pulsed accelerator methods and yield a preference for an APSTNG system, when it can provide adequate usable source intensity. Based on lessons learned with the present system, an advanced APSTNG system is being designed and built that will be transportable and yield substantial increases in neutron output and target lifetime. copyright 1997 American Institute of Physics

  5. Associated-particle sealed-tube neutron probe for nonintrusive inspection

    International Nuclear Information System (INIS)

    Rhodes, E.; Dickerman, C.E.

    1996-01-01

    The development and investigation of a small associated-particle sealed-tube neutron generator (APSTNG) show potential to allow the associated-particle method to be moved out of the laboratory into field applications. Alpha particles associated with 14 MeV neutrons generated from the D-T reaction travel in the opposite direction and are detected inside the sealed tube. Gamma-ray spectra of resulting neutron reactions in the inspected volume encompassed by the alpha- detector solid angle identify many nuclides. Flight-times determined from detection times of the gamma-rays and alpha-particles not only separate the prompt and delayed gamma-rays but can also yield a separate coarse tomographic image of each identified nuclide, from a single orientation without collimation. A continuous ion beam allows data acquisition by relatively low-bandwidth commercial electronics. This efficient collection of maximum information from each detected neutron by the associated-particle method can allow a much lower source intensity than pulsed accelerator methods, provided a sufficient usable signal rate is obtained. When this method is coupled with a compact sealed-tube neutron generator, a relatively small, inexpensive, reliable, and easily maintainable inspection system can be developed, that is rugged enough to be transportable. Proof-of- concept laboratory experiments have been performed for simulated explosives, drugs, special nuclear materials, and chemical warfare agents. Based on lessons learned with the present APSTNG system, an advanced APSTNG system is being designed and built that will be transportable, yield a substantial neutron output increase, and provide a substantially improved target lifetime

  6. Theory study of global density influence and soils chemical composition at neutron probes response

    International Nuclear Information System (INIS)

    Crispino, M.L.

    1980-06-01

    Three energy group diffusion theory is applied to calculate the thermal neutron flux through a soil-water mixture at the neutron source. The soils studies are taken from two horizons of different composition, of a representative soil of the Litoral-Mata Zone of Pernambuco State. The thermal flux is obtained taking into consideration increasing values of the water volume percent, H, and the bulk density of the soil. The cross-sections of the mixture are calculated from the chemical composition of the soils. (author)

  7. Diabatic emission of neutrons: A probe for the energy dissipation mechanism in nucleus-nucleus collisions

    International Nuclear Information System (INIS)

    Noerenberg, W.; Cassing, W.

    1984-05-01

    The precompound emission of neutrons in central nucleus-nucleus collisions is investigated within the framework of dissipative diabatic dynamics. For 92 Mo + 92 Mo at bombarding energies between 7.5 and 20 MeV/u the differential neutron multiplicities dMsub(n)/dEsub(n) are estimated from the decay of highly excited diabatic single-particle states. The energy spectra have an almost exponential high-energy tail with effective temperatures up to 10 MeV for 20 MeV/u bombarding energy. (orig.)

  8. Surface Properties of a Nanocrystalline Fe-Ni-Nb-B Alloy After Neutron Irradiation

    Science.gov (United States)

    Pavùk, Milan; Sitek, Jozef; Sedlačková, Katarína

    2014-09-01

    The effect of neutron radiation on the surface properties of the nanocrystalline (Fe0.25Ni0.75)81Nb7B12 alloy was studied. Firstly, amorphous (Fe0.25Ni0.75)81Nb7B12 ribbon was brought by controlled annealing to the nanocrystalline state. After annealing, the samples of the nanocrystalline ribbon were irradiated in a nuclear reactor with neutron fluences of 1×1016cm-2 and 1 × 1017cm-2 . By utilizing the magnetic force microscopy (MFM), topography and a magnetic domain structure were recorded at the surface of the ribbon-shaped samples before and after irradiation with neutrons. The results indicate that in terms of surface the nanocrystalline (Fe0.25Ni0.75)81Nb7B12 alloy is radiation-resistant up to a neutron fluence of 1 × 1017cm-2 . The changes in topography observed for both irradiated samples are discussed

  9. Surface adhesion properties of graphene and graphene oxide studied by colloid-probe atomic force microscopy

    International Nuclear Information System (INIS)

    Ding Yanhuai; Zhang Ping; Ren Huming; Zhuo Qin; Yang Zhongmei; Jiang Xu; Jiang Yong

    2011-01-01

    Surface adhesion properties are important to various applications of graphene-based materials. Atomic force microscopy is powerful to study the adhesion properties of samples by measuring the forces on the colloidal sphere tip as it approaches and retracts from the surface. In this paper we have measured the adhesion force between the colloid probe and the surface of graphene (graphene oxide) nanosheet. The results revealed that the adhesion force on graphene and graphene oxide surface were 66.3 and 170.6 nN, respectively. It was found the adhesion force was mainly determined by the water meniscus, which was related to the surface contact angle of samples.

  10. Controlled Clustering of Gold Nanoparticles using Solid-support for Surface-enhanced Raman Spectroscopic Probes

    International Nuclear Information System (INIS)

    Chang, Hyejin; Chae, Jinjoo; Jeong, Hong; Kang, Homan; Lee, Yoonsik

    2014-01-01

    We fabricated small clusters of gold nanoparticles by using solid-supported aggregation of gold nanoparticles. The fabricated Au nanoclusters consisting mainly of dimers showed homogeneous characteristics in cluster size and SERS intensity. The SERS enhancement of 4-ABT molecules in an effective area within 2-nm gap appeared to be approximately 10. Detachment process by ultrasonication was successively carried out in order to use the nanoclusters as SERS probes. The possibility of these clusters as SERS probe was proved in terms of signal and cluster size. Single molecule-level sensitivity of surface-enhanced Raman scattering (SERS) was known approximately fifteen years ago. Ever since there have been many different applications benefiting from the ultra-high sensitivity such as single molecule detection, chemical sensing and bio-molecular probes. Especially, SERS has drawn much attention in bio-multiplexing probes owing to its unique optical characteristics claiming extremely narrow bandwidth, high sensitivity of light signals, and non-bleaching feature

  11. Controlled Clustering of Gold Nanoparticles using Solid-support for Surface-enhanced Raman Spectroscopic Probes

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hyejin; Chae, Jinjoo; Jeong, Hong [Department of Chemistry Education, Seoul (Korea, Republic of); Kang, Homan; Lee, Yoonsik [Interdisciplinary Program in Nano-Science and Technology, Pohang (Korea, Republic of)

    2014-03-15

    We fabricated small clusters of gold nanoparticles by using solid-supported aggregation of gold nanoparticles. The fabricated Au nanoclusters consisting mainly of dimers showed homogeneous characteristics in cluster size and SERS intensity. The SERS enhancement of 4-ABT molecules in an effective area within 2-nm gap appeared to be approximately 10. Detachment process by ultrasonication was successively carried out in order to use the nanoclusters as SERS probes. The possibility of these clusters as SERS probe was proved in terms of signal and cluster size. Single molecule-level sensitivity of surface-enhanced Raman scattering (SERS) was known approximately fifteen years ago. Ever since there have been many different applications benefiting from the ultra-high sensitivity such as single molecule detection, chemical sensing and bio-molecular probes. Especially, SERS has drawn much attention in bio-multiplexing probes owing to its unique optical characteristics claiming extremely narrow bandwidth, high sensitivity of light signals, and non-bleaching feature.

  12. In vitro study of proteins surface activity by tritium probe

    International Nuclear Information System (INIS)

    Chernysheva, M.G.; Badun, G.A.

    2010-01-01

    A new technique for in vitro studies of biomacromolecules interactions, their adsorption at aqueous/organic liquid interfaces and distribution in the bulk of liquid/liquid systems was developed. The method includes (1) tritium labeling of biomolecules by tritium thermal activation method and (2) scintillation phase step with organic phase, which can be concerned as a model of cellular membrane. Two globular proteins lysozyme and human serum albumin tested. We have determined the conditions of tritium labeling when labeled by-products can be easy separated by means of dialysis and size-exclusion chromatography. Scintillation phase experiments were conducted for three types of organic liquids. Thus, the influences of the nature of organic phase on proteins adsorption and its distribution in the bulk of aqueous/organic liquid system were determined. It was found that proteins possess high surface activity at aqueous/organic liquid interface. Furthermore, values of hydrophobicity of globular proteins were found by the experiment. (author)

  13. Inspection of Pipe Inner Surface using Advanced Pipe Crawler Robot with PVDF Sensor based Rotating Probe

    Directory of Open Access Journals (Sweden)

    Vimal AGARWAL

    2011-04-01

    Full Text Available Due to corrosive environment, pipes used for transportation of water and gas at the plants often get damaged. Defects caused by corrosion and cracking may cause serious accidents like leakage, fire and blasts. It also reduces the life of the transportation system substantially. In order to inspect such defects, a Polyvinyledene Fluoride (PVDF based cantilever smart probe is developed to scan the surface quality of the pipes. The smart probe, during rotation, touches the inner surface of the pipe and experience a broad-band excitation in the absence of surface features. On the other hand, whenever the probe comes across any surface projection, there is a change in vibration pattern of the probe, which causes a high voltage peak/pulse. Such peaks/pulses could give useful information about the location and nature of a defect. Experiments are carried out on different patterns, sizes and shapes of surface projections artificially constructed inside the pipe. The sensor system has reliably predicted the presence and distribution of projections in every case. It is envisaged that the new sensing system could be used effectively for pipe health monitoring.

  14. Probing the crust of the neutron star in EXO 0748-676

    Energy Technology Data Exchange (ETDEWEB)

    Degenaar, N.; Miller, J. M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Medin, Z. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Cumming, A. [Department of Physics, McGill University, 3600 rue University, Montreal, QC H3A 2T8 (Canada); Wijnands, R. [Astronomical Institute Anton Pannekoek, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Wolff, M. T. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Cackett, E. M. [Department of Physics and Astronomy, Wayne State University, 666 West Hancock Street, Detroit, MI 48201 (United States); Jonker, P. G. [SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht (Netherlands); Homan, J. [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Brown, E. F., E-mail: degenaar@umich.edu [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

    2014-08-10

    X-ray observations of quiescent X-ray binaries have the potential to provide insight into the structure and the composition of neutron stars. EXO 0748-676 had been actively accreting for over 24 yr before its outburst ceased in late 2008. Subsequent X-ray monitoring revealed a gradual decay of the quiescent thermal emission that can be attributed to cooling of the accretion-heated neutron star crust. In this work, we report on new Chandra and Swift observations that extend the quiescent monitoring to ≅5 yr post-outburst. We find that the neutron star temperature remained at ≅117 eV between 2009 and 2011, but had decreased to ≅110 eV in 2013. This suggests that the crust has not fully cooled yet, which is supported by the lower temperature (≅95 eV) measured ≅4 yr prior to the accretion phase in 1980. Comparing the data to thermal evolution simulations reveals that the apparent lack of cooling between 2009 and 2011 could possibly be a signature of convection driven by phase separation of light and heavy nuclei in the outer layers of the neutron star.

  15. In situ neutron depth profiling: A powerful method to probe lithium transport in micro-batteries

    NARCIS (Netherlands)

    Oudenhoven, J.F.M.; Labohm, F.; Mulder, M.; Niessen, R.A.H.; Mulder, F.M.; Notten, P.H.L.

    2011-01-01

    In situ neutron depth profiling (NDP) offers the possibility to observe lithium transport inside micro-batteries during battery operation. It is demonstrated that NDP results are consistent with the results of electrochemical measurements, and that the use of an enriched6LiCoO2 cathode offers more

  16. Neutron radiative capture methods for surface elemental analysis

    Science.gov (United States)

    Trombka, J.I.; Senftle, F.; Schmadebeck, R.

    1970-01-01

    Both an accelerator and a 252Cf neutron source have been used to induce characteristic gamma radiation from extended soil samples. To demonstrate the method, measurements of the neutron-induced radiative capture and activation gamma rays have been made with both Ge(Li) and NaI(Tl) detectors, Because of the possible application to space flight geochemical analysis, it is believed that NaI(Tl) detectors must be used. Analytical procedures have been developed to obtain both qualitative and semiquantitative results from an interpretation of the measured NaI(Tl) pulse-height spectrum. Experiment results and the analytic procedure are presented. ?? 1970.

  17. Mixing of alcohol and water molecules studied by neutron probe. Structure and dynamics

    International Nuclear Information System (INIS)

    Yoshida, Koji

    2001-01-01

    Structure of water/alcohol mixing solution was studied by three methods such as an isotope-exchanged neutron scattering method, RISM (Reference Interaction Site Model) integral equation and a neutron spin echo method. The principle of methods, experiments and results were reported. The results of experiments of water/tert-butyl alcohol (TBA) solution by the isotope-exchange neutron scattering method showed TBA molecule associated with each other through end methyl group. Especially this effect was the largest at x TBA = 0.06 and decreased with increasing the concentration of TBA. However, hydrogen bonding of TBA was very rare at x TBA = 0.06. By the partial radial distribution function obtained from RISM integral equation, it indicated that the structure of pure TBA became chain structure by hydrogen bond but changed to the structure contacted directly each hydrophobic group with increasing the concentration of water. Water/2-butoxyethanol (BE) mixing solution was measured by a neutron spin echo method. The activation energy of the diffusion coefficients obtained agreed to the energy of hydrogen bonding. The temperature response of diffusion coefficients showed the inverse of the experimental results obtained by the dynamic light scattering method. The difference between two measurement methods was different time scale and space scale. Namely, the object of the neutron scattering method is nano meter and nano second, but one of light scattering method many times over. It was proved from the above results that there was the cluster consisted of the same kind of molecule in the homogeneous two components solution, but the cluster was not stable and constantly exchanged with molecule, where the production and decay of the cluster is repeated at about nano sec. (S.Y.)

  18. Probing Ultrafast Electron Dynamics at Surfaces Using Soft X-Ray Transient Reflectivity Spectroscopy

    Science.gov (United States)

    Baker, L. Robert; Husek, Jakub; Biswas, Somnath; Cirri, Anthony

    The ability to probe electron dynamics with surface sensitivity on the ultrafast time scale is critical for understanding processes such as charge separation, injection, and surface trapping that mediate efficiency in catalytic and energy conversion materials. Toward this goal, we have developed a high harmonic generation (HHG) light source for femtosecond soft x-ray reflectivity. Using this light source we investigated the ultrafast carrier dynamics at the surface of single crystalline α-Fe2O3, polycrystalline α-Fe2O3, and the mixed metal oxide, CuFeO2. We have recently demonstrated that CuFeO2 in particular is a selective catalyst for photo-electrochemical CO2 reduction to acetate; however, the role of electronic structure and charge carrier dynamics in mediating catalytic selectivity has not been well understood. Soft x-ray reflectivity measurements probe the M2,3, edges of the 3d transition metals, which provide oxidation and spin state resolution with element specificity. In addition to chemical state specificity, these measurements are also surface sensitive, and by independently simulating the contributions of the real and imaginary components of the complex refractive index, we can differentiate between surface and sub-surface contributions to the excited state spectrum. Accordingly, this work demonstrates the ability to probe ultrafast carrier dynamics in catalytic materials with element and chemical state specificity and with surface sensitivity.

  19. The electrical double layer on gold probed by electrokinetic and surface force measurements

    NARCIS (Netherlands)

    Giesbers, M.; Kleijn, J.M.; Cohen Stuart, M.A.

    2002-01-01

    Gold surfaces, obtained by vacuum deposition of 15-nm gold films on glass and silica wafers, were studied in aqueous solutions by streaming potential measurements and colloidal-probe AFM force measurements. In the force measurements both a bare and a gold-coated silica particle (6 m in diameter)

  20. Probing shape coexistence in neutron-deficient $^{72}$Se via low-energy Coulomb excitation

    CERN Multimedia

    We propose to study the evolution of nuclear structure in neutron-­deficient $^{72}$Se by performing a low-­energy Coulomb excitation measurement. Matrix elements will be determined for low-­lying excited states allowing for a full comparison with theoretical predictions. Furthermore, the intrinsic shape of the ground state, and the second 0$^{+}$ state, will be investigated using the quadrupole sum rules method.

  1. Neutron emission as a probe of fusion-fission and quasi-fission dynamics

    International Nuclear Information System (INIS)

    Hinde, D.J.

    1991-01-01

    Pre- and post scission neutron yeilds have been measured as a function of projectile mass, compound nucleus fissility, and fission mass-split and total kinetic energy (TKE) for 27 fusion-fission and quasi-fission reactions induced by beams of 16,18 O, 40 Ar and 64 Ni. A new method of interpretation of experimental pre-scission neutron multiplicities ν-pre and mean kinetic energies ε ν allows the extraction of fission time scales with much less uncertainty than previously, all fusion-fission results being consistent with a dynamical time scale of (35±15) x 10 -21 s for symmetric fission. All reactions show that ν-pre falls quite rapidly with increasing mass-asymmetry; evidence is presented that for fusion-fission reactions this is partly due to a reduction of the dynamical fission time scale with mass-asymmetry. For quasi-fission, the data indicate that the pre-scission multiplicity and mean neutron kinetic energy are very sensitive to the final mass-asymmetry, but that the time scale is virtually independent of mass-asymmetry. It is concluded that for fusion-fission there is no dependence of ν-pre on TKE, whilst for 64 Ni-induced quasi-fission reactions, a strong increase of ν-pre with decreasing TKE is observed, probably largely caused by neutron emission during the acceleration time of the fission fragments in these fast reactions. Interpretation of post-scission multiplicities in terms of fragment excitation energies leads to deduced time scales consistent with those determined from the pre-scission data. 54 refs., 17 tabs., 25 figs

  2. Surface damage in the small intestine of the mouse after X - or neutron irradiation

    International Nuclear Information System (INIS)

    Hamlet, R.; Carr, K.E.; Nias, A.H.; Watt, C.

    1981-01-01

    Damage after X-irradiation includes lateral villous collapse, progressing after 3 - 5 days to villi which sometimes show signs of vertical collapse. After neutron irradiation vertical villous collapse is established earlier, with less swelling of villous tips. It seems, therefore, that at radiobiologically equivalent doses, neutron and X-irradiation produce different levels of surface damage, with neutron irradiation being the more destructive. Early villous tip damage may perhaps be due to disruption of susceptible cells already at the extrusion zone, or to stromal damage

  3. Pressure/temperature fluid cell apparatus for the neutron powder diffractometer instrument: Probing atomic structure in situ

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hsiu-Wen; Fanelli, Victor R.; Reiche, Helmut M.; Larson, Eric; Taylor, Mark A.; Siewenie, Joan [Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Xu, Hongwu [Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Zhu, Jinlong [High Pressure Science and Engineering Center, Department of Physics and Astronomy, The University of Nevada, Las Vegas, Nevada 89154, USA and National Lab for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Page, Katharine, E-mail: pagekl@ornl.gov [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2014-12-15

    This contribution describes a new local structure compatible gas/liquid cell apparatus for probing disordered materials at high pressures and variable temperatures in the Neutron Powder Diffraction instrument at the Lujan Neutron Scattering Center, Los Alamos National Laboratory. The new sample environment offers choices for sample canister thickness and canister material type. Finite element modeling is utilized to establish maximum allowable working pressures of 414 MPa at 15 K and 121 MPa at 600 K. High quality atomic pair distribution function data extraction and modeling have been demonstrated for a calibration standard (Si powder) and for supercritical and subcritical CO{sub 2} measurements. The new sample environment was designed to specifically target experimental studies of the local atomic structures involved in geologic CO{sub 2} sequestration, but will be equally applicable to a wide variety of energy applications, including sorption of fluids on nano/meso-porous solids, clathrate hydrate formation, catalysis, carbon capture, and H{sub 2} and natural gas uptake/storage.

  4. Neutron star mergers as a probe of modifications of general relativity with finite-range scalar forces

    Science.gov (United States)

    Sagunski, Laura; Zhang, Jun; Johnson, Matthew C.; Lehner, Luis; Sakellariadou, Mairi; Liebling, Steven L.; Palenzuela, Carlos; Neilsen, David

    2018-03-01

    Observations of gravitational radiation from compact binary systems provide an unprecedented opportunity to test general relativity in the strong field dynamical regime. In this paper, we investigate how future observations of gravitational radiation from binary neutron star mergers might provide constraints on finite-range forces from a universally coupled massive scalar field. Such scalar degrees of freedom (d.o.f.) are a characteristic feature of many extensions of general relativity. For concreteness, we work in the context of metric f (R ) gravity, which is equivalent to general relativity and a universally coupled scalar field with a nonlinear potential whose form is fixed by the choice of f (R ). In theories where neutron stars (or other compact objects) obtain a significant scalar charge, the resulting attractive finite-range scalar force has implications for both the inspiral and merger phases of binary systems. We first present an analysis of the inspiral dynamics in Newtonian limit, and forecast the constraints on the mass of the scalar and charge of the compact objects for the Advanced LIGO gravitational wave observatory. We then perform a comparative study of binary neutron star mergers in general relativity with those of a one-parameter model of f (R ) gravity using fully relativistic hydrodynamical simulations. These simulations elucidate the effects of the scalar on the merger and postmerger dynamics. We comment on the utility of the full waveform (inspiral, merger, postmerger) to probe different regions of parameter space for both the particular model of f (R ) gravity studied here and for finite-range scalar forces more generally.

  5. A time-of-flight neutron reflectometer for surface and interfacial studies

    International Nuclear Information System (INIS)

    Penfold, J.; Ward, R.C.; Williams, W.G.

    1987-03-01

    A time-of-flight neutron reflectometer constructed for surface and interfacial studies, and installed at the ISIS pulsed neutron source, is described. One of its important design features is its inclined incident beam, since this allows both liquid and solid surface phenomena to be investigated. Measurements are presented to show the performance of the instrument, and new representative results, which include studies of liquid surfaces, Langmuir-Blodgett films, and thin film multilayers, are included as illustrations of the scientific potential of the method. (author)

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

    International Nuclear Information System (INIS)

    Stockmeyer, R.

    1976-01-01

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

  7. Irradiation-induced precipitates in a neutron irradiated 304 stainless steel studied by three-dimensional atom probe

    Energy Technology Data Exchange (ETDEWEB)

    Toyama, T., E-mail: ttoyama@imr.tohoku.ac.jp [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Narita-cho 2145-2, Oarai, Ibaraki 311-1313 (Japan); Nozawa, Y. [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Narita-cho 2145-2, Oarai, Ibaraki 311-1313 (Japan); Van Renterghem, W. [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, 2400 Mol (Belgium); Matsukawa, Y.; Hatakeyama, M.; Nagai, Y. [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Narita-cho 2145-2, Oarai, Ibaraki 311-1313 (Japan); Al Mazouzi, A. [EDF R and D, Avenue des Renardieres Ecuelles, 77818 Moret sur Loing Cedex (France); Van Dyck, S. [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, 2400 Mol (Belgium)

    2011-11-15

    Highlights: > Irradiation-induced precipitates in a 304 stainless steel were investigated by three-dimensional atom probe. > The precipitates were found to be {gamma}' precipitates (Ni{sub 3}Si). > Post-irradiation annealing was performed to discuss the contribution of the precipitates to irradiation-hardening. - Abstract: Irradiation-induced precipitates in a 304 stainless steel, neutron-irradiated to a dose of 24 dpa at 300 deg. C in the fuel wrapper plates of a commercial pressurized water reactor, were investigated by laser-assisted three-dimensional atom probe. A high number density of 4 x 10{sup 23} m{sup -3} of Ni-Si rich precipitates was observed, which is one order of magnitude higher than that of Frank loops. The average diameter was {approx}10 nm and the average chemical composition was 40% Ni, 14% Si, 11% Cr and 32% Fe in atomic percent. Over a range of Si concentrations, the ratio of Ni to Si was {approx}3, close to that of {gamma}' precipitate (Ni{sub 3}Si). In some precipitates, Mn enrichment inside the precipitate and P segregation at the interface were observed. Post-irradiation annealing was performed to discuss the contribution of the precipitates to irradiation-hardening.

  8. U-Shaped and Surface Functionalized Polymer Optical Fiber Probe for Glucose Detection.

    Science.gov (United States)

    Azkune, Mikel; Ruiz-Rubio, Leire; Aldabaldetreku, Gotzon; Arrospide, Eneko; Pérez-Álvarez, Leyre; Bikandi, Iñaki; Zubia, Joseba; Vilas-Vilela, Jose Luis

    2017-12-25

    In this work we show an optical fiber evanescent wave absorption probe for glucose detection in different physiological media. High selectivity is achieved by functionalizing the surface of an only-core poly(methyl methacrylate) (PMMA) polymer optical fiber with phenilboronic groups, and enhanced sensitivity by using a U-shaped geometry. Employing a supercontinuum light source and a high-resolution spectrometer, absorption measurements are performed in the broadband visible light spectrum. Experimental results suggest the feasibility of such a fiber probe as a low-cost and selective glucose detector.

  9. Probing the collectivity in neutron-rich Cd isotopes via γ-ray spectroscopy

    International Nuclear Information System (INIS)

    Naqvi, Farheen

    2011-01-01

    The spin and configurational structure of excited states of 127 Cd, 125 Cd and 129 Cd, having two proton and three, five and one neutron holes, respectively in the doubly magic 132 Sn core have been studied. The isomeric states in Cd isotopes were populated in the fragmentation of a 136 Xe beam at an energy of 750 MeV/u on a 9 Be target of 4 g/cm 2 . The experiment was performed at GSI Darmstadt. The neutron-rich Cd isotopes were selected using the Bρ - ΔE - Bρ method at the FRagment Separator (FRS). Event by event identification of fragments in terms of their A (mass) and Z (charge) was provided by the standard FRS detectors. The reaction residues were implanted in a plastic stopper surrounded by 15 Ge cluster detectors from the RISING array to detect the γ decays. In 127 Cd, an isomeric state with a half-life of 17.5(3) μs has been detected. This yrast (19/2) + isomer is proposed to have mixed proton-neutron configurations and to decay by two competing stretched M2 and E3 transitions. Experimental results are compared with the isotone 129 Sn. In 125 Cd, apart from the previously observed (19/2) + isomer, two new metastable states at 3896 keV and 2141 keV have been detected. A half-life of 13.6(2) μs was measured for the (19/2) + isomer, having a decay structure similar to the corresponding isomeric state in 127 Cd. The higher lying isomers have a half-life of 3.1(1) μs and 2.5(15) ns, respectively. Time distributions of delayed γ transitions and γγ-coincidence relations were exploited to construct decay schemes for the two nuclei. Comparison of the experimental data with shell-model calculations is also discussed. The new information provides input for the proton-neutron interaction in nuclei around the doubly magic 132 Sn core. The γ decays of the isomeric states in 129 Cd were not observed experimentally. The reasons for the non-observation of delayed γ rays for 129 Cd are either an isomeric half-life of less than 93 ns based on the experimentally

  10. Study on a New Ultraviolet Sterilizer to the Surface Disinfection of the Ultrasound Probe.

    Science.gov (United States)

    Chen, Gui Qiu; Chen, Yu Hao; Yi, Liang; Yin, Jin; Gao, Qiong; Song, Jiang Nan; Li, Shi Kang; Chen, Pei Hou; Guo, Gui Ping

    2018-02-01

    We studied the disinfection effect of a new ultraviolet (UV) sterilizer and its utilization on ultrasound probe surfaces. Carrier quantitative germicidal tests, simulated on-the-spot trials, and organic substance influence tests were used to carry out experimental observation. Artificially infected probes were disinfected using the sterilizer or a germicidal lamp for comparison. The total number and types of bacteria were determined and identified. Our results demonstrated the sterilizer had the best disinfection effect among three different disinfection methods in hospital. The sterilizer has been used in a hospital setting for 2 years with no notable damage to the ultrasound probe instrument. It has the advantages of fast disinfection, high disinfection effect, and good compatibility with the ultrasound instrument, worthy of being a promoted application in medical institutions. Copyright © 2018 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  11. Fabrication of Localized Surface Plasmon Resonance Fiber Probes Using Ionic Self-Assembled Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Miao Wan

    2010-07-01

    Full Text Available An nm-thickness composite gold thin film consisting of gold nanoparticles and polyelectrolytes is fabricated through ionic self-assembled multilayers (ISAM technique and is deposited on end-faces of optical fibers to construct localized surface plasmon resonance (LSPR fiber probes. We demonstrate that the LSPR spectrum induced by ISAM gold films can be fine-tuned through the ISAM procedure. We investigate variations of reflection spectra of the probe with respect to the layer-by-layer adsorption of ISAMs onto end-faces of fibers, and study the spectral variation mechanism. Finally, we demonstrated using this fiber probe to detect the biotin-streptavidin bioconjugate pair. ISAM adsorbed on optical fibers potentially provides a simple, fast, robust, and low-cost, platform for LSPR biosensing applications.

  12. A new capacitive/resistive probe method for studying magnetic surfaces

    International Nuclear Information System (INIS)

    Kitajima, Sumio; Takayama, Masakazu; Zama, Tatsuya; Takaya, Kazuhiro; Takeuchi, Nobunao; Watanabe, Hiroshige

    1991-01-01

    A new capacitive/resistive probe method for mapping the magnetic surfaces from resistance or capacitance between a magnetic surface and a vacuum vessel was developed and tested. Those resistances and capacitances can be regarded as components of a simple electrical bridge circuit. This method exploits electrical transient response of the bridge circuit for a square pulse. From equiresistance or equicapacitance points, the magnetic surface structure can be deduced. Measurements on the Tohoku University Heliac, which is a small-size standard heliac, show good agreement with numerical calculations. This method is particularly useful for pulse-operated machines. (author)

  13. THE COOLING OF THE CASSIOPEIA A NEUTRON STAR AS A PROBE OF THE NUCLEAR SYMMETRY ENERGY AND NUCLEAR PASTA

    Energy Technology Data Exchange (ETDEWEB)

    Newton, William G.; Hooker, Joshua; Li, Bao-An [Department of Physics and Astronomy, Texas A and M University-Commerce, Commerce, TX 75429-3011 (United States); Murphy, Kyleah [Umpqua Community College, Roseburg, OR 97470 (United States)

    2013-12-10

    X-ray observations of the neutron star (NS) in the Cas A supernova remnant over the past decade suggest the star is undergoing a rapid drop in surface temperature of ≈2%-5.5%. One explanation suggests the rapid cooling is triggered by the onset of neutron superfluidity in the core of the star, causing enhanced neutrino emission from neutron Cooper pair breaking and formation (PBF). Using consistent NS crust and core equations of state (EOSs) and compositions, we explore the sensitivity of this interpretation to the density dependence of the symmetry energy L of the EOS used, and to the presence of enhanced neutrino cooling in the bubble phases of crustal ''nuclear pasta''. Modeling cooling over a conservative range of NS masses and envelope compositions, we find L ≲ 70 MeV, competitive with terrestrial experimental constraints and other astrophysical observations. For masses near the most likely mass of M ≳ 1.65 M {sub ☉}, the constraint becomes more restrictive 35 ≲ L ≲ 55 MeV. The inclusion of the bubble cooling processes decreases the cooling rate of the star during the PBF phase, matching the observed rate only when L ≲ 45 MeV, taking all masses into consideration, corresponding to NS radii ≲ 11 km.

  14. Neutron scattering and muon spin rotation as probes of light interstitial transport

    International Nuclear Information System (INIS)

    Brown, D.W.

    1985-01-01

    The transport of light interstitials, specifically of hydrogen isotopes and the positive muon, is studied with the help of microscopic transport models. The principal observables are the differential neutron scattering cross section of the hydrogen isotopes and the muon spin rotation signal of the positive muon. The transport feature of primary interest is coherence arising as a result of persistence of quantum mechanical phase memory. Evaluation of observables is based on the generalized master equation, or alternatively, the stochastic Liouville equation. The latter is applied to obtain the neutron scattering lineshapes for local tunneling systems as well as for extended Bravais and non-Bravais lattices. It is found that the usual form of the stochastic Liouville equation does not address adequately transport among non-degenerate site-states. An appropriate modification is suggested and employed to obtain scattering lineshapes applicable to recent experiments on impurity-trapped hydrogen. The muon spin rotation signal is formulated under the assumption that spin interactions constitute a negligible source of scattering for muon transport. The depolarization function is evaluated for the cases of local tunneling systems and simple models of spatially extended transport. The former addresses consequences of coherence and both address the consequences of the spatial extent of the muon wavefunction. It is found that the depolarization function is sensitive to the wave function extent, and the detail attributable to it is characterized

  15. Precision Measurement of the Neutron Twist-3 Matrix Element dn2: Probing Color Forces

    Energy Technology Data Exchange (ETDEWEB)

    Posik, Matthew; Flay, David; Parno, Diana; Allada, Kalyan; Armstrong, Whitney; Averett, Todd; Benmokhtar, Fatiha; Bertozzi, William; Camsonne, Alexandre; Canan, Mustafa; Cates, Gordon; Chen, Chunhua; Chen, Jian-Ping; Choi, Seonho; Chudakov, Eugene; Cusanno, Francesco; Dalton, Mark; Deconinck, Wouter; De Jager, Cornelis; Deng, Xiaoyan; Deur, Alexandre; Dutta, Chiranjib; El Fassi, Lamiaa; Franklin, Gregg; Friend, Megan; Gao, Haiyan; Garibaldi, Franco; Gilad, Shalev; Gilman, Ronald; Glamazdin, Oleksandr; Golge, Serkan; Gomez, Javier; Guo, Lei; Hansen, Jens-Ole; Higinbotham, Douglas; Holmstrom, Timothy; Huang, J; Hyde, Charles; Ibrahim Abdalla, Hassan; Jiang, Xiaodong; Jin, Ge; Katich, Joseph; Kelleher, Aidan; Kolarkar, Ameya; Korsch, Wolfgang; Kumbartzki, Gerfried; LeRose, John; Lindgren, Richard; Liyanage, Nilanga; Long, Elena; Lukhanin, Oleksandr; Mamyan, Vahe; McNulty, Dustin; Meziani, Zein-Eddine; Michaels, Robert; Mihovilovic, Miha; Moffit, Bryan; Muangma, Navaphon; Nanda, Sirish; Narayan, Amrendra; Nelyubin, Vladimir; Norum, Blaine; Nuruzzaman, nfn; Oh, Yongseok; Peng, Jen-chieh; Qian, Xin; Qiang, Yi; Rakhman, Abdurahim; Riordan, Seamus; Saha, Arunava; Sawatzky, Bradley; Hashemi Shabestari, Mitra; Shahinyan, Albert; Sirca, Simon; Solvignon-Slifer, Patricia; Subedi, Ramesh; Sulkosky, Vincent; Tobias, William; Troth, Wolfgang; Wang, Diancheng; Wang, Y; Wojtsekhowski, Bogdan; Yan, X; Yao, Huan; Ye, Yunxiu; Ye, Zhihong; Yuan, Lulin; Zhan, X; Zhang, Y; Zhang, Y -W; Zhao, Bo; Zheng, Xiaochao

    2014-07-01

    Double-spin asymmetries and absolute cross sections were measured at large Bjorken x (0.25 lte x lte 0.90), in both the deep-inelastic and resonance regions, by scattering longitudinally polarized electrons at beam energies of 4.7 and 5.9 GeV from a transversely and longitudinally polarized 3He target. In this dedicated experiment, the spin structure function g2 on 3He was determined with precision at large x, and the neutron twist-three matrix element dn2 was measured at ?Q2? of 3.21 and 4.32 GeV2/c2, with an absolute precision of about 10?5. Our results are found to be in agreement with lattice QCD calculations and resolve the disagreement found with previous data at ?Q2?= 5 GeV2/c2. Combining dn2 and a newly extracted twist-four matrix element, fn2, the average neutron color electric and magnetic forces were extracted and found to be of opposite sign and about 60 MeV/fm in magnitude.

  16. Pump-probe surface photovoltage spectroscopy measurements on semiconductor epitaxial layers

    International Nuclear Information System (INIS)

    Jana, Dipankar; Porwal, S.; Sharma, T. K.; Oak, S. M.; Kumar, Shailendra

    2014-01-01

    Pump-probe Surface Photovoltage Spectroscopy (SPS) measurements are performed on semiconductor epitaxial layers. Here, an additional sub-bandgap cw pump laser beam is used in a conventional chopped light geometry SPS setup under the pump-probe configuration. The main role of pump laser beam is to saturate the sub-bandgap localized states whose contribution otherwise swamp the information related to the bandgap of material. It also affects the magnitude of Dember voltage in case of semi-insulating (SI) semiconductor substrates. Pump-probe SPS technique enables an accurate determination of the bandgap of semiconductor epitaxial layers even under the strong influence of localized sub-bandgap states. The pump beam is found to be very effective in suppressing the effect of surface/interface and bulk trap states. The overall magnitude of SPV signal is decided by the dependence of charge separation mechanisms on the intensity of the pump beam. On the contrary, an above bandgap cw pump laser can be used to distinguish the signatures of sub-bandgap states by suppressing the band edge related feature. Usefulness of the pump-probe SPS technique is established by unambiguously determining the bandgap of p-GaAs epitaxial layers grown on SI-GaAs substrates, SI-InP wafers, and p-GaN epilayers grown on Sapphire substrates

  17. A cell-surface-anchored ratiometric fluorescent probe for extracellular pH sensing.

    Science.gov (United States)

    Ke, Guoliang; Zhu, Zhi; Wang, Wei; Zou, Yuan; Guan, Zhichao; Jia, Shasha; Zhang, Huimin; Wu, Xuemeng; Yang, Chaoyong James

    2014-09-10

    Accurate sensing of the extracellular pH is a very important yet challenging task in biological and clinical applications. This paper describes the development of an amphiphilic lipid-DNA molecule as a simple yet useful cell-surface-anchored ratiometric fluorescent probe for extracellular pH sensing. The lipid-DNA probe, which consists of a hydrophobic diacyllipid tail and a hydrophilic DNA strand, is modified with two fluorescent dyes; one is pH-sensitive as pH indicator and the other is pH-insensitive as an internal reference. The lipid-DNA probe showed sensitive and reversible response to pH change in the range of 6.0-8.0, which is suitable for most extracellular studies. In addition, based on simple hydrophobic interactions with the cell membrane, the lipid-DNA probe can be easily anchored on the cell surface with negligible cytotoxicity, excellent stability, and unique ratiometric readout, thus ensuring its accurate sensing of extracellular pH. Finally, this lipid-DNA-based ratiometric pH indicator was successfully used for extracellular pH sensing of cells in 3D culture environment, demonstrating the potential applications of the sensor in biological and medical studies.

  18. Uses of AES and RGA to study neutron-irradiation-enhanced segregation to internal surfaces

    International Nuclear Information System (INIS)

    Gessel, G.R.; White, C.L.

    1980-01-01

    The high flux of point defects to sinks during neutron irradiation can result in segregation of impurity or alloy additions to metals. Such segregants can be preexisting or produced by neutron-induced transmutations. This segregation is known to strongly influence swelling and mechanical properties. Over a period of years, facilities have been developed at ORNL incorporating AES and RGA to examine irradiated materials. Capabilities of this system include in situ tensile fracture at elevated temperatures under ultrahigh vacuum 10 -10 torr and helium release monitoring. AES and normal incidence inert ion sputtering are exploited to examine segregation at the fracture surface and chemical gradients near the surface

  19. Inspection of CF188 composite flight control surfaces with neutron radiography

    International Nuclear Information System (INIS)

    Lewis, W.J.; Bennett, L.G.I.; Mullin, S.K.

    1996-01-01

    At the Royal Military College of Canada's SLOWPOKE-2 Facility, a neutron radiography facility has been designed and installed using a small (20kWth), pool-type research reactor called the SLOWPOKE-2 (Safe Low Power c(K)ritical Experiment) as the neutron source. Since then, the research has continued along two fronts: developing applications and improving the quality of the neutron beam. The most interesting applications investigated to date has been the inspection of various metal ceramic composites and the inspection of the composite flight control surfaces of some of the CF188 Hornet aircraft. As part of the determination of the integrity of the aircraft, it was decided to inspect an aircraft with the highest flight house using both X- and neutron radiography. The neutron radiography and, to a lesser extent, X-radiography inspections completed at McClellan AFB revealed 93 anomalies. After returning to Canada, the component with the greatest structural significance, namely the right hand rudder from the vertical stabilizer, was removed from the aircraft and put through a rigorous program of numerous NDT inspections, including X-radiography (film and real-time), eddy current, ultrasonics (through transmission and pitch-catch), infrared thermography, and neutron radiography. Therefore, of all the techniques investigated, only through transmission ultrasonics and neutron radiography were able to identify large areas of hydration. However, only neutron radiography could identify the small areas of moisture and hydration. Given the structural significance of the flight control surfaces in modern fighter aircraft, even the smallest amounts of hydration could potentially lead to catastrophic results

  20. A precision measurement of the neutron2. Probing the color force

    Energy Technology Data Exchange (ETDEWEB)

    Posik, Matthew R. [Temple Univ., Philadelphia, PA (United States)

    2014-01-01

    The g2 nucleon spin-dependent structure function measured in electron deep inelastic scattering contains information beyond the simple parton model description of the nucleon. It provides insight into quark-gluon correlations and a path to access the confining local color force a struck quark experiences just as it is hit by the virtual photon due to the remnant di-quark. The quantity d2, a measure of this local color force, has its information encoded in an x2 weighted integral of a linear combination of spin structure functions g1 and g2 and thus is dominated by the valence-quark region at large momentum fraction x. To date, theoretical calculations and experimental measurements of the neutron d2 differ by about two standard deviations. Therefore, JLab experiment E06-014, performed in Hall A, made a precision measurement of this quantity at two mean four momentum transfers values of 3.21 and 4.32 GeV2. Double spin asymmetries and absolute cross-sections were measured in both DIS and resonance regions by scattering longitudinally polarized electrons at beam energies of 4.74 and 5.89 GeV from a longitudinally and transversely polarized 3He target. Results for the absolute cross-sections and spin structure functions on 3He will be presented in the dissertation, as well as results for the neutron d2 and extracted color forces.

  1. Friction as a probe of surface properties of a polymer glass

    OpenAIRE

    Bureau, Lionel

    2007-01-01

    We probe the temperature dependence of friction at the interface between a glassy poly(methylmethacrylate) lens and a flat substrate coated with a methyl-terminated self-assembled monolayer. The monolayer exhibits density defects which act as pinning sites for the polymer chains. We show that the shear response of such an interface supports the existence, at the surface of the glassy polymer, of a nanometer-thick layer of mobile chains. Friction can be ascribed to the interplay between viscou...

  2. Probing Enzyme-Surface Interactions via Protein Engineering and Single-Molecule Techniques

    Science.gov (United States)

    2017-06-26

    SECURITY CLASSIFICATION OF: The overall objective of this research was to exploit protein engineering and fluorescence single-molecule methods to...enhance our understanding of the interaction of proteins and surfaces. Given this objective, the specific aims of this research were to: 1) exploit the...incorporation of unnatural amino acids in proteins to introduce single-molecule probes (i.e., fluorophores for fluorescence resonance energy transfer

  3. Surfaces of colloidal PbSe nanocrystals probed by thin-film positron annihilation spectroscopy

    Directory of Open Access Journals (Sweden)

    L. Chai

    2013-08-01

    Full Text Available Positron annihilation lifetime spectroscopy and positron-electron momentum density (PEMD studies on multilayers of PbSe nanocrystals (NCs, supported by transmission electron microscopy, show that positrons are strongly trapped at NC surfaces, where they provide insight into the surface composition and electronic structure of PbSe NCs. Our analysis indicates abundant annihilation of positrons with Se electrons at the NC surfaces and with O electrons of the oleic ligands bound to Pb ad-atoms at the NC surfaces, which demonstrates that positrons can be used as a sensitive probe to investigate the surface physics and chemistry of nanocrystals inside multilayers. Ab initio electronic structure calculations provide detailed insight in the valence and semi-core electron contributions to the positron-electron momentum density of PbSe. Both lifetime and PEMD are found to correlate with changes in the particle morphology characteristic of partial ligand removal.

