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Sample records for nuclear field effect

  1. Effective field theory in nuclear physics

    SciTech Connect

    Martin J. Savage

    2000-12-12

    I review recent developments in the application of effective field theory to nuclear physics. Emphasis is placed on precision two-body calculations and efforts to formulate the nuclear shell model in terms of an effective field theory.

  2. Effective Field Theory in Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Chen, Jiunn-Wei

    2001-04-01

    I will discuss some basic ideas of effective field theory and its application to two nucleon systems. The theory allows a perturbative treatment of strongly interacting, bound state problems such that the calculations can be systematically improved and reliable error estimation performed. Also, the field theory formalism naturally allows manifest incorporation of symmetry properties such as gauge symmetry and Lorentz symmetry. Emphasis will be placed on some high precision calculations to low energy astrophysical problems: neutron radiative capture onto proton which is relevant to big-bang nucleosynthesis; neutrino deuteron inelastic scattering employed in the solar neutrino detection by Sudbury Neutrino Observatory (SNO) and the proton-proton solar fusion process which is an important process to fuel the sun. The last two classes of processes share the same two-body operator which is proposed to be measured at ORLAND and could serve to calibrate SNO and the solar fusion rate.

  3. Power counting and Wilsonian renormalization in nuclear effective field theory

    NASA Astrophysics Data System (ADS)

    Valderrama, Manuel Pavón

    2016-05-01

    Effective field theories are the most general tool for the description of low energy phenomena. They are universal and systematic: they can be formulated for any low energy systems we can think of and offer a clear guide on how to calculate predictions with reliable error estimates, a feature that is called power counting. These properties can be easily understood in Wilsonian renormalization, in which effective field theories are the low energy renormalization group evolution of a more fundamental — perhaps unknown or unsolvable — high energy theory. In nuclear physics they provide the possibility of a theoretically sound derivation of nuclear forces without having to solve quantum chromodynamics explicitly. However there is the problem of how to organize calculations within nuclear effective field theory: the traditional knowledge about power counting is perturbative but nuclear physics is not. Yet power counting can be derived in Wilsonian renormalization and there is already a fairly good understanding of how to apply these ideas to non-perturbative phenomena and in particular to nuclear physics. Here we review a few of these ideas, explain power counting in two-nucleon scattering and reactions with external probes and hint at how to extend the present analysis beyond the two-body problem.

  4. Regularization methods for Nuclear Lattice Effective Field Theory

    NASA Astrophysics Data System (ADS)

    Klein, Nico; Lee, Dean; Liu, Weitao; Meißner, Ulf-G.

    2015-07-01

    We investigate Nuclear Lattice Effective Field Theory for the two-body system for several lattice spacings at lowest order in the pionless as well as in the pionful theory. We discuss issues of regularizations and predictions for the effective range expansion. In the pionless case, a simple Gaussian smearing allows to demonstrate lattice spacing independence over a wide range of lattice spacings. We show that regularization methods known from the continuum formulation are necessary as well as feasible for the pionful approach.

  5. Nuclear Parity-Violation in Effective Field Theory

    SciTech Connect

    Shi-Lin Zhu; C.M. Maekawa; B.R. Holstein; M.J. Ramsey-Musolf; U van Kolck

    2005-02-21

    We reformulate the analysis of nuclear parity-violation (PV) within the framework of effective field theory (EFT). To order Q, the PV nucleon-nucleon (NN) interaction depends on five a priori unknown constants that parameterize the leading-order, short-range four-nucleon operators. When pions are included as explicit degrees of freedom, the potential contains additional medium- and long-range components parameterized by PV piNN couplings. We derive the form of the corresponding one- and two-pion-exchange potentials. We apply these considerations to a set of existing and prospective PV few-body measurements that may be used to determine the five independent low-energy constants relevant to the pionless EFT and the additional constants associated with dynamical pions. We also discuss the relationship between the conventional meson-exchange framework and the EFT formulation, and argue that the latter provides a more general and systematic basis for analyzing nuclear PV.

  6. Effective field theory for nuclear vibrations with quantified uncertainties

    NASA Astrophysics Data System (ADS)

    Coello Pérez, E. A.; Papenbrock, T.

    2015-12-01

    We develop an effective field theory (EFT) for nuclear vibrations. The key ingredients—quadrupole degrees of freedom, rotational invariance, and a breakdown scale around the three-phonon level—are taken from data. The EFT is developed for spectra and electromagnetic moments and transitions. We employ tools from Bayesian statistics for the quantification of theoretical uncertainties. The EFT consistently describes spectra and electromagnetic transitions for 62Ni,100,98Ru,108,106Pd, 110,112,114Cd, and 118,120,122Te within the theoretical uncertainties. This suggests that these nuclei can be viewed as anharmonic vibrators.

  7. Three-Body Nuclear Systems in Pionless Effective Field Theory

    NASA Astrophysics Data System (ADS)

    Vanasse, Jared

    2016-03-01

    New perturbative techniques for three-body systems with contact interactions are discussed. Their application to pionless effective field theory (EF{Tnot π }) for nd scattering is shown, and their extension to bound states addressed. With the extension to bound states a leading-order EF{Tnot π } calculation of the triton charge radius and novel treatments of three-body forces are discussed.

  8. Nuclear axial currents in chiral effective field theory

    DOE PAGESBeta

    Baroni, Alessandro; Girlanda, Luca; Pastore, Saori; Schiavilla, Rocco; Viviani, Michele

    2016-01-11

    Two-nucleon axial charge and current operators are derived in chiral effective field theory up to one loop. The derivation is based on time-ordered perturbation theory and accounts for cancellations between the contributions of irreducible diagrams and the contributions owing to nonstatic corrections from energy denominators of reducible diagrams. Ultraviolet divergencies associated with the loop corrections are isolated in dimensional regularization. The resulting axial current is finite and conserved in the chiral limit, while the axial charge requires renormalization. As a result, a complete set of contact terms for the axial charge up to the relevant order in the power countingmore » is constructed.« less

  9. Power counting for nuclear forces in chiral effective field theory

    NASA Astrophysics Data System (ADS)

    Long, Bingwei

    2016-02-01

    The present note summarizes the discourse on power counting issues of chiral nuclear forces, with an emphasis on renormalization-group invariance. Given its introductory nature, I will lean toward narrating a coherent point of view on the concepts, rather than covering comprehensively the development of chiral nuclear forces in different approaches.

  10. Ab initio nuclear structure from lattice effective field theory

    SciTech Connect

    Lee, Dean

    2014-11-11

    This proceedings article reviews recent results by the Nuclear Lattice EFT Collaboration on an excited state of the {sup 12}C nucleus known as the Hoyle state. The Hoyle state plays a key role in the production of carbon via the triple-alpha reaction in red giant stars. We discuss the structure of low-lying states of {sup 12}C as well as the dependence of the triple-alpha reaction on the masses of the light quarks.

  11. Influence of nuclear spin on chemical reactions: Magnetic isotope and magnetic field effects (A Review)

    PubMed Central

    Turro, Nicholas J.

    1983-01-01

    The course of chemical reactions involving radical pairs may depend on occurrence and orientation of nuclear spins in the pairs. The influence of nuclear spins is maximized when the radical pairs are confined to a space that serves as a cage that allows a certain degree of independent diffusional and rotational motion of the partners of the pair but that also encourages reencounters of the partners within a period which allows the nuclear spins to operate on the odd electron spins of the pair. Under the proper conditions, the nuclear spins can induce intersystem crossing between triplet and singlet states of radical pairs. It is shown that this dependence of intersystem crossing on nuclear spin leads to a magnetic isotope effect on the chemistry of radical pairs which provides a means of separating isotopes on the basis of nuclear spins rather than nuclear masses and also leads to a magnetic field effect on the chemistry of radical pairs which provides a means of influencing the course of polymerization by the application of weak magnetic fields. PMID:16593273

  12. Spinodal instabilities and the distillation effect in nuclear matter under strong magnetic fields

    SciTech Connect

    Rabhi, A.; Providencia, C.; Providencia, J. Da

    2009-01-15

    We study the effect of strong magnetic fields, of the order of 10{sup 18}-10{sup 19} G, on the instability region of nuclear matter at subsaturation densities. Relativistic nuclear models both with constant couplings and with density-dependent parameters are considered. It is shown that a strong magnetic field can have large effects on the instability regions giving rise to bands of instability and wider unstable regions. As a consequence, we predict larger transition densities at the inner edge of the crust of compact stars with strong magnetic fields. The direction of instability gives rise to a very strong distillation effect if the last Landau level is only partially filled. However, for almost completed Landau levels, an antidistillation effect may occur.

  13. What Do Effective Field Theories Tell Us About the Nuclear Force?

    NASA Astrophysics Data System (ADS)

    Friar, J. L.

    2003-10-01

    Potentials are the tools that traditional nuclear physics uses to calculate bound states and reaction rates. First-generation potentials (developed more than a decade ago) used many different mechanisms to motivate shapes and strengths, while their fits to nucleon-nucleon scattering data were indifferent. Second-generation potentials, whose fits to data range from good to excellent, were constructed within the past decade using the same motivations. Accurate third-generation potentials are now being developed using the language and techniques of chiral perturbation theory, which is an effective field theory based on the symmetries of QCD. The philosophy of such effective field theories has made a large impact on the way I view nuclear potentials. Power counting, for example, uses the scales of strongly interacting systems to provide a systematic and concise organizational scheme that subsumes both two-nucleon and three-nucleon potentials. Although this new development has led to a rapid advance in our understanding of nuclear forces (especially in isospin violation), much of this work mirrors traditional approaches. Many of the techniques usually associated with field theory (such as regularization and renormalization, for example) also have direct analogues in more traditional approaches to constructing potentials. Examples of nuclear-force mechanisms and their associated scales will be discussed throughout the talk, together with my appreciation of how well we understand the nuclear force.

  14. Chiral symmetry and effective field theories for hadronic, nuclear and stellar matter

    NASA Astrophysics Data System (ADS)

    Holt, Jeremy W.; Rho, Mannque; Weise, Wolfram

    2016-03-01

    Chiral symmetry, first entering in nuclear physics in the 1970s for which Gerry Brown played a seminal role, has led to a stunningly successful framework for describing strongly-correlated nuclear dynamics both in finite and infinite systems. We review how the early, germinal idea conceived with the soft-pion theorems in the pre-QCD era has evolved into a highly predictive theoretical framework for nuclear physics, aptly assessed by Steven Weinberg: "it (chiral effective field theory) allows one to show in a fairly convincing way that what they (nuclear physicists) have been doing all along... is the correct first step in a consistent approximation scheme". Our review recounts both how the theory presently fares in confronting Nature and how one can understand its extremely intricate workings in terms of the multifaceted aspects of chiral symmetry, namely, chiral perturbation theory, skyrmions, Landau Fermi-liquid theory, the Cheshire cat phenomenon, and hidden local and mended symmetries.

  15. Dissertation in Nuclear Physics Award Talk: Effective Field Theory for Nuclear Physics

    NASA Astrophysics Data System (ADS)

    Chen, Jiunn-Wei

    2002-04-01

    I will discuss some basic ideas of effective field theory and its application to two nucleon systems. The theory allows a perturbative treatment of strongly interacting, bound state problems such that the calculations can be systematically improved and reliable error estimation performed. Also, the field theory formalism naturally allows manifest incorporation of symmetry properties such as gauge symmetry and Lorentz symmetry. Emphasis will be placed on some high precision calculations to low energy astrophysical problems: neutron radiative capture onto proton which is relevant to big-bang nucleosynthesis; neutrino deuteron inelastic scattering employed in the solar neutrino detection by Sudbury Neutrino Observatory (SNO) and the proton-proton solar fusion process which is an important process to fuel the sun. The last two classes of processes share the same two-body operator which is proposed to be measured at ORLAND and could serve to calibrate SNO and the solar fusion rate.

  16. Effect of the {delta} meson on the instabilities of nuclear matter under strong magnetic fields

    SciTech Connect

    Rabhi, A.; Providencia, C.; Da Providencia, J.

    2009-08-15

    We study the influence of the isovector-scalar meson on the spinodal instabilities and the distillation effect in asymmetric nonhomogenous nuclear matter under strong magnetic fields of the order of 10{sup 18}-10{sup 19} G. Relativistic nuclear models both with constant couplings (NLW) and with density-dependent parameters (DDRH) are considered. A strong magnetic field can have large effects on the instability regions giving rise to bands of instability and wider unstable regions. It is shown that for neutron-rich matter the inclusion of the {delta} meson increases the size of the instability region for NLW models and decreases it for the DDRH models. The effect of the {delta} meson on the transition density to homogeneous {beta}-equilibrium matter is discussed. The DDRH{delta} model predicts the smallest transition pressures, about half the values obtained for NL{delta}.

  17. The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

    SciTech Connect

    Mance, Deni; Baldus, Marc; Gast, Peter; Huber, Martina; Ivanov, Konstantin L.

    2015-06-21

    We develop a theoretical description of Dynamic Nuclear Polarization (DNP) in solids under Magic Angle Spinning (MAS) to describe the magnetic field dependence of the DNP effect. The treatment is based on an efficient scheme for numerical solution of the Liouville-von Neumann equation, which explicitly takes into account the variation of magnetic interactions during the sample spinning. The dependence of the cross-effect MAS-DNP on various parameters, such as the hyperfine interaction, electron-electron dipolar interaction, microwave field strength, and electron spin relaxation rates, is analyzed. Electron spin relaxation rates are determined by electron paramagnetic resonance measurements, and calculations are compared to experimental data. Our results suggest that the observed nuclear magnetic resonance signal enhancements provided by MAS-DNP can be explained by discriminating between “bulk” and “core” nuclei and by taking into account the slow DNP build-up rate for the bulk nuclei.

  18. The magnetic field dependence of cross-effect dynamic nuclear polarization under magic angle spinning

    NASA Astrophysics Data System (ADS)

    Mance, Deni; Gast, Peter; Huber, Martina; Baldus, Marc; Ivanov, Konstantin L.

    2015-06-01

    We develop a theoretical description of Dynamic Nuclear Polarization (DNP) in solids under Magic Angle Spinning (MAS) to describe the magnetic field dependence of the DNP effect. The treatment is based on an efficient scheme for numerical solution of the Liouville-von Neumann equation, which explicitly takes into account the variation of magnetic interactions during the sample spinning. The dependence of the cross-effect MAS-DNP on various parameters, such as the hyperfine interaction, electron-electron dipolar interaction, microwave field strength, and electron spin relaxation rates, is analyzed. Electron spin relaxation rates are determined by electron paramagnetic resonance measurements, and calculations are compared to experimental data. Our results suggest that the observed nuclear magnetic resonance signal enhancements provided by MAS-DNP can be explained by discriminating between "bulk" and "core" nuclei and by taking into account the slow DNP build-up rate for the bulk nuclei.

  19. Nuclear-spin-induced cotton-mouton effect in a strong external magnetic field.

    PubMed

    Fu, Li-Juan; Vaara, Juha

    2014-08-01

    Novel, high-sensitivity and high-resolution spectroscopic methods can provide site-specific nuclear information by exploiting nuclear magneto-optic properties. We present a first-principles electronic structure formulation of the recently proposed nuclear-spin-induced Cotton-Mouton effect in a strong external magnetic field (NSCM-B). In NSCM-B, ellipticity is induced in a linearly polarized light beam, which can be attributed to both the dependence of the symmetric dynamic polarizability on the external magnetic field and the nuclear magnetic moment, as well as the temperature-dependent partial alignment of the molecules due to the magnetic fields. Quantum-chemical calculations of NSCM-B were conducted for a series of molecular liquids. The overall order of magnitude of the induced ellipticities is predicted to be 10(-11) -10(-6) rad T(-1)  M(-1)  cm(-1) for fully spin-polarized nuclei. In particular, liquid-state heavy-atom systems should be promising for experiments in the Voigt setup. PMID:24862946

  20. Effective meson masses in nuclear matter based on a cutoff field theory

    SciTech Connect

    Nakano, M.; Noda, N.; Mitsumori, T.; Koide, K.; Kouno, H.; Hasegawa, A.

    1997-02-01

    Effective masses of {sigma}, {omega}, {pi}, and {rho} mesons in nuclear matter are calculated based on a cutoff field theory. Instead of the traditional density-Feynman representation, we adopt the particle-hole-antiparticle representation for nuclear propagators so that unphysical components are not included in the meson self-energies. For an estimation of the contribution from the divergent particle-antiparticle excitations, i.e., vacuum polarization in nuclear matter, the idea of the renormalization group method is adopted. In this cutoff field theory, all the counterterms are finite and calculated numerically. It is shown that the predicted meson masses converge even if the cutoff {Lambda} is changed as long as {Lambda} is sufficiently large and that the prescription works well also for so-called nonrenormalized mesons such as {pi} and {rho}. According to this method, it is concluded that meson masses in nuclear matter have a weak dependence on the baryon density. {copyright} {ital 1997} {ital The American Physical Society}

  1. Probing the effective nuclear-spin magnetic field in a single quantum dot via full counting statistics

    SciTech Connect

    Xue, Hai-Bin; Nie, Yi-Hang; Chen, Jingzhe; Ren, Wei

    2015-03-15

    We study theoretically the full counting statistics of electron transport through a quantum dot weakly coupled to two ferromagnetic leads, in which an effective nuclear-spin magnetic field originating from the configuration of nuclear spins is considered. We demonstrate that the quantum coherence between the two singly-occupied eigenstates and the spin polarization of two ferromagnetic leads play an important role in the formation of super-Poissonian noise. In particular, the orientation and magnitude of the effective field have a significant influence on the variations of the values of high-order cumulants, and the variations of the skewness and kurtosis values are more sensitive to the orientation and magnitude of the effective field than the shot noise. Thus, the high-order cumulants of transport current can be used to qualitatively extract information on the orientation and magnitude of the effective nuclear-spin magnetic field in a single quantum dot. - Highlights: • The effective nuclear-spin magnetic field gives rise to the off-diagonal elements of the reduced density matrix of single QD. • The off-diagonal elements of reduced density matrix of the QD have a significant impact on the high-order current cumulants. • The high-order current cumulants are sensitive to the orientation and magnitude of the effective nuclear-spin magnetic field. • The FCS can be used to detect the orientation and magnitude of the effective nuclear-spin magnetic field in a single QD.

  2. Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects

    SciTech Connect

    Urban, Jeffry Todd

    2004-12-21

    Experimental and theoretical research conducted in two areas in the field of nuclear magnetic resonance (NMR) spectroscopy is presented: (1) studies of the coherent quantum-mechanical control of the angular momentum dynamics of quadrupolar (spin I > 1/2) nuclei and its application to the determination of molecular structure; and (2) applications of the long-range nuclear dipolar field to novel NMR detection methodologies.The dissertation is organized into six chapters. The first two chapters and associated appendices are intended to be pedagogical and include an introduction to the quantum mechanical theory of pulsed NMR spectroscopy and the time dependent theory of quantum mechanics. The third chapter describes investigations of the solid-state multiple-quantum magic angle spinning (MQMAS) NMR experiment applied to I = 5/2 quadrupolar nuclei. This work reports the use of rotary resonance-matched radiofrequency irradiation for sensitivity enhancement of the I = 5/2 MQMAS experiment. These experiments exhibited certain selective line narrowing effects which were investigated theoretically.The fourth chapter extends the discussion of multiple quantum spectroscopy of quadrupolar nuclei to a mostly theoretical study of the feasibility of enhancing the resolution of nitrogen-14 NMR of large biomolecules in solution via double-quantum spectroscopy. The fifth chapter continues to extend the principles of multiple quantum NMR spectroscopy of quadrupolar nuclei to make analogies between experiments in NMR/nuclear quadrupolar resonance (NQR) and experiments in atomic/molecular optics (AMO). These analogies are made through the Hamiltonian and density operator formalism of angular momentum dynamics in the presence of electric and magnetic fields.The sixth chapter investigates the use of the macroscopic nuclear dipolar field to encode the NMR spectrum of an analyte nucleus indirectly in the magnetization of a sensor nucleus. This technique could potentially serve as an

  3. Effect of the Nuclear Hyperfine Field on the 2D Electron Conductivity in the Quantum Hall Regime

    SciTech Connect

    VITKALOV,S.A.; BOWERS,C.R.; SIMMONS,JERRY A.; RENO,JOHN L.

    2000-07-13

    The effect of the nuclear hyperfine interaction on the dc conductivity of 2D electrons under quantum Hall effect conditions at filling factor v= 1 is observed for the first time. The local hyperfine field enhanced by dynamic nuclear polarization is monitored via the Overhauser shift of the 2D conduction electron spin resonance in AlGaAs/GaAs multiquantum-well samples. The experimentally observed change in the dc conductivity resulting from dynamic nuclear polarization is in agreement with a thermal activation model incorporating the Zeeman energy change due to the hyperfine interaction. The relaxation decay time of the dc conductivity is, within experimental error, the same as the relaxation time of the nuclear spin polarization determined from the Overhauser shift. These findings unequivocally establish the nuclear spin origins of the observed conductivity change.

  4. Optimal Dense Coding and Swap Operation Between Two Coupled Electronic Spins: Effects of Nuclear Field and Spin-Orbit Interaction

    NASA Astrophysics Data System (ADS)

    Jiang, Li; Zhang, Guo-Feng

    2016-08-01

    The effects of nuclear field and spin-orbit interaction on dense coding and swap operation are studied in detail for both the antiferromagnetic (AFM) and ferromagnetic (FM) coupling cases. The conditions for a valid dense coding and under which swap operation is feasible are given.

  5. Correlation between effective and ambient neutron doses in radiation fields of nuclear-physics facilities at the joint institute for nuclear research

    NASA Astrophysics Data System (ADS)

    Guseva, S. V.; Lesovaya, E. N.; Timoshenko, G. N.

    2015-01-01

    The questions of a correlation between normative and operational quantities in the dosimetry of ionizing radiation still attract the attention of professionals working in the field. Since the neutron fields of nuclear-physics facilities at the Joint Institute for Nuclear Research (JINR) are highly varied, the question of whether the ambient neutron dose always serves as a conservative estimate of the effective dose (in the terms of which the dose limits are set) is of practical importance for radiation monitoring at JINR. We studied the correlation between the calculated values of effective and ambient neutron doses obtained based on a representative set of neutron spectra measured at JINR with the use of a multisphere neutron spectrometer. It is demonstrated that measuring the ambient neutron dose may not serve as a confirmation of compliance with the set dose limits in "hard" neutron fields.

  6. A review on the relativistic effective field theory with parameterized couplings for nuclear matter and neutron stars

    NASA Astrophysics Data System (ADS)

    Vasconcellos, C. A. Zen

    2015-12-01

    Nuclear science has developed many excellent theoretical models for many-body systems in the domain of the baryon-meson strong interaction for the nucleus and nuclear matter at low, medium and high densities. However, a full microscopic understanding of nuclear systems in the extreme density domain of compact stars is still lacking. The aim of this contribution is to shed some light on open questions facing the nuclear many-body problem at the very high density domain. Here we focus our attention on the conceptual issue of naturalness and its role in shaping the baryon-meson phase space dynamics in the description of the equation of state (EoS) of nuclear matter and neutrons stars. In particular, in order to stimulate possible new directions of research, we discuss relevant aspects of a recently developed relativistic effective theory for nuclear matter within Quantum Hadrodynamics (QHD) with genuine many-body forces and derivative natural parametric couplings. Among other topics we discuss in this work the connection of this theory with other known effective QHD models of the literature and its potentiality in describing a new physics for dense matter. The model with parameterized couplings exhausts the whole fundamental baryon octet (n, p, Σ-, Σ0, Σ+, Λ, Ξ-, Ξ0) and simulates n-order corrections to the minimal Yukawa baryon couplings by considering nonlinear self-couplings of meson fields and meson-meson interaction terms coupled to the baryon fields involving scalar-isoscalar (σ, σ∗), vector-isoscalar (ω, ɸ), vector-isovector (ϱ) and scalar-isovector (δ) virtual sectors. Following recent experimental results, we consider in our calculations the extreme case where the Σ- experiences such a strong repulsion that its influence in the nuclear structure of a neutron star is excluded at all. A few examples of calculations of properties of neutron stars are shown and prospects for the future are discussed.

  7. Effects of magnetic fields on the nuclear burning propagation and the Type Ia SNe runaway

    NASA Astrophysics Data System (ADS)

    Hristov, Boyan; Collins, David C.; Hoeflich, Peter; Weatherford, Charles

    2016-01-01

    The consistency of Type Ia SNe allows for simple descriptions of the phenomena founded on basic physics and yet no theory is able to explain the observations entirely. In particular we are addressing an outstanding problem with current 3D simulations, in which Rayleigh-Taylor (RT) instabilities bring too much burned material to the outer layers thus mixing iron group elements towards the surface but those are not observed. Additionally light curves are reproduced well only in spherically symmetric explosions, while they break down when instabilities are present. We attempt to explain these discrepancies by introducing magnetic fields, which affects the rate of growth of unstable modes. Specifically it increases the growth rate of modes parallel to itself and suppress the transverse modes. This reduces the mixing in two possible ways: stronger burning causes faster pre-expansion, then plumes rise with the similar speed as the surrounding material is expanding; and RT instabilities are suppressed so much that they don't rise at all. Our preliminary models run in a rectangular domain inside a C/O white dwarf (WD) extending 120km along the stellar radius and is about 15km on the side. External magnetic fields between 1e4G and 1e9G are superimposed at various angles to the WD radius. A simple two-species nuclear network is employed in the form of fuel-product (C/O -> 56Ni). The front propagation is modeled as diffusion of the burned fraction of the C/O fuel. All simulations were done with Enzo - a 3D AMR MHD code for astrophysical and cosmological imulations, which was enhanced with additional physics for the nuclear burning. Future work will extend to full star simulations and more complex nuclear networks.

  8. Magnetic field effect on charmonium formation in high energy nuclear collisions

    NASA Astrophysics Data System (ADS)

    Guo, Xingyu; Shi, Shuzhe; Xu, Nu; Xu, Zhe; Zhuang, Pengfei

    2015-12-01

    It is important to understand the strong external magnetic field generated at the very beginning of heavy ion collisions. We study the effect of the magnetic field on the anisotropic charmonium formation in Pb + Pb collisions at the LHC energy. The time dependent Schrödinger equation is employed to describe the motion of c c bar pairs. We compare our model prediction of the non-collective anisotropic parameter v2 of J / ψ with CMS data at high transverse momentum.

  9. Some nuclear magnetic resonance studies of the effect of electric field on lipid dispersions

    NASA Astrophysics Data System (ADS)

    Osman, Peter Damien

    1997-11-01

    A method has been developed for studying, by NMR spectroscopy, the effect of pulsed electric fields on lipid aggregate structures such as bilayers and inverted hexagonal tubules as well as on the lipid conformation. Sample conductivity and ohmic heating caused the lipid to dehydrate under some test conditions and led to the use of glycerol as a substitute for water in membrane dispersions. It was found possible to produce aligned lipid multilayers which appeared very similar in spectral character to those obtained using water and lipid. Such membranes were more stable and possessed low ionic conduction. Additionally, it was possible to use the temperature dependence of chemical shifts in the NMR spectra to measure the ohmic heating effects resulting from the application of electric field to a lipid multilayer stack. The effect of electric fields on several lipids were investigated, including: egg yolk phosphatidylcholine, dioleoylphosphatidylcholine, dioleoylphosphatidylethanolamine and dimyristoylphosphatidylcholine; together with mixtures of these lipids. Additionally lipids in which the voltage dependent ionophore alamethicin was included were tested. It was observed that electric fields below 16 MV/m had little direct effect on the conformation of lipid molecules, although slight changes were observed in the lipid headgroup region of lipid-glycerol multilayers. However, alterations in the long range order were observed including the rotation of lipid tubules in the inverted hexagonal phase; a lowering of the lamellar to inverted hexagonal phase transition temperature, and alteration of the spectra from aligned lipid multilayers of mixed lipids to spectra consistent with a viscous isotropic phase. Analyses were carried out to predict the effect of electric field on lipid dispersions. These included a model for the dielectrophoretic reorientation of elongated structures. This model was tested using dioleoylphosphatidylethanolamine in the inverted hexagonal phase

  10. A review on the relativistic effective field theory with parameterized couplings for nuclear matter and neutron stars

    SciTech Connect

    Vasconcellos, C. A. Zen

    2015-12-17

    Nuclear science has developed many excellent theoretical models for many-body systems in the domain of the baryon-meson strong interaction for the nucleus and nuclear matter at low, medium and high densities. However, a full microscopic understanding of nuclear systems in the extreme density domain of compact stars is still lacking. The aim of this contribution is to shed some light on open questions facing the nuclear many-body problem at the very high density domain. Here we focus our attention on the conceptual issue of naturalness and its role in shaping the baryon-meson phase space dynamics in the description of the equation of state (EoS) of nuclear matter and neutrons stars. In particular, in order to stimulate possible new directions of research, we discuss relevant aspects of a recently developed relativistic effective theory for nuclear matter within Quantum Hadrodynamics (QHD) with genuine many-body forces and derivative natural parametric couplings. Among other topics we discuss in this work the connection of this theory with other known effective QHD models of the literature and its potentiality in describing a new physics for dense matter. The model with parameterized couplings exhausts the whole fundamental baryon octet (n, p, Σ{sup −}, Σ{sup 0}, Σ{sup +}, Λ, Ξ{sup −}, Ξ{sup 0}) and simulates n-order corrections to the minimal Yukawa baryon couplings by considering nonlinear self-couplings of meson fields and meson-meson interaction terms coupled to the baryon fields involving scalar-isoscalar (σ, σ∗), vector-isoscalar (ω, Φ), vector-isovector (ϱ) and scalar-isovector (δ) virtual sectors. Following recent experimental results, we consider in our calculations the extreme case where the Σ{sup −} experiences such a strong repulsion that its influence in the nuclear structure of a neutron star is excluded at all. A few examples of calculations of properties of neutron stars are shown and prospects for the future are discussed.

  11. Views of a devil`s advocate -- Fundamental challenges to effective field theory treatments of nuclear physics

    SciTech Connect

    Cohen, T.D.

    1998-04-01

    The physics goals of the effective field theory program for nuclear phenomena are outlined. It is pointed out that there are multiple schemes for implementing EFT and it is presently not clear if any of these schemes is viable. Most of the applications of effective field theory ideas have been on nucleon-nucleon scattering. It is argued that this is little more than curve fitting and that other quantities need to be calculated to test the ideas. It is shown that EFT methods work well for certain bound state properties of the deuteron electric form factor. However, it is also shown that this success depends sensitively on the fact that the majority of the probability of the deuteron`s wave function is beyond the range of the potential. This circumstance is special to the deuteron suggesting that it will be very difficult to achieve the same kinds of success for tightly bound nuclei.

  12. Nuclear weapons, nuclear effects, nuclear war

    SciTech Connect

    Bing, G.F.

    1991-08-20

    This paper provides a brief and mostly non-technical description of the militarily important features of nuclear weapons, of the physical phenomena associated with individual explosions, and of the expected or possible results of the use of many weapons in a nuclear war. Most emphasis is on the effects of so-called ``strategic exchanges.``

  13. Nuclear magnetic resonance relaxation and diffusion in the presence of internal gradients: the effect of magnetic field strength.

    PubMed

    Mitchell, J; Chandrasekera, T C; Johns, M L; Gladden, L F; Fordham, E J

    2010-02-01

    It is known that internal magnetic field gradients in porous materials, caused by susceptibility differences at the solid-fluid interfaces, alter the observed effective Nuclear Magnetic Resonance transverse relaxation times T2,eff. The internal gradients scale with the strength of the static background magnetic field B0. Here, we acquire data at various magnitudes of B0 to observe the influence of internal gradients on T2-T2 exchange measurements; the theory discussed and observations made are applicable to any T2-T2 analysis of heterogeneous materials. At high magnetic field strengths, it is possible to observe diffusive exchange between regions of local internal gradient extrema within individual pores. Therefore, the observed exchange pathways are not associated with pore-to-pore exchange. Understanding the significance of internal gradients in transverse relaxation measurements is critical to interpreting these results. We present the example of water in porous sandstone rock and offer a guideline to determine whether an observed T2,eff relaxation time distribution reflects the pore size distribution for a given susceptibility contrast (magnetic field strength) and spin echo separation. More generally, we confirm that for porous materials T1 provides a better indication of the pore size distribution than T2,eff at high magnetic field strengths (B0>1 T), and demonstrate the data analysis necessary to validate pore size interpretations of T2,eff measurements. PMID:20365625

  14. In situ effective diffusion coefficient profiles in live biofilms using pulsed-field gradient nuclear magnetic resonance

    PubMed Central

    Renslow, Ryan S.; Majors, Paul D.; McLean, Jeffrey S.; Fredrickson, Jim K.; Ahmed, Bulbul; Beyenal, Haluk

    2010-01-01

    Diffusive mass transfer in biofilms is characterized by the effective diffusion coefficient. It is well-documented that the effective diffusion coefficient can vary by location in a biofilm. The current literature is dominated by effective diffusion coefficient measurements for distinct cell clusters and stratified biofilms showing this spatial variation. Regardless of whether distinct cell clusters or surface-averaging methods are used, position-dependent measurements of the effective diffusion coefficient are currently: 1) invasive to the biofilm, 2) performed under unnatural conditions, 3) lethal to cells, and/or 4) spatially restricted to only certain regions of the biofilm. Invasive measurements can lead to inaccurate results and prohibit further (time-dependent) measurements which are important for the mathematical modeling of biofilms. In this study our goals were to: 1) measure the effective diffusion coefficient for water in live biofilms, 2) monitor how the effective diffusion coefficient changes over time under growth conditions, and 3) correlate the effective diffusion coefficient with depth in the biofilm. We measured in situ two-dimensional effective diffusion coefficient maps within Shewanella oneidensis MR-1 biofilms using pulsed-field gradient nuclear magnetic resonance methods, and used them to calculate surface-averaged relative effective diffusion coefficient (Drs) profiles. We found that 1) Drs decreased from the top of the biofilm to the bottom, 2) Drs profiles differed for biofilms of different ages, 3) Drs profiles changed over time and generally decreased with time, 4) all the biofilms showed very similar Drs profiles near the top of the biofilm, and 5) the Drs profile near the bottom of the biofilm was different for each biofilm. Practically, our results demonstrate that advanced biofilm models should use a variable effective diffusivity which changes with time and location in the biofilm. PMID:20589671

  15. In Situ Effective Diffusion Coefficient Profiles in Live Biofilms Using Pulsed-Field Gradient Nuclear Magnetic Resonance

    SciTech Connect

    Renslow, Ryan S.; Majors, Paul D.; McLean, Jeffrey S.; Fredrickson, Jim K.; Ahmed, B.; Beyenal, Haluk

    2010-08-15

    Diffusive mass transfer in biofilms is characterized by the effective diffusion coefficient. It is well-documented that the effective diffusion coefficient can vary by location in a biofilm. The current literature is dominated by effective diffusion coefficient measurements for distinct cell clusters and stratified biofilms showing this spatial variation. Regardless of whether distinct cell clusters or surface-averaging methods are used, position-dependent measurements of the effective diffusion coefficient are currently: 1) invasive to the biofilm, 2) performed under unnatural conditions, 3) lethal to cells, and/or 4) spatially restricted to only certain regions of the biofilm. Invasive measurements can lead to inaccurate results and prohibit further (time dependent) measurements which are important for the mathematical modeling of biofilms. In this study our goals were to: 1) measure the effective diffusion coefficient for water in live biofilms, 2) monitor how the effective diffusion coefficient changes over time under growth conditions, and 3) correlate the effective diffusion coefficient with depth in the biofilm. We measured in situ two-dimensional effective diffusion coefficient maps within Shewanella oneidensis MR-1biofilms using pulsed-field gradient nuclear magnetic resonance methods, and used them to calculate surface-averaged relative effective diffusion coefficient (Drs) profiles. We found that 1) Drs decreased from the top of the biofilm to the bottom, 2) Drs profiles differed for biofilms of different ages, 3) Drs profiles changed over time and generally decreased with time, 4) all the biofilms showed very similar Drs profiles near the top of the biofilm, and 5) the Drs profile near the bottom of the biofilm was different for each biofilm. Practically, our results demonstrate that advanced biofilm models should use a variable effective diffusivity which changes with time and location in the biofilm.

  16. Radiation effects on materials in the near-field of a nuclear waste repository. 1997 annual progress report

    SciTech Connect

    Wang, L.M.; Ewing, R.C.

    1997-11-25

    'Sheet silicates (e.g. micas and clays) are important constituents of a wide variety of geological formations such as granite, basalt, and sandstone. Sheet silicates, particularly clays such as bentonite are common materials in near-field engineered barriers in high-level nuclear waste (HLW) repositories. This is because migration of radionuclides from an underground HLW repository to the geosphere may be significantly reduced by sorption of radionuclides (e.g., Pu, U and Np) onto sheet silicates (e.g., clays and micas) that line the fractures and pores of the rocks along groundwater flowpaths. In addition to surface sorption, it has been suggested that some sheet silicates may also be able to incorporate many radionuclides, such as Cs and Sr, in the inter-layer sites of the sheet structure. However, theability of the sheet silicates to incorporate radionuclides and retard release and migration of radionuclides may be significantly affected by the near-field radiation due to the decay of fission products and actinides. for example, the unique properties of the sheet structures will be lost completely if the structure becomes amorphous due to irradiation effects. Thus, the study of irradiation effects on sheet-structures, such as structural damage and modification of chemical properties, are critical to the performance assessment of long-term repository behavior.'

  17. RADIATION EFFECTS ON MATERIALS IN THE NEAR-FIELD OF NUCLEAR WASTE REPOSITORY

    EPA Science Inventory

    Successful, demonstrated containment of radionuclides in the near-field can greatly reduce the complexity of the performance assessment analysis of a geologic repository. The chemical durability of the waste form, the corrosion rate of the canister, and the physical and chemical ...

  18. Homogenized moment tensor and the effect of near-field heterogeneities on nonisotropic radiation in nuclear explosion

    NASA Astrophysics Data System (ADS)

    Burgos, Gaël.; Capdeville, Yann; Guillot, Laurent

    2016-06-01

    We investigate the effect of small-scale heterogeneities close to a seismic explosive source, at intermediate periods (20-50 s), with an emphasis on the resulting nonisotropic far-field radiation. First, using a direct numerical approach, we show that small-scale elastic heterogeneities located in the near-field of an explosive source, generate unexpected phases (i.e., long period S waves). We then demonstrate that the nonperiodic homogenization theory applied to 2-D and 3-D elastic models, with various pattern of small-scale heterogeneities near the source, leads to accurate waveforms at a reduced computational cost compared to direct modeling. Further, it gives an interpretation of how nearby small-scale features interact with the source at low frequencies, through an explicit correction to the seismic moment tensor. In 2-D simulations, we find a deviatoric contribution to the moment tensor, as high as 21% for near-source heterogeneities showing a 25% contrast of elastic values (relative to a homogeneous background medium). In 3-D this nonisotropic contribution reaches 27%. Second, we analyze intermediate-periods regional seismic waveforms associated with some underground nuclear explosions conducted at the Nevada National Security Site and invert for the full moment tensor, in order to quantify the relative contribution of the isotropic and deviatoric components of the tensor. The average value of the deviatoric part is about 35%. We conclude that the interactions between an explosive source and small-scale local heterogeneities of moderate amplitude may lead to a deviatoric contribution to the seismic moment, close to what is observed using regional data from nuclear test explosions.

  19. Effects of Nuclear Weapons.

    ERIC Educational Resources Information Center

    Sartori, Leo

    1983-01-01

    Fundamental principles governing nuclear explosions and their effects are discussed, including three components of a nuclear explosion (thermal radiation, shock wave, nuclear radiation). Describes how effects of these components depend on the weapon's yield, its height of burst, and distance of detonation point. Includes effects of three…

  20. Pions are neither perturbative nor nonperturbative: Wilsonian renormalization-group analysis of nuclear effective field theory including pions

    SciTech Connect

    Harada, Koji; Kubo, Hirofumi; Yamamoto, Yuki

    2011-03-15

    Nuclear effective field theory (NEFT) including pions in the two-nucleon sector is examined from the Wilsonian renormalization group point of view. The pion exchange is cut off at the floating cutoff scale, {Lambda}, with the short-distance part being represented as contact interactions in accordance with the general principle of renormalization. We derive the nonperturbative renormalization group equations in the leading order of the nonrelativistic approximation in the operator space up to including O(p{sup 2}), and find the nontrivial fixed points in the {sup 1}S{sub 0} and {sup 3}S{sub 1}-{sup 3}D{sub 1} channels which are identified with those in the pionless NEFT. The scaling dimensions, which determine the power counting, of the contact interactions at the nontrivial fixed points are also identified with those in the pionless NEFT. We emphasize the importance of the separation of the pion exchange into the short-distance and the long-distance parts, since a part of the former is nonperturbative while the latter is perturbative.

  1. Effects of nuclear war

    SciTech Connect

    von Hippel, F.

    1983-01-01

    The author reviews the subject rising the following topics and subtopics: I. Nuclear explosions: heat, nuclear radiation, and radioactive fallout; II. Effects: radiation sickness, burns, blast injuries, and equivalent areas of death; III. Nuclear war: battlefield, regional, intercontinental - counterforce, and intercontinental - counter-city and industry. There are two appendices. 34 references, 32 figures.

  2. Electron-ion recombination in nuclear recoils tracks in nonpolar liquids. Calculation of the effect of external electric field on the escape probability

    NASA Astrophysics Data System (ADS)

    Mateja, Piotr; Wojcik, Mariusz

    2016-07-01

    A computer simulation method is applied to study electron-ion recombination in tracks of low-energy nuclear recoils in nonpolar liquids in which the electron transport can be described as ideal diffusion. The electron escape probability is calculated as a function of applied electric field, both for the field parallel to the track and for the field perpendicular to the track. The dependence of escape probability on the field direction is the stronger, the longer the ionization track, with a significant effect being found already for tracks of ~100 nm length. The results are discussed in the context of possible applications of nonpolar molecular liquids as target media in directional dark matter detectors.

  3. Dynamic nuclear polarization at high magnetic fields

    PubMed Central

    Maly, Thorsten; Debelouchina, Galia T.; Bajaj, Vikram S.; Hu, Kan-Nian; Joo, Chan-Gyu; Mak–Jurkauskas, Melody L.; Sirigiri, Jagadishwar R.; van der Wel, Patrick C. A.; Herzfeld, Judith; Temkin, Richard J.; Griffin, Robert G.

    2009-01-01

    Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (μw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (γe/γl), being ∼660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields. This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (≥5 T), the regime where contemporary NMR experiments are performed. After a brief historical survey, we present a review of the classical continuous wave (cw) DNP mechanisms—the Overhauser effect, the solid effect, the cross effect, and thermal mixing. A special section is devoted to the theory of coherent polarization transfer mechanisms, since they are potentially more efficient at high fields than classical polarization schemes. The implementation of DNP at high magnetic fields has required the development and improvement of new and existing instrumentation. Therefore, we also review some recent developments in μw and probe technology, followed by an overview of DNP applications in biological solids and liquids. Finally, we outline some possible areas for future developments. PMID:18266416

  4. Using nitrogen-14 nuclear quadrupole resonance and electric field gradient information for the study of radiation effects

    SciTech Connect

    Iselin, L.H.

    1995-12-01

    Nitrogen-14 nuclear quadrupole resonance (NQR) was used in an attempt to detect the effects of ionizing radiation on organic material. Previously reported resonances for urea were detected at 2,913.32 {+-} 0.01 kHz and 2,347.88 {+-} 0.08 kHz with associated T{sub 2}* values 780 {+-} 20 {micro}s and 523 {+-} 24 {micro}s, respectively. The previously unreported {nu}{sub {minus}} line for urea-d{sup 4} was detected at 2,381 {+-} 0.04 Khz and used to determine accurately for the first time the values for the nuclear quadrupole coupling constant {chi} (3,548.74 {+-} 0.03 kHz) and the asymmetry parameter {eta} (0.31571 {+-} 0.00007) for urea-d{sup 4}. The inverse linewidth parameter T{sub 2}* for {nu}{sub +} was measured at 928 {+-} 23 {micro}s and for {nu}{sub {minus}} at 721 {+-} 12 {micro}s. Townes and Dailey analysis was performed and urea-d{sup 4} exhibits a 0.004 increase in lone pair electronic density and a slight decrease in N-H bond electronic density, as compared to urea, probably due to the mass difference. A relationship is proposed, referred to as NQR linewidth analysis, between the dynamic spin relaxation times T{sub 2} and T{sub 2}* and the widths of the distributions of the NQR parameters. Linewidth analysis is presented as a tool for possible use in future NQR work in all area, not just radiation effects. This relationship is tested using sodium nitrite T{sub 2} and T{sub 2}* values for {nu}{sub {minus}} and {nu}{sub {minus}} as a function of temperature.

  5. Radiological Effects of Nuclear War.

    ERIC Educational Resources Information Center

    Shapiro, Charles S.

    1988-01-01

    Described are the global effects of nuclear war. Discussed are radiation dosages, limited nuclear attacks, strategic arms reductions, and other results reported at the workshop on nuclear war issues in Moscow in March 1988. (CW)

  6. Nuclear saturation in lowest-order Brueckner theory with two- and three-nucleon forces in view of chiral effective field theory

    NASA Astrophysics Data System (ADS)

    Kohno, M.

    2015-12-01

    The nuclear saturation mechanism is discussed in terms of two-nucleon and three-nucleon interactions in chiral effective field theory (Ch-EFT), using the framework of lowest-order Brueckner theory. After the Coester band, which is observed in calculating saturation points with various nucleon-nucleon (NN) forces, is revisited using modern NN potentials and their low-momentum equivalent interactions, a detailed account of the saturation curve of the Ch-EFT interaction is presented. The three-nucleon force (3NF) is treated by reducing it to an effective two-body interaction by folding the third nucleon degrees of freedom. Uncertainties due to the choice of the 3NF low-energy constants c_D and c_E are discussed. The reduction of the cutoff-energy dependence of the NN potential is explained by demonstrating the effect of the 3NF in the ^1S_0 and ^3S_1 states.

  7. Nuclear spin Hall and Klein tunneling effects during oxidation with electric and magnetic field inductions in graphene.

    PubMed

    Little, Reginald B; McClary, Felicia; Rice, Bria; Jackman, Corine; Mitchell, James W

    2012-12-14

    The recent observation of the explosive oxidation of graphene with enhancement for decreasing temperature and the requirements for synchronizing oxidants for collective oxidation-reduction (redox) reactions presented a chemical scenario for the thermal harvesting by the magnetic spin Hall Effect. More experimental data are presented to demonstrate such spin Hall Effect by determining the influence of spins of so-called spectator fermionic cations. Furthermore, the so-called spectator bosonic cations are discovered to cause a Klein tunneling effect during the redox reaction of graphene. The Na(+) and K(+), fermionic cations and the Mg(2+) and Ca(2+), bosonic cations were observed and compared under a variety of experimental conditions: adiabatic reactions with initial temperatures (18-22 °C); reactions toward infinite dilution; isothermal reactions under nonadiabatic conditions at low temperature of 18 °C; reactions under paramagnetic O(2) or diamagnetic N(2) atmospheres of different permeabilities; reactions in applied and no applied external magnetic field; and reactions toward excess concentrations of common and uncommon Na(+) and Mg(2+) cations. The observed reaction kinetics and dynamics under these various, diverse conditions are consistent with the spin Hall mechanism, energy harvesting and short time violation of Second Law of Thermodynamics for redox reactions of graphene by the Na(+)K(+) mixture and are consistent with the Klein tunnel mechanism for the redox reactions of graphene by the Mg(2+)Ca(2+) mixture. Mixed spin Hall and Klein tunnel mechanisms are discovered to slow and modulate explosive redox reactions. Such spin Hall Effect also gives explanation of recent tunneling of electrons through boron nitride. PMID:23108034

  8. Shrimp processing assessed by low field nuclear magnetic resonance, near infrared spectroscopy, and physicochemical measurements--the effect of polyphosphate content and length of prebrining on shrimp muscle.

    PubMed

    Gudjónsdóttir, María; Jónsson, Ásbjörn; Bergsson, Arnljótur Bjarki; Arason, Sigurjón; Rustad, Turid

    2011-05-01

    The effect of using polyphosphates during prebrining and the effect of prebrining time of cold water shrimp (Pandalus borealis) was studied with low field nuclear magnetic resonance (LF-NMR) transverse relaxation time measurements (benchtop and unilateral) and near infrared (NIR) spectroscopy with the aim of improving shrimp processing. Strong calibrations were obtained for moisture content and water-holding capacity (WHC) using the NIR technique. Multivariate analysis indicated significant correlations between benchtop NMR parameters and moisture content and WHC, as measured with physicochemical methods and NIR spectroscopy. Significant correlations were also observed between NMR parameters and muscle pH, protein content, and phosphate content. The study showed that LF-NMR contribute to improved understanding of the shrimp brining process and to improved process control on-line or at-line, especially in combination with NIR measurements. However, optimization of the unilateral device is necessary. PMID:22417356

  9. Microscopically constrained mean-field models from chiral nuclear thermodynamics

    NASA Astrophysics Data System (ADS)

    Rrapaj, Ermal; Roggero, Alessandro; Holt, Jeremy W.

    2016-06-01

    We explore the use of mean-field models to approximate microscopic nuclear equations of state derived from chiral effective field theory across the densities and temperatures relevant for simulating astrophysical phenomena such as core-collapse supernovae and binary neutron star mergers. We consider both relativistic mean-field theory with scalar and vector meson exchange as well as energy density functionals based on Skyrme phenomenology and compare to thermodynamic equations of state derived from chiral two- and three-nucleon forces in many-body perturbation theory. Quantum Monte Carlo simulations of symmetric nuclear matter and pure neutron matter are used to determine the density regimes in which perturbation theory with chiral nuclear forces is valid. Within the theoretical uncertainties associated with the many-body methods, we find that select mean-field models describe well microscopic nuclear thermodynamics. As an additional consistency requirement, we study as well the single-particle properties of nucleons in a hot/dense environment, which affect e.g., charged-current weak reactions in neutron-rich matter. The identified mean-field models can be used across a larger range of densities and temperatures in astrophysical simulations than more computationally expensive microscopic models.

  10. Momentum dependence of the nuclear mean field

    SciTech Connect

    Baldo, M.; Bombaci, I.; Giansiracusa, G.; Lombardo, U. Dipartimento di Fisica, Universita di Catania, Corso Italia 57, 95129 Catania, Italy)

    1989-08-01

    The dependence on the momentum of the nuclear mean field is studied in the framework of the self-consistent Bethe-Brueckner theory. It is pointed out that the rearrangement term, coming from the variation of the {ital G} matrix, gives a substantial contribution at the lowest momenta. The resulting single particle potential exhibits a good rate of convergence. Its momentum dependence appears to be negligible up to 2 fm{sup {minus}1}, in contrast with potentials used in calculations of heavy-ion collisions at intermediate energies.

  11. Nuclear magnetization in gallium arsenide quantum dots at zero magnetic field

    PubMed Central

    Sallen, G.; Kunz, S.; Amand, T.; Bouet, L.; Kuroda, T.; Mano, T.; Paget, D.; Krebs, O.; Marie, X.; Sakoda, K.; Urbaszek, B.

    2014-01-01

    Optical and electrical control of the nuclear spin system allows enhancing the sensitivity of NMR applications and spin-based information storage and processing. Dynamic nuclear polarization in semiconductors is commonly achieved in the presence of a stabilizing external magnetic field. Here we report efficient optical pumping of nuclear spins at zero magnetic field in strain-free GaAs quantum dots. The strong interaction of a single, optically injected electron spin with the nuclear spins acts as a stabilizing, effective magnetic field (Knight field) on the nuclei. We optically tune the Knight field amplitude and direction. In combination with a small transverse magnetic field, we are able to control the longitudinal and transverse components of the nuclear spin polarization in the absence of lattice strain—that is, in dots with strongly reduced static nuclear quadrupole effects, as reproduced by our model calculations. PMID:24500329

  12. Effect of rock composition and texture on pore size distributions in shales: Applications in low field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Saidian, Milad

    ), and thermal maturity are the main factors that affect the reliability of a measurement technique in organic rich shales. The final step for surface relaxivity measurement is to combine the mentioned petrophysical measurement with NMR data and investigating the effect of rock composition and texture on surface relaxivity. The surface relaxivities were calculated for organic rich samples with different thermal maturity and also shales with no organic content. My results show that identification of paramagnetic minerals that affect the surface relaxivity, their content and distribution are the key factors that affect the surface relaxivity of the rock. In absence of ferromagnetic minerals, paramagnetic clays such as chlorite, illite and illite-smectite mixed layer are the main mineral groups that affect the surface relaxivity. Since clays are one of the controlling factors of rock quality and gamma ray logs respond to clays occurring in oil and gas producing formations, these logs can be used to help perform a more accurate NMR log interpretation.

  13. Quark mean field approach with derivative coupling for nuclear matter

    SciTech Connect

    Kawabata, M.; Akiyama, S.; Futami, Y.; Nakasone, T.; Yukino, T.

    2008-05-15

    We propose the quark mean field model including derivative coupling between quarks and scalar mesons in nuclear matter. This model concisely interprets an increasing size of the nucleon as well as a modification of coupling constant in the nuclear environment.

  14. In-field analysis and assessment of nuclear material

    SciTech Connect

    Morgado, R.E.; Myers, W.S.; Olivares, J.A.; Phillips, J.R.; York, R.L.

    1996-05-01

    Los Alamos National Laboratory has actively developed and implemented a number of instruments to monitor, detect, and analyze nuclear materials in the field. Many of these technologies, developed under existing US Department of Energy programs, can also be used to effectively interdict nuclear materials smuggled across or within national borders. In particular, two instruments are suitable for immediate implementation: the NAVI-2, a hand-held gamma-ray and neutron system for the detection and rapid identification of radioactive materials, and the portable mass spectrometer for the rapid analysis of minute quantities of radioactive materials. Both instruments provide not only critical information about the characteristics of the nuclear material for law-enforcement agencies and national authorities but also supply health and safety information for personnel handling the suspect materials.

  15. Nuclear oncology, a fast growing field of nuclear medicine

    NASA Astrophysics Data System (ADS)

    Olivier, Pierre

    2004-07-01

    Nuclear Medicine in oncology has been for a long time synonymous with bone scintigraphy, the first ever whole body imaging modality, and with treatment of thyroid cancer with iodine-131. More recently, somatostatin receptor scintigraphy (SRS) using peptides such as 111In-labelled octreotide became a reference imaging method in the detection and staging of neuroendocrine tumors while 131I- and 123I-MIBG remain the tracers of reference for pheochromocytomas and neuroblastomas. Lymphoscintigraphic imaging based on peritumoral injection of 99mTc-labelled colloids supports, in combination with per operative detection, the procedure of sentinel node identification in breast cancers and melanomas. Positron Emission Tomography (PET) is currently experiencing a considerable growth in oncology based on the use of 18F-FDG (fluorodeoxyglucose), a very sensitive, although non-specific, tumor tracer. Development of instrumentation is crucial in this expansion of PET imaging with new crystals being more sensitive and hybrid imagers that permit to reduce the acquisition time and offer fused PET-CT images. Current developments in therapy can be classified into three categories. Radioimmunotherapy (RIT) based on monoclonal antibodies (or fragments) labelled with beta-emitters. This technique has recently made its entrance in clinical practice with a 90Y-labelled anti-CD20 antibody ( 90Y-ibritumomab tiuxetan (Zevalin ®)) approved in US for the treatment of some subtypes of non-Hodgkin's lymphoma. Radionuclide-bone pain palliation has experienced developments with 153Sm-EDTMP, 186Re-HEDP or 89Sr, efficient in patients with widespread disease. Last, the same peptides, as those used in SRS, are being developed for therapy, labelled with 90Y, 111In or 177Lu in patients who failed to respond to other treatments. Overall, nuclear oncology is currently a fast growing field thanks to the combined developments of radiopharmaceuticals and instrumentation.

  16. Modeling nuclear field shift isotope fractionation in crystals

    NASA Astrophysics Data System (ADS)

    Schauble, E. A.

    2013-12-01

    In this study nuclear field shift fractionations in solids (and chemically similar liquids) are estimated using calibrated density functional theory calculations. The nuclear field shift effect is a potential driver of mass independent isotope fractionation(1,2), especially for elements with high atomic number such as Hg, Tl and U. This effect is caused by the different shapes and volumes of isotopic nuclei, and their interactions with electronic structures and energies. Nuclear field shift isotope fractionations can be estimated with first principles methods, but the calculations are computationally difficult, limiting most theoretical studies so far to small gas-phase molecules and molecular clusters. Many natural materials of interest are more complex, and it is important to develop ways to estimate field shift effects that can be applied to minerals, solutions, in biomolecules, and at mineral-solution interfaces. Plane-wave density functional theory, in combination with the projector augmented wave method (DFT-PAW), is much more readily adapted to complex materials than the relativistic all-electron calculations that have been the focus of most previous studies. DFT-PAW is a particularly effective tool for studying crystals with periodic boundary conditions, and may also be incorporated into molecular dynamics simulations of solutions and other disordered phases. Initial calibrations of DFT-PAW calculations against high-level all-electron models of field shift fractionation suggest that there may be broad applicability of this method to a variety of elements and types of materials. In addition, the close relationship between the isomer shift of Mössbauer spectroscopy and the nuclear field shift isotope effect makes it possible, at least in principle, to estimate the volume component of field shift fractionations in some species that are too complex even for DFT-PAW models, so long as there is a Mössbauer isotope for the element of interest. Initial results

  17. Holographic effective field theories

    NASA Astrophysics Data System (ADS)

    Martucci, Luca; Zaffaroni, Alberto

    2016-06-01

    We derive the four-dimensional low-energy effective field theory governing the moduli space of strongly coupled superconformal quiver gauge theories associated with D3-branes at Calabi-Yau conical singularities in the holographic regime of validity. We use the dual supergravity description provided by warped resolved conical geometries with mobile D3-branes. Information on the baryonic directions of the moduli space is also obtained by using wrapped Euclidean D3-branes. We illustrate our general results by discussing in detail their application to the Klebanov-Witten model.

  18. Microwave field effect transistor

    NASA Technical Reports Server (NTRS)

    Huang, Ho-Chung (Inventor)

    1989-01-01

    Electrodes of a high power, microwave field effect transistor are substantially matched to external input and output networks. The field effect transistor includes a metal ground plane layer, a dielectric layer on the ground plane layer, a gallium arsenide active region on the dielectric layer, and substantially coplanar spaced source, gate, and drain electrodes having active segments covering the active region. The active segment of the gate electrode is located between edges of the active segments of the source and drain electrodes. The gate and drain electrodes include inactive pads remote from the active segments. The pads are connected directly to the input and output networks. The source electrode is connected to the ground plane layer. The space between the electrodes and the geometry of the electrodes extablish parasitic shunt capacitances and series inductances that provide substantial matches between the input network and the gate electrode and between the output network and the drain electrode. Many of the devices are connected in parallel and share a common active region, so that each pair of adjacent devices shares the same source electrodes and each pair of adjacent devices shares the same drain electrodes. The gate electrodes for the parallel devices are formed by a continuous stripe that extends between adjacent devices and is connected at different points to the common gate pad.

  19. Nuclear effects hardened shelters

    NASA Astrophysics Data System (ADS)

    Lindke, Paul

    1990-11-01

    The Houston Fearless 76 Government Projects Group has been actively engaged for more than twenty-five years as a sub-contractor and currently as a prime contractor in the design, manufacture, repair and logistics support of custom mobile ground stations and their equipment accommodations. Other associated products include environmental control units (ECU's), mobilizers for shelters and a variety of mobile power generation units (MPU's). Since 1984, Houston Fearless 76 has designed and manufactured four 8' x 8' x 22' nuclear hardened mobile shelters. These shelters were designed to contain electronic data processing/reduction equipment. One shelter is currently being operated by the Air Force as a Defense Intelligence Agency (DIA) approved and certified Special Corrpartmented Information Facility (SCIF). During the development and manufacturing process of the shelters, we received continual technical assistance and design concept evaluations from Science Applications International Corporation (SAIC) Operations Analysis and Logistics Engineering Division and the Nondestructive Inspection Lab at McClellan AFB. SAIC was originally employed by the Air Force to design the nuclear hardening specifications applied to these shelters. The specific levels of hardening to which the shelters were designed are classified and will not be mentioned during this presentation.

  20. Local and global thermoregulatory responses to MRI electromagnetic fields: Biological effects and safety aspects of nuclear magnetic resonance imaging and spectroscopy

    SciTech Connect

    Gordon, C.J.

    1991-01-01

    During magnetic resonance imaging (MRI) procedures, a subject is exposed to three novel environmental stimuli which have drawn attention over the past decade as potential health hazards: (1) a relatively intense static magnetic field; (2) a time-varying magnetic field, and (3) a radiofrequency (RF) field. Thermoregulation is one of many physiological systems that can be affected by MRI, specifically by the RF radiation absorbed by the subject during MRI. While there is some sparse, albeit controversial data on the possible effects of static magnetic fields on thermoregulation, the major concern regarding potential health hazards of the MRI-induced thermal effects centers on the RF radiation absorbed by a subject during a scan. The purpose of the paper is to review the studies that have impacted on understanding the thermoregulatory effects of MRI with special emphasis on the problems of selecting appropriate animal models for assessing the potential risk of RF radiation exposure during MRI.

  1. Relativistic mean field model based on realistic nuclear forces

    SciTech Connect

    Hirose, S.; Serra, M.; Ring, P.; Otsuka, T.; Akaishi, Y.

    2007-02-15

    In order to predict properties of asymmetric nuclear matter, we construct a relativistic mean field (RMF) model consisting of one-meson exchange (OME) terms and point coupling (PC) terms. In order to determine the density dependent parameters of this model, we use properties of isospin symmetric nuclear matter in combination with the information on nucleon-nucleon scattering data, which are given in the form of the density dependent G-matrix derived from Brueckner calculations based on the Tamagaki potential. We show that the medium- and long-range components of this G-matrix can be described reasonably well by our effective OME interaction. In order to take into account the short-range part of the nucleon-nucleon interaction, which cannot be described well in this manner, a point coupling term is added. Its analytical form is taken from a model based on chiral perturbation theory. It contains only one additional parameter, which does not depend on the density. It is, together with the parameters of the OME potentials adjusted to the equation of state of symmetric nuclear matter. We apply this model for the investigation of asymmetric nuclear matter and find that the results for the symmetry energy as well as for the equation of state of pure neutron matter are in good agreement with either experimental data or with presently adopted theoretical predictions. In order to test the model at higher density, we use its equation of state for an investigation of properties of neutron stars.

  2. Effect of prenatal loud music and noise on total number of neurons and glia, neuronal nuclear area and volume of chick brainstem auditory nuclei, field L and hippocampus: a stereological investigation.

    PubMed

    Sanyal, Tania; Palanisamy, Pradeep; Nag, T C; Roy, T S; Wadhwa, Shashi

    2013-06-01

    The present study explores whether prenatal patterned and unpatterned sound of high sound pressure level (110 dB) has any differential effect on the morphology of brainstem auditory nuclei, field L (auditory cortex analog) and hippocampus in chicks (Gallus domesticus). The total number of neurons and glia, mean neuronal nuclear area and total volume of the brainstem auditory nuclei, field L and hippocampus of post-hatch day 1 chicks were determined in serial, cresyl violet-stained sections, using stereology software. All regions studied showed a significantly increased total volume with increase in total neuron number and mean neuronal nuclear area in the patterned music stimulated group as compared to control. Contrastingly the unpatterned noise stimulated group showed an attenuated volume with reduction in the total neuron number. The mean neuronal nuclear area was significantly reduced in the auditory nuclei and hippocampus but increased in the field L. Glial cell number was significantly increased in both experimental groups, being highest in the noise group. The brainstem auditory nuclei and field L showed an increase in glia to neuron ratio in the experimental groups as compared to control. In the hippocampus the ratio remained unaltered between control and music groups, but was higher in the noise group. It is thus evident that though the sound pressure level in both experimental groups was the same there were differential changes in the morphological parameters of the brain regions studied, indicating that the characteristics of the sound had a role in mediating these effects. PMID:23466415

  3. Nuclear effects in Neutrino Nuclear Cross-sections

    SciTech Connect

    Singh, S. K.; Athar, M. Sajjad

    2008-02-21

    Nuclear effects in the quasielastic and inelastic scattering of neutrinos(antineutrinos) from nuclear targets have been studied. The calculations are done in the local density approximation which take into account the effect of nucleon motion as well as renormalisation of weak transition strengths in the nuclear medium. The inelastic reaction leading to production of pions is calculated in a {delta} dominance model taking into account the renormalization of {delta} properties in the nuclear medium.

  4. Numerical study of the THM effects on the near-field safety of ahypothetical nuclear waste repository - BMT1 of the DECOVALEX IIIproject. Part 3: Effects of THM coupling in sparsely fracturedrocks

    SciTech Connect

    Rutqvist, J.; Chijimatsu, M.; Jing, L.; Millard, A.; Nguyen,T.S.; Rejeb, A.; Sugita, Y.; Tsang, C.F.

    2004-09-09

    BENCHPAR project, the impact of thermal-hydrological-mechanical (THM) couplings on the performance of a bentonite-back-filled nuclear waste repository in near-field crystalline rocks is evaluated in a Bench-Mark Test problem (BMT1) and the results are presented in a series of three companion papers in this issue. This is the third paper with focus on the effects of THM processes at a repository located in a sparsely fractured rock. Several independent coupled THM analyses presented in this paper show that THM couplings have the most significant impact on the mechanical stress evolution, which is important for repository design, construction and post-closure monitoring considerations. The results show that the stress evolution in the bentonite-back-filled excavations and the surrounding rock depends on the post-closure evolution of both fields of temperature and fluid pressure.It is further shown that the time required to full resaturation may play an important role for the mechanical integrity of the repository drifts.In this sense, the presence of hydraulically conducting fractures in the near-field rock might actually improve the mechanical performance of the repository. Hydraulically conducting fractures in the near-field rocks enhances the water supply to the buffers/back-fills, which promotes a more timely process of resaturation and development of swelling pressures in the back-fill, thus provides timely confining stress and support to the rock walls. In one particular case simulated in this study, it was shown that failure in the drift walls could be prevented if the compressive stresses in back-fill were fully developed within 50 years,which is when thermally induced rock strain begins to create high differential (failure-prone) stresses in the near-field rocks.

  5. Superconducting Field-Effect Transistors

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul; Romanofsky, Robert R.; Tabib-Azar, Massood

    1995-01-01

    Devices offer switching speeds greater than semiconducting counterparts. High-Tc superconducting field-effect transistors (SUPEFETs) investigated for use as electronic switches in delay-line-type microwave phase shifters. Resemble semiconductor field-effect transistors in some respects, but their operation based on different principle; namely, electric-field control of transition between superconductivity and normal conductivity.

  6. Pairing effects in nuclear dynamic

    NASA Astrophysics Data System (ADS)

    Lacroix, Denis; Scamps, Guillaume; Tanimura, Yusuke

    2016-05-01

    In recent years, efforts have been made to account for super-fluidity in time-dependent mean-field description of nuclear dynamic [1-5]. Inclusion of pairing is important to achieve a realistic description of static properties of nuclei. Here,we show that pairing can also affect the nuclear motion. State of the art TDHF approach can describe from small to large amplitude collective motion as well as the collision between nuclei. Very recently, this microscopic approach has been improved to include pairing either in the BCS or HFB framework. Recent applications of the 3D TDHF + BCS (TDHF+BCS) model introduced in [4] will be presented. The role of super-fluidity on collective motion [6, 7], on one- and two-particle transfer [8] and on fission [9, 10] will be illustrated.

  7. Global Effects of Nuclear War: A Status Report.

    ERIC Educational Resources Information Center

    Turco, R. P.; Golitsyn, G. S.

    1988-01-01

    Provided is an update on nuclear winter research based on reports made at the Moscow meeting of the Scientific Committee on Problems of the Environment (SCOPE) including early results from a major field experimentation program. Describes the development and effects of smoke produced from nuclear detonations. (CW)

  8. Effective Field Theory for Lattice Nuclei

    NASA Astrophysics Data System (ADS)

    Barnea, N.; Contessi, L.; Gazit, D.; Pederiva, F.; van Kolck, U.

    2015-02-01

    We show how nuclear effective field theory (EFT) and ab initio nuclear-structure methods can turn input from lattice quantum chromodynamics (LQCD) into predictions for the properties of nuclei. We argue that pionless EFT is the appropriate theory to describe the light nuclei obtained in LQCD simulations carried out at pion masses heavier than the physical pion mass. We solve the EFT using the effective-interaction hyperspherical harmonics and auxiliary-field diffusion Monte Carlo methods. Fitting the three leading-order EFT parameters to the deuteron, dineutron, and triton LQCD energies at mπ≈800 MeV , we reproduce the corresponding alpha-particle binding and predict the binding energies of mass-5 and mass-6 ground states.

  9. Effective field theory for lattice nuclei.

    PubMed

    Barnea, N; Contessi, L; Gazit, D; Pederiva, F; van Kolck, U

    2015-02-01

    We show how nuclear effective field theory (EFT) and ab initio nuclear-structure methods can turn input from lattice quantum chromodynamics (LQCD) into predictions for the properties of nuclei. We argue that pionless EFT is the appropriate theory to describe the light nuclei obtained in LQCD simulations carried out at pion masses heavier than the physical pion mass. We solve the EFT using the effective-interaction hyperspherical harmonics and auxiliary-field diffusion Monte Carlo methods. Fitting the three leading-order EFT parameters to the deuteron, dineutron, and triton LQCD energies at m_{π}≈800  MeV, we reproduce the corresponding alpha-particle binding and predict the binding energies of mass-5 and mass-6 ground states. PMID:25699436

  10. Modeling nuclear volume isotope effects in crystals

    PubMed Central

    Schauble, Edwin A.

    2013-01-01

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac–Hartree–Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor–crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from 119Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium

  11. Modeling nuclear volume isotope effects in crystals.

    PubMed

    Schauble, Edwin A

    2013-10-29

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac-Hartree-Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor-crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from (119)Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium. PMID

  12. Modeling nuclear volume isotope effects in crystals

    NASA Astrophysics Data System (ADS)

    Schauble, Edwin A.

    2013-10-01

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac-Hartree-Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor-crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from 119Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium.

  13. Nuclear spin effects in optical lattice clocks

    SciTech Connect

    Boyd, Martin M.; Zelevinsky, Tanya; Ludlow, Andrew D.; Blatt, Sebastian; Zanon-Willette, Thomas; Foreman, Seth M.; Ye Jun

    2007-08-15

    We present a detailed experimental and theoretical study of the effect of nuclear spin on the performance of optical lattice clocks. With a state-mixing theory including spin-orbit and hyperfine interactions, we describe the origin of the {sup 1}S{sub 0}-{sup 3}P{sub 0} clock transition and the differential g factor between the two clock states for alkaline-earth-metal(-like) atoms, using {sup 87}Sr as an example. Clock frequency shifts due to magnetic and optical fields are discussed with an emphasis on those relating to nuclear structure. An experimental determination of the differential g factor in {sup 87}Sr is performed and is in good agreement with theory. The magnitude of the tensor light shift on the clock states is also explored experimentally. State specific measurements with controlled nuclear spin polarization are discussed as a method to reduce the nuclear spin-related systematic effects to below 10{sup -17} in lattice clocks.

  14. Development and applications of NMR (nuclear magnetic resonance) in low fields and zero field

    SciTech Connect

    Bielecki, A.

    1987-05-01

    This dissertation is about nuclear magnetic resonance (NMR) spectroscopy in the absence of applied magnetic fields. NMR is usually done in large magnetic fields, often as large as can be practically attained. The motivation for going the opposite way, toward zero field, is that for certain types of materials, particularly powdered or polycrystalline solids, the NMR spectra in zero field are easier to interpret than those obtained in high field. 92 refs., 60 figs., 1 tab.

  15. Nucleosynthesis:. a Field with Still Many Open Nuclear Physics Questions

    NASA Astrophysics Data System (ADS)

    Goriely, S.

    2013-03-01

    Stellar nucleosynthesis is a vastly interdisciplinary field. There is a large number of different problems invoked calling for a variety of different and complementary research fields. Impressive progress has been made in the last decades in the various fields related to nucle-osynthesis, especially experimental and theoretical nuclear physics, as well as in ground-or space-based astronomical observations and astrophysical modelings. In spite of that success, major problems and puzzles remain. The three major nucleosynthesis processes called for to explain the origin of the elements heavier than iron are described and the major pending questions discussed. As far as nuclear physics is concerned, good quality nuclear data is known to be a necessary condition for a reliable model-ling of stellar nu-cleosynthesis. Through some specific examples, the need for further theoretical or experimental developments is also critically discussed in view of their impact on nucleosynthesis predictions.

  16. Nucleosynthesis: a field with still many open nuclear physics questions

    SciTech Connect

    Goriely, S.

    2010-06-01

    Stellar nucleosynthesis is a vastly interdisciplinary field. There is a large number of different problems invoked calling for a variety of different and complementary research fields. Impressive progress has been made for the last decades in the various fields related to nucleosynthesis, especially in experimental and theoretical nuclear physics, as well as in ground-based or space astronomical observations and astrophysical modellings. In spite of that success, major problems and puzzles remain. The three major nucleosynthesis processes called for to explain the origin of the elements heavier than iron are described and the major pending questions discussed. As far as nuclear physics is concerned, good quality nuclear data is known to be a necessary condition for a reliable modelling of stellar nucleosynthesis. Through some specific examples, the need for further theoretical or experimental developments is also critically discussed in view of their impact on nucleosynthesis predictions.

  17. Nuclear size effects in vibrational spectra.

    PubMed

    Almoukhalalati, Adel; Shee, Avijit; Saue, Trond

    2016-06-01

    We present a theoretical study of nuclear volume in the rovibrational spectra of diatomic molecules which is an extension of a previous study restricted to rotational spectra [Chem. Phys., 2012, 401, 103]. We provide a new derivation for the electron-nucleus electrostatic interaction energy which is basically independent of the choice of model for the nuclear charge distribution. Starting from this expression we derive expressions for the electronic, rotational and vibrational field shift parameters in terms of effective electron density and its first and second derivatives with respect to internuclear distance. The effective density is often approximated by the contact density, but we demonstrate that this leads to errors on the order of 10% and is furthermore not necessary since the contact and effective densities can be obtained at the same computational cost. We calculate the field shift parameters at the 4-component relativistic coupled-cluster singles-and-doubles level and find that our results confirm the experimental findings of Tiemann and co-workers [Chem. Phys., 1982, 68(21), 1982, Ber. Bunsenges. Phys. Chem., 1982, 86, 821], whereas we find no theoretical justification for a scaling factor introduced in later work [Chem. Phys., 1985, 93, 349]. For lead sulfide we study the effective density as a function of internuclear distance and find a minimum some 0.2 Å inside the equilibrium bond distance. We also discuss Bigeleisen-Goeppert-Mayer theory of isotope fractionation in light of our results. PMID:27215395

  18. Desktop fast-field cycling nuclear magnetic resonance relaxometer.

    PubMed

    Sousa, Duarte Mesquita; Marques, Gil Domingos; Cascais, José Manuel; Sebastião, Pedro José

    2010-07-01

    In this paper a new type of Fast Field Cycling (FFC) Nuclear Magnetic Resonance (NMR) relaxometer with low power consumption (200W) and cycle to cycle field stability better than 10(-4) is described. The new high-permeability magnet was designed to allow for good magnetic field homogeneity and allows for the sample rotation around an axis perpendicular to magnetic field, operating with magnetic fields between 0 and 0.21T. The power supply of the new relaxometer was specially developed in order to have steady state accurate currents and allow for magnetic field switching times less than 3ms. Additional control circuits were developed and included to compensate the Earth magnetic field component parallel to the field axis and to compensate for parasitic currents. The main aspects of the developed circuits together with some calibrating experimental results using the liquid crystal compounds 5CB and 8CB are presented and discussed. PMID:20688489

  19. The field treatment of the nuclear spectrum. Historical foundation and two contributions to its ensuing development

    NASA Astrophysics Data System (ADS)

    Bes, Daniel R.

    2016-06-01

    The highlights of the model which was developed during the 1950s at the Niels Bohr Institute, Copenhagen, under the leadership of Aage Bohr and Ben Mottelson, are described in this contribution. Subsequently, it is shown that the field concept—the fundamental tool of the unified model—is not only an intelligent guess to describe the difficult many-body nuclear system. By means of a systematic expansion of field-coupling effects, the nuclear field theory (NFT) accounts for the overcompleteness of the initial product basis and the overlooking of the Pauli principle acting between constituents of the basis. Eventually it leads to the exact solution of the nuclear many-body problem. The description in terms of fields involves another problem if the field violates a symmetry inherent to the initial problem. The solution is borrowed from the BRST treatments of gauge systems, in which the lost symmetry is replaced by a more powerful one.

  20. Nuclear reaction cross sections of exotic nuclei in the Glauber model for relativistic mean field densities

    SciTech Connect

    Patra, S. K.; Panda, R. N.; Arumugam, P.; Gupta, Raj K.

    2009-12-15

    We have calculated the total nuclear reaction cross sections of exotic nuclei in the framework of the Glauber model, using as inputs the standard relativistic mean field (RMF) densities and the densities obtained from the more recently developed effective-field-theory-motivated RMF (the E-RMF). Both light and heavy nuclei are taken as the representative targets, and the light neutron-rich nuclei as projectiles. We found the total nuclear reaction cross section to increase as a function of the mass number, for both the target and projectile nuclei. The differential nuclear elastic scattering cross sections are evaluated for some selected systems at various incident energies. We found a large dependence of the differential elastic scattering cross section on incident energy. Finally, we have applied the same formalism to calculate both the total nuclear reaction cross section and the differential nuclear elastic scattering cross section for the recently discussed superheavy nucleus with atomic number Z=122.

  1. Effects of exposure to gradient magnetic fields emitted by nuclear magnetic resonance devices on clonogenic potential and proliferation of human hematopoietic stem cells.

    PubMed

    Iachininoto, Maria Grazia; Camisa, Vincenzo; Leone, Lucia; Pinto, Rosanna; Lopresto, Vanni; Merla, Caterina; Giorda, Ezio; Carsetti, Rita; Zaffina, Salvatore; Podda, Maria Vittoria; Teofili, Luciana; Grassi, Claudio

    2016-05-01

    This study investigates effects of gradient magnetic fields (GMFs) emitted by magnetic resonance imaging (MRI) devices on hematopoietic stem cells. Field measurements were performed to assess exposure to GMFs of staff working at 1.5 T and 3 T MRI units. Then an exposure system reproducing measured signals was realized to expose in vitro CD34+ cells to GMFs (1.5 T-protocol and 3 T-protocol). CD34+ cells were obtained by Fluorescence Activated Cell Sorting from six blood donors and three MRI-exposed workers. Blood donor CD34+ cells were exposed in vitro for 72 h to 1.5 T or 3 T-protocol and to sham procedure. Cells were then cultured and evaluated in colony forming unit (CFU)-assay up to 4 weeks after exposure. Results showed that in vitro GMF exposure did not affect cell proliferation but instead induced expansion of erythroid and monocytes progenitors soon after exposure and for the subsequent 3 weeks. No decrease of other clonogenic cell output (i.e., CFU-granulocyte/erythroid/macrophage/megakaryocyte and CFU-granulocyte/macrophage) was noticed, nor exposed CD34+ cells underwent the premature exhaustion of their clonogenic potential compared to sham-exposed controls. On the other hand, pilot experiments showed that CD34+ cells exposed in vivo to GMFs (i.e., samples from MRI workers) behaved in culture similarly to sham-exposed CD34+ cells, suggesting that other cells and/or microenvironment factors might prevent GMF effects on hematopoietic stem cells in vivo. Accordingly, GMFs did not affect the clonogenic potential of umbilical cord blood CD34+ cells exposed in vitro together with the whole mononuclear cell fraction. PMID:26992028

  2. Numerical investigations on a compact magnetic fusion device for studying the effect of external applied magnetic field oscillations on the nuclear burning efficiency of D-T and p-11B fuels

    NASA Astrophysics Data System (ADS)

    Moustaizis, S. D.; Lalousis, P.; Hora, H.; Larour, J.; Auvray, P.; Balcou, P.; Ducret, J.-E.; Martin, P.

    2015-05-01

    The burning process of high density (about 1018cm-3), high temperature (tens to hundreds of keV) plasma trapped by a high mirror-like magnetic field in a Compact Magnetic Fusion (CMF) device is numerically investigated.. The initial high density and high temperature plasma in the CMF device is produced by ultrashort high intensity laser beam interaction with clusters or thin foils, and two fuels, D-T and p-11B are studied. The spatio-temporal evolution of D-T and p-11B plasmas, the production of alphas, the generated electric fields and the high external applied magnetic field are described by a 1-D multifluid code. The initial values for the plasma densities, temperatures and external applied magnetic field (about 100 T) correspond to high β plasmas. The main objectives of the numerical simulations are: to study the plasma trapping, the neutron and alpha production for both fuels, and compare the effect of the external applied magnetic field on the nuclear burning efficiency for the two fuels.. The comparisons and the advantages for each fuel will be presented. The proposed CMF device and the potential operation of the device within the ELI-NP pillar will be discussed.

  3. Effective Giromagnetic Ratios in Artifical Nuclear Magnetization Pumping of the Noble Gases Mix

    NASA Astrophysics Data System (ADS)

    Popov, E. N.; Barantsev, K. A.; Litvinov, A. N.

    2015-09-01

    Dynamic of the nuclear magnetization of the two noble gases mix was studied in this research. Nuclear magnetization pumped along the induction of external magnetic field. Vector of nuclear magnetization is given a tilt by the week rotational magnetic field, which makes NMR for noble gases. Interaction between the nuclear magnetic moments of the different noble gases adducted to shifts at the frequency of nuclear moments precession in external magnetic field. Effective gyromagnetic ratios of the nuclear of noble gases is defined and it different from the tabulated value. There is theoretical calculation of effective gyromagnetic ratios in this research.

  4. The Active Field of Nuclear and Radiochemistry: Not Just Nuclear Power.

    PubMed

    Walther, Clemens

    2016-08-01

    " … The number of universities teaching nuclear and radiochemistry has decreased, not least as radiochemistry is erroneously linked to the use of nuclear power … Radiochemistry is essential for a variety of fields, including radiopharmaceuticals, as well as the management of radioactive waste … we are facing a lack of specialists in the area of radiation protection …" Read more in the Editorial by Clemens Walther. PMID:27321863

  5. Nuclear and extranuclear effects of vitamin A.

    PubMed

    Iskakova, Madina; Karbyshev, Mikhail; Piskunov, Aleksandr; Rochette-Egly, Cécile

    2015-12-01

    Vitamin A or retinol is a multifunctional vitamin that is essential at all stages of life from embryogenesis to adulthood. Up to now, it has been accepted that the effects of vitamin A are exerted by active metabolites, the major ones being 11-cis retinal for vision, and all trans-retinoic acid (RA) for cell growth and differentiation. Basically RA binds nuclear receptors, RARs, which regulate the expression of a battery of target genes in a ligand dependent manner. During the last decade, new scenarios have been discovered, providing a rationale for the understanding of other long-noted but not explained functions of retinol. These novel scenarios involve: (i) other nuclear receptors such as PPAR β/δ, which regulate the expression of other target genes with other functions; (ii) extranuclear and nontranscriptional effects, such as the activation of kinases, which phosphorylate RARs and other transcription factors, thus expanding the list of the RA-activated genes; (iii) finally, vitamin A is active per se and can work as a cytokine that regulates gene transcription by activating STRA6. New effects of vitamin A and RA are continuously being discovered in new fields, revealing new targets and new mechanisms thus improving the understanding the pleiotropicity of their effects. PMID:26459513

  6. Characterization of polymer networks using the dipolar correlation effect on the stimulated echo and field-cycling nuclear-magnetic resonance relaxometry

    NASA Astrophysics Data System (ADS)

    Fischer, Elmar; Grinberg, Farida; Kimmich, Rainer; Hafner, Siegfried

    1998-07-01

    Chain dynamics in a series of styrene-butadiene rubbers (SBR) was studied with the aid of the dipolar correlation effect (DCE) and field-cycling NMR relaxometry (FCR). The typical time scales of the two techniques are t>10-4 s and t<10-3 s, respectively, and therefore complementary. The crosslink density of the polymer networks was varied in a wide range. In order to prevent sinusoidal undulations of the stimulated-echo attenuation curves due to spin exchange between groups with different chemical-shift offsets, the DCE of the samples was examined using a modified radio frequency pulse sequence with additional π pulses inserted in the free-evolution intervals. Residual dipolar couplings can thus be probed in samples where chemical-shift and dipolar interactions are of the same order. The dipolar correlations probed with the DCE in SBR networks turned out to exist on a time scale exceeding 300 ms. The short-time fluctuations (probed by FCR) and the long-time dynamics (probed by DCE) can be approached by power-law dipolar correlation functions with exponents -0.78±0.02 and -1.5±0.1, respectively. The crossover time is in the order of 1 ms. In contrast to FCR, the DCE data strongly depend on the crosslink density but not on the temperature in a range from 30 to 80 °C. On this basis determinations of the crosslink density may be possible as an alternative to the usual mechanical torsion modulus measurements.

  7. Dynamic nuclear polarization in the hyperfine-field-dominant region

    NASA Astrophysics Data System (ADS)

    Lee, Seong-Joo; Shim, Jeong Hyun; Kim, Kiwoong; Yu, Kwon Kyu; Hwang, Seong-min

    2015-06-01

    Dynamic nuclear polarization (DNP) allows measuring enhanced nuclear magnetic resonance (NMR) signals. Though the efficiency of DNP has been known to increase at low fields, the usefulness of DNP has not been throughly investigated yet. Here, using a superconducting quantum interference device-based NMR system, we performed a series of DNP experiments with a nitroxide radical and measured DNP spectra at several magnetic fields down to sub-microtesla. In the DNP spectra, the large overlap of two peaks having opposite signs results in net enhancement factors, which are significantly lower than theoretical expectations [30] and nearly invariant with respect to magnetic fields below the Earth's field. The numerical analysis based on the radical's Hamiltonian provides qualitative explanations of such features. The net enhancement factor reached 325 at maximum experimentally, but our analysis reveals that the local enhancement factor at the center of the rf coil is 575, which is unaffected by detection schemes. We conclude that DNP in the hyperfine-field-dominant region yields sufficiently enhanced NMR signals at magnetic fields above 1 μ T.

  8. Effective Field Theories, Reductionism and Scientific Explanation

    NASA Astrophysics Data System (ADS)

    Hartmann, Stephan

    Effective field theories have been a very popular tool in quantum physics for almost two decades. And there are good reasons for this. I will argue that effective field theories share many of the advantages of both fundamental theories and phenomenological models, while avoiding their respective shortcomings. They are, for example, flexible enough to cover a wide range of phenomena, and concrete enough to provide a detailed story of the specific mechanisms at work at a given energy scale. So will all of physics eventually converge on effective field theories? This paper argues that good scientific research can be characterised by a fruitful interaction between fundamental theories, phenomenological models and effective field theories. All of them have their appropriate functions in the research process, and all of them are indispensable. They complement each other and hang together in a coherent way which I shall characterise in some detail. To illustrate all this I will present a case study from nuclear and particle physics. The resulting view about scientific theorising is inherently pluralistic, and has implications for the debates about reductionism and scientific explanation.

  9. Mechanism of dynamic nuclear polarization in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Farrar, C. T.; Hall, D. A.; Gerfen, G. J.; Inati, S. J.; Griffin, R. G.

    2001-03-01

    Solid-state NMR signal enhancements of about two orders of magnitude (100-400) have been observed in dynamic nuclear polarization (DNP) experiments performed at high magnetic field (5 T) and low temperature (10 K) using the nitroxide radical 4-amino TEMPO as the source of electron polarization. Since the breadth of the 4-amino TEMPO EPR spectrum is large compared to the nuclear Larmor frequency, it has been assumed that thermal mixing (TM) is the dominate mechanism by which polarization is transferred from electron to nuclear spins. However, theoretical explanations of TM generally assume a homogeneously broadened EPR line and, since the 4-amino TEMPO line at 5 T is inhomogeneously broadened, they do not explain the observed DNP enhancements. Accordingly, we have developed a treatment of DNP that explicitly uses electron-electron cross-relaxation to mediate electron-nuclear polarization transfer. The process proceeds via spin flip-flops between pairs of electronic spin packets whose Zeeman temperatures differ from one another. To confirm the essential features of the model we have studied the field dependence of electron-electron double resonance (ELDOR) data and DNP enhancement data. Both are well simulated using a simple model of electron cross-relaxation in the inhomogeneously broadened 4-amino TEMPO EPR line.

  10. Neutron star cooling: A challenge to the nuclear mean field

    SciTech Connect

    Hoang Sy Than; Nguyen Van Giai

    2009-12-15

    The two recent density-dependent versions of the finite-range M3Y interaction (CDM3Yn and M3Y-Pn) have been probed against the bulk properties of asymmetric nuclear matter (NM) in the nonrelativistic Hartree-Fock (HF) formalism. The same HF study has also been done with the famous Skyrme (SLy4) and Gogny (D1S and D1N) interactions that were well tested in the nuclear structure calculations. Our HF results are compared with those given by other many-body calculations like the Dirac-Brueckner Hartree-Fock approach or ab initio variational calculations using free nucleon-nucleon interaction and by both the nonrelativistic and relativistic mean-field studies using different model parameters. Although the two considered density-dependent versions of the M3Y interaction were proven to be quite realistic in the nuclear structure or reaction studies, they give two distinct behaviors of the NM symmetry energy at high densities, like the Asy-soft and Asy-stiff scenarios found earlier with other mean-field interactions. As a consequence, we obtain two different behaviors of the proton fraction in the {beta}-equilibrium that in turn can imply two drastically different mechanisms for the neutron star cooling. While some preference of the Asy-stiff scenario was found based on predictions of the latest microscopic many-body calculations or empirical NM pressure and isospin diffusion data deduced from heavy-ion collisions, a consistent mean-field description of nuclear structure database is more often given by some Asy-soft type interaction like the Gogny or M3Y-Pn ones. Such a dilemma poses an interesting challenge to the modern mean-field approaches.

  11. Stochastic Mean-Field Dynamics For Nuclear Collisions

    SciTech Connect

    Ayik, Sakir

    2008-11-11

    We discuss a stochastic approach to improve description of nuclear dynamics beyond the mean-field approximation at low energies. For small amplitude fluctuations, this approach gives a result for the dispersion of a one-body observable that is identical to the result obtained previously through a variational approach. Furthermore, it incorporates one-body dissipation and fluctuation mechanisms in accordance with quantal fluctuation-dissipation relation.

  12. Radiation Effects in Nuclear Waste Materials

    SciTech Connect

    William j. Weber; Lumin Wang; Jonathan Icenhower

    2004-07-09

    The objective of this project is to develop a fundamental understanding of radiation effects in glasses and ceramics, as well as the influence of solid-state radiation effects on aqueous dissolution kinetics, which may impact the performance of nuclear waste forms and stabilized nuclear materials.

  13. Nuclear Weapons Effects (Self-Teaching Materials).

    ERIC Educational Resources Information Center

    Defense Civil Preparedness Agency (DOD), Battle Creek, MI.

    Developed by the Civil Defense Preparedness Agency, this autoinstructional text deals with nuclear weapons effects. The destructive effects of an atomic blast are first introduced, and then long-term radioactive consequences are stressed. (CP)

  14. Nuclear magnetic resonance at millitesla fields using a zero-field spectrometer.

    PubMed

    Tayler, Michael C D; Sjolander, Tobias F; Pines, Alexander; Budker, Dmitry

    2016-09-01

    We describe new analytical capabilities for nuclear magnetic resonance (NMR) experiments in which signal detection is performed with chemical resolution (via spin-spin J couplings) in the zero to ultra-low magnetic field region, below 1μT. Using magnetic fields in the 100μT to 1mT range, we demonstrate the implementation of conventional NMR pulse sequences with spin-species selectivity. PMID:27391123

  15. Nuclear magnetic resonance at millitesla fields using a zero-field spectrometer

    NASA Astrophysics Data System (ADS)

    Tayler, Michael C. D.; Sjolander, Tobias F.; Pines, Alexander; Budker, Dmitry

    2016-09-01

    We describe new analytical capabilities for nuclear magnetic resonance (NMR) experiments in which signal detection is performed with chemical resolution (via spin-spin J couplings) in the zero to ultra-low magnetic field region, below 1 μT. Using magnetic fields in the 100 μT to 1 mT range, we demonstrate the implementation of conventional NMR pulse sequences with spin-species selectivity.