  4. Optical probe for porosity defect detection on inner diameter surfaces of machined bores

    Science.gov (United States)

    Kulkarni, Ojas P.; Islam, Mohammed N.; Terry, Fred L.

    2010-12-01

    We demonstrate an optical probe for detection of porosity inside spool bores of a transmission valve body with diameters down to 5 mm. The probe consists of a graded-index relay rod that focuses a laser beam spot onto the inner surface of the bore. Detectors, placed in the specular and grazing directions with respect to the incident beam, measure the change in scattered intensity when a surface defect is encountered. Based on the scattering signatures in the two directions, the system can also validate the depth of the defect and distinguish porosity from bump-type defects coming out of the metal surface. The system can detect porosity down to a 50-μm lateral dimension and ~40 μm in depth with >3-dB contrast over the background intensity fluctuations. Porosity detection systems currently use manual inspection techniques on the plant floor, and the demonstrated probe provides a noncontact technique that can help automotive manufacturers meet high-quality standards during production.

  5. Research and Training of Using Neutron Scattering to Probe the Collective Phenomena in Doped Transition-Metal Oxides. Final report

    International Nuclear Information System (INIS)

    Zhang, Jiandi

    2008-01-01

    The objective of this funded research program include: explore and understand the microscopic origins of collective phenomena in doped transition-metal oxides (TMOs) using neutrons as one of the primary tools, and train new generation of neutron scatters and collaborate with Oak Ridge National Lab in both materials synthesis and characterization. The major physics issues focused on in this project consist of the microscopic correlations between lattice structure and magnetic ordering, the nature of elementary lattice and spin excitations, the origin of nanometer-scale phase separations, and the effects of dimensional confinement and broken symmetry. The main materials are doped TMOs grown as single crystals by a floating-zone technique at ORNL as well as multiplayer films grown with a laser-MBE facility at Florida International University (FIU). Our educational objective is the training of our graduate and undergraduate students, especially Hispanic and other minority students, to use neutrons as a probe for materials research by taking advantage of national neutron facilities and to grow novel materials by using the floating-zone and laser-MBE technique. The main achievements of the project include the systematic study of the spin dynamics, especially the spin wave excitations in ferromagnetic manganites; the discovery of the critical doping concentration for the magnetic phase separation of the charge-ordered state in Pr 1-x Ca x MnO 3 - ; the study of Σ 4 phonon softening associated with the lattice instability near the quantum critical point as well as the discovery of an anomalous mode in single-layered ruthenates. These results gain some important insights into the collective excitations in both spin and lattice degrees of freedom as well as their close coupling in these correlated TMO systems. Furthermore, this project also accomplished the synthesis and some characterization of the single crystals of a new material Ba 2-x Sr x CoO 4 , a compound in which

  6. Probing the effect of neutron excess on the dynamics of Hf compound system

    Science.gov (United States)

    Sharma, Ishita; Kumar, Raj; Sharma, Manoj K.

    2018-05-01

    The reaction dynamics of 170Hf* and 174Hf* compound systems formed in 46,50Ti +124Sn reactions have been analyzed within the framework of Dynamical Cluster-decay Model (DCM) over an energy range of Ec.m.=115-156 MeV. The experimental data of fusion evaporation cross sections for 170,174Hf* systems is successfully addressed by optimizing the value of neck length ΔR. It is to be noted that calculations are performed by taking quadrupole deformations β2 with the optimum orientation of decaying fragments. Here, the effect of neutron excess has been examined on the structural properties of decaying fragments via fragmentation potential and preformation probability. The observation depicts that the isotopic effect prevails at fission region and as we move from lighter nucleus i.e. 170Hf* to heavier nucleus i.e. 174Hf*, the heavy mass fragments (HMF) start contributing along with fission fragments which are equally evident for 170Hf* as well. The ΔR values so obtained are compared at center of mass-energies which consequently provides information regarding the relative time scale of decaying fragments.

  7. Spin excitations in 3D molecular magnets probed by neutron scattering

    CERN Document Server

    Bordallo, H N; Chapon, L C; Manson, J L; Cook, J C; Lee, S H; Copley, J R D; Yildirim, T; Kern, S

    2002-01-01

    The emerging field of molecular magnetism constitutes a new branch of materials science that deals with the magnetic properties of molecules, or assemblies of molecules, that contain magnetic centers. The growing interest in understanding the origin of the magnetic ordering in these materials is to obtain novel multiproperty molecular magnetic materials with high transition temperatures. Molecules based on the dicyanamide ion [N ident to C-N-C ident to N], abbreviated (dca), such as M(dca) sub 2 [M=Mn, Ni], have shown interesting bulk properties that prompted our inelastic neutron scattering (INS) studies. While the Mn sup 2 sup + ion is isotropic because of its L=0 configuration, the isostructural Ni analog has S=1 and demonstrates marked single-ion anisotropy. Mn(dca) sub 2 is a canted antiferromagnet below 16 K, while Ni(dca) sub 2 is a ferromagnet below 21 K. INS has been used to investigate the magnetic excitations in Mn(dca) sub 2 and Ni(dca) sub 2. For Mn(dca) sub 2 , a Heisenberg model gives good corr...

  8. Probing surface charge potentials of clay basal planes and edges by direct force measurements.

    Science.gov (United States)

    Zhao, Hongying; Bhattacharjee, Subir; Chow, Ross; Wallace, Dean; Masliyah, Jacob H; Xu, Zhenghe

    2008-11-18

    The dispersion and gelation of clay suspensions have major impact on a number of industries, such as ceramic and composite materials processing, paper making, cement production, and consumer product formulation. To fundamentally understand controlling mechanisms of clay dispersion and gelation, it is necessary to study anisotropic surface charge properties and colloidal interactions of clay particles. In this study, a colloidal probe technique was employed to study the interaction forces between a silica probe and clay basal plane/edge surfaces. A muscovite mica was used as a representative of 2:1 phyllosilicate clay minerals. The muscovite basal plane was prepared by cleavage, while the edge surface was obtained by a microtome cutting technique. Direct force measurements demonstrated the anisotropic surface charge properties of the basal plane and edge surface. For the basal plane, the long-range forces were monotonically repulsive within pH 6-10 and the measured forces were pH-independent, thereby confirming that clay basal planes have permanent surface charge from isomorphic substitution of lattice elements. The measured interaction forces were fitted well with the classical DLVO theory. The surface potentials of muscovite basal plane derived from the measured force profiles were in good agreement with those reported in the literature. In the case of edge surfaces, the measured forces were monotonically repulsive at pH 10, decreasing with pH, and changed to be attractive at pH 5.6, strongly suggesting that the charge on the clay edge surfaces is pH-dependent. The measured force profiles could not be reasonably fitted with the classical DLVO theory, even with very small surface potential values, unless the surface roughness was considered. The surface element integration (SEI) method was used to calculate the DLVO forces to account for the surface roughness. The surface potentials of the muscovite edges were derived by fitting the measured force profiles with the

  9. Neutron reflectivity

    Directory of Open Access Journals (Sweden)

    Cousin Fabrice

    2015-01-01

    Full Text Available The specular neutron reflectivity is a technique enabling the measurement of neutron scattering length density profile perpendicular to the plane of a surface or an interface, and thereby the profile of chemical composition. The characteristic sizes that are probed range from around 5 Å up 5000 Å. It is a scattering technique that averages information on the entire surface and it is therefore not possible to obtain information within the plane of the interface. The specific properties of neutrons (possibility of tuning the contrast by isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons makes it particularly interesting in the fields of soft matter, biophysics and magnetic thin films. This course is a basic introduction to the technique and does not address the magnetic reflectivity. It is composed of three parts describing respectively its principle and its formalism, the experimental aspects of the method (spectrometers, samples and two examples related to the materials for energy.

  10. Neutron activation analysis to the profile surface sediments from several sites on the Havana Bay

    International Nuclear Information System (INIS)

    Diaz Riso, O.; Gelen, A.; Lopez, N.; Gonzalez, H.; Manso, M.V.; Graciano, A.M.; Nogueira, C.A.; Beltran, J.; Soto, J.

    2003-01-01

    Instrumental neutron activation analysis (INAA) technique was employed to analyze the surface sediments from several sites on the Havana Bay, Cuba. Measurements of heavy and trace elements in the sediments are reported. The results show that the concentration of the elements is site dependent. The data suggest that an anthropogenic input into the bay from domestic sewage and industries occurred

  11. Surface properties of a nanocrystalline Fe-Ni-Nb-B alloy after neutron irradiation

    International Nuclear Information System (INIS)

    Pavuk, M.; Sitek, J.; Sedlackova, K.

    2014-01-01

    In this work, we studied the impact of a neutron radiation on the surface properties of the nanocrystalline (Fe_0_._2_5Ni_0_._7_5)_8_1Nb_7B_1_2 alloy. Changes in topography and domain structure were observed by means of magnetic force microscopy (MFM). (authors)

  12. Transmission X-ray scattering as a probe for complex liquid-surface structures

    Energy Technology Data Exchange (ETDEWEB)

    Fukuto, Masafumi; Yang, Lin; Nykypanchuk, Dmytro; Kuzmenko, Ivan

    2016-01-28

    The need for functional materials calls for increasing complexity in self-assembly systems. As a result, the ability to probe both local structure and heterogeneities, such as phase-coexistence and domain morphologies, has become increasingly important to controlling self-assembly processes, including those at liquid surfaces. The traditional X-ray scattering methods for liquid surfaces, such as specular reflectivity and grazing-incidence diffraction, are not well suited to spatially resolving lateral heterogeneities due to large illuminated footprint. A possible alternative approach is to use scanning transmission X-ray scattering to simultaneously probe local intermolecular structures and heterogeneous domain morphologies on liquid surfaces. To test the feasibility of this approach, transmission small- and wide-angle X-ray scattering (TSAXS/TWAXS) studies of Langmuir films formed on water meniscus against a vertically immersed hydrophilic Si substrate were recently carried out. First-order diffraction rings were observed in TSAXS patterns from a monolayer of hexagonally packed gold nanoparticles and in TWAXS patterns from a monolayer of fluorinated fatty acids, both as a Langmuir monolayer on water meniscus and as a Langmuir–Blodgett monolayer on the substrate. The patterns taken at multiple spots have been analyzed to extract the shape of the meniscus surface and the ordered-monolayer coverage as a function of spot position. These results, together with continual improvement in the brightness and spot size of X-ray beams available at synchrotron facilities, support the possibility of using scanning-probe TSAXS/TWAXS to characterize heterogeneous structures at liquid surfaces.

  13. Determination of planetary surfaces elemental composition by gamma and neutron spectroscopy

    International Nuclear Information System (INIS)

    Diez, B.

    2009-06-01

    Measuring the neutron and gamma ray fluxes produced by the interaction of galactic cosmic rays with planetary surfaces allow constraining the chemical composition of the upper tens of centimeters of material. Two different angles are proposed to study neutron and gamma spectroscopy: data processing and data interpretation. The present work is in line with two experiments, the Mars Odyssey Neutron Spectrometer (MONS) and the Selene Gamma Ray Spectrometer. A review of the processing operations applied to the MONS dataset is proposed. The resulting dataset is used to determine the depth of the hydrogen deposits below the Martian surface. In water depleted regions, neutron data allow constraining the concentration in elements likely to interact with neutrons. The confrontation of these results to those issued from the Gamma Ray Spectrometer onboard Mars Odyssey provides interesting insight on the geologic context of the Central Elysium Planitia region. These martian questions are followed by the study of the Selene gamma ray data. Although only preliminary processing has been done to date, qualitative lunar maps of major elements (Fe, Ca, Si, Ti, Mg, K, Th, U) have already been realized. (author)

  14. Neutron-induced gamma-ray spectroscopy: simulations for chemical mapping of planetary surfaces

    International Nuclear Information System (INIS)

    Brueckner, J.; Waenke, H.; Reedy, R.C.

    1986-01-01

    Cosmic rays interact with the surface of a planetary body and produce a cascade of secondary particles, such as neutrons. Neutron-induced scattering and capture reactions play an important role in the production of discrete gamma-ray lines that can be measured by a gamma-ray spectrometer on board of an orbiting spacecraft. These data can be used to determine the concentration of many elements in the surface of a planetary body, which provides clues to its bulk composition and in turn to its origin and evolution. To investigate the gamma rays made by neutron interactions, thin targets were irradiated with neutrons having energies from 14 MeV to 0.025 eV. By means of foil activation technique the ratio of epithermal to thermal neutrons was determined to be similar to that in the Moon. Gamma rays emitted by the targets and the surrounding material were detected by a high-resolution germanium detector in the energy range of 0.1 to 8 MeV. Most of the gamma-ray lines that are expected to be used for planetary gamma-ray spectroscopy were found in the recorded spectra and the principal lines in these spectra are presented. 58 refs., 7 figs., 9 tabs

  15. Surface electronic transport measurements: A micro multi-point probe approach

    DEFF Research Database (Denmark)

    Barreto, Lucas

    2014-01-01

    This work is mostly focused on the study of electronic transport properties of two-dimensional materials, in particular graphene and topological insulators. To study these, we have improved a unique micro multi-point probe instrument used to perform transport measurements. Not only the experimental...... quantities are extracted, such as conductivity, carrier density and carrier mobility. • A method to insulate electrically epitaxial graphene grown on metals, based on a stepwise intercalation methodology, is developed and transport measurements are performed in order to test the insulation. • We show...... a direct measurement of the surface electronic transport on a bulk topological insulator. The surface state conductivity and mobility are obtained. Apart from transport properties, we also investigate the atomic structure of the Bi2Se3(111) surface via surface x-ray diraction and low-energy electron...

  16. On the moment of inertia and surface redshift of neutron star

    International Nuclear Information System (INIS)

    Li Wenfei; Zhang Fengshou; Chen Liewen

    2001-01-01

    Using temperature, density and isospin dependent nuclear equation of state, the authors calculated the moment of inertia and surface redshift of neutron star by resolving Tolman-Oppenheimer-Volkoff equation. It is found that the moment of inertia and surface redshift strongly depend on the nuclear equation of state. The equation of state with high value of un-compressibility and symmetry energy strength coefficient provides a big moment of inertia, while effective mass of nucleon has almost no effect on moment of inertia. Meanwhile, the equation of state with high value of un-compressibility and effective mass of nucleon provides a big surface redshift, while the symmetry energy strength coefficient has almost no effect on surface redshift of neutron star. The relationship between moment of inertia and mass is also given. By comparing the calculated results with the one obtained semi-empirically from astronomy, the authors find that a softer equation of state can provide a more reasonable result

  17. Neutron-proton bremsstrahlung from intermediate energy heavy-ion reactions as a probe of the nuclear symmetry energy?

    International Nuclear Information System (INIS)

    Yong, G.-C.; Li Baoan; Chen Liewen

    2008-01-01

    Hard photons from neutron-proton bremsstrahlung in intermediate energy heavy-ion reactions are examined as a potential probe of the nuclear symmetry energy within a transport model. Effects of the symmetry energy on the yields and spectra of hard photons are found to be generally smaller than those due to the currently existing uncertainties of both the in-medium nucleon-nucleon cross sections and the photon production probability in the elementary process pn→pnγ. Very interestingly, nevertheless, the ratio of hard photon spectra R 1/2 (γ) from two reactions using isotopes of the same element is not only approximately independent of these uncertainties but also quite sensitive to the symmetry energy. For the head-on reactions of 132 Sn + 124 Sn and 112 Sn + 112 Sn at E beam /A=50 MeV, for example, the R 1/2 (γ) displays a rise up to 15% when the symmetry energy is reduced by about 20% at ρ=1.3ρ 0 which is the maximum density reached in these reactions

  18. Oxidation of clean silicon surfaces studied by four-point probe surface conductance measurements

    DEFF Research Database (Denmark)

    Petersen, Christian Leth; Grey, Francois; Aono, M.

    1997-01-01

    We have investigated how the conductance of Si(100)-(2 x 1) and Si(111)-(7 x 7) surfaces change during exposure to molecular oxygen. A monotonic decrease in conductance is seen as the (100) surfaces oxidizes. In contract to a prior study, we propose that this change is caused by a decrease in sur...

  19. Probing the surface of aqueous surfactant-perfume mixed solutions during perfume evaporation

    OpenAIRE

    Penfold, J; Thomas, RK; Bradbury, R; Tucker, I; Petkov, JT; Jones, CW; Webster, JRP

    2017-01-01

    The rate of release or evaporation of perfume molecules from surfaces is a key factor in determining the impact of the perfume in a range of applications relating to home and personal care products. For mixtures of the anionic surfactant sodium dodecylsulfate and the model perfume linalool the rate of change of adsorption with time due to forced air flow over a fixed headspace was evaluated using neutron reflectivity over a period of up to ∼250 min. The measurements were made in the limit of ...

  20. Study of plasma-material surface interaction using Langmuir probe technique during plasma treatment

    International Nuclear Information System (INIS)

    Saloum, S.; Akel, M.

    2009-06-01

    In this study, we tried to understand the plasma-surface interactions by using Langmuir probes. Two different types of plasmas were studied, the first is the electropositive plasma in Argon and the second is the electronegative plasma in Sulfur Hexafluoride. In the first type, the effects of Argon gas pressure, the injection of Helium in the remote zone and the substrate bias on the measurements of the Electron Energy Probability Function (EEPF) and on the plasma parameters (electron density (n e ), effective electron temperature (T e ff), plasma potential (V p ) and floating potential (V f )) have been investigated. The obtained EEPFs and plasma parameters have been used to control two remote plasma processes. The first is the remote Plasma Enhanced Chemical Vapor Deposition (PE-CVD) of thin films, on silicon wafers, from Hexamethyldisoloxane (HMDSO) precursor diluted in the remote Ar-He plasma. The second is the pure Argon remote plasma treatment of polymethylmethacrylate (PMMA) polymer surface. In the second type, the plasma diagnostics were performed in the remote zone as a function of SF 6 flow rate, where relative concentrations of fluorine atoms were measured using actinometry optical emission spectroscopy; electron density, electron temperature and plasma potential were determined using single cylindrical Langmuir probe, positive ion flux and negative ion fraction were determined using an planar probe. The silicon etching process in SF 6 plasma was studied. (author)

  1. Study of plasma-material surface interaction using langmuir probe technique during plasma treatment

    International Nuclear Information System (INIS)

    Saloum, S.; Akel, M.

    2012-01-01

    In this study, we tried to understand the plasma-surface interactions by using Langmuir probes. Two different types of plasmas were studied, the first is the electropositive plasma in Argon and the second is the electronegative plasma in Sulfur Hexafluoride. In the first type, the effects of Argon gas pressure, the injection of Helium in the remote zone and the substrate bias on the measurements of the Electron Energy Probability Function (EEPF) and on the plasma parameters (electron density (n e ), effective electron temperature (T e ff), plasma potential (V p ) and floating potential (V f )) have been investigated. The obtained EEPFs and plasma parameters have been used to control two remote plasma processes. The first is the remote Plasma Enhanced Chemical Vapor Deposition (PE-CVD) of thin films, on silicon wafers, from Hexamethyldisiloxane (HMDSO) precursor diluted in the remote Ar-He plasma. The second is the pure Argon remote plasma treatment of polymethylmethacrylate (PMMA) polymer surface. In the second type, the plasma diagnostics were performed in the remote zone as a function of SF 6 flow rate, where relative concentrations of fluorine atoms were measured using actinometry optical emission spectroscopy; electron density, electron temperature and plasma potential were determined using single cylindrical Langmuir probe, positive ion flux and negative ion fraction were determined using an planar probe. The silicon etching process in SF 6 plasma was studied. (author)

  2. A Novel SPM Probe with MOS Transistor and Nano Tip for Surface Electric Properties

    International Nuclear Information System (INIS)

    Lee, Sang H; Lim, Geunbae; Moon, Wonkyu

    2007-01-01

    In this paper, the novel SPM (Scanning Probe Microscope) probe with the planar MOS (Metal-Oxide-Semiconductor) transistor and the FIB (Focused Ion Beam) nano tip is fabricated for the surface electric properties. Since the MOS transistor has high working frequency, the device can overcome the speed limitation of EFM (Electrostatic Force Microscope) system. The sensitivity is also high, and no bulky device such as lock-in-amplifier is required. Moreover, the nano tip with nanometer scale tip radius is fabricated with FIB system, and the resolution can be improved. Therefore, the probe can rapidly detect small localized electric properties with high sensitivity and high resolution. The MOS transistor is fabricated with the common semiconductor process, and the nano tip is grown by the FIB system. The planar structure of the MOS transistor makes the fabrication process easier, which is the advantage on the commercial production. Various electric signals are applied using the function generator, and the measured data represent the well-established electric properties of the device. It shows the promising aspect of the local surface electric property detection with high sensitivity and high resolution

  3. Micro-four-point probes in a UHV scanning electron microscope for in-situ surface-conductivity measurements

    DEFF Research Database (Denmark)

    Shiraki, I.; Nagao, T.; Hasegawa, S.

    2000-01-01

    For in-situ measurements of surface conductivity in ultrahigh vacuum (UHV), we have installed micro-four-point probes (probe spacings down to 4 mum) in a UHV scanning electron microscope (SEM) combined with scanning reflection-high-energy electron diffraction (RHEED). With the aid of piezoactuators...

  4. Improvement to surface lagging systems in a nuclear reactor, particularly of the fast neutron type

    International Nuclear Information System (INIS)

    Lemercier, Guy.

    1979-01-01

    Improvements to surface lagging systems in a nuclear reactor, particularly of the fast neutron kind. This system is composed of an assembly of panels each formed of a stack of metal fabric or trellis held against the surface to be protected, by a double fixing system comprising (a) a tubular component passing through a hole in the panel and applying it against the surface through a bearing plate, and (b) a bolt fitted in the centre of the tubular component, also secured to the surface and holding a washer capable of preventing the fall of the tubular component and the panel should the tubular component fracture [fr

  5. Nanoscale Surface Photovoltage Mapping of 2D Materials and Heterostructures by Illuminated Kelvin Probe Force Microscopy

    KAUST Repository

    Shearer, Melinda J.

    2018-02-01

    Nanomaterials are interesting for a variety of applications, such as optoelectronics and photovoltaics. However, they often have spatial heterogeneity, i.e. composition change or physical change in the topography or structure, which can lead to varying properties that would influence their applications. New techniques must be developed to understand and correlate spatial heterogeneity with changes in electronic properties. Here we highlight the technique of surface photovoltage-Kelvin probe force microscopy (SPV-KFM), which is a modified version of non-contact atomic force microscopy capable of imaging not only the topography and surface potential, but also the surface photovoltage on the nanoscale. We demonstrate its utility in probing monolayer WSe2-MoS2 lateral heterostructures, which form an ultrathin p-n junction promising for photovoltaic and optoelectronic applications. We show surface photovoltage maps highlighting the different photoresponse of the two material regions as a result of the effective charge separation across this junction. Additionally, we study the variations between different heterostructure flakes and emphasize the importance of controlling the synthesis and transfer of these materials to obtain consistent properties and measurements.

  6. Nanoscale Surface Photovoltage Mapping of 2D Materials and Heterostructures by Illuminated Kelvin Probe Force Microscopy

    KAUST Repository

    Shearer, Melinda J.; Li, Ming-yang; Li, Lain-Jong; Jin, Song; Hamers, Robert J

    2018-01-01

    Nanomaterials are interesting for a variety of applications, such as optoelectronics and photovoltaics. However, they often have spatial heterogeneity, i.e. composition change or physical change in the topography or structure, which can lead to varying properties that would influence their applications. New techniques must be developed to understand and correlate spatial heterogeneity with changes in electronic properties. Here we highlight the technique of surface photovoltage-Kelvin probe force microscopy (SPV-KFM), which is a modified version of non-contact atomic force microscopy capable of imaging not only the topography and surface potential, but also the surface photovoltage on the nanoscale. We demonstrate its utility in probing monolayer WSe2-MoS2 lateral heterostructures, which form an ultrathin p-n junction promising for photovoltaic and optoelectronic applications. We show surface photovoltage maps highlighting the different photoresponse of the two material regions as a result of the effective charge separation across this junction. Additionally, we study the variations between different heterostructure flakes and emphasize the importance of controlling the synthesis and transfer of these materials to obtain consistent properties and measurements.

  7. In situ X-ray probing reveals fingerprints of surface platinum oxide.

    Science.gov (United States)

    Friebel, Daniel; Miller, Daniel J; O'Grady, Christopher P; Anniyev, Toyli; Bargar, John; Bergmann, Uwe; Ogasawara, Hirohito; Wikfeldt, Kjartan Thor; Pettersson, Lars G M; Nilsson, Anders

    2011-01-07

    In situ X-ray absorption spectroscopy (XAS) at the Pt L(3) edge is a useful probe for Pt-O interactions at polymer electrolyte membrane fuel cell (PEMFC) cathodes. We show that XAS using the high energy resolution fluorescence detection (HERFD) mode, applied to a well-defined monolayer Pt/Rh(111) sample where the bulk penetrating hard X-rays probe only surface Pt atoms, provides a unique sensitivity to structure and chemical bonding at the Pt-electrolyte interface. Ab initio multiple-scattering calculations using the FEFF code and complementary extended X-ray absorption fine structure (EXAFS) results indicate that the commonly observed large increase of the white-line at high electrochemical potentials on PEMFC cathodes originates from platinum oxide formation, whereas previously proposed chemisorbed oxygen-containing species merely give rise to subtle spectral changes.

  8. The influence of fast neutron irradiation on the noise properties of silicon surface-barrier detectors

    International Nuclear Information System (INIS)

    Dabrowski, W.; Korbel, K.

    1988-01-01

    The susceptibility to the fast neutron irradiation of silicon surface-barrier detectors has been investigated. It was shown that the 1/f-noise decreases substantially with increasing fluence in the range from 10 10 n/cm 2 to 10 11 n/cm 2 . The deterioration of the detector performance is caused mainly by the positively-charged defects induced by the radiation. The critical value of the neutron fluence, at which the detector performance begins to be worsened was also determined. 5 refs., 5 figs. (author)

  9. High quality-factor quartz tuning fork glass probe used in tapping mode atomic force microscopy for surface profile measurement

    Science.gov (United States)

    Chen, Yuan-Liu; Xu, Yanhao; Shimizu, Yuki; Matsukuma, Hiraku; Gao, Wei

    2018-06-01

    This paper presents a high quality-factor (Q-factor) quartz tuning fork (QTF) with a glass probe attached, used in frequency modulation tapping mode atomic force microscopy (AFM) for the surface profile metrology of micro and nanostructures. Unlike conventionally used QTFs, which have tungsten or platinum probes for tapping mode AFM, and suffer from a low Q-factor influenced by the relatively large mass of the probe, the glass probe, which has a lower density, increases the Q-factor of the QTF probe unit allowing it to obtain better measurement sensitivity. In addition, the process of attaching the probe to the QTF with epoxy resin, which is necessary for tapping mode AFM, is also optimized to further improve the Q-factor of the QTF glass probe. The Q-factor of the optimized QTF glass probe unit is demonstrated to be very close to that of a bare QTF without a probe attached. To verify the effectiveness and the advantages of the optimized QTF glass probe unit, the probe unit is integrated into a home-built tapping mode AFM for conducting surface profile measurements of micro and nanostructures. A blazed grating with fine tool marks of 100 nm, a microprism sheet with a vertical amplitude of 25 µm and a Fresnel lens with a steep slope of 90 degrees are used as measurement specimens. From the measurement results, it is demonstrated that the optimized QTF glass probe unit can achieve higher sensitivity as well as better stability than conventional probes in the measurement of micro and nanostructures.

  10. Personal and environmental dosimetry of neutrons in a storage facility and humidity probes soil density; Dosimetria personal y ambiental de neutrones en una instalacion de almacenamiento de sondas de densidad y humedad de suelos

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Fuste, M. J.; Amgarou, K.; Dan Pedro, M. de; Garcia-Orellana, J.; Domingo, C.

    2011-07-01

    The equipment operators are professionally exposed to radiation and the premises where stored are considered controlled areas. Although control of the personal doses of gamma radiation received by the operators during the operation, maintenance and storage of the probes is required and is performed by dosimetry services officially approved, the control of personal and environmental doses due to neutrons generally omitted, since they are small in comparison to the gamma dose.

  11. Use of low energy alkali ion scattering as a probe of surface structure

    International Nuclear Information System (INIS)

    Overbury, S.H.

    1986-01-01

    An overview is given of the use of low energy ion scattering as a probe of surface structure with emphasis on work done using alkali ions. Various schemes for extracting structural information from the ion energy and angle distributions are discussed in terms of advantages and disadvantages of each. The scattering potential which is the primary non-structural parameter needed for analysis, is discussed in terms of recent experimental results. The structure of clean and reconstructed surfaces are discussed, with examples of measurements of layer relaxations on the Mo(111) surface and missing row reconstructions on the Au(110) and Pt(110) surfaces. Studies of adsorbate covered surfaces are presented with respect to location of the adsorbate and its effect on the structure of the underlying substrate. Finally, examples are given which demonstrate the sensitivity of ion scattering to surface defects and disordering on reconstructed Au(110) and Pt(110) surfaces and unreconstructed Mo(111) surfaces, and to ordering of adsorbates on Mo(001). 47 refs., 12 figs

  12. THE INTEGRATED USE OF COMPUTATIONAL CHEMISTRY, SCANNING PROBE MICROSCOPY, AND VIRTUAL REALITY TO PREDICT THE CHEMICAL REACTIVITY OF ENVIRONMENTAL SURFACES

    Science.gov (United States)

    In the last decade three new techniques scanning probe microscopy (SPM), virtual reality (YR) and computational chemistry ave emerged with the combined capability of a priori predicting the chemically reactivity of environmental surfaces. Computational chemistry provides the cap...

  13. Characterizing Surfaces of the Wide Bandgap Semiconductor Ilmenite with Scanning Probe Microcopies

    Science.gov (United States)

    Wilkins, R.; Powell, Kirk St. A.

    1997-01-01

    Ilmenite (FeTiO3) is a wide bandgap semiconductor with an energy gap of about 2.5eV. Initial radiation studies indicate that ilmenite has properties suited for radiation tolerant applications, as well as a variety of other electronic applications. Two scanning probe microscopy methods have been used to characterize the surface of samples taken from Czochralski grown single crystals. The two methods, atomic force microscopy (AFM) and scanning tunneling microscopy (STM), are based on different physical principles and therefore provide different information about the samples. AFM provides a direct, three-dimensional image of the surface of the samples, while STM give a convolution of topographic and electronic properties of the surface. We will discuss the differences between the methods and present preliminary data of each method for ilmenite samples.

  14. Probing the Surface of Platinum during the Hydrogen Evolution Reaction in Alkaline Electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Stoerzinger, Kelsey A. [Physical; Favaro, Marco [Advanced; Joint; Chemical; Ross, Philip N. [Materials; Yano, Junko [Joint; Molecular; Liu, Zhi [State; Division; Hussain, Zahid [Advanced; Crumlin, Ethan J. [Advanced; Joint Center

    2017-11-02

    Understanding the surface chemistry of electrocatalysts in operando can bring insight into the reaction mechanism, and ultimately the design of more efficient materials for sustainable energy storage and conversion. Recent progress in synchrotron based X-ray spectroscopies for in operando characterization allows us to probe the solid/liquid interface directly while applying an external potential, applied here to the model system of Pt in alkaline electrolyte for the hydrogen evolution reaction (HER). We employ ambient pressure X-ray photoelectron spectroscopy (AP-XPS) to identify the oxidation and reduction of Pt-oxides and hydroxides on the surface as a function of applied potential, and further assess the potential for hydrogen adsorption and absorption (hydride formation) during and after the HER. This new window into the surface chemistry of Pt in alkaline brings insight into the nature of the rate limiting step, the extent of H ad/absorption and it’s persistence at more anodic potentials.

  15. Atomic species recognition on oxide surfaces using low temperature scanning probe microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zong Min, E-mail: mzmncit@163.com [National Key Laboratory for Electronic Measurement Technology, North University of China, Taiyuan, 030051 (China); Key Laboratory of Instrumentation Science & Dynamic Measurement, North University of China, Ministry of Education, Taiyuan, 030051 (China); School of Instrument and Electronics, North University of China, Taiyuan, 030051 (China); Shi, Yun Bo; Mu, Ji Liang; Qu, Zhang; Zhang, Xiao Ming; Qin, Li [National Key Laboratory for Electronic Measurement Technology, North University of China, Taiyuan, 030051 (China); Key Laboratory of Instrumentation Science & Dynamic Measurement, North University of China, Ministry of Education, Taiyuan, 030051 (China); School of Instrument and Electronics, North University of China, Taiyuan, 030051 (China); Liu, Jun, E-mail: liuj@nuc.edu.cn [National Key Laboratory for Electronic Measurement Technology, North University of China, Taiyuan, 030051 (China); Key Laboratory of Instrumentation Science & Dynamic Measurement, North University of China, Ministry of Education, Taiyuan, 030051 (China); School of Instrument and Electronics, North University of China, Taiyuan, 030051 (China)

    2017-02-01

    Highlights: • The coexisted phase of p(2 × 1)and c(6 × 2) on Cu(110)-O surface using AFM under UHV at low temperature. • Two different c(6 × 2) phase depending on the status of the tip apex. • Electronic state of tip seriously effect the resolution and stability of the sample surface. - Abstract: In scanning probe microscopy (SPM), the chemical properties and sharpness of the tips of the cantilever greatly influence the scanning of a sample surface. Variation in the chemical properties of the sharp tip apex can induce transformation of the SPM images. In this research, we explore the relationship between the tip and the structure of a sample surface using dynamic atomic force microscopy (AFM) on a Cu(110)-O surface under ultra-high vacuum (UHV) at low temperature (78 K). We observed two different c(6 × 2) phase types in which super-Cu atoms show as a bright spot when the tip apex is of O atoms and O atoms show as a bright spot when the tip apex is of Cu atoms. We also found that the electronic state of the tip has a serious effect on the resolution and stability of the sample surface, and provide an explanation for these phenomena. This technique can be used to identify atom species on sample surfaces, and represents an important development in the SPM technique.

  16. The orientation effect in the activities of neutronic probes; Efecto de orientacion en las actividades de sondas neutronicas

    Energy Technology Data Exchange (ETDEWEB)

    Vigon, M A

    1956-07-01

    The formulae relating activity and position of a neutron irradiated Indium foil, have been verified experimentally. Measurements with both thin and thick foils for epithermal neutrons and with thick foils for thermal neutrons have been carried out. The experimental results agree qualitatively with the theoretical predictions. (Author)

  17. AFM Colloidal Probe Measurements Implicate Capillary Condensation in Punch-Particle Surface Interactions during Tableting.

    Science.gov (United States)

    Badal Tejedor, Maria; Nordgren, Niklas; Schuleit, Michael; Millqvist-Fureby, Anna; Rutland, Mark W

    2017-11-21

    Adhesion of the powders to the punches is a common issue during tableting. This phenomenon is known as sticking and affects the quality of the manufactured tablets. Defective tablets increase the cost of the manufacturing process. Thus, the ability to predict the tableting performance of the formulation blend before the process is scaled-up is important. The adhesive propensity of the powder to the tableting tools is mostly governed by the surface-surface adhesive interactions. Atomic force microscopy (AFM) colloidal probe is a surface characterization technique that allows the measurement of the adhesive interactions between two materials of interest. In this study, AFM steel colloidal probe measurements were performed on ibuprofen, MCC (microcrystalline cellulose), α-lactose monohydrate, and spray-dried lactose particles as an approach to modeling the punch-particle surface interactions during tableting. The excipients (lactose and MCC) showed constant, small, attractive, and adhesive forces toward the steel surface after a repeated number of contacts. In comparison, ibuprofen displayed a much larger attractive and adhesive interaction increasing over time both in magnitude and in jump-in/jump-out separation distance. The type of interaction acting on the excipient-steel interface can be related to a van der Waals force, which is relatively weak and short-ranged. By contrast, the ibuprofen-steel interaction is described by a capillary force profile. Even though ibuprofen is not highly hydrophilic, the relatively smooth surfaces of the crystals allow "contact flooding" upon contact with the steel probe. Capillary forces increase because of the "harvesting" of moisture-due to the fast condensation kinetics-leaving a residual condensate that contributes to increase the interaction force after each consecutive contact. Local asperity contacts on the more hydrophilic surface of the excipients prevent the flooding of the contact zone, and there is no such adhesive

  18. Probing the surface properties of a polymer glass with macroscopic friction

    International Nuclear Information System (INIS)

    Bureau, Lionel

    2007-01-01

    We show how macroscopic friction can be used as a sensitive probe of chain dynamics at the surface of a glassy polymer. We present experiments in which a smooth poly(methylmethacrylate) (PMMA) solid slides on flat surfaces presenting different densities of pinning sites available for polymer/substrate bond formation. These experiments indicate that: (i) at high pinning level, frictional dissipation occurs through the sudden flips of molecular-sized bistable regions localized in a nm-thick layer of confined chains, which responds to shear as an elasto-plastic solid, and (ii) in situations of weak pinning, dissipation appears to be governed by a process akin to that proposed for rubber friction. This suggests that some 'glass-to-rubber' transition occurs at the polymer surface when its interaction with the substrate goes from strong to weak. The temperature-dependence of friction provides further support for the presence of a nm-thick layer at the polymer surface, which exhibits a rubberlike response in situation of weak interaction with the countersurface. This behavior results from the interplay between viscous flow in this surface layer, and shear induced depinning of adsorbed surface chains. Moreover, a quantitative analysis of the results indicates that the pinning dynamics of polymer chains is controlled by localized β rotational motions at the interface

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

    Science.gov (United States)

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

    2013-01-21

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

  20. Fouling tendency of ash resulting from burning mixtures of biofuels. Part 3. Influence of probe surface temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mischa Theis; Bengt-Johan Skrifvars; Maria Zevenhoven; Mikko Hupa; Honghi Tran [Aabo Akademi Process Chemistry Centre, Aabo (Finland). Combustion and Materials Chemistry

    2006-10-15

    Mixtures of peat with bark and peat with straw were burned in a large lab-scale entrained flow reactor under controlled conditions, and deposits were collected on an air-cooled probe controlled at four to six different probe surface temperatures between 475 and 625{sup o}C. The results show that the probe surface temperature has no effect on the deposition rate when peat is burned. When burning bark, either alone or in mixtures with peat, the deposition rate decreases with increasing probe surface temperature. When burning straw, either alone or in mixtures with peat, the deposition rate increases with increasing probe surface temperature up to 550{sup o}C and remains constant at higher temperatures. The Cl content in the deposits decreases with increasing probe surface temperature, regardless of the mixture composition. In deposits obtained from burning peat-bark mixtures, K appears as K{sub 2}SO{sub 4} when the deposition rate is low and as KCl when the deposition rate is high. In deposits obtained from burning peat-straw mixtures, no clear relationship is found between the deposition rate and the contents of Cl, S and K in the deposits. 21 refs., 6 figs., 2 tabs.

  1. Glucose oxidase probe as a surface-enhanced Raman scattering sensor for glucose.

    Science.gov (United States)

    Qi, Guohua; Wang, Yi; Zhang, Biying; Sun, Dan; Fu, Cuicui; Xu, Weiqing; Xu, Shuping

    2016-10-01

    Glucose oxidase (GOx) possessing a Raman-active chromophore (flavin adenine dinucleotide) is used as a signal reporter for constructing a highly specific "turn off" surface-enhanced Raman scattering (SERS) sensor for glucose. This sensing chip is made by the electrostatic assembly of GOx over silver nanoparticle (Ag NP)-functionalized SERS substrate through a positively charged polyelectrolyte linker under the pH of 6.86. To trace glucose in blood serum, owing to the reduced pH value caused by the production of gluconic acid in the GOx-catalyzed oxidation reaction, the bonding force between GOx and polyelectrolyte weakens, making GOx drop off from the sensing chip. As a result, the SERS intensity of GOx on the chip decreases along with the concentration of glucose. This glucose SERS sensor exhibits excellent selectivity based on the specific GOx/glucose catalysis reaction and high sensitivity to 1.0 μM. The linear sensing range is 2.0-14.0 mM, which also meets the requirement on the working range of the human blood glucose detection. Using GOx as a probe shows superiority over other organic probes because GOx almost has no toxicity to the biological system. This sensing mechanism can be applied for intracellular in vivo SERS monitoring of glucose in the future. Graphical abstract Glucose oxidase is used as a Raman signal reporter for constructing a highly specific glucose surface-enhanced Raman scattering (SERS) sensor.

  2. Determination of Substances Content of Soil Surface Using Fast Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Elin Nuraini; Elisabeth; Sunardi

    2002-01-01

    Determination of substances content of soil surface using neutron activation analysis has been performed. The aim of this research is to determine whether there are any dangerous, hazardous and toxic substances that released from The Research and Development Center for Advanced Technology (RDCAT) as a government institution has possibility in releasing that substances to the environment by surface water, sewage or rain water that give any dangerous the environmental. The fast neutron activation analysis was used to analyze the type and concentration of substances qualitative and quantitatively. The quantitative analysis was performed using relative method. Samples were counted using NaI(TI) detector. The result showed that there are several substances such as Mn-55, Fe-56, P-31, Al-27. Zn,65 and Mg-24. And there are found any hazardous, dangerous and toxic substances in the samples that causing any danger to human and environment. (author)

  3. Probing surface plasmons in individual Ag nanoparticles in the ultra-violet spectral regime.

    Science.gov (United States)

    Chu, Ming-Wen; Sharma, Pradeep; Chang, Ching-Pin; Liou, Sz Chian; Tsai, Kun-Tong; Wang, Juen-Kai; Wang, Yuh-Lin; Chen, Cheng Hsuan

    2009-06-10

    Previous investigations of surface plasmons in Ag largely focused on their excitations in the visible spectral regime. Using scanning transmission electron microscopy with an electron beam of 0.2 nm in conjunction with electron energy-loss spectroscopy, we spectrally and spatially probe the surface plasmons in individual Ag nanoparticles (approximately 30 nm), grown on Si, in the ultra-violet spectral regime. The nanomaterials show respective sharp and broad surface-plasmon resonances at approximately 3.5 eV (approximately 355 nm) and approximately 7.0 eV (approximately 177 nm), and the correlated spectral calculations established their multipolar characteristics. The near-field distributions of the surface plasmons on the nanoparticles were also mapped out, revealing the predominant dipolar nature of the 3.5 eV excitation with obvious near-field enhancements at one end of the nano-object. The unveiled near-field enhancements have potential applications in plasmonics and molecular sensing.