  16. Phase transitions of nuclear matter beyond mean field theory

    SciTech Connect

    Tran Huu Phat; Nguyen Tuan Anh; Nguyen Van Long; Le Viet Hoa

    2007-10-15

    The Cornwall-Jackiw-Tomboulis (CJT) effective action approach is applied to study the phase transition of nuclear matter modeled by the four-nucleon interaction. It is shown that in the Hartree-Fock approximation (HFA) a first-order phase transition takes place at low temperature, whereas the phase transition is of second order at higher temperature.

  17. Relativistic mean-field models and nuclear matter constraints

    SciTech Connect

    Dutra, M.; Lourenco, O.; Carlson, B. V.; Delfino, A.; Menezes, D. P.; Avancini, S. S.; Stone, J. R.; Providencia, C.; Typel, S.

    2013-05-06

    This work presents a preliminary study of 147 relativistic mean-field (RMF) hadronic models used in the literature, regarding their behavior in the nuclear matter regime. We analyze here different kinds of such models, namely: (i) linear models, (ii) nonlinear {sigma}{sup 3}+{sigma}{sup 4} models, (iii) {sigma}{sup 3}+{sigma}{sup 4}+{omega}{sup 4} models, (iv) models containing mixing terms in the fields {sigma} and {omega}, (v) density dependent models, and (vi) point-coupling ones. In the finite range models, the attractive (repulsive) interaction is described in the Lagrangian density by the {sigma} ({omega}) field. The isospin dependence of the interaction is modeled by the {rho} meson field. We submit these sets of RMF models to eleven macroscopic (experimental and empirical) constraints, used in a recent study in which 240 Skyrme parametrizations were analyzed. Such constraints cover a wide range of properties related to symmetric nuclear matter (SNM), pure neutron matter (PNM), and both SNM and PNM.

  18. Effective citizen advocacy of beneficial nuclear technologies

    SciTech Connect

    McKibben, J. Malvyn; Wood, Susan

    2007-07-01

    In 1991, a small group of citizens from communities near the Savannah River Site (SRS) formed a pro-nuclear education and advocacy group, Citizens for Nuclear Technology Awareness (CNTA). Their purpose was to: (1) counter nuclear misinformation that dominated the nation's news outlets, (2) provide education on nuclear subjects to area citizens, students, elected officials, and (3) provide informed citizen support for potential new missions for SRS when needed. To effectively accomplish these objectives it is also essential to establish and maintain good relations with community leaders and reporters that cover energy and nuclear subjects. The organization has grown considerably since its inception and has expanded its sphere of influence. We believe that our experiences over these fifteen years are a good model for effectively communicating nuclear subjects with the public. This paper describes the structure, operation and some of the results of CNTA. (authors)

  19. Rearranging Pionless Effective Field Theory

    SciTech Connect

    Martin Savage; Silas Beane

    2001-11-19

    We point out a redundancy in the operator structure of the pionless effective field theory which dramatically simplifies computations. This redundancy is best exploited by using dibaryon fields as fundamental degrees of freedom. In turn, this suggests a new power counting scheme which sums range corrections to all orders. We explore this method with a few simple observables: the deuteron charge form factor, n p -> d gamma, and Compton scattering from the deuteron. Higher dimension operators involving electroweak gauge fields are not renormalized by the s-wave strong interactions, and therefore do not scale with inverse powers of the renormalization scale. Thus, naive dimensional analysis of these operators is sufficient to estimate their contribution to a given process.

  20. Inflating with large effective fields

    SciTech Connect

    Burgess, C.P.; Cicoli, M.; Quevedo, F.; Williams, M. E-mail: mcicoli@ictp.it E-mail: mwilliams@perimeterinsititute.ca

    2014-11-01

    We re-examine large scalar fields within effective field theory, in particular focussing on the issues raised by their use in inflationary models (as suggested by BICEP2 to obtain primordial tensor modes). We argue that when the large-field and low-energy regimes coincide the scalar dynamics is most effectively described in terms of an asymptotic large-field expansion whose form can be dictated by approximate symmetries, which also help control the size of quantum corrections. We discuss several possible symmetries that can achieve this, including pseudo-Goldstone inflatons characterized by a coset G/H (based on abelian and non-abelian, compact and non-compact symmetries), as well as symmetries that are intrinsically higher dimensional. Besides the usual trigonometric potentials of Natural Inflation we also find in this way simple large-field power laws (like V ∝ φ{sup 2}) and exponential potentials, V(φ) = ∑{sub k}V{sub x}e{sup −kφ/M}. Both of these can describe the data well and give slow-roll inflation for large fields without the need for a precise balancing of terms in the potential. The exponential potentials achieve large r through the limit |η| || ε and so predict r ≅ (8/3)(1-n{sub s}); consequently n{sub s} ≅ 0.96 gives r ≅ 0.11 but not much larger (and so could be ruled out as measurements on r and n{sub s} improve). We examine the naturalness issues for these models and give simple examples where symmetries protect these forms, using both pseudo-Goldstone inflatons (with non-abelian non-compact shift symmetries following familiar techniques from chiral perturbation theory) and extra-dimensional models.

  1. DC superconducting quantum interference device usable in nuclear quadrupole resonance and zero field nuclear magnetic spectrometers

    DOEpatents

    Fan, N.Q.; Clarke, J.

    1993-10-19

    A spectrometer for measuring the nuclear quadrupole resonance spectra or the zero-field nuclear magnetic resonance spectra generated by a sample is disclosed. The spectrometer uses an amplifier having a dc SQUID operating in a flux-locked loop for generating an amplified output as a function of the intensity of the signal generated by the sample. The flux-locked loop circuit includes an integrator. The amplifier also includes means for preventing the integrator from being driven into saturation. As a result, the time for the flux-locked loop to recover from the excitation pulses generated by the spectrometer is reduced. 7 figures.

  2. DC superconducting quantum interference device usable in nuclear quadrupole resonance and zero field nuclear magnetic spectrometers

    DOEpatents

    Fan, Non Q.; Clarke, John

    1993-01-01

    A spectrometer for measuring the nuclear quadrupole resonance spectra or the zero-field nuclear magnetic resonance spectra generated by a sample is disclosed. The spectrometer uses an amplifier having a dc SQUID operating in a flux-locked loop for generating an amplified output as a function of the intensity of the signal generated by the sample. The flux-locked loop circuit includes an integrator. The amplifier also includes means for preventing the integrator from being driven into saturation. As a result, the time for the flux-locked loop to recover from the excitation pulses generated by the spectrometer is reduced.

  3. High Field Dynamic Nuclear Polarization NMR with Surfactant Sheltered Biradicals

    PubMed Central

    2015-01-01

    We illustrate the ability to place a water-insoluble biradical, bTbk, into a glycerol/water matrix with the assistance of a surfactant, sodium octyl sulfate (SOS). This surfactant approach enables a previously water insoluble biradical, bTbk, with favorable electron–electron dipolar coupling to be used for dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) experiments in frozen, glassy, aqueous media. Nuclear Overhauser enhancement (NOE) and paramagnetic relaxation enhancement (PRE) experiments are conducted to determine the distribution of urea and several biradicals within the SOS macromolecular assembly. We also demonstrate that SOS assemblies are an effective approach by which mixed biradicals are created through an assembly process. PMID:24506193

  4. Radiation tolerant silicon nitride insulated gate field effect transistors

    NASA Technical Reports Server (NTRS)

    Newman, P. A.

    1969-01-01

    Metal-Insulated-Semiconductor Field Effect Transistor /MISFET/ device uses a silicon nitride passivation layer over a thin silicon oxide layer to enhance the radiation tolerance. It is useful in electronic systems exposed to space radiation environment or the effects of nuclear weapons.

  5. New methodology for use in rotating field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Jachman, Rebecca Corina

    High-resolution NMR spectra of samples with anisotropic broadening are simplified to their isotropic spectra by fast rotation of the sample at the magic angle 54.7°. This dissertation concerns the development of novel Nuclear Magnetic Resonance (NMR) methodologies which would rotate the magnetic field instead of the sample, i.e. rotating field NMR. It also provides an overview of the NMR concepts, procedures, and experiments needed to understand the methodologies that will be used for rotating field NMR. A simple two-dimensional shimming method based on harmonic corrector rings provides arbitrary multiple order shimming corrections that are necessary for rotating field systems, but can be used in shimming other systems as well. Those results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to a factor of ten. An additional order of magnitude reduction is in principle achievable by utilizing this shimming method for z-gradient correction and higher order xy gradients. Additionally, initial investigations into a specialized pulse sequence for the rotating field NMR experiment, which allows for spinning at angles other than the magic angle and spinning slower than the anisotropic broadening is discussed. This will be useful for rotating field NMR because there are limits on how fast a field can be spun and difficulties of reaching the magic angle. This pulse sequence is a combination of the previously established projected magic angle spinning (p-MAS) and magic angle turning (MAT) pulse sequences. One of the goals of this project is for rotating field NMR to be used on biological systems. The p-MAS pulse sequence was successfully tested on bovine tissue samples, which suggests that it will be a viable methodology to use in rotating field NMR. A side experiment on steering magnetic particles by MRI gradients was also carried out. Initial investigations indicate some movement, but for total steering control, further experiments are

  6. Nuclear versus nucleon structure effects on nuclear transparency

    SciTech Connect

    O. Benhar

    1997-06-25

    Nuclear structure effects account for the observed enhancement of the nuclear transparency to moderate energy protons, with respect to the predictions of Glauber theory. This enhancement appears to be comparable to the one associated with the onset of color transparency in the Q2 range spanned by the available (e,e'p) data (Q2 < 7 (GeV/c)2). It is argued that in this kinematical regime a stronger colour transparency signal can be observed in the low energy loss tail of the inclusive electron-nucleus cross section, corresponding to large values of the Bjorken scaling variable x (x>2).

  7. Process dependent nuclear k⊥ broadening effect

    NASA Astrophysics Data System (ADS)

    Schäfer, Andreas; Zhou, Jian

    2013-10-01

    We study the process dependent nuclear k⊥ broadening effect by employing the transverse momentum dependent (TMD) factorization approach in combination with the Mclerran-Venugopalan model. More specifically, we investigate how the parton transverse momentum distributions are affected by the process dependent gauge links in cold nuclear matter. In particular, our analysis also applies to the polarized cases including the nuclear quark Boer-Mulders function and the linearly polarized gluon distribution. Our main focus is on the nuclear TMDs at intermediate or large x.

  8. The environmental effects of nuclear war

    SciTech Connect

    MacCracken, M.C.

    1988-09-01

    Substantial environmental disruption will significantly add to the disastrous consequences caused by the direct thermal, blast, and radiological effects brought on by a major nuclear war. Local fallout could cover several percent of the Northern Hemisphere with potentially lethal doses. Smoke from post-nuclear fires could darken the skies and induce temperature decreases of tens of degrees in continental interiors. Stratospheric ozone could be significantly reduced due to nitric oxide injections and smoke-induced circulation changes. The environmental effects spread the consequences of a nuclear war to the world population, adding to the potentially large disruptive effects a further reason to avoid such a catastrophe. 27 refs., 4 figs.

  9. A Novel Variable Field System for Field-Cycled Dynamic Nuclear Polarization Spectroscopy

    PubMed Central

    Shet, Keerthi; Caia, George L.; Kesselring, Eric; Samouilov, Alexandre; Petryakov, Sergey; Lurie, David J.; Zweier, Jay L.

    2014-01-01

    Dynamic nuclear polarization (DNP) is an NMR-based technique which enables detection and spectral characterization of endogenous and exogenous paramagnetic substances measured via transfer of polarization from the saturated unpaired electron spin system to the NMR active nuclei. A variable field system capable of performing DNP spectroscopy with NMR detection at any magnetic field in the range 0 - 0.38 T is described. The system is built around a clinical open-MRI system. To obtain EPR spectra via DNP, partial cancellation of the detection field B0NMR is required to alter the evolution field B0EPR at which the EPR excitation is achieved. The addition of resistive actively shielded field cancellation coils in the gap of the primary magnet provides this field offset in the range of 0–100 mT. A description of the primary magnet, cancellation coils, power supplies, interfacing hardware, RF electronics and console are included. Performance of the instrument has been evaluated by acquiring DNP spectra of phantoms with aqueous nitroxide solutions (TEMPOL) at three NMR detection fields of 97 G, 200 G and 587 G corresponding to 413 kHz, 851.6 kHz and 2.5 MHz respectively and fixed EPR evolution field of 100 G corresponding to an irradiation frequency of 282.3 MHz. This variable field DNP system offers great flexibility for the performance of DNP spectroscopy with independent optimum choice of EPR excitation and NMR detection fields. PMID:20570197

  10. Unstable infinite nuclear matter in stochastic mean field approach

    SciTech Connect

    Colonna, M.; Chomaz, P. Laboratorio Nazionale del Sud, Viale Andrea Doria, Catania )

    1994-04-01

    In this article, we consider a semiclassical stochastic mean-field approach. In the case of unstable infinite nuclear matter, we calculate the characteristic time of the exponential growing of fluctuations and the diffusion coefficients associated to the unstable modes, in the framework of the Boltzmann-Langevin theory. These two quantities are essential to describe the dynamics of fluctuations and instabilities since, in the unstable regions, the evolution of the system will be dominated by the amplification of fluctuations. In order to make realistic 3D calculations feasible, we suggest to replace the complicated Boltzmann-Langevin theory by a simpler stochastic mean-field approach corresponding to a standard Boltzmann evolution, complemented by a simple noise chosen to reproduce the dynamics of the most unstable modes. Finally we explain how to approximately implement this method by simply tuning the noise associated to the use of a finite number of test particles in Boltzman-like calculations.

  11. Rotational Doppler Effect and Barnett Field in Spinning NMR

    NASA Astrophysics Data System (ADS)

    Chudo, Hiroyuki; Harii, Kazuya; Matsuo, Mamoru; Ieda, Jun'ichi; Ono, Masao; Maekawa, Sadamichi; Saitoh, Eiji

    2015-04-01

    We report the observation of the rotational Doppler effect using nuclear magnetic resonance (NMR). We have developed a coil-spinning technique that enables measurements by rotating a detector and fixing a sample. We found that the rotational Doppler effect gives rise to NMR frequency shifts equal to the rotation frequency. We formulate the rotational Doppler effect and the Barnett field using a vector model for the nuclear magnetic moment. This formulation reveals that, with just the sample rotating, both effects cancel each other, thereby explaining the absence of an NMR frequency shift in conventional sample-spinning NMR measurements.

  12. Solid effect in magic angle spinning dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Corzilius, Björn; Smith, Albert A.; Griffin, Robert G.

    2012-08-01

    For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ω _0 ^{ - 2} field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ɛ = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of 1H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear 1H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect.

  13. Solid effect in magic angle spinning dynamic nuclear polarization

    PubMed Central

    Corzilius, Björn; Smith, Albert A.; Griffin, Robert G.

    2012-01-01

    For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}\\omega _0 ^{ - 2}\\end{equation*} \\end{document}ω0−2 field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ɛ = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of 1H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear 1H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements

  14. Solid effect in magic angle spinning dynamic nuclear polarization.

    PubMed

    Corzilius, Björn; Smith, Albert A; Griffin, Robert G

    2012-08-01

    For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ω(0)(-2) field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ε = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of (1)H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear (1)H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect. PMID:22894339

  15. Nuclear effects in neutrino oscillation experiments

    SciTech Connect

    Chauhan, S.; Athar, M. Sajjad; Singh, S. K.

    2011-10-06

    We have studied the nuclear medium effects in the neutrino(antineutrino) induced interactions in nuclei which are relevant for present neutrino oscillation experiments in the few GeV energy region. The study is specially focused on calculating the cross sections and the event rates for atmospheric and accelerator neutrino experiments. The nuclear effects are found to be important for the quasielastic lepton production and the charged current incoherent and coherent pion production processes.

  16. Ambipolar phosphorene field effect transistor.

    PubMed

    Das, Saptarshi; Demarteau, Marcel; Roelofs, Andreas

    2014-11-25

    In this article, we demonstrate enhanced electron and hole transport in few-layer phosphorene field effect transistors (FETs) using titanium as the source/drain contact electrode and 20 nm SiO2 as the back gate dielectric. The field effect mobility values were extracted to be ∼38 cm(2)/Vs for electrons and ∼172 cm(2)/Vs for the holes. On the basis of our experimental data, we also comprehensively discuss how the contact resistances arising due to the Schottky barriers at the source and the drain end effect the different regime of the device characteristics and ultimately limit the ON state performance. We also propose and implement a novel technique for extracting the transport gap as well as the Schottky barrier height at the metal-phosphorene contact interface from the ambipolar transfer characteristics of the phosphorene FETs. This robust technique is applicable to any ultrathin body semiconductor which demonstrates symmetric ambipolar conduction. Finally, we demonstrate a high gain, high noise margin, chemical doping free, and fully complementary logic inverter based on ambipolar phosphorene FETs. PMID:25329532

  17. Nuclear-Electronic Coherence in Strong-Field Dissociative Ionization

    NASA Astrophysics Data System (ADS)

    Yu, Youliang; Wang, Yujun; Zeng, Shuo; Esry, B. D.

    2015-05-01

    In strong-field dissociative ionization of molecules, the ionization step is usually modeled since direct calculation is very challenging. In most of the models used to date, ionization is assumed to occur at several well-defined times accompanied by promotion of a nuclear wave packet to the ionic Born-Oppenheimer potential. Whether these nuclear wave packets should add coherently or incoherently in general is an open question. To answer it, we solve the time-dependent Schrödinger equation for one-dimensional H2+,where ionization is included naturally, and compare the observables, such as the kinetic energy release spectrum, with those from an ionization model. We then examine the validity of such models in strong-field dissociative ionization of H2+with reduced dimensionality. We do not, however, expect this physics to depend sensitively on the dimensionality. Supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

  18. Global climatic effects of a nuclear war: An interdisciplinary problem

    SciTech Connect

    Ghan, S.J.

    1988-05-01

    In summary, an elucidation of the global-scale response to a nuclear war is a problem of great breadth, involving many of the sub-disciplines of aerosol physics, meteorology, oceanography, atmospheric chemistry and ecology. As diverse as these fields are, communication between the sub-disciplines has been remarkably effective, with two major interdisciplinary reports published in the last few years. It is my belief that, in addition to addressing the global-scale implications of a nuclear war, the global effects effort also serves as an excellent example of an interdisciplinary research program. 23 refs.

  19. Solid Tumor-Targeting Theranostic Polymer Nanoparticle in Nuclear Medicinal Fields

    PubMed Central

    Makino, Akira; Kimura, Shunsaku

    2014-01-01

    Polymer nanoparticles can be prepared by self-assembling of amphiphilic polymers, and various types of molecular assemblies have been reported. In particular, in medicinal fields, utilization of these polymer nanoparticles as carriers for drug delivery system (DDS) has been actively tried, and some nanoparticulate drugs are currently under preclinical evaluations. A radionuclide is an unstable nucleus and decays with emission of radioactive rays, which can be utilized as a tracer in the diagnostic imaging systems of PET and SPECT and also in therapeutic purposes. Since polymer nanoparticles can encapsulate most of diagnostic and therapeutic agents with a proper design of amphiphilic polymers, they should be effective DDS carriers of radionuclides in the nuclear medicinal field. Indeed, nanoparticles have been recently attracting much attention as common platform carriers for diagnostic and therapeutic drugs and contribute to the development of nanotheranostics. In this paper, recent developments of solid tumor-targeting polymer nanoparticles in nuclear medicinal fields are reviewed. PMID:25379530

  20. Solid tumor-targeting theranostic polymer nanoparticle in nuclear medicinal fields.

    PubMed

    Makino, Akira; Kimura, Shunsaku

    2014-01-01

    Polymer nanoparticles can be prepared by self-assembling of amphiphilic polymers, and various types of molecular assemblies have been reported. In particular, in medicinal fields, utilization of these polymer nanoparticles as carriers for drug delivery system (DDS) has been actively tried, and some nanoparticulate drugs are currently under preclinical evaluations. A radionuclide is an unstable nucleus and decays with emission of radioactive rays, which can be utilized as a tracer in the diagnostic imaging systems of PET and SPECT and also in therapeutic purposes. Since polymer nanoparticles can encapsulate most of diagnostic and therapeutic agents with a proper design of amphiphilic polymers, they should be effective DDS carriers of radionuclides in the nuclear medicinal field. Indeed, nanoparticles have been recently attracting much attention as common platform carriers for diagnostic and therapeutic drugs and contribute to the development of nanotheranostics. In this paper, recent developments of solid tumor-targeting polymer nanoparticles in nuclear medicinal fields are reviewed. PMID:25379530

  1. Rotating-frame gradient fields for magnetic resonance imaging and nuclear magnetic resonance in low fields

    DOEpatents

    Bouchard, Louis-Serge; Pines, Alexander; Demas, Vasiliki

    2014-01-21

    A system and method for Fourier encoding a nuclear magnetic resonance (NMR) signal is disclosed. A static magnetic field B.sub.0 is provided along a first direction. An NMR signal from the sample is Fourier encoded by applying a rotating-frame gradient field B.sub.G superimposed on the B.sub.0, where the B.sub.G comprises a vector component rotating in a plane perpendicular to the first direction at an angular frequency .omega.in a laboratory frame. The Fourier-encoded NMR signal is detected.

  2. Relativistic mean-field hadronic models under nuclear matter constraints

    NASA Astrophysics Data System (ADS)

    Dutra, M.; Lourenço, O.; Avancini, S. S.; Carlson, B. V.; Delfino, A.; Menezes, D. P.; Providência, C.; Typel, S.; Stone, J. R.

    2014-11-01

    Background: The microscopic composition and properties of infinite hadronic matter at a wide range of densities and temperatures have been subjects of intense investigation for decades. The equation of state (EoS) relating pressure, energy density, and temperature at a given particle number density is essential for modeling compact astrophysical objects such as neutron stars, core-collapse supernovae, and related phenomena, including the creation of chemical elements in the universe. The EoS depends not only on the particles present in the matter, but, more importantly, also on the forces acting among them. Because a realistic and quantitative description of infinite hadronic matter and nuclei from first principles in not available at present, a large variety of phenomenological models has been developed in the past several decades, but the scarcity of experimental and observational data does not allow a unique determination of the adjustable parameters. Purpose: It is essential for further development of the field to determine the most realistic parameter sets and to use them consistently. Recently, a set of constraints on properties of nuclear matter was formed and the performance of 240 nonrelativistic Skyrme parametrizations was assessed [M. Dutra et al., Phys. Rev. C 85, 035201 (2012), 10.1103/PhysRevC.85.035201] in describing nuclear matter up to about three times nuclear saturation density. In the present work we examine 263 relativistic-mean-field (RMF) models in a comparable approach. These models have been widely used because of several important aspects not always present in nonrelativistic models, such as intrinsic Lorentz covariance, automatic inclusion of spin, appropriate saturation mechanism for nuclear matter, causality, and, therefore, no problems related to superluminal speed of sound in medium. Method: Three different sets of constraints related to symmetric nuclear matter, pure neutron matter, symmetry energy, and its derivatives were used. The

  3. Coherent nuclear resonant scattering by {sup 61}Ni using the nuclear lighthouse effect

    SciTech Connect

    Roth, T.; Leupold, O.; Wille, H.-C.; Rueffer, R.; Quast, K.W.; Burkel, E.; Roehlsberger, R.

    2005-04-01

    We have observed coherent nuclear resonant scattering of synchrotron radiation from the 67.41-keV level of {sup 61}Ni. The time evolution of the forward scattering signal was recorded by employing the nuclear lighthouse effect. This method is used to investigate Moessbauer isotopes in a coherent scattering process with synchrotron radiation at high transition energies. The decay of the excited ensemble of nuclei in Ni metal shows quantum beats that allowed the determination of the magnetic hyperfine field at the {sup 61}Ni nucleus. Moreover, we determined the lifetime of the 67.41-keV level of {sup 61}Ni to be 7.4(1) ns.

  4. Effective field theory out of equilibrium: Brownian quantum fields

    NASA Astrophysics Data System (ADS)

    Boyanovsky, D.

    2015-06-01

    The emergence of an effective field theory out of equilibrium is studied in the case in which a light field—the system—interacts with very heavy fields in a finite temperature bath. We obtain the reduced density matrix for the light field, its time evolution is determined by an effective action that includes the influence action from correlations of the heavy degrees of freedom. The non-equilibrium effective field theory yields a Langevin equation of motion for the light field in terms of dissipative and noise kernels that obey a generalized fluctuation dissipation relation. These are completely determined by the spectral density of the bath which is analyzed in detail for several cases. At T = 0 we elucidate the effect of thresholds in the renormalization aspects and the asymptotic emergence of a local effective field theory with unitary time evolution. At T\

  5. [Health effects of electromagnetic fields].

    PubMed

    Röösli, Martin

    2013-12-01

    Use of electricity causes extremely low frequency magnetic fields (ELF-MF) and wireless communication devices emit radiofrequency electromagnetic fields (RF-EMF). Average ELF-MF exposure is mainly determined by high voltage power lines and transformers at home or at the workplace, whereas RF-EMF exposure is mainly caused by devices operating close to the body (mainly mobile and cordless phones). Health effects of EMF are controversially discussed. The IARC classified ELF-MF and RF-EMF as possible carcinogenic. Most consistent epidemiological evidence was found for an association between ELF-MF and childhood leukaemia. If causal, 1 - 4 percent of all childhood leukaemia cases could be attributed to ELF-MF. Epidemiological research provided some indications for an association between ELF-MF and Alzheimer's diseases as well as amyotrophic lateral sclerosis, although not entirely consistent. Regarding mobile phones and brain tumours, some studies observed an increased risk after heavy or long term use on the one hand. On the other hand, brain tumour incidence was not found to have increased in the last decade in Sweden, England or the US. Acute effects of RF-EMF on non-specific symptoms of ill health seem unlikely according to randomized and double blind provocation studies. However, epidemiological research on long term effects is still limited. Although from the current state of the scientific knowledge a large individual health risk from RF-EMF exposure is unlikely, even a small risk would have substantial public health relevance because of the widespread use of wireless communication technologies. PMID:24297859

  6. Application of Phase-field Method in Predicting Gas Bubble Microstructure Evolution in Nuclear Fuels

    SciTech Connect

    Hu, Shenyang Y.; Li, Yulan; Sun, Xin; Gao, Fei; Devanathan, Ramaswami; Henager, Charles H.; Khaleel, Mohammad A.

    2010-04-30

    Fission product accumulation and gas bubble microstructure evolution in nuclear fuels strongly affect thermo-mechanical properties such as thermal conductivity, gas release, volumetric swelling and cracking, and hence the fuel performance. In this paper, a general phase-field model is developed to predict gas bubble formation and evolution. Important materials processes and thermodynamic properties including the generation of gas atoms and vacancies, sinks for vacancies and gas atoms, the elastic interaction among defects, gas re-solution, and inhomogeneity of elasticity and diffusivity are accounted for in the model. The simulations demonstrate the potential application of the phase-field method in investigating 1) heterogeneous nucleation of gas bubbles at defects; 2) effect of elastic interaction, inhomogeneity of material properties, and gas re-solution on gas bubble microstructures; and 3) effective properties from the output of phase-field simulations such as distribution of defects, gas bubbles, and stress fields.

  7. A Lagrangian effective field theory

    SciTech Connect

    Vlah, Zvonimir; White, Martin; Aviles, Alejandro

    2015-09-02

    We have continued the development of Lagrangian, cosmological perturbation theory for the low-order correlators of the matter density field. We provide a new route to understanding how the effective field theory (EFT) of large-scale structure can be formulated in the Lagrandian framework and a new resummation scheme, comparing our results to earlier work and to a series of high-resolution N-body simulations in both Fourier and configuration space. The `new' terms arising from EFT serve to tame the dependence of perturbation theory on small-scale physics and improve agreement with simulations (though with an additional free parameter). We find that all of our models fare well on scales larger than about two to three times the non-linear scale, but fail as the non-linear scale is approached. This is slightly less reach than has been seen previously. At low redshift the Lagrangian model fares as well as EFT in its Eulerian formulation, but at higher z the Eulerian EFT fits the data to smaller scales than resummed, Lagrangian EFT. Furthermore, all the perturbative models fare better than linear theory.

  8. A Lagrangian effective field theory

    DOE PAGESBeta

    Vlah, Zvonimir; White, Martin; Aviles, Alejandro

    2015-09-02

    We have continued the development of Lagrangian, cosmological perturbation theory for the low-order correlators of the matter density field. We provide a new route to understanding how the effective field theory (EFT) of large-scale structure can be formulated in the Lagrandian framework and a new resummation scheme, comparing our results to earlier work and to a series of high-resolution N-body simulations in both Fourier and configuration space. The `new' terms arising from EFT serve to tame the dependence of perturbation theory on small-scale physics and improve agreement with simulations (though with an additional free parameter). We find that all ofmore » our models fare well on scales larger than about two to three times the non-linear scale, but fail as the non-linear scale is approached. This is slightly less reach than has been seen previously. At low redshift the Lagrangian model fares as well as EFT in its Eulerian formulation, but at higher z the Eulerian EFT fits the data to smaller scales than resummed, Lagrangian EFT. Furthermore, all the perturbative models fare better than linear theory.« less

  9. Hanle effect in (In,Ga)As quantum dots: Role of nuclear spin fluctuations

    NASA Astrophysics Data System (ADS)

    Kuznetsova, M. S.; Flisinski, K.; Gerlovin, I. Ya.; Ignatiev, I. V.; Kavokin, K. V.; Verbin, S. Yu.; Yakovlev, D. R.; Reuter, D.; Wieck, A. D.; Bayer, M.

    2013-06-01

    The role of nuclear spin fluctuations in the dynamic polarization of nuclear spins by electrons is investigated in (In,Ga)As/GaAs quantum dots. The photoluminescence polarization under circularly polarized optical pumping in transverse magnetic fields (Hanle effect) is studied. A weak additional magnetic field parallel to the optical axis is used to control the efficiency of nuclear spin cooling and the sign of nuclear spin temperature. The shape of the Hanle curve is drastically modified when changing this control field, as observed earlier in bulk semiconductors and quantum wells. However, the standard nuclear spin cooling theory, operating with the mean nuclear magnetic field (Overhauser field), fails to describe the experimental Hanle curves in a certain range of control fields. This controversy is resolved by taking into account the nuclear spin fluctuations owed to the finite number of nuclei in the quantum dot. We propose a model considering cooling of the nuclear spin system by electron spins experiencing fast vector precession in the random Overhauser fields of nuclear spin fluctuations. The model allows us to accurately describe the measured Hanle curves and to evaluate the parameters of the electron-nuclear spin system of the studied quantum dots.

  10. Deregulation and Nuclear Training: Cost Effective Alternatives

    SciTech Connect

    Richard P. Coe; Patricia A. Lake

    2000-11-12

    Training is crucial to the success of any organization. It is also expensive, with some estimates exceeding $50 billion annually spent on training by U.S. corporations. Nuclear training, like that of many other highly technical organizations, is both crucial and costly. It is unlikely that the amount of training can be significantly reduced. If anything, current trends indicate that training needs will probably increase as the industry and workforce ages and changes. With the advent of energy deregulation in the United States, greater pressures will surface to make the costs of energy more cost-competitive. This in turn will drive businesses to more closely examine existing costs and find ways to do things in a more cost-effective way. The commercial nuclear industry will be no exception, and nuclear training will be equally affected. It is time for nuclear training and indeed the entire nuclear industry to begin using more aggressive techniques to reduce costs. This includes the need for nuclear training to find alternatives to traditional methods for the delivery of cost-effective high-quality training that meets regulatory requirements and produces well-qualified personnel capable of working in an efficient and safe manner. Computer-based and/or Web-based training are leading emerging technologies.

  11. Effective field theory, past and future

    NASA Astrophysics Data System (ADS)

    Weinberg, Steven

    2016-02-01

    I reminisce about the early development of effective field theories of the strong interactions, comment briefly on some other applications of effective field theories, and then take up the idea that the Standard Model and General Relativity are the leading terms in an effective field theory. Finally, I cite recent calculations that suggest that the effective field theory of gravitation and matter is asymptotically safe.

  12. Nuclear force and the EMC effect

    NASA Astrophysics Data System (ADS)

    Wang, Rong; Chen, Xurong

    2015-04-01

    A linear correlation is shown quantitatively between the magnitude of the EMC effect measured in electron deep inelastic scattering (DIS) and the nuclear residual strong interaction energy (RSIE) obtained from nuclear binding energy subtracting the Coulomb energy contribution. This phenomenological relationship is used to extract the size of in-medium correction (IMC) effect on deuteron and to predict the EMC slopes | dREMC / dx | of various nuclei. We further investigate the correlations between RSIE and other quantities which are related to the EMC effect. The observed correlations among RSIE, EMC slope and SRC ratio R2NNtotal /Nnp(S31) imply that the local nuclear environment drives the modification of quark distributions.

  13. Stray-field nuclear magnetic resonance imaging in microgravity conditions

    NASA Astrophysics Data System (ADS)

    Garrido, Leoncio; Sampayo, José

    2008-03-01

    Magnetic levitation has been proposed as an alternative approach to simulate on Earth microgravity conditions encountered in space, allowing the investigation of weightlessness on materials and biological systems. In general, very strong magnetic fields, 15T or higher, are required to achieve levitation for a majority of diamagnetic substances. Here, we show that it is possible to achieve levitation of these substances in a commercial superconductive magnet operating with a nuclear magnetic resonance (NMR) spectrometer at 9.4T at ambient conditions. Furthermore, stray-field proton NMR imaging is performed in situ at the location where a sample is levitating, showing that it is feasible to obtain the corresponding one-dimensional profile. Considering that water is a diamagnetic substance and the main constituent of living systems, the outlined approach could be useful to investigate alterations in water proton NMR properties induced by low gravity and magnetic forces upon levitating, e.g., seeds, cells, etc. In addition to protons, it would also be possible to observe other nuclei (e.g., F19, P31, etc.) that may be of interest in metabolic and therapeutic investigations.

  14. Electric field effects on nuclear magnetic shielding of the 1:1 and 2:1 (homo and heterochiral) complexes of XOOX' (X, X' = H, CH3) with lithium cation and their chiral discrimination

    NASA Astrophysics Data System (ADS)

    Alkorta, Ibon; Elguero, José; Provasi, Patricio F.; Pagola, Gabriel I.; Ferraro, Marta B.

    2011-09-01

    The set of 1:1 and 2:1 complexes of XOOX' (X, X' = H, CH3) with lithium cation has been studied to determine if they are suitable candidates for chiral discrimination in an isotropic medium via nuclear magnetic resonance spectroscopy. Conventional nuclear magnetic resonance is unable to distinguish between enantiomers in the absence of a chiral solvent. The criterion for experimental detection is valuated by the isotropic part of nuclear shielding polarisability tensors, related to a pseudoscalar of opposite sign for two enantiomers. The study includes calculations at coupled Hartree-Fock and density functional theory schemes for 17O nucleus in each compound. Additional calculations for 1H are also included for some compounds. A huge static homogeneous electric field, perpendicular to the magnetic field of the spectromer, as big as ≈1.7 × 108 V m-1 should be applied to observe a shift of ≈1 ppm for 17O magnetic shielding in the proposed set of complexes.

  15. Electric field effects on nuclear magnetic shielding of the 1:1 and 2:1 (homo and heterochiral) complexes of XOOX' (X, X' = H, CH3) with lithium cation and their chiral discrimination.

    PubMed

    Alkorta, Ibon; Elguero, José; Provasi, Patricio F; Pagola, Gabriel I; Ferraro, Marta B

    2011-09-14

    The set of 1:1 and 2:1 complexes of XOOX' (X, X' = H, CH(3)) with lithium cation has been studied to determine if they are suitable candidates for chiral discrimination in an isotropic medium via nuclear magnetic resonance spectroscopy. Conventional nuclear magnetic resonance is unable to distinguish between enantiomers in the absence of a chiral solvent. The criterion for experimental detection is valuated by the isotropic part of nuclear shielding polarisability tensors, related to a pseudoscalar of opposite sign for two enantiomers. The study includes calculations at coupled Hartree-Fock and density functional theory schemes for (17)O nucleus in each compound. Additional calculations for (1)H are also included for some compounds. A huge static homogeneous electric field, perpendicular to the magnetic field of the spectromer, as big as ≈1.7 × 10(8) V m(-1) should be applied to observe a shift of ≈1 ppm for (17)O magnetic shielding in the proposed set of complexes. PMID:21932885

  16. Evaluation of Near Field Atmospheric Dispersion Around Nuclear Facilities Using a Lorentzian Distribution Methodology

    SciTech Connect

    Hawkley, Gavin

    2014-01-01

    Atmospheric dispersion modeling within the near field of a nuclear facility typically applies a building wake correction to the Gaussian plume model, whereby a point source is modeled as a plane source. The plane source results in greater near field dilution and reduces the far field effluent concentration. However, the correction does not account for the concentration profile within the near field. Receptors of interest, such as the maximally exposed individual, may exist within the near field and thus the realm of building wake effects. Furthermore, release parameters and displacement characteristics may be unknown, particularly during upset conditions. Therefore, emphasis is placed upon the need to analyze and estimate an enveloping concentration profile within the near field of a release. This investigation included the analysis of 64 air samples collected over 128 wk. Variables of importance were then derived from the measurement data, and a methodology was developed that allowed for the estimation of Lorentzian-based dispersion coefficients along the lateral axis of the near field recirculation cavity; the development of recirculation cavity boundaries; and conservative evaluation of the associated concentration profile. The results evaluated the effectiveness of the Lorentzian distribution methodology for estimating near field releases and emphasized the need to place air-monitoring stations appropriately for complete concentration characterization. Additionally, the importance of the sampling period and operational conditions were discussed to balance operational feedback and the reporting of public dose.

  17. The climatic effects of nuclear war

    NASA Technical Reports Server (NTRS)

    Turco, R. P.; Toon, O. B.; Ackerman, T. P.; Pollack, J. B.; Sagan, C.

    1984-01-01

    The effects of various US-USSR nuclear-exchange scenarios on global climate are investigated by means of computer simulations, summarizing the results of Turco et al. (1983) and follow-up studies using 3D global-circulation models. A nuclear-scenario model is used to determine the amounts of dust, smoke, radioactivity, and pyrotoxins generated by a particular type of nuclear exchange (such as a general 5,000-Mt exchange, a 1,000-Mt limited exchange, a 5,000-Mt hard-target counterforce attack, and a 100-Mt attack on cities only): a particle-microphysics model predicts the evolution of the dust and smoke particles; and a radiative-convective climate model estimates the effects of the dust and smoke clouds on the global radiation budget. The findings are presented in graphs, diagrams, and a table. Thick clouds blocking most sunlight over the Northern Hemisphere midlatitudes for weeks or months and producing ground-temperature reductions of 20-40 C, disruption of global circulation patterns, and rapid spread of clouds to the Southern Hemisphere are among the 'nuclear-winter' effects predicted for the 5,000-Mt baseline case. The catastrophic consequences for plant, animal, and human populations are considered, and the revision of superpower nuclear strategies is urged.

  18. Coherent transfer of nuclear spin polarization in field-cycling NMR experiments

    SciTech Connect

    Pravdivtsev, Andrey N.; Yurkovskaya, Alexandra V.; Ivanov, Konstantin L.; Vieth, Hans-Martin

    2013-12-28

    Coherent polarization transfer effects in a coupled spin network have been studied over a wide field range. The transfer mechanism is based on exciting zero-quantum coherences between the nuclear spin states by means of non-adiabatic field jump from high to low magnetic field. Subsequent evolution of these coherences enables conversion of spin order in the system, which is monitored after field jump back to high field. Such processes are most efficient when the spin system passes through an avoided level crossing during the field variation. The polarization transfer effects have been demonstrated for N-acetyl histidine, which has five scalar coupled protons; the initial spin order has been prepared by applying RF-pulses at high magnetic field. The observed oscillatory transfer kinetics is taken as a clear indication of a coherent mechanism; level crossing effects have also been demonstrated. The experimental data are in very good agreement with the theoretical model of coherent polarization transfer. The method suggested is also valid for other types of initial polarization in the spin system, most notably, for spin hyperpolarization.

  19. Nuclear relaxation in an electric field enables the determination of isotropic magnetic shielding

    NASA Astrophysics Data System (ADS)

    Garbacz, Piotr

    2016-08-01

    It is shown that in contrast to the case of nuclear relaxation in a magnetic field B, simultaneous application of the magnetic field B and an additional electric field E causes transverse relaxation of a spin-1/2 nucleus with the rate proportional to the square of the isotropic part of the magnetic shielding tensor. This effect can contribute noticeably to the transverse relaxation rate of heavy nuclei in molecules that possess permanent electric dipole moments. Relativistic quantum mechanical computations indicate that for 205Tl nucleus in a Pt-Tl bonded complex, Pt(CN)5Tl, the transverse relaxation rate induced by the electric field is of the order of 1 s-1 at E = 5 kV/mm and B = 10 T.

  20. Radiation Effects in Nuclear Waste Materials

    SciTech Connect

    Weber, William J.; Corrales, L. Rene; Ness, Nancy J.; Williford, Ralph E.; Heinisch, Howard L.; Thevuthasan, Suntharampillai; Icenhower, Jonathan P.; McGrail, B. Peter; Devanathan, Ramaswami; Van Ginhoven, Renee M.; Song, Jakyoung; Park, Byeongwon; Jiang, Weilin; Begg, Bruce D.; Birtcher, R. B.; Chen, X.; Conradson, Steven D.

    2000-10-02

    Radiation effects from the decay of radionuclides may impact the long-term performance and stability of nuclear waste forms and stabilized nuclear materials. In an effort to address these concerns, the objective of this project was the development of fundamental understanding of radiation effects in glasses and ceramics, particularly on solid-state radiation effects and their influence on aqueous dissolution kinetics. This study has employed experimental, theoretical and computer simulation methods to obtain new results and insights into radiation damage processes and to initiate the development of predictive models. Consequently, the research that has been performed under this project has significant implications for the High-Level Waste and Nuclear Materials focus areas within the current DOE/EM mission. In the High-Level Waste (HLW) focus area, the results of this research could lead to improvements in the understanding of radiation-induced degradation mechanisms and their effects on dissolution kinetics, as well as development of predictive models for waste form performance. In the Nuclear Materials focus area, the results of this research could lead to improvements in the understanding of radiation effects on the chemical and structural properties of materials for the stabilization and long-term storage of plutonium, highly-enriched uranium, and other actinides. Ultimately, this research could result in improved glass and ceramic materials for the stabilization and immobilization of high-level tank waste, plutonium residues and scraps, surplus weapons plutonium, highly-enriched uranium, other actinides, and other radioactive materials.

  1. High-Field Dynamic Nuclear Polarization for Solid and Solution Biological NMR

    PubMed Central

    Barnes, A.B.; Paëpe, G. De; van der Wel, P.C.A.; Hu, K.-N.; Joo, C.-G.; Bajaj, V.S.; Mak-Jurkauskas, M.L.; Sirigiri, J.R.; Herzfeld, J.; Temkin, R.J.; Griffin, R.G.

    2008-01-01

    Dynamic nuclear polarization (DNP) results in a substantial nuclear polarization enhancement through a transfer of the magnetization from electrons to nuclei. Recent years have seen considerable progress in the development of DNP experiments directed towards enhancing sensitivity in biological nuclear magnetic resonance (NMR). This review covers the applications, hardware, polarizing agents, and theoretical descriptions that were developed at the Francis Bitter Magnet Laboratory at Massachusetts Institute of Technology for high-field DNP experiments. In frozen dielectrics, the enhanced nuclear polarization developed in the vicinity of the polarizing agent can be efficiently dispersed to the bulk of the sample via 1H spin diffusion. This strategy has been proven effective in polarizing biologically interesting systems, such as nanocrystalline peptides and membrane proteins, without leading to paramagnetic broadening of the NMR signals. Gyrotrons have been used as a source of high-power (5–10 W) microwaves up to 460 GHz as required for the DNP experiments. Other hardware has also been developed allowing in situ microwave irradiation integrated with cryogenic magic-angle-spinning solid-state NMR. Advances in the quantum mechanical treatment are successful in describing the mechanism by which new biradical polarizing agents yield larger enhancements at higher magnetic fields. Finally, pulsed methods and solution experiments should play a prominent role in the future of DNP. PMID:19194532

  2. The effects of a nuclear war

    SciTech Connect

    Alred, W.T. )

    1990-10-01

    Many factors influence the impact that a nuclear war would have on both the environment and survivors. These factors include, although are not limited to, the type of nuclear weapons used, the amount of these weapons, and the time of year a war would take place. The effects that a major nuclear war would have on the environment would vary greatly depending on the factors previously mentioned. Some effects that would occur are: major climatic changes, destruction of most food crops, contamination of current food and water supplies, and the deaths of animals and insects that are crucial to the balance of the environment. The factors that influence the survivors also vary; however, certain problems have been predicted by researchers. Among these problems are psychological disorders, lack of food supplies, the elimination of medical relief, and exposure from both radiation and the changing environment. All these effects, as well as others, tend to give researchers a much different view of the effects that a nuclear war would have on the environment and survivors than has been predicted since before the mid nineteen-eighties.

  3. Surface effects of underground nuclear explosions

    SciTech Connect

    Allen, B.M.; Drellack, S.L. Jr.; Townsend, M.J.

    1997-06-01

    The effects of nuclear explosions have been observed and studied since the first nuclear test (code named Trinity) on July 16, 1945. Since that first detonation, 1,053 nuclear tests have been conducted by the US, most of which were sited underground at the Nevada Test Site (NTS). The effects of underground nuclear explosions (UNEs) on their surroundings have long been the object of much interest and study, especially for containment, engineering, and treaty verification purposes. One aspect of these explosion-induced phenomena is the disruption or alteration of the near-surface environment, also known as surface effects. This report was prepared at the request of the Los Alamos National Laboratory (LANL), to bring together, correlate, and preserve information and techniques used in the recognition and documentation of surface effects of UNEs. This report has several main sections, including pertinent background information (Section 2.0), descriptions of the different types of surface effects (Section 3.0), discussion of their application and limitations (Section 4.0), an extensive bibliography and glossary (Section 6.0 and Appendix A), and procedures used to document geologic surface effects at the NTS (Appendix C). Because a majority of US surface-effects experience is from the NTS, an overview of pertinent NTS-specific information also is provided in Appendix B. It is not within the scope of this report to explore new relationships among test parameters, physiographic setting, and the types or degree of manifestation of surface effects, but rather to compile, summarize, and capture surface-effects observations and interpretations, as well as documentation procedures and the rationale behind them.