  4. Probing surface plasmons in individual Ag nanoparticles in the ultra-violet spectral regime

    International Nuclear Information System (INIS)

    Chu, M-W; Chang, C-P; Liou, S C; Wang, J-K; Chen, C H; Sharma, Pradeep; Tsai, K-T; Wang, Y-L

    2009-01-01

    Previous investigations of surface plasmons in Ag largely focused on their excitations in the visible spectral regime. Using scanning transmission electron microscopy with an electron beam of 0.2 nm in conjunction with electron energy-loss spectroscopy, we spectrally and spatially probe the surface plasmons in individual Ag nanoparticles (∼30 nm), grown on Si, in the ultra-violet spectral regime. The nanomaterials show respective sharp and broad surface-plasmon resonances at ∼3.5 eV (∼355 nm) and ∼7.0 eV (∼177 nm), and the correlated spectral calculations established their multipolar characteristics. The near-field distributions of the surface plasmons on the nanoparticles were also mapped out, revealing the predominant dipolar nature of the 3.5 eV excitation with obvious near-field enhancements at one end of the nano-object. The unveiled near-field enhancements have potential applications in plasmonics and molecular sensing.

  5. I. Surface properties of neutron-rich nuclei. II. Pion condensation at finite temperature

    International Nuclear Information System (INIS)

    Kolehmainen, K.A.

    1983-01-01

    In part I, the energy density formalism, the Thomas-Fermi approximation, and Skyrme-type interactions were used to describe the energy density of a semi-infinite slab of neturon-rich nuclear matter at zero temperature. The existence of a drip phase at low proton fractions is allowed in addition to the more dense nuclear phase, and various bulk properties of both phases are found when the system is in equilibrium. The usual definition of the surface energy is extended to apply to the case where drip is present. Assuming a Fermi function type density profile, a constrained variational calculation is performed to determine the neutron and proton surface diffuseness parameters, the thickness of the neutron skin, and the surface energy. Results are obtained for proton fractions reanging from 0.5 (symmetric nuclear matter) to zero (pure neutron matter) for most Skyrme-type interactions in common use. The results are in close agreement with the predictions of the droplet model, as well as with the results of more exact calculations in those cases where the more exact results exist (only for symmetric or nearly symmetric matter in most cases). Significantly different asymmetry dependences for different interactions are found. In part II, several simple but increasingly complex models are used to calculate the threshold for charged pion condensation in neutron-rich nuclear matter at finite temperature. Unlike in mean field theory descriptions of pion condensation, the effects of thermal excitations of the pion field are included. The thermal pion excitations have two important effects: first, to modify the phase diagram qualitatively from that predicted by mean field theory, and second, to make the phase transition to a spatially nonuniform condensed state at finite temperature always first, rather than second, order

  6. Probing Pb+Pb collisions at √sNN = 2.76 TeV with spectator neutrons in AMPT model

    International Nuclear Information System (INIS)

    Mohanty, Bedangadas; Bairathi, Vipul; Haque, Md. Rihan; Chatterjee, Sandeep

    2016-01-01

    In high energy heavy-ion collisions a precise knowledge of the initial state is required in order to describe properties of the strongly interacting medium. There is event by event geometric as well as quantum fluctuations in the initial condition of heavy-ion collisions. The standard technique of analyzing heavy-ion collisions in bins of centrality obtained from final state multiplicity averages out the various initial configurations and thus restricts the study to only a limited range of initial conditions. In this work, we propose an additional binning in terms of total spectator neutrons (L+R), which is sum of left (L) and right (R) going spectator neutrons in an event. This offers us a key control parameter to probe events with broader range of initial conditions providing us an opportunity to investigate events with rarer initial conditions which otherwise get masked when analyzed by centrality binning alone

  7. Phase density of neutrons emitted by an atmosphereless planet

    International Nuclear Information System (INIS)

    Goryachev, B.I.; Isakov, A.I.; Lin'kova, N.V.

    1986-01-01

    An approach to calculation of small planet neutron emission characteristics is developed. Using artificial satellites and space probes information on the planet surface may be obtained by analyzing neutron emission being the result of cosmic rays effect. Available calculation methods permit to calculate angular distribution and neutron flux F 0 from planet surface as a function of its surface layer chemical composition. Neutron flux measured by a sattelite and F 0 flux may be connected by a function describing neuton phase density near the planet

  8. Description of a neutron field perturbed by a probe using coupled Monte Carlo and discrete ordinates radiation transport calculations

    International Nuclear Information System (INIS)

    Zazula, J.M.

    1984-01-01

    This work concerns calculation of a neutron response, caused by a neutron field perturbed by materials surrounding the source or the detector. Solution of a problem is obtained using coupling of the Monte Carlo radiation transport computation for the perturbed region and the discrete ordinates transport computation for the unperturbed system. (author). 62 refs

  9. Impurity deposition on surface probes during different operation modes at EXTRAP T1

    International Nuclear Information System (INIS)

    Gudowska, I.; Bergsaker, H.; Hellblom, G.

    1991-01-01

    Surface probes were used in the impurity control program during initial operation of the EXTRAP T1 device. The EXTRAP concept, design and operation characteristics are given elsewhere. The dimensions of the device are R/a=0.5m/0.06m. Four different modes of operation were studied: pure EXTRAP, mixed EXTRAP, RFP and ULQ. Briefly, all four are toroidal plasma discharges, with poloidal magnetic field due to the toroidal plasma current. In the ULQ case, a relatively strong external toroidal magnetic field is applied. In the RFP, and in the mixed mode, an external toroidal field is applied early in the discharge, and the plasma subsequently relaxes into a state with self-generated toroidal field. In the EXTRAP and mixed EXTRAP modes, an additional strong external octupole field is applied, breaking the poloidal symmetry. Throughout the initial period of operation of the device, the plasma performance was largely dominated by impurities, in particular fluorine, which was present due to an accidental contamination of the vessel. Probes have been exposed in wall/liner position, and the objective has been to measure erosion and deposition and try to identify which mechanisms are mainly responsible for impurity production. (author) 5 refs., 2 figs., 1 tab

  10. Surface topography acquisition method for double-sided near-right-angle structured surfaces based on dual-probe wavelength scanning interferometry.

    Science.gov (United States)

    Zhang, Tao; Gao, Feng; Jiang, Xiangqian

    2017-10-02

    This paper proposes an approach to measure double-sided near-right-angle structured surfaces based on dual-probe wavelength scanning interferometry (DPWSI). The principle and mathematical model is discussed and the measurement system is calibrated with a combination of standard step-height samples for both probes vertical calibrations and a specially designed calibration artefact for building up the space coordinate relationship of the dual-probe measurement system. The topography of the specially designed artefact is acquired by combining the measurement results with white light scanning interferometer (WLSI) and scanning electron microscope (SEM) for reference. The relative location of the two probes is then determined with 3D registration algorithm. Experimental validation of the approach is provided and the results show that the method is able to measure double-sided near-right-angle structured surfaces with nanometer vertical resolution and micrometer lateral resolution.

  11. Characterization of duplex stainless steels by TEM [transmission electron microscopy], SANS [small-angle neutron scattering], and APFIM [atom-probe field ion microscopy] techniques

    International Nuclear Information System (INIS)

    Chung, H.M.; Chopra, O.K.

    1987-06-01

    Results are presented of complementary characterization of aged duplex stainless steels by advanced metallographic techniques, including transmission and high-voltage electron microscopies; small-angle neutron scattering; and atom-probe field ion microscopy. On the basis of the characterization, the mechanisms of aging embrittlement have been shown to be associated with the precipitation of Ni- and Si-rich G phase and Cr-rich α' in the ferrite, and M 23 C 6 carbides on the austenite-ferrite phase boundaries. 19 refs., 19 figs., 1 tab

  12. Investigation of surface potentials in reduced graphene oxide flake by Kelvin probe force microscopy

    Science.gov (United States)

    Negishi, Ryota; Takashima, Kai; Kobayashi, Yoshihiro

    2018-06-01

    The surface potential (SP) of reduced graphene oxide (rGO) flakes prepared by thermal treatments of GO under several conditions was analyzed by Kelvin probe force microscopy. The low-crystalline rGO flakes in which a significant amount of oxygen functional groups and structural defects remain have a much lower SP than mechanically exfoliated graphene free from oxygen and defects. On the other hand, the highly crystalline rGO flake after a thermal treatment for the efficient removal of oxygen functional groups and healing of structural defects except for domain boundary shows SP equivalent to that of the mechanically exfoliated graphene. These results indicate that the work function of rGO is sensitively modulated by oxygen functional groups and structural defects remaining after the thermal reduction process, but is not affected significantly by the domain boundary remaining after the healing of structural defects through the thermal treatment at high temperature.

  13. In situ spectroscopic ellipsometry as a surface sensitive tool to probe thin film growth

    International Nuclear Information System (INIS)

    Liu, C.

    1999-01-01

    Sputtered thin film and multilayer x-ray mirrors are made routinely at the Advanced Photon Source (APS) for the APS users. Precise film growth control and characterization are very critical in fabricating high-quality x-ray mirrors. Film thickness calibrations are carried out using in situ and ex situ spectroscopic ellipsometry, interferometry, and x-ray scattering. To better understand the growth and optical properties of different thin film systems, we have carried out a systematic study of sputtered thin films of Au, Rh, Pg Pd, Cu, and Cr, using in situ ellipsometry. Multiple data sets were obtained in situ for each film material with incremental thicknesses and were analyzed with their correlation in mind. We found that in situ spectroscopic ellipsometry as a surface-sensitive tool can also be used to probe the growth and morphology of the thin film system. This application of in situ spectroscopic ellipsometry for metal thin film systems will be discussed

  14. Development of gamma probe for radiation surveys of the bottoms of surface waters

    International Nuclear Information System (INIS)

    Lee, D.R.; Welch, S.J.; St Aubin, M.J.; Dal Bianco, R.

    1992-01-01

    We have developed a practical method for mapping variations in gamma activity and electrical conductivity of submerged sediments. Prototype probes are being constructed and tested. The first prototype was essentially a background survey meter (Jones, 1979) packaged in a 53-cm-long by 5.4-cm-diameter waterproof vehicle. This tubular vehicle was towed by boat in contact with the bottom sediments of lakes and rivers. Originally, this vehicle was designed (and is still frequently used) for locating groundwater and contaminant entry areas in surface waters. By logging geographic position and sediment variables, it has been possible to produce contour maps in areas of interest. Thus it is possible to optimize environmental analysis and avoid the 'hit or miss' approach of traditional bottom-sediment surveys. (author)

  15. Dissipation at the angstrom scale: Probing the surface and interior of an enzyme

    Science.gov (United States)

    Alavi, Zahra; Zocchi, Giovanni

    2018-05-01

    Pursuing a materials science approach to understanding the deformability of enzymes, we introduce measurements of the phase of the mechanical response function within the nanorheology paradigm. Driven conformational motion of the enzyme is dissipative as characterized by the phase measurements. The dissipation originates both from the surface hydration layer and the interior of the molecule, probed by examining the effect of point mutations on the mechanics. We also document changes in the mechanics of the enzyme examined, guanylate kinase, upon binding its four substrates. GMP binding stiffens the molecule, ATP and ADP binding softens it, while there is no clear mechanical signature of GDP binding. A hyperactive two-Gly mutant is found to possibly trade specificity for speed. Global deformations of enzymes are shown to be dependent on both hydration layer and polypeptide chain dynamics.

  16. Spectroellipsometric, AFM and XPS probing of stainless steel surfaces subjected to biological influences

    Science.gov (United States)

    Vinnichenko, M.; Chevolleau, Th; Pham, M. T.; Poperenko, L.; Maitz, M. F.

    2002-11-01

    Surface modification of austenitic stainless steel (SS) 316L after incubation in growing cell cultures and cell-free media as control has been studied. The following treatments were applied: mouse fibrosarcoma cells L929 for 3 and 7 days, polymorphonuclear neutrophils for 3 and 7 days and human osteosarcoma cells SAOS-2 for 7 and 14 days. Cells were enzymatically removed in all cases. The modified surfaces were probed in comparison with untreated ones by means of spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). XPS shows the appearance of the peak of bonded nitrogen at 400.5 eV characteristic for adsorbed proteins on the surface for each type of cells and for the cell-free medium. Migration of Ni in the adsorbed layer is observed in all cases for samples after the cell cultures. The protein layer thickness is ellipsometrically determined to be within 2.5-6.0 nm for all treated samples with parameterization of its optical constants in Cauchy approach. The study showed that for such biological treatments of the SS the protein layer adsorption is the dominating process in the first 2 weeks, which could play a role in the process of corrosion by complex forming properties with metal ions.

  17. Spectroellipsometric, AFM and XPS probing of stainless steel surfaces subjected to biological influences

    International Nuclear Information System (INIS)

    Vinnichenko, M.; Chevolleau, Th.; Pham, M.T.; Poperenko, L.; Maitz, M.F.

    2002-01-01

    Surface modification of austenitic stainless steel (SS) 316L after incubation in growing cell cultures and cell-free media as control has been studied. The following treatments were applied: mouse fibrosarcoma cells L929 for 3 and 7 days, polymorphonuclear neutrophils for 3 and 7 days and human osteosarcoma cells SAOS-2 for 7 and 14 days. Cells were enzymatically removed in all cases. The modified surfaces were probed in comparison with untreated ones by means of spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). XPS shows the appearance of the peak of bonded nitrogen at 400.5 eV characteristic for adsorbed proteins on the surface for each type of cells and for the cell-free medium. Migration of Ni in the adsorbed layer is observed in all cases for samples after the cell cultures. The protein layer thickness is ellipsometrically determined to be within 2.5-6.0 nm for all treated samples with parameterization of its optical constants in Cauchy approach. The study showed that for such biological treatments of the SS the protein layer adsorption is the dominating process in the first 2 weeks, which could play a role in the process of corrosion by complex forming properties with metal ions

  18. Surface-adaptable all-metal micro-four-point probe with unique configuration

    Science.gov (United States)

    Kim, J. K.; Choi, Y. S.; Lee, D. W.

    2015-07-01

    In this paper, we propose a surface-adaptable all-metal micro-four-point probe (μ4PP) with a unique configuration. The μ4PP consists of four independent metallic sub-cantilevers with sharp Cu tips, and an SU-8 body structure to support the sub-cantilevers. The tip height is approximately 15 μm, and the tips are fabricated by anisotropic wet-etching of silicon followed by Cu electroplating. Each metallic cantilever connected to the SU-8 body structure acts as a flexible spring, so that the conducting tip can make gentle, non-destructive contact with fragile surfaces. To enhance the adhesion between the metallic sub-cantilevers and the SU-8 body, mushroom-shaped Cu structures were fabricated using an under-baked and under-exposed photolithography process. Various μ4PPs were designed and fabricated to verify their diverse range of applications, and preliminary experiments were performed using these fabricated μ4PPs. The resultant flexibility and reliability were experimentally confirmed on several samples, such as a polymer cantilever, a graphene flake, and curved metallic surfaces. We also expect that the proposed μ4PP will be suitable for measuring the anisotropic characteristics of crystal materials or the Hall effect in semiconductors.

  19. Epitaxial growth of pentacene on alkali halide surfaces studied by Kelvin probe force microscopy.

    Science.gov (United States)

    Neff, Julia L; Milde, Peter; León, Carmen Pérez; Kundrat, Matthew D; Eng, Lukas M; Jacob, Christoph R; Hoffmann-Vogel, Regina

    2014-04-22

    In the field of molecular electronics, thin films of molecules adsorbed on insulating surfaces are used as the functional building blocks of electronic devices. Control of the structural and electronic properties of the thin films is required for reliably operating devices. Here, noncontact atomic force and Kelvin probe force microscopies have been used to investigate the growth and electrostatic landscape of pentacene on KBr(001) and KCl(001) surfaces. We have found that, together with molecular islands of upright standing pentacene, a new phase of tilted molecules appears near step edges on KBr. Local contact potential differences (LCPD) have been studied with both Kelvin experiments and density functional theory calculations. Our images reveal that differently oriented molecules display different LCPD and that their value is independent of the number of molecular layers. These results point to the formation of an interface dipole, which may be explained by a partial charge transfer from the pentacene to the surface. Moreover, the monitoring of the evolution of the pentacene islands shows that they are strongly affected by dewetting: Multilayers build up at the expense of monolayers, and in the Kelvin images, previously unknown line defects appear, which reveal the epitaxial growth of pentacene crystals.

  20. Efficient optical probes for fast surface velocimetry: multiple frequency issues for Fabry and VISAR methods

    Science.gov (United States)

    Goosman, David R.; Avara, George R.; Perry, Stephen J.

    2001-04-01

    We have in the past used several types of optical probe lenses for delivering and collecting laser light to an experiment for laser velocimetry. When the test surface was in focus, however, the collected light would fill mostly the laser fiber rather than the collection fiber(s). We have designed, developed and used for 8 years nested-lens probe assemblies that solve this problem. Our first version used a commercial AR-coated glass achromat, which we cored to remove the inner fourth of its area. The core was then reinserted with its optical center offset from that of annulus by an amount slightly less than the separation between the laser and collector fibers. The laser and collector fibers are placed in contact with each other behind the lens and have NA values of 0.11 and 0.22, respectively. Because most of the collected light now focused on the collection fiber, this system was far superior to the single lens systems, but was laborious. For the last five years we used injection-molded acrylic aspheric nested lenses, which are inexpensive in quantity and require little labor to install into a probe. Only an azimuthal rotation and positioning of the fiber plane are needed to incorporate the plastic lens into a probe. Special ray-trace codes were written and used to design the lens, and many iterations by the molder were required to develop the injection processing parameters to produce a good lens, since it was thick for its diameter. These probes have real light collection efficiencies of 75% of theoretical, work well over a wide range of distances, with collection depths of field matching theory. The lenses can take 100 watts of pulsed power many times without damage, since the lens is designed so that reflections from the lens surface do not focus within the lens. The collection fiber size is designed to work with our manybeam velocimeter facility reported in a previous Congress, where the collection NA times collection fiber size exceeds the acceptance of the

  1. Probing electronic phase transitions with phonons via inelastic neutron scattering: superconductivity in borocarbides, charge and magnetic order in manganites

    Energy Technology Data Exchange (ETDEWEB)

    Weber, F.

    2007-11-02

    The present thesis concentrates on the signatures of strong electron-phonon coupling in phonon properties measured by inelastic neutron scattering. The inelastic neutron scattering experiments were performed on the triple-axis spectrometers 1T and DAS PUMA at the research reactors in Saclay (France) and Munich (Germany), respectively. The work is subdivided into two separate chapters: In the first part, we report measurements of the lattice dynamical properties, i.e. phonon frequency, linewidth and intensity, of the conventional, i.e. phonon-mediated, superconductor YNi{sub 2}B{sub 2}C of the rare-earth-borocarbide family. The detailed check of theoretical predictions for these properties, which were calculated in the theory group of our institute, was one major goal of this work. We measured phonons in the normal state, i.e. T>T{sub c}, for several high symmetry directions up to 70 meV. We were able to extract the full temperature dependence of the superconducting energy gap 2{delta}(T) from our phonon scans with such accuracy that even deviations from the weak coupling BCS behaviour could be clearly observed. By measuring phonons at different wave vectors we demonstrated that phonons are sensitive to the gap anisotropy under the precondition, that different phonons get their coupling strength from different parts of the Fermi surface. In the second part, we investigated the properties of Mn-O bond-stretching phonons in the bilayer manganite La{sub 2-2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7}. At the doping level x=0.38 this compound has an ferromagnetic groundstate and exhibits the so-called colossal magnetoresistance effect in the vicinity of the Curie temperature T{sub C}. The atomic displacement patterns of the investigated phonons closely resemble possible Jahn-Teller distortions of the MnO{sub 6} octahedra, which are introduced in this compound by the Jahn-Teller active Mn{sup 3+} ions. We observed strong renormalizations of the phonon frequencies and clear peaks of

  2. Probing electronic phase transitions with phonons via inelastic neutron scattering: superconductivity in borocarbides, charge and magnetic order in manganites

    International Nuclear Information System (INIS)

    Weber, F.

    2007-01-01

    The present thesis concentrates on the signatures of strong electron-phonon coupling in phonon properties measured by inelastic neutron scattering. The inelastic neutron scattering experiments were performed on the triple-axis spectrometers 1T and DAS PUMA at the research reactors in Saclay (France) and Munich (Germany), respectively. The work is subdivided into two separate chapters: In the first part, we report measurements of the lattice dynamical properties, i.e. phonon frequency, linewidth and intensity, of the conventional, i.e. phonon-mediated, superconductor YNi 2 B 2 C of the rare-earth-borocarbide family. The detailed check of theoretical predictions for these properties, which were calculated in the theory group of our institute, was one major goal of this work. We measured phonons in the normal state, i.e. T>T c , for several high symmetry directions up to 70 meV. We were able to extract the full temperature dependence of the superconducting energy gap 2Δ(T) from our phonon scans with such accuracy that even deviations from the weak coupling BCS behaviour could be clearly observed. By measuring phonons at different wave vectors we demonstrated that phonons are sensitive to the gap anisotropy under the precondition, that different phonons get their coupling strength from different parts of the Fermi surface. In the second part, we investigated the properties of Mn-O bond-stretching phonons in the bilayer manganite La 2-2x Sr 1+2x Mn 2 O 7 . At the doping level x=0.38 this compound has an ferromagnetic groundstate and exhibits the so-called colossal magnetoresistance effect in the vicinity of the Curie temperature T C . The atomic displacement patterns of the investigated phonons closely resemble possible Jahn-Teller distortions of the MnO 6 octahedra, which are introduced in this compound by the Jahn-Teller active Mn 3+ ions. We observed strong renormalizations of the phonon frequencies and clear peaks of the intrinsic phonon linewidth near the order

  3. Characterization of local hydrophobicity on sapphire (0001) surfaces in aqueous environment by colloidal probe atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Tomoya; Yamazaki, Kenji; Isono, Toshinari; Ogino, Toshio, E-mail: ogino-toshio-rx@ynu.ac.jp

    2017-02-28

    Highlights: • Local hydrophobicity of phase-separated sapphire (0001) surfaces was investigated. • These surfaces are featured by coexistence of hydrophilic and hydrophobic domains. • Each domain was characterized by colloidal probe atomic force microscopy in water. • Both domains can be distinguished by adhesive forces of the probe to the surfaces. • Characterization in aqueous environment is important in bio-applications of sapphire. - Abstract: Sapphire (0001) surfaces exhibit a phase-separation into hydrophobic and hydrophilic domains upon high-temperature annealing, which were previously distinguished by the thickness of adsorbed water layers in air using atomic force microscopy (AFM). To characterize their local surface hydrophobicity in aqueous environment, we used AFM equipped with a colloidal probe and measured the local adhesive force between each sapphire domain and a hydrophilic SiO{sub 2} probe surface, or a hydrophobic polystyrene one. Two data acquisition modes for statistical analyses were used: one is force measurements at different positions of the surface and the other repeated measurement at a fixed position. We found that adhesive force measurements using the polystyrene probe allow us to distinctly separate the hydrophilic and hydrophobic domains. The dispersion in the force measurement data at different positions of the surface is larger than that in the repeated measurements at a fixed position. It indicates that the adhesive force measurement is repeatable although their data dispersion for the measurement positions is relatively large. From these results, we can conclude that the hydrophilic and hydrophobic domains on the sapphire (0001) surfaces are distinguished by a difference in their hydration degrees.

  4. Neutron Scattering

    International Nuclear Information System (INIS)

    Fayer, Michael J.; Gee, Glendon W.

    2005-01-01

    The neutron probe is a standard tool for measuring soil water content. This article provides an overview of the underlying theory, describes the methodology for its calibration and use, discusses example applications, and identifies the safety issues. Soil water makes land-based life possible by satisfying plant water requirements, serving as a medium for nutrient movement to plant roots and nutrient cycling, and controlling the fate and transport of contaminants in the soil environment. Therefore, a successful understanding of the dynamics of plant growth, nutrient cycling, and contaminant behavior in the soil requires knowledge of the soil water content as well as its spatial and temporal variability. After more than 50 years, neutron probes remain the most reliable tool available for field monitoring of soil water content. Neutron probes provide integrated measurements over relatively large volumes of soil and, with proper access, allow for repeated sampling of the subsurface at the same locations. The limitations of neutron probes include costly and time-consuming manual operation, lack of data automation, and costly regulatory requirements. As more non-radioactive systems for soil water monitoring are developed to provide automated profiling capabilities, neutron-probe usage will likely decrease. Until then, neutron probes will continue to be a standard for reliable measurements of field water contents in soils around the globe

  5. Development of Cold Neutron Activation Station at HANARO Cold Neutron Source

    International Nuclear Information System (INIS)

    Sun, G. M.; Hoang, S. M. T.; Moon, J. H.; Chung, Y. S.; Cho, S. J.; Lee, K. H.; Park, B. G.; Choi, H. D.

    2012-01-01

    A new cold neutron source at the HANARO Research Reactor had been constructed in the framework of a five-year project, and ended in 2009. It has seven neutron guides, among which five guides were already allocated for a number of neutron scattering instruments. A new two-year project to develop a Cold Neutron Activation Station (CONAS) was carried out at the two neutron guides since May 2010, which was supported by the program of the Ministry of Education, Science and Technology, Korea. Fig. 1 shows the location of CONAS. CONAS is a complex facility including several radioanalytical instruments utilizing neutron capture reaction to analyze elements in a sample. It was designed to include three instruments like a CN-PGAA (Cold Neutron - Prompt Gamma Activation Analysis), a CN-NIPS (Cold Neutron - Neutron Induced Pair Spectrometer), and a CN-NDP (Cold Neutron - Neutron-induced prompt charged particle Depth Profiling). Fig. 2 shows the conceptual configuration of the CONAS concrete bioshield and the instruments. CN-PGAA and CN-NIPS measure the gamma-rays promptly emitted from the sample after neutron capture, whereas CN-NDP is a probe to measure the charged particles emitted from the sample surface after neutron capture. For this, we constructed two cold neutron guides called CG1 and CG2B guides from the CNS

  6. Estimates of visibility of the surface of Venus from descent probes and balloons

    Science.gov (United States)

    Moroz, V. I.

    2002-03-01

    One of the tasks of future missions to Venus could be imaging of the surface either from a probe during its descent or from a balloon that drifts at a definite height below the main cloud deck. The undercloud atmosphere restricts capabilities of this experiment in three ways: (1) true absorption in bands of CO 2 and H 2O, (2) gaseous Rayleigh scattering, and (3) scattering and absorption by the undercloud haze. The first and second are dominant, at least below 30- 35 km. Wavelength 1.02 μm seems to be the most favorable as the centre of a window for imaging because the true (band) absorption and Rayleigh optical depth are minimal here. It is also important that this wavelength is within the range of silicon CCD spectral sensitivity. Wavelengths 0.85 and 0.65 μm are included in the analysis. A special number (the visibility factor) is introduced for the quantitative estimates of the atmospheric influence on the quality of surface images. Results of Venera 13 and 14 are used as key information about the optical properties of the atmosphere of Venus. Two cases are discussed: (1) imaging during the daytime in all three windows and (2) night imaging in 1 μm window using the thermal emission of the surface. It is shown that at daytime 3-color imaging with the use of all three windows would be difficult from heights more than a few kilometers, but in 1 μm the approximate upper limit is about 15 km. Visibility of highlands will be better. Night conditions are better for imaging: pictures in 1 μm window. Night images may have acceptable quality just after the passage of the lower boundary of the main cloud deck (48- 50 km). However, interpretation may meet difficulties due to mixing effects of temperatures and emissivity surface fields. NIR surface mapping from orbiters is possible, but it will not provide space resolution better than about 50- 100 km. This mapping will deliver information about surface temperature (linked with topography). Constraints on the mineral

  7. Laser spectroscopy of cadmium isotopes: probing the nuclear structure between the neutron 50 and 82 shell closures

    CERN Multimedia

    Blaum, K; Stroke, H H; Krieger, A R

    We propose to study the isotopic chain of cadmium with high-resolution laser spectroscopy for the first time. Our goal is to determine nuclear spins, moments and root-mean-square charge radii of ground and isomeric states between the neutron 50 and 82 shell closures, contributing decisively to a better understanding of the nuclear structure in the vicinity of the doubly-magic $^{100}$Sn and $^{132}$Sn. On the neutron-rich side this is expected to shed light on a shell-quenching hypothesis and consequently on the duration of the r-process along the waiting-point nuclei below $^{130}$Cd. On the neutron-deficient side it may elucidate the role of the cadmium isotopes in the rp-process for rapidly accreting neutron stars.

  8. Large area window on vacuum chamber surface for neutron scattering instruments

    International Nuclear Information System (INIS)

    Itoh, Shinichi; Yokoo, Tetsuya; Ueno, Kenji; Suzuki, Junichi; Teraoku, Takuji; Tsuchiya, Masao

    2012-01-01

    The feasibility of a large area window using a thin aluminum plate on the surface of the vacuum chamber for neutron scattering instruments at a pulsed neutron source was investigated. In the prototype investigation for a window with an area of 1m×1.4m and a thickness of 1 mm, the measured pressure dependence of the displacement agreed well with a calculation using a nonlinear strain–stress curve up to the plastic deformation region. In addition, we confirmed the repetition test up to 2000 pressurization-and-release cycles, which is sufficient for the lifetime of the vacuum chamber for neutron scattering instruments. Based on these investigations, an actual model of the window to be mounted on the vacuum chamber of the High Resolution Chopper Spectrometer (HRC) at J-PARC was designed. By using a calculated stress distribution on the window, the clamping structure capable of balancing the tension in the window was determined. In a model with a structure identical to the actual window, we confirmed the repetition test over more than 7000 pressurization-and-release cycles, which shows a lifetime long enough for the actual usage of the vacuum chamber on the HRC.

  9. Neutron spin echo scattering angle measurement (SESAME)

    International Nuclear Information System (INIS)

    Pynn, R.; Fitzsimmons, M.R.; Fritzsche, H.; Gierlings, M.; Major, J.; Jason, A.

    2005-01-01

    We describe experiments in which the neutron spin echo technique is used to measure neutron scattering angles. We have implemented the technique, dubbed spin echo scattering angle measurement (SESAME), using thin films of Permalloy electrodeposited on silicon wafers as sources of the magnetic fields within which neutron spins precess. With 30-μm-thick films we resolve neutron scattering angles to about 0.02 deg. with neutrons of 4.66 A wavelength. This allows us to probe correlation lengths up to 200 nm in an application to small angle neutron scattering. We also demonstrate that SESAME can be used to separate specular and diffuse neutron reflection from surfaces at grazing incidence. In both of these cases, SESAME can make measurements at higher neutron intensity than is available with conventional methods because the angular resolution achieved is independent of the divergence of the neutron beam. Finally, we discuss the conditions under which SESAME might be used to probe in-plane structure in thin films and show that the method has advantages for incident neutron angles close to the critical angle because multiple scattering is automatically accounted for

  10. Footprint radius of a cosmic-ray neutron probe for measuring soil-water content and its spatiotemporal variability in an alpine meadow ecosystem

    Science.gov (United States)

    Zhu, Xuchao; Cao, Ruixue; Shao, Mingan; Liang, Yin

    2018-03-01

    Cosmic-ray neutron probes (CRNPs) have footprint radii for measuring soil-water content (SWC). The theoretical radius is much larger at high altitude, such as the northern Tibetan Plateau, than the radius at sea level. The most probable practical radius of CRNPs for the northern Tibetan Plateau, however, is not known due to the lack of SWC data in this hostile environment. We calculated the theoretical footprint of the CRNP based on a recent simulation and analyzed the practical radius of a CRNP for the northern Tibetan Plateau by measuring SWC at 113 sampling locations on 21 measuring occasions to a depth of 30 cm in a 33.5 ha plot in an alpine meadow at 4600 m a.s.l. The temporal variability and spatial heterogeneity of SWC within the footprint were then analyzed. The theoretical footprint radius was between 360 and 420 m after accounting for the influences of air humidity, soil moisture, vegetation and air pressure. A comparison of SWCs measured by the CRNP and a neutron probe from access tubes in circles with different radii conservatively indicated that the most probable experimental footprint radius was >200 m. SWC within the CRNP footprint was moderately variable over both time and space, but the temporal variability was higher. Spatial heterogeneity was weak, but should be considered in future CRNP calibrations. This study provided theoretical and practical bases for the application and promotion of CRNPs in alpine meadows on the Tibetan Plateau.

  11. Bilinear magnetoelectric resistance as a probe of three-dimensional spin texture in topological surface states

    Science.gov (United States)

    He, Pan; Zhang, Steven S.-L.; Zhu, Dapeng; Liu, Yang; Wang, Yi; Yu, Jiawei; Vignale, Giovanni; Yang, Hyunsoo

    2018-05-01

    Surface states of three-dimensional topological insulators exhibit the phenomenon of spin-momentum locking, whereby the orientation of an electron spin is determined by its momentum. Probing the spin texture of these states is of critical importance for the realization of topological insulator devices, but the main technique currently available is spin- and angle-resolved photoemission spectroscopy. Here we reveal a close link between the spin texture and a new kind of magnetoresistance, which depends on the relative orientation of the current with respect to the magnetic field as well as the crystallographic axes, and scales linearly with both the applied electric and magnetic fields. This bilinear magnetoelectric resistance can be used to map the spin texture of topological surface states by simple transport measurements. For a prototypical Bi2Se3 single layer, we can map both the in-plane and out-of-plane components of the spin texture (the latter arising from hexagonal warping). Theoretical calculations suggest that the bilinear magnetoelectric resistance originates from conversion of a non-equilibrium spin current into a charge current under application of the external magnetic field.

  12. An Inelastic Neutron Scattering Study of Confined Surface Water on Rutile Nanoparticles

    International Nuclear Information System (INIS)

    Spencer, Elinor; Levchenko, Andrey; Ross, Nancy; Kolesnikov, Alexander I.; Boerio-Goates, Juliana; Woodfield, Brian; Navrotsky, Alexandra; Li, Guangshe

    2009-01-01

    The vibrational density of states (VDOS) for water confined on the surface of rutile-TiO2 nanoparticles has been extracted from low temperature inelastic neutron scattering spectra. Two rutile-TiO2 nanoparticle samples that differ in their respective levels of hydration, namely TiO2 0.37H2O (1) and TiO2 0.22H2O (2) have been studied. The temperature dependency of the heat capacities for the two samples has been quantified from the VDOS. The results from this study are compared with previously reported data for water confined on anatase-TiO2 nanoparticles.

  13. Hydraulic conductivity obtained by instantaneous profile method using retention curve and neutron probes and Genuchten model; Condutividade hidraulica obtida pelo metodo do perfil instantaneo utilizando curva de retencao e sonda de neutrons e pelo modelo de Genuchten

    Energy Technology Data Exchange (ETDEWEB)

    Berretta, Ana Lucia Olmedo

    1999-07-01

    The hydraulic conductivity is one of the most important parameters to understand the movement of water in the unsaturated zone. Reliable estimations are difficult to obtain, once the hydraulic conductivity is highly variable. This study was carried out at 'Escola Superior de Agricultura Luiz de Queiroz', Universidade de Sao Paulo, in a Kandiudalfic Eutrudox soil. The hydraulic conductivity was determined by a direct and an indirect method. The instantaneous profile method was described and the hydraulic conductivity as a function of soil water content was determined by solving the Richards equation. Tensiometers were used to estimate the total soil water potential, and the neutron probe and the soil retention curve were used to estimate soil water content in the direct method. The neutron probe showed to be not adequately sensible to the changes of soil water content in this soil. Despite of the soil retention curve provides best correlation values to soil water content as a function of water redistribution time, the soil water content in this soil did not vary too much till the depth of 50 cm, reflecting the influence of the presence of a Bt horizon. The soil retention curve was well fitted by the van Genuchten model used as an indirect method. The values of the van Genuchten and the experimental relative hydraulic conductivity obtained by the instantaneous profile method provided a good correlation. However, the values estimated by the model were always lower than that ones obtained experimentally. (author)

  14. Influence of Surface Adsorption on Work Function Measurements on Gold-Platinum Interface Using Scanning Kelvin Probe Microscopy

    International Nuclear Information System (INIS)

    Mugo, Simon; Yuan Jun

    2012-01-01

    Surface potential difference (SPD) on freshly coated gold and platinum electrodes have been found to be much smaller than bulk work functions consideration and to be dependent on time. We show these discrepancies arise due to formation of surface dipoles caused by adsorbed contaminants in ambient environments. The process is reversible by gentle annealing consistent with contaminant hypothesis. Examination of potential changes on individual electrodes suggest that the Pt surface is more sensitive to ambient conditions than the Au surface in accordance with their relative chemical activities. The result has great implication for interpretation of Kelvin probe measurements obtained on practical devices exposed to ambient environments.

  15. MAGNETIC NEUTRON SCATTERING

    Energy Technology Data Exchange (ETDEWEB)

    ZALIZNYAK,I.A.; LEE,S.H.

    2004-07-30

    Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern

  16. Direct Surface and Droplet Microsampling for Electrospray Ionization Mass Spectrometry Analysis with an Integrated Dual-Probe Microfluidic Chip

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Cong-Min [Institute of Microanalytical; Zhu, Ying [Institute of Microanalytical; Jin, Di-Qiong [Institute of Microanalytical; Kelly, Ryan T. [Environmental; Fang, Qun [Institute of Microanalytical

    2017-08-15

    Ambient mass spectrometry (MS) has revolutionized the way of MS analysis and broadened its application in various fields. This paper describes the use of microfluidic techniques to simplify the setup and improve the functions of ambient MS by integrating the sampling probe, electrospray emitter probe, and online mixer on a single glass microchip. Two types of sampling probes, including a parallel-channel probe and a U-shaped channel probe, were designed for dryspot and liquid-phase droplet samples, respectively. We demonstrated that the microfabrication techniques not only enhanced the capability of ambient MS methods in analysis of dry-spot samples on various surfaces, but also enabled new applications in the analysis of nanoliter-scale chemical reactions in an array of droplets. The versatility of the microchip-based ambient MS method was demonstrated in multiple different applications including evaluation of residual pesticide on fruit surfaces, sensitive analysis of low-ionizable analytes using postsampling derivatization, and high-throughput screening of Ugi-type multicomponent reactions.

  17. Measurement of integrated coefficients of ultracold neutron reflection from solid surfaces

    International Nuclear Information System (INIS)

    Golikov, V.V.; Kulagin, E.N.; Nikitenko, Yu.V.

    1985-01-01

    The method of measurement of the integrated coefficients of ultracold neutrons (UCN) reflection from solid surfaces is reported. A simple formula is suggested which expresses the integrated coefficients of UCN reflection from a given sample through the measured counting rate of the detector with and without strong absorber (polyethelene). The parameters are determined describing anisotropic and inhomogeneity properties of UCN reflection from Al, Mg, Pb, Zn, Mo, stainless steel, T and V are measured. The thickness of oxide layers is determined within the 5-10A accuracy limits from the experimental coefficients of UCN reflection from metals having on their surfaces the oxides with boundary velocity larger than that for the metal. It has been determined that the density of 5000 A layer of heavy ice freezed on aluminium is 0.83 +- 0.05 from the crystal ice density

  18. Direct protein quantification in complex sample solutions by surface-engineered nanorod probes

    KAUST Repository

    Schrittwieser, Stefan

    2017-06-30

    Detecting biomarkers from complex sample solutions is the key objective of molecular diagnostics. Being able to do so in a simple approach that does not require laborious sample preparation, sophisticated equipment and trained staff is vital for point-of-care applications. Here, we report on the specific detection of the breast cancer biomarker sHER2 directly from serum and saliva samples by a nanorod-based homogeneous biosensing approach, which is easy to operate as it only requires mixing of the samples with the nanorod probes. By careful nanorod surface engineering and homogeneous assay design, we demonstrate that the formation of a protein corona around the nanoparticles does not limit the applicability of our detection method, but on the contrary enables us to conduct in-situ reference measurements, thus further strengthening the point-of-care applicability of our method. Making use of sandwich assays on top of the nanorods, we obtain a limit of detection of 110 pM and 470 pM in 10-fold diluted spiked saliva and serum samples, respectively. In conclusion, our results open up numerous applications in direct protein biomarker quantification, specifically in point-of-care settings where resources are limited and ease-of-use is of essence.

  19. Direct protein quantification in complex sample solutions by surface-engineered nanorod probes

    KAUST Repository

    Schrittwieser, Stefan; Pelaz, Beatriz; Parak, Wolfgang J.; Lentijo Mozo, Sergio; Soulantica, Katerina; Dieckhoff, Jan; Ludwig, Frank; Schotter, Joerg

    2017-01-01

    Detecting biomarkers from complex sample solutions is the key objective of molecular diagnostics. Being able to do so in a simple approach that does not require laborious sample preparation, sophisticated equipment and trained staff is vital for point-of-care applications. Here, we report on the specific detection of the breast cancer biomarker sHER2 directly from serum and saliva samples by a nanorod-based homogeneous biosensing approach, which is easy to operate as it only requires mixing of the samples with the nanorod probes. By careful nanorod surface engineering and homogeneous assay design, we demonstrate that the formation of a protein corona around the nanoparticles does not limit the applicability of our detection method, but on the contrary enables us to conduct in-situ reference measurements, thus further strengthening the point-of-care applicability of our method. Making use of sandwich assays on top of the nanorods, we obtain a limit of detection of 110 pM and 470 pM in 10-fold diluted spiked saliva and serum samples, respectively. In conclusion, our results open up numerous applications in direct protein biomarker quantification, specifically in point-of-care settings where resources are limited and ease-of-use is of essence.

  20. Probing Nitrosyl Ligation of Surface-Confined Metalloporphyrins by Inelastic Electron Tunneling Spectroscopy

    Science.gov (United States)

    2013-01-01

    Complexes obtained by the ligation of nitric oxide (NO) to metalloporphyrins represent important model systems with biological relevance. Herein we report a molecular-level investigation of surface-confined cobalt tetraphenyl porphyrin (Co-TPP) species and their interaction with NO under ultrahigh vacuum conditions. It is demonstrated that individual NO adducts can be desorbed using the atomically sharp tip of a scanning tunneling microscope, whereby a writing process is implemented for fully saturated regular metalloporphyrin arrays. The low-energy vibrational characteristics of individual Co-TPP-nitrosyl complexes probed by inelastic electron tunneling spectroscopy (IETS) reveal a prominent signature at an energy of ≃31 meV. Using density functional theory-based IETS simulations—the first to be performed on such an extensive interfacial nanosystem—we succeed to reproduce the low-frequency spectrum for the NO-ligated complex and explain the absence of IETS activity for bare Co-TPP. Moreover, we can conclusively assign the IETS peak of NO-Co-TPP to a unique vibration mode involving the NO complexation site, namely, the in-plane Co–N–O rocking mode. In addition, we verify that the propensity rules previously designed on small aromatic systems and molecular fragments hold true for a metal–organic entity. This work notably permits one to envisage IETS spectroscopy as a sensitive tool to chemically characterize hybrid interfaces formed by complex metal–organic units and gaseous adducts. PMID:23718257

  1. Ultrafast relaxation dynamics of a biologically relevant probe dansyl at the micellar surface.

    Science.gov (United States)

    Sarkar, Rupa; Ghosh, Manoranjan; Pal, Samir Kumar

    2005-02-01

    We report picosecond-resolved measurement of the fluorescence of a well-known biologically relevant probe, dansyl chromophore at the surface of a cationic micelle (cetyltrimethylammonium bromide, CTAB). The dansyl chromophore has environmentally sensitive fluorescence quantum yields and emission maxima, along with large Stokes shift. In order to study the solvation dynamics of the micellar environment, we measured the fluorescence of dansyl chromophore attached to the micellar surface. The fluorescence transients were observed to decay (with time constant approximately 350 ps) in the blue end and rise with similar timescale in the red end, indicative of solvation dynamics of the environment. The solvation correlation function is measured to decay with time constant 338 ps, which is much slower than that of ordinary bulk water. Time-resolved anisotropy of the dansyl chromophore shows a bi-exponential decay with time constants 413 ps (23%) and 1.3 ns (77%), which is considerably slower than that in free solvents revealing the rigidity of the dansyl-micelle complex. Time-resolved area-normalized emission spectroscopic (TRANES) analysis of the time dependent emission spectra of the dansyl chromophore in the micellar environment shows an isoemissive point at 21066 cm-1. This indicates the fluorescence of the chromophore contains emission from two kinds of excited states namely locally excited state (prior to charge transfer) and charge transfer state. The nature of the solvation dynamics in the micellar environments is therefore explored from the time-resolved anisotropy measurement coupled with the TRANES analysis of the fluorescence transients. The time scale of the solvation is important for the mechanism of molecular recognition.

  2. Probing protein surface with a solvent mimetic carbene coupled to detection by mass spectrometry.

    Science.gov (United States)

    Gómez, Gabriela E; Mundo, Mariana R; Craig, Patricio O; Delfino, José M

    2012-01-01

    Much knowledge into protein folding, ligand binding, and complex formation can be derived from the examination of the nature and size of the accessible surface area (SASA) of the polypeptide chain, a key parameter in protein science not directly measurable in an experimental fashion. To this end, an ideal chemical approach should aim at exerting solvent mimicry and achieving minimal selectivity to probe the protein surface regardless of its chemical nature. The choice of the photoreagent diazirine to fulfill these goals arises from its size comparable to water and from being a convenient source of the extremely reactive methylene carbene (:CH(2)). The ensuing methylation depends primarily on the solvent accessibility of the polypeptide chain, turning it into a valuable signal to address experimentally the measurement of SASA in proteins. The superb sensitivity and high resolution of modern mass spectrometry techniques allows us to derive a quantitative signal proportional to the extent of modification (EM) of the sample. Thus, diazirine labeling coupled to electrospray mass spectrometry (ESI-MS) detection can shed light on conformational features of the native as well as non-native states, not easily addressable by other methods. Enzymatic fragmentation of the polypeptide chain at the level of small peptides allows us to locate the covalent tag along the amino acid sequence, therefore enabling the construction of a map of solvent accessibility. Moreover, by subsequent MS/MS analysis of peptides, we demonstrate here the feasibility of attaining amino acid resolution in defining the target sites. © American Society for Mass Spectrometry, 2011

  3. Surface Photochemistry: Benzophenone as a Probe for the Study of Modified Cellulose Fibres

    Directory of Open Access Journals (Sweden)

    L. F. Vieira Ferreira

    2007-01-01

    Full Text Available This work reports the use of benzophenone, a very well characterized probe, to study new hosts (i.e., modified celluloses grafted with alkyl chains bearing 12 carbon atoms by surface esterification. Laser-induced room temperature luminescence of air-equilibrated or argon-purged solid powdered samples of benzophenone adsorbed onto the two modified celluloses, which will be named C12-1500 and C12-1700, revealed the existence of a vibrationally structured phosphorescence emission of benzophenone in the case where ethanol was used for sample preparation, while a nonstructured emission of benzophenone exists when water was used instead of ethanol. The decay times of the benzophenone emission vary greatly with the solvent used for sample preparation and do not change with the alkylation degree in the range of 1500–1700 micromoles of alkyl chains per gram of cellulose. When water was used as a solvent for sample preparation, the shortest lifetime for the benzophenone emission was observed; this result is similar to the case of benzophenone adsorbed onto the “normal” microcrystalline cellulose surface, with this latter case previously reported by Vieira Ferreira et al. in 1995. This is due to the more efficient hydrogen abstraction reaction from the glycoside rings of cellulose when compared with hydrogen abstraction from the alkyl chains of the modified celluloses. Triplet-triplet transient absorption of benzophenone was obtained in both cases and is the predominant absorption immediately after laser pulse, while benzophenone ketyl radical formation occurs in a microsecond time scale both for normal and modified celluloses.

  4. Probing the neutron star interior and the Equation of State of cold dense matter with the SKA

    NARCIS (Netherlands)

    Watts, A.; Xu, R.; Espinoza, C.; Andersson, N.; Antoniadis, J.; Antonopoulou, D.; Buchner, S.; Dai, S.; Demorest, P.; Freire, P.; Hessels, J.; Margueron, J.; Oertel, M.; Patruno, A.; Possenti, A.; Ransom, S.; Stairs, I.; Stappers, B.

    2015-01-01

    With an average density higher than the nuclear density, neutron stars (NS) provide a unique testground for nuclear physics, quantum chromodynamics (QCD), and nuclear superfluidity. Determination of the fundamental interactions that govern matter under such extreme conditions is one of the major

  5. A study of Venus surface elemental composition from 14 MeV neutron induced gamma ray spectroscopy: Activation analysis

    International Nuclear Information System (INIS)

    Jun, I.; Kim, W.; Smith, M.; Mitrofanov, I.; Litvak, M.

    2011-01-01

    The surface elemental composition of Venus can be determined using an artificially pulsed 14 MeV neutron generator (PNG) combined with a gamma ray spectrometer (GRS). The 14 MeV neutrons will interact with the surface materials and generate gamma rays, characteristic of specific elements, whose energy spectrum will be measured by GRS. These characteristic gamma rays are produced mainly through 3 different neutron interaction mechanisms: capture, inelastic, and activation reactions. Each reaction type has a different neutron energy dependency and different time scale for gamma ray production and transport. Certain elements are more easily identified through one reaction type over the others. Thus, careful analysis of the gamma ray spectra during and after the neutron pulse provides a comprehensive understanding of the surface elemental composition. In this paper, we use a well-tested neutron/gamma transport code, called Monte Carlo N-Particles (MCNP), to investigate the measurement capability of a PNG-GRS detection system through the neutron activation reactions. An activation analysis was performed for a representative soil composition of Venus with a notional operational scenario of PNG and GRS. The analysis shows that the proposed instrument concept can identify most of the modeled surface elements at Venus with sufficient accuracy through the activation mode. Specifically, U, Th, K, Si can be measured to within 1%, Fe within 2%, Al within 10%, Ca within 5%, Mg with 15%, Mn with 20%, and Cl within 6%. Although modeled in the analysis, it is shown that the activation mode alone cannot distinguish the S and Ti peaks.

  6. Circular mode: a new scanning probe microscopy method for investigating surface properties at constant and continuous scanning velocities.

    Science.gov (United States)

    Nasrallah, Hussein; Mazeran, Pierre-Emmanuel; Noël, Olivier

    2011-11-01

    In this paper, we introduce a novel scanning probe microscopy mode, called the circular mode, which offers expanded capabilities for surface investigations especially for measuring physical properties that require high scanning velocities and/or continuous displacement with no rest periods. To achieve these specific conditions, we have implemented a circular horizontal displacement of the probe relative to the sample plane. Thus the relative probe displacement follows a circular path rather than the conventional back and forth linear one. The circular mode offers advantages such as high and constant scanning velocities, the possibility to be combined with other classical operating modes, and a simpler calibration method of the actuators generating the relative displacement. As application examples of this mode, we report its ability to (1) investigate the influence of scanning velocity on adhesion forces, (2) measure easily and instantly the friction coefficient, and (3) generate wear tracks very rapidly for tribological investigations. © 2011 American Institute of Physics

  7. Investigation of benzene and toluene layers on 0001 surface of graphite by means of neutron scattering

    International Nuclear Information System (INIS)

    Monkenbusch, M.

    1981-01-01

    The structures of benzene (C 6 H 6 , C 6 D 6 ) and toluene (C 6 H 5 -CH 3 , C 6 D 5 -CD 3 ) monolayers on the basal planes of graphite have been investigated by neutron diffraction. The dynamics of the benzene layer has been studied by observing the incoherently, inelastically scattered neutrons using the time-of-flight method. The main results are: Above a phase transition temperature Tsub(c)approx.=145 K benzene on the basal planes of graphite forms a quasi 2D-fluid with high compressibility. For toluene a fluid phase exists above 140 K, between 70 K and 140 K it forms an incommensurate layer and below 70 K a 3x3 structure has been observed. The fluid phase of adsorbed benzene shows a broad quasielastic scattering indicating an effective surface diffusion coefficient of 10 -4 cm 2 /s at 200 K. The inelastic spectrum has been compared with an appropriate lattice dynamical model. The comparison with the data reveals, can be considered as a fairly anharmonic 2D-solid with a static external potential due to the substrate. (orig./HK)

  8. Improved analytical formulas for x-ray and neutron reflection from surface films

    International Nuclear Information System (INIS)

    Zhou, X.; Chen, S.; Felcher, G.P.

    1992-01-01

    A general and exact expression for x-ray and neutron reflectance and transmittance is given in terms of an integral of the real-space scattering-length-density profile fluctuation of the film, with respect to an arbitrary constant reference density level, over the wave function inside the film. Various special cases and approximations are then derived from this exact form by suitable approximations of the wave function. In particular, two practical approximate formulas are derived which are improvement over the corresponding distorted-wave Born approximations. One is for an arbitrary film deposited on a known substrate and the other for a free liquid surface. Numerical results are used to illustrate the accuracy of these formulas

  9. Probing the properties of the pulsar wind via studying the dispersive effects in the pulses from the pulsar companion in a double neutron-star binary system

    Science.gov (United States)

    Yi, Shu-Xu; Cheng, K.-S.

    2017-12-01

    The velocity and density distribution of e± in the pulsar wind are crucial distinction among magnetosphere models, and contain key parameters determining the high-energy emission of pulsar binaries. In this work, a direct method is proposed, which might probe the properties of the wind from one pulsar in a double-pulsar binary. When the radio signals from the first-formed pulsar travel through the relativistic e± flow in the pulsar wind from the younger companion, the components of different radio frequencies will be dispersed. It will introduce an additional frequency-dependent time-of-arrival delay of pulses, which is function of the orbital phase. In this paper, we formulate the above-mentioned dispersive delay with the properties of the pulsar wind. As examples, we apply the formula to the double-pulsar system PSR J0737-3039A/B and the pulsar-neutron star binary PSR B1913+16. For PSR J0737-3039A/B, the time delay in 300 MHz is ≲ 10 μ s-1 near the superior conjunction, under the optimal pulsar wind parameters, which is approximately half of the current timing accuracy. For PSR B1913+16, with the assumption that the neutron-star companion has a typical spin-down luminosity of 1033 erg s-1, the time delay is as large as 10 - 20 μ s-1 in 300 MHz. The best timing precision of this pulsar is ∼ 5 μ s-1 in 1400 MHz. Therefore, it is possible that we can find this signal in archival data. Otherwise, we can set an upper limit on the spin-down luminosity. Similar analysis can be applied to other 11 known pulsar-neutron star binaries.

  10. Global Distribution of Shallow Water on Mars: Neutron Mapping of Summer-Time Surface by HEND/Odyssey

    Science.gov (United States)

    Mitrofanov, I. G.; Litvak, M. L.; Kozyrev, A. S.; Sanin, A. B.; Tretyakov, V. I.; Boynton, W.; Hamara, D.; Shinohara, C.; Saunders, R. S.; Drake, D.

    2003-01-01

    Orbital mapping of induced neutrons and gamma-rays by Odyssey has recently successfully proven the applicability of nuclear methods for studying of the elementary composition of Martian upper-most subsurface. In particular, the suite of Gamma-Ray Spectrometer (GRS) has discovered the presence of large water-ice rich regions southward and northward on Mars. The data of neutron mapping of summer-time surface are presented below from the Russian High Energy Neutron Spectrometer (HEND), which is a part of GRS suite. These maps represent the content of water in the soil for summer season at Southern and Northern hemispheres, when the winter deposit of CO2 is absent on the surface. The seasonal evolution of CO2 coverage on Mars is the subject of the complementary paper.

  11. Neutron reflectivity study of substrate surface chemistry effects on supported phospholipid bilayer formation on (1120) sapphire.

    Energy Technology Data Exchange (ETDEWEB)

    Oleson, Timothy A. [University of Wisconsin, Madison; Sahai, Nita [University of Akron; Wesolowski, David J [ORNL; Dura, Joseph A [ORNL; Majkrzak, Charles F [ORNL; Giuffre, Anthony J. [University of Wisconsin, Madison

    2012-01-01

    Oxide-supported phospholipid bilayers (SPBs) used as biomimetric membranes are significant for a broad range of applications including improvement of biomedical devices and biosensors, and in understanding biomineralization processes and the possible role of mineral surfaces in the evolution of pre-biotic membranes. Continuous-coverage and/or stacjed SPBs retain properties (e.,g. fluidity) more similar to native biological membranes, which is desirable for most applications. Using neutron reflectivity, we examined face coverage and potential stacking of dipalmitoylphosphatidylcholine (DPPC) bilayers on the (1120) face of sapphire (a-Al2O3). Nearly full bilayers were formed at low to neutral pH, when the sapphire surface is positively charged, and at low ionic strength (l=15 mM NaCl). Coverage decreased at higher pH, close to the isoelectric point of sapphire, and also at high I>210mM, or with addition of 2mM Ca2+. The latter two effects are additive, suggesting that Ca2+ mitigates the effect of higher I. These trends agree with previous results for phospholipid adsorption on a-Al2O3 particles determined by adsorption isotherms and on single-crystal (1010) sapphire by atomic force microscopy, suggesting consistency of oxide surface chemistry-dependent effects across experimental techniques.

  12. Neutron scattering study of the freezing of water near a cupric oxide surface

    Science.gov (United States)

    Torres, J.; Buck, Z. N.; Zhang, F. Z.; Chen, T.; Winholtz, R. A.; Kaiser, H.; Ma, H. B.; Taub, H.; Tyagi, M.

    Oscillating heat pipes (OHP) offer promising two-phase heat transfer for a variety of applications, including cooling of electronic devices.2 Recently, it has been shown that a hydrophilic CuO coating on either the evaporator or condenser sections of a flat-plate OHP can significantly enhance its thermal performance.3 This finding has motivated us to assess the strength of the CuO/H2O interaction by investigating the freezing behavior of H2O in proximity to a CuO surface. Using the High-Flux Backscattering Spectrometer at NIST, we have measured the intensity of neutrons scattered elastically from a well-hydrated sample of CuO-coated Cu foils that mimic the oxide surfaces in a flat-plate OHP. We observe abrupt freezing of bulk-like H2O above the CuO surface at 270 K followed by continuous freezing of the interfacial H2O down to 265 K. This freezing behavior is qualitatively similar to that found for water near a zwitterionic single-supported bilayer lipid membrane.3 Further studies are planned to compare the diffusion coefficients of the interfacial water for the coated and uncoated OHPs.22F.Z. Zhang et al., submitted to J. Heat Transfer. 3M. Bai et al., Europhys. Lett. 98, 48006 (2012); Miskowiec et al., Europhys. Lett. 107, 28008 (2014). Supported by NSF Grant Nos. DMR-0944772 and DGE-1069091.

  13. Application of the rigorous method to x-ray and neutron beam scattering on rough surfaces

    International Nuclear Information System (INIS)

    Goray, Leonid I.

    2010-01-01

    The paper presents a comprehensive numerical analysis of x-ray and neutron scattering from finite-conducting rough surfaces which is performed in the frame of the boundary integral equation method in a rigorous formulation for high ratios of characteristic dimension to wavelength. The single integral equation obtained involves boundary integrals of the single and double layer potentials. A more general treatment of the energy conservation law applicable to absorption gratings and rough mirrors is considered. In order to compute the scattering intensity of rough surfaces using the forward electromagnetic solver, Monte Carlo simulation is employed to average the deterministic diffraction grating efficiency due to individual surfaces over an ensemble of realizations. Some rules appropriate for numerical implementation of the theory at small wavelength-to-period ratios are presented. The difference between the rigorous approach and approximations can be clearly seen in specular reflectances of Au mirrors with different roughness parameters at wavelengths where grazing incidence occurs at close to or larger than the critical angle. This difference may give rise to wrong estimates of rms roughness and correlation length if they are obtained by comparing experimental data with calculations. Besides, the rigorous approach permits taking into account any known roughness statistics and allows exact computation of diffuse scattering.

  14. Local secondary-electron emission spectra of graphite and gold surfaces obtained using the Scanning Probe Energy Loss Spectrometer (SPELS)

    International Nuclear Information System (INIS)

    Lawton, J J; Pulisciano, A; Palmer, R E

    2009-01-01

    Secondary-electron emission (SEE) spectra have been obtained with the Scanning Probe Energy Loss Spectrometer at a tip-sample distance of only 50 nm. Such short working distances are required for the best theoretical spatial resolution (<10 nm). The SEE spectra of graphite, obtained as a function of tip bias voltage, are shown to correspond to unoccupied states in the electronic band structure. The SEE spectra of thin gold films demonstrate the capability of identifying (carbonaceous) surface contamination with this technique.

  15. Local secondary-electron emission spectra of graphite and gold surfaces obtained using the Scanning Probe Energy Loss Spectrometer (SPELS)

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, J J; Pulisciano, A; Palmer, R E, E-mail: R.E.Palmer@bham.ac.u [Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom)

    2009-11-25

    Secondary-electron emission (SEE) spectra have been obtained with the Scanning Probe Energy Loss Spectrometer at a tip-sample distance of only 50 nm. Such short working distances are required for the best theoretical spatial resolution (<10 nm). The SEE spectra of graphite, obtained as a function of tip bias voltage, are shown to correspond to unoccupied states in the electronic band structure. The SEE spectra of thin gold films demonstrate the capability of identifying (carbonaceous) surface contamination with this technique.

  16. Field and laboratory calibration of neutron probes for soil moisture measurements on a deep loess chernozem soil

    International Nuclear Information System (INIS)

    Schaecke, B.; Schaecke, E.

    1979-01-01

    In the case of a varying profile structure it is necessary to use different calibration curves and adequate correction factors, respectively. The bulk density of the soil had the greatest influence on the calibration. An increase in bulk density by 0.2 g/cm 3 at a clay content of 18% resulted in an apparent increase in the values of moisture measurements by 1.5 to 2.0% of the volume of water. In naturally stratified soil the humus content of the chernozem horizon, being 3% higher than that of the underlying loess horizon, was found to influence the measuring results obtained by the probe. The calibration curves determined for chernozem and loess horizons in the laboratory agreed well with those obtained in the field. The measured values read from the probe and the gravimetrically determined values of the soil moisture were of great significance in all measured depths of the profile. (author)

  17. Observation of oscillatory radiation induced segregation profiles at grain boundaries in neutron irradiated 316 stainless steel using atom probe tomography

    Science.gov (United States)

    Barr, Christopher M.; Felfer, Peter J.; Cole, James I.; Taheri, Mitra L.

    2018-06-01

    Radiation induced segregation in austenitic Fe-Ni-Cr stainless steels is a key detrimental microstructural modification experienced in the current generation of light water reactors. In particular, Cr depletion at grain boundaries can be a significant factor in irradiation-assisted stress corrosion cracking. Therefore, having a complete knowledge and mechanistic understanding of radiation induced segregation at high dose and after a long thermal history is desired for continued sustainability of existing reactors. Here, we examine a 12% cold worked AISI 316 stainless steel hexagonal duct exposed in the lower dose, outer blanket region of the EBR-II reactor, by using advanced characterization and analysis techniques including atom probe tomography and analytical scanning transmission electron microscopy. Contrary to existing literature, we observe an oscillatory w-shape Cr and M-shape Ni concentration profile at 31 dpa. The presence and characterization through advanced atom probe tomography analysis of the w-shape Cr RIS profile is discussed in the context of the localized GB plane interfacial excess of the other major and minor alloying elements. The key finding of a co-segregation phenomena coupling Cr, Mo, and C is discussed in the context of the existing solute segregation literature under irradiation with emphasis on improved spatial and chemical resolution of atom probe tomography.

  18. Probing astrophysically important states in the 26Mg nucleus to study neutron sources for the s process

    Science.gov (United States)

    Talwar, R.; Adachi, T.; Berg, G. P. A.; Bin, L.; Bisterzo, S.; Couder, M.; deBoer, R. J.; Fang, X.; Fujita, H.; Fujita, Y.; Görres, J.; Hatanaka, K.; Itoh, T.; Kadoya, T.; Long, A.; Miki, K.; Patel, D.; Pignatari, M.; Shimbara, Y.; Tamii, A.; Wiescher, M.; Yamamoto, T.; Yosoi, M.

    2016-05-01

    Background: The 22Ne(α ,n )25Mg reaction is the dominant neutron source for the slow neutron capture process (s process) in massive stars, and contributes, together with 13C (α ,n )16O, to the production of neutrons for the s process in asymptotic giant branch (AGB) stars. However, the reaction is endothermic and competes directly with 22Ne(α ,γ )26Mg radiative capture. The uncertainties for both reactions are large owing to the uncertainty in the level structure of 26Mg near the α and neutron separation energies. These uncertainties affect the s -process nucleosynthesis calculations in theoretical stellar models. Purpose: Indirect studies in the past have been successful in determining the energies and the γ -ray and neutron widths of the 26Mg states in the energy region of interest. But, the high Coulomb barrier hinders a direct measurement of the resonance strengths, which are determined by the α widths for these states. The goal of the present experiments is to identify the critical resonance states and to precisely measure the α widths by α -transfer techniques. Methods: The α -inelastic scattering and α -transfer measurements were performed on a solid 26Mg target and a 22Ne gas target, respectively, using the Grand Raiden Spectrometer at the Research Center for Nuclear Physics in Osaka, Japan. The (α ,α') measurements were performed at 0 .45∘ , 4 .1∘ , 8 .6∘ , and 11 .1∘ and the (6Li,d ) measurements at 0∘ and 10∘. The scattered α particles and deuterons were detected by the focal plane detection system consisting of multiwire drift chambers and plastic scintillators. The focal plane energy calibration allowed the study of 26Mg levels from Ex = 7.69-12.06 MeV in the (α ,α') measurement and Ex = 7.36-11.32 MeV in the (6Li,d ) measurement. Results: Six levels (Ex = 10717, 10822, 10951, 11085, 11167, and 11317 keV) were observed above the α threshold in the region of interest (10.61-11.32 MeV). The α widths were calculated for these

  19. Electronic state of PuCoGa5 and NpCoGa5 as probed by polarized neutrons.

    Science.gov (United States)

    Hiess, A; Stunault, A; Colineau, E; Rebizant, J; Wastin, F; Caciuffo, R; Lander, G H

    2008-02-22

    By using single crystals and polarized neutrons, we have measured the orbital and spin components of the microscopic magnetization in the paramagnetic state of NpCoGa(5) and PuCoGa(5). The microscopic magnetization of NpCoGa(5) agrees with that observed in bulk susceptibility measurements and the magnetic moment has spin and orbital contributions as expected for intermediate coupling. In contrast, for PuCoGa(5), which is a superconductor with a high transition temperature, the microscopic magnetization in the paramagnetic state is small, temperature-independent, and significantly below the value found with bulk techniques at low temperatures. The orbital moment dominates the magnetization.

  20. The effect of surface texture on total reflection of neutrons and X-rays from modified interfaces

    DEFF Research Database (Denmark)

    Goldar, A.; Roser, S.J.; Hughes, A.

    2002-01-01

    X-ray and neutron scattering from macroscopically rough surfaces and interfaces is considered and a new method of analysis based on the variation of the shape of the total reflection edge in the reflectivity profile is proposed. It was shown that in the limit that the correlation length and the h......X-ray and neutron scattering from macroscopically rough surfaces and interfaces is considered and a new method of analysis based on the variation of the shape of the total reflection edge in the reflectivity profile is proposed. It was shown that in the limit that the correlation length...... and the height of the surface roughness are larger than the wavelength (at least 100 times bigger) of the incoming beam, the total reflection edge in the reflection profile becomes rounded. This technique allows direct analysis of the variation of the reflectivity pro le in terms of the structure of the surface...

  1. Surface Crack Detection for Carbon Fiber Reinforced Plastic Materials Using Pulsed Eddy Current Based on Rectangular Differential Probe

    Directory of Open Access Journals (Sweden)

    Jialong Wu

    2014-01-01

    Full Text Available Aiming at the surface defect inspection of carbon fiber reinforced composite, the differential and the direct measurement finite element simulation models of pulsed eddy current flaw detection were built. The principle of differential pulsed eddy current detection was analyzed and the sensitivity of defect detection was compared through two kinds of measurements. The validity of simulation results was demonstrated by experiments. The simulation and experimental results show that the pulsed eddy current detection method based on rectangular differential probe can effectively improve the sensitivity of surface defect detection of carbon fiber reinforced composite material.

  2. Burst Oscillations: A New Spin on Neutron Stars

    Science.gov (United States)

    Strohmayer, Tod

    2007-01-01

    Observations with NASA's Rossi X-ray Timing Explorer (RXTE) have shown that the X-ray flux during thermonuclear X-ray bursts fr-om accreting neutron stars is often strongly pulsed at frequencies as high as 620 Hz. We now know that these oscillations are produced by spin modulation of the thermonuclear flux from the neutron star surface. In addition to revealing the spin frequency, they provide new ways to probe the properties and physics of accreting neutron stars. I will briefly review our current observational and theoretical understanding of these oscillations and discuss what they are telling us about neutron stars.

  3. Probing molecular dynamics of metal borohydrides on the surface of mesoporous scaffolds by multinuclear high resolution solid state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Son-Jong, E-mail: Sonjong@cheme.caltech.edu [Division of Chemistry and Chemical Eng., California Institute of Technology, Pasadena, CA 91125 (United States); Lee, Hyun-Sook [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); To, Magnus [Division of Chemistry and Chemical Eng., California Institute of Technology, Pasadena, CA 91125 (United States); Lee, Young-Su; Cho, Young Whan [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Choi, Hyungkeun; Kim, Chul [Department of Chemistry, Hannam University, Daejeon 305-811 (Korea, Republic of)

    2015-10-05

    Graphical abstract: In situ variable temperature multinuclear solid state NMR allows to probe surface wetting, diffusivity, and confinement of metal borohydrides into nanopores. - Abstract: Understanding of surface interactions between borohydride molecules and the surfaces of porous supports have gained growing attention for successful development of nano-confinement engineering. By use of in situ variable temperature (VT) magic angle spinning (MAS) NMR, molecular mobility changes of LiBH{sub 4} crystalline solid has been investigated in the presence of silica based and carbonaceous surfaces. Spin–spin J-coupling of {sup 1}H–{sup 11}B in LiBH{sub 4} was monitored in series of VT NMR spectra to probe translational mobility of LiBH{sub 4} that appeared to be greatly enhanced upon surface contact. Such enhanced diffusivity was found to be effective in the formation of solid solution and co-confinement with other metal borohydrides. Co-confinement of LiBH{sub 4}–Ca(BH{sub 4}){sub 2} mixture was demonstrated at temperature as low as 100 °C, much lower than the reported bulk eutectic melting temperature. The discovery adds a novel property of LiBH{sub 4} that has been proven to be highly versatile in many energy related applications.

  4. Surface density dependence of PCR amplicon hybridization on PNA/DNA probe layers

    DEFF Research Database (Denmark)

    Yao, Danfeng; Kim, Junyoung; Yu, Fang

    2005-01-01

    at an intermediate sodium concentration (approximately 100 mM). These effects were mainly ascribed to the electrostatic cross talk among the hybridized DNA molecules and the secondary structure of PCR amplicons. For the negatively charged DNA probes, the hybridization reaction was subjected additionally to the DNA....../DNA electrostatic barrier, particularly in lower ionic strength range (e.g., 10 approximately 150 mM Na(+)). The electrostatic cross talk was shown to be largely reduced if the PNA probe layer was sufficiently diluted by following a strategic templated immobilization method. As a consequence, a pseudo...

  5. Surface harmonics method for two-dimensional time-dependent neutron transport problems of square-lattice nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Boyarinov, V. F.; Kondrushin, A. E.; Fomichenko, P. A. [National Research Centre Kurchatov Institute, Kurchatov Sq. 1, Moscow (Russian Federation)

    2013-07-01

    Time-dependent equations of the Surface Harmonics Method (SHM) have been derived from the time-dependent neutron transport equation with explicit representation of delayed neutrons for solving the two-dimensional time-dependent problems. These equations have been realized in the SUHAM-TD code. The TWIGL benchmark problem has been used for verification of the SUHAM-TD code. The results of the study showed that computational costs required to achieve necessary accuracy of the solution can be an order of magnitude less than with the use of the conventional finite difference method (FDM). (authors)

  6. Investigation of the surface potential of TiO2 (110) by frequency-modulation Kelvin probe force microscopy

    Science.gov (United States)

    Kou, Lili; Li, Yan Jun; Kamijyo, Takeshi; Naitoh, Yoshitaka; Sugawara, Yasuhiro

    2016-12-01

    We investigate the surface potential distribution on a TiO2 (110)-1 × 1 surface by Kelvin probe force microscopy (KPFM) and atom-dependent bias-distance spectroscopic mapping. The experimental results demonstrate that the local contact potential difference increases on twofold-coordinated oxygen sites, and decreases on OH defects and fivefold-coordinated Ti sites. We propose a qualitative model to explain the origin of the surface potential of TiO2 (110). We qualitatively calculate the surface potential induced by chemical potential and permanent surface dipole. The calculated results agree with our experimental ones. Therefore, we suggest that the surface potential of TiO2 (110) is dominated not only by the permanent surface dipole between the tip apex atom and surface, but also by the dipoles induced by the chemical interaction between the tip and sample. The KPFM technique demonstrate the possibility of investigation of the charge transfer phenomenon on TiO2 surface under gas conditions. It is useful for the elucidation of the mechanism of the catalytic reactions.

  7. Glitches as probes of neutron star internal structure and dynamics: Effects of the superfluid-superconducting core

    Science.gov (United States)

    Gügercinoğlu, Erbil

    2017-12-01

    Glitches, sudden spin-up of pulsars with subsequent recovery, provide us with a unique opportunity to investigate various physical processes, including the crust-core coupling, distribution of reservoir angular momentum within different internal layers, spin-up in neutral and charged superfluids and constraining the equation of state of the neutron star (NS) matter. In this work, depending on the dynamic interaction between the vortex lines and the nuclei in the inner crust, and between the vortex lines and the magnetic flux tubes in the outer core, various types of relaxation behavior are obtained and confronted with the observations. It is shown that the glitches have strong potential to deduce information about the cooling behavior and interior magnetic field configuration of NSs. Some implications of the relative importance of the external spin-down torques and the superfluid internal torques for recently observed unusual glitches are also discussed.

  8. Effect of surfactant excess on the stability of low-polarity ferrofluids probed by small-angle neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Petrenko, V. I., E-mail: vip@nf.jinr.ru; Avdeev, M. V. [Joint Institute for Nuclear Research (Russian Federation); Bulavin, L. A. [Taras Shevchenko National University of Kyiv (Ukraine); Almasy, L. [Hungarian Academy of Science, Wigner Research Centre for Physics (Hungary); Grigoryeva, N. A. [St. Petersburg State University (Russian Federation); Aksenov, V. L. [National Research Centre “Kurchatov Institute”, Konstantinov Petersburg Nuclear Physics Institute (Russian Federation)

    2016-01-15

    The structures of ferrofluids (FFs) based on nonpolar solvent decahydronaphthalene, stabilized by saturated monocarboxylic acids with hydrocarbon chains of different lengths, C16 (palmitic acid) and ?12 (lauric acid), with an excess of acid molecules, have been studied by small-angle neutron scattering. It is found that the addition of acid to an initially stable system with optimal composition leads to more significant structural changes (related to aggregation) than those observed previously for this class of FFs. A comparison of the influence of monocarboxylic acids on the stability of nonpolar FFs suggests that the enhancement of aggregation is much more pronounced in the case of palmitic acid excess. This fact confirms the conclusion of previous studies, according to which an increase in the hydrocarbon chain length in a saturated acid reduces the efficiency of the corresponding FF stabilization.

  9. Polarized Neutron Diffraction to Probe Local Magnetic Anisotropy of a Low-Spin Fe(III) Complex.

    Science.gov (United States)

    Ridier, Karl; Mondal, Abhishake; Boilleau, Corentin; Cador, Olivier; Gillon, Béatrice; Chaboussant, Grégory; Le Guennic, Boris; Costuas, Karine; Lescouëzec, Rodrigue

    2016-03-14

    We have determined by polarized neutron diffraction (PND) the low-temperature molecular magnetic susceptibility tensor of the anisotropic low-spin complex PPh4 [Fe(III) (Tp)(CN)3]⋅H2O. We found the existence of a pronounced molecular easy magnetization axis, almost parallel to the C3 pseudo-axis of the molecule, which also corresponds to a trigonal elongation direction of the octahedral coordination sphere of the Fe(III) ion. The PND results are coherent with electron paramagnetic resonance (EPR) spectroscopy, magnetometry, and ab initio investigations. Through this particular example, we demonstrate the capabilities of PND to provide a unique, direct, and straightforward picture of the magnetic anisotropy and susceptibility tensors, offering a clear-cut way to establish magneto-structural correlations in paramagnetic molecular complexes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Probing the density content of the nuclear symmetry energy

    Indian Academy of Sciences (India)

    Abstract. The nature of equation of state for the neutron star matter is crucially governed by the density dependence of the nuclear symmetry energy. We attempt to probe the behaviour of the nuclear symmetry energy around the saturation density by exploiting the empirical values for volume and surface symmetry energy ...

  11. Near-field optical microscopy of localized excitations on rough surfaces: influence of a probe

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.

    1999-01-01

    Starting from the general principles of near-field optical microscopy. I consider the influence of a probe when being used to image localized dipolar excitations and suggest a way of evaluating the perturbation thus introduced. Using the rigorous microscopic (electric) point-dipole description, I...

  12. Note: Proton irradiation at kilowatt-power and neutron production from a free-surface liquid-lithium target

    Energy Technology Data Exchange (ETDEWEB)

    Halfon, S.; Feinberg, G. [Soreq NRC, Yavne 81800 (Israel); Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Arenshtam, A.; Kijel, D.; Weissman, L.; Aviv, O.; Berkovits, D.; Dudovitch, O.; Eisen, Y.; Eliyahu, I.; Haquin, G.; Hazenshprung, N.; Kreisel, A.; Mardor, I.; Shimel, G.; Shor, A.; Silverman, I.; Yungrais, Z. [Soreq NRC, Yavne 81800 (Israel); Paul, M., E-mail: paul@vms.huji.ac.il; Tessler, M. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)

    2014-05-15

    The free-surface Liquid-Lithium Target, recently developed at Soreq Applied Research Accelerator Facility (SARAF), was successfully used with a 1.9 MeV, 1.2 mA (2.3 kW) continuous-wave proton beam. Neutrons (∼2 × 10{sup 10} n/s having a peak energy of ∼27 keV) from the {sup 7}Li(p,n){sup 7}Be reaction were detected with a fission-chamber detector and by gold activation targets positioned in the forward direction. The setup is being used for nuclear astrophysics experiments to study neutron-induced reactions at stellar energies and to demonstrate the feasibility of accelerator-based boron neutron capture therapy.

  13. Production of a faithful realistic phantom to human head and thermal neutron flux measurement on the brain surface. Cooperative research

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Kazuyoshi; Kumada, Hiroaki; Kishi, Toshiaki; Torii, Yoshiya; Uchiyama, Junzo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Endo, Kiyoshi; Yamamoto, Tetsuya; Matsumura, Akira; Nose, Tadao [Tsukuba Univ., Tsukuba, Ibaraki (Japan)

    2002-12-01

    Thermal neutron flux is determined using the gold wires in current BNCT irradiation, so evaluation of arbitrary points after the irradiation is limited in the quantity of these detectors. In order to make up for the weakness, dose estimation of a patient is simulated by a computational dose calculation supporting system. In another way without computer simulation, a medical irradiation condition can be replicate experimentally using of realistic phantom which was produced from CT images by rapid prototyping technique. This phantom was irradiated at a same JRR-4 neutron beam as clinical irradiation condition of the patient and the thermal neutron distribution on the brain surface was measured in detail. This experimental evaluation technique using a realistic phantom is applicable to in vitro cell irradiation experiments for radiation biological effects as well as in-phantom experiments for dosimetry under the nearly medical irradiation condition of patient. (author)

  14. Production of a faithful realistic phantom to human head and thermal neutron flux measurement on the brain surface. Cooperative research

    CERN Document Server

    Yamamoto, K; Kishi, T; Kumada, H; Matsumura, A; Nose, T; Torii, Y; Uchiyama, J; Yamamoto, T

    2002-01-01

    Thermal neutron flux is determined using the gold wires in current BNCT irradiation, so evaluation of arbitrary points after the irradiation is limited in the quantity of these detectors. In order to make up for the weakness, dose estimation of a patient is simulated by a computational dose calculation supporting system. In another way without computer simulation, a medical irradiation condition can be replicate experimentally using of realistic phantom which was produced from CT images by rapid prototyping technique. This phantom was irradiated at a same JRR-4 neutron beam as clinical irradiation condition of the patient and the thermal neutron distribution on the brain surface was measured in detail. This experimental evaluation technique using a realistic phantom is applicable to in vitro cell irradiation experiments for radiation biological effects as well as in-phantom experiments for dosimetry under the nearly medical irradiation condition of patient.

  15. Neutron moisture gaging of agricultural soil

    International Nuclear Information System (INIS)

    Pospisil, S.; Janout, Z.; Kovacik, M.

    1987-01-01

    The design is described of a neutron moisture gage which consists of a measuring probe, neutron detector, small electronic recording device and a 241 Am-Be radionuclide source. The neutron detector consists of a surface barrier semiconductor silicon detector and a conversion layer of lithium fluoride. The detection of triton which is the reaction product of lithium with neutrons by the silicon detector is manifested as a voltage pulse. The detector has low sensitivity for fast neutrons and for gamma radiation and is suitable for determining moisture values in large volume samples. Verification and calibration measurements were carried out of chernozem, brown soil and podzolic soils in four series. The results are tabulated. Errors of measurement range between 0.8 to 1.0%. The precision of measurement could be improved by the calibration of the device for any type of soil. (E.S.). 4 tabs., 6 refs., 5 figs

  16. Sensing surface mechanical deformation using active probes driven by motor proteins

    Science.gov (United States)

    Inoue, Daisuke; Nitta, Takahiro; Kabir, Arif Md. Rashedul; Sada, Kazuki; Gong, Jian Ping; Konagaya, Akihiko; Kakugo, Akira

    2016-01-01

    Studying mechanical deformation at the surface of soft materials has been challenging due to the difficulty in separating surface deformation from the bulk elasticity of the materials. Here, we introduce a new approach for studying the surface mechanical deformation of a soft material by utilizing a large number of self-propelled microprobes driven by motor proteins on the surface of the material. Information about the surface mechanical deformation of the soft material is obtained through changes in mobility of the microprobes wandering across the surface of the soft material. The active microprobes respond to mechanical deformation of the surface and readily change their velocity and direction depending on the extent and mode of surface deformation. This highly parallel and reliable method of sensing mechanical deformation at the surface of soft materials is expected to find applications that explore surface mechanics of soft materials and consequently would greatly benefit the surface science. PMID:27694937

  17. Simultaneous impact of neutron irradiation and sputtering on the surface structure of self–damaged ITER–grade tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Belyaeva, A. I., E-mail: aibelyaeva@mail.ru; Savchenko, A. A. [National Technical University “Kharkov Politechnical Institute”, Kharkov, 61002 (Ukraine); Galuza, A. A.; Kolenov, I. V. [Institute of Electrophysics and Radiation Technologies, National Academy of Science of Ukraine, Kharkov, 61024 (Ukraine)

    2014-07-15

    Simultaneous effects of neutron irradiation and long–term sputtering on the surface relief of ITER–grade tungsten were studied. The effects of neutron–induced displacement damage have been simulated by irradiation of tungsten target with W{sup 6+} ions of 20 MeV energy. Ar{sup +} ions with energy 600 eV were used as imitation of charge exchange atoms in ITER. The surface relief was studied after each sputtering act. The singularity in the WJ–IG surface relief was ascertained experimentally at the first time, which determines the law of roughness extension under sputtering. As follows from the experimental data, the neutron irradiation has not to make a decisive additional contribution in the processes developing under impact of charge exchange atoms only.

  18. A novel optical tool for controlling and probing ultrafast surface dynamics

    International Nuclear Information System (INIS)

    Yang, Yudong

    2017-12-01

    Ultrashort pulse laser sources have been greatly developed over the past few decades. The available pulse duration has been reduced to the single-cycle pulse regime. The discovery of high harmonic generation has freed us from the limitation of the laser wavelength. Moreover, the demonstration of isolated attosecond pulse generation has indicated the advent of the attosecond science era. Attosecond pulses undoubtedly allow one to study ultrafast dynamics with unprecedented time resolution. However, physical systems with genuine attosecond time scale dynamics are rather challenging to find. Ultrafast surface charge transfer, which is an important process in photochemistry and electrochemistry, is a good candidate experimental system exhibiting attosecond electronic dynamics. Specifically, the ultrafast surface charge transfer on the c(4 x 2)S/Ru(0001) surface was previously studied and the charge transfer time inferred to be 320 as using core-hole clock spectroscopy at a synchrotron facility. In order to measure this benchmark attosecond electronic dynamics with real time-resolving methods, pump pulses centered at 160 eV and probe pulses centered at 40 eV are required. To this end, a dedicated attosecond experimental beamline including an ultrashort laser pulse source and an attosecond pulse generation and characterization setup has been designed and is being developed. The author of this thesis was responsible for the construction of the attosecond experimental beamline which will be used ultrafast surface charge transfer studies. In this thesis, a completely functional attosecond extreme ultraviolet (XUV) beamline, which includes a few-cycle laser pulse source, an attosecond pulse generation and characterization setup, is described. A commercial Ti:sapphire-based chirped-pulse amplification (CPA) laser system is the overall source of the beamline. The laser system is actively carrier-envelope phase (CEP) stabilized and the output pulse duration is ∝35 fs. The

  19. A novel optical tool for controlling and probing ultrafast surface dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yudong

    2017-12-15

    Ultrashort pulse laser sources have been greatly developed over the past few decades. The available pulse duration has been reduced to the single-cycle pulse regime. The discovery of high harmonic generation has freed us from the limitation of the laser wavelength. Moreover, the demonstration of isolated attosecond pulse generation has indicated the advent of the attosecond science era. Attosecond pulses undoubtedly allow one to study ultrafast dynamics with unprecedented time resolution. However, physical systems with genuine attosecond time scale dynamics are rather challenging to find. Ultrafast surface charge transfer, which is an important process in photochemistry and electrochemistry, is a good candidate experimental system exhibiting attosecond electronic dynamics. Specifically, the ultrafast surface charge transfer on the c(4 x 2)S/Ru(0001) surface was previously studied and the charge transfer time inferred to be 320 as using core-hole clock spectroscopy at a synchrotron facility. In order to measure this benchmark attosecond electronic dynamics with real time-resolving methods, pump pulses centered at 160 eV and probe pulses centered at 40 eV are required. To this end, a dedicated attosecond experimental beamline including an ultrashort laser pulse source and an attosecond pulse generation and characterization setup has been designed and is being developed. The author of this thesis was responsible for the construction of the attosecond experimental beamline which will be used ultrafast surface charge transfer studies. In this thesis, a completely functional attosecond extreme ultraviolet (XUV) beamline, which includes a few-cycle laser pulse source, an attosecond pulse generation and characterization setup, is described. A commercial Ti:sapphire-based chirped-pulse amplification (CPA) laser system is the overall source of the beamline. The laser system is actively carrier-envelope phase (CEP) stabilized and the output pulse duration is ∝35 fs. The

  20. An integrated high temperature environmental cell for atom probe tomography studies of gas-surface reactions: Instrumentation and results

    International Nuclear Information System (INIS)

    Dumpala, S.; Broderick, S.R.; Bagot, P.A.J.; Rajan, K.