  4. Effectively Managing Nuclear Risk Through Human Performance Improvement

    SciTech Connect

    Coe, Richard; Lake, Patricia

    2003-09-01

    The U.S. commercial nuclear industry has just completed an outstanding decade of plant performance. Safety levels and electric production are at unprecedented high levels and continue to exceed even high industry goals. Nuclear energy continues to keep the highest priority on performance improvement programs and highly trained and qualified people that maintain its record setting safety and reliability of operations. While the industry has maintained a high level of performance, the advent of deregulation and the consolidation of nuclear power plant ownership, as well as the current climate for concern about both rising energy costs and the availability of power, have raised the standard for nuclear energy's level of competitiveness in today's market place. The resulting challenge is how to more effectively manage risk and to improve performance even further in a generally high-performing industry. One of the most effective ways to develop this culture is to apply the principles of Hum an Performance Technology, or HPT. HPT is a relatively new field. Its principles are derived from the research and practice of behavioral and cognitive psychologists, instructional technologists, training designers, organizational developers, and various human resource specialists. Using the principles of HPT can help the nuclear industry successfully meet ever-changing environmental and business demands.

  5. Nuclear Effects in Hadron Production at HERMES

    SciTech Connect

    Bianchi, Nicola

    2007-11-19

    The influence of the nuclear medium on the lepto-production of hadrons was studied in semi-inclusive deep-inelastic scattering off several nuclear targets. In particular, at the HERMES experiment at DESY, the differential multiplicity for nuclei relative to that of deuterium has been measured for the first time for various identified hadrons ({pi}{sup +}, {pi}{sup -}, {pi}{sup 0}, K{sup +}, K{sup -}, p and anti-p) as a function of the virtual photon energy {nu}, the fraction z of this energy transferred to the hadron, and the hadron transverse momentum squared p{sub t}{sup 2}. The distribution of the hadron transverse momentum is broadened towards high p{sub t}{sup 2} in the nuclear medium, in a manner resembling the Cronin effect previously observed in collisions of heavy ions and protons with nuclei.

  6. Phase-field Modeling of Gas Bubbles and Thermal Conductivity Evolution in Nuclear Fuels

    SciTech Connect

    Hu, Shenyang Y.; Henager, Charles H.; Heinisch, Howard L.; Stan, Marius; Baskes, Michael I.; Valone, Steven

    2009-07-15

    The major factors that influence the thermal conductivity of the ceramics and metals are temperature, stoichiometry, microstructure, porosity, and point defects. Nuclear fuels and structure materials are subject to a severe radiation environment and their properties, including thermal conductivity change significantly with time and irradiation level. In particular, the accumulation of fission products and the formation of He bubbles can decrease the heat transfer, leading to overheating of the fuel element. In this work, we use the phase-field method to study the effect of microstructural changes on thermal conductivity. We developed a phase-field model to simulate the He bubble formation and growth in a single/polycrystalline material with defects. The model takes into account the generation of gas atoms and defects, gas atom diffusivity inhomogeneity, gas atom segregation, and gas bubble nucleation. With the model, we simulated the gas bubble and temperature evolution, and calculated the effect of gas bubble volume fraction on effective thermal conductivity.

  7. Climatic Effects of Regional Nuclear War

    NASA Technical Reports Server (NTRS)

    Oman, Luke D.

    2011-01-01

    We use a modern climate model and new estimates of smoke generated by fires in contemporary cities to calculate the response of the climate system to a regional nuclear war between emerging third world nuclear powers using 100 Hiroshima-size bombs (less than 0.03% of the explosive yield of the current global nuclear arsenal) on cities in the subtropics. We find significant cooling and reductions of precipitation lasting years, which would impact the global food supply. The climate changes are large and longlasting because the fuel loadings in modern cities are quite high and the subtropical solar insolation heats the resulting smoke cloud and lofts it into the high stratosphere, where removal mechanisms are slow. While the climate changes are less dramatic than found in previous "nuclear winter" simulations of a massive nuclear exchange between the superpowers, because less smoke is emitted, the changes seem to be more persistent because of improvements in representing aerosol processes and microphysical/dynamical interactions, including radiative heating effects, in newer global climate system models. The assumptions and calculations that go into these conclusions will be described.

  8. From effective field theories to effective density functionals in and beyond the mean field

    NASA Astrophysics Data System (ADS)

    Grasso, M.; Lacroix, D.; van Kolck, U.

    2016-06-01

    Since the 1975 Nobel Prize in Physics, nuclear theory has evolved along two main directions. On the one hand, the energy–density functional (EDF) theory was established, which presently encompasses (by enlarging the EDF framework) all the mean-field and beyond-mean-field theories based on energy functionals produced by effective phenomenological interactions. Highly sophisticated structure and reaction models are currently available for the treatment of medium-mass and heavy nuclei. On the other hand, effective field theories (EFTs) have rendered possible the formulation of QCD as a low-energy hadronic theory. Ab initio methods have recently achieved remarkable success in the application of EFT or EFT-inspired potentials to structure analyses of light nuclei. Different but complementary competences have been developed during the past few decades in the EDF and EFT communities. Bridges and connections have in some cases been identified and constructed. We review here some of the developments that have been performed within the EDF theory and the EFT during recent years, with some emphasis on analogies and connections that may one day provide a unified picture of the two theories. Illustrations are given for infinite matter and finite nuclei.

  9. Global nuclear structure effects of the tensor interaction

    SciTech Connect

    Zalewski, M.; Olbratowski, P.; Rafalski, M.; Werner, T. R.; Satula, W.; Wyss, R. A.

    2009-12-15

    A direct fit of the isoscalar spin-orbit (SO) and both isoscalar and isovector tensor coupling constants to the f{sub 5/2}-f{sub 7/2} SO splittings in {sup 40}Ca, {sup 56}Ni, and {sup 48}Ca nuclei requires a drastic reduction of the isoscalar SO strength and strong attractive tensor coupling constants. The aim of this work is to address further consequences of these strong attractive tensor and weak SO fields on binding energies, nuclear deformability, and high-spin states. In particular, the contribution to the nuclear binding energy from the tensor field shows a generic magic structure with tensorial magic numbers N(Z)=14,32,56, or 90, corresponding to the maximum spin asymmetries in 1d{sub 5/2}, 1f{sub 7/2}+2p{sub 3/2}, 1g{sub 9/2}+2d{sub 5/2}, and 1h{sub 11/2}+2f{sub 7/2} single-particle configurations, respectively, and that these numbers are smeared out by pairing correlations and deformation effects. The consequences of strong attractive tensor fields and weak SO interaction for nuclear stability at the drip lines are also examined, particularly those close to the tensorial doubly magic nuclei. The possibility of an entirely new tensor-force-driven deformation effect is discussed.

  10. Effects of δ mesons in relativistic mean field theory

    NASA Astrophysics Data System (ADS)

    Singh, Shailesh K.; Biswal, S. K.; Bhuyan, M.; Patra, S. K.

    2014-04-01

    The effect of δ- and ω-ρ-meson cross couplings on asymmetry nuclear systems are analyzed in the framework of an effective field theory motivated relativistic mean field formalism. The calculations are done on top of the G2 parameter set, where these contributions are absent. To show the effect of δ meson on the nuclear system, we split the isospin coupling into two parts: (i) gρ due to ρ meson and (ii) gδ for δ meson. Thus, our investigation is based on varying the coupling strengths of the δ and ρ mesons to reproduce the binding energies of the nuclei Ca48 and Pb208. We calculate the root mean square radius, binding energy, single particle energy, density, and spin-orbit interaction potential for some selected nuclei and evaluate the Lsym and Esym coefficients for nuclear matter as function of δ- and ω-ρ-meson coupling strengths. As expected, the influence of these effects are negligible for the symmetric nuclear system, but substantial for the contribution with large isospin asymmetry.

  11. Adolescents' Knowledge of Nuclear Issues and the Effects of Nuclear War.

    ERIC Educational Resources Information Center

    Roscoe, Bruce; Goodwin, Megan P.

    1987-01-01

    Surveyed 357 college students to assess awareness of the status of nuclear arms development and possible effects of nuclear war on people and environment. Results suggest that older adolescents are extremely uninformed regarding the current status of nuclear issues and consequences of nuclear war. Indicates a strong need to educate young people…

  12. Uncertainty quantification of effective nuclear interactions

    NASA Astrophysics Data System (ADS)

    Pérez, R. Navarro; Amaro, J. E.; Arriola, E. Ruiz

    2016-03-01

    We give a brief review on the development of phenomenological NN interactions and the corresponding quantification of statistical uncertainties. We look into the uncertainty of effective interactions broadly used in mean field calculations through the Skyrme parameters and effective field theory counterterms by estimating both statistical and systematic uncertainties stemming from the NN interaction. We also comment on the role played by different fitting strategies on the light of recent developments.

  13. Measurement of the true transverse nuclear magnetic resonance relaxation in the presence of field gradients

    NASA Astrophysics Data System (ADS)

    Mitchell, J.; Chandrasekera, T. C.; Gladden, L. F.

    2013-08-01

    A measure of the nuclear spin transverse relaxation time T2, as determined using the nuclear magnetic resonance Carr-Purcell Meiboom-Gill (CPMG) experiment, provides unique information characterizing the microstructure of porous media which are themselves ubiquitous across fields of petrophysics, biophysics, and chemical engineering. However, the CPMG measurement is sensitive to diffusion in large magnetic field gradients. Under such conditions an effective relaxation time T_{2,eff} is observed instead, described by a combination of relaxation and diffusion exponents. The relaxation exponent always varies as nte (where n is the number, and te is the temporal separation, of spin echoes). The diffusion exponent varies as nt_e^k, where 1 < k ⩽ 3, although the exact analytic form is often unknown. Here we present a general approach to separating the influence of relaxation and diffusion by utilizing a composite diffusion exponent. Any T_{2,eff} component with a power of k > 1 is removed to provide a measure of the true T2 relaxation time distribution from CPMG data acquired in the presence of a strong background gradient. We apply the technique to discriminate between the effects of relaxation and diffusion in porous media using catalysts and rocks as examples. The method is generally applicable to any CPMG measurements conducted in the presence of a static magnetic field gradient.

  14. Electric Field Effect in Intrinsic Josephson Junctions

    NASA Astrophysics Data System (ADS)

    Koyama, T.

    The electric field effect in intrinsic Josephson junction stacks (IJJ's) is investigated on the basis of the capacitively-coupled IJJ model. We clarify the current-voltage characteristics of the IJJ's in the presence of an external electric field. It is predicted that the IJJ's show a dynamical transition to the voltage state as the external electric field is increased.

  15. Nuclear quantum effects and kinetic isotope effects in enzyme reactions.

    PubMed

    Vardi-Kilshtain, Alexandra; Nitoker, Neta; Major, Dan Thomas

    2015-09-15

    Enzymes are extraordinarily effective catalysts evolved to perform well-defined and highly specific chemical transformations. Studying the nature of rate enhancements and the mechanistic strategies in enzymes is very important, both from a basic scientific point of view, as well as in order to improve rational design of biomimetics. Kinetic isotope effect (KIE) is a very important tool in the study of chemical reactions and has been used extensively in the field of enzymology. Theoretically, the prediction of KIEs in condensed phase environments such as enzymes is challenging due to the need to include nuclear quantum effects (NQEs). Herein we describe recent progress in our group in the development of multi-scale simulation methods for the calculation of NQEs and accurate computation of KIEs. We also describe their application to several enzyme systems. In particular we describe the use of combined quantum mechanics/molecular mechanics (QM/MM) methods in classical and quantum simulations. The development of various novel path-integral methods is reviewed. These methods are tailor suited to enzyme systems, where only a few degrees of freedom involved in the chemistry need to be quantized. The application of the hybrid QM/MM quantum-classical simulation approach to three case studies is presented. The first case involves the proton transfer in alanine racemase. The second case presented involves orotidine 5'-monophosphate decarboxylase where multidimensional free energy simulations together with kinetic isotope effects are combined in the study of the reaction mechanism. Finally, we discuss the proton transfer in nitroalkane oxidase, where the enzyme employs tunneling as a catalytic fine-tuning tool. PMID:25769515

  16. Quadrupolar effects on nuclear spins of neutral arsenic donors in silicon

    NASA Astrophysics Data System (ADS)

    Franke, David P.; Pflüger, Moritz P. D.; Mortemousque, Pierre-André; Itoh, Kohei M.; Brandt, Martin S.

    2016-04-01

    We present electrically detected electron nuclear double resonance measurements of the nuclear spins of ionized and neutral arsenic donors in strained silicon. In addition to a reduction of the hyperfine coupling, we find significant quadrupole interactions of the nuclear spin of the neutral donors of the order of 10 kHz. By comparing these to the quadrupole shifts due to crystal fields measured for the ionized donors, we identify the effect of the additional electron on the electric field gradient at the nucleus. This extra component is expected to be caused by the coupling to electric field gradients created due to changes in the electron wave function under strain.

  17. Nuclear matter properties in the relativistic mean-field theory at finite temperature with interaction between sigma-omega mesons

    SciTech Connect

    Costa, R. S.; Duarte, S. B.; Oliveira, J. C. T.; Chiapparini, M.

    2010-05-21

    We study the nuclear matter properties in the regime of high temperatures using a relativistic mean-field theory. Contrasting with the usual linear Walecka model, we include the sigma-omega meson coupling in order to investigate the role of this interaction in the nucleon effective mass behavior. Some numerical results are presented and discussed.

  18. Magnetic field effect on charged Brownian swimmers

    NASA Astrophysics Data System (ADS)

    Sandoval, M.; Velasco, R. M.; Jiménez-Aquino, J. I.

    2016-01-01

    We calculate the effective diffusion of a spherical self-propelled charged particle swimming at low Reynolds number, and subject to a time-dependent magnetic field and thermal agitation. We find that the presence of an external magnetic field may reduce or enhance (depending on the type of swimming and magnetic field applied) the swimmer's effective diffusion, hence we get another possible strategy to control its displacement. For swimmers performing reciprocal motion, and under an oscillating time-dependent magnetic field, mechanical resonance appears when the swimmer and magnetic frequencies coincide, thus enhancing the particle's effective diffusion. Our analytical results are compared with Brownian Dynamics simulations and we obtain excellent agreement.

  19. Nuclear Spin Maser at Highly Stabilized Low Magnetic Field and Search for Atomic EDM

    SciTech Connect

    Yoshimi, A.; Asahi, K.; Inoue, T.; Uchida, M.; Hatakeyama, N.; Tsuchiya, M.; Kagami, S.

    2009-08-04

    A nuclear spin maser is operated at a low static field through an active feedback scheme based on an optical nuclear spin detection and succeeding spin control by a transverse field application. The frequency stability of this optical-coupling spin maser is improved by installation of a low-noise current source for a solenoid magnet producing a static magnetic field in the maser operation. Experimental devices for application of the maser to EDM experiment are being developed.

  20. Novel 1H low field nuclear magnetic resonance applications for the field of biodiesel

    PubMed Central

    2013-01-01

    Background Biodiesel production has increased dramatically over the last decade, raising the need for new rapid and non-destructive analytical tools and technologies. 1H Low Field Nuclear Magnetic Resonance (LF-NMR) applications, which offer great potential to the field of biodiesel, have been developed by the Phyto Lipid Biotechnology Lab research team in the last few years. Results Supervised and un-supervised chemometric tools are suggested for screening new alternative biodiesel feedstocks according to oil content and viscosity. The tools allowed assignment into viscosity groups of biodiesel-petrodiesel samples whose viscosity is unknown, and uncovered biodiesel samples that have residues of unreacted acylglycerol and/or methanol, and poorly separated and cleaned glycerol and water. In the case of composite materials, relaxation time distribution, and cross-correlation methods were successfully applied to differentiate components. Continuous distributed methods were also applied to calculate the yield of the transesterification reaction, and thus monitor the progress of the common and in-situ transesterification reactions, offering a tool for optimization of reaction parameters. Conclusions Comprehensive applied tools are detailed for the characterization of new alternative biodiesel resources in their whole conformation, monitoring of the biodiesel transesterification reaction, and quality evaluation of the final product, using a non-invasive and non-destructive technology that is new to the biodiesel research area. A new integrated computational-experimental approach for analysis of 1H LF-NMR relaxometry data is also presented, suggesting improved solution stability and peak resolution. PMID:23590829

  1. Nuclear Magnetic Double Resonance Using Weak Perturbing RF Fields

    ERIC Educational Resources Information Center

    Reynolds, G. Fredric

    1977-01-01

    Describes a nuclear magnetic resonance experimental example of spin tickling; also discusses a direct approach for verifying the relative signs of coupling constants in three-spin cyclopropyl systems. (SL)

  2. Topical Developments in High-Field Dynamic Nuclear Polarization

    PubMed Central

    Kiesewetter, Matthew K.; Frantz, Derik K.; Walish, Joseph J.; Ravera, Enrico; Luchinat, Claudio; Swager, Timothy M.; Griffin, Robert G.

    2015-01-01

    We report our recent efforts directed at improving high-field DNP experiments. We investigated a series of thiourea nitroxide radicals and the associated DNP enhancements ranging from ε = 25 to 82 that demonstrate the impact of molecular structure on performance. We directly polarized low-gamma nuclei including 13C, 2H, and 17O using trityl via the cross effect. We discuss a variety of sample preparation techniques for DNP with emphasis on the benefit of methods that do not use a glass-forming cryoprotecting matrix. Lastly, we describe a corrugated waveguide for use in a 700 MHz / 460 GHz DNP system that improves microwave delivery and increases enhancements up to 50%. PMID:25977588

  3. Counterintuitive energy shifts in joint electron-nuclear-energy spectra of strong-field fragmentation of H2+

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Li, Min; Zhou, Yueming; Li, Yang; Lan, Pengfei; Lu, Peixiang

    2016-01-01

    By numerically solving the time-dependent Schrödinger equation, we investigate electron-nuclear-energy sharing in strong-field fragmentation of the H2+ molecule. We find a counterintuitive energy shift in the joint electron-nuclear-energy spectrum. This energy shift becomes larger for lower nuclear energies. Through tracing the time evolution of the electron wave packet of bound states, we identify that the energy shift originates from the Stark effect due to the coupling of the ground state and the first exited state of the H2+ molecule in strong laser fields. We achieve a good agreement between the ab initio result and the analytic method that includes the Stark effect of molecules.

  4. Field-induced spin reorientation in [Fe/Cr ] n multilayers studied by nuclear resonance reflectivity

    NASA Astrophysics Data System (ADS)

    Andreeva, M.; Gupta, A.; Sharma, G.; Kamali, S.; Okada, K.; Yoda, Y.

    2015-10-01

    We present depth-resolved nuclear resonance reflectivity studies of the magnetization evolution in [57Fe(3nm ) /Cr (1.2 nm ) ] 10 multilayer under applied external field. The measurements have been performed at the station BL09XU of SPring-8 at different values of the external field (0-1500 Oe). We apply the joint fit of the delayed reflectivity curves and the time spectra of the nuclear resonance reflectivity measured at different grazing angles for enhancement of the depth resolution and reliability of results. We show that the azimuth angle, which is used in all papers devoted to the magnetization profile determination, has a more complicated physical sense due to the partially coherent averaging of the scattering amplitudes from magnetic lateral domains. We describe how to select the true azimuth angle from the determined "effective azimuth angle." Finally we obtain the noncollinear twisted magnetization depth profiles where the spin-flop state appears sequentially in different 57Fe layers at increasing applied field.

  5. Thermodynamic coupling of heat and matter flows in near-field regions of nuclear waste repositories

    SciTech Connect

    Carnahan, C.L.

    1983-11-01

    In near-field regions of nuclear waste repositories, thermodynamically coupled flows of heat and matter can occur in addition to the independent flows in the presence of gradients of temperature, hydraulic potential, and composition. The following coupled effects can occur: thermal osmosis, thermal diffusion, chemical osmosis, thermal filtration, diffusion thermal effect, ultrafiltration, and coupled diffusion. Flows of heat and matter associated with these effects can modify the flows predictable from the direct effects, which are expressed by Fourier's law, Darcy's law, and Fick's law. The coupled effects can be treated quantitatively together with the direct effects by the methods of the thermodynamics of irreversible processes. The extent of departure of fully coupled flows from predictions based only on consideration of direct effects depends on the strengths of the gradients driving flows, and may be significant at early times in backfills and in near-field geologic environments of repositories. Approximate calculations using data from the literature and reasonable assumptions of repository conditions indicate that thermal-osmotic and chemical-osmotic flows of water in semipermeable backfills may exceed Darcian flows by two to three orders of magnitude, while flows of solutes may be reduced greatly by ultrafiltration and chemical osmosis, relative to the flows predicted by advection and diffusion alone. In permeable materials, thermal diffusion may contribute to solute flows to a smaller, but still significant, extent.

  6. Polarizing agents and mechanisms for high-field dynamic nuclear polarization of frozen dielectric solids.

    PubMed

    Hu, Kan-Nian

    2011-09-01

    This article provides an overview of polarizing mechanisms involved in high-frequency dynamic nuclear polarization (DNP) of frozen biological samples at temperatures maintained using liquid nitrogen, compatible with contemporary magic-angle spinning (MAS) nuclear magnetic resonance (NMR). Typical DNP experiments require unpaired electrons that are usually exogenous in samples via paramagnetic doping with polarizing agents. Thus, the resulting nuclear polarization mechanism depends on the electron and nuclear spin interactions induced by the paramagnetic species. The Overhauser Effect (OE) DNP, which relies on time-dependent spin-spin interactions, is excluded from our discussion due the lack of conducting electrons in frozen aqueous solutions containing biological entities. DNP of particular interest to us relies primarily on time-independent, spin-spin interactions for significant electron-nucleus polarization transfer through mechanisms such as the Solid Effect (SE), the Cross Effect (CE) or Thermal Mixing (TM), involving one, two or multiple electron spins, respectively. Derived from monomeric radicals initially used in high-field DNP experiments, bi- or multiple-radical polarizing agents facilitate CE/TM to generate significant NMR signal enhancements in dielectric solids at low temperatures (<100 K). For example, large DNP enhancements (∼300 times at 5 T) from a biologically compatible biradical, 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL), have enabled high-resolution MAS NMR in sample systems existing in submicron domains or embedded in larger biomolecular complexes. The scope of this review is focused on recently developed DNP polarizing agents for high-field applications and leads up to future developments per the CE DNP mechanism. Because DNP experiments are feasible with a solid-state microwave source when performed at <20K, nuclear polarization using lower microwave power (<100 mW) is possible by forcing a high proportion of biradicals to

  7. Aging effects of US space nuclear systems in orbit

    SciTech Connect

    Bartram, B.W.; Huang, R.; Tammara, S.R.; Thielke, N.R.

    1982-05-14

    This report presents information and data in support of a cost-benefit analysis being performed by Fair child Industries (FI) on the feasibility of retrieving existing US space nuclear systems in earth orbit by the Space Shuttle. This report evaluates, for US space nuclear systems presently in orbit, the radioisotopic inventory and external radiation field as a function of time, the effect of aging on fuel containment materials over the projected lifetime of the system, and the possible radioactive source terms should reentry eventually occur. Although the radioisotopic inventories and radiation fields have been evaluated for all systems, Transit 4A and Transit Triad have been emphasized in the evaluation of the aging effects and reentry consequences because these spacecraft have the shortest projected orbital lifetimes (570 and 150 years, respectively). In addition to existing systems in orbit, the radioisotopic inventory, radiation field, and reentry source terms have been evaluated for a General Purpose Heat Source (GPHS) in a parking orbit due to an aborted Galileo Mission or International Solar Polar Mission (ISPM).

  8. Impact of an external radiation field on handheld XRF measurements for nuclear forensics applications

    SciTech Connect

    Steeb, Jennifer L.; Mertz, Carol J.; Finck, Martha R.; Engelstad, Gary; Carney, Kevin P.; Chamberlain, David B.

    2015-03-28

    X-ray fluorescence (XRF) is an attractive technique for nuclear forensics applications. We evaluated a handheld, portable XRF device by applying an external radiation field (10 mR/h to 17 R/h) using two types of radiography sources: a 60Co radiography camera to observe effects from high-energy gamma emissions and an 192Ir radiography camera to observe effects from several low-energy gamma (0.604, 0.468, and 0.317 MeV) and decay daughter x-ray emissions. External radiation tests proved that radiation, in general, has a significant effect on the dead time or background at dose rates over 1 R/hr for both the 192Ir and 60Co sources.

  9. Effects of realistic tensor force on nuclear structure

    SciTech Connect

    Nakada, H.

    2012-10-20

    First-order tensor-force effects on nuclear structure are investigated in the self-consistent mean-field and RPA calculations with the M3Y-type semi-realistic interactions, which contain the realistic tensor force. The tensor force plays a key role in Z- or N-dependence of the shell structure, and in transitions involving spin degrees-of-freedom. It is demonstrated that the semi-realistic interactions successfully describe the N-dependence of the shell structure in the proton-magic nuclei (e.g. Ca and Sn), and the magnetic transitions (e.g. M1 transition in {sup 208}Pb).

  10. Solar Magnetic Field: Zeeman and Hanle Effects

    NASA Astrophysics Data System (ADS)

    Stenflo, J.; Murdin, P.

    2001-10-01

    An external magnetic field causes the atomic energy levels to split into different sublevels, and the emitted radiation becomes polarized. This phenomenon is called the ZEEMAN EFFECT. When atoms in a magnetic field scatter radiation via bound-bound transitions, the phase relations or quantum interferences between the Zeeman-split sublevels give rise to POLARIZATION phenomena that go under the nam...

  11. Nuclear Winter: Uncertainties Surround the Long-Term Effects of Nuclear War. Report to the Congress.

    ERIC Educational Resources Information Center

    General Accounting Office, Washington, DC.

    Nuclear winter, a term used to describe potential long-term climate and environmental effects of nuclear war, has been a subject of debate and controversy. This report examines and presents scientific and policy implications of nuclear winter. Contents include: (1) an executive summary (highlighting previous and current studies on the topic); (2)…

  12. Nuclear-resonance magnetometer with flowing liquid for superstrong inhomogeneous fields measuring

    NASA Astrophysics Data System (ADS)

    Davydov, V. V.; Dudkin, V. I.; Vologdin, V. A.

    2016-03-01

    Multichannel nuclear-resonance magnetometer for remote monitoring of induction and heterogeneity of a magnetic field in different areas inside and near a charged particle accelerator is considered. The maximal distance between the nuclear magnetic resonance signal detector and the magnetometer is 50 m. Measurement error is 0.5%, sensitivity of the magnetometer is 10-10 T/Hz1/2, measurement time of the magnetic field parameters in 24 control points is no more than 4 minutes.

  13. Can realistic interaction be useful for nuclear mean-field approaches?

    NASA Astrophysics Data System (ADS)

    Nakada, H.; Sugiura, K.; Inakura, T.; Margueron, J.

    2016-07-01

    Recent applications of the M3Y-type semi-realistic interaction to the nuclear mean-field approaches are presented: i) Prediction of magic numbers and ii) isotope shifts of nuclei with magic proton numbers. The results exemplify that the realistic interaction, which is derived from the bare 2 N and 3 N interaction, furnishes a new theoretical instrument for advancing nuclear mean-field approaches.

  14. Polarization effects in molecular mechanical force fields.

    PubMed

    Cieplak, Piotr; Dupradeau, François-Yves; Duan, Yong; Wang, Junmei

    2009-08-19

    The focus here is on incorporating electronic polarization into classical molecular mechanical force fields used for macromolecular simulations. First, we briefly examine currently used molecular mechanical force fields and the current status of intermolecular forces as viewed by quantum mechanical approaches. Next, we demonstrate how some components of quantum mechanical energy are effectively incorporated into classical molecular mechanical force fields. Finally, we assess the modeling methods of one such energy component-polarization energy-and present an overview of polarizable force fields and their current applications. Incorporating polarization effects into current force fields paves the way to developing potentially more accurate, though more complex, parameterizations that can be used for more realistic molecular simulations. PMID:21828594

  15. Polarization effects in molecular mechanical force fields

    PubMed Central

    Cieplak, Piotr; Dupradeau, François-Yves; Duan, Yong; Wang, Junmei

    2014-01-01

    The focus here is on incorporating electronic polarization into classical molecular mechanical force fields used for macromolecular simulations. First, we briefly examine currently used molecular mechanical force fields and the current status of intermolecular forces as viewed by quantum mechanical approaches. Next, we demonstrate how some components of quantum mechanical energy are effectively incorporated into classical molecular mechanical force fields. Finally, we assess the modeling methods of one such energy component—polarization energy—and present an overview of polarizable force fields and their current applications. Incorporating polarization effects into current force fields paves the way to developing potentially more accurate, though more complex, parameterizations that can be used for more realistic molecular simulations. PMID:21828594

  16. Computer simulation of underwater nuclear effects

    SciTech Connect

    Kamegai, M.

    1987-01-30

    We investigated underwater nuclear effects by computer simulations. First, we computed a long distance wave propagation in water by the 1-D LASNEX code by modeling the energy source and the underwater environment. The pressure-distance data were calculated for two quite different yields; pressures range from 300 GPa to 15 MPa. They were found to be in good agreement with Snay's theoretical points and the Wigwam measurements. The computed data also agree with the similarity solution at high pressures and the empirical equation at low pressures. After completion of the 1-D study, we investigated a free surface effect commonly referred to as irregular surface rarefaction by applying two hydrocodes (LASNEX and ALE), linked at the appropriate time. Using these codes, we simulated near-surface explosions for three depths of burst (3 m, 21 m and 66.5 m), which represent the strong, intermediate, and weak surface shocks, respectively.

  17. Decommissioning and Cutting Methods in the Nuclear Field

    SciTech Connect

    Bensoussan, E.

    2008-07-01

    A few states started in the early forties/fifties the first development of nuclear technologies. Some of them now own a great amount of nuclear installations which entirely fulfil their assignment. In some cases, the life time of the nuclear power plants which were scheduled for approximately 30 years have been extended by more than 50%, the other ones as well as fuel production and enrichment plants, experimental or research reactors, will have to be dismantled in the near future. The decommissioning of those installations is definitely one of the twenty first century challenge. It is differently managed depending on the countries and their energetic and development policies, their financial consideration, the availability of qualified engineers or specialized companies to handle such projects. The final aim of decommissioning is to recover the geographic site in its original condition. A real cooperation is existing in between the people involved in different countries through different types of conferences and meetings during which the main subjects are: - The safety of the operators during all the phases of decommissioning operations; - Restrictions and dimensioning of the required equipment; - Storage and waste management; - Elaboration of procedures for recording all different steps and processes. Some of the techniques are described in this paper without being exhaustive: Hot cutting, oxy-fuel and plasma cutting; Band saw; Milling saw; Milling; Cutting tool; Wheel cutting; Shear cutting; And any other cutting processes or dismantling methods. (authors)

  18. HIGHER ORDER HARD EDGE END FIELD EFFECTS.

    SciTech Connect

    BERG,J.S.

    2004-09-14

    In most cases, nonlinearities from magnets must be properly included in tracking and analysis to properly compute quantities of interest, in particular chromatic properties and dynamic aperture. One source of nonlinearities in magnets that is often important and cannot be avoided is the nonlinearity arising at the end of a magnet due to the longitudinal variation of the field at the end of the magnet. Part of this effect is independent of the longitudinal of the end. It is lowest order in the body field of the magnet, and is the result of taking a limit as the length over which the field at the end varies approaches zero. This is referred to as a ''hard edge'' end field. This effect has been computed previously to lowest order in the transverse variables. This paper describes a method to compute this effect to arbitrary order in the transverse variables, under certain constraints.

  19. Effects of static magnetic fields on plants.

    NASA Astrophysics Data System (ADS)

    Kuznetsov, O.

    In our recent experiment on STS-107 (MFA-Biotube) we took advantage of the magnetic heterogeneity of the gravity receptor cells of flax roots, namely stronger diamagnetism of starch-filled amyloplasts compared to cytoplasm (Δ ≊ < 0). High gradient magnetic fields (HGMF, grad(H2/2) up to 109-1010 Oe2/cm) of the experimental chambers (MFCs) repelled amyloplasts from the zones of stronger field thus providing a directional stimulus for plant gravisensing system in microgravity, and causing the roots to react. Such reaction was observed in the video downlink pictures. Unfortunately, the ``Columbia'' tragedy caused loss of the plant material and most of the images, thus preventing us from detailed studies of the results. Currently we are looking for a possibility to repeat this experiment. Therefore, it is very important to understand, what other effects (besides displacing amyloplasts) static magnetic fields with intensities 0 to 2.5104 Oe, and with the size of the area of non-uniformity 10-3 to 1 cm. These effects were estimated theoretically and tested experimentally. No statistically significant differences in growth rates or rates of gravicurvature were observed in experiments with Linum, Arabidopsis, Hordeum, Avena, Ceratodon and Chara between the plants grown in uniform magnetic fields of various intensities (102 to 2.5104 Oe) and those grown in the Earth's magnetic field. Microscopic studies also did not detect any structural differences between test and control plants. The magnitudes of possible effects of static magnetic fields on plant cells and organs (including effects on ion currents, magneto-hydrodynamic effects in moving cytoplasm, ponderomotive forces on other cellular structures, effects on some biochemical reactions and biomolecules) were estimated theoretically. The estimations have shown, that these effects are small compared to the thermodynamic noise and thus are insignificant. Both theoretical estimations and control experiments confirm, that

  20. Polarizing Agents and Mechanisms for High-Field Dynamic Nuclear Polarization of Frozen Dielectric Solids

    PubMed Central

    Hu, Kan-Nian

    2011-01-01

    This article provides an overview of polarizing mechanisms involved in high-frequency dynamic nuclear polarization (DNP) of frozen biological samples at temperatures maintained using liquid nitrogen, compatible with contemporary magic-angle spinning (MAS) nuclear magnetic resonance (NMR). Typical DNP experiments require unpaired electrons that are usually exogenous in samples via paramagnetic doping with polarizing agents. Thus, the resulting nuclear polarization mechanism depends on the electron and nuclear spin interactions induced by the paramagnetic species. The Overhauser Effect (OE) DNP, which relies on time-dependent spin-spin interactions, is excluded from our discussion due the lack of conducting electrons in frozen aqueous solutions containing biological entities. DNP of particular interest to us relies primarily on time-independent, spin interactions for significant electron-nucleus polarization transfer through mechanisms such as the Solid Effect (SE), the Cross Effect (CE) or Thermal Mixing (TM), involving one, two or multiple electron spins, respectively. Derived from monomeric radicals initially used in DNP experiments, bi- or multiple-radical polarizing agents facilitate CE/TM to generate significant NMR signal enhancements in dielectric solids at low temperatures (< 100 K). For example, large DNP enhancements (~300 times at 5 T) from a biologically compatible biradical, 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL), have enabled high-resolution MAS NMR in sample systems existing in submicron domains or embedded in larger biomolecular complexes. The scope of this review is focused on recently developed DNP polarizing agents for high-field applications and leads up to future developments per the CE DNP mechanism. Because DNP experiments are feasible with a solid-state microwave source when performed at <20 K, nuclear polarization using lower microwave power (< 100 mW) is possible by forcing a high proportion of biradicals to fulfill the

  1. Connection between the nuclear matter mean-field equation of state and the quark and gluon condensates at high density

    SciTech Connect

    Malheiro, M.; Dey, M.; Delfino, A.; Dey, J. |||

    1997-01-01

    It is known now that chiral symmetry restoration requires the meson-nucleon couplings to be density-dependent in nuclear-matter mean-field models. We further show that, quite generally, the quark and gluon condensates in medium are related to the trace of the energy-momentum tensor of nuclear matter and in these models the incompressibility K must be less than 3 times the chemical potential {mu}. In the critical density {rho}{sub c}, the gluon condensate is only reduced by 20{percent}, indicating a larger effective nucleon mass. {copyright} {ital 1997} {ital The American Physical Society}

  2. Radiation fields and dose assessments in Korean nuclear power plants.

    PubMed

    Kim, Hee Geun; Kong, Tae Young; Jeong, Woo Tae; Kim, Seok Tae

    2011-07-01

    In the primary systems of nuclear power plants (NPPs), various radionuclides including fission products and corrosion products are generated due to the complex water chemistry conditions. In particular, (3)H, (14)C, (58)Co, (60)Co, (137)Cs, and (131)I are important or potential radionuclides with respect to dose assessment for workers and the management of radioactive effluents or dose assessment for the public. In this paper, the dominant contributors to the dose for workers and the public were reviewed and the process of dose assessment attributable to those contributors was investigated. Furthermore, an analysis was carried out on some examples of dose to workers during NPP operation. PMID:21498858

  3. Global anomalies and effective field theory

    NASA Astrophysics Data System (ADS)

    Golkar, Siavash; Sethi, Savdeep

    2016-05-01

    We show that matching anomalies under large gauge transformations and large diffeomorphisms can explain the appearance and non-renormalization of couplings in effective field theory. We focus on thermal effective field theory, where we argue that the appearance of certain unusual Chern-Simons couplings is a consequence of global anomalies. As an example, we show that a mixed global anomaly in four dimensions fixes the chiral vortical effect coefficient (up to an overall additive factor). This is an experimentally measurable prediction from a global anomaly. For certain situations, we propose a simpler method for calculating global anomalies which uses correlation functions rather than eta invariants.

  4. Magnetic field effects on microwave absorbing materials

    NASA Technical Reports Server (NTRS)

    Goldberg, Ira; Hollingsworth, Charles S.; Mckinney, Ted M.

    1991-01-01

    The objective of this program was to gather information to formulate a microwave absorber that can work in the presence of strong constant direct current (DC) magnetic fields. The program was conducted in four steps. The first step was to investigate the electrical and magnetic properties of magnetic and ferrite microwave absorbers in the presence of strong magnetic fields. This included both experimental measurements and a literature survey of properties that may be applicable to finding an appropriate absorbing material. The second step was to identify those material properties that will produce desirable absorptive properties in the presence of intense magnetic fields and determine the range of magnetic field in which the absorbers remain effective. The third step was to establish ferrite absorber designs that will produce low reflection and adequate absorption in the presence of intense inhomogeneous static magnetic fields. The fourth and final step was to prepare and test samples of such magnetic microwave absorbers if such designs seem practical.

  5. Reductionism, emergence, and effective field theories

    NASA Astrophysics Data System (ADS)

    Castellani, Elena

    In recent years, a "change in attitude" in particle physics has led to our understanding current quantum field theories as effective field theories (EFTs). The present paper is concerned with the significance of this EFT approach, especially from the viewpoint of the debate on reductionism in science. In particular, I shall show how EFTs provide a new and interesting case study in current philosophical discussion on reduction, emergence, and inter-level relationships in general.

  6. Diamond-nitrogen-vacancy electronic and nuclear spin-state anticrossings under weak transverse magnetic fields

    NASA Astrophysics Data System (ADS)

    Clevenson, Hannah; Chen, Edward H.; Dolde, Florian; Teale, Carson; Englund, Dirk; Braje, Danielle

    2016-08-01

    We report on detailed studies of electronic and nuclear spin states in the diamond-nitrogen-vacancy (NV) center under weak transverse magnetic fields. We numerically predict and experimentally verify a previously unobserved NV hyperfine level anticrossing (LAC) occurring at bias fields of tens of gauss—two orders of magnitude lower than previously reported LACs at ˜500 and ˜1000 G axial magnetic fields. We then discuss how the NV ground-state Hamiltonian can be manipulated in this regime to tailor the NV's sensitivity to environmental factors and to map into the nuclear spin state.

  7. Dynamic nuclear polarization and Hanle effect in (In,Ga)As/GaAs quantum dots. Role of nuclear spin fluctuations

    SciTech Connect

    Gerlovin, I. Ya.; Cherbunin, R. V.; Ignatiev, I. V.; Kuznetsova, M. S.; Verbin, S. Yu.; Flisinski, K.; Bayer, M.; Reuter, D.; Wieck, A. D.; Yakovlev, D. R.

    2013-12-04

    The degree of circular polarization of photoluminescence of (In,Ga)As quantum dots as a function of magnetic field applied perpendicular to the optical axis (Hanle effect) is experimentally studied. The measurements have been performed at various regimes of the optical excitation modulation. The analysis of experimental data has been performed in the framework of a vector model of regular nuclear spin polarization and its fluctuations. The analysis allowed us to evaluate the magnitude of nuclear polarization and its dynamics at the experimental conditions used.

  8. Effects of the Fukushima Daiichi nuclear accident on goshawk reproduction.

    PubMed

    Murase, Kaori; Murase, Joe; Horie, Reiko; Endo, Koichi

    2015-01-01

    Although the influence of nuclear accidents on the reproduction of top predators has not been investigated, it is important that we identify the effects of such accidents because humans are also top predators. We conducted field observation for 22 years and analysed the reproductive performance of the goshawk (Accipiter gentilis fujiyamae), a top avian predator in the North Kanto area of Japan, before and after the accidents at the Fukushima Daiichi nuclear power plant that occurred in 2011. The reproductive performance declined markedly compared with the pre-accident years and progressively decreased for the three post-accident study years. Moreover, it was suggested that these declines were primarily caused by an increase in the air dose rate of radio-active contaminants measured under the nests caused by the nuclear accidents, rather than by other factors. We consider the trends in the changes of the reproductive success rates and suggest that internal exposure may play an important role in the reproductive performance of the goshawk, as well as external exposure. PMID:25802117

  9. Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule

    NASA Astrophysics Data System (ADS)

    Cloët, Ian C.; Bentz, Wolfgang; Thomas, Anthony W.

    2016-01-01

    In light of the forthcoming high precision quasielastic electron scattering data from Jefferson Lab, it is timely for the various approaches to nuclear structure to make robust predictions for the associated response functions. With this in mind, we focus here on the longitudinal response function and the corresponding Coulomb sum rule for isospin-symmetric nuclear matter at various baryon densities. Using a quantum field-theoretic quark-level approach which preserves the symmetries of quantum chromodynamics, as well as exhibiting dynamical chiral symmetry breaking and quark confinement, we find a dramatic quenching of the Coulomb sum rule for momentum transfers |q |≳0.5 GeV . The main driver of this effect lies in changes to the proton Dirac form factor induced by the nuclear medium. Such a dramatic quenching of the Coulomb sum rule was not seen in a recent quantum Monte Carlo calculation for carbon, suggesting that the Jefferson Lab data may well shed new light on the explicit role of QCD in nuclei.

  10. Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule.

    PubMed

    Cloët, Ian C; Bentz, Wolfgang; Thomas, Anthony W

    2016-01-22

    In light of the forthcoming high precision quasielastic electron scattering data from Jefferson Lab, it is timely for the various approaches to nuclear structure to make robust predictions for the associated response functions. With this in mind, we focus here on the longitudinal response function and the corresponding Coulomb sum rule for isospin-symmetric nuclear matter at various baryon densities. Using a quantum field-theoretic quark-level approach which preserves the symmetries of quantum chromodynamics, as well as exhibiting dynamical chiral symmetry breaking and quark confinement, we find a dramatic quenching of the Coulomb sum rule for momentum transfers |q|≳0.5  GeV. The main driver of this effect lies in changes to the proton Dirac form factor induced by the nuclear medium. Such a dramatic quenching of the Coulomb sum rule was not seen in a recent quantum Monte Carlo calculation for carbon, suggesting that the Jefferson Lab data may well shed new light on the explicit role of QCD in nuclei. PMID:26849589

  11. Effects of the Fukushima Daiichi nuclear accident on goshawk reproduction

    PubMed Central

    Murase, Kaori; Murase, Joe; Horie, Reiko; Endo, Koichi

    2015-01-01

    Although the influence of nuclear accidents on the reproduction of top predators has not been investigated, it is important that we identify the effects of such accidents because humans are also top predators. We conducted field observation for 22 years and analysed the reproductive performance of the goshawk (Accipiter gentilis fujiyamae), a top avian predator in the North Kanto area of Japan, before and after the accidents at the Fukushima Daiichi nuclear power plant that occurred in 2011. The reproductive performance declined markedly compared with the pre-accident years and progressively decreased for the three post-accident study years. Moreover, it was suggested that these declines were primarily caused by an increase in the air dose rate of radio-active contaminants measured under the nests caused by the nuclear accidents, rather than by other factors. We consider the trends in the changes of the reproductive success rates and suggest that internal exposure may play an important role in the reproductive performance of the goshawk, as well as external exposure. PMID:25802117

  12. Three-body systems in pionless effective field theory

    NASA Astrophysics Data System (ADS)

    Vanasse, Jared

    2016-04-01

    Investigations of three-body nuclear systems using pionless effective field theory (EFTπ̸) are reviewed. The history of EFTπ̸ in nd and pd scattering is briefly discussed and emphasis put on the use of strict perturbative techniques. In addition renormalization issues appearing in pd scattering are also presented. Bound state calculations are addressed and new perturbative techniques for describing them are highlighted. Three-body breakup observables in nd scattering are also considered and the utility of EFTπ̸ for addressing them.

  13. The Solar hep Process in Effective Field Theory

    SciTech Connect

    T.-S. Park; L. E. Marcucci; R. Schiavilla; M. Viviani; A. Kievsky; S. Rosati; K. Kubodera; D.-P. Min; M. Rho

    2001-09-01

    Using effective field theory, we calculate the S-factor for the hep process in a totally parameter-free formulation. The transition operators are organized according to chiral counting, and their matrix elements are evaluated using the realistic nuclear wave functions obtained in the Correlated-hyperspherical-harmonics method. Terms of up to next-to-next-to-next-to-leading order in heavy-baryon chiral perturbation theory are considered. Fixing the only parameter in the theory by fitting the tritium beta-decay rate, we predict the hep S-factor with accuracy better than {approx} 20%.