    2014-01-01

    An integrated environmental cell has been designed and developed for the latest generation of Atom Probe Tomography LEAP™ instruments, allowing controlled exposure of samples to gases at high temperatures. Following treatment, samples can be transferred through the LEAP vacuum system for subsequent APT analysis, which provides detailed information on changes to chemical microstructures following the reactions with near-atomic resolution. A full description of the cell is presented, along with some sample results on the oxidation of aluminum and two platinum-group alloys, demonstrating the capability of combining exposure/characterization functionality in a single instrument. - Highlights: • Designed and built atom probe environmental cell for in situ reactions. • Investigated Al oxidation, and demonstrated improvement with new cell. • in situ APT analysis of Pt-alloys showed surface segregation of Rh and Ir

  1. Fiber optic probe enabled by surface-enhanced Raman scattering for early diagnosis of potential acute rejection of kidney transplant

    Science.gov (United States)

    Chi, Jingmao; Chen, Hui; Tolias, Peter; Du, Henry

    2014-06-01

    We have explored the use of a fiber-optic probe with surface-enhanced Raman scattering (SERS) sensing modality for early, noninvasive and, rapid diagnosis of potential renal acute rejection (AR) and other renal graft dysfunction of kidney transplant patients. Multimode silica optical fiber immobilized with colloidal Ag nanoparticles at the distal end was used for SERS measurements of as-collected urine samples at 632.8 nm excitation wavelength. All patients with abnormal renal graft function (3 AR episodes and 2 graft failure episodes) who were clinically diagnosed independently show common unique SERS spectral features in the urines collected just one day after transplant. SERS-based fiber-optic probe has excellent potential to be a bedside tool for early diagnosis of kidney transplant patients for timely medical intervention of patients at high risk of transplant dysfunction.

  2. Oxidation of hydrogen-passivated silicon surfaces by scanning near-field optical lithography using uncoated and aluminum-coated fiber probes

    DEFF Research Database (Denmark)

    Madsen, Steen; Bozhevolnyi, Sergey I.; Birkelund, Karen

    1997-01-01

    Optically induced oxidation of hydrogen-passivated silicon surfaces using a scanning near-field optical microscope was achieved with both uncoated and aluminum-coated fiber probes. Line scans on amorphous silicon using uncoated fiber probes display a three-peak profile after etching in potassium...... hydroxide. Numerical simulations of the electromagnetic field around the probe-sample interaction region are used to explain the experimental observations. With an aluminum-coated fiber probe, lines of 35 nm in width were transferred into the amorphous silicon layer. (C) 1997 American Institute of Physics....

  3. Methodical comparison of neutron depth probes and long-term soil moisture measurements on loess, sandy loess, and boulder clay

    International Nuclear Information System (INIS)

    Neue, H.U.

    1980-01-01

    Three measuring instruments were tested: 0.05 mCi Cf-252, 100 mCi Am-241/Be, 500 mCi Am-241/Be. The advantages - measurement in undisturbed soil profiles, large depths of measurement, reproducibility of measurements in the same place over several years - and the disadvantages - radiation protection, resolution, variations of measured volume in dependence of moisture, background influences etc. - have been critically checked by experiment. In addition, annual soil moisture curves have been measured over two years by parallel use of the free probes on a loess, sandy loess, and boulder clay site. The results were compared and discussed with a view to the soil water dynamics of these sites. (orig./HP) [de

  4. Using Force to Probe Single-Molecule Receptor-Cytoskeletal Anchoring Beneath the Surface of a Living Cell

    DEFF Research Database (Denmark)

    Evans, Evan; Kinoshita, Koji

    2007-01-01

    -cytoskeletal unbinding increased exponentially with the level of force, suggesting disruption at a site of single-molecule interaction. Since many important enzymes and signaling molecules are closely associated with a membrane receptor-cytoskeletal linkage, pulling on a receptor could alter interactions among its......The ligation of cell surface receptors often communicates a signal that initiates a cytoplasmic chemical cascade to implement an important cell function. Less well understood is how physical stress applied to a cell surface adhesive bond propagates throughout the cytostructure to catalyze...... or trigger important steps in these chemical processes. Probing the nanoscale impact of pulling on cell surface bonds, we discovered that receptors frequently detach prematurely from the interior cytostructure prior to failure of the exterior adhesive bond [Evans, E., Heinrich, V., Leung, A., and Kinoshita...

  5. Surface characterization of superconductive Nd1Ba2Cu3Oy thin films using scanning probe microscopes

    International Nuclear Information System (INIS)

    Ting, W.; Badaye, M.; Itti, R.; Morishita, T.; Koshizuka, N.; Tanaka, S.

    1996-01-01

    Recently, superconductive Nd 1 Ba 2 Cu 3 O y (Nd123) thin films with high superconducting transition temperature (T c ) have been successfully fabricated at the authors institute employing the standard laser ablation method. In this paper, they report parts of the results of surface characterization of the Nd123 thin films using an ultrahigh vacuum scanning tunneling microscope/spectroscopy (UHV-STM/STS) and an atomic force microscope (AFM) system operated in air. Clear spiral pattern is observed on the surfaces of Nd123 thin films by STM and AFM, suggesting that films are formed by two-dimensional island growth mode at the final growing stage. Contour plots of the spirals show that the step heights of the spirals are not always the integer or half integer numbers of the c-axis parameter of the structure. This implies that the surface natural termination layer of the films may not be unique. Surface atomic images of the as-prepared Nd123 thin films are obtained employing both STM and AFM. STS measurements show that most of the surfaces are semiconductive, or sometimes even metallic. The results of STS measurements together with the fact that they are able to see the surface atomic images using scanning probe microscopes suggest that exposure to air does not cause serious degradation to the as-prepared surfaces of Nd123 thin films

  6. The spin chirality in MnSi single crystal probed by small angle scattering with polarized neutrons

    International Nuclear Information System (INIS)

    Okorokov, A.I.; Grigoriev, S.V.; Chetverikov, Yu.O.; Georgii, R.; Boeni, P.; Eckerlebe, H.; Pranzas, K.; Roessli, B.

    2004-01-01

    The weak itinerant ferromagnet MnSi orders with a left-handed helical spin structure below T C =29 K. The helicity with a vector m=[S 1 xS 2 ]/S 2 along the crystallographic axis [1 1 1] is realized by an antisymmetric Dzyaloshinski-Moriya interaction. The small angle diffraction study with polarized neutrons on a single MnSi crystal was performed within the temperature range from 10 K to T C and the magnetic field B from 1 to 350 mT. The single crystal was oriented in such a way that two axes [1 1 1] and [1 1 -1] were set in a plane perpendicular to the incident beam. Four major diffraction peaks at ±q 1 and ±q 2 along the axes and four minor peaks at q=±q 1 ±q 2 were observed. The intensity I p =I(+P 0 )+I(-P 0 ), the polarization P p =[I(+P 0 )-I(-P 0 )]/I p and the position q p of the peaks were measured as a function of the temperature and the magnetic field. From intensity of the peaks the chiral critical exponent is obtained as β=0.47±0.04

  7. Neutron Reflection Study of Surface Adsorption of Fc, Fab, and the Whole mAb.

    Science.gov (United States)

    Li, Zongyi; Li, Ruiheng; Smith, Charles; Pan, Fang; Campana, Mario; Webster, John R P; van der Walle, Christopher F; Uddin, Shahid; Bishop, Steve M; Narwal, Rojaramani; Warwicker, Jim; Lu, Jian Ren

    2017-07-12

    Characterizing the influence of fragment crystallization (Fc) and antigen-binding fragment (Fab) on monoclonal antibody (mAb) adsorption at the air/water interface is an important step to understanding liquid mAb drug product stability during manufacture, shipping, and storage. Here, neutron reflection is used to study the air/water adsorption of a mAb and its Fc and Fab fragments. By varying the isotopic contrast, the adsorbed amount, thickness, orientation, and immersion of the adsorbed layers could be determined unambiguously. While Fc adsorption reached saturation within the hour, its surface adsorbed amount showed little variation with bulk concentration. In contrast, Fab adsorption was slower and the adsorbed amount was concentration dependent. The much higher Fc adsorption, as compared to Fab, was linked to its lower surface charge. Time and concentration dependence of mAb adsorption was dominated by Fab behavior, although both Fab and Fc behaviors contributed to the amount of mAb adsorbed. Changing the pH from 5.5 to 8.8 did not much perturb the adsorbed amount of Fc, Fab, or mAb. However, a small decrease in adsorption was observed for the Fc over pH 8-8.8 and vice versa for the Fab and mAb, consistent with a dominant Fab behavior. As bulk concentration increased from 5 to 50 ppm, the thicknesses of the Fc layers were almost constant at 40 Å, while Fab and mAb layers increased from 45 to 50 Å. These results imply that the adsorbed mAb, Fc, and Fab all retained their globular structures and were oriented with their short axial lengths perpendicular to the interface.

  8. Probing droplets with biological colloidal suspensions on smart surfaces by synchrotron radiation micro- and nano-beams

    KAUST Repository

    Marinaro, Giovanni

    2015-03-01

    Droplets with colloidal biological suspensions evaporating on substrates with defined wetting properties generate confined environments for initiating aggregation and self-assembly processes. We describe smart micro- and nanostructured surfaces, optimized for probing single droplets and residues by synchrotron radiation micro- and nanobeam diffraction techniques. Applications are presented for Ac-IVD and β-amyloid (1-42) peptides capable of forming cross-β sheet structures. Complementary synchrotron radiation FTIR microspectroscopy addresses secondary structure formation. The high synchrotron radiation source brilliance enables fast raster-scan experiments. © 2015 Elsevier Ltd.

  9. Probing droplets with biological colloidal suspensions on smart surfaces by synchrotron radiation micro- and nano-beams

    KAUST Repository

    Marinaro, Giovanni; Accardo, Angelo; Benseny-Cases, Nú ria; Burghammer, Manfred C.; Castillo-Michel, Hiram A.; Cotte, Marine; Dante, Silvia; De Angelis, Francesco De; Di Cola, Emanuela; Di Fabrizio, Enzo M.; Hauser, C.; Riekel, Christian

    2015-01-01

    Droplets with colloidal biological suspensions evaporating on substrates with defined wetting properties generate confined environments for initiating aggregation and self-assembly processes. We describe smart micro- and nanostructured surfaces, optimized for probing single droplets and residues by synchrotron radiation micro- and nanobeam diffraction techniques. Applications are presented for Ac-IVD and β-amyloid (1-42) peptides capable of forming cross-β sheet structures. Complementary synchrotron radiation FTIR microspectroscopy addresses secondary structure formation. The high synchrotron radiation source brilliance enables fast raster-scan experiments. © 2015 Elsevier Ltd.

  10. Metal nanoinks as chemically stable surface enhanced scattering (SERS) probes for the analysis of blue BIC ballpoint pens.

    Science.gov (United States)

    Alyami, A; Saviello, D; McAuliffe, M A P; Mirabile, A; Lewis, L; Iacopino, D

    2017-06-07

    Metal nanoinks constituted by Ag nanoparticles and Au nanorods were employed as probes for the Surface Enhanced Raman Scattering (SERS) analysis of a blue BIC ballpoint pen. The dye components of the pen ink were first separated by thin layer chromatography (TLC) and subsequently analysed by SERS at illumination wavelengths of 514 nm and 785 nm. Compared to normal Raman conditions, enhanced spectra were obtained for all separated spots, allowing easy identification of phthalocyanine Blue 38 and triarylene crystal violet in the ink mixture. A combination of effects such as molecular resonance, electromagnetic and chemical effects were the contributing factors to the generation of spectra enhanced compared to normal Raman conditions. Enhancement factors (EFs) between 5 × 10 3 and 3 × 10 6 were obtained, depending on the combination of SERS probes and laser illumination used. In contrast to previous conflicting reports, the metal nanoinks were chemically stable, allowing the collection of reproducible spectra for days after deposition on TLC plates. In addition and in advance to previously reported SERS probes, no need for additional aggregating agents or correction of electrostatic charge was necessary to induce the generation of enhanced SERS spectra.

  11. Probing the adsorption mechanism in thiamazole bound to the silver surface with Surface-enhanced Raman Scattering and DFT

    Science.gov (United States)

    Biswas, Nandita; Thomas, Susy; Sarkar, Anjana; Mukherjee, Tulsi; Kapoor, Sudhir

    2009-09-01

    Surface-enhanced Raman scattering (SERS) of thiamazole have been investigated in aqueous solution. Thiamazole is an important anti-thyroid drug that is used in the treatment of hyperthyroidism (over activity of the thyroid gland). Due to its medicinal importance, the surface adsorption properties of thiamazole have been studied. The experimental Raman and SERS data are supported with DFT calculations using B3LYP functional with LANL2DZ basis set. From the SERS spectra as well as theoretical calculations, it has been inferred that thiamazole is chemisorbed to the silver surface directly through the sulphur atom and the ring N atom, with a tilted orientation.

  12. Development of a uniform eddy current multi-probe for flaw inspection on a curved surface shape portion and estimation of crack shape

    International Nuclear Information System (INIS)

    Fukuoka, Katsuhiro; Hashimoto, Mitsuo

    2009-01-01

    The establishment of non-destructive inspection technology for plant structures is necessary, since the occurrence of cracks has been reported in some nuclear power plants. In this research, a uniform eddy current multi-probe to inspect cracks on a curved structure was developed. We designed exciting coils of this probe, considering the shape of the curved structure, so that the eddy current flows uniformly. Pick-up coils were arranged on a flexible printed circuit board to fit on the curved surface shape portion. The detection characteristics for EDM (electrical discharge machining) slits provided on the curved surface shape portion of the specimen were evaluated. The clear signals for the EDM slits provided on the curved surface which had a curvature radius of 25 mm were obtained by this probe. We confirmed that the crack shape could be estimated by detecting the signals from the developed probe. (author)

  13. Surface transport mechanisms in molecular glasses probed by the exposure of nano-particles

    Science.gov (United States)

    Ruan, Shigang; Musumeci, Daniele; Zhang, Wei; Gujral, Ankit; Ediger, M. D.; Yu, Lian

    2017-05-01

    For a glass-forming liquid, the mechanism by which its surface contour evolves can change from bulk viscous flow at high temperatures to surface diffusion at low temperatures. We show that this mechanistic change can be conveniently detected by the exposure of nano-particles native in the material. Despite its high chemical purity, the often-studied molecular glass indomethacin contains low-concentration particles approximately 100 nm in size and 0.3% in volume fraction. Similar particles are present in polystyrene, another often-used model. In the surface-diffusion regime, particles are gradually exposed in regions vacated by host molecules, for example, the peak of a surface grating and the depletion zone near a surface crystal. In the viscous-flow regime, particle exposure is not observed. The surface contour around an exposed particle widens over time in a self-similar manner as 3 (Bt)1/4, where B is a surface mobility constant and the same constant obtained by surface grating decay. This work suggests that in a binary system composed of slow- and fast-diffusing molecules, slow-diffusing molecules can be stranded in surface regions vacated by fast-diffusing molecules, effectively leading to phase separation.

  14. Single DNA molecules as probes for interrogating silica surfaces after various chemical treatments

    International Nuclear Information System (INIS)

    Liu Xia; Wu Zhan; Nie Huagui; Liu Ziling; He Yan; Yeung, E.S.

    2007-01-01

    We examined the adsorption of single YOYO-1-labeled λ-DNA molecules at glass surfaces after treatment with various chemical cleaning methods by using total internal reflection fluorescence microscopy (TIRFM). The characteristics of these surfaces were further assessed using contact angle (CA) measurements and atomic force microscopy (AFM). By recording the real-time dynamic motion of DNA molecules at the liquid/solid interface, subtle differences in adsorption affinities were revealed. The results indicate that the driving force for adsorption of DNA molecules on glass surfaces is mainly hydrophobic interaction. We also found that surface topography plays a role in the adsorption dynamics

  15. Neutron holography

    International Nuclear Information System (INIS)

    Beynon, T.D.

    1986-01-01

    the paper concerns neutron holography, which allows an image to be constructed of the surfaces, as well as the interiors, of objects. The technique of neutron holography and its applications are described. Present and future use of the method is briefly outlined. (U.K.)

  16. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-07-01

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

  17. Neutron scattering. Lectures

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  18. Device for positioning ultrasonic probes and/or television cameras on the outer surface of reactor pressure vessels

    International Nuclear Information System (INIS)

    Zipser, R.; Dose, G.F.

    1977-01-01

    The device makes possible periodical in-service inspections of welding seams and material of a reactor pressure vessel without local human presence. A 'support ring' encloses the pressure vessel in a horizontal plane with free space. It is vertically moved up and down in the space between pressure vessel and thermal shield by means of tackles. At a control desk placed in a protected area its movement is controlled and its vertical position is indicated. A 'rotating track' with its own drive is rotating remote-controlled on the 'support ring'. By a combination of the vertical with the rotating movement, an ultrasonic probe placed removably on the 'rotating hack', or a television camera will be brought to any position on the cylindrical circumference of the pressure vessel. Special devices extend the radius of action, in upward direction for inspecting the welding seams of the coolant nozzles, and in downward direction for the inspection of welds on the hemispherical bottom of the pressure vessel or on the outlet pipe nozzle placed there. The device remains installed during reactor operation, but is moved down to the lower horizontal surface of the thermal shield. Parts which are sensible to radiation like probes or television cameras and special devices will then be removed respectively mounted before beginning an inspection compaign. This position may be reached by the lower access in the biological shield and through an opening in the horizontal surface of the thermal shield. (HP) [de

  19. Water adsorption on TiO2 surfaces probed by soft X-ray spectroscopies: bulk materials vs. isolated nanoparticles

    Science.gov (United States)

    Benkoula, Safia; Sublemontier, Olivier; Patanen, Minna; Nicolas, Christophe; Sirotti, Fausto; Naitabdi, Ahmed; Gaie-Levrel, François; Antonsson, Egill; Aureau, Damien; Ouf, François-Xavier; Wada, Shin-Ichi; Etcheberry, Arnaud; Ueda, Kiyoshi; Miron, Catalin

    2015-01-01

    We describe an experimental method to probe the adsorption of water at the surface of isolated, substrate-free TiO2 nanoparticles (NPs) based on soft X-ray spectroscopy in the gas phase using synchrotron radiation. To understand the interfacial properties between water and TiO2 surface, a water shell was adsorbed at the surface of TiO2 NPs. We used two different ways to control the hydration level of the NPs: in the first scheme, initially solvated NPs were dried and in the second one, dry NPs generated thanks to a commercial aerosol generator were exposed to water vapor. XPS was used to identify the signature of the water layer shell on the surface of the free TiO2 NPs and made it possible to follow the evolution of their hydration state. The results obtained allow the establishment of a qualitative determination of isolated NPs’ surface states, as well as to unravel water adsorption mechanisms. This method appears to be a unique approach to investigate the interface between an isolated nano-object and a solvent over-layer, paving the way towards new investigation methods in heterogeneous catalysis on nanomaterials. PMID:26462615

  20. Lower-Cost, Relocatable Lunar Polar Lander and Lunar Surface Sample Return Probes

    Science.gov (United States)

    Amato, G. Michael; Garvin, James B.; Burt, I. Joseph; Karpati, Gabe

    2011-01-01

    Key science and exploration objectives of lunar robotic precursor missions can be achieved with the Lunar Explorer (LEx) low-cost, robotic surface mission concept described herein. Selected elements of the LEx concept can also be used to create a lunar surface sample return mission that we have called Boomerang

  1. Liquid-solid contact measurements using a surface thermocouple temperature probe in atmospheric pool boiling water

    International Nuclear Information System (INIS)

    Lee, L.Y.W.; Chen, J.C.; Nelson, R.A.

    1984-01-01

    Objective was to apply the technique of using a microthermocouple flush-mounted at the boiling surface for the measurement of the local-surface-temperature history in film and transition boiling on high temperature surfaces. From this measurement direct liquid-solid contact in film and transition boiling regimes was observed. In pool boiling of saturated, distilled, deionized water on an aluminum-coated copper surface, the time-averaged, local-liquid-contact fraction increased with decreasing surface superheat. Average contact duration increased monotonically with decreasing surface superheat, while frequency of liquid contact reached a maximum of approx. 50 contacts/s at a surface superheat of approx. 100 K and decreased gradually to 30 contacts/s near the critical heat flux. The liquid-solid contact duration distribution was dominated by short contacts 4 ms at low surface superheats, passing through a relatively flat contact duration distribution at about 80 0 K. Results of this paper indicate that liquid-solid contacts may be the dominant mechanism for energy transfer in the transition boiling process

  2. Uncertainty analysis of point by point sampling complex surfaces using touch probe CMMs

    DEFF Research Database (Denmark)

    Barini, Emanuele; Tosello, Guido; De Chiffre, Leonardo

    2007-01-01

    The paper describes a study concerning point by point scanning of complex surfaces using tactile CMMs. A four factors-two level full factorial experiment was carried out, involving measurements on a complex surface configuration item comprising a sphere, a cylinder and a cone, combined in a singl...

  3. Ag coated microneedle based surface enhanced Raman scattering probe for intradermal measurements

    Science.gov (United States)

    Yuen, Clement; Liu, Quan

    2013-06-01

    We propose a silver coated microneedle to detect test molecules, including R6G and glucose, positioned at a depth of more than 700 μm below a skin phantom surface for mimicking intradermal surface-enhanced Raman scattering measurements.

  4. PREFACE: Exploring surfaces and buried interfaces of functional materials by advanced x-ray and neutron techniques Exploring surfaces and buried interfaces of functional materials by advanced x-ray and neutron techniques

    Science.gov (United States)

    Sakurai, Kenji

    2010-12-01

    This special issue is devoted to describing recent applications of x-ray and neutron scattering techniques to the exploration of surfaces and buried interfaces of various functional materials. Unlike many other surface-sensitive methods, these techniques do not require ultra high vacuum, and therefore, a variety of real and complicated surfaces fall within the scope of analysis. It must be particularly emphasized that the techniques are capable of seeing even buried function interfaces as well as the surface. Furthermore, the information, which ranges from the atomic to mesoscopic scale, is highly quantitative and reproducible. The non-destructive nature of the techniques is another important advantage of using x-rays and neutrons, when compared with other atomic-scale analyses. This ensures that the same specimen can be measured by other techniques. Such features are fairly attractive when exploring multilayered materials with nanostructures (dots, tubes, wires, etc), which are finding applications in electronic, magnetic, optical and other devices. The Japan Applied Physics Society has established a group to develop the research field of studying buried function interfaces with x-rays and neutrons. As the methods can be applied to almost all types of materials, from semiconductor and electronic devices to soft materials, participants have fairly different backgrounds but share a common interest in state-of-the-art x-ray and neutron techniques and sophisticated applications. A series of workshops has been organized almost every year since 2001. Some international interactions have been continued intensively, although the community is part of a Japanese society. This special issue does not report the proceedings of the recent workshop, although all the authors are in some way involved in the activities of the above society. Initially, we intended to collect quite long overview papers, including the authors' latest and most important original results, as well as

  5. Probing the intrinsically oil-wet surfaces of pores in North Sea chalk at subpore resolution

    DEFF Research Database (Denmark)

    Hassenkam, Tue; Skovbjerg, Lone Lindbæk; Stipp, Susan Louise Svane

    2009-01-01

    been drilled in a water-bearing formation. At this site, the chalk has never seen oil, though at other locations, the same stratigraphic horizon with the same rock properties is known to be a productive oil reservoir. Thus the properties of the investigated particle surfaces are inherent to the chalk......Ultimate Oil recovery from chalk reservoirs is limited by many factors - including the grain size and the surface properties of the small mainly biogenic calcite particles that chalk is made off . Wettability, the tendency for water or oil to spread over a surface, of the particle surfaces is one...... of the controlling factors for the effectiveness of water flooding, one of the most common methods to improve oil recovery in Chalk reservoirs. Understanding surface wetting and its variability at scales smaller than the pore dimension will potentially provide clues for more effective oil production methods. We used...

  6. Measuring adhesion on rough surfaces using atomic force microscopy with a liquid probe

    Directory of Open Access Journals (Sweden)

    Juan V. Escobar

    2017-04-01

    Full Text Available We present a procedure to perform and interpret pull-off force measurements during the jump-off-contact process between a liquid drop and rough surfaces using a conventional atomic force microscope. In this method, a micrometric liquid mercury drop is attached to an AFM tipless cantilever to measure the force required to pull this drop off a rough surface. We test the method with two surfaces: a square array of nanometer-sized peaks commonly used for the determination of AFM tip sharpness and a multi-scaled rough diamond surface containing sub-micrometer protrusions. Measurements are carried out in a nitrogen atmosphere to avoid water capillary interactions. We obtain information about the average force of adhesion between a single peak or protrusion and the liquid drop. This procedure could provide useful microscopic information to improve our understanding of wetting phenomena on rough surfaces.

  7. Small-angle neutron scattering study of recombinant yeast-derived human hepatitis B virus surface antigen vaccine particle

    Science.gov (United States)

    Sato, M.; Ito, Y.; Kameyama, K.; Imai, M.; Ishikawa, N.; Takagi, T.

    1995-02-01

    The overall and internal structure of recombinant yeast-derived human hepatitis B virus surface antigen vaccine particles was investigated by small-angle neutron scattering using the contrast variation method. The vaccine is a nearly spherical particle, and its contrast-matching point was determined to be at about 24% D 2O content, indicating that a large part of the vaccine particle is occupied by lipids and carbohydrates from the yeast. The Stuhrmann plot suggests that the surface antigens exist predominantly in the peripheral region of the particle, which is favorable to the induction of anti-virus antibodies.

  8. Symmetry energy and surface properties of neutron-rich exotic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gaidarov, M. K.; Antonov, A. N. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784 (Bulgaria); Sarriguren, P. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Moya de Guerra, E. [Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    2014-07-23

    The symmetry energy, the neutron pressure and the asymmetric compressibility of spherical Ni, Sn, and Pb and deformed Kr and Sm neutron-rich even-even nuclei are calculated within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated for isotopic chains of these nuclei in the framework of the deformed self-consistent mean-field Skyrme HF+BCS method. The mass dependence of the nuclear symmetry energy and the neutron skin thickness are also studied together with the role of the neutron-proton asymmetry. The studied correlations reveal a smoother behavior in the case of spherical nuclei than for deformed ones. We also notice that the neutron skin thickness obtained for {sup 208}Pb with SLy4 force is found to be in a good agreement with the recent data. In addition to the interest that this study may have by itself, we give some numerical arguments in proof of the existence of peculiarities of the studied quantities in Ni and Sn isotopic chains that are not present in the Pb chain.

  9. Scanning probe studies of water nucleation on aluminum oxide and gold surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Missert, N. [Sandia National Laboratories, Albuquerque, NM 87185-1415 (United States)], E-mail: namisse@sandia.gov; Copeland, R.G. [Sandia National Laboratories, Albuquerque, NM 87185-1415 (United States)

    2008-01-30

    The nucleation of nanoscale water at surfaces in humid environments is sensitive to several factors, including the details of the surface morphology, ability of the surface to hydrate and the presence of contaminants. Tapping mode atomic force microscopy was used to investigate the nucleation process as a function of relative humidity (RH) on passive aluminum and gold thin films. Films exposed to the ambient environment prior to RH exposure showed discrete structures with lateral sizes ranging from 10 to 100 nm only at RH > 70%. These structures formed preferentially at grain boundaries, triple points and regions with significant topography such as protruding grains. The morphology of the passive aluminum surface is permanently altered at the sites where discrete structures were observed; nodules with heights ranging from 0.5 to 2 nm persist even after reducing the RH to <2%. The gold surface does not show such a permanent change in morphology after reducing the RH. Passive aluminum films exposed to high RH immediately after growth (e.g. no ambient exposure) do not show discrete structures even at the highest RH exposures of 90%, suggesting a hydrophilic surface and the importance of surface hydrocarbon contaminants in affecting the distribution of the water layer.

  10. Scanning probe studies of water nucleation on aluminum oxide and gold surfaces

    International Nuclear Information System (INIS)

    Missert, N.; Copeland, R.G.

    2008-01-01

    The nucleation of nanoscale water at surfaces in humid environments is sensitive to several factors, including the details of the surface morphology, ability of the surface to hydrate and the presence of contaminants. Tapping mode atomic force microscopy was used to investigate the nucleation process as a function of relative humidity (RH) on passive aluminum and gold thin films. Films exposed to the ambient environment prior to RH exposure showed discrete structures with lateral sizes ranging from 10 to 100 nm only at RH > 70%. These structures formed preferentially at grain boundaries, triple points and regions with significant topography such as protruding grains. The morphology of the passive aluminum surface is permanently altered at the sites where discrete structures were observed; nodules with heights ranging from 0.5 to 2 nm persist even after reducing the RH to <2%. The gold surface does not show such a permanent change in morphology after reducing the RH. Passive aluminum films exposed to high RH immediately after growth (e.g. no ambient exposure) do not show discrete structures even at the highest RH exposures of 90%, suggesting a hydrophilic surface and the importance of surface hydrocarbon contaminants in affecting the distribution of the water layer

  11. Structural properties of oligonucleotide monolayers on gold surfaces probed by fluorescence investigations.

    Science.gov (United States)

    Rant, Ulrich; Arinaga, Kenji; Fujita, Shozo; Yokoyama, Naoki; Abstreiter, Gerhard; Tornow, Marc

    2004-11-09

    We present optical investigations on the conformation of oligonucleotide layers on Au surfaces. Our studies concentrate on the effect of varying surface coverage densities on the structural properties of layers of 12- and 24mer single-stranded DNA, tethered to the Au surface at one end while being labeled with a fluorescent marker at the opposing end. The distance-dependent energy transfer from the marker dye to the metal surface, which causes quenching of the observed fluorescence, is used to provide information on the orientation of the DNA strands relative to the surface. Variations in the oligonucleotide coverage density, as determined from electrochemical quantification, over 2 orders of magnitude are achieved by employing different preparation conditions. The observed enhancement in fluorescence intensity with increasing DNA coverage can be related to a model involving mutual steric interactions of oligonucleotides on the surface, as well as fluorescence quenching theory. Finally, the applicability of the presented concepts for investigations of heterogeneous monolayers is demonstrated by means of studying the coadsorption of mercaptohexanol onto DNA-modified Au surfaces.

  12. Neutron detector

    Science.gov (United States)

    Stephan, Andrew C [Knoxville, TN; Jardret,; Vincent, D [Powell, TN

    2011-04-05

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  13. Ultralow surface recombination velocity in InP nanowires probed by terahertz spectroscopy.

    Science.gov (United States)

    Joyce, Hannah J; Wong-Leung, Jennifer; Yong, Chaw-Keong; Docherty, Callum J; Paiman, Suriati; Gao, Qiang; Tan, H Hoe; Jagadish, Chennupati; Lloyd-Hughes, James; Herz, Laura M; Johnston, Michael B

    2012-10-10

    Using transient terahertz photoconductivity measurements, we have made noncontact, room temperature measurements of the ultrafast charge carrier dynamics in InP nanowires. InP nanowires exhibited a very long photoconductivity lifetime of over 1 ns, and carrier lifetimes were remarkably insensitive to surface states despite the large nanowire surface area-to-volume ratio. An exceptionally low surface recombination velocity (170 cm/s) was recorded at room temperature. These results suggest that InP nanowires are prime candidates for optoelectronic devices, particularly photovoltaic devices, without the need for surface passivation. We found that the carrier mobility is not limited by nanowire diameter but is strongly limited by the presence of planar crystallographic defects such as stacking faults in these predominantly wurtzite nanowires. These findings show the great potential of very narrow InP nanowires for electronic devices but indicate that improvements in the crystallographic uniformity of InP nanowires will be critical for future nanowire device engineering.

  14. Precision Hopping/Rolling Robotic Surface Probe Based on Tensegrity Structures

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to overcome the limitations of wheeled surface rovers by combining recent advances in ball-shaped soft-robots based on tensegrity structures (a tension...

  15. Theoretical atomic-force-microscopy study of a stepped surface: Nonlocal effects in the probe

    International Nuclear Information System (INIS)

    Girard, C.

    1991-01-01

    The interaction force between a metallic tip and a nonplanar dielectric surface is derived from a nonlocal formalism. A general formulation is given for the case of a spherical tip of nanometer size and for surfaces of arbitrary shapes (stepped surfaces and single crystals adsorbed on a planar surface). The dispersion part of the attractive force is obtained from a nonlocal theory expressed in terms of generalized electric susceptibilities of the two constituents. Implications for atomic force microscopy in attractive modes are discussed. In this context, the present model indicates two different forms of corrugation: those due to the protuberance present on the tip leading to atomic corrugations; nanometer-sized corrugations detected in the attractive region by the spherical part of the tip

  16. Nitrate as a probe of cytochrome c surface: crystallographic identification of crucial "hot spots" for protein-protein recognition.

    Science.gov (United States)

    De March, Matteo; Demitri, Nicola; De Zorzi, Rita; Casini, Angela; Gabbiani, Chiara; Guerri, Annalisa; Messori, Luigi; Geremia, Silvano

    2014-06-01

    The electrostatic surface of cytochrome c and its changes with the iron oxidation state are involved in the docking and undocking processes of this protein to its biological partners in the mitochondrial respiratory pathway. To investigate the subtle mechanisms of formation of productive macromolecular complexes and of their breakage following the electron transfer process, the X-ray structures of horse heart ferri-cytochrome c (trigonal form) and ferro-cytochrome c (monoclinic form) were obtained using nitrate ions both as a crystallizing agent and an anionic probe for mapping the electrostatic surface changes. Both crystal forms contain three protein molecules in the asymmetric unit. In addition, a total of 21.5 and 18 crystallographically independent nitrate ions were identified for the trigonal and monoclinic forms, respectively. By matching all the six crystallographically independent protein molecules, 26 different anion-protein interaction sites were identified on the surfaces of cytochrome c, 10 of which were found in both forms, 8 present only in the oxidized and 8 only in the reduced form. The structural analysis of the electron transfer complexes, based on this new information, suggests a specific exit strategy for cytochrome c after formation of productive protein-protein complexes: a directional sliding mechanism for the electron shuttle on the surface of the redox partner is proposed to take place after the electron transfer process has occurred. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Workshop on Probing Frontiers in Matter with Neutron Scattering, Wrap-up Session Chaired by John C. Browne on December 14, 1997, at Fuller Lodge, Los Alamos, New Mexico

    International Nuclear Information System (INIS)

    Mezei, F.; Thompson, J.

    1998-01-01

    The Workshop on Probing Frontiers in Matter with Neutron Scattering consisted of a series of lectures and discussions about recent highlights in neutron scattering. In this report, we present the transcript of the concluding discussion session (wrap-up session) chaired by John C. Browne, Director of Los Alamos National Laboratory. The workshop had covered a spectrum of topics ranging from high T c superconductivity to polymer science, from glasses to molecular biology, a broad review aimed at identifying trends and future needs in condensed matter research. The focus of the wrap-up session was to summarize the workshop participants' views on developments to come. Most of the highlights presented during the workshop were the result of experiments performed at the leading reactor-based neutron scattering facilities. However, recent advances with very high power accelerators open up opportunities to develop new approaches to spallation technique that could decisively advance neutron scattering research in areas for which reactor sources are today by far the best choice. The powerful combination of neutron scattering and increasingly accurate computer modeling emerged as another area of opportunity for research in the coming decades

  18. Workshop on Probing Frontiers in Matter with Neutron Scattering, Wrap-up Session Chaired by John C. Browne on December 14, 1997, at Fuller Lodge, Los Alamos, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Mezei, F.; Thompson, J.

    1998-12-01

    The Workshop on Probing Frontiers in Matter with Neutron Scattering consisted of a series of lectures and discussions about recent highlights in neutron scattering. In this report, we present the transcript of the concluding discussion session (wrap-up session) chaired by John C. Browne, Director of Los Alamos National Laboratory. The workshop had covered a spectrum of topics ranging from high T{sub c} superconductivity to polymer science, from glasses to molecular biology, a broad review aimed at identifying trends and future needs in condensed matter research. The focus of the wrap-up session was to summarize the workshop participants' views on developments to come. Most of the highlights presented during the workshop were the result of experiments performed at the leading reactor-based neutron scattering facilities. However, recent advances with very high power accelerators open up opportunities to develop new approaches to spallation technique that could decisively advance neutron scattering research in areas for which reactor sources are today by far the best choice. The powerful combination of neutron scattering and increasingly accurate computer modeling emerged as another area of opportunity for research in the coming decades.

  19. Probing Surface-Adlayer Conjugation on Organic-Modified Si(111) Surfaces with Microscopy, Scattering, Spectroscopy, and Density Functional Theory

    International Nuclear Information System (INIS)

    Kellar, Joshua A.; Lin, Jui-Ching; Kim, Jun-Hyun; Yoder, Nathan L.; Bevan, Kirk H.; Stokes, Grace Y.; Geiger, Franz M.; Nguyen, SonBinh T.; Bedzyk, Michael J.; Hersam, Mark C.

    2009-01-01

    Highly conjugated molecules bound to silicon are promising candidates for organosilicon electronic devices and sensors. In this study, 1-bromo-4-ethynylbenzene was synthesized and reacted with a hydrogen-passivated Si(111) surface via ultraviolet irradiation. Through an array of characterization and modeling tools, the binding configuration and morphology of the reacted molecule were thoroughly analyzed. Atomic force microscopy confirmed an atomically flat surface morphology following reaction, while X-ray photoelectron spectroscopy verified reaction to the surface via the terminal alkyne moiety. In addition, synchrotron X-ray characterization, including X-ray reflectivity, X-ray fluorescence, and X-ray standing wave measurements, enabled sub-angstrom determination of the position of the bromine atom with respect to the silicon lattice. This structural characterization was quantitatively compared with density functional theory (DFT) calculations, thus enabling the π-conjugation of the terminal carbon atoms to be deduced. The X-ray and DFT results were additionally corroborated with the vibrational spectrum of the organic adlayer, which was measured with sum frequency generation. Overall, these results illustrate that the terminal carbon atoms in 1-bromo-4-ethynylbenzene adlayers on Si(111) retain π-conjugation, thus revealing alkyne molecules as promising candidates for organosilicon electronics and sensing.

  20. Relaxation of excited surface states of thin Ge-implanted silica films probed by OSEE spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zatsepin, A.F., E-mail: a.f.zatsepin@urfu.ru [Ural Federal University, Mira Street 19, 620002 Ekaterinburg (Russian Federation); Buntov, E.A.; Mikhailovich, A.P.; Slesarev, A.I. [Ural Federal University, Mira Street 19, 620002 Ekaterinburg (Russian Federation); Schmidt, B. [Research Center Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, P.O. Box 510119, D-01314 Dresden (Germany); Czarnowski, A. von; Fitting, Hans-Joachim [Institute of Physics, University of Rostock, Universitätsplatz 3, D-18051 Rostock (Germany)

    2016-01-15

    As an example of thin silica films, 30 nm SiO{sub 2}–Si heterostructures implanted with Ge{sup +} ions (10{sup 16} cm{sup −2} fluence) and rapid thermally annealed (RTA) at 950 °C are studied by means of optically stimulated electron emission (OSEE) in the spectral region of optical transparency for bulk silica. Quartz glass samples were used as references. Experimental data revealed a strong dependence between electron emission spectral features and RTA annealing time. The spectral contributions of both surface band tail states and interband transitions were clearly distinguished. The application of emission Urbach rule as well as Kane and Pässler equations allowed to analyze the OSEE spectra at different optical excitation energy ranges and to retrieve the important microstructural and energy parameters. The observed correlations between parameter values of Urbach- and Kane-related models suggest the implantation-induced conversion of both the vibrational subsystem and energy band of surface and interface electronic states. - Highlights: • Peculiarities of electron emission from excited surface states of SiO{sub 2}:Ge structures are studied. • Spectral contributions of surface band tails and interband transitions are distinguished. • Urbach and Kane models allow to examine photo-thermal emission mechanism. • Surface energy gap and structural disorder parameters are determined.

  1. Probing spin helical surface states in topological HgTe nanowires

    Science.gov (United States)

    Ziegler, J.; Kozlovsky, R.; Gorini, C.; Liu, M.-H.; Weishäupl, S.; Maier, H.; Fischer, R.; Kozlov, D. A.; Kvon, Z. D.; Mikhailov, N.; Dvoretsky, S. A.; Richter, K.; Weiss, D.

    2018-01-01

    Nanowires with helical surface states represent key prerequisites for observing and exploiting phase-coherent topological conductance phenomena, such as spin-momentum locked quantum transport or topological superconductivity. We demonstrate in a joint experimental and theoretical study that gated nanowires fabricated from high-mobility strained HgTe, known as a bulk topological insulator, indeed preserve the topological nature of the surface states, that moreover extend phase-coherently across the entire wire geometry. The phase-coherence lengths are enhanced up to 5 μ m when tuning the wires into the bulk gap, so as to single out topological transport. The nanowires exhibit distinct conductance oscillations, both as a function of the flux due to an axial magnetic field and of a gate voltage. The observed h /e -periodic Aharonov-Bohm-type modulations indicate surface-mediated quasiballistic transport. Furthermore, an in-depth analysis of the scaling of the observed gate-dependent conductance oscillations reveals the topological nature of these surface states. To this end we combined numerical tight-binding calculations of the quantum magnetoconductance with simulations of the electrostatics, accounting for the gate-induced inhomogeneous charge carrier densities around the wires. We find that helical transport prevails even for strongly inhomogeneous gating and is governed by flux-sensitive high-angular momentum surface states that extend around the entire wire circumference.

  2. Quantum state-resolved gas/surface reaction dynamics probed by reflection absorption infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chen Li [Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Goettingen (Germany); Ueta, Hirokazu; Beck, Rainer D. [Laboratoire de Chimie Physique Moleculaire, Ecole Polytechnique Federale de Lausanne (Switzerland); Bisson, Regis [Aix-Marseille Universite, PIIM, CNRS, UMR 7345, 13397 Marseille (France)

    2013-05-15

    We report the design and characterization of a new molecular-beam/surface-science apparatus for quantum state-resolved studies of gas/surface reaction dynamics combining optical state-specific reactant preparation in a molecular beam by rapid adiabatic passage with detection of surface-bound reaction products by reflection absorption infrared spectroscopy (RAIRS). RAIRS is a non-invasive infrared spectroscopic detection technique that enables online monitoring of the buildup of reaction products on the target surface during reactant deposition by a molecular beam. The product uptake rate obtained by calibrated RAIRS detection yields the coverage dependent state-resolved reaction probability S({theta}). Furthermore, the infrared absorption spectra of the adsorbed products obtained by the RAIRS technique provide structural information, which help to identify nascent reaction products, investigate reaction pathways, and determine branching ratios for different pathways of a chemisorption reaction. Measurements of the dissociative chemisorption of methane on Pt(111) with this new apparatus are presented to illustrate the utility of RAIRS detection for highly detailed studies of chemical reactions at the gas/surface interface.

  3. Comparison of neutron scattering and DFM capacitance instruments ...

    African Journals Online (AJOL)

    Soil water evaporation is an important parameter that needs to be accurately measured for the design of water-efficient agricultural systems. With this study, the abilities of the DFM capacitance probes and a neutron water meter (NWM) to measure evaporation from the soil surface were compared. Measured evaporation was ...

  4. Reactions on catalytic probe surface during oxygen plasma treatment of polyether sulphone: Reakcije na površini katalitične sonde med plazemsko obdelavo polieter sulfona:

    OpenAIRE

    Mozetič, Miran

    1998-01-01

    Experiments on the behavior of a nickel catalytic probe during activation of the surface of polyether sulphone in oxygen plasma are described. The temperature of the probe mounted 30 cm apart from inductively coupled RF oxygen plasma was measured for the case of empty dischaarge vessel and the case a sample with the dimensions of 8 cm x 1.2 cm x 0.4 cm was mounted in the middle of the discharge coil. It was found that both the maximum temperature and the first time derivative of the probe was...

  5. Contribution of the surface contamination of uranium-materials on the quantitative analysis results by electron probe microbeam analysis

    International Nuclear Information System (INIS)

    Bonino, O.; Fournier, C.; Fucili, C.; Dugne, O.; Merlet, C.

    2000-01-01

    The analytical testing of uranium materials is necessary for quality research and development in nuclear industry applications (enrichment, safety studies, fuel, etc). Electron Probe Microbeam Analysis Wavelength Dispersive Spectrometry (EPMA-WDS) is a dependable non-destructive analytical technology. The characteristic X-ray signal is measured to identify and quantify the sample components, and the analyzed volume is about one micron cube. The surface contamination of uranium materials modifies and contributes to the quantitative analysis results of EPMA-WDS. This contribution is not representative of the bulk. A thin oxidized layer appears in the first instants after preparation (burnishing, cleaning) as well as a carbon contamination layer, due to metallographic preparation and carbon cracking under the impact of the electron probe. Several analytical difficulties subsequently arise, including an overlapping line between the carbon Ka ray and the Uranium U NIVOVI ray. Sensitivity and accuracy of the quantification of light elements like carbon and oxygen are also reduced by the presence of uranium. The aim of this study was to improve the accuracy of quantitative analysis on uranium materials by EPMA-WDS by taking account of the contribution of surface contamination. The first part of this paper is devoted to the study of the contaminated surface of the uranium materials U, UFe 2 and U 6 Fe a few hours after preparation. These oxidation conditions are selected so as to reproduce the same contamination surfaces occurring in microprobe analytical conditions. Surface characterization techniques were SIMS and Auger spectroscopy. The contaminated surfaces are shown. They consist of successive layers: a carbon layer, an oxidized iron layer, followed by an iron depletion layer (only in UFe 2 and U 6 Fe), and a ternary oxide layer (U-Fe-O for UFe 2 et U 6 Fe and UO 2+x for uranium). The second part of the paper addresses the estimation of the errors in quantitative

  6. Probing adsorption phenomena on a single crystal Pt-alloy surface under oxygen reduction reaction conditions

    International Nuclear Information System (INIS)

    Bondarenko, Alexander S.; Stephens, Ifan E.L.; Bech, Lone; Chorkendorff, Ib

    2012-01-01

    Highlights: ► Impedance spectroscopy of Cu/Pt(1 1 1) near-surface alloy and Pt(1 1 1). ► Presence of oxygen changes little the adsorption dynamics. ► Adsorption dynamics similar on alloy and Pt(1 1 1). ► Electrosorption phenomena on alloy shifted in potential, relative to Pt(1 1 1). - Abstract: The adsorption dynamics of *OH and *O species at Pt(1 1 1) and Cu/Pt(1 1 1) near-surface alloy (NSA) surfaces in oxygen-free and O 2 -saturated 0.1 M HClO 4 was investigated. Subsurface Cu modifies the electronic structure at the Pt(1 1 1) surface resulting in weaker bonding to adsorbates like *OH, *H or *O. This provides a basis for the high oxygen reduction activity of the NSA, as predicted by density functional theory calculations. The shift in *OH adsorption of around 0.16 V towards more positive potentials can be clearly monitored in absence of O 2 and under the oxygen reduction reaction (ORR) conditions for the Cu/Pt(1 1 1) NSA. In both cases, for Pt(1 1 1) and NSA, the *OH(*O) adsorption dynamics is very similar in the absence of oxygen and under ORR conditions. Therefore, theoretical assumptions about the coverage of adsorbates in the absence of oxygen can be reasonably extrapolated to the situation when oxygen reduction takes place at the surface. A ∼5-fold improvement in the ORR activity over the Pt(1 1 1) at 0.9 V (RHE) was measured for the Cu/Pt(1 1 1) near-surface alloy.

  7. Surface-Enhanced Raman Scattering Sensor on an Optical Fiber Probe Fabricated with a Femtosecond Laser

    OpenAIRE

    Ma, Xiaodong; Huo, Haibin; Wang, Wenhui; Tian, Ye; Wu, Nan; Guthy, Charles; Shen, Mengyan; Wang, Xingwei

    2010-01-01

    A novel fabrication method for surface-enhanced Raman scattering (SERS) sensors that used a fast femtosecond (fs) laser scanning process to etch uniform patterns and structures on the endface of a fused silica optical fiber, which is then coated with a thin layer of silver through thermal evaporation is presented. A high quality SERS signal was detected on the patterned surface using a Rhodamine 6G (Rh6G) solution. The uniform SERS sensor built on the tip of the optical fiber tip was small, l...

  8. CO2 sorption on surface-modified carbonaceous support: Probing the influence of the carbon black microporosity and surface polarity

    International Nuclear Information System (INIS)

    Gargiulo, Valentina; Alfè, Michela; Ammendola, Paola; Raganati, Federica; Chirone, Riccardo

    2016-01-01

    Graphical abstract: - Highlights: • CO 2 -sorbent materials preparation by surface modification of CB. • CB functionalization (amino-groups), CB coating (Fe 3 O 4 ), CB impregnation (ionic liquid). • Sorbents bearing basic functionalities exhibit the higher CO 2 sorption capacity. • Microporous supporting material limits the CO 2 accessibility toward the adsorbing material. - Abstract: The use of solid sorbents is a convenient option in post-combustion CO 2 capture strategies. Sorbents selection is a key point because the materials are required to be both low-cost and versatile in typical post-combustion conditions in order to guarantee an economically advantageous overall process. This work compares strategies to tailor the chemico-physical features of carbon black (CB) by surface-modification and/or coating with a CO 2 -sorbent phase. The influence of the CB microporosity, enhanced by chemical/thermal treatments, is also taken into account. Three CB surface modifications are performed and compared: (i) oxidation and functionalization with amino-groups, (ii) coating with iron oxides and (iii) impregnation with an ionic liquid (IL). The CO 2 capture performance is evaluated on the basis of the breakthrough curves measured at atmospheric pressure and room temperature in a lab-scale fixed bed micro-reactor. Most of tested solids adsorb a CO 2 amount significantly higher than a 13X zeolite and DARCO FGD (Norit) activated carbon (up to 4 times more in the best case). The sorbents bearing basic functionalities (amino-groups and IL) exhibit the highest CO 2 sorption capacity. The use of a microporous carbonaceous support limits the accessibility of CO 2 toward the adsorbing phase (IL or FM) lowering the number of accessible binding sites for CO 2 .

  9. Measurement of the lunar neutron density profile

    International Nuclear Information System (INIS)

    Woolum, D.S.; Burnett, D.S.; Furst, M.; Weiss, J.R.

    1975-01-01

    An in situ measurement of the lunar neutron density from 20 to 400 g cm -2 depth below the lunar surface was made by the Apollo 17 Lunar Neutron Probe Experiment (LNPE) using particle tracks produced by the 10 B (n,α) 7 Li reaction. Both the absolute magnitude and the depth profile of the neutron density are in good agreement with theoretical calculations by Lingenfelter, Canfield, and Hampel. However, relatively small deviations between experiment and theory in the effect of Cd absorption on the neutron density and in the relative 149 Sm to 157 Gd capture rates reported previously (Russ et al., 1972) imply that the true lunar 157 Gd capture rate is about one half of that calculated theoretically. (Auth.)

  10. Ultrasensitive probing of the protein resistance of PEG surfaces by secondary ion mass spectrometry

    DEFF Research Database (Denmark)

    Kingshott, P.; McArthur, S.; Thissen, H.

    2002-01-01

    The highly sensitive surface analytical techniques X-ray photoelectron spectroscopy (XPS) and time-of-flight static secondary ion mass spectrometry (ToF-SIMS) were used to test the resistance of poly(ethylene glycol) (PEG) coatings towards adsorption of lysozyme (LYS) and fibronectin (FN). PEG co...

  11. Probing the Active Surface Sites for CO Reduction on Oxide-Derived Copper Electrocatalysts

    DEFF Research Database (Denmark)

    Verdaguer Casadevall, Arnau; Li, Christina W.; Johansson, Tobias Peter

    2015-01-01

    CO electroreduction activity on oxide-derived Cu (OD-Cu) was found to correlate with metastable surface features that bind CO strongly. OD-Cu electrodes prepared by H-2 reduction of Cu2O precursors reduce CO to acetate and ethanol with nearly 50% Faradaic efficiency at moderate overpotential. Tem...

  12. Probing Earth’s conductivity structure beneath oceans by scalar geomagnetic data: autonomous surface vehicle solution

    DEFF Research Database (Denmark)

    Kuvshinov, Alexey; Matzka, Jürgen; Poedjono, Benny

    2016-01-01

    to the conductivity structure beneath the ocean. We conclude that the sensitivity, depending on the bathymetry gradient, is typically largest near the coast offshore. We show that such sea-surface marine induction surveys can be performed with the Wave Glider, an easy-to-deploy, autonomous, energy-harvesting floating...

  13. Electrophoresis in ice surface grooves for probing protein affinity to a specific plane of ice crystal.

    Science.gov (United States)

    Inagawa, Arinori; Okada, Yusuke; Okada, Tetsuo

    2018-06-01

    Channel-like grooves are formed on the surface of frozen aqueous sucrose. They are filled with a freeze concentrated solution (FCS) and act as an efficient size-tunable separation field for micro and nanoparticles. The width of the channel can be easily varied by changing the temperature. Because the channel width decreases with decreasing temperature, particles become immobilized due to physical interference from the ice wall when the temperature reaches a threshold point specific to the particle size. Surface modification of particles can add a factor of chemical interaction between the particles and ice walls. In this study, anti-freeze proteins (AFPs) are anchored on 1µm-polystyrene (PS) particles, and their behavior in the surface grooves on the ice is studied. The threshold temperature is an effective criterion for evaluating chemical interactions between particles and ice walls. The AFP binding on 1µm PS particles lowers the threshold temperature by 2.5°C, indicating interactions between AFPs on the PS particles and the ice wall. Because the AFPs studied here show selectivity towards the prism plane, it is critical that the prism plane of the ice crystal is in contact with the FCS in the surface grooves. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Possibilities of using neutron activation analysis to discovery antimony aureoles at near-surface deposits

    International Nuclear Information System (INIS)

    Voin, M.I.; Kuligin, V.M.; Rakovskij, Eh.E.

    1978-01-01

    Described is the technique for determining antimony in rock and ore samples by instrumental neutron activation method with the sensitivity of 0.5 g/t from the 0.3-0.5 g weighed amount. Antimony was determined using the photopeak of antimony-124 isotope with the energy of 1692 keV. For analysis, 0.1 g samples were packed in aluminium foil and irradiated for 22 hours by reactor neutron fluence of 1.2x10 13 neutron/cm 2 xs. After cooling for 7 days induced activity of samples was measured using multichannel analizer with semiconductor detector with sensitive zone volume of 40 cm 3 . Real sensitivity while determining antimony was 1g/t, mean square error in the content range of 1-10 g/t is 14%

  15. Model Atmospheres for X-ray Bursting Neutron Stars

    OpenAIRE

    Medin, Zach; von Steinkirch, Marina; Calder, Alan C.; Fontes, Christopher J.; Fryer, Chris L.; Hungerford, Aimee L.

    2016-01-01

    The hydrogen and helium accreted by X-ray bursting neutron stars is periodically consumed in runaway thermonuclear reactions that cause the entire surface to glow brightly in X-rays for a few seconds. With models of the emission, the mass and radius of the neutron star can be inferred from the observations. By simultaneously probing neutron star masses and radii, X-ray bursts are one of the strongest diagnostics of the nature of matter at extremely high densities. Accurate determinations of t...

  16. Scaling of the Surface Plasmon Resonance in Gold and Silver Dimers Probed by EELS

    DEFF Research Database (Denmark)

    Kadkhodazadeh, Shima; de Lasson, Jakob Rosenkrantz; Beleggia, Marco

    2014-01-01

    The dependence of surface plasmon coupling on the distance between two nanoparticles (dimer) is the basis of nanometrology tools such as plasmon rulers. Application of these nanometric rulers requires an accurate description of the scaling of the surface plasmon resonance (SPR) wavelength...... with distance. Here, we have applied electron energy-loss spectroscopy (EELS) and scanning transmission electron microscopy (STEM) imaging to investigate the relationship between the SPR wavelength of gold and silver nanosphere dimers (radius R) and interparticle distance (d) in the range 0.1R .... Instead, within the range 0.1R gold and silver dimers. Despite this common power dependence, consistently larger SPR wavelength shifts are registered for silver for a given change in d, implying...

  17. EVIDENCE FOR DCO+ AS A PROBE OF IONIZATION IN THE WARM DISK SURFACE

    International Nuclear Information System (INIS)

    Favre, Cécile; Bergin, Edwin A.; Cleeves, L. Ilsedore; Hersant, Franck; Qi, Chunhua; Aikawa, Yuri

    2015-01-01

    In this Letter, we model the chemistry of DCO + in protoplanetary disks. We find that the overall distribution of the DCO + abundance is qualitatively similar to that of CO but is dominated by a thin layer located at the inner disk surface. To understand its distribution, we investigate the different key gas-phase deuteration pathways that can lead to the formation of DCO + . Our analysis shows that the recent update in the exothermicity of the reaction involving CH 2 D + as a parent molecule of DCO + favors deuterium fractionation in warmer conditions. As a result, the formation of DCO + is enhanced in the inner warm surface layers of the disk where X-ray ionization occurs. Our analysis points out that DCO + is not a reliable tracer of the CO snow line as previously suggested. We thus predict that DCO + is a tracer of active deuterium and, in particular, X-ray ionization of the inner disk

  18. Positronic probe of vacancy defects on surfaces of Au nanoparticles embedded in MgO

    International Nuclear Information System (INIS)

    Xu, Jun; Moxom, J.; Somieski, B.; White, C. W.; Mills, A. P.; Suzuki, R.; Ishibashi, S.

    2001-01-01

    Clusters of four atomic vacancies were found in Au nanoparticle-embedded MgO by positron lifetime spectroscopy [Phys. Rev. Lett. 83, 4586 (1999)]. These clusters were also suggested to locate at the surface of Au nanoparticles by one-detector measurements of Doppler broadening of annihilation radiation. In this work we provide evidence, using two-detector coincidence experiments of Doppler broadening (2D-DBAR), to clarify that these vacancy clusters reside on the surfaces of Au nanoparticles. This work also demonstrates a method for identifying defects at nanomaterials interfaces: a combination of both positron lifetime spectroscopy, which tells the type of the defects, and 2D-DBAR measurements, which reveals chemical environment of the defects

  19. Positronic probe of vacancy defects on surfaces of Au nanoparticles embedded in MgO

    Science.gov (United States)

    Xu, Jun; Moxom, J.; Somieski, B.; White, C. W.; Mills, A. P., Jr.; Suzuki, R.; Ishibashi, S.

    2001-09-01

    Clusters of four atomic vacancies were found in Au nanoparticle-embedded MgO by positron lifetime spectroscopy [Phys. Rev. Lett. 83, 4586 (1999)]. These clusters were also suggested to locate at the surface of Au nanoparticles by one-detector measurements of Doppler broadening of annihilation radiation. In this work we provide evidence, using two-detector coincidence experiments of Doppler broadening (2D-DBAR), to clarify that these vacancy clusters reside on the surfaces of Au nanoparticles. This work also demonstrates a method for identifying defects at nanomaterials interfaces: a combination of both positron lifetime spectroscopy, which tells the type of the defects, and 2D-DBAR measurements, which reveals chemical environment of the defects.

  20. Effect of the interaction conditions of the probe of an atomic-force microscope with the n-GaAs surface on the triboelectrization phenomenon

    Energy Technology Data Exchange (ETDEWEB)

    Baklanov, A. V., E-mail: baklanov@mail.ioffe.ru [St. Petersburg State Polytechnical University, Institute of Physics, Nanotechnology, and Telecommunications (Russian Federation); Gutkin, A. A.; Kalyuzhnyy, N. A. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Brunkov, P. N. [St. Petersburg State Polytechnical University, Institute of Physics, Nanotechnology, and Telecommunications (Russian Federation)

    2015-08-15

    Triboelectrization as a result of the scanning of an atomic-force-microscope probe over an n-GaAs surface in the contact mode is investigated. The dependences of the local potential variation on the scanning rate and the pressing force of the probe are obtained. The results are explained by point-defect formation in the surface layers of samples under the effect of deformation of these layers during probe scanning. The charge localized at these defects in the case of equilibrium changes the potential of surface, which is subject to triboelectrization. It is shown that, for qualitative explanation of the observed dependences, it is necessary to take into account both the generation and annihilation of defects in the region experiencing deformation.

  1. Endoscopic add-on stiffness probe for real-time soft surface characterisation in MIS.

    Science.gov (United States)

    Faragasso, A; Stilli, A; Bimbo, J; Noh, Y; Liu, H; Nanayakkara, T; Dasgupta, P; Wurdemann, H A; Althoefer, K

    2014-01-01

    This paper explores a novel stiffness sensor which is mounted on the tip of a laparoscopic camera. The proposed device is able to compute stiffness when interacting with soft surfaces. The sensor can be used in Minimally Invasive Surgery, for instance, to localise tumor tissue which commonly has a higher stiffness when compared to healthy tissue. The purely mechanical sensor structure utilizes the functionality of an endoscopic camera to the maximum by visually analyzing the behavior of trackers within the field of view. Two pairs of spheres (used as easily identifiable features in the camera images) are connected to two springs with known but different spring constants. Four individual indenters attached to the spheres are used to palpate the surface. During palpation, the spheres move linearly towards the objective lens (i.e. the distance between lens and spheres is changing) resulting in variations of their diameters in the camera images. Relating the measured diameters to the different spring constants, a developed mathematical model is able to determine the surface stiffness in real-time. Tests were performed using a surgical endoscope to palpate silicon phantoms presenting different stiffness. Results show that the accuracy of the sensing system developed increases with the softness of the examined tissue.

  2. Probing hot-electron effects in wide area plasmonic surfaces using X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ayas, Sencer; Cupallari, Andi; Dana, Aykutlu, E-mail: aykutlu@unam.bilkent.edu.tr [UNAM Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey)

    2014-12-01

    Plasmon enhanced hot carrier formation in metallic nanostructures increasingly attracts attention due to potential applications in photodetection, photocatalysis, and solar energy conversion. Here, hot-electron effects in nanoscale metal-insulator-metal (MIM) structures are investigated using a non-contact X-ray photoelectron spectroscopy based technique using continuous wave X-ray and laser excitations. The effects are observed through shifts of the binding energy of the top metal layer upon excitation with lasers of 445, 532, and 650 nm wavelength. The shifts are polarization dependent for plasmonic MIM grating structures fabricated by electron beam lithography. Wide area plasmonic MIM surfaces fabricated using a lithography free route by the dewetting of evaporated Ag on HfO{sub 2} exhibit polarization independent optical absorption and surface photovoltage. Using a simple model and making several assumptions about the magnitude of the photoemission current, the responsivity and external quantum efficiency of wide area plasmonic MIM surfaces are estimated as 500 nA/W and 11 × 10{sup −6} for 445 nm illumination.

  3. Development of surface plasmon resonance sensor for determining zinc ion using novel active nanolayers as probe.

    Science.gov (United States)

    Fen, Yap Wing; Yunus, W Mahmood Mat; Talib, Zainal Abidin; Yusof, Nor Azah

    2015-01-05

    In this study, novel active nanolayers in combination with surface plasmon resonance (SPR) system for zinc ion (Zn(2+)) detection has been developed. The gold surface used for the SPR system was modified with the novel developed active nanolayers, i.e. chitosan and chitosan-tetrabutyl thiuram disulfide (chitosan-TBTDS). Both chitosan and chitosan-TBTDS active layers were fabricated on the gold surface by spin coating technique. The system was used to monitor SPR signal for Zn(2+) in aqueous media with and without sensitivity enhancement by TBTDS. For both active nanolayers, the shift of resonance angle is directly proportional to the concentration of Zn(2+) in aqueous media. The higher shift of resonance angle was obtained for chitosan-TBTDS active nanolayer due to a specific binding of TBTDS with Zn(2+). The chitosan-TBTDS active nanolayer enhanced the sensitivity of detection down to 0.1 mg/l and also induced a selective detection towards Zn(2+). Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Electronic excited states as a probe of surface adsorbate structure and dynamics in liquid xenon

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, E.S.

    1992-08-01

    A combination of second harmonic generation (SHG) and a simple dipole-dipole interaction model is presented as a new technique for determining adsorbate geometries on surfaces. The polarization dependence of SHG is used to define possible geometries of the adsorbate about the surface normal. Absorption band shifts using geometry constraints imposed by SHG data are derived for a dimer constructed from two arbitrarily placed monomers on the surface using the dipole-dipole interaction potential. These formulae can be used to determine the orientation of the two monomers relative to each other. A simplified version of this formalism is used to interpret absorption band shifts for rhodamine B adsorbed on fused silica. A brief history of the exciton is given with particular detail to Xe. Data are presented for transient absorption at RT in liquid xenon on the picosecond time scale. These are observations of both tunneling through the barrier that separates the free and trapped exciton states and the subsequent trapping of the exciton. In high densities both of these processes are found to occur within 2 to 6 picoseconds in agreement with theories of Kmiecik and Schreiber and of Martin. A threshold density is observed that separates relaxation via single binary collisions and relaxation that proceeds via Martin's resonant energy transfer hopping mechanism.

  5. Electronic excited states as a probe of surface adsorbate structure and dynamics in liquid xenon

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, Eric Scott [Univ. of California, Berkeley, CA (United States)

    1992-08-01

    A combination of second harmonic generation (SHG) and a simple dipole-dipole interaction model is presented as a new technique for determining adsorbate geometries on surfaces. The polarization dependence of SHG is used to define possible geometries of the adsorbate about the surface normal. Absorption band shifts using geometry constraints imposed by SHG data are derived for a dimer constructed from two arbitrarily placed monomers on the surface using the dipole-dipole interaction potential. These formulae can be used to determine the orientation of the two monomers relative to each other. A simplified version of this formalism is used to interpret absorption band shifts for rhodamine B adsorbed on fused silica. A brief history of the exciton is given with particular detail to Xe. Data are presented for transient absorption at RT in liquid xenon on the picosecond time scale. These are observations of both tunneling through the barrier that separates the free and trapped exciton states and the subsequent trapping of the exciton. In high densities both of these processes are found to occur within 2 to 6 picoseconds in agreement with theories of Kmiecik and Schreiber and of Martin. A threshold density is observed that separates relaxation via single binary collisions and relaxation that proceeds via Martin`s resonant energy transfer hopping mechanism.

  6. Inversion of membrane surface charge by trivalent cations probed with a cation-selective channel.

    Science.gov (United States)

    Gurnev, Philip A; Bezrukov, Sergey M

    2012-11-13

    We demonstrate that the cation-selective channel formed by gramicidin A can be used as a reliable sensor for studying the multivalent ion accumulation at the surfaces of charged lipid membranes and the "charge inversion" phenomenon. In asymmetrically charged membranes with the individual leaflets formed from pure negative and positive lipids bathed by 0.1 M CsCl solutions the channel exhibits current rectification, which is comparable to that of a typical n/p semiconductor diode. We show that even at these highly asymmetrical conditions the channel conductance can be satisfactorily described by the electrodiffusion equation in the constant field approximation but, due to predictable limitations, only when the applied voltages do not exceed 50 mV. Analysis of the changes in the voltage-dependent channel conductance upon addition of trivalent cations allows us to gauge their interactions with the membrane surface. The inversion of the sign of the effective surface charge takes place at the concentrations, which correlate with the cation size. Specifically, these concentrations are close to 0.05 mM for lanthanum, 0.25 mM for hexaamminecobalt, and 4 mM for spermidine.

  7. Probing adsorption phenomena on a single crystal Pt-alloy surface under oxygen reduction reaction conditions

    DEFF Research Database (Denmark)

    Bondarenko, Alexander S.; Stephens, Ifan E.L.; Bech, Lone

    2012-01-01

    The adsorption dynamics of *OH and *O species at Pt(111) and Cu/Pt(111) near-surface alloy (NSA) surfaces in oxygen-free and O2-saturated 0.1M HClO4 was investigated. Subsurface Cu modifies the electronic structure at the Pt(111) surface resulting in weaker bonding to adsorbates like *OH, *H or *O....... This provides a basis for the high oxygen reduction activity of the NSA, as predicted by density functional theory calculations. The shift in *OH adsorption of around 0.16V towards more positive potentials can be clearly monitored in absence of O2 and under the oxygen reduction reaction (ORR) conditions...... for the Cu/Pt(111) NSA. In both cases, for Pt(111) and NSA, the *OH(*O) adsorption dynamics is very similar in the absence of oxygen and under ORR conditions. Therefore, theoretical assumptions about the coverage of adsorbates in the absence of oxygen can be reasonably extrapolated to the situation when...

  8. Enhanced Dynamics of Hydrated tRNA on Nanodiamond Surfaces: A Combined Neutron Scattering and MD Simulation Study.

    Science.gov (United States)

    Dhindsa, Gurpreet K; Bhowmik, Debsindhu; Goswami, Monojoy; O'Neill, Hugh; Mamontov, Eugene; Sumpter, Bobby G; Hong, Liang; Ganesh, Panchapakesan; Chu, Xiang-Qiang

    2016-09-14

    Nontoxic, biocompatible nanodiamonds (ND) have recently been implemented in rational, systematic design of optimal therapeutic use in nanomedicines. However, hydrophilicity of the ND surface strongly influences structure and dynamics of biomolecules that restrict in situ applications of ND. Therefore, fundamental understanding of the impact of hydrophilic ND surface on biomolecules at the molecular level is essential. For tRNA, we observe an enhancement of dynamical behavior in the presence of ND contrary to generally observed slow motion at strongly interacting interfaces. We took advantage of neutron scattering experiments and computer simulations to demonstrate this atypical faster dynamics of tRNA on ND surface. The strong attractive interactions between ND, tRNA, and water give rise to unlike dynamical behavior and structural changes of tRNA in front of ND compared to without ND. Our new findings may provide new design principles for safer, improved drug delivery platforms.

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

    Czech Academy of Sciences Publication Activity Database

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

    2013-01-01

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

  10. Quantitative Caffeine Analysis Using a Surface Sampling Probe Electrospray Ionization Tandem Mass Spectrometry System

    Energy Technology Data Exchange (ETDEWEB)

    Ford, Michael J [ORNL; Deibel, Michael A. [Earlham College; Tomkins, Bruce A [ORNL; Van Berkel, Gary J [ORNL

    2005-01-01

    Quantitative determination of caffeine on reversed-phase C8 thin-layer chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The thin-layer chromatography/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment requiring 35 min at a surface scan rate of 44 {mu}m/s. A reversed-phase HPLC/UV caffeine assay was developed in parallel to assess the mass spectrometry method performance. Limits of detection for the HPLC/UV and thin-layer chromatography/electrospray tandem mass spectrometry methods determined from the calibration curve statistics were 0.20 ng injected (0.50 {mu}L) and 1.0 ng spotted on the plate, respectively. Spike recoveries with standards and real samples ranged between 97 and 106% for both methods. The caffeine content of three diet soft drinks (Diet Coke, Diet Cherry Coke, Diet Pepsi) and three diet sport drinks (Diet Turbo Tea, Speed Stack Grape, Speed Stack Fruit Punch) was measured. The HPLC/UV and mass spectrometry determinations were in general agreement, and these values were consistent with the quoted values for two of the three diet colas. In the case of Diet Cherry Coke and the diet sports drinks, the determined caffeine amounts using both methods were consistently higher (by 8% or more) than the literature values.

  11. Reversal of atomic contrast in scanning probe microscopy on (111) metal surfaces

    Czech Academy of Sciences Publication Activity Database

    Ondráček, Martin; González, C.; Jelínek, Pavel

    2012-01-01

    Roč. 24, 08 (2012), 084003/1-084003/7 ISSN 0953-8984 R&D Projects: GA ČR(CZ) GPP204/11/P578; GA ČR GAP204/10/0952; GA ČR GA202/09/0545; GA MŠk(CZ) ME10076 Grant - others:AVČR(CZ) M100100904 Institutional research plan: CEZ:AV0Z10100521 Keywords : atomic force microscopy * metallic surfaces * atomic contrast * scanning tunneling microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.355, year: 2012 http://iopscience.iop.org/0953-8984/24/8/084003

  12. Polarized X-Ray Emission from Magnetized Neutron Stars: Signature of Strong-Field Vacuum Polarization

    Science.gov (United States)

    Lai, Dong; Ho, Wynn C.

    2003-08-01

    In the atmospheric plasma of a strongly magnetized neutron star, vacuum polarization can induce a Mikheyev-Smirnov-Wolfenstein type resonance across which an x-ray photon may (depending on its energy) convert from one mode into the other, with significant changes in opacities and polarizations. We show that this vacuum resonance effect gives rise to a unique energy-dependent polarization signature in the surface emission from neutron stars. The detection of polarized x rays from neutron stars can provide a direct probe of strong-field quantum electrodynamics and constrain the neutron star magnetic field and geometry.

  13. Polarized x-ray emission from magnetized neutron stars: signature of strong-field vacuum polarization.

    Science.gov (United States)

    Lai, Dong; Ho, Wynn C G

    2003-08-15

    In the atmospheric plasma of a strongly magnetized neutron star, vacuum polarization can induce a Mikheyev-Smirnov-Wolfenstein type resonance across which an x-ray photon may (depending on its energy) convert from one mode into the other, with significant changes in opacities and polarizations. We show that this vacuum resonance effect gives rise to a unique energy-dependent polarization signature in the surface emission from neutron stars. The detection of polarized x rays from neutron stars can provide a direct probe of strong-field quantum electrodynamics and constrain the neutron star magnetic field and geometry.

  14. Optical properties of single semiconductor nanowires and nanowire ensembles. Probing surface physics by photoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pfueller, Carsten

    2011-06-27

    This thesis presents a detailed investigation of the optical properties of semiconductor nanowires (NWs) in general and single GaN NWs and GaN NW ensembles in particular by photoluminescence (PL) spectroscopy. NWs are often considered as potential building blocks for future nanometer-scaled devices. This vision is based on several attractive features that are generally ascribed to NWs. For instance, they are expected to grow virtually free of strain and defects even on substrates with a large structural mismatch. In the first part of the thesis, some of these expectations are examined using semiconductor NWs of different materials. On the basis of the temperature-dependent PL of Au- and selfassisted GaAs/(Al,Ga)As core-shell NWs, the influence of foreign catalyst particles on the optical properties of NWs is investigated. For the Au-assisted NWs, we find a thermally activated, nonradiative recombination channel, possibly related to Auatoms incorporated from the catalyst. These results indicate the limited suitability of catalyst-assisted NWs for optoelectronic applications. The effect of the substrate choice is studied by comparing the PL of ZnO NWs grown on Si, Al{sub 2}O{sub 3}, and ZnO substrates. Their virtually identical optical characteristics indicate that the synthesis of NWs may indeed overcome the constraints that limit the heteroepitaxial deposition of thin films. The major part of this thesis discusses the optical properties of GaN NWs grown on Si substrates. The investigation of the PL of single GaN NWs and GaN NW ensembles reveals the significance of their large surface-to-volume ratio. Differences in the recombination behavior of GaNNW ensembles and GaN layers are observed. First, the large surface-to-volume ratio is discussed to be responsible for the different recombination mechanisms apparent in NWs. Second, certain optical features are only found in the PL of GaN NWs, but not in that of GaN layers. An unexpected broadening of the donor

  15. Nuclear reactions of neutron-rich Sn isotopes investigated at relativistic energies at R{sup 3}B

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Fabia; Aumann, Thomas; Horvat, Andrea [TU Darmstadt (Germany); Boretzky, Konstanze [GSI Helmholtzzentrum (Germany); Schrock, Philipp [CNS, University of Tokyo (Japan); Johansen, Jacob [Aarhus University (Denmark); Collaboration: R3B-Collaboration

    2016-07-01

    Nuclei with a large neutron excess are expected to form a neutron-rich surface layer which is often referred to as the neutron skin. The investigation of this phenomenon is of great interest in nuclear-structure physics and offers a possibility to constrain the equation-of-state of neutron-rich matter. Assuming a geometrical description of reaction processes as in the eikonal approximation, nuclear-induced reactions are a good tool to probe the neutron skin. Measured reaction cross sections can be used to constrain the density distributions of protons and neutrons in the nucleus and therefore the neutron-skin thickness. For this purpose, reactions of neutron-rich tin isotopes in the A=124-134 mass range have been measured on a carbon target at the R{sup 3}B-setup at GSI in inverse kinematics in a kinematically complete manner. Preliminary results for the reaction cross sections of {sup 124}Sn are presented.

  16. Characterization of ion-irradiation-induced nanodot structures on InP surfaces by atom probe tomography.

    Science.gov (United States)

    Gnaser, Hubert; Radny, Tobias

    2015-12-01

    Surfaces of InP were bombarded by 1.9 keV Ar(+) ions under normal incidence. The total accumulated ion fluence the samples were exposed to was varied from 1 × 10(17) cm(-2) to 3 × 10(18)cm(-2) and ion flux densities f of (0.4-2) × 10(14) cm(-2) s(-1) were used. Nanodot structures were found to evolve on the surface from these ion irradiations, their dimensions however, depend on the specific bombardment conditions. The resulting surface morphology was examined by atomic force microscopy (AFM). As a function of ion fluence, the mean radius, height, and spacing of the dots can be fitted by power-law dependences. In order to determine possible local compositional changes in these nanostructures induced by ion impact, selected samples were prepared for atom probe tomography (APT). The results indicate that by APT the composition of individual InP nanodots evolving under ion bombardment could be examined with atomic spatial resolution. At the InP surface, the values of the In/P concentration ratio are distinctly higher over a distance of ~1 nm and amount to 1.3-1.8. However, several aspects critical for the analyses were identified: (i) because of the small dimensions of these nanostructures a successful tip preparation proved very challenging. (ii) The elemental compositions obtained from APT were found to be influenced pronouncedly by the laser pulse energy; typically, low energies result in the correct stoichiometry whereas high ones lead to an inhomogeneous evaporation from the tips and deviations from the nominal composition. (iii) Depending again on the laser energy, a prolific emission of Pn cluster ions was observed, with n ≤ 11. Copyright © 2015. Published by Elsevier B.V.

  17. Immobilization of oligonucleotide probes on silicon surfaces using biotin–streptavidin system examined with microscopic and spectroscopic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Awsiuk, K., E-mail: kamil.awsiuk@uj.edu.pl [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, Kraków 30-059 (Poland); Rysz, J. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, Kraków 30-059 (Poland); Petrou, P. [Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety, NCSR “Demokritos”, End Patriarchou Gregoriou Str., Aghia Paraskevi 15310 (Greece); Budkowski, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, Kraków 30-059 (Poland); Bernasik, A. [Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, Kraków 30-059 (Poland); Kakabakos, S. [Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety, NCSR “Demokritos”, End Patriarchou Gregoriou Str., Aghia Paraskevi 15310 (Greece); Marzec, M.M. [Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, Kraków 30-059 (Poland); Raptis, I. [Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, NCSR “Demokritos”, End Patriarchou Gregoriou Str., Aghia Paraskevi 15310 (Greece)

    2014-01-30

    To immobilize effectively oligonucleotide probes on SiO{sub 2} modified with (3-aminopropyl)triethoxysilane, four procedures based on streptavidin–biotin system are compared with Atomic Force Microscopy, Angle-Resolved X-ray Photoelectron Spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry. The first approach involves: adsorption of biotinylated Bovine Serum Albumin, blocking free surface sites with BSA, binding of streptavidin and biotinylated oligonucleotide (b-oligo). Final steps are exchanged in the second procedure with immobilization of preformed streptavidin–b-oligo conjugate. The third approach consists of streptavidin adsorption, blocking with BSA and b-oligo binding. Finally, streptavidin–b-oligo conjugate is immobilized directly within the fourth method. Surface coverage with biomolecules, determined from ARXPS, accords with average AFM height, and is anti-correlated with the intensity of Si+ ions. Higher biomolecular coverage was achieved during the last steps of the first (2.45(±0.38) mg/m{sup 2}) and second (1.31(±0.22) mg/m{sup 2}) approach, as compared to lower surface density resulting from the third (0.58(±0.20) mg/m{sup 2}) and fourth (0.41(±0.11) mg/m{sup 2}) method. Phosphorus atomic concentration indicates effectiveness of oligonucleotide immobilization. Secondary ions intensities, characteristic for oligonucleotides, streptavidin, BSA, and proteins, allow additional insight into overlayer composition. These measurements verify the ARXPS results and show the superiority of the first two immobilization approaches in terms of streptavidin and oligonucleotide density achieved onto the surface.

  18. Immobilization of oligonucleotide probes on silicon surfaces using biotin–streptavidin system examined with microscopic and spectroscopic techniques

    International Nuclear Information System (INIS)

    Awsiuk, K.; Rysz, J.; Petrou, P.; Budkowski, A.; Bernasik, A.; Kakabakos, S.; Marzec, M.M.; Raptis, I.

    2014-01-01

    To immobilize effectively oligonucleotide probes on SiO 2 modified with (3-aminopropyl)triethoxysilane, four procedures based on streptavidin–biotin system are compared with Atomic Force Microscopy, Angle-Resolved X-ray Photoelectron Spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry. The first approach involves: adsorption of biotinylated Bovine Serum Albumin, blocking free surface sites with BSA, binding of streptavidin and biotinylated oligonucleotide (b-oligo). Final steps are exchanged in the second procedure with immobilization of preformed streptavidin–b-oligo conjugate. The third approach consists of streptavidin adsorption, blocking with BSA and b-oligo binding. Finally, streptavidin–b-oligo conjugate is immobilized directly within the fourth method. Surface coverage with biomolecules, determined from ARXPS, accords with average AFM height, and is anti-correlated with the intensity of Si+ ions. Higher biomolecular coverage was achieved during the last steps of the first (2.45(±0.38) mg/m 2 ) and second (1.31(±0.22) mg/m 2 ) approach, as compared to lower surface density resulting from the third (0.58(±0.20) mg/m 2 ) and fourth (0.41(±0.11) mg/m 2 ) method. Phosphorus atomic concentration indicates effectiveness of oligonucleotide immobilization. Secondary ions intensities, characteristic for oligonucleotides, streptavidin, BSA, and proteins, allow additional insight into overlayer composition. These measurements verify the ARXPS results and show the superiority of the first two immobilization approaches in terms of streptavidin and oligonucleotide density achieved onto the surface.

  19. Single- and multi-frequency detection of surface displacements via scanning probe microscopy.

    Science.gov (United States)

    Romanyuk, Konstantin; Luchkin, Sergey Yu; Ivanov, Maxim; Kalinin, Arseny; Kholkin, Andrei L

    2015-02-01

    Piezoresponse force microscopy (PFM) provides a novel opportunity to detect picometer-level displacements induced by an electric field applied through a conducting tip of an atomic force microscope (AFM). Recently, it was discovered that superb vertical sensitivity provided by PFM is high enough to monitor electric-field-induced ionic displacements in solids, the technique being referred to as electrochemical strain microscopy (ESM). ESM has been implemented only in multi-frequency detection modes such as dual AC resonance tracking (DART) and band excitation, where the response is recorded within a finite frequency range, typically around the first contact resonance. In this paper, we analyze and compare signal-to-noise ratios of the conventional single-frequency method with multi-frequency regimes of measuring surface displacements. Single-frequency detection ESM is demonstrated using a commercial AFM.

  20. Measurement of molecular length of self-assembled monolayer probed by localized surface plasmon resonance

    Science.gov (United States)

    Ito, Juri; Kajikawa, Kotaro

    2016-02-01

    We propose a method to measure the variation of the molecular length of self-assembled monolayers (SAMs) when it is exposed to solutions at different pH conditions. The surface immobilized gold nanospheres (SIGNs) shows strong absorption peak at the wavelengths of 600-800 nm when p-polarized light is illuminated. The peak wavelength depends on the length of the gap distance between the SIGNs and the substrate. The gap is supported by the SAM molecules. According to the analytical calculation based on multiple expansion, the relation between the peak wavelength of the SIGN structures and the gap distance is calculated, to evaluate the molecular length of the SAM through the optical absorption spectroscopy for the SIGN structures. The molecular length of the SIGN structure was measured in air, water, acidic, and basic solutions. It was found that the molecular lengths are longer in acidic solutions.

  1. Hollow-Core Photonic Crystal Fibers for Surface-Enhanced Raman Scattering Probes

    Directory of Open Access Journals (Sweden)

    Xuan Yang

    2011-01-01

    Full Text Available Photonic crystal fiber (PCF sensors based on surface-enhanced Raman scattering (SERS have become increasingly attractive in chemical and biological detections due to the molecular specificity, high sensitivity, and flexibility. In this paper, we review the development of PCF SERS sensors with emphasis on our recent work on SERS sensors utilizing hollow-core photonic crystal fibers (HCPCFs. Specifically, we discuss and compare various HCPCF SERS sensors, including the liquid-filled HCPCF and liquid-core photonic crystal fibers (LCPCFs. We experimentally demonstrate and theoretically analyze the high sensitivity of the HCPCF SERS sensors. Various molecules including Rhodamine B, Rhodamine 6G, human insulin, and tryptophan have been tested to show the excellent performance of these fiber sensors.

  2. Probing cytochrome c in living mitochondria with surface-enhanced Raman spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda A.; Evlyukhin, Andrey B.; Goodilin, Eugene A.

    2015-01-01

    Selective study of the electron transport chain components in living mitochondria is essential for fundamental biophysical research and for the development of new medical diagnostic methods. However, many important details of inter- and intramembrane mitochondrial processes have remained in shadow...... due to the lack of non-invasive techniques. Here we suggest a novel label-free approach based on the surface-enhanced Raman spectroscopy (SERS) to monitor the redox state and conformation of cytochrome c in the electron transport chain in living mitochondria. We demonstrate that SERS spectra of living...... mitochondria placed on hierarchically structured silver-ring substrates provide exclusive information about cytochrome c behavior under modulation of inner mitochondrial membrane potential, proton gradient and the activity of ATP-synthetase. Mathematical simulation explains the observed enhancement of Raman...

  3. Surface-modified CdS nanoparticles as a fluorescent probe for the selective detection of cysteine

    International Nuclear Information System (INIS)

    Negi, Devendra P S; Chanu, T Inakhunbi

    2008-01-01

    We present a novel method for the selective detection of cysteine, a sulfur-containing amino acid, which plays a crucial role in many important biological functions such as protein folding. Surface-modified colloidal CdS nanoparticles have been used as a fluorescent probe to selectively detect cysteine in the presence of other amino acids in the micromolar concentration range. Cysteine quenches the emission of CdS in the 0.5-10 μM concentration range, whereas the other amino acids do not affect its emission. Among the other amino acids, histidine is most efficient in quenching the emission of the CdS nanoparticles. The sulfur atom of cysteine plays a crucial role in the quenching process in the 0.5-10 μM concentration range. Cysteine is believed to quench the emission of the CdS nanoparticles by binding to their surface via its negatively charged sulfur atom. This method can potentially be applied for its detection in biological samples.