  14. Electric field effects on droplet burning

    NASA Astrophysics Data System (ADS)

    Patyal, Advitya; Kyritsis, Dimitrios; Matalon, Moshe

    2015-11-01

    The effects of an externally applied electric field are studied on the burning characteristics of a spherically symmetric fuel drop including the structure, mass burning rate and extinction characteristics of the diffusion flame. A reduced three-step chemical kinetic mechanism that reflects the chemi-ionization process for general hydrocarbon fuels has been proposed to capture the production and destruction of ions inside the flame zone. Due to the imposed symmetry, the effect of the ionic wind is simply to modify the pressure field. Our study thus focuses exclusively on the effects of Ohmic heating and kinetic effects on the burning process. Two distinguished limits of weak and strong field are identified, highlighting the relative strength of the internal charge barrier compared to the externally applied field, and numerically simulated. For both limits, significantly different charged species distributions are observed. An increase in the mass burning rate is noticed with increasing field in either limit with negligible change in the flame temperature. Increasing external voltages pushes the flame away from the droplet and causes a strengthening of the flame with a reduction in the extinction Damkhöler number.

  15. Complementary junction heterostructure field-effect transistor

    DOEpatents

    Baca, Albert G.; Drummond, Timothy J.; Robertson, Perry J.; Zipperian, Thomas E.

    1995-01-01

    A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits.

  16. Complementary junction heterostructure field-effect transistor

    DOEpatents

    Baca, A.G.; Drummond, T.J.; Robertson, P.J.; Zipperian, T.E.

    1995-12-26

    A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits. 10 figs.

  17. Fractional effective action at strong electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Kleinert, Hagen; Strobel, Eckhard; Xue, She-Sheng

    2013-07-01

    In 1936, Weisskopf [K. Dan. Vidensk. Selsk. Mat. Fys. Medd. XIV (1936)] showed that for vanishing electric or magnetic fields the strong-field behavior of the one-loop Euler-Heisenberg effective Lagrangian of quantum electro dynamics (QED) is logarithmic. Here we generalize this result for different limits of the Lorentz invariants E→2-B→2 and B→·E→. The logarithmic dependence can be interpreted as a lowest-order manifestation of an anomalous power behavior of the effective Lagrangian of QED, with critical exponents δ=e2/(12π) for spinor QED, and δS=δ/4 for scalar QED.

  18. Observation of spin Hall effective field

    NASA Astrophysics Data System (ADS)

    Fan, Xin; Wu, Jun; Chen, Yunpeng; Jerry, Matthew; Zhang, Huaiwu; Xiao, John

    2013-03-01

    Recent development in spin Hall driven spin transfer torque has attracted intensive interests1. Liu et. al. has shown that the spin transfer torque induced by the spin Hall effect in a normal metal-ferromagnetic metal bilayer can switch the magnetization of the ferromagnetic layer, which may be a potential candidate for magnetic random access memory2. The switching of the magnetization was primarily attributed to the Slonczewski torque3. We show that besides the Slonczewski torque, the spin Hall effect also produces an effective field that can also facilitate the magnetization reversal. This effective field persists even with a Cu spacer layer, and reduces quickly with the increase of the ferromagnetic layer thickness. The observation of the spin Hall effective field shall have ramification on the understanding of both spin transfer torque and spin Hall effect. 1. K. Ando et. al., Electric manipulation of spin relaxation using the spin Hall effect, Physical Review Letters, 101, 036601 (2008). 2. L. Liu et. al., Spin-Torque Switching with the Giant Spin Hall Effect of Tantalum. Science 336, 555-558 (2012). 3. J. Slonczewski, Current-driven excitation of magnetic multilayers. Journal of Magnetism and Magnetic Materials, 159, L1-L7 (1996).

  19. The characterization of human compact bone structure changes by low-field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Ni, Qingwen; Derwin King, J.; Wang, Xiaodu

    2004-01-01

    A technique of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation is described for characterizing the porosity and (effective) pore size distribution in vitro in human compact bone. The technique involves spin spin relaxation measurement and inversion spin spin relaxation spectral analysis methods. The spin spin relaxation decay curve is converted into a T2 distribution spectrum by a sum of single exponential decays. The advantages of using low-field NMR for the spin spin relaxation technique are illustrated. The results obtained from NMR methodology are compared with the results obtained from currently available but destructive histomorphometry and mercury porosimetry methods. The NMR porosities correlate well with the results obtained from the histomorphometry measurements of eight samples from donors of ages 21 89 years. The pore size distributions from T2 relaxation measurements are similar to the distributions obtained from the mercury porosimetry and histomorphometry measurements. This indicates that the age-related porosity and pore size changes in human compact bone can be detected using the low-field NMR technique.

  20. Psychotherapist countertransference in the nuclear age: Effects on therapeutic interventions

    SciTech Connect

    Oderberg, N.A.

    1991-01-01

    Since the early 1980s, there has been considerable attention in the psychology literature to mental health problems related to living in a world threatened by nuclear destruction. Questionnaires were mailed to 630 psychotherapists from the Colorado Psychological Association, California Psychotherapists for Social Responsibility, California Psychologists for Social Responsibility, the US Army, and the APA Division of Military Psychology; 174 questionnaires were returned. It was hypothesized that liberalism, nuclear weapons opposition, nuclear concern, nuclear awareness, and anti-nuclear activism in psychotherapists would facilitate perception of, and openness to working with, a client's nuclear concerns and thus, would be positively correlated with intentions to discuss nuclear issues with clients in three different clinical vignettes. Results indicated that when controlling for subject group, psychotherapy orientation, age, sex, and income, all five independent variables were positively correlated with responses to all three clinical vignettes, with nuclear concern having the strongest unique effect in accounting for variance in responses to the vignettes.

  1. Plasma wave instability in a quantum field effect transistor with magnetic field effect

    SciTech Connect

    Zhang, Li-Ping; Xue, Ju-Kui

    2013-08-15

    The current-carrying state of a nanometer Field Effect Transistor (FET) may become unstable against the generation of high-frequency plasma waves and lead to generation of terahertz radiation. In this paper, the influences of magnetic field, quantum effects, electron exchange-correlation, and thermal motion of electrons on the instability of the plasma waves in a nanometer FET are reported. We find that, while the electron exchange-correlation suppresses the radiation power, the magnetic field, the quantum effects, and the thermal motion of electrons can enhance the radiation power. The radiation frequency increases with quantum effects and thermal motion of electrons, but decreases with electron exchange-correlation effect. Interestingly, we find that magnetic field can suppress the quantum effects and the thermal motion of electrons and the radiation frequency changes non-monotonely with the magnetic field. These properties could make the nanometer FET advantageous for realization of practical terahertz oscillations.

  2. Generation of low-frequency electric and magnetic fields during large- scale chemical and nuclear explosions

    SciTech Connect

    Adushkin, V.V.; Dubinya, V.A.; Karaseva, V.A.; Soloviev, S.P.; Surkov, V.V.

    1995-06-01

    We discuss the main parameters of the electric field in the surface layer of the atmosphere and the results of the investigations of the natural electric field variations. Experimental investigations of the electromagnetic field for explosions in air are presented. Electromagnetic signals generated by underground nuclear and chemical explosions are discussed and explosions for 1976--1991 are listed. Long term anomalies of the earth`s electromagnetic field in the vicinity of underground explosions were also investigated. Study of the phenomenon of the irreversible shock magnetization showed that in the zone nearest to the explosion the quasistatic magnetic field decreases in inverse proportion to the distance.

  3. Screening Nuclear Field Fluctuations in Quantum Dots for Indistinguishable Photon Generation.

    PubMed

    Malein, R N E; Santana, T S; Zajac, J M; Dada, A C; Gauger, E M; Petroff, P M; Lim, J Y; Song, J D; Gerardot, B D

    2016-06-24

    A semiconductor quantum dot can generate highly coherent and indistinguishable single photons. However, intrinsic semiconductor dephasing mechanisms can reduce the visibility of two-photon interference. For an electron in a quantum dot, a fundamental dephasing process is the hyperfine interaction with the nuclear spin bath. Here, we directly probe the consequence of the fluctuating nuclear spins on the elastic and inelastic scattered photon spectra from a resident electron in a single dot. We find the in-plane component of the nuclear Overhauser field leads to detuned Raman scattered photons, broadened over experimental time scales by field fluctuations, which are distinguishable from both the elastic and incoherent components of the resonance fluorescence. This significantly reduces two-photon interference visibility. However, we demonstrate successful screening of the nuclear spin noise, which enables the generation of coherent single photons that exhibit high visibility two-photon interference. PMID:27391751

  4. Screening Nuclear Field Fluctuations in Quantum Dots for Indistinguishable Photon Generation

    NASA Astrophysics Data System (ADS)

    Malein, R. N. E.; Santana, T. S.; Zajac, J. M.; Dada, A. C.; Gauger, E. M.; Petroff, P. M.; Lim, J. Y.; Song, J. D.; Gerardot, B. D.

    2016-06-01

    A semiconductor quantum dot can generate highly coherent and indistinguishable single photons. However, intrinsic semiconductor dephasing mechanisms can reduce the visibility of two-photon interference. For an electron in a quantum dot, a fundamental dephasing process is the hyperfine interaction with the nuclear spin bath. Here, we directly probe the consequence of the fluctuating nuclear spins on the elastic and inelastic scattered photon spectra from a resident electron in a single dot. We find the in-plane component of the nuclear Overhauser field leads to detuned Raman scattered photons, broadened over experimental time scales by field fluctuations, which are distinguishable from both the elastic and incoherent components of the resonance fluorescence. This significantly reduces two-photon interference visibility. However, we demonstrate successful screening of the nuclear spin noise, which enables the generation of coherent single photons that exhibit high visibility two-photon interference.

  5. Solving the eigenvalue problem of the nuclear Yukawa-folded mean-field Hamiltonian

    NASA Astrophysics Data System (ADS)

    Dobrowolski, A.; Pomorski, K.; Bartel, J.

    2016-02-01

    The nuclear Hamiltonian with a Yukawa-folded mean-field potential is diagonalized within the basis of a deformed harmonic-oscillator in Cartesian coordinates. The nuclear shape is characterized by the equivalent sharp surface described either by the well known Funny-Hills or the Trentalange-Koonin-Sierk parametrizations. They are both able to describe a very vast variety of nuclear deformations, including necked-in shapes, left-right asymmetry and non-axiality. The only imposed limitation on the nuclear shape is the z-signature symmetry, which corresponds to a symmetry of the shape with respect to a rotation by an angle π around the z-axis. On output, the computer code produces for a given nucleus with mass number A and charge number Z the energy eigenvalues and eigenfunctions of the mean-field Hamiltonian at chosen deformation.

  6. Magnetocaloric effect in strong magnetic fields

    NASA Astrophysics Data System (ADS)

    Tishin, A. M.

    Calculations of magnetic entropy change, Δ SM, and magnetocaloric effect, Δ T, in 3d and 4f magnetics have been carried out, based on the molecular field theory. Δ SM and Δ T have been studied as a function of Debye temperature, θ D, Lande factor, gj, quantum number of total mechanical momentum, J, and also of magnetic phase transition temperatures. Limiting values of Δ SM and Δ T have been determined in extremely strong magnetic fields. The results obtained are compared with experimental data. It is shown that the use of ferromagnetic alloys Tb x Gd 1-x as operating devices of magnetic refrigerating machines in the room temperature range is more efficient than the use of pure Gd. These alloys have been found to have high specific refrigerant capacity over a wide range of fields from 0.1 to 6 T, which enables one to develop highly economic refrigeration devices in which weak fields are applied.

  7. Applied-field MPD thruster geometry effects

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.

    1991-01-01

    Eight MPD thruster configurations were used to study the effects of applied field strength, propellant, and facility pressure on thruster performance. Vacuum facility background pressures higher than approx. 0.12 Pa were found to greatly influence thruster performance and electrode power deposition. Thrust efficiency and specific impulse increased monotonically with increasing applied field strength. Both cathode and anode radii fundamentally influenced the efficiency specific impulse relationship, while their lengths influence only the magnitude of the applied magnetic field required to reach a given performance level. At a given specific impulse, large electrode radii result in lower efficiencies for the operating conditions studied. For all test conditions, anode power deposition was the largest efficiency loss, and represented between 50 and 80 pct. of the input power. The fraction of the input power deposited into the anode decreased with increasing applied field and anode radii. The highest performance measured, 20 pct. efficiency at 3700 seconds specific impulse, was obtained using hydrogen propellant.

  8. Toward understanding the effects of nuclear war

    SciTech Connect

    Grover, H.D.; White, G.F.

    1985-10-01

    The authors discuss the scientific justifications for studying the consequences of nuclear war. The consequences of nuclear war and nuclear winter - biotic impoverishment, climate change, pollution of the air, water, and soil - recapitulate in compressed time the patterns of ecological change humankind is even now imposing on the planet. By studying the biological consequences of nuclear war, important discoveries about the intricate nature of the global ecosystem may be made. Wiser management practices and more thorough appreciation of alterations in the physical and biological environment could results.

  9. Unified description of structure and reactions: implementing the nuclear field theory program

    NASA Astrophysics Data System (ADS)

    Broglia, R. A.; Bortignon, P. F.; Barranco, F.; Vigezzi, E.; Idini, A.; Potel, G.

    2016-06-01

    The modern theory of the atomic nucleus results from the merging of the liquid drop model of Niels Bohr and Fritz Kalckar, and of the shell model of Marie Goeppert Meyer and Hans Jensen. The first model contributed the concepts of collective excitations. The second, those of independent-particle motion. The unification of these apparently contradictory views in terms of the particle-vibration and particle-rotation couplings carried out by Aage Bohr and Ben Mottelson has allowed for an ever more complete, accurate and detailed description of nuclear structure. Nuclear field theory (NFT), developed by the Copenhagen–Buenos Aires collaboration, provided a powerful quantal embodiment of this unification. Reactions are not only at the basis of quantum mechanics (statistical interpretation, Max Born), but also the specific tools to probe the atomic nucleus. It is then natural that NFT is being extended to deal with processes which involve the continuum in an intrinsic fashion, so as to be able to treat them on an equal footing with those associated with bound states (structure). As a result, spectroscopic studies of transfer to continuum states could eventually make use of the NFT rules, properly extended to take care of recoil effects. In the present contribution we review the implementation of the NFT program of structure and reactions, setting special emphasis on open problems and outstanding predictions.

  10. Permeabilization of the nuclear envelope following nanosecond pulsed electric field exposure.

    PubMed

    Thompson, Gary L; Roth, Caleb C; Kuipers, Marjorie A; Tolstykh, Gleb P; Beier, Hope T; Ibey, Bennett L

    2016-01-29

    Permeabilization of cell membranes occurs upon exposure to a threshold absorbed dose (AD) of nanosecond pulsed electric fields (nsPEF). The ultimate, physiological bioeffect of this exposure depends on the type of cultured cell and environment, indicating that cell-specific pathways and structures are stimulated. Here we investigate 10 and 600 ns duration PEF effects on Chinese hamster ovary (CHO) cell nuclei, where our hypothesis is that pulse disruption of the nuclear envelope membrane leads to observed cell death and decreased viability 24 h post-exposure. To observe short-term responses to nsPEF exposure, CHO cells have been stably transfected with two fluorescently-labeled proteins known to be sequestered for cellular chromosomal function within the nucleus - histone-2b (H2B) and proliferating cell nuclear antigen (PCNA). H2B remains associated with chromatin after nsPEF exposure, whereas PCNA leaks out of nuclei permeabilized by a threshold AD of 10 and 600 ns PEF. A downturn in 24 h viability, measured by MTT assay, is observed at the number of pulses required to induce permeabilization of the nucleus. PMID:26721436

  11. Electric Field Effects in RUS Measurements

    SciTech Connect

    Darling, Timothy W; Ten Cate, James A; Allured, Bradley; Carpenter, Michael A

    2009-09-21

    Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material - a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the 'statistical residual' strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods.

  12. Electric field effects in RUS measurements.

    PubMed

    Darling, Timothy W; Allured, Bradley; Tencate, James A; Carpenter, Michael A

    2010-02-01

    Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material--a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the "statistical residual" strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods. PMID:19850314

  13. Nuclear excitation via the motion of electrons in a strong laser field

    SciTech Connect

    Berger, J.F.; Gogny, D.; Weiss, M.S.

    1987-12-01

    A method of switching from a nuclear isomeric state to a lasing state is examined. A semi-classical model of laser-electron-nuclear coupling is developed. In it the electrons are treated as free in the external field of the laser, but with initial conditions corresponding to their atomic orbits. Application is made to testing this model in /sup 235/U and to the design criteria of a gamma-ray laser. 14 refs., 2 tabs.

  14. A description of a wide beam saddle field ion source used for nuclear target applications

    SciTech Connect

    Greene, J.P.; Schiel, S.L.; Thomas, G.E.

    1997-07-01

    A description is given of a new, wide beam saddle field sputter source used for the preparation of targets applied in nuclear physics experiments. The ion source characteristics are presented and compared with published results obtained with other sources. Deposition rates acquired utilizing this source are given for a variety of target materials encountered in nuclear target production. New applications involving target thinning and ion milling are discussed.

  15. Individual SWCNT based ionic field effect transistor

    NASA Astrophysics Data System (ADS)

    Pang, Pei; He, Jin; Park, Jae Hyun; Krstic, Predrag; Lindsay, Stuart

    2011-03-01

    Here we report that the ionic current through a single-walled carbon nanotube (SWCNT) can be effectively gated by a perpendicular electrical field from a top gate electrode, working as ionic field effect transistor. Both our experiment and simulation confirms that the electroosmotic current (EOF) is the main component in the ionic current through the SWCNT and is responsible for the gating effect. We also studied the gating efficiency as a function of solution concentration and pH and demonstrated that the device can work effectively in the physiological relevant condition. This work opens the door to use CNT based nanofluidics for ion and molecule manipulation. This work was supported by the DNA Sequencing Technology Program of the National Human Genome Research Institute (1RC2HG005625-01, 1R21HG004770-01), Arizona Technology Enterprises and the Biodesign Institute.

  16. Effective Field Theory for Jet Processes

    NASA Astrophysics Data System (ADS)

    Becher, Thomas; Neubert, Matthias; Rothen, Lorena; Shao, Ding Yu

    2016-05-01

    Processes involving narrow jets receive perturbative corrections enhanced by logarithms of the jet opening angle and the ratio of the energies inside and outside the jets. Analyzing cone-jet processes in effective field theory, we find that in addition to soft and collinear fields their description requires degrees of freedom that are simultaneously soft and collinear to the jets. These collinear-soft particles can resolve individual collinear partons, leading to a complicated multi-Wilson-line structure of the associated operators at higher orders. Our effective field theory provides, for the first time, a factorization formula for a cone-jet process, which fully separates the physics at different energy scales. Its renormalization-group equations control all logarithmically enhanced higher-order terms, in particular also the nonglobal logarithms.

  17. Effective Field Theory for Jet Processes.

    PubMed

    Becher, Thomas; Neubert, Matthias; Rothen, Lorena; Shao, Ding Yu

    2016-05-13

    Processes involving narrow jets receive perturbative corrections enhanced by logarithms of the jet opening angle and the ratio of the energies inside and outside the jets. Analyzing cone-jet processes in effective field theory, we find that in addition to soft and collinear fields their description requires degrees of freedom that are simultaneously soft and collinear to the jets. These collinear-soft particles can resolve individual collinear partons, leading to a complicated multi-Wilson-line structure of the associated operators at higher orders. Our effective field theory provides, for the first time, a factorization formula for a cone-jet process, which fully separates the physics at different energy scales. Its renormalization-group equations control all logarithmically enhanced higher-order terms, in particular also the nonglobal logarithms. PMID:27232017

  18. CADAT field-effect-transistor simulator

    NASA Technical Reports Server (NTRS)

    1981-01-01

    CADAT field-effect transistor simulator (FETSIM) analyzes dc and transient behavior of metal-oxide-semiconductor (MOS) circuits. Both N-MOS and P-MOS transistor configurations in either bulk of silicon-on-sapphire (SOS) technology and almost any combination of R/C elements are analyzed.

  19. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, J.C.; Shul, R.J.

    1999-02-02

    An ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same are disclosed. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorus co-implantation, in selected III-V semiconductor materials. 19 figs.

  20. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, John C.; Shul, Randy J.

    1999-01-01

    An all-ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorous co-implantation, in selected III-V semiconductor materials.

  1. Integrated battlefield-effects research for the National Training Center. Appendix H. Designs of nuclear and chemical field simulators for the National Training Center. Technical report, 13 June 1983-30 December 1984

    SciTech Connect

    Erickson, D.; Ickler, J.; McKeown, P.; Metzger, L.; Plock, R.

    1984-12-31

    This report concludes that a common control system based on Motorola paging systems, using off-the-shelf commercial hardware, appears to be the most cost-effective approach. In regard to the chemical detector simulator, there is considerable risk associated with the design based on activating an actual M-43 detector with a harmless chemical. This is the most cost-effective design if (1) a harmless chemical will reliably activate the M-43 detector (2) there are enough M-43 detectors in the hands of troops undergoing training and (3) the degradation of M-43s resulting from use in field exercises is acceptable. There were not sufficient M-43s available for test to resolve whether a harmless chemical will reliably activate the detector. If the use of actual M-43 detectors is not feasible, an alternate design for a simple simulator appears most cost-effective. Designs for both approaches are provided. A design for a radiacmeter simulator has been provided using a clock mechanism for a meter movement.

  2. Microbial Effects on Nuclear Waste Packaging Materials

    SciTech Connect

    Horn, J; Martin, S; Carrillo, C; Lian, T

    2005-07-22

    Microorganisms may enhance corrosion of components of planned engineered barriers within the proposed nuclear waste repository at Yucca Mountain (YM). Corrosion could occur either directly, through processes collectively known as Microbiologically Influenced Corrosion (MIC), or indirectly, by adversely affecting the composition of water or brines that come into direct contact with engineered barrier surfaces. Microorganisms of potential concern (bacteria, archea, and fungi) include both those indigenous to Yucca Mountain and those that infiltrate during repository construction and after waste emplacement. Specific aims of the experimental program to evaluate the potential of microorganisms to affect damage to engineered barrier materials include the following: Indirect Effects--(1) Determine the limiting factors to microbial growth and activity presently in the YM environment. (2) Assess these limiting factors to aid in determining the conditions and time during repository evolution when MIC might become operant. (3) Evaluate present bacterial densities, the composition of the YM microbial community, and determining bacterial densities if limiting factors are overcome. During a major portion of the regulatory period, environmental conditions that are presently extant become reestablished. Therefore, these studies ascertain whether biomass is sufficient to cause MIC during this period and provide a baseline for determining the types of bacterial activities that may be expected. (4) Assess biogenic environmental effects, including pH, alterations to nitrate concentration in groundwater, the generation of organic acids, and metal dissolution. These factors have been shown to be those most relevant to corrosion of engineered barriers. Direct Effects--(1) Characterize and quantify microbiological effects on candidate containment materials. These studies were carried out in a number of different approaches, using whole YM microbiological communities, a subset of YM

  3. Electromagnetic fields-Part 1; Biological effects

    SciTech Connect

    Nair, I.; Morgan, M.G. )

    1990-08-01

    It is known that low-frequency electric and magnetic fields can produce a variety of effects in biological systems. Pulsed magnetic fields, for instance, are used to mend broken bones, and other beneficial medical applications are being developed. But in more chronic and less controlled environments, can exposure to such fields also pose health risks No one knows. Today that possibility, however, requires serious consideration. Though present knowledge is fragmentary, and a coherent theory to explain the observations seems far off, the continuous presence of power-frequency fields in the modern environment makes potential health effects a matter of serious scientific and public health policy concern. That concern has focused on cancer - especially leukemia and brain tumors - and developmental abnormalities, and, to a lesser extent on endocrine and nervous system disorders, including chronic depression. The authors focus on 60-hertz fields, where the mechanism of interaction probably involves the cell membrane, is nonlinear, and may act by causing some cooperative phenomena among the components of the cell membrane.

  4. Nuclear effects in atmospheric and accelerator neutrino experiments

    SciTech Connect

    Chauhan, S.; Athar, M. Sajjad; Singh, S. K.

    2010-11-24

    We have studied the nuclear medium effects in the neutrino (antineutrino) induced interactions in nuclei at intermediate energy region. We have applied this study to calculate the event rates for atmospheric and accelerator neutrino experiments. The study of the nuclear effects has been done for the quasielastic lepton production and the charged current incoherent and coherent pion production processes.

  5. Abnormal Magnetic Field Effects on Electrogenerated Chemiluminescence

    NASA Astrophysics Data System (ADS)

    Pan, Haiping; Shen, Yan; Wang, Hongfeng; He, Lei; Hu, Bin

    2015-03-01

    We report abnormal magnetic field effects on electrogenerated chemiluminescence (MFEECL) based on triplet emission from the Ru(bpy)3Cl2-TPrA electrochemical system: the appearance of MFEECL after magnetic field ceases. In early studies the normal MFEECL have been observed from electrochemical systems during the application of magnetic field. Here, the abnormal MFEECL suggest that the activated charge-transfer [Ru(bpy)33+ … TPrA•] complexes may become magnetized in magnetic field and experience a long magnetic relaxation after removing magnetic field. Our analysis indicates that the magnetic relaxation can gradually increase the density of charge-transfer complexes within reaction region due to decayed magnetic interactions, leading to a positive component in the abnormal MFEECL. On the other hand, the magnetic relaxation facilitates an inverse conversion from triplets to singlets within charge-transfer complexes. The inverse triplet --> singlet conversion reduces the density of triplet light-emitting states through charge-transfer complexes and gives rise to a negative component in the abnormal MFEECL. The combination of positive and negative components can essentially lead to a non-monotonic profile in the abnormal MFEECL after ceasing magnetic field. Nevertheless, our experimental studies may reveal un-usual magnetic behaviors with long magnetic relaxation from the activated charge-transfer [Ru(bpy)33+ … TPrA•] complexes in solution at room temperature.

  6. Abnormal magnetic field effects on electrogenerated chemiluminescence.

    PubMed

    Pan, Haiping; Shen, Yan; Wang, Hongfeng; He, Lei; Hu, Bin

    2015-01-01

    We report abnormal magnetic field effects on electrogenerated chemiluminescence (MFEECL) based on triplet emission from the Ru(bpy)3Cl2-TPrA electrochemical system: the appearance of MFEECL after magnetic field ceases. In early studies the normal MFEECL have been observed from electrochemical systems during the application of magnetic field. Here, the abnormal MFEECL suggest that the activated charge-transfer [Ru(bpy)3(3+) … TPrA(•)] complexes may become magnetized in magnetic field and experience a long magnetic relaxation after removing magnetic field. Our analysis indicates that the magnetic relaxation can gradually increase the density of charge-transfer complexes within reaction region due to decayed magnetic interactions, leading to a positive component in the abnormal MFEECL. On the other hand, the magnetic relaxation facilitates an inverse conversion from triplets to singlets within charge-transfer complexes. The inverse triplet → singlet conversion reduces the density of triplet light-emitting states through charge-transfer complexes and gives rise to a negative component in the abnormal MFEECL. The combination of positive and negative components can essentially lead to a non-monotonic profile in the abnormal MFEECL after ceasing magnetic field. Nevertheless, our experimental studies may reveal un-usual magnetic behaviors with long magnetic relaxation from the activated charge-transfer [Ru(bpy)3(3+) … TPrA(•)] complexes in solution at room temperature. PMID:25772580

  7. Abnormal Magnetic Field Effects on Electrogenerated Chemiluminescence

    PubMed Central

    Pan, Haiping; Shen, Yan; Wang, Hongfeng; He, Lei; Hu, Bin

    2015-01-01

    We report abnormal magnetic field effects on electrogenerated chemiluminescence (MFEECL) based on triplet emission from the Ru(bpy)3Cl2-TPrA electrochemical system: the appearance of MFEECL after magnetic field ceases. In early studies the normal MFEECL have been observed from electrochemical systems during the application of magnetic field. Here, the abnormal MFEECL suggest that the activated charge-transfer [Ru(bpy)33+ … TPrA•] complexes may become magnetized in magnetic field and experience a long magnetic relaxation after removing magnetic field. Our analysis indicates that the magnetic relaxation can gradually increase the density of charge-transfer complexes within reaction region due to decayed magnetic interactions, leading to a positive component in the abnormal MFEECL. On the other hand, the magnetic relaxation facilitates an inverse conversion from triplets to singlets within charge-transfer complexes. The inverse triplet → singlet conversion reduces the density of triplet light-emitting states through charge-transfer complexes and gives rise to a negative component in the abnormal MFEECL. The combination of positive and negative components can essentially lead to a non-monotonic profile in the abnormal MFEECL after ceasing magnetic field. Nevertheless, our experimental studies may reveal un-usual magnetic behaviors with long magnetic relaxation from the activated charge-transfer [Ru(bpy)33+ … TPrA•] complexes in solution at room temperature. PMID:25772580

  8. Multiconfiguration time-dependent Hartree approach for electron-nuclear correlation in strong laser fields

    SciTech Connect

    Jhala, Chirag; Lein, Manfred

    2010-06-15

    The multiconfiguration time-dependent Hartree approach is applied to study the electron-nuclear correlation in the dynamics of molecules subject to strong external laser fields, using the example of a model hydrogen molecular ion. The ground state of the system is well described by as few as two single-particle functions per degree of freedom. A significantly larger but moderate number of configurations is required to predict laser-induced fragmentation probabilities and high-order harmonic generation spectra accurately, showing that the correlation between electronic and nuclear degree of freedom is strongly increased by the presence of the laser field.

  9. Functional organic field-effect transistors.

    PubMed

    Guo, Yunlong; Yu, Gui; Liu, Yunqi

    2010-10-25

    Functional organic field-effect transistors (OFETs) have attracted increasing attention in the past few years due to their wide variety of potential applications. Research on functional OFETs underpins future advances in organic electronics. In this review, different types of functional OFETs including organic phototransistors, organic memory FETs, organic light emitting FETs, sensors based on OFETs and other functional OFETs are introduced. In order to provide a comprehensive overview of this field, the history, current status of research, main challenges and prospects for functional OFETs are all discussed. PMID:20853375

  10. Effective field theory for deformed atomic nuclei

    NASA Astrophysics Data System (ADS)

    Papenbrock, T.; Weidenmüller, H. A.

    2016-05-01

    We present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband E2 transitions. For rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.

  11. Effective field theory for deformed atomic nuclei

    DOE PAGESBeta

    Papenbrock, Thomas F.; Weidenmüller, H. A.

    2016-04-13

    In this paper, we present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband E2 transitions. Finally, for rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.

  12. Biological effects of electric fields: EPRI's role

    SciTech Connect

    Kavet, R.

    1982-07-01

    Since 1973 the Electric Power Research Institute (EPRI) has supported research to evaluate the biological effects which may result from exposure to electric fields produced by AC overhead transmission lines; more recently, EPRI has also begun DC research. Through 1981 EPRI will have expended $8.7M on these efforts. Ongoing AC projects are studying a variety of lifeforms exposed to electric fields; these include humans, miniature swine, rats, honeybees, chick embryos, and crops. The status of these projects is discussed. The DC program has not as yet produced data. These studies will add to the current data base so as to enable a more complete assessment of health risks which may be associated with exposure to electric fields at power frequencies.

  13. Electric field effect in "metallic" polymers

    NASA Astrophysics Data System (ADS)

    Hsu, Fang-Chi

    The charge transport properties of the "metallic" polymer, poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonic acid) (PEDOT:PSS), with a conductivity around 30 S/cm are studied in this thesis. The PEDOT:PSS is incorporated into a field effect transistor (FET) structure as an active component. Considering the screening effect of metals, it is unexpected to observe a dramatic conductance change in PEDOT:PSS under the application of a gate electric field. The conventional FET model is used to further investigate this phenomenon. Though the current-voltage (I-V) characteristics of PEDOT:PSS devices are similar to the conventional field effect transistors (FETs), the extracted field effect mobility (mu FET) from I-V curves is two orders of magnitude larger than that estimated from the conductivity. Further investigating the I-V curves, a hysteresis behavior is observed and varies with drain voltage sweeping rate. This hysteresis phenomenon suggests ion motion is involved in the PEDOT:PSS conductance suppression. Since the structure of the metallic polymers is viewed as metallic ordered regions embedded in poorly conducting disordered media, charge carriers conduct electricity by hopping over or resonant tunneling through the localized states in the disordered regions. Therefore, several experiments are performed to understand the origin of the electric field penetration inside the metallic polymer. Using the transient current measurements, the relationship between inserted ion charges and PEDOT:PSS conductance variation is examined. Around 2% replacement of hole charges on the PEDOT:PSS backbone with inserted ionic charges enables the modulation of the conductance of PEDOT:PSS by three orders of magnitude. This small fraction of charge compensation of counterions by inserted ion charges suggests a percolation phenomenon for PEDOT:PSS conduction suppression. The role of inserted ions is further investigated by measurements of the temperature dependence of

  14. Interfacial fields in organic field-effect transistors and sensors

    NASA Astrophysics Data System (ADS)

    Dawidczyk, Thomas J.

    Organic electronics are currently being commercialized and present a viable alternative to conventional electronics. These organic materials offer the ability to chemically manipulate the molecule, allowing for more facile mass processing techniques, which in turn reduces the cost. One application where organic semiconductors (OSCs) are being investigated is sensors. This work evaluates an assortment of n- and p-channel semiconductors as organic field-effect transistor (OFET) sensors. The sensor responses to dinitrotoluene (DNT) vapor and solid along with trinitrotoluene (TNT) solid were studied. Different semiconductor materials give different magnitude and direction of electrical current response upon exposure to DNT. Additional OFET parameters---mobility and threshold voltage---further refine the response to the DNT with each OFET sensor requiring a certain gate voltage for an optimized response to the vapor. The pattern of responses has sufficient diversity to distinguish DNT from other vapors. To effectively use these OFET sensors in a circuit, the threshold voltage needs to be tuned for each transistor to increase the efficiency of the circuit and maximize the sensor response. The threshold voltage can be altered by embedding charges into the dielectric layer of the OFET. To study the quantity and energy of charges needed to alter the threshold voltage, charge carriers were injected into polystyrene (PS) and investigated with scanning Kelvin probe microscopy (SKPM) and thermally stimulated discharge current (TSDC). Lateral heterojunctions of pentacene/PS were scanned using SKPM, effectively observing polarization along a side view of a lateral nonvolatile organic field-effect transistor dielectric interface. TSDC was used to observe charge migration out of PS films and to estimate the trap energy level inside the PS, using the initial rise method. The process was further refined to create lateral heterojunctions that were actual working OFETs, consisting of a

  15. Assessment of structural changes of human teeth by low-field nuclear magnetic resonance (NMR)

    NASA Astrophysics Data System (ADS)

    Ni, Qingwen; Chen, Shuo

    2010-01-01

    A technique of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation is described for assessment of age-related structural changes (dentin and pulp) of human teeth in vitro. The technique involves spin-spin relaxation measurement and inversion spin-spin spectral analysis methods. The spin-spin relaxation decay curve is converted into a T2 distribution spectrum by a sum of single exponential decays. The NMR spectra from the extracted dentin-portion-only and dental pulp-cells-only were compared with the whole extracted teeth spectra, for the dentin and pulp peak assignments. While dentin and pulp are highly significant parameters in determining tooth quality, variations in these parameters with age can be used as an effective tool for estimating tooth quality. Here we propose an NMR calibration method—the ratio of the amount of dentin to the amount of pulp obtained from NMR T2 distribution spectra can be used for measuring the age-related structural changes in teeth while eliminating any variations in size of teeth. Eight teeth (third molars) extracted from humans, aged among 17-67 years old, were tested in this study. It is found that the intensity ratio of dentin to pulp sensitively changes from 0.48 to 3.2 approaching a linear growth with age. This indicates that age-related structural changes in human teeth can be detected using the low-field NMR technique.

  16. Nuclear magnetic resonance in magnets with a helicoidal magnetic structure in an external magnetic field

    NASA Astrophysics Data System (ADS)

    Tankeyev, A. P.; Borich, M. A.; Smagin, V. V.

    2014-11-01

    In this review, the static and dynamic properties of a magnet with a helicoidal magnetic structure placed in an external magnetic field are discussed. The results of the investigation of its ground state and spectra, as well as the amplitudes of the spin excitations are presented. The temperature and field dependences of the basic thermodynamic characteristics (heat capacity, magnetization, and magnetic susceptibility) have been calculated in the spin-wave approximation. The results of calculating the local and integral dynamic magnetic susceptibility are given. This set of data represents a methodical basis for constructing a consistent (in the framework of unified approximations) picture of the NMR absorption in the magnet under consideration. Both local NMR characteristics (resonance frequency, line broadening, enhancement coefficient) and integral characteristics (resultant shape of the absorption line with its specific features) have been calculated. The effective Hamiltonian of the Suhl-Nakamura interaction of nuclear spins through spin waves has been constructed. The second moment and the local broadening of the line of the NMR absorption caused by this interaction have been calculated. The role of the basic local inhomogeneities in the formation of the integral line of the NMR absorption has been analyzed. The opportunities for the experimental NMR investigations in magnets with a chiral spin structure are discussed.

  17. INTRINSIC DOSIMETRY OF GLASS CONTAINERS USED TO TRANSPORT NUCLEAR MATERIALS: Potential Implications to the Field of Nuclear Forensics

    SciTech Connect

    Schwantes, Jon M.; Miller, Steven D.; Piper, Roman K.; Murphy, Mark K.; Amonette, James E.; Bonde, Steven E.; Duckworth, Douglas C.

    2008-09-15

    Thermoluminescence (TL) and Electron Paramagnetic Resonance (EPR) dosimetry were used to measure dose effects in borosilicate glass with time, from 10 minutes to ~60 days following exposure to a dose of up to 10,000 Rad. TL and EPR results were consistent and performed similarly, with both techniques capable of achieving an estimated limit of detection of between 50-100 Rad. Three peaks were identified in the TL glow curve at roughly 110oC, 205oC, and 225oC. The intensity of the 205oC peak was the dominant peak over the time period of this study. The stability of all of the peaks with time since irradiation increased with their corresponding temperature and little or no variation was observed in the glow curve response to a specified total dose attained at different dose rates. The intensity of the 205oC peak decreased logarithmically with time regardless of total dose. Based upon a conservative limit of detection of 330 Rad, a 10,000 Rad dose would still be detected 2.7E3 years after exposure. This paper introduces the concept of intrinsic dosimetry, the consideration of a measured dose received to container walls in concert with the physical characteristics of the radioactive material contained inside those walls, as a method for gathering rather unique pathway information about the history of that sample. Three hypothetical scenarios are presented to introduce this method and to illustrate how intrinsic dosimetry might benefit the fields of nuclear forensics and waste management.

  18. Day after midnight: the effects of nuclear war

    SciTech Connect

    Riordan, M.

    1982-01-01

    This book is an important contribution to the nuclear-weapons debate. Based on a widely circulated OTA report, The Effects of Nuclear War, it depicts in graphic detail the likely social and economic effects of nuclear war on both the United States and the Soviet Union. The book does not try to assess the probability that nuclear conflict, once initiated, would escalate into an all-out war. Rather, it examines four militarily plausible nuclear-attack scenarios ranging from single-weapons detonations to all-out, massive attacks. The one consistent conclusion in all cases is that nuclear war would be an unmitigated catastrophe unlike anything the world has ever experienced. The inherent uncertainties in these analyses, including the possibility of unbridled escalation, are tremendous. Thus, the total extinction of humanity cannot be completely ruled out. 60 references, 16 figures, 6 tables.

  19. Field effect memory alloy heat engine

    SciTech Connect

    Johnson, A.D.; Kirkpatrick, P.F.

    1981-08-04

    A heat engine employing a memory alloy and a force field such as gravity for converting heat energy into mechanical work is disclosed. Field effect elements are mounted on the distal ends of flexible spokes which in turn are mounted about a hub to form a rotating wheel. The memory alloy is in the form of a helix disposed about the circumference of the wheel and interconnecting the ends of adjacent spoke pairs. Heat is transferred to segments of the memory alloy on one side of the wheel so that the segments deform toward their memory shape and deflect the associated spokes toward each other. Heat is transferred away from the memory alloy segments on the opposite side so that the segments deform toward their trained shape and permit the spokes to flex apart. The concentration of field effect elements on the first side of the wheel is greater than the concentration on the other side so that the resultant force created by a remote field acts as a torque for rotating the wheel.

  20. Review of radiation effects in solid-nuclear-waste forms

    SciTech Connect

    Weber, W.J.

    1981-09-01

    Radiation effects on the stability of high-level nuclear waste (HLW) forms are an important consideration in the development of technology to immobilize high-level radioactive waste because such effects may significantly affect the containment of the radioactive waste. Since the required containment times are long (10/sup 3/ to 10/sup 6/ years), an understanding of the long-term cumulative effects of radiation damage on the waste forms is essential. Radiation damage of nuclear waste forms can result in changes in volume, leach rate, stored energy, structure/microstructure, and mechanical properties. Any one or combination of these changes might significantly affect the long-term stability of the nuclear waste forms. This report defines the general radiation damage problem in nuclear waste forms, describes the simulation techniques currently available for accelerated testing of nuclear waste forms, and reviews the available data on radiation effects in both glass and ceramic (primarily crystalline) waste forms. 76 references.

  1. Mixed-radiation-field dosimetry utilizing Nuclear Quadrupole Resonance

    SciTech Connect

    Hintenlang, D.E.; Jamil, K.; Iselin, L.H.

    1992-01-01

    Radiation effects on urea, thiourea, guanidine carbonate and guanine sulfate were evaluated for both photon and neutron irradiations. Hydration of these materials typically provides a greatly increased sensitivity to both forms of radiation exposure, although not all materials lend themselves to this treatment without changing the chemical structure of the compound. Urea was found to be the most stable hydrated compound and provides the best sensitivity for quantifying radiation effects using NQR techniques. Urea permits a straight-forward quantification of each of the important parameters of the observed NQR signal, the FID. Several advanced data analysis methods were developed to assist in quantifying NQR spectra, both from urea and materials having more complex molecular structures, such as thiourea and guanidine sulfate. Unfortunately, these analysis techniques are frequently quite time consuming for the complex NQR spectra that result from some of these materials. The simpler analysis afforded by urea has therefore made it the prime candidate for an NQR dosimetry material. The moderate sensitivity of hydrated urea to photon irradiation does not permit this material to achieve the levels of performance required for a personnel dosimeter. It does, however, demonstrate acceptable sensitivity over dose ranges where it could provide a good biological dosimeter for several areas of radiation processing. The demonstrated photon sensitivity could permit hydrated urea to be used in applications such as food irradiation dosimetry. This material also exhibits a good sensitivity to neutron irradiation. The precise correlation between neutron exposure and the parameters of the resulting NQR spectra are currently being developed.

  2. Novel QCD effects in nuclear collisions

    SciTech Connect

    Brodsky, S.J.

    1991-12-01

    Heavy ion collisions can provide a novel environment for testing fundamental dynamical processes in QCD, including minijet formation and interactions, formation zone phenomena, color filtering, coherent co-mover interactions, and new higher twist mechanisms which could account for the observed excess production and anomalous nuclear target dependence of heavy flavor production. The possibility of using light-cone thermodynamics and a corresponding covariant temperature to describe the QCD phases of the nuclear fragmentation region is also briefly discussed.

  3. Nuclear Effects in Generators: the Path Forward

    SciTech Connect

    Mosel, Ulrich

    2011-11-23

    The extraction of neutrino oscillation parameters requires the determination of the neutrino energy from observations of the hadronic final state. The use of nuclear targets then requires the use of event generators to isolate the interesting elementary processes and to take experimental acceptances into account. In this talk I briefly summarize the history of event generators and their use in nuclear physics, talk briefly about the generators used in the neutrino community and then discuss future necessary developments.

  4. Radiative reactions in halo effective field theory

    NASA Astrophysics Data System (ADS)

    Rupak, Gautam

    2016-03-01

    In this article we review the recent progress in radiative reaction calculations in halo effective field theory. We look at radiative capture and breakup processes that involve a halo nucleus with a single valence neutron or proton. Looking at 7Li(n,γ) 8Li,14C(n,γ)15C and related reactions, the dominant source of theoretical uncertainty in s- and p-wave halo nuclei reaction calculations is quantified in a model-independent framework. The analysis for neutron halos is extended to proton halo systems. The effective field theory results quantify which observable parameters of the strong interaction at low energy need to be determined more precisely for accurate cross-section calculations.

  5. Antiferromagnetic Spin Wave Field-Effect Transistor.

    PubMed

    Cheng, Ran; Daniels, Matthew W; Zhu, Jian-Gang; Xiao, Di

    2016-01-01

    In a collinear antiferromagnet with easy-axis anisotropy, symmetry dictates that the spin wave modes must be doubly degenerate. Theses two modes, distinguished by their opposite polarization and available only in antiferromagnets, give rise to a novel degree of freedom to encode and process information. We show that the spin wave polarization can be manipulated by an electric field induced Dzyaloshinskii-Moriya interaction and magnetic anisotropy. We propose a prototype spin wave field-effect transistor which realizes a gate-tunable magnonic analog of the Faraday effect, and demonstrate its application in THz signal modulation. Our findings open up the exciting possibility of digital data processing utilizing antiferromagnetic spin waves and enable the direct projection of optical computing concepts onto the mesoscopic scale. PMID:27048928

  6. Antiferromagnetic Spin Wave Field-Effect Transistor

    NASA Astrophysics Data System (ADS)

    Cheng, Ran; Daniels, Matthew W.; Zhu, Jian-Gang; Xiao, Di

    2016-04-01

    In a collinear antiferromagnet with easy-axis anisotropy, symmetry dictates that the spin wave modes must be doubly degenerate. Theses two modes, distinguished by their opposite polarization and available only in antiferromagnets, give rise to a novel degree of freedom to encode and process information. We show that the spin wave polarization can be manipulated by an electric field induced Dzyaloshinskii-Moriya interaction and magnetic anisotropy. We propose a prototype spin wave field-effect transistor which realizes a gate-tunable magnonic analog of the Faraday effect, and demonstrate its application in THz signal modulation. Our findings open up the exciting possibility of digital data processing utilizing antiferromagnetic spin waves and enable the direct projection of optical computing concepts onto the mesoscopic scale.

  7. Antiferromagnetic Spin Wave Field-Effect Transistor

    PubMed Central

    Cheng, Ran; Daniels, Matthew W.; Zhu, Jian-Gang; Xiao, Di

    2016-01-01

    In a collinear antiferromagnet with easy-axis anisotropy, symmetry dictates that the spin wave modes must be doubly degenerate. Theses two modes, distinguished by their opposite polarization and available only in antiferromagnets, give rise to a novel degree of freedom to encode and process information. We show that the spin wave polarization can be manipulated by an electric field induced Dzyaloshinskii-Moriya interaction and magnetic anisotropy. We propose a prototype spin wave field-effect transistor which realizes a gate-tunable magnonic analog of the Faraday effect, and demonstrate its application in THz signal modulation. Our findings open up the exciting possibility of digital data processing utilizing antiferromagnetic spin waves and enable the direct projection of optical computing concepts onto the mesoscopic scale. PMID:27048928

  8. A silicon nanocrystal tunnel field effect transistor

    SciTech Connect

    Harvey-Collard, Patrick; Drouin, Dominique; Pioro-Ladrière, Michel

    2014-05-12

    In this work, we demonstrate a silicon nanocrystal Field Effect Transistor (ncFET). Its operation is similar to that of a Tunnelling Field Effect Transistor (TFET) with two barriers in series. The tunnelling barriers are fabricated in very thin silicon dioxide and the channel in intrinsic polycrystalline silicon. The absence of doping eliminates the problem of achieving sharp doping profiles at the junctions, which has proven a challenge for large-scale integration and, in principle, allows scaling down the atomic level. The demonstrated ncFET features a 10{sup 4} on/off current ratio at room temperature, a low 30 pA/μm leakage current at a 0.5 V bias, an on-state current on a par with typical all-Si TFETs and bipolar operation with high symmetry. Quantum dot transport spectroscopy is used to assess the band structure and energy levels of the silicon island.

  9. Antiferromagnetic Spin Wave Field-Effect Transistor

    DOE PAGESBeta

    Cheng, Ran; Daniels, Matthew W.; Zhu, Jian-Gang; Xiao, Di

    2016-04-06

    In a collinear antiferromagnet with easy-axis anisotropy, symmetry dictates that the spin wave modes must be doubly degenerate. Theses two modes, distinguished by their opposite polarization and available only in antiferromagnets, give rise to a novel degree of freedom to encode and process information. We show that the spin wave polarization can be manipulated by an electric field induced Dzyaloshinskii-Moriya interaction and magnetic anisotropy. We propose a prototype spin wave field effect transistor which realizes a gate-tunable magnonic analog of the Faraday effect, and demonstrate its application in THz signal modulation. In conclusion, our findings open up the exciting possibilitymore » of digital data processing utilizing antiferromagnetic spin waves and enable the direct projection of optical computing concepts onto the mesoscopic scale.« less

  10. Numerical design of outer diameter remote field eddy current probe for the inspection of nuclear fuel rod

    NASA Astrophysics Data System (ADS)

    Shin, Young-Kil; Sun, Yushi

    2001-04-01

    In this paper, an encircling outer diameter (OD) remote field eddy current (RFEC) probe is proposed to inspect the nuclear fuel rod. To force the electromagnetic energy from exciter coil to penetrate into the rod, shielding by laminations of iron is applied outside the exciter coil. The operating frequency and effects of shielding are studied by the finite element analysis and modeling results show the existence of RFEC effects. Based on these results, the location for an encircling OD sensor coil is decided. However, predicted signals do not clearly show defect indications when the sensor passes a defect and exhibit certain symptoms that the fields from the exciter directly affect the sensor signal. To prevent direct contact with exciter fields, the sensor coil is also shielded. This shielding of sensor coil dramatically improves signal characteristics. The resulting signals have very similar characteristics to those of inner diameter RFEC signals and show almost equal sensitivity to inner diameter and outer diameter defects.

  11. Evaluation of near-field earthquake effects

    SciTech Connect

    Shrivastava, H.P.

    1994-11-01

    Structures and equipment, which are qualified for the design basis earthquake (DBE) and have anchorage designed for the DBE loading, do not require an evaluation of the near-field earthquake (NFE) effects. However, safety class 1 acceleration sensitive equipment such as electrical relays must be evaluated for both NFE and DBE since they are known to malfunction when excited by high frequency seismic motions.

  12. Capture Reactions with Halo Effective Field Theory

    NASA Astrophysics Data System (ADS)

    Higa, R.

    2015-12-01

    Loosely bound nuclei far from the stability region emerge as a quantum phenomenon with many universal properties. The connection between these properties and the underlying symmetries can be best explored with halo/cluster EFT, an effective field theory where the softness of the binding momentum and the hardness of the core(s) form the expansion parameter of a given perturbative approach. In the following I highlight a particular application where these ideas are being tested, namely capture reactions.

  13. Halo Effective Field Theory of 6He

    NASA Astrophysics Data System (ADS)

    Thapaliya, Arbin; Ji, Chen; Phillips, Daniel

    2016-03-01

    6He has a cluster structure with a tight 4He (α) core surrounded by two loosely bound neutrons (n) making it a halo nucleus. The leading-order (LO) Halo Effective Field Theory (EFT) [1, 2] calculations using momentum-space Faddeev equations pertinent to a bound 6He were carried out in [3]. In this work, we investigate 6He up to next-to-leading order (NLO) within Halo EFT.

  14. Effects of acidic precipitation on field crops

    SciTech Connect

    Evans, L.S.; Hendrey, G.R.; Lewin, K.F.; Gmur, N.F.

    1982-02-01

    The effects of acid rain on yields of field-grown soybeans has been investigated. Plants exposed to simulated rainfalls of pH 4.1, 3,3 and 2.7 had decreased seed yields of 10.6, 16.8 and 23.9% below yields of plants exposed to simulated rainfalls of pH 5.6. (ACR)

  15. Pressure Sensitive Insulated Gate Field Effect Transistor

    NASA Astrophysics Data System (ADS)

    Suminto, James Tjan-Meng

    A pressure sensitive insulated gate field effect transistor has been developed. The device is an elevated gate field-effect-transistor. It consists of a p-type silicon substrate in which two n^+ region, the source and drain, are formed. The gate electrode is a metal film sandwiched in an insulated micro-diaphragm resembling a pill-box which covers the gate oxide, drain, and source. The space between the gate electrode and the oxide is vacuum or an air-gap. When pressure is applied on the diaphragm it deflects and causes a change in the gate capacitance, and thus modulates the conductance of the channel between source and drain. A general theory dealing with the characteristic of this pressure sensitive insulated gate field effect transistor has been derived, and the device fabricated. The fabrication process utilizes the standard integrated circuit fabrication method. It features a batch fabrication of field effect devices followed by the batch fabrication of the deposited diaphragm on top of each field effect device. The keys steps of the diaphragm fabrication are the formation of spacer layer, formation of the diaphragm layer, and the subsequent removal of the spacer layer. The chip size of the device is 600 μm x 1050 mum. The diaphragm size is 200 μm x 200 mum. Characterization of the device has been performed. The current-voltage characteristics with pressure as parameters have been demonstrated and the current-pressure transfer curves obtained. They show non-linear characteristics as those of conventional capacitive pressure sensors. The linearity of threshold voltage versus pressure transfer curves has been demonstrated. The temperature effect on the device performances has been tested. The temperature coefficient of threshold voltage, rather than the electron mobility, has dominated the temperature coefficient of the device. Two temperature compensation schemes have been tested: one method is by connecting two identical PSIGFET in a differential amplifier

  16. Pion condensation in a relativistic field theory consistent with bulk properties of nuclear matter

    SciTech Connect

    Banerjee, B.; Glendenning, N. K.; Gyulassy, M.

    1981-05-01

    Pion condensation is investigated in a self-consistent. relativistic mean field theory that is constrained to reproduce the bulk properties of nuclear matter. This constraint and self-consistency provide stringent constraints on the existence and energy of the condensate.

  17. An effect of nuclear electric quadrupole moments in thermonuclear fusion plasmas

    NASA Technical Reports Server (NTRS)

    De, B. R.; Srnka, L. J.

    1978-01-01

    Consideration of the nuclear electric quadrupole terms in the expression for the fusion Coulomb barrier suggests that this electrostatic barrier may be substantially modified from that calculated under the usual plasma assumption that the nuclei are electric monopoles. This effect is a result of the nonspherical potential shape and the spatial quantization of the nuclear spins of the fully stripped ions in the presence of a magnetic field. For monopole-quadrupole fuel cycles like p-B-11, the fusion cross-section may be substantially increased at low energies if the protons are injected at a small angle relative to the confining magnetic field.

  18. Microwave field distribution in a magic angle spinning dynamic nuclear polarization NMR probe

    NASA Astrophysics Data System (ADS)

    Nanni, Emilio A.; Barnes, Alexander B.; Matsuki, Yoh; Woskov, Paul P.; Corzilius, Björn; Griffin, Robert G.; Temkin, Richard J.

    2011-05-01

    We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B 1 S) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4 mm diameter sapphire rotor containing the sample. The predicted average B 1 S field is 13 μT/W 1/2, where S denotes the electron spin. For a routinely achievable input power of 5 W the corresponding value is γSB 1 S = 0.84 MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement ( ɛ) vs. ω1 S/(2 π) for a sample of 13C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment.

  19. Microwave field distribution in a magic angle spinning dynamic nuclear polarization NMR probe.

    PubMed

    Nanni, Emilio A; Barnes, Alexander B; Matsuki, Yoh; Woskov, Paul P; Corzilius, Björn; Griffin, Robert G; Temkin, Richard J

    2011-05-01

    We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B(1S)) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4mm diameter sapphire rotor containing the sample. The predicted average B(1S) field is 13μT/W(1/2), where S denotes the electron spin. For a routinely achievable input power of 5W the corresponding value is γ(S)B(1S)=0.84MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (ϵ) vs. ω(1S)/(2π) for a sample of (13)C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment. PMID:21382733

  20. Microwave Field Distribution in a Magic Angle Spinning Dynamic Nuclear Polarization NMR Probe

    PubMed Central

    Nanni, Emilio A.; Barnes, Alexander B.; Matsuki, Yoh; Woskov, Paul P.; Corzilius, Björn; Griffin, Robert G.; Temkin, Richard J.

    2011-01-01

    We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B1S) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4 mm diameter sapphire rotor containing the sample. The predicted average B1S field is 13µT/W1/2, where S denotes the electron spin. For a routinely achievable input power of 5 W the corresponding value is γ SB1S = 0.84 MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (ε) vs. ω1S/(2π) for a sample of 13C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment. PMID:21382733

  1. Applied-field MPD thruster geometry effects

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.

    1991-01-01

    Eight MPD thruster configurations were used to study the effects of applied-field strength, propellant, and facility pressure on thruster performance. Vacuum facility background pressures higher than about 0.12 Pa were found to significantly influence thruster performance and electrode power deposition. Thrust efficiency and specific impulse increased monotonically with increasing applied field strength. Both cathode and anode radii fundamentally influenced the efficiency-specific impulse relationship, while their lengths influenced only the magnitude of the applied magnetic field required to reach a given performance level. At a given specific impulse, large electrode radii result in lower efficiencies for the operating conditions studied. For all test conditions, anode power deposition was the largest efficiency loss, and represented between 50 percent and 80 percent of the input power. The fraction of the input power deposited into the anode decreased with increasing applied field and anode radius. The highest performance measured, 20 percent efficiency at 3700 seconds specific impulse, was obtained using hydrogen propellant.

  2. Direct extraction of nuclear effects in quasielastic scattering on carbon

    NASA Astrophysics Data System (ADS)

    Wilkinson, Callum; McFarland, Kevin S.

    2016-07-01

    Nuclear effects on neutrino reactions are expected to be a significant complication in current and future neutrino oscillation experiments seeking precision measurements of neutrino flavor transitions. Calculations of these nuclear effects are hampered by a lack of experimental data comparing neutrino reactions on free nucleons to neutrino reactions on nuclei. We present results from a novel technique that compares neutrino and antineutrino charged current quasielastic scattering on hydrocarbons to extract a cross section ratio of antineutrino charged current elastic reactions on free protons to charged current quasielastic reactions on the protons bound in a carbon nucleus. This measurement of nuclear effects is compared to models.

  3. Tantalum Disulfide Ionic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Yu, Yijun; Yang, Fangyuan; Lu, Xiu Fang; Yan, Ya Jun; Cho, Y. H.; Ma, Liguo; Niu, Xiaohai; Kim, Sejoong; Son, Yong-Woo; Feng, Donglai; Li, Shiyan; Cheong, Sang-Wook; Chen, Xian Hui; Zhang, Yuanbo

    2015-03-01

    The ability to tune material properties using gate electric field is at the heart of the modern electronic technology. Electrolyte gating has recently emerged as an important technique to reach extremely high surface charge carrier concentration in a variety of materials through the formation of electric double layer (EDL) at the sample surface. Here we demonstrate a new mechanism of electrolyte gating that modulates the volumetric carrier density by gate-controlled intercalation in layered materials. We fabricate field-effect transistors (referred to as ionic field-effect transistor, iFET) based on transition metal dichalcogenides 1T-TaS2 and 2H-TaS2. The unprecedented large doping induces dramatic changes in the transport properties of the sample, including CDW phase transitions, superconductivity and metal-to-insulator transitions. The controllable and reversible intercalation of different ion spices into layered materials opens up new possibilities in searching for novel states of matter in the extreme charge-carrier-concentration limit.

  4. Surface layer effect on nuclear deformation energy

    NASA Astrophysics Data System (ADS)

    Kolomietz, V. M.; Sanzhur, A. I.; Reznychenko, B. V.

    2016-03-01

    In this paper, we apply the direct variational method to derive the nuclear deformation energy. The extended Thomas-Fermi approximation (ETFA) for the energy functional with Skyrme forces is used. We study the influence of the finite surface layer of the nuclear density profile function on the formation of the fission barrier and the scission configuration. Comparison of the variational approach with the traditional liquid drop model (LDM) is presented. We show the sensitivity of the numerical results to the surface diffuseness parameter.

  5. Transition-Selective Pulses in Zero-Field Nuclear Magnetic Resonance.

    PubMed

    Sjolander, Tobias F; Tayler, Michael C D; King, Jonathan P; Budker, Dmitry; Pines, Alexander

    2016-06-30

    We use low-amplitude, ultralow frequency pulses to drive nuclear spin transitions in zero and ultralow magnetic fields. In analogy to high-field NMR, a range of sophisticated experiments becomes available as these allow narrow-band excitation. As a first demonstration, pulses with excitation bandwidths 0.5-5 Hz are used for population redistribution, selective excitation, and coherence filtration. These methods are helpful when interpreting zero- and ultralow-field NMR spectra that contain a large number of transitions. PMID:27243376

  6. Field-effect P-N junction

    DOEpatents

    Regan, William; Zettl, Alexander

    2015-05-05

    This disclosure provides systems, methods, and apparatus related to field-effect p-n junctions. In one aspect, a device includes an ohmic contact, a semiconductor layer disposed on the ohmic contact, at least one rectifying contact disposed on the semiconductor layer, a gate including a layer disposed on the at least one rectifying contact and the semiconductor layer and a gate contact disposed on the layer. A lateral width of the rectifying contact is less than a semiconductor depletion width of the semiconductor layer. The gate contact is electrically connected to the ohmic contact to create a self-gating feedback loop that is configured to maintain a gate electric field of the gate.

  7. NMR-based structural biology enhanced by dynamic nuclear polarization at high magnetic field.

    PubMed

    Koers, Eline J; van der Cruijsen, Elwin A W; Rosay, Melanie; Weingarth, Markus; Prokofyev, Alexander; Sauvée, Claire; Ouari, Olivier; van der Zwan, Johan; Pongs, Olaf; Tordo, Paul; Maas, Werner E; Baldus, Marc

    2014-11-01

    Dynamic nuclear polarization (DNP) has become a powerful method to enhance spectroscopic sensitivity in the context of magnetic resonance imaging and nuclear magnetic resonance spectroscopy. We show that, compared to DNP at lower field (400 MHz/263 GHz), high field DNP (800 MHz/527 GHz) can significantly enhance spectral resolution and allows exploitation of the paramagnetic relaxation properties of DNP polarizing agents as direct structural probes under magic angle spinning conditions. Applied to a membrane-embedded K(+) channel, this approach allowed us to refine the membrane-embedded channel structure and revealed conformational substates that are present during two different stages of the channel gating cycle. High-field DNP thus offers atomic insight into the role of molecular plasticity during the course of biomolecular function in a complex cellular environment. PMID:25284462

  8. Effective field theory analysis of Higgs naturalness

    SciTech Connect

    Bar-Shalom, Shaouly; Soni, Amarjit; Wudka, Jose

    2015-07-20

    Assuming the presence of physics beyond the Standard Model ( SM) with a characteristic scale M ~ O (10) TeV, we investigate the naturalness of the Higgs sector at scales below M using an effective field theory (EFT) approach. We obtain the leading 1 -loop EFT contributions to the Higgs mass with a Wilsonian-like hard cutoff, and determine t he constraints on the corresponding operator coefficients for these effects to alleviate the little hierarchy problem up to the scale of the effective action Λ < M , a condition we denote by “EFT-naturalness”. We also determine the types of physics that can lead to EFT-naturalness and show that these types of new physics are best probed in vector-boson and multiple-Higgs production. The current experimental constraints on these coefficients are also discussed.

  9. Contact electrification field-effect transistor.

    PubMed

    Zhang, Chi; Tang, Wei; Zhang, Limin; Han, Changbao; Wang, Zhong Lin

    2014-08-26

    Utilizing the coupled metal oxide semiconductor field-effect transistor and triboelectric nanogenerator, we demonstrate an external force triggered/controlled contact electrification field-effect transistor (CE-FET), in which an electrostatic potential across the gate and source is created by a vertical contact electrification between the gate material and a “foreign” object, and the carrier transport between drain and source can be tuned/controlled by the contact-induced electrostatic potential instead of the traditional gate voltage. With the two contacted frictional layers vertically separated by 80 μm, the drain current is decreased from 13.4 to 1.9 μA in depletion mode and increased from 2.4 to 12.1 μA in enhancement mode at a drain voltage of 5 V. Compared with the piezotronic devices that are controlled by the strain-induced piezoelectric polarization charged at an interface/junction, the CE-FET has greatly expanded the sensing range and choices of materials in conjunction with semiconductors. The CE-FET is likely to have important applications in sensors, human–silicon technology interfacing, MEMS, nanorobotics, and active flexible electronics. Based on the basic principle of the CE-FET, a field of tribotronics is proposed for devices fabricated using the electrostatic potential created by triboelectrification as a “gate” voltage to tune/control charge carrier transport in conventional semiconductor devices. By the three-way coupling among triboelectricity, semiconductor, and photoexcitation, plenty of potentially important research fields are expected to be explored in the near future. PMID:25119657

  10. Measurement of the 14N nuclear quadrupole resonance frequencies by the solid effect

    NASA Astrophysics Data System (ADS)

    Seliger, J.; Žagar, V.

    2008-07-01

    1H- 14N nuclear quadrupole double resonance using magnetic field cycling between high and low magnetic field and solid effect in the low magnetic field is analyzed in details. The transition probabilities per unit time for the solid-effect transitions are calculated. The double resonance spectra are calculated in the limiting cases of fast and slow nitrogen spin-lattice relaxation. The double resonance spectra are measured in histamine and quinolinic acid. The experimental spectra are analyzed and the 14N NQR frequencies are determined.

  11. Efficient dynamic nuclear polarization of phosphorus in silicon in strong magnetic fields and at low temperatures

    NASA Astrophysics Data System (ADS)

    Järvinen, J.; Ahokas, J.; Sheludyakov, S.; Vainio, O.; Lehtonen, L.; Vasiliev, S.; Zvezdov, D.; Fujii, Y.; Mitsudo, S.; Mizusaki, T.; Gwak, M.; Lee, SangGap; Lee, Soonchil; Vlasenko, L.

    2014-12-01

    Efficient manipulation of nuclear spins is important for utilizing them as qubits for quantum computing. In this work we report record high polarizations of 31P and 29Si nuclear spins in P-doped silicon in a strong magnetic field (4.6 T) and at temperatures below 1 K. We reached 31P nuclear polarization values exceeding 98 % after 20 min of pumping the high-field electron spin resonance (ESR) line with a very small microwave power of 0.4 μ W . We evaluate that the ratio of the hyperfine-state populations increases by three orders of magnitude after 2 hours of pumping, and an extremely pure nuclear spin state can be created, with less than 0.01 ppb impurities. A negative dynamic nuclear polarization has been observed by pumping the low-field ESR line of 31P followed by the flip-flip cross relaxation, the transition which is fully forbidden for isolated donors. We estimate that while pumping the ESR transitions of 31P also the nuclei of 29Si get polarized, and polarization exceeding 60 % has been obtained. We performed measurements of relaxation rates of flip-flop and flip-flip transitions which turned out to be nearly temperature independent. Temperature dependence of the 31P nuclear relaxation was studied down to 0.75 K, below which the relaxation time became too long to be measured. We found that the polarization evolution under pumping and during relaxation deviates substantially from a simple exponential function of time. We suggest that the nonexponential polarization dynamics of 31P donors is mediated by the orientation of 29Si nuclei, which affect the transition probabilities of the forbidden cross-relaxation processes.

  12. 1987 Annual Conference on Nuclear and Space Radiation Effects, Snowmass Village, CO, July 28-31, 1987, Proceedings

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Various papers on nuclear and space radiation effects are presented. The general topics addressed include: basic mechanisms of radiation effects, single-event phenomena, temperature and field effects, modeling and characterization of radiation effects, IC radiation effects and hardening, and EMP/SGEMP/IEMP phenomena. Also considered are: dosimetry/energy-dependent effects, sensors in and for radiation environments, spacecraft charging and space radiation effects, radiation effects and devices, radiation effects on isolation technologies, and hardness assurance and testing techniques.

  13. Ionospheric Effects of Underground Nuclear Explosions

    NASA Astrophysics Data System (ADS)

    Park, J.; von Frese, R. R.; G-Brzezinska, D. A.; Morton, Y.

    2010-12-01

    Telemetry from the Russian INTERCOSMOS 24 satellite recorded ELF and VLF electromagnetic disturbances in the outer ionosphere from an underground nuclear explosion that was detonated at Novaya Zemlya Island on 24 October 1994. The IC24 satellite observations were obtained at about 900 km altitude within a few degrees of ground zero. The disturbances were interpreted for magnetohydrodynamic excitation of the ionosphere’s E layer by the acoustic wave. Electrons are accelerated along the magnetic force lines to amplify longitudinal currents and magnetic disturbances that may be measured by magnetometers at ground-based observatories and on-board satellites. The underground nuclear test near P’unggye, North Korea on 25 May 2009 provides a further significant opportunity for studying the utility of ionospheric disturbances for characterizing ground zero. Of the seismic, infrasound, hydroacoustic, and radionuclide detection elements of the International Monitoring System (IMS) established by the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), only the first two elements detected this event. However, the event also appears to have been recorded as a direct traveling ionospheric disturbance (TID) in the slant total electron content (TEC) observations derived from a network of the Global Navigation Satellite System (GNSS) measurements. The TID was observed to distances of at least 600 km from the explosion site propagating with a speed of about 281m/s. Thus, the global distributions and temporal variations of the TEC, may provide important information to help detect and characterize clandestine underground nuclear explosions.

  14. The Italian Activities in the Field of Nuclear Waste Management - 12439

    SciTech Connect

    Giorgiantoni, Giorgio; Marzo, Giuseppe A.; Sepielli, Massimo

    2012-07-01

    The Italian situation in the field of nuclear waste management is characterized by a relative small quantity of wastes, as a consequence of the giving up of energy production by nuclear generation in 1986. Notwithstanding this situation, Italy is a unique case study since the country needs to undertake the final decommissioning of four shut-down NPPs (size 100-200 MWe), each one different from the others. Therefore all the regulatory, technical, and financial actions are needed in the same way as if there was actual nuclear generation. Furthermore, the various non-power generating applications of nuclear energy still require management, a legal framework, a regulatory body, an industrial structure, and technical know-how. Notwithstanding the absence of energy production from nuclear sources, the country has the burden of radioactive waste management from the previous nuclear operations, which obliges it to implement at first a robust legislative framework, then to explore all the complex procedures to achieve the localization of the national interim storage facility, not excluding the chance to have a European regional facility for geologic disposal, under the clauses of the Council Directive of 19 July 2011 'Establishing a Community Framework for the Responsible and Safe Management of Radioactive Waste'. Then, as far as industrial, medical and R and D aspects, the improvement of the legislative picture, the creation of a regulatory body, is a good start for the future, to achieve the best efficiency of the Italian system. (authors)

  15. Effective field theory for quantum liquid in dwarf stars

    SciTech Connect

    Gabadadze, Gregory; Rosen, Rachel A. E-mail: rarosen@physik.su.se

    2010-04-01

    An effective field theory approach is used to describe quantum matter at greater-than-atomic but less-than-nuclear densities which are encountered in white dwarf stars. We focus on the density and temperature regime for which charged spin-0 nuclei form an interacting charged Bose-Einstein condensate, while the neutralizing electrons form a degenerate fermi gas. After a brief introductory review, we summarize distinctive properties of the charged condensate, such as a mass gap in the bosonic sector as well as gapless fermionic excitations. Charged impurities placed in the condensate are screened with great efficiency, greater than in an equivalent uncondensed plasma. We discuss a generalization of the Friedel potential which takes into account bosonic collective excitations in addition to the fermionic excitations. We argue that the charged condensate could exist in helium-core white dwarf stars and discuss the evolution of these dwarfs. Condensation would lead to a significantly faster rate of cooling than that of carbon- or oxygen-core dwarfs with crystallized cores. This prediction can be tested observationally: signatures of charged condensation may have already been seen in the recently discovered sequence of helium-core dwarfs in the nearby globular cluster NGC 6397. Sufficiently strong magnetic fields can penetrate the condensate within Abrikosov-like vortices. We find approximate analytic vortex solutions and calculate the values of the lower and upper critical magnetic fields at which vortices are formed and destroyed respectively. The lower critical field is within the range of fields observed in white dwarfs, but tends toward the higher end of this interval. This suggests that for a significant fraction of helium-core dwarfs, magnetic fields are entirely expelled within the core.

  16. Recursive polarization of nuclear spins in diamond at arbitrary magnetic fields

    SciTech Connect

    Pagliero, Daniela; Laraoui, Abdelghani; Henshaw, Jacob D.; Meriles, Carlos A.

    2014-12-15

    We introduce an alternate route to dynamically polarize the nuclear spin host of nitrogen-vacancy (NV) centers in diamond. Our approach articulates optical, microwave, and radio-frequency pulses to recursively transfer spin polarization from the NV electronic spin. Using two complementary variants of the same underlying principle, we demonstrate nitrogen nuclear spin initialization approaching 80% at room temperature both in ensemble and single NV centers. Unlike existing schemes, our approach does not rely on level anti-crossings and is thus applicable at arbitrary magnetic fields. This versatility should prove useful in applications ranging from nanoscale metrology to sensitivity-enhanced NMR.

  17. Guidance for Deployment of Mobile Technologies for Nuclear Power Plant Field Workers

    SciTech Connect

    Heather D. Medema; Ronald K. Farris

    2012-09-01

    This report is a guidance document prepared for the benefit of commercial nuclear power plants’ (NPPs) supporting organizations and personnel who are considering or undertaking deployment of mobile technology for the purpose of improving human performance and plant status control (PSC) for field workers in an NPP setting. This document especially is directed at NPP business managers, Electric Power Research Institute, Institute of Nuclear Power Operations, and other non-Information Technology personnel. This information is not intended to replace basic project management practices or reiterate these processes, but is to support decision-making, planning, and preparation of a business case.

  18. Alpha particles in effective field theory

    SciTech Connect

    Caniu, C.

    2014-11-11

    Using an effective field theory for alpha (α) particles at non-relativistic energies, we calculate the strong scattering amplitude modified by Coulomb corrections for a system of two αs. For the strong interaction, we consider a momentum-dependent interaction which, in contrast to an energy dependent interaction alone [1], could be more useful in extending the theory to systems with more than two α particles. We will present preliminary results of our EFT calculations for systems with two alpha particles.

  19. Oxidation and crystal field effects in uranium

    SciTech Connect

    Tobin, J. G.; Booth, C. H.; Shuh, D. K.; van der Laan, G.; Sokaras, D.; Weng, T. -C.; Yu, S. W.; Bagus, P. S.; Tyliszczak, T.; Nordlund, D.

    2015-07-06

    An extensive investigation of oxidation in uranium has been pursued. This includes the utilization of soft x-ray absorption spectroscopy, hard x-ray absorption near-edge structure, resonant (hard) x-ray emission spectroscopy, cluster calculations, and a branching ratio analysis founded on atomic theory. The samples utilized were uranium dioxide (UO2), uranium trioxide (UO3), and uranium tetrafluoride (UF4). As a result, a discussion of the role of non-spherical perturbations, i.e., crystal or ligand field effects, will be presented.

  20. Bayesian parameter estimation for effective field theories

    NASA Astrophysics Data System (ADS)

    Wesolowski, Sarah; Klco, Natalie; Furnstahl, Richard; Phillips, Daniel; Thapilaya, Arbin

    2015-10-01

    We present a procedure based on Bayesian statistics for effective field theory (EFT) parameter estimation from experimental or lattice data. The extraction of low-energy constants (LECs) is guided by physical principles such as naturalness in a quantifiable way and various sources of uncertainty are included by the specification of Bayesian priors. Special issues for EFT parameter estimation are demonstrated using representative model problems, and a set of diagnostics is developed to isolate and resolve these issues. We apply the framework to the extraction of the LECs of the nucleon mass expansion in SU(2) chiral perturbation theory from synthetic lattice data.

  1. Cluster tidal fields: Effects on disk galaxies

    NASA Technical Reports Server (NTRS)

    Valluri, Monica

    1993-01-01

    A variety of observations of galaxies in clusters indicate that the gas in these galaxies is strongly affected by the cluster environment. We present results of a study of the dynamical effects of the mean cluster tidal field on a disk galaxy as it falls into a cluster for the first time on a bound orbit with constant angular momentum (Valluri 1992). The problem is studied in the restricted 3-body framework. The cluster is modelled by a modified Hubble potential and the disk galaxy is modelled as a flattened spheroid.

  2. Hysteresis modeling in graphene field effect transistors

    SciTech Connect

    Winters, M.; Rorsman, N.; Sveinbjörnsson, E. Ö.

    2015-02-21

    Graphene field effect transistors with an Al{sub 2}O{sub 3} gate dielectric are fabricated on H-intercalated bilayer graphene grown on semi-insulating 4H-SiC by chemical vapour deposition. DC measurements of the gate voltage v{sub g} versus the drain current i{sub d} reveal a severe hysteresis of clockwise orientation. A capacitive model is used to derive the relationship between the applied gate voltage and the Fermi energy. The electron transport equations are then used to calculate the drain current for a given applied gate voltage. The hysteresis in measured data is then modeled via a modified Preisach kernel.

  3. Oxidation and crystal field effects in uranium

    NASA Astrophysics Data System (ADS)

    Tobin, J. G.; Yu, S.-W.; Booth, C. H.; Tyliszczak, T.; Shuh, D. K.; van der Laan, G.; Sokaras, D.; Nordlund, D.; Weng, T.-C.; Bagus, P. S.

    2015-07-01

    An extensive investigation of oxidation in uranium has been pursued. This includes the utilization of soft x-ray absorption spectroscopy, hard x-ray absorption near-edge structure, resonant (hard) x-ray emission spectroscopy, cluster calculations, and a branching ratio analysis founded on atomic theory. The samples utilized were uranium dioxide (U O2) , uranium trioxide (U O3) , and uranium tetrafluoride (U F4) . A discussion of the role of nonspherical perturbations, i.e., crystal or ligand field effects, will be presented.

  4. Goal direction and effectiveness, emotional maturity, and nuclear family functioning.

    PubMed

    Klever, Phillip

    2009-07-01

    Differentiation of self, a cornerstone concept in Bowen theory, has a profound influence over time on the functioning of the individual and his or her family unit. This 5-year longitudinal study tested this hypothesis with 50 developing nuclear families. The dimensions of differentiation of self that were examined were goal direction and effectiveness and emotional maturity. A qualitative analysis of participants' goals demonstrated that couples with higher functioning developing nuclear families, when compared with couples with lower functioning families, placed more emphasis on family goals, had more balance between family and personal goals, and pursued more goals over the 5 years. The quantitative analysis supported the hypothesis that goal effectiveness and emotional maturity influenced variation in nuclear family functioning. In addition, couple goal effectiveness and emotional maturity were associated with nuclear family functioning more strongly than individual goal effectiveness and emotional maturity were associated with individual functioning. PMID:19522784

  5. Effect of magnetic field fluctuation on ultra-low field MRI measurements in the unshielded laboratory environment

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Chang, Baolin; Qiu, Longqing; Dong, Hui; Qiu, Yang; Zhang, Yi; Krause, Hans-Joachim; Offenhäusser, Andreas; Xie, Xiaoming

    2015-08-01

    Magnetic field fluctuations in our unshielded urban laboratory can reach hundreds of nT in the noisy daytime and is only a few nT in the quiet midnight. The field fluctuation causes the Larmor frequency fL to drift randomly for several Hz during the unshielded ultra-low field (ULF) nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) measurements, thus seriously spoiling the averaging effect and causing imaging artifacts. By using an active compensation (AC) technique based on the spatial correlation of the low-frequency magnetic field fluctuation, the field fluctuation can be suppressed to tens of nT, which is a moderate situation between the noisy daytime and the quiet midnight. In this paper, the effect of the field fluctuation on ULF MRI measurements was investigated. The 1D and 2D MRI signals of a water phantom were measured using a second-order low-Tc superconducting quantum interference device (SQUID) in three fluctuation cases: severe fluctuation (noisy daytime), moderate fluctuation (daytime with AC) and minute fluctuation (quiet midnight) when different gradient fields were applied. When the active compensation is applied or when the frequency encoding gradient field Gx reaches a sufficiently strong value in our measurements, the image artifacts become invisible in all three fluctuation cases. Therefore it is feasible to perform ULF-MRI measurements in unshielded urban environment without imaging artifacts originating from magnetic fluctuations by using the active compensation technique and/or strong gradient fields.

  6. Effect of magnetic field fluctuation on ultra-low field MRI measurements in the unshielded laboratory environment.

    PubMed

    Liu, Chao; Chang, Baolin; Qiu, Longqing; Dong, Hui; Qiu, Yang; Zhang, Yi; Krause, Hans-Joachim; Offenhäusser, Andreas; Xie, Xiaoming

    2015-08-01

    Magnetic field fluctuations in our unshielded urban laboratory can reach hundreds of nT in the noisy daytime and is only a few nT in the quiet midnight. The field fluctuation causes the Larmor frequency fL to drift randomly for several Hz during the unshielded ultra-low field (ULF) nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) measurements, thus seriously spoiling the averaging effect and causing imaging artifacts. By using an active compensation (AC) technique based on the spatial correlation of the low-frequency magnetic field fluctuation, the field fluctuation can be suppressed to tens of nT, which is a moderate situation between the noisy daytime and the quiet midnight. In this paper, the effect of the field fluctuation on ULF MRI measurements was investigated. The 1D and 2D MRI signals of a water phantom were measured using a second-order low-Tc superconducting quantum interference device (SQUID) in three fluctuation cases: severe fluctuation (noisy daytime), moderate fluctuation (daytime with AC) and minute fluctuation (quiet midnight) when different gradient fields were applied. When the active compensation is applied or when the frequency encoding gradient field Gx reaches a sufficiently strong value in our measurements, the image artifacts become invisible in all three fluctuation cases. Therefore it is feasible to perform ULF-MRI measurements in unshielded urban environment without imaging artifacts originating from magnetic fluctuations by using the active compensation technique and/or strong gradient fields. PMID:26037135

  7. Hydrogeologic effects of natural disruptive events on nuclear waste repositories

    SciTech Connect

    Davis, S.N.

    1980-06-01

    Some possible hydrogeologic effects of disruptive events that may affect repositories for nuclear wastte are described. A very large number of combinations of natural events can be imagined, but only those events which are judged to be most probable are covered. Waste-induced effects are not considered. The disruptive events discussed above are placed into four geologic settings. Although the geology is not specific to given repository sites that have been considered by other agencies, the geology has been generalized from actual field data and is, therefore, considered to be physically reasonable. The geologic settings considered are: (1) interior salt domes of the Gulf Coast, (2) bedded salt of southeastern New Mexico, (3) argillaceous rocks of southern Nevanda, and (4) granitic stocks of the Basin and Range Province. Log-normal distributions of permeabilities of rock units are given for each region. Chapters are devoted to: poresity and permeability of natural materials, regional flow patterns, disruptive events (faulting, dissolution of rock forming minerals, fracturing from various causes, rapid changes of hydraulic regimen); possible hydrologic effects of disruptive events; and hydraulic fracturing.

  8. The effective field theory of dark energy

    NASA Astrophysics Data System (ADS)

    Gubitosi, Giulia; Piazza, Federico; Vernizzi, Filippo

    2013-02-01

    We propose a universal description of dark energy and modified gravity that includes all single-field models. By extending a formalism previously applied to inflation, we consider the metric universally coupled to matter fields and we write in terms of it the most general unitary gauge action consistent with the residual unbroken symmetries of spatial diffeomorphisms. Our action is particularly suited for cosmological perturbation theory: the background evolution depends on only three operators. All other operators start at least at quadratic order in the perturbations and their effects can be studied independently and systematically. In particular, we focus on the properties of a few operators which appear in non-minimally coupled scalar-tensor gravity and galileon theories. In this context, we study the mixing between gravity and the scalar degree of freedom. We assess the quantum and classical stability, derive the speed of sound of fluctuations and the renormalization of the Newton constant. The scalar can always be de-mixed from gravity at quadratic order in the perturbations, but not necessarily through a conformal rescaling of the metric. We show how to express covariant field-operators in our formalism and give several explicit examples of dark energy and modified gravity models in our language. Finally, we discuss the relation with the covariant EFT methods recently appeared in the literature.

  9. Line broadening interference for high-resolution nuclear magnetic resonance spectra under inhomogeneous magnetic fields

    SciTech Connect

    Wei, Zhiliang; Yang, Jian; Lin, Yanqin E-mail: chenz@xmu.edu.cn; Chen, Zhong E-mail: chenz@xmu.edu.cn; Chen, Youhe

    2015-04-07

    Nuclear magnetic resonance spectroscopy serves as an important tool for analyzing chemicals and biological metabolites. However, its performance is subject to the magnetic-field homogeneity. Under inhomogeneous fields, peaks are broadened to overlap each other, introducing difficulties for assignments. Here, we propose a method termed as line broadening interference (LBI) to provide high-resolution information under inhomogeneous magnetic fields by employing certain gradients in the indirect dimension to interfere the magnetic-field inhomogeneity. The conventional spectral-line broadening is thus interfered to be non-diagonal, avoiding the overlapping among adjacent resonances. Furthermore, an inhomogeneity correction algorithm is developed based on pattern recognition to recover the high-resolution information from LBI spectra. Theoretical deductions are performed to offer systematic and detailed analyses on the proposed method. Moreover, experiments are conducted to prove the feasibility of the proposed method for yielding high-resolution spectra in inhomogeneous magnetic fields.

  10. Partial homogeneity based high-resolution nuclear magnetic resonance spectra under inhomogeneous magnetic fields

    SciTech Connect

    Wei, Zhiliang; Lin, Liangjie; Lin, Yanqin E-mail: chenz@xmu.edu.cn; Chen, Zhong E-mail: chenz@xmu.edu.cn; Chen, Youhe

    2014-09-29

    In nuclear magnetic resonance (NMR) technique, it is of great necessity and importance to obtain high-resolution spectra, especially under inhomogeneous magnetic fields. In this study, a method based on partial homogeneity is proposed for retrieving high-resolution one-dimensional NMR spectra under inhomogeneous fields. Signals from series of small voxels, which characterize high resolution due to small sizes, are recorded simultaneously. Then, an inhomogeneity correction algorithm is developed based on pattern recognition to correct the influence brought by field inhomogeneity automatically, thus yielding high-resolution information. Experiments on chemical solutions and fish spawn were carried out to demonstrate the performance of the proposed method. The proposed method serves as a single radiofrequency pulse high-resolution NMR spectroscopy under inhomogeneous fields and may provide an alternative of obtaining high-resolution spectra of in vivo living systems or chemical-reaction systems, where performances of conventional techniques are usually degenerated by field inhomogeneity.

  11. Nuclear forces

    SciTech Connect

    Machleidt, R.

    2013-06-10

    These lectures present an introduction into the theory of nuclear forces. We focus mainly on the modern approach, in which the forces between nucleons emerge from low-energy QCD via chiral effective field theory.

  12. Phase II: Field Detector Development For Undeclared/Declared Nuclear Testing For Treaty Verfiation Monitoring

    SciTech Connect

    Kriz, M.; Hunter, D.; Riley, T.

    2015-10-02

    Radioactive xenon isotopes are a critical part of the Comprehensive Nuclear Test Ban Treaty (CTBT) for the detection or confirmation of nuclear weapons tests as well as on-site treaty verification monitoring. On-site monitoring is not currently conducted because there are no commercially available small/robust field detector devices to measure the radioactive xenon isotopes. Xenon is an ideal signature to detect clandestine nuclear events since they are difficult to contain and can diffuse and migrate through soils due to their inert nature. There are four key radioxenon isotopes used in monitoring: 135Xe (9 hour half-life), 133mXe (2 day half-life), 133Xe (5 day half-life) and 131mXe (12 day half-life) that decay through beta emission and gamma emission. Savannah River National Laboratory (SRNL) is a leader in the field of gas collections and has developed highly selective molecular sieves that allow for the collection of xenon gas directly from air. Phase I assessed the development of a small, robust beta-gamma coincidence counting system, that combines collection and in situ detection methodologies. Phase II of the project began development of the custom electronics enabling 2D beta-gamma coincidence analysis in a field portable system. This will be a significant advancement for field detection/quantification of short-lived xenon isotopes that would not survive transport time for laboratory analysis.

  13. Polycrystalline silicon ion sensitive field effect transistors

    NASA Astrophysics Data System (ADS)

    Yan, F.; Estrela, P.; Mo, Y.; Migliorato, P.; Maeda, H.; Inoue, S.; Shimoda, T.

    2005-01-01

    We report the operation of polycrystalline silicon ion sensitive field effect transistors. These devices can be fabricated on inexpensive disposable substrates such as glass or plastics and are, therefore, promising candidates for low cost single-use intelligent multisensors. In this work we have developed an extended gate structure with a Si3N4 sensing layer. Nearly ideal pH sensitivity (54mV /pH) and stable operation have been achieved. Temperature effects have been characterized. A penicillin sensor has been fabricated by functionalizing the sensing area with penicillinase. The sensitivity to penicillin G is about 10mV/mM, in solutions with concentration lower than the saturation value, which is about 7 mM.

  14. Radiation Effects on Current Field Programmable Technologies

    NASA Technical Reports Server (NTRS)

    Katz, R.; LaBel, K.; Wang, J. J.; Cronquist, B.; Koga, R.; Penzin, S.; Swift, G.

    1997-01-01

    Manufacturers of field programmable gate arrays (FPGAS) take different technological and architectural approaches that directly affect radiation performance. Similar y technological and architectural features are used in related technologies such as programmable substrates and quick-turn application specific integrated circuits (ASICs). After analyzing current technologies and architectures and their radiation-effects implications, this paper includes extensive test data quantifying various devices total dose and single event susceptibilities, including performance degradation effects and temporary or permanent re-configuration faults. Test results will concentrate on recent technologies being used in space flight electronic systems and those being developed for use in the near term. This paper will provide the first extensive study of various configuration memories used in programmable devices. Radiation performance limits and their impacts will be discussed for each design. In addition, the interplay between device scaling, process, bias voltage, design, and architecture will be explored. Lastly, areas of ongoing research will be discussed.

  15. State-of-the-art of beyond mean field theories with nuclear density functionals

    NASA Astrophysics Data System (ADS)

    Egido, J. Luis

    2016-07-01

    We present an overview of different beyond mean field theories (BMFTs) based on the generator coordinate method (GCM) and the recovery of symmetries used in many body nuclear physics with effective forces. In a first step a short reminder of the Hartree–Fock–Bogoliubov (HFB) theory is given. A general discussion of the shortcomings of any mean field approximation (MFA), stemming either from the lack of the elementary symmetries (like particle number and angular momentum) or the absence of fluctuations around the mean values, is presented. The recovery of the symmetries spontaneously broken in the HFB approach, in particular the angular momentum, is necessary, among others, to describe excited states and transitions. Particle number projection is also needed to guarantee the right number of protons and neutrons. Furthermore a projection before the variation prevents the pairing collapse in the weak pairing regime. A whole chapter is devoted to illustrate with examples the convenience of recovering symmetries and the differences between the projection before and after the variation. The lack of fluctuations around the average values of the MFA is a big shortcoming inherent to this approach. To build in correlations in BMFT one selects the relevant degrees of freedom of the atomic nucleus. In the low energy part of the spectrum these are the quadrupole, octupole and the pairing vibrations as well as the single particle degrees of freedom. In the GCM the operators representing these degrees of freedom are used as coordinates to generate, by the constrained (projected) HFB theory, a collective subspace. The highly correlated GCM wave function is finally written as a linear combination of a projected basis of this space. The variation of the coefficients of the linear combination leads to the Hill–Wheeler equation. The flexibility of the GCM Ansatz allows to describe a whole palette of physical situations by conveniently choosing the generator coordinates. We

  16. Dual field effects in spinel ferrite field effect devices: electrostatic carrier doping and redox reactions

    NASA Astrophysics Data System (ADS)

    Tanaka, Hidekazu

    2015-03-01

    Spinel ferrite is a good candidate as a tunable magnetic semiconductor with high TC. Here, we report the gate-induced conductance modulation of (Fe3-xZnx) O4 solid solution to demonstrate the dual contributions of volatile and non-volatile field effects arising from electronic carrier doping and redox reactions using field effect device structure with a ferroelectric Pb(Zr,Ti)O3 and an ionic liquid DEME-TFSI. In the Pb(Zr,Ti)O3/(Fe2.5Zn0.5) O4 FET, the gate voltage dependence of channel conductance on the (Fe,Zn)3O4 layer shows the typical hysteresis behavior reflecting the ferroelectric polarization, indicating the static carrier modulation . In contrast, in the DEME-TFSI/(Fe2.5Zn0.5) O4 FET, a large hysteresis observed in the drain current vs gate voltage characteristics is not accounted for solely by electrostatic doping, strongly suggesting the presence of chemical reactions. In more details, the characteristic hysteresis virtually disappears for the heavily Zn substituted system,(Fe2.2Zn0.8) O4 with less carrier concentration. These observations revealed the coexistence of two types of field effects in the Fe3-xZnxO4 devices, and the tuning of field-effect characteristics via composition engineering should be extremely useful for fabricating high-performance oxide field-effect devices.