  4. PREFACE: Fundamental Neutron Physics: Introduction and Overview Fundamental Neutron Physics: Introduction and Overview

    Science.gov (United States)

    Holstein, Barry R.

    2009-10-01

    fundamental nature, the structure of the neutron itself can be used to probe hadronic structure, via measurement of its electromagnetic form factors and/or polarizabilities. This aspect of neutron physics is discussed in the article by Daniel Phillips. In a set of measurements at Grenoble, the neutron has been used to study its quantum mechanical gravitational bound state in the vicinity of the Earth's surface. This work is described in the article by Stefan Baessler. Finally, possible beyond standard model physics is probed by experimental searches for neutron-antineutron oscillations, as discussed in the article by Rabi Mohaptatra. There exist many other areas wherein the neutron has been used as a probe of fundamental pieces of contemporary physics. Examples include the use of neutron interferometry to measure the Earth's rotation and gravitational field and the recent use of light cone methods to study the transverse charge distribution of the neutron. Indeed, a full report on all such aspects could fill an entire volume of Journal of Physics G: Nuclear and Particle Physics. The six articles which appear here in this focus section are presented rather as a brief overview, to possibly whet the appetite of the reader for such work. Hungrier readers can fill their plate with additional and more detailed information available in the many references cited by the focus articles or in more extensive discussions available elsewhere. An example is the article on experiments in fundamental neutron physics by Jeff Nico and Mike Snow published in Annual Reviews of Nuclear and Particle Science 2005 55 27-69, but there are many others.

  5. Chemically stable Au nanorods as probes for sensitive surface enhanced scattering (SERS) analysis of blue BIC ballpoint pens

    Science.gov (United States)

    Alyami, Abeer; Saviello, Daniela; McAuliffe, Micheal A. P.; Cucciniello, Raffaele; Mirabile, Antonio; Proto, Antonio; Lewis, Liam; Iacopino, Daniela

    2017-08-01

    Au nanorods were used as an alternative to commonly used Ag nanoparticles as Surface Enhanced Raman Scattering (SERS) probes for identification of dye composition of blue BIC ballpoint pens. When used in combination with Thin Layer Chromatography (TLC), Au nanorod colloids allowed identification of the major dye components of the BIC pen ink, otherwise not identifiable by normal Raman spectroscopy. Thanks to their enhanced chemical stability compared to Ag colloids, Au nanorods provided stable and reproducible SERS signals and allowed easy identification of phthalocyanine and triarylene dyes in the pen ink mixture. These findings were supported by FTIR and MALDI analyses, also performed on the pen ink. Furthermore, the self-assembly of Au nanorods into large area ordered superstructures allowed identification of BIC pen traces. SERS spectra of good intensity and high reproducibility were obtained using Au nanorod vertical arrays, due to the high density of hot spots and morphological reproducibility of these superstructures. These results open the way to the employment of SERS for fast screening analysis and for quantitative analysis of pens and faded pens which are relevant for the fields of forensic and art conservation sciences.

  6. A Surface Plasmon Resonance-Based Optical Fiber Probe Fabricated with Electropolymerized Molecular Imprinting Film for Melamine Detection

    Directory of Open Access Journals (Sweden)

    Wei Li

    2018-03-01

    Full Text Available Molecularly imprinted polymer (MIP films prepared by bulk polymerization suffer from numerous deficiencies, including poor mass transfer ability and difficulty in controlling reaction rate and film thickness, which usually result in poor repeatability. However, polymer film synthesized by electropolymerization methods benefit from high reproducibility, simplicity and rapidity of preparation. In the present study, an Au film served as the refractive index-sensitive metal film to couple with the light leaked out from optical fiber core and the electrode for electropolymerizing MIP film simultaneously. The manufactured probe exhibited satisfactory sensitivity and specificity. Furthermore, the surface morphology and functional groups of the synthesized MIP film were characterized by Atomic Force Microscopy (AFM and Fourier transform infrared microspectroscopy (FTIR for further insights into the adsorption and desorption processes. Given the low cost, label-free test, simple preparation process and fast response, this method has a potential application to monitor substances in complicated real samples for out-of-lab test in the future.

  7. Measuring the Thermal Conductivity of Sediments for the Estimation of Groundwater Discharge to Surface Waters with Temperature Probes

    Science.gov (United States)

    Duque, C.; Müller, S.; Sebok, E.; Engesgaard, P. K.

    2015-12-01

    Using temperature probes is a common exploratory method for studying groundwater-surface water interaction due to the ease for collecting measurements and the simplicity of the different analytical solutions. This approach requires to define the surface water temperature, the groundwater temperature and a set of parameters (density and specific capacity of water, and thermal conductivity of sediments) that can be easily extracted from tabulated values under the assumption that they are homogeneous in the study area. In the case of the thermal conductivity, it is common to apply a standard value of 1.84 Wm-1 C-1 corresponding to sand. Nevertheless the environments where this method is applied, like streambeds or lake/lagoons shores, are sedimentary depositional systems with high energy and biological activity that often lead to sediments dominated by organic matter or sharp changes in grain size modifying greatly the thermal conductivity values. In this study, the thermal conductivity was measured in situ along transects where vertical temperature profiles were collected in a coastal lagoon bed receiving groundwater discharge (Ringkøbing Fjord, Denmark). A set of 4 transects with 10-20 temperature profiles during 3 different seasons was analyzed together with more than 150 thermal conductivity measurements along the working transects and in experimental parcels of 1 m2 where the cm scale spatial variability of the thermal conductivity was assessed. The application of a literature-based bulk thermal conductivity of 1.84 Wm-1 C-1 instead of field data that ranged from 0.62 to 2.19 Wm-1 C-1, produced a mean flux overestimation of 2.33 cm d-1 that, considering the low fluxes of the study area, represents an increase of 89 % and up to a factor of 3 in the most extreme cases. The changes in thermal conductivity can alter the estimated fluxes hindering the detection of patterns in groundwater discharge and modifying the interpretation of the results.

  8. Experimental study of angular neutron flux spectra on a slab surface to assess nuclear data and calculational methods for a fusion reactor design

    International Nuclear Information System (INIS)

    Oyama, Yukio

    1988-06-01

    This paper presents an experimental approach to interpret the results of integral experiments for fusion neutronics research. The measurement is described of the angular neutron flux on a restricted area of slab assemblies with D-T neutron bombardment by using the time-of-flight (TOF) method with an NE213 neutron detector over an energy range from 0.05 to 15 MeV. A two bias scheme was developed to obtain an accurate detection efficiency over a wide energy range. The detector-collimator response function was introduced to define the restricted surface area and to determine the effective measured area. A series of measurements of the angular neutron flux on slabs of fusion blanket materials, i.e., Be, C, and Li 2 O, as functions of neutron leaking angle and slab thickness have been performed to examine neutron transport characteristics in bulk materials. The calculational analyses of the experimental results have been also carried out by using Monte Carlo neutron transport codes, i.e., MORSE-DD and MCNP. The existing nuclear data files, i.e., JENDL-3PR1, -3PR2, ENDF/B-IV and -V were tested by comparing with the experimental results. From the comparisons, the data on C and 7 Li in the present files are fairly sufficient. Those on beryllium, however, is insufficient for the estimation of high threshold reactions such as tritium production in a fusion reactor blanket design. It is also found that the total and elastic cross sections are more important for accurate predictions of neutronic parameters at deep position. The comparisons between the measured and calculated results provide information to understand the results of the previous integral experiments for confirmation of accuracy of fusion reactor designs. (author)

  9. Anisotropic excitation of surface plasmon polaritons on a metal film by a scattering-type scanning near-field microscope with a non-rotationally-symmetric probe tip

    Directory of Open Access Journals (Sweden)

    Walla Frederik

    2018-01-01

    Full Text Available We investigated the excitation of surface plasmon polaritons on gold films with the metallized probe tip of a scattering-type scanning near-field optical microscope (s-SNOM. The emission of the polaritons from the tip, illuminated by near-infrared laser radiation, was found to be anisotropic and not circularly symmetric as expected on the basis of literature data. We furthermore identified an additional excitation channel via light that was reflected off the tip and excited the plasmon polaritons at the edge of the metal film. Our results, while obtained for a non-rotationally-symmetric type of probe tip and thus specific for this situation, indicate that when an s-SNOM is employed for the investigation of plasmonic structures, the unintentional excitation of surface waves and anisotropic surface wave propagation must be considered in order to correctly interpret the signatures of plasmon polariton generation and propagation.

  10. Neutron reflectometry

    DEFF Research Database (Denmark)

    Klösgen-Buchkremer, Beate Maria

    2014-01-01

    of desired information. In the course, an introduction into the method and an overview on selected instruments at large scale facilities will be presented. Examples will be given that illustrate the potential of the method, mostly based on organic films. Results from the investigation of layered films......Neutron (and X-ray) reflectometry constitute complementary interfacially sensitive techniques that open access to studying the structure within thin films of both soft and hard condensed matter. Film thickness starts oxide surfaces on bulk substrates, proceeding to (pauci-)molecular layers and up...... films or films with magnetic properties. The reason is the peculiar property of neutron light since the mass of a neutron is close to the one of a proton, and since it bears a magnetic moment. The optical properties of matter, when interacting with neutrons, are described by a refractive index...

  11. Mitigation technologies for damage induced by pressure waves in high-power mercury spallation neutron sources (1). Material surface improvement

    International Nuclear Information System (INIS)

    Naoe, Takashi; Futakawa, Masatoshi; Wakui, Takashi; Kogawa, Hiroyuki; Shoubu, Takahisa; Takeuchi, Hirotsugu; Kawai, Masayoshi

    2008-01-01

    Liquid-mercury target systems for MW-class spallation neutron sources are being developed in the world. Proton beams will be used to induce the spallation reaction. At the moment the proton beam hits the target, pressure waves are generated in the mercury because of the abrupt heat deposition. The pressure waves interact with the target vessel leading to negative pressure that may cause cavitation along the vessel wall. Localized impacts by microjets and/or shock waves that are caused by cavitation bubble collapse impose pitting damage on the vessel wall. Bubble collapse behavior was observed by using a high-speed video camera, as well as simulated numerically. Localized impact due to cavitation bubble collapse was quantitatively estimated through comparison between numerical simulation and experiment. A novel surface treatment technique that consists of carburizing and nitriding processes was developed and the treatment condition was optimized to mitigate the pitting damage due to localized impacts. (author)

  12. Neutron stars

    International Nuclear Information System (INIS)

    Irvine, J.M.

    1978-01-01

    The subject is covered in chapters entitled: introduction (resume of stellar evolution, gross characteristics of neutron stars); pulsars (pulsar characteristics, pulsars as neutron stars); neutron star temperatures (neutron star cooling, superfluidity and superconductivity in neutron stars); the exterior of neutron stars (the magnetosphere, the neutron star 'atmosphere', pulses); neutron star structure; neutron star equations of state. (U.K.)

  13. Direct observation of the near-surface layer in Pb(Mg1/3Nb2/3)O3 using neutron diffraction

    International Nuclear Information System (INIS)

    Conlon, K.H.; Whan, T.; Fox, J.H.; Luo, H.; Viehland, D.; Li, J.F.; Stock, C.; Shirane, G.

    2004-01-01

    Spatially resolved neutron diffraction as a function of crystal depth in Pb(Mg 1/3 Nb 2/3 )O 3 reveals the presence of a distinct near-surface region where a strong distortion in the lattice exists. A dramatic change in both the lattice constant and the Bragg peak intensity as a function of crystal depth is observed to occur in this region over a length scale ∼100 μm. This confirms a previous assertion, based on a comparison between high-energy x rays and neutrons, that such a near surface region exists in the relaxors. Consequences to both single crystal and powder diffraction measurements and previous bulk neutron diffraction measurements on large single crystals are discussed

  14. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    Duvaa, Uffe; Ørngreen, Rikke; Weinkouff Mathiasen, Anne-Gitte

    2013-01-01

    Mobile probing is a method, developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time and space......). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings point...... to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...

  15. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    Duvaa, Uffe; Ørngreen, Rikke; Weinkouff, Anne-Gitte

    2012-01-01

    Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...

  16. Probing Interaction Between Platinum Group Metal (PGM) and Non-PGM Support Through Surface Characterization and Device Performance

    Science.gov (United States)

    Saha, Shibely

    High cost and limited abundance of Platinum (Pt) have hindered effective commercialization of Proton Exchange Membrane Fuel Cell and Electrolyzer. Efforts have been undertaken to reduce precious group metal (PGM) requirement for these devices without compromising the activity of the catalyst by using transition metal carbides (TMC) as non-PGM support thanks to their similar electronic and geometric structures as Pt. In this work Mo2C was selected as non-PGM support and Pt was used as the PGM of interest. We hypothesize that the hollow nanotube morphology of Mo2C support combined with Pt nano particles deposited on it via atomic layer deposition (ALD) technique would allow increased interaction between them which may increase the activity of Pt and Mo2C as well as maximize the Pt active surface area. Specifically, a rotary ALD equipment was used to grow Pt particles from atomic level to 2--3 nanometers by simply adjusting number of ALD cycles in order to probe the interaction between the deposited Pt nanoparticles and Mo2C nanotube support. Interaction between the Pt and Mo2 C was analyzed via surface characterization and electrochemical characterization. Interaction between Pt and Mo2C arises due to the lattice mismatch between Pt and Mo2C as well as electron migration between them. Lattice spacing analysis using high resolution transmission electron microscopy (HRTEM) images, combined with Pt binding energy shift in XPS results, clearly showed strong bonding between Pt nanoparticles and the Mo2C nanotube support in all the resultant Pt/Mo2C samples. We postulate that this strong interaction is responsible for the significantly enhanced durability observed in our constant potential electrolysis (CPE) and accelerated degradation testing (ADT). Of the three samples from different ALD cycles (15, 50 and 100), Mo2C nanotubes modified by 50 (1.07 wt% Pt loading) and 100 cycles (4.4 wt% Pt) of Pt deposition, showed higher HER and HOR activity per Pt mass than commercial

  17. Cooling of Accretion-Heated Neutron Stars

    Science.gov (United States)

    Wijnands, Rudy; Degenaar, Nathalie; Page, Dany

    2017-09-01

    We present a brief, observational review about the study of the cooling behaviour of accretion-heated neutron stars and the inferences about the neutron-star crust and core that have been obtained from these studies. Accretion of matter during outbursts can heat the crust out of thermal equilibrium with the core and after the accretion episodes are over, the crust will cool down until crust-core equilibrium is restored. We discuss the observed properties of the crust cooling sources and what has been learned about the physics of neutron-star crusts. We also briefly discuss those systems that have been observed long after their outbursts were over, i.e, during times when the crust and core are expected to be in thermal equilibrium. The surface temperature is then a direct probe for the core temperature. By comparing the expected temperatures based on estimates of the accretion history of the targets with the observed ones, the physics of neutron-star cores can be investigated. Finally, we discuss similar studies performed for strongly magnetized neutron stars in which the magnetic field might play an important role in the heating and cooling of the neutron stars.

  18. Small-Angle Neutron Scattering Investigation of Growth Modifiers on Hydrate Crystal Surfaces

    Science.gov (United States)

    Sun, Thomas; Hutter, Jeffrey L.; Lin, M.; King, H. E., Jr.

    1998-03-01

    Hydrates are crystals consisting of small molecules enclathrated within an ice-like water cage. Suppression of their growth is important in the oil industry. The presence of small quantities of specific polymers during hydrate crystallization can induce a transition from an octahedral to planar growth habit. This symmetry breaking is surprising because of the suppression of two 111 planes relative to the other six crystallographically equivalent faces. To better understand the surface effects leading to this behavior, we have studied the surface adsorption of these growth-modifing polymers onto the hydrate crytals using SANS. The total hydrate surface area, as measured by Porod scattering, increases in the presence of the growth modifier, but, no significant increase in polymer concentration on the crystal surfaces is found. Implications for possible growth mechanisms will be discussed.

  19. Stress distribution in mechanically surface treated Ti-2.5Cu determined by combining energy-dispersive synchrotron and neutron diffraction

    International Nuclear Information System (INIS)

    Maawad, E.; Brokmeier, H.-G.; Hofmann, M.; Genzel, Ch.; Wagner, L.

    2010-01-01

    Mechanical surface treatments such as shot peening (SP) or ball-burnishing (BB) induce plastic deformation close to the surface resulting in work-hardening and compressive residual stresses. It enhances the fatigue performance by retarding or even suppressing micro-crack growth from the surface into the interior. SP and BB were carried out on a solution heat treated (SHT) Ti-2.5Cu. The investigations of compressive and balancing tensile residual stresses need a combination of energy-dispersive synchrotron (ED) and neutron diffraction. Essential for the stress distribution is the stress state before surface treatments which was determined by neutron diffraction. Results show that the maximum compressive stress and its depth play an important role to improve the fatigue performance.

  20. Probing surface sites of TiO2: reactions with [HRe(CO)5] and [CH3Re(CO)5].

    Science.gov (United States)

    Lobo-Lapidus, Rodrigo J; Gates, Bruce C

    2010-10-04

    Two carbonyl complexes of rhenium, [HRe(CO)(5)] and [CH(3)Re(CO)(5)], were used to probe surface sites of TiO(2) (anatase). These complexes were adsorbed from the gas phase onto anatase powder that had been treated in flowing O(2) or under vacuum to vary the density of surface OH sites. Infrared (IR) spectra demonstrate the variation in the number of sites, including Ti(+3)-OH and Ti(+4)-OH. IR and extended X-ray absorption fine structure (EXAFS) spectra show that chemisorption of the rhenium complexes led to their decarbonylation, with formation of surface-bound rhenium tricarbonyls, when [HRe(CO)(5)] was adsorbed, or rhenium tetracarbonyls, when [CH(3)Re(CO)(5)] was adsorbed. These reactions were accompanied by the formation of water and surface carbonates and removal of terminal hydroxyl groups associated with Ti(+3) and Ti(+4) ions on the anatase. Data characterizing the samples after adsorption of [HRe(CO)(5)] or [CH(3)Re(CO)(5)] determined a ranking of the reactivity of the surface OH sites, with the Ti(+3)-OH groups being the more reactive towards the rhenium complexes but the less likely to be dehydroxylated. The two rhenium pentacarbonyl probes provided complementary information, suggesting that the carbonate species originate from carbonyl ligands initially bonded to the rhenium and from hydroxyl groups of the titania surface, with the reaction leading to the formation of water and bridging hydroxyl groups on the titania. The results illustrate the value of using a family of organometallic complexes as probes of oxide surface sites.

  1. Magnetic nanostructures: radioactive probes and recent developments

    International Nuclear Information System (INIS)

    Prandolini, M J

    2006-01-01

    The miniaturization of magnetic sensors and storage devices down to the nano-scale leads to drastic changes in magnetic phenomena compared with the same devices with a larger size. Excited-nuclear-probe (radioactive probe) techniques are ideal for investigating these new magnetic nanostructures. By observing the magnetic hyperfine fields (and in some cases the electric-field-gradients (EFGs)) at the nuclei of radioactive probes, microscopic information about the magnetic environment of the probes is acquired. The magnetic hyperfine field is particularly sensitive to the s-spin polarization of the conduction electrons and to the orbital magnetic moment of the probe atom. Three methods of inserting radioactive probes into magnetic nanostructures are presented; neutron activation, recoil implantation and 'soft-landing', followed by descriptions of their application to selected examples. In some cases, these methods offer the simultaneous creation and observation of new magnetic materials at the atomic scale. This review focuses firstly on the induced magnetism in noble-metal spacer layers between either ferromagnetic (FM) or FM/antiferromagnetic (AFM) layers in a trilayer structure. Using the method of low-temperature nuclear orientation, the s-spin polarization of noble-metal probes was measured and was found to be very sensitive to the magnetic properties at both the FM and AFM interfaces. Secondly, the recoil implantation of radioactive Fe probes into rare-earth hosts and d-band alloys and subsequent measurement using time-differential perturbed angular distribution offer the possibility of controlling the chemical composition and number of nearest-neighbours. This method was used to prepare local 3d-magnetic clusters in a non-magnetic matrix and to observe their magnetic behaviour. Finally, non-magnetic radioactive probes were 'soft-landed' onto Ni surfaces and extremely lattice-expanded ultrathin Ni films. By measuring the magnetic hyperfine fields and EFGs at

  2. Measurement of planetary surface composition by gamma-ray and neutron spectrometry - Preparatory studies for Mars and for the Moon by numerical simulations

    International Nuclear Information System (INIS)

    Gasnault, O.

    1999-01-01

    Gamma-ray and neutron spectrometry sets up a powerful tool of geological and geochemical characterization of planetary surfaces. This method allows to tackle some critical planet science questions: crustal and mantle compositions; ices; volcanism; alteration processes... Most of the neutrons and gamma photons result from the interactions of galactic cosmic rays with matter. The first chapter introduces the physics of these nuclear interactions in planetary soils and in detectors. Our work aims at optimizing the observations by specifying instrumental performances, and by highlighting relations between soil composition and neutron fluxes. Numerical simulations using the GEANT code from CERN support our analysis. The second chapter estimates the performances of the Germanium gamma-ray spectrometer for MARS SURVEYOR 2001. The result of simulations is compared to calibration measurements; then performances are calculated in flight configuration. The background at Mars is estimated to about 160 c/s. The instrument offers a fine sensitivity to: Fe, Mg, K, Si, Th, Cl and O. It will also be possible to measure U, Ti, H, C, S, Ca and Al. The emission lobes at the surface are calculated too. These measurements shall permit a better understanding of the Martian surface. The last chapter deals with fast neutrons [500 keV; 10 MeV] emitted by the Moon. The strong influence of oxygen is underlined. As observed by LUNAR PROSPECTOR, the integrated flux shows a pronounced dependence with regolith content in iron and titanium, allowing the mapping. The influence of the other chemical elements is quantified. A simple mathematical formula is suggested to estimate the integrated neutron flux according to soil composition. At last, a study of hydrogen effects on fast neutron flux is carried out; we examine the possibilities to quantify its abundance in the soil by this method. (author)

  3. Probing the semi-magicity of $^{68}$Ni via the $^{3}$H($^{66}$Ni,$^{68}$Ni)p two-neutron transfer reaction in inverse kinematics

    CERN Multimedia

    Reiter, P; Blazhev, A A; Kruecken, R; Franchoo, S; Mertzimekis, T; Darby, I G; Van de walle, J; Raabe, R; Elseviers, J; Gernhaeuser, R A; Sorlin, O H; Georgiev, G P; Bree, N C F; Habs, D; Chapman, R; Gaudefroy, L; Diriken, J V J; Jenkins, D G; Kroell, T; Axiotis, M; Huyse, M L; Patronis, N

    We propose to perform the two-neutron transfer reaction $^{3}$H($^{66}$Ni, $^{68}$Ni)$p$ using the ISOLDE radioactive ion beam at 2.7 $A$ MeV and the MINIBALL + T-REX setup to characterize the 0$^{+}$ and 2$^{+}$ states in $^{68}$Ni.

  4. Magnetic properties of LaCo.sub.12./sub. B.sub.6./sub. compound as probed by neutron diffraction and by magnetization study under high pressures

    Czech Academy of Sciences Publication Activity Database

    Diop, L.V.B.; Arnold, Zdeněk; Isnard, O.; Kamarád, Jiří

    2014-01-01

    Roč. 593, APR (2014), s. 163-168 ISSN 0925-8388 R&D Projects: GA ČR GA202/09/1027 Institutional support: RVO:68378271 Keywords : pressure effect * borides * magnetic properties * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.999, year: 2014

  5. High frequency time modulation of neutrons by LiNbO3 crystals with surface acoustic waves excited under the diffraction condition

    International Nuclear Information System (INIS)

    Takahashi, Toshio; Granzer, E.; Kikuta, Seishi; Tomimitsu, Hiroshi; Doi, Kenji.

    1985-01-01

    High frequency time modulation of neutrons was investigated by using Y-cut LiNbO 3 crystals with surface acoustic waves excited. A double crystal arrangement of (+, -) parallel setting was used for 030 symmetric Bragg-case reflections. Synchronized standing waves with a resonance frequency of 14.26 MHz were excited on the both crystals. Variation of the diffracted intensity with phase difference between two standing waves was studied. The result showed an intensity change of diffracted neutrons with twice the resonance frequency. (author)

  6. Adsorption of a cationic dye molecule on polystyrene microspheres in colloids: effect of surface charge and composition probed by second harmonic generation.

    Science.gov (United States)

    Eckenrode, Heather M; Jen, Shih-Hui; Han, Jun; Yeh, An-Gong; Dai, Hai-Lung

    2005-03-17

    Nonlinear optical probe, second harmonic generation (SHG), of the adsorption of the dye molecule malachite green (MG), in cationic form at pH polystyrene microspheres in aqueous solution is used to study the effect of surface charge and composition on molecular adsorption. Three types of polystyrene microspheres with different surface composition are investigated: (1) a sulfate terminated, anionic surface, (2) a neutral surface without any functional group termination, and (3) an amine terminated, cationic surface. The cationic dye was found to adsorb at all three surfaces, regardless of surface charge. The adsorption free energies, DeltaG's, measured for the three surfaces are -12.67, -12.39, and -10.46 kcal/mol, respectively, with the trend as expected from the charge interactions. The adsorption density on the anionic surface, where attractive charge-charge interaction dominates, is determined by the surface negative charge density. The adsorption densities on the neutral and cationic surfaces are on the other hand higher, perhaps as a result of a balance between minimizing repulsive charge interaction and maximizing attractive molecule-substrate and intermolecular interactions. The relative strength of the SH intensity per molecule, in combination of a model calculation, reveals that the C(2) axis of the MG molecule is nearly perpendicular to the surface on the anionic surface and tilts away from the surface norm when the surface is neutral and further away when cationic. Changing the pH of the solution may alter the surface charge and subsequently affect the adsorption configuration and SH intensity.

  7. THE IMPACT OF SURFACE TEMPERATURE INHOMOGENEITIES ON QUIESCENT NEUTRON STAR RADIUS MEASUREMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Elshamouty, K. G.; Heinke, C. O.; Morsink, S. M.; Stevens, A. L. [Department of Physics, University of Alberta, CCIS 4-181, Edmonton, AB T6G 2E1 (Canada); Bogdanov, S., E-mail: alshamou@ualberta.ca [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, NY 10027 (United States)

    2016-08-01

    Fitting the thermal X-ray spectra of neutron stars (NSs) in quiescent X-ray binaries can constrain the masses and radii of NSs. The effect of undetected hot spots on the spectrum, and thus on the inferred NS mass and radius, has not yet been explored for appropriate atmospheres and spectra. A hot spot would harden the observed spectrum, so that spectral modeling tends to infer radii that are too small. However, a hot spot may also produce detectable pulsations. We simulated the effects of a hot spot on the pulsed fraction and spectrum of the quiescent NSs X5 and X7 in the globular cluster 47 Tucanae, using appropriate spectra and beaming for hydrogen atmosphere models, incorporating special and general relativistic effects, and sampling a range of system angles. We searched for pulsations in archival Chandra HRC-S observations of X5 and X7, placing 90% confidence upper limits on their pulsed fractions below 16%. We use these pulsation limits to constrain the temperature differential of any hot spots, and to then constrain the effects of possible hot spots on the X-ray spectrum and the inferred radius from spectral fitting. We find that hot spots below our pulsation limit could bias the spectroscopically inferred radius downward by up to 28%. For Cen X-4 (which has deeper published pulsation searches), an undetected hot spot could bias its inferred radius downward by up to 10%. Improving constraints on pulsations from quiescent LMXBs may be essential for progress in constraining their radii.

  8. THE IMPACT OF SURFACE TEMPERATURE INHOMOGENEITIES ON QUIESCENT NEUTRON STAR RADIUS MEASUREMENTS

    International Nuclear Information System (INIS)

    Elshamouty, K. G.; Heinke, C. O.; Morsink, S. M.; Stevens, A. L.; Bogdanov, S.

    2016-01-01

    Fitting the thermal X-ray spectra of neutron stars (NSs) in quiescent X-ray binaries can constrain the masses and radii of NSs. The effect of undetected hot spots on the spectrum, and thus on the inferred NS mass and radius, has not yet been explored for appropriate atmospheres and spectra. A hot spot would harden the observed spectrum, so that spectral modeling tends to infer radii that are too small. However, a hot spot may also produce detectable pulsations. We simulated the effects of a hot spot on the pulsed fraction and spectrum of the quiescent NSs X5 and X7 in the globular cluster 47 Tucanae, using appropriate spectra and beaming for hydrogen atmosphere models, incorporating special and general relativistic effects, and sampling a range of system angles. We searched for pulsations in archival Chandra HRC-S observations of X5 and X7, placing 90% confidence upper limits on their pulsed fractions below 16%. We use these pulsation limits to constrain the temperature differential of any hot spots, and to then constrain the effects of possible hot spots on the X-ray spectrum and the inferred radius from spectral fitting. We find that hot spots below our pulsation limit could bias the spectroscopically inferred radius downward by up to 28%. For Cen X-4 (which has deeper published pulsation searches), an undetected hot spot could bias its inferred radius downward by up to 10%. Improving constraints on pulsations from quiescent LMXBs may be essential for progress in constraining their radii.

  9. MODEL ATMOSPHERES FOR X-RAY BURSTING NEUTRON STARS

    International Nuclear Information System (INIS)

    Medin, Zach; Fontes, Christopher J.; Fryer, Chris L.; Hungerford, Aimee L.; Steinkirch, Marina von; Calder, Alan C.

    2016-01-01

    The hydrogen and helium accreted by X-ray bursting neutron stars is periodically consumed in runaway thermonuclear reactions that cause the entire surface to glow brightly in X-rays for a few seconds. With models of the emission, the mass and radius of the neutron star can be inferred from the observations. By simultaneously probing neutron star masses and radii, X-ray bursts (XRBs) are one of the strongest diagnostics of the nature of matter at extremely high densities. Accurate determinations of these parameters are difficult, however, due to the highly non-ideal nature of the atmospheres where XRBs occur. Observations from X-ray telescopes such as RXTE and NuStar can potentially place strong constraints on nuclear matter once uncertainties in atmosphere models have been reduced. Here we discuss current progress on modeling atmospheres of X-ray bursting neutron stars and some of the challenges still to be overcome.

  10. MODEL ATMOSPHERES FOR X-RAY BURSTING NEUTRON STARS

    Energy Technology Data Exchange (ETDEWEB)

    Medin, Zach; Fontes, Christopher J.; Fryer, Chris L.; Hungerford, Aimee L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Steinkirch, Marina von; Calder, Alan C. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)

    2016-12-01

    The hydrogen and helium accreted by X-ray bursting neutron stars is periodically consumed in runaway thermonuclear reactions that cause the entire surface to glow brightly in X-rays for a few seconds. With models of the emission, the mass and radius of the neutron star can be inferred from the observations. By simultaneously probing neutron star masses and radii, X-ray bursts (XRBs) are one of the strongest diagnostics of the nature of matter at extremely high densities. Accurate determinations of these parameters are difficult, however, due to the highly non-ideal nature of the atmospheres where XRBs occur. Observations from X-ray telescopes such as RXTE and NuStar can potentially place strong constraints on nuclear matter once uncertainties in atmosphere models have been reduced. Here we discuss current progress on modeling atmospheres of X-ray bursting neutron stars and some of the challenges still to be overcome.

  11. The Mars Hopper: Development, Simulation and Experimental Validation of a Radioisotope Exploration Probe for the Martian Surface

    Energy Technology Data Exchange (ETDEWEB)

    Nathan D. Jerred; Spencer Cooley; Robert C. O' Brien; Steven D. Howe; James E. O' Brien

    2012-09-01

    An advanced exploration probe has been proposed by the Center for Space Nuclear Research (CSNR) to acquire detailed data from the Martian surface and subsurface, ‘hop’ large distances to multiple sites in short periods of time and perform this task repeatedly. Although several similar flying vehicles have been proposed utilizing various power sources and complex designs, e.g. solar-electric and chemical-based, the CSNR’s Mars Hopper is based on a radioisotope thermal rocket (RTR) concept. The Mars Hopper’s design relies on the high specific energies [J/kg] of radioisotopes and enhances their low specific power [W/kg] through the use of a thermal capacitance material to store thermal energy over time. During operation, the RTR transfers the stored thermal energy to a flowing gas, which is then expanded through a converging-diverging nozzle, producing thrust. Between flights, the platform will have ample time to perform in-depth science at each location while the propellant tanks and thermal capacitor recharge. Recharging the propellant tanks is accomplished by sublimation freezing of the ambient CO2 atmosphere with a cryocooler, followed by heating and pressurization to yield a liquid storage state. The proposed Mars Hopper will undergo a ballistic flight, consuming the propellant in both ascent and descent, and by using multiple hopper platforms, information can be gathered on a global scale, enabling better resource resolution and providing valuable information for a possible Mars sample-return mission. The CSNR, collaborating with the Idaho National Laboratory (INL) and three universities (University of Idaho, Utah State University and Oregon State University), has identified key components and sub-systems necessary for the proposed hopper. Current project activities include the development of a lab-scale prototypic Mars Hopper and test facility, along with computational fluid dynamics (CFD)/thermal-hydraulic models to yield a better understanding of the

  12. In-plane conductance of thin films as a probe of surface chemical environment: Adsorbate effects on film electronic properties of indium tin oxide and gold

    Science.gov (United States)

    Swint, Amy Lynn

    Changes in the in-plane conductance of conductive thin films are observed as a result of chemical adsorption at the surface. Reaction of the indium tin oxide (ITO) surface with Bronsted acids (bases) leads to increases (decreases) in its in-plane conductance as measured by a four-point probe configuration. The conductance varies monotonically with pH suggesting that the degree of surface protonation or hydroxylation controls the surface charge density, which in turn affects the width of the n-type depletion layer, and ultimately the in-plane conductance. Measurements at constant pH with a series of tetraalkylammonium hydroxide species of varying cation size indicate that surface dipoles also affect ITO conductance by modulating the magnitude of the surface polarization. Modulating the double layer with varying aqueous salt solutions also affects ITO conductance, though not to the same degree as strong Bronsted acids and bases. Solvents of varying dielectric constant and proton donating ability (ethanol, dimethylformamide) decrease ITO conductance relative to H2O. In addition, changing solvent gives rise to thermally-derived conductance transients, which result from exothermic solvent mixing. The self-assembly of alkanethiols at the surface increases the conductance of ITO films, most likely through carrier population effects. In all cases examined the combined effects of surface charge, adsorbed dipole layer magnitude and carrier injection are responsible for altering the ITO conductance. Besides being directly applicable to the control of electronic properties, these results also point to the use of four-point probe resistance measurements in condensed phase sensing applications. Ultrasensitive conductance-based gas phase sensing of organothiol adsorption to gold nanowires is accomplished with a limit of detection in the 105 molecule range. Further refinement of the inherently low noise resistance measurement may lead to observation of single adsorption events at

  13. Electrical resistivity probes

    Science.gov (United States)

    Lee, Ki Ha; Becker, Alex; Faybishenko, Boris A.; Solbau, Ray D.

    2003-10-21

    A miniaturized electrical resistivity (ER) probe based on a known current-voltage (I-V) electrode structure, the Wenner array, is designed for local (point) measurement. A pair of voltage measuring electrodes are positioned between a pair of current carrying electrodes. The electrodes are typically about 1 cm long, separated by 1 cm, so the probe is only about 1 inch long. The electrodes are mounted to a rigid tube with electrical wires in the tube and a sand bag may be placed around the electrodes to protect the electrodes. The probes can be positioned in a borehole or on the surface. The electrodes make contact with the surrounding medium. In a dual mode system, individual probes of a plurality of spaced probes can be used to measure local resistance, i.e. point measurements, but the system can select different probes to make interval measurements between probes and between boreholes.

  14. Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit.

    Science.gov (United States)

    El-Jaby, Samy; Richardson, Richard B

    2015-07-01

    Occupational exposures from ionizing radiation are currently regulated for airline travel (Earth orbit (∼300-400 km). Aircrew typically receive between 1 and 6 mSv of occupational dose annually, while aboard the International Space Station, the area radiation dose equivalent measured over just 168 days was 106 mSv at solar minimum conditions. It is anticipated that space tourism vehicles will reach suborbital altitudes of approximately 100 km and, therefore, the annual occupational dose to flight crew during repeated transits is expected to fall somewhere between those observed for aircrew and astronauts. Unfortunately, measurements of the radiation environment at the high altitudes reached by suborbital vehicles are sparse, and modelling efforts have been similarly limited. In this paper, preliminary MCNPX radiation transport code simulations are developed of the secondary neutron flux profile in air from surface altitudes up to low Earth orbit at solar minimum conditions and excluding the effects of spacecraft shielding. These secondary neutrons are produced by galactic cosmic radiation interacting with Earth's atmosphere and are among the sources of radiation that can pose a health risk. Associated estimates of the operational neutron ambient dose equivalent, used for radiation protection purposes, and the neutron effective dose equivalent that is typically used for estimates of stochastic health risks, are provided in air. Simulations show that the neutron radiation dose rates received at suborbital altitudes are comparable to those experienced by aircrew flying at 7 to 14 km. We also show that the total neutron dose rate tails off beyond the Pfotzer maximum on ascension from surface up to low Earth orbit. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  15. Neutron and synchrotron probes in the development of Co-Re-based alloys for next generation gas turbines with an emphasis on the influence of boron additives

    Czech Academy of Sciences Publication Activity Database

    Mukherji, D.; Gilles, R.; Karge, L.; Strunz, Pavel; Beran, Přemysl; Eckerlebe, H.; Stark, A.; Szentmiklosi, L.; Macsik, Z.; Schumacher, G.; Zizak, I.; Hofmann, M.; Hoelzel, M.; Rösler, J.

    2014-01-01

    Roč. 47, č. 4 (2014), s. 1417-1430 ISSN 0021-8898 R&D Projects: GA ČR GB14-36566G EU Projects: European Commission(XE) 283883 - NMI3-II Institutional support: RVO:61389005 Keywords : high-temperature alloys * In-situ neutron * FRM-II Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.720, year: 2014

  16. Neutron energy spectrum determination near the surface on the JET vacuum vessel using the multifoil activation technique

    Energy Technology Data Exchange (ETDEWEB)

    Pillon, M.; Jarvis, O.N.; Conroy, S. (Associazione EURATOM-ENEA sulla Fusione, Frascati (Italy) JET Joint Undertaking, Abingdonm Oxon (U.K.) Imperial College of Science, Technology and Medicine, London (U.K.))

    1990-03-01

    The activation of foils of zinc, indium, aluminium, copper and magnesium has been used as a means of examining the energy spectrum of neutrons produced by discharges in the Joint European Torus (JET). Several threshold reactions have been used together with a least-squares unfolding code to determine the 2.5 and 14 MeV neutron yields produced by the JET plasma. The analysis shows that the energy spectrum produced by downscattered neutrons is satisfactorily calculated with the MCNP neutron transport code.

  17. Pulsed neutron uranium borehole logging with prompt fission neutrons

    International Nuclear Information System (INIS)

    Bivens, H.M.; Smith, G.W.; Jensen, D.H.

    1976-01-01

    The gross count natural gamma log normally used for uranium borehole logging is seriously affected by disequilibrium. Methods for the direct measurement of uranium, such as neutron logging, which are not affected by disequilibrium have been the object of considerable effort in recent years. This paper describes a logging system for uranium which uses a small accelerator to generate pulses of 14 MeV neutrons to detect and assay uranium by the measurement of prompt fission neutrons in the epithermal energy range. After an initial feasibility study, a prototype logging probe was built for field evaluation which began in January 1976. Physical and operational characteristics of the prototype probe, the neutron tube-transformer assembly, and the neutron tube are described. In logging operations, only the epithermal prompt fission neutrons detected between 250 microseconds to 2500 microseconds following the excitation neutron pulse are counted. Comparison of corrected neutron logs with the conventional gross count natural gamma logs and the chemical assays of cores from boreholes are shown. The results obtained with this neutron probe clearly demonstrate its advantages over the gross count natural gamma log, although at this time the accuracy of the neutron log assay is not satisfactory under some conditions. The necessary correction factors for various borehole and formation parameters are being determined and, when applied, should improve the assay accuracy

  18. Monte carlo calculation of the neutron effective dose rate at the outer surface of the biological shield of HTR-10 reactor

    International Nuclear Information System (INIS)

    Remetti, Romolo; Andreoli, Giulio; Keshishian, Silvina

    2012-01-01

    Highlights: ► We deal with HTR-10, that is a helium-cooled graphite-moderated pebble bed reactor. ► We carried out Monte Carlo simulation of the core by MCNP5. ► Extensive use of MCNP5 variance reduction methods has been done. ► We calculated the trend of neutron flux within the biological shield. ► We calculated neutron effective dose at the outer surface of biological shield. - Abstract: Research on experimental reactors, such as HTR-10, provide useful data about potentialities of very high temperature gas-cooled reactors (VHTR). The latter is today rated as one of the six nuclear reactor types involved in the Generation-IV International Forum (GIF) Initiative. In this study, the MCNP5 code has been employed to evaluate the neutron radiation trend vs. the biological shield's thickness and to calculate the neutron effective dose rate at the outer surface. The reactor's geometry has been completely modeled by means of lattices and universes provided by MCNP, even though some approximations were required. Monte Carlo calculations have been performed by means of a simple PC and, as a consequence, in order to obtain acceptable run times, it was made an extensive recourse to variance reduction methods.

  19. Measuring probe for a nuclear reactor

    International Nuclear Information System (INIS)

    Overhoff, T.

    1976-01-01

    A coaxial cable is helically wound into two concentric coils, forming the one end of the probe. At the other end of the probe, the inner conductor's ends are wired to the outer conducter's two extremities by a conductor made of a material with low neutron and gamma interaction cross-section. The direct current produced by this self-powered detector is frequency filtered in order to separate the contributions of the neutron induced secondary-electrons from the photo-electrons, and from the thermally excited conduction electrons. Neutron and gamma fluxes, as well as temperature are therefore determined by using a single probe. (RW) [de

  20. Thermal neutron imaging in an active interrogation environment

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  1. Electron-accepting surface properties of ceria-(praseodymia)-zirconia solids modified by Y 3+ or La 3+ studied by paramagnetic probe method

    Science.gov (United States)

    Ikryannikova, Larisa N.; Markaryan, Goar L.; Kharlanov, Andrey N.; Lunina, Elena V.