  17. Molecular dynamics and composition of crude oil by low-field nuclear magnetic resonance.

    PubMed

    Jia, Zijian; Xiao, Lizhi; Wang, Zhizhan; Liao, Guangzhi; Zhang, Yan; Liang, Can

    2016-08-01

    Nuclear magnetic resonance (NMR) techniques are widely used to identify pure substances and probe protein dynamics. Oil is a complex mixture composed of hydrocarbons, which have a wide range of molecular size distribution. Previous work show that empirical correlations of relaxation times and diffusion coefficients were found for simple alkane mixtures, and also the shape of the relaxation and diffusion distribution functions are related to the composition of the fluids. The 2D NMR is a promising qualitative evaluation method for oil composition. But uncertainty in the interpretation of crude oil indicated further study was required. In this research, the effect of each composition on relaxation distribution functions is analyzed in detail. We also suggest a new method for prediction of the rotational correlation time distribution of crude oil molecules using low field NMR (LF-NMR) relaxation time distributions. A set of down-hole NMR fluid analysis system is independently designed and developed for fluid measurement. We illustrate this with relaxation-relaxation correlation experiments and rotational correlation time distributions on a series of hydrocarbon mixtures that employ our laboratory-designed downhole NMR fluid analyzer. The LF-NMR is a useful tool for detecting oil composition and monitoring oil property changes. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26990450

  18. Radionuclide observables during the Integrated Field Exercise of the Comprehensive Nuclear-Test-Ban Treaty.

    PubMed

    Burnett, Jonathan L; Miley, Harry S; Milbrath, Brian D

    2016-03-01

    In 2014 the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) undertook an Integrated Field Exercise (IFE14) in Jordan. The exercise consisted of a simulated 0.5-2 kT underground nuclear explosion triggering an On-site Inspection (OSI) to search for evidence of a Treaty violation. This research paper evaluates two of the OSI techniques used during the IFE14, laboratory-based gamma-spectrometry of soil samples and in-situ gamma-spectrometry, both of which were implemented to search for 17 OSI relevant particulate radionuclides indicative of nuclear explosions. The detection sensitivity is evaluated using real IFE and model data. It indicates that higher sensitivity laboratory measurements are the optimum technique during the IFE and within the Treaty/Protocol-specified OSI timeframes. PMID:26802699

  19. The acoustic field in the ionosphere caused by an underground nuclear explosion

    NASA Astrophysics Data System (ADS)

    Krasnov, V. M.; Drobzheva, Ya. V.

    2005-07-01

    The problem of describing the generation and propagation of an infrasonic wave emitted by a finite extended source in the inhomogeneous absorbing atmosphere is the focus of this paper. It is of interest since the role of infrasonic waves in the energy balance of the upper atmosphere remains largely unknown. We present an algorithm, which allows adaptation of a point source model for calculating the infrasonic field from an underground nuclear explosion at ionospheric altitudes. Our calculations appear to agree remarkably well with HF Doppler sounding data measured for underground nuclear explosions at the Semipalatinsk Test Site. We show that the temperature and ionospheric electron density perturbation caused by an acoustic wave from underground nuclear explosion can reach 10% of background levels.

  20. Monitoring microbial growth and activity using spectral induced polarization and low-field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Keating, Kristina; Revil, Andre

    2015-04-01

    Microbes and microbial activities in the Earth's subsurface play a significant role in shaping subsurface environments and are involved in environmental applications such as remediation of contaminants in groundwater and oil fields biodegradation. Stimulated microbial growth in such applications could cause wide variety of changes of physical/chemical properties in the subsurface. It is critical to monitor and determine the fate and transportation of microorganisms in the subsurface during such applications. Recent geophysical studies demonstrate the potential of two innovative techniques, spectral induced polarization (SIP) and low-field nuclear magnetic resonance (NMR), for monitoring microbial growth and activities in porous media. The SIP measures complex dielectric properties of porous media at low frequencies of exciting electric field, and NMR studies the porous structure of geologic media and characterizes fluids subsurface. In this laboratory study, we examined both SIP and NMR responses from bacterial growth suspension as well as suspension mixed with silica sands. We focus on the direct contribution of microbes to the SIP and NMR signals in the absence of biofilm formation or biomineralization. We used Zymomonas mobilis and Shewanella oneidensis (MR-1) for SIP and NMR measurements, respectively. The SIP measurements were collected over the frequency range of 0.1 - 1 kHz on Z. mobilis growth suspension and suspension saturated sands at different cell densities. SIP data show two distinct peaks in imaginary conductivity spectra, and both imaginary and real conductivities increased as microbial density increased. NMR data were collected using both CPMG pulse sequence and D-T2 mapping to determine the T2-distribution and diffusion properties on S. oneidensis suspension, pellets (live and dead), and suspension mixed with silica sands. NMR data show a decrease in the T2-distribution in S. oneidensis suspension saturated sands as microbial density increase. A

  1. Thermal effects on nuclear symmetry energy with a momentum-dependent effective interaction

    SciTech Connect

    Moustakidis, Ch. C.

    2007-08-15

    The knowledge of the nuclear symmetry energy of hot neutron-rich matter is important for understanding the dynamical evolution of massive stars and the supernova explosion mechanisms. In particular, the electron capture rate on nuclei and/or free protons in presupernova explosions is especially sensitive to the symmetry energy at finite temperature. In view of the above, in the present work we calculate the symmetry energy as a function of the temperature for various values of the baryon density by applying a momentum-dependent effective interaction. In addition to a previous work, the thermal effects are studied separately both in the kinetic part and the interaction part of the symmetry energy. We focus also on the calculations of the mean-field potential, employed extensively in heavy-ion reaction research, both for nuclear and pure neutron matter. The proton fraction and the electron chemical potential, which are crucial quantities for representing the thermal evolution of supernova and neutron stars, are calculated for various values of the temperature. Finally, we construct a temperature dependent equation of state of {beta}-stable nuclear matter, the basic ingredient for the evaluation of the neutron star properties.

  2. Effective Field Theory for Rydberg Polaritons

    NASA Astrophysics Data System (ADS)

    Gullans, M. J.; Wang, Y.; Thompson, J. D.; Liang, Q.-Y.; Vuletic, V.; Lukin, M. D.; Gorshkov, A. V.

    2016-05-01

    Photons can be made to strongly interact by dressing them with atomic Rydberg states under conditions of electromagnetic induced transparency. Probing Rydberg polaritons in the few-body limit, recent experiments were able to observe non-perturbative two-body effects including: single photon switching and the formation of bound states. Although the two-body problem is amenable to exact solutions, such approaches quickly become intractable for more than two particles. To overcome this problem, we study non-perturbative effects in N-body scattering of Rydberg polaritons using effective field theory (EFT). For attractive interactions, we show how a suitably long medium can be used to prepare shallow N-body bound states in one dimension. We verify this prediction for two and three photons using full numerical simulations. We then consider conditions under which the effective interactions are repulsive and study two and three photon transmission. Finally, we show how to go beyond EFT by measuring the three-body contact force or, alternatively, scattering at high relative momenta.

  3. Electromagnetic field induced biological effects in humans.

    PubMed

    Kaszuba-Zwolińska, Jolanta; Gremba, Jerzy; Gałdzińska-Calik, Barbara; Wójcik-Piotrowicz, Karolina; Thor, Piotr J

    2015-01-01

    Exposure to artificial radio frequency electromagnetic fields (EMFs) has increased significantly in recent decades. Therefore, there is a growing scientific and social interest in its influence on health, even upon exposure significantly below the applicable standards. The intensity of electromagnetic radiation in human environment is increasing and currently reaches astronomical levels that had never before experienced on our planet. The most influential process of EMF impact on living organisms, is its direct tissue penetration. The current established standards of exposure to EMFs in Poland and in the rest of the world are based on the thermal effect. It is well known that weak EMF could cause all sorts of dramatic non-thermal effects in body cells, tissues and organs. The observed symptoms are hardly to assign to other environmental factors occurring simultaneously in the human environment. Although, there are still ongoing discussions on non-thermal effects of EMF influence, on May 31, 2011--International Agency for Research on Cancer (IARC)--Agenda of World Health Organization (WHO) has classified radio electromagnetic fields, to a category 2B as potentially carcinogenic. Electromagnetic fields can be dangerous not only because of the risk of cancer, but also other health problems, including electromagnetic hypersensitivity (EHS). Electromagnetic hypersensitivity (EHS) is a phenomenon characterized by the appearance of symptoms after exposure of people to electromagnetic fields, generated by EHS is characterized as a syndrome with a broad spectrum of non-specific multiple organ symptoms including both acute and chronic inflammatory processes located mainly in the skin and nervous systems, as well as in respiratory, cardiovascular systems, and musculoskeletal system. WHO does not consider the EHS as a disease-- defined on the basis of medical diagnosis and symptoms associated with any known syndrome. The symptoms may be associated with a single source of EMF

  4. Low magnetic field dynamic nuclear polarization using a single-coil two-channel probe

    SciTech Connect

    TonThat, D.M.; Augustine, M.P.; Pines, A.; Clarke, J. |

    1997-03-01

    We describe the design and construction of a single-coil, two-channel probe for the detection of low-field magnetic resonance using dynamic nuclear polarization (DNP). The high-frequency channel of the probe, which is used to saturate the electron spins, is tuned to the electron Larmor frequency, 75 MHz at 2.7 mT, and matched to 50 {Omega}. Low-field, {sup 1}H nuclear magnetic resonance (NMR) is detected through the second, low-frequency channel at frequencies {lt}1 MHz. The performance of the probe was tested by measuring the DNP of protons in a manganese (II) chloride solution at 2.7 mT. At the proton NMR frequency of 120 kHz, the signal amplitude was enhanced over the value without DNP by a factor of about 200. {copyright} {ital 1997 American Institute of Physics.}

  5. Relativistic effects in nuclear many-body systems

    SciTech Connect

    Coester, F.

    1985-01-01

    Different approaches to the formulation of relativistic many-body dynamics yield different perspectives of nature and the magnitude of ''relativistic effects''. The effects of Lorentz invariance appear to be relatively unimportant. Important dynamical features of spinorial many-body formalisms are effects of subnuclear degrees of freedom which are represented in the many-body forces of the covariant nuclear Hamiltonian. 24 refs.

  6. Intelligent monitor functional model with ionization chamber for mixed nuclear radiation field measurements

    SciTech Connect

    Valcov, N.; Purghel, L.; Celarel, A.

    1998-12-31

    By using the statistical discrimination technique, the components of an ionization current, due to a mixed radiation field, may be simultaneously measured. A functional model, including a series manufactured gamma-ray ratemeter was done, as an intermediate step in the design of specialized nuclear instrumentation, in order to check the concept of statistical discrimination method. The obtained results are in good agreement with the estimations of the statistical discrimination method.

  7. Magnetic Field Effects on Plasma Plumes

    NASA Technical Reports Server (NTRS)

    Ebersohn, F.; Shebalin, J.; Girimaji, S.; Staack, D.

    2012-01-01

    Here, we will discuss our numerical studies of plasma jets and loops, of basic interest for plasma propulsion and plasma astrophysics. Space plasma propulsion systems require strong guiding magnetic fields known as magnetic nozzles to control plasma flow and produce thrust. Propulsion methods currently being developed that require magnetic nozzles include the VAriable Specific Impulse Magnetoplasma Rocket (VASIMR) [1] and magnetoplasmadynamic thrusters. Magnetic nozzles are functionally similar to de Laval nozzles, but are inherently more complex due to electromagnetic field interactions. The two crucial physical phenomenon are thrust production and plasma detachment. Thrust production encompasses the energy conversion within the nozzle and momentum transfer to a spacecraft. Plasma detachment through magnetic reconnection addresses the problem of the fluid separating efficiently from the magnetic field lines to produce maximum thrust. Plasma jets similar to those of VASIMR will be studied with particular interest in dual jet configurations, which begin as a plasma loops between two nozzles. This research strives to fulfill a need for computational study of these systems and should culminate with a greater understanding of the crucial physics of magnetic nozzles with dual jet plasma thrusters, as well as astrophysics problems such as magnetic reconnection and dynamics of coronal loops.[2] To study this problem a novel, hybrid kinetic theory and single fluid magnetohydrodynamic (MHD) solver known as the Magneto-Gas Kinetic Method is used.[3] The solver is comprised of a "hydrodynamic" portion based on the Gas Kinetic Method and a "magnetic" portion that accounts for the electromagnetic behaviour of the fluid through source terms based on the resistive MHD equations. This method is being further developed to include additional physics such as the Hall effect. Here, we will discuss the current level of code development, as well as numerical simulation results

  8. The effective field theory treatment of quantum gravity

    SciTech Connect

    Donoghue, John F.

    2012-09-24

    This is a pedagogical introduction to the treatment of quantum general relativity as an effective field theory. It starts with an overview of the methods of effective field theory and includes an explicit example. Quantum general relativity matches this framework and I discuss gravitational examples as well as the limits of the effective field theory. I also discuss the insights from effective field theory on the gravitational effects on running couplings in the perturbative regime.

  9. DOSIMETRIC response of a REM-500 in low energy neutron fields typical of nuclear power plants.

    PubMed

    Aslam; Matysiak, W; Atanackovic, J; Waker, A J

    2012-06-01

    This study investigates the response of a REM-500 to assess neutron quality factor and dose equivalent in low energy neutron fields, which are commonly encountered in the workplace environment of nuclear power stations. The McMaster University 3 MV Van de Graaff accelerator facility was used to measure the response of the instrument in monoenergetic neutron fields in the energy range 51 to 727 keV by bombarding a thin LiF target with 1.93-2.50 MeV protons. The energy distribution of the neutron fields produced in the facility was measured by a (3)He filled gas ionization chamber. The MCA mode of the REM-500 instrument was used to collect lineal energy distributions at varying neutron energies and to calculate the frequency and dose-mean lineal energies. The effective quality factor, Q-, was also calculated using the values of Q(y)listed in the REM-500 operation manual and compared with those of ICRP 60. The authors observed a continuously increasing trend in y - F, y-D, and Q-with an increase in neutron energy. It is interesting to note that standard tissue equivalent proportional counters (TEPCs) filled with tissue equivalent(TE) gas give rise to a similar trend for these microdosimetric quantities of interest in the same energy range; however, the averages calculated in this study are larger by about 15%compared to a TEPC filled with propane-based TE gas probably because of the larger stopping power of protons in propane compared to TE gas. These somewhat larger event sizes did not result in any significant increase in the Q-compared to those obtained from a TEPC filled with TE gas and were found to be in good agreement with other measurements reported earlier at corresponding neutron energies. The instrument quality factor response, R(Q), defined as the ratio of measured quality factor to the calculated quality factor in an ICRU tissue sphere,was found to vary with neutron energy. The instrument response,R(Q), was ~0.6 at 727 keV, which deteriorates further to

  10. Natural geochemical analogues of the near field of high-level nuclear waste repositories

    SciTech Connect

    Apps, J.A.

    1995-09-01

    United States practice has been to design high-level nuclear waste (HLW) geological repositories with waste densities sufficiently high that repository temperatures surrounding the waste will exceed 100{degrees}C and could reach 250{degrees}C. Basalt and devitrified vitroclastic tuff are among the host rocks considered for waste emplacement. Near-field repository thermal behavior and chemical alteration in such rocks is expected to be similar to that observed in many geothermal systems. Therefore, the predictive modeling required for performance assessment studies of the near field could be validated and calibrated using geothermal systems as natural analogues. Examples are given which demonstrate the need for refinement of the thermodynamic databases used in geochemical modeling of near-field natural analogues and the extent to which present models can predict conditions in geothermal fields.

  11. Biological effects of electric fields: an overview

    SciTech Connect

    Anderson, L.E.; Phillips, R.D.

    1983-11-01

    An overview of the literature suggests tha electric-field exposure is an environmental agent/influence of relatively low potential toxicity to biological systems. Generally, many of the biological effects which have been reported are quite subtle and differences between exposed and unexposed subjects may be masked by normal biological variations. However, several recent reports indicate possibly more serious consequences from chronic exposure, emphasizing the need for more research in epidemiology and laboratory experiments. This paper presents a cursory overview of investigations on the biological consequences of exposure to ELF electromagnetic fields. Three important topics are discussed, including: 1) the general methodology of exposure experiments, including those elements which are critical for definitive studies in biological systems; 2) a brief discussion of epidemiological and clinical studies conducted to date; and 3) a somewhat more extensive examination of animal experiments representing major areas of investigation (behavior, biological rhythms, nervous and endocrine systems, bone growth and repair, cardiovascular system and blood chemistry, immunology, reproduction, growth and development mortality and pathology, cellular and membrane studies, and mutagenesis). A discussion of current concepts, possible mechanisms and future directions of research is presented. 110 references.

  12. Quarkonium hybrids with nonrelativistic effective field theories

    NASA Astrophysics Data System (ADS)

    Berwein, Matthias; Brambilla, Nora; Tarrús Castellà, Jaume; Vairo, Antonio

    2015-12-01

    We construct a nonrelativistic effective field theory description of heavy quarkonium hybrids from QCD. We identify the symmetries of the system made of a heavy quark, a heavy antiquark, and glue in the static limit. Corrections to this limit can be obtained order by order in an expansion in the inverse of the mass m of the heavy quark. At order 1 /m in the expansion, we obtain, at the level of potential nonrelativistic QCD, a system of coupled Schrödinger equations that describes hybrid spin-symmetry multiplets, including the mixing of different static energies into the hybrid states, an effect known as Λ doubling in molecular physics. In the short distance, the static potentials depend on two nonperturbative parameters, the gluelump mass and the quadratic slope, which can be determined from lattice calculations. We adopt a renormalon subtraction scheme for the calculation of the perturbative part of the potential. We numerically solve the coupled Schrödinger equations and obtain the masses for the lowest lying spin-symmetry multiplets for c c ¯, b c ¯, and b b ¯ hybrids. The Λ -doubling effect breaks the degeneracy between opposite-parity spin-symmetry multiplets and lowers the mass of the multiplets that get mixed contributions of different static energies. We compare our findings to the experimental data, direct lattice computations, and sum rule calculations, and discuss the relation to the Born-Oppenheimer approximation.

  13. Electric field effect in ultrathin black phosphorus

    SciTech Connect

    Koenig, Steven P.; Schmidt, Hennrik; Doganov, Rostislav A.; Castro Neto, A. H.; Özyilmaz, Barbaros

    2014-03-10

    Black phosphorus exhibits a layered structure similar to graphene, allowing mechanical exfoliation of ultrathin single crystals. Here, we demonstrate few-layer black phosphorus field effect devices on Si/SiO{sub 2} and measure charge carrier mobility in a four-probe configuration as well as drain current modulation in a two-point configuration. We find room-temperature mobilities of up to 300 cm{sup 2}/Vs and drain current modulation of over 10{sup 3}. At low temperatures, the on-off ratio exceeds 10{sup 5}, and the device exhibits both electron and hole conduction. Using atomic force microscopy, we observe significant surface roughening of thin black phosphorus crystals over the course of 1 h after exfoliation.

  14. Bayesian parameter estimation for effective field theories

    NASA Astrophysics Data System (ADS)

    Wesolowski, S.; Klco, N.; Furnstahl, R. J.; Phillips, D. R.; Thapaliya, A.

    2016-07-01

    We present procedures based on Bayesian statistics for estimating, from data, the parameters of effective field theories (EFTs). The extraction of low-energy constants (LECs) is guided by theoretical expectations in a quantifiable way through the specification of Bayesian priors. A prior for natural-sized LECs reduces the possibility of overfitting, and leads to a consistent accounting of different sources of uncertainty. A set of diagnostic tools is developed that analyzes the fit and ensures that the priors do not bias the EFT parameter estimation. The procedures are illustrated using representative model problems, including the extraction of LECs for the nucleon-mass expansion in SU(2) chiral perturbation theory from synthetic lattice data.

  15. An effective field theory approach to the stabilization of 8Be in a QED plasma

    NASA Astrophysics Data System (ADS)

    Yao, Xiaojun; Mehen, Thomas; Müller, Berndt

    2016-07-01

    We use effective field theory to study the α –α resonant scattering in a finite-temperature QED plasma. The static plasma screening effect causes the resonance state 8Be to live longer and eventually leads to the formation of a bound state when {m}{{D}}≳ 0.3 {{MeV}}. We speculate that this effect may have implications on the rates of cosmologically and astrophysically relevant nuclear reactions involving α particles.

  16. Further analysis of field effects on liquids and solidification

    NASA Technical Reports Server (NTRS)

    Seiler, R. F.; Miller, R. I.; Chen, W. S.

    1974-01-01

    Numerical calculations of the magnitude of external field effects on liquids are presented to describe how external fields can influence the substructure of the field. Quantitative estimates of magnetic and gravitational effects are reported on melts of metals and semiconductors. The results are condensed in tables which contain the input data for calculation of the field effects on diffusion coefficient, solidification rate and for calculation of field forces on individual molecules in the melt.

  17. Field effect sensors for PCR applications

    NASA Astrophysics Data System (ADS)

    Taing, Meng-Houit; Sweatman, Denis R.

    2004-03-01

    The use of field effect sensors for biological and chemical sensing is widely employed due to its ability to make detections based on charge and surface potential. Because proteins and DNA almost always carry a charge [1], silicon can be used to micro fabricate such a sensor. The EIS structure (Electrolyte on Insulator on Silicon) provides a novel, label-free and simple to fabricate way to make a field effect DNA detection sensor. The sensor responds to fluctuating capacitance caused by a depletion layer thickness change at the surface of the silicon substrate through DNA adsorption onto the dielectric oxide/PLL (Poly-L-Lysine) surface. As DNA molecules diffuse to the sensor surface, they are bound to their complimentary capture probes deposited on the surface. The negative charge exhibited by the DNA forces negative charge carriers in the substrate to move away from the surface. This causes an n-type depletion layer substrate to thicken and a p-type to thin. The depletion layer thickness can be measured by its capacitance using an LCR meter. This experiment is conducted using the ConVolt (constant voltage) approach. Nucleic acids are amplified by an on chip PCR (Polymerase Chain Reaction) system and then fed into the sensor. The low ionic solution strength will ensure that counter-ions do not affect the sensor measurements. The sensor surface contains capture probes that bind to the pathogen. The types of pathogens we"ll be detecting include salmonella, campylobacter and E.Coli DNA. They are held onto the sensor surface by the positively charged Poly-L-Lysine layer. The electrolyte is biased through a pseudo-reference electrode. Pseudo reference electrodes are usually made from metals such as Platinum or Silver. The problem associated with "floating" biasing electrodes is they cannot provide stable biasing potentials [2]. They drift due to surface charging effects and trapped charges on the surface. To eliminate this, a differential system consisting of 2 sensors

  18. Hydrogel Actuation by Electric Field Driven Effects

    NASA Astrophysics Data System (ADS)

    Morales, Daniel Humphrey

    Hydrogels are networks of crosslinked, hydrophilic polymers capable of absorbing and releasing large amounts of water while maintaining their structural integrity. Polyelectrolyte hydrogels are a subset of hydrogels that contain ionizable moieties, which render the network sensitive to the pH and the ionic strength of the media and provide mobile counterions, which impart conductivity. These networks are part of a class of "smart" material systems that can sense and adjust their shape in response to the external environment. Hence, the ability to program and modulate hydrogel shape change has great potential for novel biomaterial and soft robotics applications. We utilized electric field driven effects to manipulate the interaction of ions within polyelectrolyte hydrogels in order to induce controlled deformation and patterning. Additionally, electric fields can be used to promote the interactions of separate gel networks, as modular components, and particle assemblies within gel networks to develop new types of soft composite systems. First, we present and analyze a walking gel actuator comprised of cationic and anionic gel legs attached by electric field-promoted polyion complexation. We characterize the electro-osmotic response of the hydrogels as a function of charge density and external salt concentration. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices in aqueous solutions. An 'ionoprinting' technique is presented with the capability to topographically structure and actuate hydrated gels in two and three dimensions by locally patterning ions induced by electric fields. The bound charges change the local mechanical properties of the gel to induce relief patterns and evoke localized stress, causing rapid folding in air. The ionically patterned hydrogels exhibit programmable temporal and spatial shape transitions which can be tuned by the duration and/or strength of

  19. SCOPE 28: Environmental consequences of nuclear war. Volume II. Ecological and agricultural effects

    SciTech Connect

    Harwell, M.A.; Hutchinson, T.C.; Cropper, W.P. Jr.; Harwell, C.C.; Grover, H.D.

    1985-01-01

    This book presents papers on the environmental and biological impacts of nuclear weapons. Topics considered include ecological principles relevant to nuclear war, the vulnerability of ecological systems to the climatic effects of nuclear war, additional potential effects of nuclear war on ecological systems, the potential effects of nuclear war on agricultural productivity, food availability after nuclear war, experiences and extrapolations from Hiroshima and Nagasaki, and the integration of effects on human populations.

  20. Nucleon structure at large x: nuclear effects in deuterium

    SciTech Connect

    Wally Melnitchouk

    2010-07-01

    I review quark momentum distributions in the nucleon at large momentum fractions x. Particular attention is paid to the impact of nuclear effects in deuterium on the d/u quark distribution ratio as x -> 1. A new global study of parton distributions, using less restrictive kinematic cuts in Q^2 and W^2, finds strong suppression of the d quark distribution once nuclear corrections are accounted for.

  1. Health effects of the nuclear accident at Three Mile Island

    SciTech Connect

    Fabrikant, J.I.

    1980-05-01

    Between March 28 and April 15, 1979 the collective dose resulting from the radioactivity released to the population living within a 50-mile radius of the Three Mile Island nuclear plant was about 2000 person-rems, less than 1% of the annual natural background level. The average dose to a person living within 5 miles of the nuclear plant was less than 10% of annual background radiation. The maximum estimated radiation dose received by any one individual in the general population (excluding the nuclear plant workers) during the accident was 70 mrem. The doses received by the general population as a result of the accident were so small that there will be no detectable additional cases of cancer, developmental abnormalities, or genetic ill-health. Three Three Mile Island nuclear workers received radiation doses of about 3 to 4 rem, exceeding maximum permissible quarterly dose of 3 rem. The major health effect of the accident at Three Mile Island was that of a pronounced demoralizing effect on the general population in the Three Mile Island area, including teenagers and mothers of preschool children and the nuclear plant workers. However, this effect proved transient in all groups studied except the nuclear workers.

  2. Monitoring of organic contaminants in sediments using low field proton nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Rupert, Yuri

    2016-04-01

    The effective monitoring of soils and groundwater contaminated with organic compounds is an important goal of many environmental restoration efforts. Recent geophysical methods such as electrical resistivity, complex conductivity, and ground penetrating radar have been successfully applied to characterize organic contaminants in the subsurface and to monitor remediation process both in laboratory and in field. Low field proton nuclear magnetic resonance (NMR) is a geophysical tool sensitive to the molecular-scale physical and chemical environment of hydrogen-bearing fluids in geological materials and shows promise as a novel method for monitoring contaminant remediation. This laboratory research focuses on measurements on synthetic samples to determine the sensitivity of NMR to the presence of organic contaminants and improve understanding of relationships between NMR observables, hydrological properties of the sediments, and amount and state of contaminants in porous media. Toluene, a light non-aqueous phase liquid (LNAPL) has been selected as a representative organic contaminant. Three types of porous media (pure silica sands, montmorillonite clay, and various sand-clay mixtures with different sand/clay ratios) were prepared as synthetic sediments. NMR relaxation time (T2) and diffusion-relaxation (D ‑ T2) correlation measurements were performed in each sediment saturated with water and toluene mixed fluid at assorted concentrations (0% toluene and 100% water, 1% toluene and 99% water, 5% toluene and 95% water, 25% toluene and 75% water, and 100% toluene and 0% water) to 1) understand the effect of different porous media on the NMR responses in each fluid mixture, 2) investigate the role of clay content on T2 relaxation of each fluid, 3) quantify the amount hydrocarbons in the presence of water in each sediment, and 4) resolve hydrocarbons from water in D ‑ T2 map. Relationships between the compositions of porous media, hydrocarbon concentration, and

  3. Casimir effect of massive vector fields

    SciTech Connect

    Teo, L. P.

    2010-11-15

    We study the Casimir effect due to a massive vector field in a system of two parallel plates made of real materials, in an arbitrary magnetodielectric background. The plane waves satisfying the Proca equations are classified into transverse modes and longitudinal modes which have different dispersion relations. Transverse modes are further divided into type I and type II corresponding to TE and TM modes in the massless case. For general magnetodielectric media, we argue that the correct boundary conditions are the continuities of H{sub ||}, {phi}, A, and {partial_derivative}{sub x}A{sub x}, where x is the direction normal to the plates. Although there are type I transverse modes that satisfy all the boundary conditions, it is impossible to find type II transverse modes or longitudinal modes that satisfy all the boundary conditions. To circumvent this problem, type II transverse modes and longitudinal modes have to be considered together. We call the contribution to the Casimir energy from type I transverse modes TE contribution, and the contribution from the superposition of type II transverse modes and longitudinal modes TM contribution. Their massless limits give, respectively, the TE and TM contributions to the Casimir energy of a massless vector field. The limit where the plates become perfectly conducting is discussed in detail. For the special case where the background has a unity refractive index, it is shown that the TM contribution to the Casimir energy can be written as a sum of contributions from two different types of modes, corresponding to type II discrete modes and type III continuum modes discussed by Barton and Dombey [G. Barton and N. Dombey, Ann. Phys. (N.Y.) 162, 231 (1985).]. For general background, this splitting does not work. The limit where both plates become infinitely permeable and the limit where one plate becomes perfectly conducting and one plate becomes infinitely permeable are also investigated.

  4. Effects of Nuclear Interactions in Space Radiation Transport

    NASA Technical Reports Server (NTRS)

    Lin, Zi-Wei; Barghouty, A. F.

    2004-01-01

    Space radiation transport codes have been developed to calculate radiation effects behind materials in human missions to the Moon, Mars or beyond. We study how nuclear fragmentation processes affect predictions from such radiation transport codes. In particular, we investigate the effects of fragmentation cross sections at different energies on fluxes, dose and dose-equivalent from galactic cosmic rays behind typical shielding materials.

  5. Effects of Nuclear Interactions in Space Radiation Transport

    NASA Technical Reports Server (NTRS)

    Lin, Zi-Wei; Barghouty, A. F.

    2005-01-01

    Space radiation transport codes have been developed to calculate radiation effects behind materials in human mission to the Moon, Mars or beyond. We study how nuclear fragmentation processes affect predictions from such radiation transport codes. In particular, we investigate the effects of fragmentation cross sections at different energies on fluxes, dose and dose-equivalent from galactic cosmic rays behind typical shielding materials.

  6. Effects of the density dependence of the nuclear symmetry energy on the properties of superheavy nuclei

    SciTech Connect

    Jiang Weizhou

    2010-04-15

    Effects of the density dependence of the nuclear symmetry energy on ground-state properties of superheavy nuclei are studied in the relativistic mean-field theory. It is found that the softening of the symmetry energy plays an important role in the empirical shift [Phys. Rev. C 67, 024309 (2003)] of spherical orbitals in superheavy nuclei. The calculation based on the relativistic mean-field models NL3 and FSUGold supports the double shell closure in {sup 292}120 with the softening of the symmetry energy. In addition, the significant effect of the density dependence of the symmetry energy on the neutron skin thickness in superheavy nuclei is investigated.

  7. Radiation and transmutation effects relevant to solid nuclear waste forms

    SciTech Connect

    Vance, E.R.; Roy, R.; Pillay, K.K.S.

    1981-03-15

    Radiation effects in insulating solids are discussed in a general way as an introduction to the quite sparse published work on radiation effects in candidate nuclear waste forms other than glasses. Likely effects of transmutation in crystals and the chemical mitigation strategy are discussed. It seems probable that radiation effects in solidified HLW will not be serious if the actinides can be wholly incorporated in such radiation-resistant phases as monazite or uraninite.

  8. Nuclear Material Control and Accountability System Effectiveness Tool (MSET)

    SciTech Connect

    Powell, Danny H; Elwood Jr, Robert H; Roche, Charles T; Campbell, Billy J; Hammond, Glenn A; Meppen, Bruce W; Brown, Richard F

    2011-01-01

    A nuclear material control and accountability (MC&A) system effectiveness tool (MSET) has been developed in the United States for use in evaluating material protection, control, and accountability (MPC&A) systems in nuclear facilities. The project was commissioned by the National Nuclear Security Administration's Office of International Material Protection and Cooperation. MSET was developed by personnel with experience spanning more than six decades in both the U.S. and international nuclear programs and with experience in probabilistic risk assessment (PRA) in the nuclear power industry. MSET offers significant potential benefits for improving nuclear safeguards and security in any nation with a nuclear program. MSET provides a design basis for developing an MC&A system at a nuclear facility that functions to protect against insider theft or diversion of nuclear materials. MSET analyzes the system and identifies several risk importance factors that show where sustainability is essential for optimal performance and where performance degradation has the greatest impact on total system risk. MSET contains five major components: (1) A functional model that shows how to design, build, implement, and operate a robust nuclear MC&A system (2) A fault tree of the operating MC&A system that adapts PRA methodology to analyze system effectiveness and give a relative risk of failure assessment of the system (3) A questionnaire used to document the facility's current MPC&A system (provides data to evaluate the quality of the system and the level of performance of each basic task performed throughout the material balance area [MBA]) (4) A formal process of applying expert judgment to convert the facility questionnaire data into numeric values representing the performance level of each basic event for use in the fault tree risk assessment calculations (5) PRA software that performs the fault tree risk assessment calculations and produces risk importance factor reports on the

  9. Icelandic basaltic geothermal field: A natural analog for nuclear waste isolation in basalt

    SciTech Connect

    Ulmer, G.C.; Grandstaff, D.E. . Dept. of Geology)

    1984-11-21

    Analog studies of Icelandic geothermal fields have shown that the design of nuclear waste repositories in basalt can benefit by comparison to the data base already available from the development of these geothermal fields. A high degree of similarity exists between these two systems: their petrology, groundwater geochemistry, mineral solubilities, hydrologic parameters, temperature ranges, water-rock redox equilibria, hydrothermal pH values, and secondary mineralogies all show considerable overlap in the range of values. The experimentally-simulated hydrothermal studies of the basaltic nuclear waste repository rocks have, at this time, produced a data base that receives a strong confirmation from the Icelandic analog. Furthermore, the Icelandic analog should eventually be employed to extrapolate into higher and lower temperatures, into longer time-base chemical comparisons, and into more realistic mineral deposition studies, than have been possible in the laboratory evaluations of the nuclear waste repository designs. This eventual use of the Icelandic analog will require cooperative work with the Icelandic Geological Survey. 46 refs., 4 figs., 2 tabs.

  10. Hall and field-effect mobilities in few layered p-WSe₂ field-effect transistors.

    PubMed

    Pradhan, N R; Rhodes, D; Memaran, S; Poumirol, J M; Smirnov, D; Talapatra, S; Feng, S; Perea-Lopez, N; Elias, A L; Terrones, M; Ajayan, P M; Balicas, L

    2015-01-01

    Here, we present a temperature (T) dependent comparison between field-effect and Hall mobilities in field-effect transistors based on few-layered WSe2 exfoliated onto SiO2. Without dielectric engineering and beyond a T-dependent threshold gate-voltage, we observe maximum hole mobilities approaching 350 cm(2)/Vs at T = 300 K. The hole Hall mobility reaches a maximum value of 650 cm(2)/Vs as T is lowered below ~150 K, indicating that insofar WSe2-based field-effect transistors (FETs) display the largest Hall mobilities among the transition metal dichalcogenides. The gate capacitance, as extracted from the Hall-effect, reveals the presence of spurious charges in the channel, while the two-terminal sheet resistivity displays two-dimensional variable-range hopping behavior, indicating carrier localization induced by disorder at the interface between WSe2 and SiO2. We argue that improvements in the fabrication protocols as, for example, the use of a substrate free of dangling bonds are likely to produce WSe2-based FETs displaying higher room temperature mobilities, i.e. approaching those of p-doped Si, which would make it a suitable candidate for high performance opto-electronics. PMID:25759288

  11. Analysis of nuclear quantum effects on hydrogen bonding.

    PubMed

    Swalina, Chet; Wang, Qian; Chakraborty, Arindam; Hammes-Schiffer, Sharon

    2007-03-22

    The impact of nuclear quantum effects on hydrogen bonding is investigated for a series of hydrogen fluoride (HF)n clusters and a partially solvated fluoride anion, F-(H2O). The nuclear quantum effects are included using the path integral formalism in conjunction with the Car-Parrinello molecular dynamics (PICPMD) method and using the second-order vibrational perturbation theory (VPT2) approach. For the HF clusters, a directional change in the impact of nuclear quantum effects on the hydrogen-bonding strength is observed as the clusters evolve toward the condensed phase. Specifically, the inclusion of nuclear quantum effects increases the F-F distances for the (HF)n=2-4 clusters and decreases the F-F distances for the (HF)n>4 clusters. This directional change occurs because the enhanced electrostatic interactions between the HF monomers become more dominant than the zero point energy effects of librational modes as the size of the HF clusters increases. For the F-(H2O) system, the inclusion of nuclear quantum effects decreases the F-O distance and strengthens the hydrogen bonding interaction between the fluoride anion and the water molecule because of enhanced electrostatic interactions. The vibrationally averaged 19F shielding constant for F-(H2O) is significantly lower than the value for the equilibrium geometry, indicating that the electronic density on the fluorine decreases as a result of the quantum delocalization of the shared hydrogen. Deuteration of this system leads to an increase in the vibrationally averaged F-O distance and nuclear magnetic shielding constant because of the smaller degree of quantum delocalization for deuterium. PMID:17388289

  12. Field-effect electroluminescence in silicon nanocrystals.

    PubMed

    Walters, Robert J; Bourianoff, George I; Atwater, Harry A

    2005-02-01

    There is currently worldwide interest in developing silicon-based active optical components in order to leverage the infrastructure of silicon microelectronics technology for the fabrication of optoelectronic devices. Light emission in bulk silicon-based devices is constrained in wavelength to infrared emission, and in efficiency by the indirect bandgap of silicon. One promising strategy for overcoming these challenges is to make use of quantum-confined excitonic emission in silicon nanocrystals. A critical challenge for silicon nanocrystal devices based on nanocrystals embedded in silicon dioxide has been the development of a method for efficient electrical carrier injection. We report here a scheme for electrically pumping dense silicon nanocrystal arrays by a field-effect electroluminescence mechanism. In this excitation process, electrons and holes are both injected from the same semiconductor channel across a tunnelling barrier in a sequential programming process, in contrast to simultaneous carrier injection in conventional pn-junction light-emitting-diode structures. Light emission is strongly correlated with the injection of a second carrier into a nanocrystal that has been previously programmed with a charge of the opposite sign. PMID:15665836

  13. Deep-Earth reactor: Nuclear fission, helium, and the geomagnetic field

    PubMed Central

    Hollenbach, D. F.; Herndon, J. M.

    2001-01-01

    Geomagnetic field reversals and changes in intensity are understandable from an energy standpoint as natural consequences of intermittent and/or variable nuclear fission chain reactions deep within the Earth. Moreover, deep-Earth production of helium, having 3He/4He ratios within the range observed from deep-mantle sources, is demonstrated to be a consequence of nuclear fission. Numerical simulations of a planetary-scale geo-reactor were made by using the SCALE sequence of codes. The results clearly demonstrate that such a geo-reactor (i) would function as a fast-neutron fuel breeder reactor; (ii) could, under appropriate conditions, operate over the entire period of geologic time; and (iii) would function in such a manner as to yield variable and/or intermittent output power. PMID:11562483

  14. The development of the time dependence of the nuclear EMP electric field

    SciTech Connect

    Eng, C

    2009-10-30

    The nuclear electromagnetic pulse (EMP) electric field calculated with the legacy code CHAP is compared with the field given by an integral solution of Maxwell's equations, also known as the Jefimenko equation, to aid our current understanding on the factors that affect the time dependence of the EMP. For a fair comparison the CHAP current density is used as a source in the Jefimenko equation. At first, the comparison is simplified by neglecting the conduction current and replacing the standard atmosphere with a constant density air slab. The simplicity of the resultant current density aids in determining the factors that affect the rise, peak and tail of the EMP electric field versus time. The three dimensional nature of the radiating source, i.e. sources off the line-of-sight, and the time dependence of the derivative of the current density with respect to time are found to play significant roles in shaping the EMP electric field time dependence. These results are found to hold even when the conduction current and the standard atmosphere are properly accounted for. Comparison of the CHAP electric field with the Jefimenko electric field offers a direct validation of the high-frequency/outgoing wave approximation.

  15. Study on signal intensity of low field nuclear magnetic resonance via an indirect coupling measurement

    NASA Astrophysics Data System (ADS)

    Jiang, Feng-Ying; Wang, Ning; Jin, Yi-Rong; Deng, Hui; Tian, Ye; Lang, Pei-Lin; Li, Jie; Chen, Ying-Fei; Zheng, Dong-Ning

    2013-04-01

    We carry out an ultra-low-field nuclear magnetic resonance (NMR) experiment based on high-Tc superconducting quantum interference devices (SQUIDs). The measurement field is in a micro-tesla range (~10 μT-100 μT) and the experiment is conducted in a home-made magnetically-shielded-room (MSR). The measurements are performed by the indirect coupling method in which the signal of nuclei precession is indirectly coupled to the SQUID through a tuned copper coil transformer. In such an arrangement, the interferences of applied measurement and polarization field to the SQUID sensor are avoided and the performance of the SQUID is not destroyed. In order to compare the detection sensitivity obtained by using the SQUID with that achieved using a conventional low-noise-amplifier, we perform the measurements using a commercial room temperature amplifier. The results show that in a wide frequency range (~1 kHz-10 kHz) the measurements with the SQUID sensor exhibit a higher signal-to-noise ratio. Further, we discuss the dependence of NMR peak magnitude on measurement frequency. We attribute the reduction of the peak magnitude at high frequency to the increased field inhomogeneity as the measurement field increases. This is verified by compensating the field gradient using three sets of gradient coils.

  16. EMC effect: asymptotic freedom with nuclear targets

    SciTech Connect

    West, G.B.

    1984-01-01

    General features of the EMC effect are discussed within the framework of quantum chromodynamics as expressed via the operator product expansion and asymptotic freedom. These techniques are reviewed with emphasis on the target dependence. 22 references.

  17. RADIATION EFFECTS IN NUCLEAR WASTE MATERIALS

    EPA Science Inventory

    The objective of this multidisciplinary, multi-institutional research effort is to develop a fundamental understanding at the atomic, microscopic, and macroscopic levels of radiation effects in glass and ceramics that provides the underpinning science and models for evaluation an...

  18. Origin of the neutron skin thickness of {sup 208}Pb in nuclear mean-field models

    SciTech Connect

    Centelles, M.; Roca-Maza, X.; Vinas, X.; Warda, M.

    2010-11-15

    We study whether the neutron skin thickness {Delta}r{sub np} of {sup 208}Pb originates from the bulk or from the surface of the nucleon density distributions, according to the mean-field models of nuclear structure, and find that it depends on the stiffness of the nuclear symmetry energy. The bulk contribution to {Delta}r{sub np} arises from an extended sharp radius of neutrons, whereas the surface contribution arises from different widths of the neutron and proton surfaces. Nuclear models where the symmetry energy is stiff, as typical of relativistic models, predict a bulk contribution in {Delta}r{sub np} of {sup 208}Pb about twice as large as the surface contribution. In contrast, models with a soft symmetry energy like common nonrelativistic models predict that {Delta}r{sub np} of {sup 208}Pb is divided similarly into bulk and surface parts. Indeed, if the symmetry energy is supersoft, the surface contribution becomes dominant. We note that the linear correlation of {Delta}r{sub np} of {sup 208}Pb with the density derivative of the nuclear symmetry energy arises from the bulk part of {Delta}r{sub np}. We also note that most models predict a mixed-type (between halo and skin) neutron distribution for {sup 208}Pb. Although the halo-type limit is actually found in the models with a supersoft symmetry energy, the skin-type limit is not supported by any mean-field model. Finally, we compute parity-violating electron scattering in the conditions of the {sup 208}Pb parity radius experiment (PREX) and obtain a pocket formula for the parity-violating asymmetry in terms of the parameters that characterize the shape of the {sup 208}Pb nucleon densities.

  19. Characterisation of radiation field for irradiation of biological samples at nuclear reactor-comparison of twin detector and recombination methods.

    PubMed

    Golnik, N; Gryziński, M A; Kowalska, M; Meronka, K; Tulik, P

    2014-10-01

    Central Laboratory for Radiological Protection is involved in achieving scientific project on biological dosimetry. The project includes irradiation of blood samples in radiation fields of nuclear reactor. A simple facility for irradiation of biological samples has been prepared at horizontal channel of the nuclear reactor MARIA in NCBJ in Poland. The radiation field, composed mainly of gamma radiation and thermal neutrons, has been characterised in terms of tissue kerma using twin-detector technique and recombination chambers. PMID:24366246

  20. Flexibility, Cost Effectiveness Found in Field Contracts.

    ERIC Educational Resources Information Center

    Dorfman, Michael A.; Shoaf, Lawrence G.

    1986-01-01

    A field contract is a two-party contractual agreement intended for procuring material and labor from outside contractors. As used in the Burbank California Unified School District, the field contract allows greater flexibility than the formal bidding process. The type of documents and procedures used in the district are included. (MLF)

  1. Free-field ground motions for the nonproliferation experiment: Preliminary comparisons with nearby nuclear events

    SciTech Connect

    Olsen, K.H.; Peratt, A.L.