    2003-02-01

    EPR paramagnetic probe method with 2,2,6,6-tetramethylpiperidin- N-oxyl (TEMPO) as a probe has been applied to study of electron-accepting properties of the surface of (Y, La 0.1)Ce xZr 1- xO 2- y ( x=0.1-0.7), Y 0.1Pr 0.3Zr 0.6O 2- y and Y 0.1Pr 0.15Ce 0.15Zr 0.7O 2- y mixed oxides. Two types of acceptor sites—coordinatively unsaturated (cus) cations Zr 4+ and Ce 4+—have been revealed on the CeO 2-ZrO 2 surface after thermovacuum treatment (820 K). The relative amounts and "strength" of these centers were evaluated on the basis of EPR spectra analysis. An introduction of trivalent Y 3+ or La 3+ cations reduces the amount of electron-acceptor sites belonging to cerium cations, stabilizing ones as Ce 3+. A formation of very strong electron-accepting sites (Pr 4+ cus cations) able to form charge transfer complexes with adsorbed TEMPO on the surface of praseodymia-containing samples after thermovacuum treatment was found out. At the same time electron-accepting ability of Zr 4+ cationic sites on Y 0.1Pr 0.3Zr 0.6O 2- y and Y 0.1Pr 0.15Ce 0.15Zr 0.7O 2- y surfaces decreases in comparison with ceria-zirconia one. The generally used IR spectroscopy technique with CO as a probe molecule appeared to be considerably less informative for such systems characterization, due to their high catalytic activity to carbon monoxide. A formation of paramagnetic Zr 3+ ions in ceria-zirconia mixed oxides has been investigated by EPR spectroscopy technique. The different states of this paramagnetic ion are realized in the complex oxides depending on Ce/Zr ratio.

  2. Exploring the potential of the cosmic-ray neutron method to measure interception storage dynamics

    Science.gov (United States)

    Jakobi, Jannis; Bogena, Heye; Huisman, Johan Alexander; Diekkrüger, Bernd; Vereecken, Harry

    2017-04-01

    Cosmic-ray neutron soil moisture probes are an emerging technology that relies on the negative correlation between near-surface fast neutron counts and soil moisture content. Hydrogen atoms in the soil, which are mainly present as water, moderate the secondary neutrons on the way back to the surface. Any application of this method needs to consider the sensitivity of the neutron counts to additional sources of hydrogen (e.g. above- and below-ground biomass, humidity of the lower atmosphere, lattice water of the soil minerals, organic matter and water in the litter layer, intercepted water in the canopy, and soil organic matter). In this study, we analyzed the effects of canopy-intercepted water on the cosmic-ray neutron counts. For this, an arable field cropped with sugar beet was instrumented with several cosmic-ray neutron probes and a wireless sensor network with more than 140 in-situ soil moisture sensors. Additionally rainfall interception was estimated using a new approach coupling throughfall measurements and leaf wetness sensors. The derived interception storage was used to correct for interception effects on cosmic ray neutrons to enhance soil water content prediction. Furthermore, the potential for a simultaneous prediction of above- and below-ground biomass, soil moisture and interception was tested.

  3. Development of neutron detector using sensor type surface barrier with (n,p) and (n,α) converters

    International Nuclear Information System (INIS)

    Madi Filho, Tufic

    1999-01-01

    A Si semiconductor detector, surface barrier type, with a slim film of a converter material capable to produce charged particles was used as a sensor of neutrons in an environment of a zero power reactor. Two types of converters were used to improve the detection efficiency: (1) the polyethylene, n(CH 2 ), which produces recoil protons from the (n,p) interaction and, (2) the 10 B which generates a particle from the (n,alpha) reaction. The optimal thickness of those converters was determined experimentally and specifically for the polyethylene a mathematical model R(ips) = ε p · N 0 ·(1-e -Σ·Χ ) ·e -μ ·Χ + ε n · N 0 · -Σ · Χ was used to fit to the experimental data. For the polyethylene converter the thickness was of 0.058 cm (62.64 mg.cm -2 ) while for the 10 B it was equal to 6.55 [μm (1.54 mg.cm -2 ). The converter of polyethylene or 10 B improved the detection efficiency to a factor of 4.7 and 3.0 respectively. The comparison of the spectrum of the background radiation with the spectra of the recoil protons and the a radiation from the 10 B it was concluded that the polyethylene presented better performance than the 10 B converter. (author)

  4. An inexpensive and simple method for thermally stable immobilization of DNA on an unmodified glass surface: UV linking of poly(T)10-poly(C)10-tagged DNA probes

    DEFF Research Database (Denmark)

    Guðnason, Haukur; Dufva, Hans Martin; Bang, Dang Duong

    2008-01-01

    be linked by UV light irradiation onto a plain, unmodified glass surface. Probes immobilized onto unmodified glass microscope slides performed similarly to probes bound to commercial amino-silane-coated slides and had comparable detection limits. The TC-tagged probes linked to unmodified glass did not show...... any significant decrease in hybridization performance after a 20 min incubation in water at 100 degrees C prior to rehybridization, indicating a covalent bond between the TC tag and unmodified glass. The probes were used in thermal minisequencing cycling reactions. Furthermore, the TC tag improved...

  5. Neutron scattering—The key characterization tool for nanostructured magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Fitzsimmons, M.R., E-mail: fitz@lanl.gov [Los Alamos National Laboratory (United States); Schuller, Ivan K. [University of California, San Diego (United States)

    2014-01-15

    The novel properties of materials produced using nanoscale manufacturing processes often arise from interactions across interfaces between dissimilar materials. Thus, to characterize the structure and magnetism of nanoscale materials demands tools with interface specificity. Neutron scattering has long been known to provide unique and quantitative information about nuclear and magnetic structures of bulk materials. Moreover, the specialty techniques of polarized neutron reflectometry and small angle neutron scattering (SANS) with polarized neutron beams and polarization analysis, are ideally and often uniquely suited to studies of nanostructured magnetic materials. Since neutron scattering is a weakly interacting probe, it gives quantifiable and easily-interpreted information on properties of statistically representative quantities of bulk, thin film and interfacial materials. In addition, neutron scattering can provide information to complement that obtained with bulk probes (magnetization, Kerr effect) or surface measurements obtained with scanning probe microscopy or resonant soft x-ray scattering. The straightforward interpretation and the simultaneous availability of structural information, make neutron scattering the technique of choice for the structural and physical characterization of many novel materials, especially those with buried interfaces, ones allowing for isotopic substitutions to decorate buried interfaces, or cases where the magnetic response to an external stimulus can be measured. We describe recent applications of neutron scattering to important thin film materials systems and future opportunities. Unquestionably, neutron scattering has played a decisive role in the development and study of new emergent phenomena. We argue with the advent of new techniques in neutron scattering and sample environment, neutron scattering's role in such studies will become even more dominant. In particular, neutron scattering will clarify and distinguish

  6. Traversing incore probe device

    International Nuclear Information System (INIS)

    Yoshioka, Michiko.

    1985-01-01

    Purpose: To measure the neutron flux distribution in the reactor core always at a high accuracy. Constitution: A nuclear fission ionizing chamber type detector is disposed at the end of a cable for sending a detection signal of a traversing incore probe device and, further, a gamma-ray ionizing chamber type detector is connected in adjacent therewith and a selection circuit for selecting both of the detection signals and inputting them to a display device is disposed. Then, compensation for the neutron monitors is conducted by the gamma-ray ionizing chamber type detector during normal operation in which control rods are not driven and the positioning is carried out by the nuclear fission ionizing chamber type detector. Furthermore, both of the compensation for the neutron detector and the positioning are carried out by the nuclear fission ionizing chamber type detector upon starting where the control rods are driven. (Sekiya, K.)

  7. Probing the semi-magicity of $^{68}$Ni via the $^{66}$Ni(t,p)$^{68}$Ni two-neutron transfer reaction in inverse kinematics

    CERN Document Server

    AUTHOR|(CDS)2079390; Van Duppen, Piet

    The region around the nucleus $^{68}$Ni, with a shell closure for its protons at Z=28 and a harmonic oscillator shell gap for its neutrons at N=40, has drawn considerable interest over the past decades. $^{68}$Ni has properties that are typical for a doubly-magic nucleus, such as a high excitation energy and low B($E2:2^{+} \\rightarrow 0^{+}$) transition probability for the first excited 2$^{+}$ level and a 0$^{+}$ level as the first excited state. However, it has been suggested that the magic properties of $^{68}$Ni arise due to the fact that the N=40 separates the negative parity $pf$-shell from the positive parity 1$g_{9/2}$ orbital, and indeed, recent mass measurements have not revealed a clear N = 40 energy gap. Despite all additional information that was acquired over the last decade the specific role of the N=40 is not yet understood and a new experimental approach to study $^{68}$Ni was proposed. Namely, a two-neutron transfer reaction on $^{66}$Ni to characterize and disentangle the structure of the ...

  8. Structure-dependent vibrational dynamics of Mg(BH 4 ) 2 polymorphs probed with neutron vibrational spectroscopy and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrievska, Mirjana; White, James L.; Zhou, Wei; Stavila, Vitalie; Klebanoff, Leonard E.; Udovic, Terrence J.

    2016-01-01

    The structure-dependent vibrational properties of different Mg(BH4)2 polymorphs (..alpha.., ..beta.., ..gamma.., and ..delta.. phases) were investigated with a combination of neutron vibrational spectroscopy (NVS) measurements and density functional theory (DFT) calculations, with emphasis placed on the effects of the local structure and orientation of the BH4- anions. DFT simulations closely match the neutron vibrational spectra. The main bands in the low-energy region (20-80 meV) are associated with the BH4- librational modes. The features in the intermediate energy region (80-120 meV) are attributed to overtones and combination bands arising from the lower-energy modes. The features in the high-energy region (120-200 meV) correspond to the BH4- symmetric and asymmetric bending vibrations, of which four peaks located at 140, 142, 160, and 172 meV are especially intense. There are noticeable intensity distribution variations in the vibrational bands for different polymorphs. This is explained by the differences in the spatial distribution of BH4- anions within various structures. An example of the possible identification of products after the hydrogenation of MgB2, using NVS measurements, is presented. These results provide fundamental insights of benefit to researchers currently studying these promising hydrogen-storage materials.

  9. Development of probes for bioanalytic applications of the surface-enhanced Raman scattering; Entwicklung neuer Sonden fuer bioanalytische Anwendungen der oberflaechenverstaerkten Raman-Streuung

    Energy Technology Data Exchange (ETDEWEB)

    Matschulat, Andrea Isabel

    2011-07-01

    Surface-enhanced Raman scattering (SERS) has been established as a versatile tool for probing and labeling in analytical applications, based on the vibrational spectra of samples as well as label molecules in the proximity of noble metal nanostructures. The aim of this work was the construction of novel SERS hybrid probes. The hybrid probes consisted of Au and Ag nanoparticles and reporter molecules, as well as a targeting unit. The concept for the SERS hybrid probe design was followed by experiments comprising characterization techniques such as UV/Vis-spectroscopy (UV/Vis), Transmission electron microscopy (TEM) and Dynamic Light Scattering (DLS), respectively. SERS experiments were performed for studying and optimizing the plasmonic properties of nanoparticles with respect to their enhancement capabilities. The SERS-probes had to meet following requirements: biocompatibility, stability in physiological media, and enhancement of Raman-signals from Raman reporter molecules enabling the identification of different probes even in a complex biological environment. Au and Ag nanoaggregates were found to be the most appropriate SERS substrates for the hybrid probe design. The utilization of Raman reporters enabled the identification of different SERS probes in multiplexing experiments. In particular, the multiplexing capability of ten various reporter molecules para-aminobenzenethiol, 2-naphthalenethiol, crystal violet, rhodamine (B) isothiocyanate, fluorescein isothiocyanate, 5,5'dithiobis(2-nitrobenzoic acid), para-mercaptobenzoic acid, acridine orange, safranine O und nile blue was studied using NIR-SERS excitation. As demonstrated by the results the reporters could be identified through their specific Raman signature even in the case of high structural similarity. Chemical separation analysis of the reporter signatures was performed in a trivariate approach, enabling the discrimination through an automated calculation of specific band ratios. The trivariate

  10. Pulsed neutron generator for logging

    International Nuclear Information System (INIS)

    Thibideau, F.D.

    1977-01-01

    A pulsed neutron generator for uranium logging is described. This generator is one component of a prototype uranium logging probe which is being developed by SLA to detect, and assay, uranium by borehole logging. The logging method is based on the measurement of epithermal neutrons resulting from the prompt fissioning of uranium from a pulsed source of 17.6 MeV neutrons. An objective of the prototype probe was that its diameter not exceed 2.75 inches, which would allow its use in conventional rotary drill holes of 4.75-inch diameter. This restriction limited the generator to a maximum 2.375-inch diameter. The performance requirements for the neutron generator specified that it operate with a nominal output of 5 x 10 6 neutrons/pulse at up to 100 pulses/second for a one-hour period. The development of a neutron generator meeting the preliminary design goals was completed and two prototype models were delivered to SLA. These two generators have been used by SLA to log a number of boreholes in field evaluation of the probe. The results of the field evaluations have led to the recommendation of several changes to improve the probe's operation. Some of these changes will require additional development effort on the neutron generator. It is expected that this work will be performed during 1977. The design and operation of the first prototype neutron generators is described

  11. Measurement of plasma-surface energy fluxes in an argon rf-discharge by means of calorimetric probes and fluorescent microparticles

    International Nuclear Information System (INIS)

    Maurer, H. R.; Kersten, H.; Hannemann, M.; Basner, R.

    2010-01-01

    Measured energy influx densities toward a tungsten dummy substrate in an argon rf-plasma are presented and a model for the description of the energy influx density based on plasma parameters, which have been obtained by Langmuir probe measurements, is applied. Furthermore, temperature measurements of microparticles are presented, which are confined in the plasma sheath. An extension of the model is developed for the description of the energy influx density to the particles. The comparison of model and experimental results offer the possibility to obtain an improved understanding of plasma-surface interactions.

  12. Probing surface states in PbS nanocrystal films using pentacene field effect transistors: controlling carrier concentration and charge transport in pentacene.

    Science.gov (United States)

    Park, Byoungnam; Whitham, Kevin; Bian, Kaifu; Lim, Yee-Fun; Hanrath, Tobias

    2014-12-21

    We used a bilayer field effect transistor (FET) consisting of a thin PbS nanocrystals (NCs) film interfaced with vacuum-deposited pentacene to probe trap states in NCs. We interpret the observed threshold voltage shift in context of charge carrier trapping by PbS NCs and relate the magnitude of the threshold voltage shift to the number of trapped carriers. We explored a series of NC surface ligands to modify the interface between PbS NCs and pentacene and demonstrate the impact of interface chemistry on charge carrier density and the FET mobility in a pentacene FET.

  13. Contraband detection with fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Buffler, Andy E-mail: abuffler@science.uct.ac.za

    2004-11-01

    Recent terror events and the increase in the trade of illicit drugs have fuelled the exploration of the use of fast neutrons as probes for the detection of hidden contraband, especially explosives, in packages ranging in size from small mail items to cargo containers. The various approaches using fast neutrons for contraband detection, presently under development, are reviewed. The role that a neutron system might play in the non-intrusive interrogation of airline luggage is discussed.

  14. Localized excitation of magnetostatic surface spin waves in yttrium iron garnet by shorted coaxial probe detected via spin pumping and rectification effect

    International Nuclear Information System (INIS)

    Soh, Wee Tee; Ong, C. K.; Peng, Bin

    2015-01-01

    We demonstrate the localized excitation and dc electrical detection of magnetostatic surface spin waves (MSSWs) in yttrium iron garnet (YIG) by a shorted coaxial probe. Thin films of NiFe and Pt are patterned at different regions onto a common bulk YIG substrate. A shorted coaxial probe is used to excite spin precession locally near various patterned regions. The dc voltages across the corresponding regions are recorded. For excitation of the Pt regions, the dc voltage spectra are dominated by the spin pumping of MSSWs from YIG, where various modes can be clearly distinguished. For the NiFe region, it is also found that spin pumping from MSSWs generated in YIG dominated the spectra, indicating that the spin pumped currents are dissipated into charge currents via the inverse Spin Hall effect (ISHE) in NiFe. For all regions, dc signals from YIG MSSWs are observed to be much stronger than the ferromagnetic resonance (FMR) uniform mode, likely due to the nature of the microwave excitation. The results indicate the potential of this probe for microwave imaging via dc detection of spin dynamics in continuous and patterned films

  15. Effect of SP-C on surface potential distribution in pulmonary surfactant: Atomic force microscopy and Kelvin probe force microscopy study

    International Nuclear Information System (INIS)

    Hane, Francis; Moores, Brad; Amrein, Matthias; Leonenko, Zoya

    2009-01-01

    The air-lung interface is covered by a molecular film of pulmonary surfactant (PS). The major function of the film is to reduce the surface tension of the lung's air-liquid interface, providing stability to the alveolar structure and reducing the work of breathing. Earlier we have shown that function of bovine lipid extract surfactant (BLES) is related to the specific molecular architecture of surfactant films. Defined molecular arrangement of the lipids and proteins of the surfactant film also give rise to a local highly variable electrical surface potential of the interface. In this work we investigated a simple model of artificial lung surfactant consisting of DPPC, eggPG, and surfactant protein C (SP-C). Effects of surface compression and the presence of SP-C on the monolayer structure and surface potential distribution were investigated using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We show that topography and locally variable surface potential of DPPC-eggPG lipid mixture are similar to those of pulmonary surfactant BLES in the presence of SP-C and differ in surface potential when SP-C is absent.

  16. Neutron is a marvelous probe to see the living things as it is alive. Real time and in-situ observation on living polymerization

    International Nuclear Information System (INIS)

    Koizumi, Satoshi

    2011-01-01

    Small-angle neutron scattering was employed in order to perform a real time and in-situ observation on a polymerization-induced self-assembly process in in-vivo or in-vitro systems; precise living anionic polymerization of poly-styrene-b-polyisoprene, pre-irradiation radical polymerization of polystyrene onto a polytetrafluoroethylene film, and microbial or enzymatic polymerization of cellulose. The aim of these studies is to clarify self-organizations of macro-molecular assemblies appeared in open non-equilibrium systems, which are exposed to external energy and mass flows induced by chemical reactions. The open non-equilibrium systems are believed to be important for understanding pattern formations not only in materials processing in industry but also in living things. Small-angle scattering observed for the systems was investigated according to the methods established for condensed matter physics (fractal and computational analyses), bridging with synthetic chemistry and molecular biology. (author)

  17. Visualization and measurement of gas-liquid metal two-phase flow with large density difference using thermal neutrons as microscopic probes

    International Nuclear Information System (INIS)

    Saito, Y.; Hibiki, T.; Mishima, K.; Nishihara, H.; Yamamoto, A.; Kanda, K.; Tobita, Y.; Konishi, K.; Matsubayashi, M.

    1998-01-01

    In a core melt accident of a fast breeder reactor there is a possibility of boiling of fuel-steel mixture in the containment pool. In relation to safety evaluation on severe accident, it is indispensable to evaluate the recriticality of melted core. Gas-liquid two-phase flow with a large density difference is formed due to the boiling of fuel-steel mixture. Although the large density difference may affect the basic characteristics of two-phase flow, little work has been performed so far on two-phase flow with large density difference has not been performed well. In this study, visualization and void fraction measurement of gas-liquid metal two-phase flow were performed by using neutron radiography. The effect of the large density difference between gas and liquid phases on the basic flow characteristics of two-phase flow was clarified. (author)

  18. Penning-trap mass spectrometry of neutron-rich copper isotopes for probing the Z = 28 and N = 50 shell closures

    CERN Multimedia

    Manea, V

    We propose to perform a Penning-trap mass measurement of $^{79}$Cu. This exotic N = 50 isotone is the last frontier before the doubly-magic $^{78}$Ni and will greatly improve our knowledge of shell evolution. In the same run, we propose $^{77-78}$Cu mass measurements, as well as the search for a possible isomer in $^{76m}$Cu. The data will help to clarify the structure of the odd proton in the Cu isotopes, the influence on the Z = 28 proton core of the νg$_{9/2}$ orbital filling and the impact of the proton-neutron residual interaction on the strength of the N = 50 shell closure.

  19. Neutrons in nuclear physics from Billiard Balls to quark-gluon structure

    International Nuclear Information System (INIS)

    Annand, J. R. M.

    2002-01-01

    Neutrons and protons are the main building blocks of atomic nuclei and neutrons have been used to probe nuclear structure since the pioneering days of nuclear physics. As strongly interacting hadrons they have a high probability of reaction and, being uncharged, they are unaffected by the nuclear Coulomb field. Neutron scattering for example has been used to determine nuclear sizes and shapes. However the strong interaction inhibits the neutron from penetrating the surface skin of the nucleus and to gain information on the interior a relatively weakly interacting probe such as a photon or electron is superior.As the energies of electron accelerators have increased, shorter distances may be probed, until at a photon momentum of ∼200 MeV/c the reduced wavelength is 1 fm, roughly the dimension of the neutron or proton. From this point one starts to become sensitive to the internal structure. Until recently most experiments have concentrated on the proton as a hydrogen target is experimentally straightforward. There is of course no free neutron target, but with an improved understanding of how nuclear binding affects the neutron embedded in deuterium or helium-3, these materials may be considered as effective neutron targets. The extra information obtained from examining an up-down-down-quark neutron, as opposed to an up-up-down-quark proton, will be vital to achieve a full understanding of the ways in which elementary quarks and gluons interact to make composite hadrons. New results from the MAMI accelerator in Germany are presented and an extension of these measurements at Jefferson Laboratory in the USA is previewed.As well as being pivotal to the development of fundamental nuclear physics, neutrons have immense technological importance. Many of the early neutron scattering experiments were driven by a need to understand nuclear fission processes for power generation or weapons production, but neutron beams have also been widely used in medicine for the treatment

  20. Polarized neutrons

    International Nuclear Information System (INIS)

    Williams, W.G.

    1988-01-01

    The book on 'polarized neutrons' is intended to inform researchers in condensed matter physics and chemistry of the diversity of scientific problems that can be investigated using polarized neutron beams. The contents include chapters on:- neutron polarizers and instrumentation, polarized neutron scattering, neutron polarization analysis experiments and precessing neutron polarization. (U.K.)

  1. Surface potential measurement on contact resistance of amorphous-InGaZnO thin film transistors by Kelvin probe force microscopy

    Science.gov (United States)

    Han, Zhiheng; Xu, Guangwei; Wang, Wei; Lu, Congyan; Lu, Nianduan; Ji, Zhuoyu; Li, Ling; Liu, Ming

    2016-07-01

    Contact resistance plays an important role in amorphous InGaZnO (a-IGZO) thin film transistors (TFTs). In this paper, the surface potential distributions along the channel have been measured by using Kelvin probe force microscopy (KPFM) on operating a-IGZO TFTs, and sharp potential drops at the edges of source and drain were observed. The source and drain contact resistances can be extracted by dividing sharp potential drops with the corresponding drain to source current. It is found that the contact resistances could not be neglected compared with the whole channel resistances in the a-IGZO TFT, and the contact resistances decrease remarkably with increasing gate biased voltage. Our results suggest that the contact resistances can be controlled by tuning the gate biased voltage. Moreover, a transition from gradual channel approximation to space charge region was observed through the surface potential map directly when TFT operating from linear regime to saturation regime.

  2. Neutron--neutron logging

    International Nuclear Information System (INIS)

    Allen, L.S.

    1977-01-01

    A borehole logging tool includes a steady-state source of fast neutrons, two epithermal neutron detectors, and two thermal neutron detectors. A count rate meter is connected to each neutron detector. A first ratio detector provides an indication of the porosity of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two epithermal neutron detectors. A second ratio detector provides an indication of both porosity and macroscopic absorption cross section of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two thermal neutron detectors. By comparing the signals of the two ratio detectors, oil bearing zones and salt water bearing zones within the formation being logged can be distinguished and the amount of oil saturation can be determined. 6 claims, 2 figures

  3. Determination of three-dimensional interfacial strain - A novel method of probing interface structure with X-ray Bragg-surface diffraction

    International Nuclear Information System (INIS)

    Sun, W.-C.; Chu, C.-H.; Chang, H.-C.; Wu, B.-K.; Chen, Y.-R.; Cheng, C.-W.; Chiu, M.-S.; Shen, Y.-C.; Wu, H.-H.; Hung, Y.-S.; Chang, S.-L.; Hong, M.-H.; Tang, M.-T.; Stetsko, Yu.P.

    2007-01-01

    A new X-ray diffraction technique is developed to probe structural variations at the interfaces between epitaxy thin films and single-crystal substrates. The technique utilizes three-wave Bragg-surface diffraction, where a symmetric Bragg reflection and an asymmetric surface reflection are involved. The propagation of the latter along the interfaces conveys structural information about the interfacial region between the substrate and epi-layers. The sample systems of Au/GaAs(001) are subject to the three-wave diffraction investigation using synchrotron radiation. The GaAs three-wave Bragg-surface diffractions (006)/(11-bar3) and (006)/(1-bar1-bar3), are employed. The images of the surface diffracted waves are recorded with an image plate. The obtained images show relative positions of diffraction spots near the image of the interfacial boundary, which give the variation of lattice constant along the surface normal and in-plane directions. With the aid of grazing-incidence diffraction, three-dimensional mapping of strain field at the interfaces is possible. Details about this diffraction technique and the analysis procedures are discussed

  4. Physical methods for studying minerals and solid materials: X-ray, electron and neutron diffraction; scanning and transmission electron microscopy; X-ray, electron and ion spectrometry

    International Nuclear Information System (INIS)

    Eberhart, J.-P.

    1976-01-01

    The following topics are discussed: theoretical aspects of radiation-matter interactions; production and measurement of radiations (X rays, electrons, neutrons); applications of radiation interactions to the study of crystalline materials. The following techniques are presented: X-ray and neutron diffraction, electron microscopy, electron diffraction, X-ray fluorescence analysis, electron probe microanalysis, surface analysis by electron emission spectrometry (ESCA and Auger electrons), scanning electron microscopy, secondary ion emission analysis [fr

  5. Surface polymerization of (3,4-ethylenedioxythiophene) probed by in situ scanning tunneling microscopy on Au(111) in ionic liquids.

    Science.gov (United States)

    Ahmad, Shahzada; Carstens, Timo; Berger, Rüdiger; Butt, Hans-Jürgen; Endres, Frank

    2011-01-01

    The electropolymerization of 3,4-ethylenedioxythiophene (EDOT) to poly(3,4-ethylenedioxythiophene) (PEDOT) was investigated in the air and water-stable ionic liquids 1-hexyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate [HMIm]FAP and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide [EMIm]TFSA. In situ scanning tunnelling microscopy (STM) results show that the electropolymerization of EDOT in the ionic liquid can be probed on the nanoscale. In contrast to present understanding, it was observed that the EDOT can be oxidised in ionic liquids well below its oxidation potential and the under potential growth of polymer was visualized by in situ STM. These results serve as the first study to confirm the under potential growth of conducting polymers in ionic liquids. Furthermore, ex situ microscopy measurements were performed. Quite a high current of 670 nA was observed on the nanoscale by conductive scanning force microscopy (CSFM).

  6. Visualization and measurement of gas-liquid metal two-phase flow with large density difference using thermal neutrons as microscopic probes

    International Nuclear Information System (INIS)

    Mishima, K.; Hibiki, T.; Saito, Y.; Nishihara, H.; Tobita, Y.; Konishi, K.; Matsubayashi, M.

    1999-01-01

    In a core melt accident of a fast breeder reactor, there is a possibility of boiling of the fuel-steel mixture in the containment pool. In relation to safety evaluation on severe accident, it is indispensable to evaluate the possibility of re-criticality of melted core. Gas-liquid two-phase flow with a large liquid-to-gas density ratio is formed due to the boiling of fuel-steel mixture. Although it is anticipated that the large density ratio may affect the basic characteristics of two-phase flow, little work has been performed so far on two-phase flow with a large liquid-to-gas density ratio. In this study, visualization and void fraction measurement of gas-liquid metal two-phase flow were performed by using neutron radiography and image processing techniques. Then, the effect of large density difference between gas and liquid phases on the basic flow characteristics of two-phase flow was clarified

  7. Structural and phase transition changes of sodium dodecyl sulfate micellar solution in alcohols probed by small-angle neutron scattering (SANS)

    Energy Technology Data Exchange (ETDEWEB)

    Putra, Edy Giri Rachman [Neutron Scattering Laboratory, National Nuclear Energy Agency of Indonesia (BATAN), Gedung 40 BATAN, Kawasan Puspiptek Serpong, Tangerang 15314 (Indonesia); Patriati, Arum [Neutron Scattering Laboratory, National Nuclear Energy Agency of Indonesia (BATAN), Gedung 40 BATAN, Kawasan Puspiptek Serpong, Tangerang 15314 (Indonesia); Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Gadjah Mada, Bulaksumur, Yogyakarta 55281, Indonesia giri@batan.go.id (Indonesia)

    2015-04-16

    Small-angle neutron scattering (SANS) measurements on 0.3M sodium dodecyl sulfate (SDS) micellar solutions have been performed in the presence of n-alcohols, from ethanol to decanol at different alcohol concentrations, 2–10 wt%. The ellipsoid micellar structure which occurred in the 0.3M SDS in aqueous solution with the size range of 30–50 Å has different behavior at various hydrocarbon chain length and concentration of alcohols. At low concentration and short chain-length of alcohols, such as ethanol, propanol, and butanol, the size of micelles reduced and had a spherical-like structure. The opposite effect occurred as medium to long chain alcohols, such as hexanol, octanol and decanol was added into the 0.3M SDS micellar solutions. The micelles structure changed to be more elongated in major axis and then crossed the critical phase transition from micellar solution into liquid crystal phase as lamellar structure emerged by further addition of alcohols. The inter-lamellar distances were also depending on the hydrocarbon chain length and concentration of alcohols. In the meantime, the persistent micellar structures occurred in addition of medium chain of n-alcohol, pentanol at all concentrations.

  8. Structural and phase transition changes of sodium dodecyl sulfate micellar solution in alcohols probed by small-angle neutron scattering (SANS)

    International Nuclear Information System (INIS)

    Putra, Edy Giri Rachman; Patriati, Arum

    2015-01-01

    Small-angle neutron scattering (SANS) measurements on 0.3M sodium dodecyl sulfate (SDS) micellar solutions have been performed in the presence of n-alcohols, from ethanol to decanol at different alcohol concentrations, 2–10 wt%. The ellipsoid micellar structure which occurred in the 0.3M SDS in aqueous solution with the size range of 30–50 Å has different behavior at various hydrocarbon chain length and concentration of alcohols. At low concentration and short chain-length of alcohols, such as ethanol, propanol, and butanol, the size of micelles reduced and had a spherical-like structure. The opposite effect occurred as medium to long chain alcohols, such as hexanol, octanol and decanol was added into the 0.3M SDS micellar solutions. The micelles structure changed to be more elongated in major axis and then crossed the critical phase transition from micellar solution into liquid crystal phase as lamellar structure emerged by further addition of alcohols. The inter-lamellar distances were also depending on the hydrocarbon chain length and concentration of alcohols. In the meantime, the persistent micellar structures occurred in addition of medium chain of n-alcohol, pentanol at all concentrations

  9. Surface studies of plasma processed Nb samples

    International Nuclear Information System (INIS)

    Tyagi, Puneet V.; Doleans, Marc; Hannah, Brian S.; Afanador, Ralph; Stewart, Stephen; Mammosser, John; Howell, Matthew P; Saunders, Jeffrey W; Degraff, Brian D; Kim, Sang-Ho

    2015-01-01

    Contaminants present at top surface of superconducting radio frequency (SRF) cavities can act as field emitters and restrict the cavity accelerating gradient. A room temperature in-situ plasma processing technology for SRF cavities aiming to clean hydrocarbons from inner surface of cavities has been recently developed at the Spallation Neutron Source (SNS). Surface studies of the plasma-processed Nb samples by Secondary ion mass spectrometry (SIMS) and Scanning Kelvin Probe (SKP) showed that the NeO_2 plasma processing is very effective to remove carbonaceous contaminants from top surface and improves the surface work function by 0.5 to 1.0 eV.

  10. Imaging of human vertebral surface using ultrasound RF data received at each element of probe for thoracic anesthesia

    Science.gov (United States)

    Takahashi, Kazuki; Taki, Hirofumi; Onishi, Eiko; Yamauchi, Masanori; Kanai, Hiroshi

    2017-07-01

    Epidural anesthesia is a common technique for perioperative analgesia and chronic pain treatment. Since ultrasonography is insufficient for depicting the human vertebral surface, most examiners apply epidural puncture by body surface landmarks on the back such as the spinous process and scapulae without any imaging, including ultrasonography. The puncture route to the epidural space at thoracic vertebrae is much narrower than that at lumber vertebrae, and therefore, epidural anesthesia at thoracic vertebrae is difficult, especially for a beginner. Herein, a novel imaging method is proposed based on a bi-static imaging technique by making use of the transmit beam width and direction. In an in vivo experimental study on human thoracic vertebrae, the proposed method succeeded in depicting the vertebral surface clearly as compared with conventional B-mode imaging and the conventional envelope method. This indicates the potential of the proposed method in visualizing the vertebral surface for the proper and safe execution of epidural anesthesia.

  11. Uncertainty analysis of point-by-point sampling complex surfaces using touch probe CMMs DOE for complex surfaces verification with CMM

    DEFF Research Database (Denmark)

    Barini, Emanuele Modesto; Tosello, Guido; De Chiffre, Leonardo

    2010-01-01

    The paper describes a study concerning point-by-point sampling of complex surfaces using tactile CMMs. A four factor, two level completely randomized factorial experiment was carried out, involving measurements on a complex surface configuration item comprising a sphere, a cylinder and a cone, co...

  12. Minimization of spurious strains by using a Si bent-perfect-crystal monochromator: neutron surface strain scanning of a shot-peened sample

    Science.gov (United States)

    Rebelo Kornmeier, Joana; Gibmeier, Jens; Hofmann, Michael

    2011-06-01

    Neutron strain measurements are critical at the surface. When scanning close to a sample surface, aberration peak shifts arise due to geometrical and divergence effects. These aberration peak shifts can be of the same order as the peak shifts related to residual strains. In this study it will be demonstrated that by optimizing the horizontal bending radius of a Si (4 0 0) monochromator, the aberration peak shifts from surface effects can be strongly reduced. A stress-free sample of fine-grained construction steel, S690QL, was used to find the optimal instrumental conditions to minimize aberration peak shifts. The optimized Si (4 0 0) monochromator and instrument settings were then applied to measure the residual stress depth gradient of a shot-peened SAE 4140 steel sample to validate the effectiveness of the approach. The residual stress depth profile is in good agreement with results obtained by x-ray diffraction measurements from an international round robin test (BRITE-EURAM-project ENSPED). The results open very promising possibilities to bridge the gap between x-ray diffraction and conventional neutron diffraction for non-destructive residual stress analysis close to surfaces.

  13. Minimization of spurious strains by using a Si bent-perfect-crystal monochromator: neutron surface strain scanning of a shot-peened sample

    International Nuclear Information System (INIS)

    Rebelo Kornmeier, Joana; Hofmann, Michael; Gibmeier, Jens

    2011-01-01

    Neutron strain measurements are critical at the surface. When scanning close to a sample surface, aberration peak shifts arise due to geometrical and divergence effects. These aberration peak shifts can be of the same order as the peak shifts related to residual strains. In this study it will be demonstrated that by optimizing the horizontal bending radius of a Si (4 0 0) monochromator, the aberration peak shifts from surface effects can be strongly reduced. A stress-free sample of fine-grained construction steel, S690QL, was used to find the optimal instrumental conditions to minimize aberration peak shifts. The optimized Si (4 0 0) monochromator and instrument settings were then applied to measure the residual stress depth gradient of a shot-peened SAE 4140 steel sample to validate the effectiveness of the approach. The residual stress depth profile is in good agreement with results obtained by x-ray diffraction measurements from an international round robin test (BRITE-EURAM-project ENSPED). The results open very promising possibilities to bridge the gap between x-ray diffraction and conventional neutron diffraction for non-destructive residual stress analysis close to surfaces

  14. Nonlinear optical probe of biopolymer adsorption on colloidal particle surface: poly-L-lysine on polystyrene sulfate microspheres.

    Science.gov (United States)

    Eckenrode, Heather M; Dai, Hai-Lung

    2004-10-12

    A nonlinear optical technique--second harmonic generation (SHG)--has been applied to characterize the adsorption of poly-L-lysine on micrometer size polystyrene particles, whose surface is covered with negatively charged sulfonate groups, in aqueous solutions. Adsorption behavior of the biopolymer with two chain lengths (14 and 75 amino acid units; PL14 and PL75) has been examined. Centrifugation experiments were also performed to support the adsorption measurements made using SHG. The adsorption free energies of the two polymers PL75 and PL14 are determined as -16.57 and -14.40 kcal/mol, respectively. The small difference in the adsorption free energies of the two chain lengths, however, leads to dramatic difference in the concentration needed for saturated surface coverage: nearly 50 times higher concentration is needed for the smaller polymer. Under acidic colloidal conditions, polylysine is found to adsorb in a relatively flat conformation on the surface. The surface area that each polylysine molecule occupies is nearly 1 order of magnitude larger than the size of the molecule in its extended form. The low adsorption density is likely a result from Coulombic repulsion between the positive charges on the amino acid units of PL. The measurements demonstrate the utility of SHG as an efficient and sensitive experimental approach for measuring adsorption characteristics of bio/macromolecules on colloidal particles and define surface and colloidal conditions for achieving maximum surface coverage of a widely used biopolymer. Copyright 2004 American Chemical Society

  15. ;Study of secondary hydriding at high temperature in zirconium based nuclear fuel cladding tubes by coupling information from neutron radiography/tomography, electron probe micro analysis, micro elastic recoil detection analysis and laser induced breakdown spectroscopy microprobe

    Science.gov (United States)

    Brachet, Jean-Christophe; Hamon, Didier; Le Saux, Matthieu; Vandenberghe, Valérie; Toffolon-Masclet, Caroline; Rouesne, Elodie; Urvoy, Stéphane; Béchade, Jean-Luc; Raepsaet, Caroline; Lacour, Jean-Luc; Bayon, Guy; Ott, Frédéric

    2017-05-01

    This paper gives an overview of a multi-scale experimental study of the secondary hydriding phenomena that can occur in nuclear fuel cladding materials exposed to steam at high temperature (HT) after having burst (loss-of-coolant accident conditions). By coupling information from several facilities, including neutron radiography/tomography, electron probe micro analysis, micro elastic recoil detection analysis and micro laser induced breakdown spectroscopy, it was possible to map quantitatively, at different scales, the distribution of oxygen and hydrogen within M5™ clad segments having experienced ballooning and burst at HT followed by steam oxidation at 1100 and 1200 °C and final direct water quenching down to room temperature. The results were very reproducible and it was confirmed that internal oxidation and secondary hydriding at HT of a cladding after burst can lead to strong axial and azimuthal gradients of hydrogen and oxygen concentrations, reaching 3000-4000 wt ppm and 1.0-1.2 wt% respectively within the β phase layer for the investigated conditions. Consistent with thermodynamic and kinetics considerations, oxygen diffusion into the prior-β layer was enhanced in the regions highly enriched in hydrogen, where the α(O) phase layer is thinner and the prior-β layer thicker. Finally the induced post-quenching hardening of the prior-β layer was mainly related to the local oxygen enrichment. Hardening directly induced by hydrogen was much less significant.

  16. Probing the Surface Charge on the Basal Planes of Kaolinite Particles with High-Resolution Atomic Force Microscopy.

    Science.gov (United States)

    Kumar, N; Andersson, M P; van den Ende, D; Mugele, F; Siretanu, I

    2017-12-19

    High-resolution atomic force microscopy is used to map the surface charge on the basal planes of kaolinite nanoparticles in an ambient solution of variable pH and NaCl or CaCl 2 concentration. Using DLVO theory with charge regulation, we determine from the measured force-distance curves the surface charge distribution on both the silica-like and the gibbsite-like basal plane of the kaolinite particles. We observe that both basal planes do carry charge that varies with pH and salt concentration. The silica facet was found to be negatively charged at pH 4 and above, whereas the gibbsite facet is positively charged at pH below 7 and negatively charged at pH above 7. Investigations in CaCl 2 at pH 6 show that the surface charge on the gibbsite facet increases for concentration up to 10 mM CaCl 2 and starts to decrease upon further increasing the salt concentration to 50 mM. The increase of surface charge at low concentration is explained by Ca 2+ ion adsorption, while Cl - adsorption at higher CaCl 2 concentrations partially neutralizes the surface charge. Atomic resolution imaging and density functional theory calculations corroborate these observations. They show that hydrated Ca 2+ ions can spontaneously adsorb on the gibbsite facet of the kaolinite particle and form ordered surface structures, while at higher concentrations Cl - ions will co-adsorb, thereby changing the observed ordered surface structure.

  17. Technological advances in cosmogenic neutron detectors for measuring soil water content

    Science.gov (United States)

    Zreda, M. G.; Schrön, M.; Köhli, M.

    2017-12-01

    The cosmic-ray neutron probe is used for measuring area-average soil water content at the hectometer scale. Early work showed a simple exponential decrease with distance of the instrument's sensitivity and a footprint 300 m in radius. Recent research suggested a much higher sensitivity to local neutrons and reduced footprint. We show results confirming the high sensitivity to local neutrons, describe two ways to reduce local and increase far-field effects, and propose ways of measuring neutrons at different spatial scales. Measurements with moderated detectors across a 10-m-wide creek and a 2-m-wide water tank show a decrease by 30% and 20%, respectively, of neutron intensity over water compared to that over land nearby. These results mean that the detector is sensitive to meter-scale heterogeneities of water content. This sensitivity can be reduced by rising the detector or by shielding it from local neutrons. The effect of local water distributions on the measured neutron intensity decreases with height. In the water tank experiment it disappeared almost completely at the height of 2 m, leading to the conjecture that the height roughly equal to the horizontal scale of heterogeneity would eliminate the sensitivity. This may or may not be practical. Shielding the detector below by a hydrogenous material removes a substantial fraction of the local neutrons. The shielded detector has a reduced count rate, reduced sensitivity to local neutrons and increased sensitivity to neutrons farther afield, and a larger footprint. Such a detector could be preferable to the current cosmogenic-neutron probe under heterogeneous soil water conditions. The shielding experiments also inspired the development of a local-area neutron detector. It has hydrogenous neutron shields on all sides except the bottom, substantially blocking the neutrons coming from afar, while allowing the neutrons coming directly from below. Its footprint is equal to its physical dimension when the detector is

  18. Contamination-free sounding rocket Langmuir probe

    Science.gov (United States)

    Amatucci, W. E.; Schuck, P. W.; Walker, D. N.; Kintner, P. M.; Powell, S.; Holback, B.; Leonhardt, D.

    2001-04-01

    A technique for removing surface contaminants from a sounding rocket spherical Langmuir probe is presented. Contamination layers present on probe surfaces can skew the collected data, resulting in the incorrect determination of plasma parameters. Despite following the usual probe cleaning techniques that are used prior to a launch, the probe surface can become coated with layers of adsorbed neutral gas in less than a second when exposed to atmosphere. The laboratory tests reported here show that by heating the probe from the interior using a small halogen lamp, adsorbed neutral particles can be removed from the probe surface, allowing accurate plasma parameter measurements to be made.

  19. Residual stress measurements by means of neutron diffraction

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  20. Commercial applications of neutron scattering

    International Nuclear Information System (INIS)

    Hutchings, M.T.

    1993-01-01

    The fact that industry is now willing to pay the full commercial cost for certain neutron scattering experiments aimed at solving its urgent materials - related problems is a true testimony to the usefulness of neutrons as microscopic probes. This paper gives examples of such use of three techniques drawn mainly from our experience at AEA Technology Harwell Laboratory. These are diffraction to measure residual stress, small angle neutron scattering to examine hardening precipitates in ferritic steels brought about by irradiation, and reflectivity to study amorphous diamond layers deposited on silicon. In most cases it is the penetrative power of the neutron which proves to be its best asset for commercial industrial applicaitons. (author)