    1994-06-01

    Since 1987, we have installed fixed arrays of tri-axial accelerometers in the fire-field near the shot horizons for low-yield ({le} 20 kt) nuclear events in the N-tunnel complex beneath Rainier Mesa. For the Nonproliferation Experiment (NPE) we augmented the array to achieve 23 free-field stations. Goals are: (a) to examine robustness and stability of various free-field source function estimates -- e.g., reduced displacement potentials (RDP) and spectra; (b) to compare close-in with regional estimates to test whether detailed close-in free-field and/or surface ground motion data can improve predictability of regional-teleseismic source functions; (c) to provide experimental data for checking two-dimensional numerical simulations. We report preliminary comparisons between experimental free-field data for NPE (1993) and three nearby nuclear events (MISTY ECHO, 1988; MINERAL QUARRY, 1990; HUNTERS TROPHY, 1992). All four working points are within 1 km of each other in the same wet tuff bed, thus reducing concerns about possible large differences in material properties between widely separated shots. Initial comparison of acceleration and velocity seismograms for the four events reveals: (1) There is a large departure from the spherical symmetry commonly assumed in analytic treatments of source theory; both vertical and tangential components are surprisingly large. (2) All shots show similar first-peak particle-velocity amplitude decay rates suggesting significant attenuation even in the supposedly purely elastic region. (3) Sharp (>20 Hz) arrivals are not observed at tunnel level from near-surface pP reflections or spall-closure sources -- but broadened peaks are seen that suggest more diffuse reflected energy from the surface and from the Paleozoic limestone basement below tunnel level.

  2. 76 FR 55137 - Monitoring the Effectiveness of Maintenance at Nuclear Power Plants

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-06

    ... COMMISSION Monitoring the Effectiveness of Maintenance at Nuclear Power Plants AGENCY: Nuclear Regulatory..., ``Monitoring the Effectiveness of Maintenance at Nuclear Power Plants.'' This guide endorses Revision 4A to... Effectiveness of Maintenance at Nuclear Power Plants,'' which provides methods that are acceptable to the...

  3. Effects of Nuclear Interactions on Accuracy of Space Radiation Transport

    NASA Technical Reports Server (NTRS)

    Lin, Zi-Wei; Barghouty, A. F.

    2005-01-01

    Space radiation risk to astronauts and electronic equipments is one major obstacle in long term human space explorations. Space radiation transport codes have been developed to calculate radiation effects behind materials in human missions to the Moon, Mars or beyond. We study how nuclear fragmentation processes affect the accuracy of predictions from such radiation transport. In particular, we investigate the effects of fragmentation cross sections at different energies on fluxes, dose and dose-equivalent from galactic cosmic rays behind typical shielding materials. These results tell us at what energies nuclear cross sections are the most important for radiation risk evaluations, and how uncertainties in our knowledge about nuclear fragmentations relate to uncertainties in space transport predictions.

  4. Isotropic proton-detected local-field nuclear magnetic resonancein solids

    SciTech Connect

    Havlin, Robert H.; Walls, Jamie D.; Pines, Alexander

    2004-08-04

    A new nuclear magnetic resonance (NMR) method is presented which produces linear, isotropic proton-detected local-field spectra for InS spin systems in powdered samples. The method, HETeronuclear Isotropic Evolution (HETIE), refocuses the anisotropic portion of the heteronuclear dipolar coupling frequencies by evolving the system under a series of specially designed Hamiltonians and evolution pathways. The theory behind HETIE is represented along with experimental studies conducted on a powdered sample of ferrocene, demonstrating the methodology outlined in this paper. Applications of HETIE for structural determination in solid-state NMR are discussed.

  5. New Methodology For Use in Rotating Field Nuclear MagneticResonance

    SciTech Connect

    Jachmann, Rebecca C.

    2007-05-18

    High-resolution NMR spectra of samples with anisotropicbroadening are simplified to their isotropic spectra by fast rotation ofthe sample at the magic angle 54.7 circ. This dissertation concerns thedevelopment of novel Nuclear Magnetic Resonance (NMR) methodologies basedwhich would rotate the magnetic field instead of the sample, rotatingfield NMR. It provides an over of the NMR concepts, procedures, andexperiments needed to understand the methodologies that will be used forrotating field NMR. A simple two-dimensional shimming method based onharmonic corrector rings which can provide arbitrary multiple ordershimming corrections were developed for rotating field systems, but couldbe used in shimming other systems as well. Those results demonstrate, forexample, that quadrupolar order shimming improves the linewidth by up toan order of magnitude. An additional order of magnitude reduction is inprinciple achievable by utilizing this shimming method for z-gradientcorrection and higher order xy gradients. A specialized pulse sequencefor the rotating field NMR experiment is under development. The pulsesequence allows for spinning away from the magic angle and spinningslower than the anisotropic broadening. This pulse sequence is acombination of the projected magic angle spinning (p-MAS) and magic angleturning (MAT) pulse sequences. This will be useful to rotating field NMRbecause there are limits on how fast a field can be spun and spin at themagic angle is difficult. One of the goals of this project is forrotating field NMR to be used on biological systems. The p-MAS pulsesequence was successfully tested on bovine tissue samples which suggeststhat it will be a viable methodology to use in a rotating field set up. Aside experiment on steering magnetic particle by MRI gradients was alsocarried out. Some movement was seen in these experiment, but for totalcontrol over steering further experiments would need to bedone.

  6. Nuclear Quantum Effects in Different Ice Phases

    NASA Astrophysics Data System (ADS)

    Fernandez-Serra, Marivi; Pamuk, Betul; Allen, Philip B.

    We have previously explained that the anomalous isotope effect in hexagonal ices is liked to the anticorrelation between the covalent OH bond and the hydrogen bond by using the quasiharmonic approximation combined with ab initio density functional theory. In this study, we show that similar physics plays a role in the isotope effect on temperature of the proton-order/disorder phase transition between ice XI and iceIh. By using a van der Waals density functional, we calculate a temperature difference between heavy and light ices of 6 K as compared to the experimental value of 4 K. Furthermore, we extend our study to analyze the zero-point effects in different ice phases and ice-like structures with different densities and crystal structures to understand how this can be linked to the anomalous isotope effect in liquid water. This work is supported by DOE Grants No. DE-FG02-09ER16052, No. DE-SC0003871 (M.V.F.S.), and No. DE-FG02-08ER46550 (P.B.A.) and the grant FIS2012-37549-C05 from the Spanish Ministry of Economy and Competitiveness.

  7. Casimir effect for massive scalar field

    NASA Astrophysics Data System (ADS)

    Mobassem, S.

    2014-10-01

    The energy-momentum tensor is used to introduce the Casimir force of the massive scalar field acting on a nonpenetrating surface. This expression can be used to evaluate the vacuum force by employing the appropriate field operators. To simplify our formalism, we also relate the vacuum force expression to the imaginary part of the Green function via the fluctuation-dissipation theorem and Kubo's formula. This allows one to evaluate the vacuum force without resorting to the process of field quantization. These two approaches are used to calculate the attractive force between two nonpenetrating plates. Special attention is paid to the generalization of the formalism to D+1 spacetime dimensions.

  8. Binary black holes' effects on electromagnetic fields.

    PubMed

    Palenzuela, Carlos; Anderson, Matthew; Lehner, Luis; Liebling, Steven L; Neilsen, David

    2009-08-21

    In addition to producing gravitational waves, the dynamics of a binary black hole system could induce emission of electromagnetic radiation by affecting the behavior of plasmas and electromagnetic fields in their vicinity. We here study how the electromagnetic fields are affected by a pair of orbiting black holes through the merger. In particular, we show how the binary's dynamics induce a variability in possible electromagnetically induced emissions as well as a possible enhancement of electromagnetic fields during the late-merge and merger epochs. These time dependent features will likely leave their imprint in processes generating detectable emissions and can be exploited in the detection of electromagnetic counterparts of gravitational waves. PMID:19792706

  9. Mechanism of nuclear spin-lattice relaxation and its field dependence for ultraslow atomic motion

    SciTech Connect

    Mefed, A. E.

    2008-10-15

    The contribution of ultraslow self-diffusion of polycrystalline benzene molecules to the spin-lattice relaxation of protons is studied as a function of effective magnetic field H{sub 2} in a doubly rotating frame (DRF). Proton relaxation time T{sub 1{rho}}{sub {rho}} is measured by direct recording of NMR in a rotating frame (RF). The effective fields have a 'magic' orientation corresponding to angles arccos(1/{radical}3) in the RF and {pi}/2 in the DRF so that the secular part of the dipole-dipole interactions of protons is suppressed in two orders of perturbation theory, while the nonsecular part becomes predominant. It is found that the diffusion contribution of benzene molecules to proton relaxation time T{sub 1{rho}}{sub {rho}} is a linear function of the square of field H{sub 2} and exhibits all peculiarities typical of the model of strong collisions generalized to only fluctuating nonsecular dipole interactions in fields exceeding the local field. This means that the model can also be employed in the given conditions. It is shown that perfect agreement with such a dependence can also be obtained in the model of weak collisions if we take into account the concept of the locally effective quantization field, whose magnitude and direction are controlled by the vector sum of field H{sub 2}, and the nonsecular local field perpendicular to it.

  10. Historical sketches of Sandia National Laboratories nuclear field testing. Volume 1: Full discussion except for sensitive references

    SciTech Connect

    Banister, J.R.

    1994-10-01

    This report contains historical sketches that cover the major activities of Sandia nuclear field testing, from early atmospheric shots until 1990. It includes a chronological overview followed by more complete discussions of atmospheric, high-altitude, underwater, cratering, and underground nuclear testing. Other activities related to nuclear testing and high-explosive tests are also described. A large number of references are cited for readers who wish to learn more about technical details. Appendices, written by several authors, provide more insight for a variety of special aspects of nuclear testing and related work. Two versions of this history were published: volume 1 has an unlimited distribution, and volume 2 has a limited distribution.

  11. Dynamical effects in the Coulomb expansion following nuclear fragmentation

    SciTech Connect

    Chung, K.C.; Donangelo, R.; Schechter, H.

    1987-09-01

    The effects of the Coulomb expansion on the fragment kinetic energy spectrum for a fragmentating hot nuclear system is investigated. In particular, /sup 12/C-fragment spectra are calculated and compared with those predicted by the uniform expansion approximation. The results indicate that the energy spectra of fragments are quite sensitive to the details of the Coulomb expansion treatment.

  12. Coulomb effects on edge scattering in elastic nuclear collisions

    SciTech Connect

    Silveira, R. da; Leclercq-Willain, Ch.

    2011-04-15

    We present a qualitative analysis of the effects of the Coulomb force on the edge scattering produced in elastic nuclear collisions occurring under strong absorption conditions. This analysis is illustrated with several examples of nucleus-nucleus and antiproton-nucleus elastic scattering.

  13. First evidence of detecting surface nuclear magnetic resonance signals using a compact B-field sensor

    NASA Astrophysics Data System (ADS)

    Davis, Aaron C.; Dlugosch, Raphael; Queitsch, Matthias; Macnae, James C.; Stolz, Ronny; Müller-Petke, Mike

    2014-06-01

    The noninvasive detection and characterization of subsurface aquifer structures demands geophysical techniques. Surface nuclear magnetic resonance (SNMR) is the only technique that is directly sensitive to hydrogen protons and, therefore, allows for unambiguous detection of subsurface water. Traditionally, SNMR utilizes large surface coils for both transmitting excitation pulses and recording the groundwater response. Recorded data are thus a voltage induced by the time derivative of the secondary magnetic field. For the first time, we demonstrate that the secondary magnetic field in a SNMR experiment can be directly detected using a superconducting quantum interference device magnetometer. Conducting measurements at a test site in Germany, we demonstrate not only the ability to detect SNMR signals on the order of femtoTesla but also we are able to satisfy the observed data by inverse modeling. This is expected to open up completely new applications for this exciting technology.

  14. Utilizing Urban Environments for Effective Field Experiences

    NASA Astrophysics Data System (ADS)

    MacAvoy, S. E.; Knee, K.

    2014-12-01

    Research surveys suggest that students are demanding more applied field experiences from their undergraduate environmental science programs. For geoscience educators at liberal arts colleges without field camps, university vehicles, or even geology departments, getting students into the field is especially rewarding - and especially challenging. Here, we present strategies that we have used in courses ranging from introductory environmental science for non-majors, to upper level environmental methods and geology classes. Urban locations provide an opportunity for a different type of local "field-work" than would otherwise be available. In the upper-level undergraduate Environmental Methods class, we relied on a National Park area located a 10-minute walk from campus for most field exercises. Activities included soil analysis, measuring stream flow and water quality parameters, dendrochronology, and aquatic microbe metabolism. In the non-majors class, we make use of our urban location to contrast water quality in parks and highly channelized urban streams. Here we share detailed lesson plans and budgets for field activities that can be completed during a class period of 2.5 hours with a $75 course fee, show how these activities help students gain quantitative competency, and provide student feedback about the classes and activities.

  15. Interaction of Strain and Nuclear Spins in Silicon: Quadrupolar Effects on Ionized Donors

    NASA Astrophysics Data System (ADS)

    Franke, David P.; Hrubesch, Florian M.; Künzl, Markus; Becker, Hans-Werner; Itoh, Kohei M.; Stutzmann, Martin; Hoehne, Felix; Dreher, Lukas; Brandt, Martin S.

    2015-07-01

    The nuclear spins of ionized donors in silicon have become an interesting quantum resource due to their very long coherence times. Their perfect isolation, however, comes at a price, since the absence of the donor electron makes the nuclear spin difficult to control. We demonstrate that the quadrupolar interaction allows us to effectively tune the nuclear magnetic resonance of ionized arsenic donors in silicon via strain and determine the two nonzero elements of the S tensor linking strain and electric field gradients in this material to S11=1.5 ×1022 V /m2 and S44=6 ×1022 V /m2 . We find a stronger benefit of dynamical decoupling on the coherence properties of transitions subject to first-order quadrupole shifts than on those subject to only second-order shifts and discuss applications of quadrupole physics including mechanical driving of magnetic resonance, cooling of mechanical resonators, and strain-mediated spin coupling.

  16. Strong screening effects on resonant nuclear reaction 23Mg (p, γ) 24Al in the surface of magnetars

    NASA Astrophysics Data System (ADS)

    Liu, Jing-Jing

    2016-05-01

    Based on the theory of relativistic superstrong magnetic fields (SMFs), by using the method of Thomas-Fermi-Dirac approximations, we investigate the problem of strong electron screening (SES) in SMFs and the influence of SES on the nuclear reaction of 23Mg (p, γ)24Al. Our calculations show that the nuclear reaction will be markedly effected by the SES in SMFs in the surface of magnetars. Our calculated screening rates can increase two orders of magnitude due to SES in SMFs.

  17. Isotope effects in the harmonic response from hydrogenlike muonic atoms in strong laser fields

    SciTech Connect

    Shahbaz, Atif; Mueller, Carsten; Buervenich, Thomas J.

    2010-07-15

    High-order harmonic generation from hydrogenlike muonic atoms exposed to ultraintense high-frequency laser fields is studied. Systems of low nuclear-charge number Z are considered where a nonrelativistic description applies. By comparing the radiative response for different isotopes, we demonstrate characteristic signatures of the finite nuclear mass and size in the harmonic spectra. In particular, for Z>1, an effective muon charge appears in the Schroedinger equation for the relative particle motion, which influences the position of the harmonic cutoff. Cutoff energies in the million-electron-volt domain can be achieved, offering prospects for the generation of ultrashort coherent {gamma}-ray pulses.

  18. Nuclear Effects in Neutrino Interactions at Low Momentum Transfer

    SciTech Connect

    Miltenberger, Ethan Ryan

    2015-05-01

    This is a study to identify predicted effects of the carbon nucleus environment on neutrino - nucleus interactions with low momentum transfer. A large sample of neutrino interaction data collected by the MINERvA experiment is analyzed to show the distribution of charged hadron energy in a region with low momentum transfer. These distributions reveal a major discrepancy between the data and a popular interaction model with only the simplest Fermi gas nuclear effects. Detailed analysis of systematic uncertainties due to energy scale and resolution can account for only a little of the discrepancy. Two additional nuclear model effects, a suppression/screening effect (RPA), and the addition of a meson exchange current process (MEC), are shown to improve the description of the data.

  19. Effect of topological defects on "nuclear pasta" observables

    NASA Astrophysics Data System (ADS)

    Schneider, A. S.; Berry, D. K.; Caplan, M. E.; Horowitz, C. J.; Lin, Z.

    2016-06-01

    Background: The "pasta" phase of nuclear matter may play an important role in the structure and evolution of neutron stars. Recent works suggest nuclear pasta has a high resistivity which could be explained by the presence of long-lived topological defects. The defects act as impurities that decrease thermal and electrical conductivity of the pasta. Purpose: To quantify how topological defects affect transport properties of nuclear pasta and estimate this effect using an impurity parameter Qimp. Methods: Contrast molecular dynamics simulations of up to 409 600 nucleons arranged in parallel nuclear pasta slabs (perfect pasta) with simulations of pasta slabs connected by topological defects (impure pasta). From these simulations we compare the viscosity and heat conductivity of perfect and impure pasta to obtain an effective impurity parameter Qimp due to the presence of defects. Results: Both the viscosity and thermal conductivity calculated for both perfect and impure pasta are anisotropic, peaking along directions perpendicular to the slabs and reaching a minimum close to zero parallel to them. In our 409 600 nucleon simulation topological defects connecting slabs of pasta reduce both the thermal conductivity and viscosity on average by about 37%. We estimate an effective impurity parameter due to the defects of order Qimp˜30 . Conclusions: Topological defects in the pasta phase of nuclear matter have an effect similar to impurities in a crystal lattice. The irregularities introduced by the defects reduce the thermal and electrical conductivities and the viscosity of the system. This effect can be parametrized by a large impurity parameter Qimp˜30 .

  20. Geomagnetic field effects of the Chelyabinsk meteoroid

    NASA Astrophysics Data System (ADS)

    Chernogor, L. F.

    2014-09-01

    An analysis was conducted of time variations in geomagnetic field components on the day of the Chelyabinsk meteorite event (February 15, 2013) and on control days (February 12 and 16, 2013). The analysis uses the data collected by magnetic observatories in Novosibirsk, Almaty, Kyiv, and Lviv. The distance R from the explosion site to the observatories varies in the range 1200-2700 km. The flyby and explosion of the Chelyabinsk cosmic body is found to have been accompanied by variations mainly in the horizontal component of the geomagnetic field. The variations are quasi-periodic with a period of 30-40 min, an amplitude of 0.5-2 nT for R ≈ 2700-1200 km, respectively, and a duration of 2-3 h. The horizontal velocity of the geomagnetic field disturbances is close to 260-370 m/s. A theoretical model of wave disturbances is proposed. According to the model, wave disturbances in the geomagnetic field are caused (a) by the motion of the gravity wave generated in the atmosphere by the falling space body and (b) by traveling ionospheric disturbances, which modulate the ionospheric current at dynamo altitudes. The calculated amplitudes of the wave disturbances are 0.6-1.8 nT for R ≈ 2700-1200 km, respectively. The estimates are in good agreement with the observational data. Disturbances in the geomagnetic field level (geomagnetic pulsations) in the period range 1-1000 s are negligible (less than 1 nT).

  1. The longest illness. Effects of nuclear war in children

    SciTech Connect

    Kappy, M.S.

    1984-03-01

    The destruction of civilization that would follow a nuclear war would render any disaster ever recorded insignificant. Millions of people would perish during the first few hours, and many more would die in the months to come. Survival would exist only in the strictest sense of the word, since societal disorganization, famine, drought, darkness, and nuclear winter would envelope the earth. The comparative frailty of children and their dependence on adults would render them most susceptible to the acute effects of a nuclear holocaust. Furthermore, studies of the Hiroshima and Nagasaki, Japan bombings showed a disproportionate propensity for children to experience leukemias and other cancers years after the bombings. There were also great increases in perinatal deaths and cases of microcephaly and retardation in children exposed in utero to the bombs. In the event that there are future generations after a nuclear war, the issue of heritable genetic effects will become important. Suggestions of permanent genetic damage are emerging from the Hiroshima and Nagasaki studies. By comparison, the genetic effects of modern weaponry will be incalculable.

  2. Rapid measurements of heterogeneity in sandstones using low-field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Mitchell, Jonathan

    2014-03-01

    Sandstone rocks can contain microscopic variations in composition that complicate interpretation of nuclear magnetic resonance (NMR) relaxation time measurements. In this work, methods for assessing the degree of sample heterogeneity are demonstrated in three sandstones. A two-dimensional T1-Δχapp correlation (where Δχapp is the apparent solid/liquid magnetic susceptibility contrast) reveals the microscopic heterogeneity in composition, whilst a spatially resolved T1 profile reveals the macroscopic structural heterogeneity. To perform these measurements efficiently, a rapid measure of longitudinal T1 relaxation time has been implemented on a low-field NMR spectrometer with a magnetic field strength B0=0.3 T. The “double-shot” T1 pulse sequence is appropriate for analysis of porous materials in general. Example relaxation time distributions are presented for doped water phantoms to validate the method. The acquisition time of the double-shot T1 sequence is equivalent to the single-shot Carr-Purcell Meiboom-Gill (CPMG) sequence used routinely in petrophysics to measure transverse T2 relaxation. Rapid T1 measurements enable practical studies of core plugs at magnetic field strengths previously considered inappropriate, as T1 is independent of molecular diffusion through pore-scale (internal) magnetic field gradients.

  3. Least Squares Magnetic-Field Optimization for Portable Nuclear Magnetic Resonance Magnet Design

    SciTech Connect

    Paulsen, Jeffrey L; Franck, John; Demas, Vasiliki; Bouchard, Louis-S.

    2008-03-27

    Single-sided and mobile nuclear magnetic resonance (NMR) sensors have the advantages of portability, low cost, and low power consumption compared to conventional high-field NMR and magnetic resonance imaging (MRI) systems. We present fast, flexible, and easy-to-implement target field algorithms for mobile NMR and MRI magnet design. The optimization finds a global optimum ina cost function that minimizes the error in the target magnetic field in the sense of least squares. When the technique is tested on a ring array of permanent-magnet elements, the solution matches the classical dipole Halbach solution. For a single-sided handheld NMR sensor, the algorithm yields a 640 G field homogeneous to 16 100 ppm across a 1.9 cc volume located 1.5 cm above the top of the magnets and homogeneous to 32 200 ppm over a 7.6 cc volume. This regime is adequate for MRI applications. We demonstrate that the homogeneous region can be continuously moved away from the sensor by rotating magnet rod elements, opening the way for NMR sensors with adjustable"sensitive volumes."

  4. Quantum statistical correlations in thermal field theories: Boundary effective theory

    SciTech Connect

    Bessa, A.; Brandt, F. T.; Carvalho, C. A. A. de; Fraga, E. S.

    2010-09-15

    We show that the one-loop effective action at finite temperature for a scalar field with quartic interaction has the same renormalized expression as at zero temperature if written in terms of a certain classical field {phi}{sub c}, and if we trade free propagators at zero temperature for their finite-temperature counterparts. The result follows if we write the partition function as an integral over field eigenstates (boundary fields) of the density matrix element in the functional Schroedinger field representation, and perform a semiclassical expansion in two steps: first, we integrate around the saddle point for fixed boundary fields, which is the classical field {phi}{sub c}, a functional of the boundary fields; then, we perform a saddle-point integration over the boundary fields, whose correlations characterize the thermal properties of the system. This procedure provides a dimensionally reduced effective theory for the thermal system. We calculate the two-point correlation as an example.

  5. Coulomb effects in low-energy nuclear fragmentation

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Chun, Sang Y.; Badavi, Francis F.; John, Sarah

    1993-01-01

    Early versions of the Langley nuclear fragmentation code NUCFRAG (and a publicly released version called HZEFRG1) assumed straight-line trajectories throughout the interaction. As a consequence, NUCFRAG and HZEFRG1 give unrealistic cross sections for large mass removal from the projectile and target at low energies. A correction for the distortion of the trajectory by the nuclear Coulomb fields is used to derive fragmentation cross sections. A simple energy-loss term is applied to estimate the energy downshifts that greatly alter the Coulomb trajectory at low energy. The results, which are far more realistic than prior versions of the code, should provide the data base for future transport calculations. The systematic behavior of charge-removal cross sections compares favorably with results from low-energy experiments.

  6. Ram pressure stripping in elliptical galaxies - II. Magnetic field effects

    NASA Astrophysics Data System (ADS)

    Shin, Min-Su; Ruszkowski, Mateusz

    2014-12-01

    We investigate the effects of magnetic fields and turbulence on ram pressure stripping in elliptical galaxies using ideal magnetohydrodynamic simulations. We consider weakly magnetized interstellar medium (ISM) characterized by subsonic turbulence, and two orientations of the magnetic fields in the intracluster medium (ICM) - parallel and perpendicular to the direction of the galaxy motion through the ICM. While the stronger turbulence enhances the ram pressure stripping mass-loss, the magnetic fields tend to suppress the stripping rates, and the suppression is stronger for parallel fields. However, the effect of magnetic fields on the mass stripping rate is mild. Nevertheless, the morphology of the stripping tails depends significantly on the direction of the ICM magnetic field. The effect of the magnetic field geometry on the tail morphology is much stronger than that of the level of the ISM turbulence. The tail has a highly collimated shape for parallel fields, while it has a sheet-like morphology in the plane of the ICM magnetic field for perpendicular fields. The magnetic field in the tail is amplified irrespectively of the orientation of the ICM field. More strongly magnetized regions in the ram pressure stripping tails are expected to have systematically higher metallicity due to the strong concentration of the stripped ISM than the less magnetized regions. Strong dependence of the morphology of the stripped ISM on the magnetic field could potentially be used to constrain the relative orientation of the ram pressure direction and the dominant component of the ICM magnetic field.

  7. Field-effect transistors (2nd revised and enlarged edition)

    NASA Astrophysics Data System (ADS)

    Bocharov, L. N.

    The design, principle of operation, and principal technical characteristics of field-effect transistors produced in the USSR are described. Problems related to the use of field-effect transistors in various radioelectronic devices are examined, and tables of parameters and mean statistical characteristics are presented for the main types of field-effect transistors. Methods for calculating various circuit components are discussed and illustrated by numerical examples.

  8. Non-Abellian field dynamics in the early stage of ultrarelativistic nuclear collisions

    SciTech Connect

    Rischke, D.H.

    1997-09-22

    It was argued that the gluon field of a large, ultrarelativistic nucleus can be considered as a classical field for small values of the longitudinal momentum fraction x and on transverse momentum scales {Lambda}{sup 2}{sub QCD} << k{sup 2}{perpendicular} << {mu}{sup 2}, where {mu}{sup 2} is the transverse area density of color charges. The authors estimated {mu} {approx} 0.4 GeV for collisions of Au-nuclei at RHIC energies. Based on this argument, the gluon field produced in a collision of two ultrarelativistic nuclei is computed perturbatively by solving the classical Yang-Mills equations order by order in the strong coupling constant g. It is shown that to first order in g, the spectrum of produced gluons is identical to that obtained in a perturbative quantum calculation of gluon Bremsstrahlung. It is also identical with that of a coherent quantum state generated by independent collisions between the (classical) color charges in the two nuclei. The perturbative solution is unstable under perturbations. The instabilities arise from the non-Abelian terms in the equations of motion for the gluon field, which enter only at higher order in the perturbative solution scheme. The decay rate of the perturbative solution is shown to be of order {mu}. Since the non-Abelian terms describe the self-interaction of the produced gluon field, and since such interactions lead to thermalization, the decay rate provides an estimate for the thermalization time scale of classical color fields in ultrarelativistic nuclear collisions. For Au-nuclei, this time scale is therefore of order 0.5 fm/c, in agreement with results for the kinetic thermalization time scale.

  9. Tritium β decay in chiral effective field theory

    DOE PAGESBeta

    Baroni, A.; Girlanda, L.; Kievsky, A.; Marcucci, L. E.; Schiavilla, R.; Viviani, M.

    2016-08-18

    We evaluate the Fermi and Gamow-Teller (GT) matrix elements in tritiummore » $$\\beta$$-decay by including in the charge-changing weak current the corrections up to one loop recently derived in nuclear chiral effective field theory ($$\\chi$$ EFT). The trinucleon wave functions are obtained from hyperspherical-harmonics solutions of the Schroedinger equation with two- and three-nucleon potentials corresponding to either $$\\chi$$ EFT (the N3LO/N2LO combination) or meson-exchange phenomenology (the AV18/UIX combination). We find that contributions due to loop corrections in the axial current are, in relative terms, as large as (and in some cases, dominate) those from one-pion exchange, which nominally occur at lower order in the power counting. Furthermore, we also provide values for the low-energy constants multiplying the contact axial current and three-nucleon potential, required to reproduce the experimental GT matrix element and trinucleon binding energies in the N3LO/N2LO and AV18/UIX calculations.« less

  10. Global effects in quaternionic quantum field theory

    NASA Astrophysics Data System (ADS)

    Brumby, S. P.; Joshi, G. C.

    1996-12-01

    We present some striking global consequences of a model quaternionic quantum field theory which is locally complex. We show how making the quaternionic structure a dynamical quantity naturally leads to the prediction of cosmic strings and nonbaryonic hot dark matter candidates.

  11. Effect of Coulomb screening length on nuclear "pasta" simulations

    NASA Astrophysics Data System (ADS)

    Alcain, P. N.; Giménez Molinelli, P. A.; Nichols, J. I.; Dorso, C. O.

    2014-05-01

    We study the role of the effective Coulomb interaction strength and length on the dynamics of nucleons in conditions according to those in a neutron star's crust. Calculations were made with a semiclassical molecular dynamics model, studying isospin symmetric matter at subsaturation densities and low temperatures. The electrostatic interaction between protons is included as a screened Coulomb potential in the spirit of the Thomas-Fermi approximation, but the screening length is artificially varied to explore its effect on the formation of the nonhomogeneous nuclear structures known as "nuclear pasta." As the screening length increases, we can see a transition from a one-per-cell pasta regime (due exclusively to finite-size effects) to a more appealing multiple pasta per simulation box. This qualitative difference in the structure of neutron star matter at low temperatures shows that special caution should be taken when the screening length is estimated for numerical simulations.

  12. Dissipative Effects in the Effective Field Theory of Inflation

    SciTech Connect

    Lopez Nacir, Diana; Porto, Rafael A.; Senatore, Leonardo; Zaldarriaga, Matias; /Princeton, Inst. Advanced Study

    2012-09-14

    We generalize the effective field theory of single clock inflation to include dissipative effects. Working in unitary gauge we couple a set of composite operators, {Omicron}{sub {mu}{nu}}..., in the effective action which is constrained solely by invariance under time-dependent spatial diffeomorphisms. We restrict ourselves to situations where the degrees of freedom responsible for dissipation do not contribute to the density perturbations at late time. The dynamics of the perturbations is then modified by the appearance of 'friction' and noise terms, and assuming certain locality properties for the Green's functions of these composite operators, we show that there is a regime characterized by a large friction term {gamma} >> H in which the {zeta}-correlators are dominated by the noise and the power spectrum can be significantly enhanced. We also compute the three point function <{zeta}{zeta}{zeta}> for a wide class of models and discuss under which circumstances large friction leads to an increased level of non-Gaussianities. In particular, under our assumptions, we show that strong dissipation together with the required non-linear realization of the symmetries implies |f{sub NL}| {approx} {gamma}/c{sub s}{sup 2} H >> 1. As a paradigmatic example we work out a variation of the 'trapped inflation' scenario with local response functions and perform the matching with our effective theory. A detection of the generic type of signatures that result from incorporating dissipative effects during inflation, as we describe here, would teach us about the dynamics of the early universe and also extend the parameter space of inflationary models.

  13. Dissipative effects in the effective field theory of inflation

    NASA Astrophysics Data System (ADS)

    Nacir, Diana López; Porto, Rafael A.; Senatore, Leonardo; Zaldarriaga, Matias

    2012-01-01

    We generalize the effective field theory of single clock inflation to include dissipative effects. Working in unitary gauge we couple a set of composite operators, {mathcal{O}_{{μ ν }}}_{ ldots } , in the effective action which is constrained solely by invariance under time-dependent spatial diffeomorphisms. We restrict ourselves to situations where the degrees of freedom responsible for dissipation do not contribute to the density perturbations at late time. The dynamics of the perturbations is then modified by the appearance of `friction' and noise terms, and assuming certain locality properties for the Green's functions of these composite operators, we show that there is a regime characterized by a large friction term γ ≫ H in which the ζ-correlators are dominated by the noise and the power spectrum can be significantly enhanced. We also compute the three point function <ζζζ> for a wide class of models and discuss under which circumstances large friction leads to an increased level of non-Gaussianities. In particular, under our assumptions, we show that strong dissipation together with the required non-linear realization of the symmetries implies left| {{f_{text{NL}}}} right|˜ γ /{c_s^2H} ≫ 1 . As a paradigmatic example we work out a variation of the `trapped inflation' scenario with local response functions and perform the matching with our effective theory. A detection of the generic type of signatures that result from incorporating dissipative effects during inflation, as we describe here, would teach us about the dynamics of the early universe and also extend the parameter space of inflationary models.

  14. MOA: Magnetic Field Oscillating Amplified Thruster and its Application for Nuclear Electric and Thermal Propulsion

    SciTech Connect

    Frischauf, Norbert; Hettmer, Manfred; Grassauer, Andreas; Bartusch, Tobias; Koudelka, Otto

    2006-07-01

    More than 60 years after the later Nobel laureate Hannes Alfven had published a letter stating that oscillating magnetic fields can accelerate ionised matter via magneto-hydrodynamic interactions in a wave like fashion, the technical implementation of Alfven waves for propulsive purposes has been proposed, patented and examined for the first time by a group of inventors. The name of the concept, utilising Alfven waves to accelerate ionised matter for propulsive purposes, is MOA - Magnetic field Oscillating Amplified thruster. Alfven waves are generated by making use of two coils, one being permanently powered and serving also as magnetic nozzle, the other one being switched on and off in a cyclic way, deforming the field lines of the overall system. It is this deformation that generates Alfven waves, which are in the next step used to transport and compress the propulsive medium, in theory leading to a propulsion system with a much higher performance than any other electric propulsion system. Based on computer simulations, which were conducted to get a first estimate on the performance of the system, MOA is a highly flexible propulsion system, whose performance parameters might easily be adapted, by changing the mass flow and/or the power level. As such the system is capable to deliver a maximum specific impulse of 13116 s (12.87 mN) at a power level of 11.16 kW, using Xe as propellant, but can also be attuned to provide a thrust of 236.5 mN (2411 s) at 6.15 kW of power. While space propulsion is expected to be the prime application for MOA and is supported by numerous applications such as Solar and/or Nuclear Electric Propulsion or even as an 'afterburner system' for Nuclear Thermal Propulsion, other terrestrial applications can be thought of as well, making the system highly suited for a common space-terrestrial application research and utilisation strategy. (authors)

  15. Field site investigation: Effect of mine seismicity on groundwater hydrology

    SciTech Connect

    Ofoegbu, G.I.; Hsiung, S.; Chowdhury, A.H.; Philip, J.

    1995-04-01

    The results of a field investigation on the groundwater-hydrologic effect of mining-induced earthquakes are presented in this report. The investigation was conducted at the Lucky Friday Mine, a silver-lead-zinc mine in the Coeur d`Alene Mining District of Idaho. The groundwater pressure in sections of three fracture zones beneath the water table was monitored over a 24-mo period. The fracture zones were accessed through a 360-m-long inclined borehole, drilled from the 5,700 level station of the mine. The magnitude, source location, and associated ground motions of mining-induced seismic events were also monitored during the same period, using an existing seismic instrumentation network for the mine, augmented with additional instruments installed specifically for the project by the center for Nuclear Waste Regulatory Analyses (CNWRA). More than 50 seismic events of Richter magnitude 1.0 or larger occurred during the monitoring period. Several of these events caused the groundwater pressure to increase, whereas a few caused it to decrease. Generally, the groundwater pressure increased as the magnitude of seismic event increased; for an event of a given magnitude, the groundwater pressure increased by a smaller amount as the distance of the observation point from the source of the event increased. The data was examined using regression analysis. Based on these results, it is suggested that the effect of earthquakes on groundwater flow may be better understood through mechanistic modeling. The mechanical processes and material behavior that would need to be incorporated in such a model are examined. They include a description of the effect of stress change on the permeability and water storage capacity of a fracture rock mass; transient fluid flow; and the generation and transmission of seismic waves through the rock mass.

  16. Field Effects in the CNS Play Functional Roles

    PubMed Central

    Weiss, Shennan A.; Faber, Donald S.

    2010-01-01

    An endogenous electrical field effect, i.e., ephaptic transmission, occurs when an electric field associated with activity occurring in one neuron polarizes the membrane of another neuron. It is well established that field effects occur during pathological conditions, such as epilepsy, but less clear if they play a functional role in the healthy brain. Here, we describe the principles of field effect interactions, discuss identified field effects in diverse brain structures from the teleost Mauthner cell to the mammalian cortex, and speculate on the function of these interactions. Recent evidence supports that relatively weak endogenous and exogenous field effects in laminar structures reach significance because they are amplified by network interactions. Such interactions may be important in rhythmogenesis for the cortical slow wave and hippocampal sharp wave–ripple, and also during transcranial stimulation. PMID:20508749

  17. Effect of the Fukushima nuclear accident on the risk perception of residents near a nuclear power plant in China

    PubMed Central

    Huang, Lei; Zhou, Ying; Han, Yuting; Hammitt, James K.; Bi, Jun; Liu, Yang

    2013-01-01

    We assessed the influence of the Fukushima nuclear accident (FNA) on the Chinese public’s attitude and acceptance of nuclear power plants in China. Two surveys (before and after the FNA) were administered to separate subsamples of residents near the Tianwan nuclear power plant in Lianyungang, China. A structural equation model was constructed to describe the public acceptance of nuclear power and four risk perception factors: knowledge, perceived risk, benefit, and trust. Regression analysis was conducted to estimate the relationship between acceptance of nuclear power and the risk perception factors while controlling for demographic variables. Meanwhile, we assessed the median public acceptable frequencies for three levels of nuclear events. The FNA had a significant impact on risk perception of the Chinese public, especially on the factor of perceived risk, which increased from limited risk to great risk. Public acceptance of nuclear power decreased significantly after the FNA. The most sensitive groups include females, those not in public service, those with lower income, and those living close to the Tianwan nuclear power plant. Fifty percent of the survey respondents considered it acceptable to have a nuclear anomaly no more than once in 50 y. For nuclear incidents and serious incidents, the frequencies are once in 100 y and 150 y, respectively. The change in risk perception and acceptance may be attributed to the FNA. Decreased acceptance of nuclear power after the FNA among the Chinese public creates additional obstacles to further development of nuclear power in China and require effective communication strategies. PMID:24248341

  18. Characterisation of mixed neutron photon workplace fields at nuclear facilities by spectrometry (energy and direction) within the EVIDOS project.

    PubMed

    Luszik-Bhadra, M; Bartlett, D; Bolognese-Milsztajn, T; Boschung, M; Coeck, M; Curzio, G; d'Errico, F; Fiechtner, A; Lacoste, V; Lindborg, L; Reginatto, M; Schuhmacher, H; Tanner, R; Vanhavere, F

    2007-01-01

    Within the EC project EVIDOS, 17 different mixed neutron-photon workplace fields at nuclear facilities (boiling water reactor, pressurised water reactor, research reactor, fuel processing, storage of spent fuel) were characterised using conventional Bonner sphere spectrometry and newly developed direction spectrometers. The results of the analysis, using Bayesian parameter estimation methods and different unfolding codes, some of them especially adapted to simultaneously unfold energy and direction distributions of the neutron fluence, showed that neutron spectra differed strongly at the different places, both in energy and direction distribution. The implication of the results for the determination of reference values for radiation protection quantities (ambient dose equivalent, personal dose equivalent and effective dose) and the related uncertainties are discussed. PMID:17890781

  19. Investigations of ``soft-landed'' Cd surface atoms via nuclear methods: hyperfine-field sign determination

    NASA Astrophysics Data System (ADS)

    Manzhur, Y.; Zeitz, W.-D.; Prandolini, M. J.; Brewer, W. D.; Imielski, P.; Schubert, J.; Johnston, K.

    2007-10-01

    Using refined preparation techniques, cadmium guest atoms have been positioned at different sites on the surfaces of nickel crystals. The magnetic hyperfine fields and the electric field gradients at the Cd nuclei were measured by time-dependent perturbed angular correlation (TDPAC) spectroscopy of the emitted gamma radiations. By measuring the combined interactions, electric field gradients and magnetic hyperfine fields can be unambiguously attributed to each surface site. The signs of the magnetic hyperfine fields are determined by applying an external magnetic field and choosing the appropriate γ-ray detector configuration. The measured fields correlate with the number of neighbouring host atoms. Band structure calculations confirm this finding and predict magnetic fields for various sp elements from the band structure of the s-like conduction electrons. The quadrupolar interactions are manifestations of the balance in the occupation of the guest p-sublevels. These results provide new information on the structure and formation of electronic configurations of sp elements in different local environments and will contribute to understanding electronic effects on surfaces.

  20. Effect of tidal fields on star clusters

    NASA Technical Reports Server (NTRS)

    Chernoff, David; Weinberg, Martin

    1991-01-01

    We follow the dynamical evolution of a star cluster in a galactic tidal field using a restricted N-body code. We find large asymmetric distortions in the outer profile of the cluster in the first 10 or so crossing times as material is lost. Prograde stars escape preferentially and establish a potentially observable retrograde rotation in the halo. We present the rate of particle loss and compare with the prescription proposed by Lee and Ostriker (1987).

  1. Gauge anomalies in an effective field theory

    SciTech Connect

    Preskill, J. )

    1991-09-01

    A four-dimensional gauge theory with anomalous fermion content can be consistently quantized, provided that at least some gauge fields are permitted to have nonvanishing masses. Such a theory is nonrenormalizable; there is a maximal value of the ultraviolet cutoff {Lambda}, beyond which the locality of the theory breaks down. The maximal {Lambda} can be estimated in perturbation theory and has a qualitatively different character in Abelian and non-Abelian anomalous gauge theories.

  2. Electromagnetic Field Effects in Semiconductor Crystal Growth

    NASA Technical Reports Server (NTRS)

    Dulikravich, George S.

    1996-01-01

    This proposed two-year research project was to involve development of an analytical model, a numerical algorithm for its integration, and a software for the analysis of a solidification process under the influence of electric and magnetic fields in microgravity. Due to the complexity of the analytical model that was developed and its boundary conditions, only a preliminary version of the numerical algorithm was developed while the development of the software package was not completed.

  3. Effect of zero magnetic field on cardiovascular system and microcirculation

    NASA Astrophysics Data System (ADS)

    Gurfinkel, Yu. I.; At'kov, O. Yu.; Vasin, A. L.; Breus, T. K.; Sasonko, M. L.; Pishchalnikov, R. Yu.

    2016-02-01

    The effects of zero magnetic field conditions on cardiovascular system of healthy adults have been studied. In order to generate zero magnetic field, the facility for magnetic fields modeling "ARFA" has been used. Parameters of the capillary blood flow, blood pressure, and the electrocardiogram (ECG) monitoring were measured during the study. All subjects were tested twice: in zero magnetic field and, for comparison, in sham condition. The obtained results during 60 minutes of zero magnetic field exposure demonstrate a clear effect on cardiovascular system and microcirculation. The results of our experiments can be used in studies of long-term stay in hypo-magnetic conditions during interplanetary missions.

  4. Effect of zero magnetic field on cardiovascular system and microcirculation.

    PubMed

    Gurfinkel, Yu I; At'kov, O Yu; Vasin, A L; Breus, T K; Sasonko, M L; Pishchalnikov, R Yu

    2016-02-01

    The effects of zero magnetic field conditions on cardiovascular system of healthy adults have been studied. In order to generate zero magnetic field, the facility for magnetic fields modeling "ARFA" has been used. Parameters of the capillary blood flow, blood pressure, and the electrocardiogram (ECG) monitoring were measured during the study. All subjects were tested twice: in zero magnetic field and, for comparison, in sham condition. The obtained results during 60 minutes of zero magnetic field exposure demonstrate a clear effect on cardiovascular system and microcirculation. The results of our experiments can be used in studies of long-term stay in hypo-magnetic conditions during interplanetary missions. PMID:26948007

  5. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    NASA Astrophysics Data System (ADS)

    Cho, Herman

    2016-09-01

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3 / 2 , 5 / 2 , 7 / 2, and 9 / 2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  6. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    DOE PAGESBeta

    Cho, Herman

    2016-02-28

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2,5/2,7/2, and 9/2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Furthermore, applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  7. Hanle Effect Diagnostics of the Coronal Magnetic Field: A Test Using Realistic Magnetic Field Configurations

    NASA Astrophysics Data System (ADS)

    Raouafi, N.-E.; Solanki, S. K.; Wiegelmann, T.

    2009-06-01

    Our understanding of coronal phenomena, such as coronal plasma thermodynamics, faces a major handicap caused by missing coronal magnetic field measurements. Several lines in the UV wavelength range present suitable sensitivity to determine the coronal magnetic field via the Hanle effect. The latter is a largely unexplored diagnostic of coronal magnetic fields with a very high potential. Here we study the magnitude of the Hanle-effect signal to be expected outside the solar limb due to the Hanle effect in polarized radiation from the H I Lyα and β lines, which are among the brightest lines in the off-limb coronal FUV spectrum. For this purpose we use a magnetic field structure obtained by extrapolating the magnetic field starting from photospheric magnetograms. The diagnostic potential of these lines for determining the coronal magnetic field, as well as their limitations are studied. We show that these lines, in particular H I Lyβ, are useful for such measurements.

  8. Collisional effects on Rayleigh-Taylor-induced magnetic fields

    SciTech Connect

    Manuel, M. J.-E.; Flaig, M.; Plewa, T.; Li, C. K.; Séguin, F. H.; Frenje, J. A.; Casey, D. T.; Petrasso, R. D.; Hu, S. X.; Betti, R.; Hager, J.; Meyerhofer, D. D.; Smalyuk, V.

    2015-05-15

    Magnetic-field generation from the Rayleigh-Taylor (RT) instability was predicted more than 30 years ago, though experimental measurements of this phenomenon have only occurred in the past few years. These pioneering observations demonstrated that collisional effects are important to B-field evolution. To produce fields of a measurable strength, high-intensity lasers irradiate solid targets to generate the nonaligned temperature and density gradients required for B-field generation. The ablation process naturally generates an unstable system where RT-induced magnetic fields form. Field strengths inferred from monoenergetic-proton radiographs indicate that in the ablation region diffusive effects caused by finite plasma resistivity are not negligible. Results from the first proof-of-existence experiments are reviewed and the role of collisional effects on B-field evolution is discussed in detail.

  9. Nuclear effects in Drell-Yan production at the LHC

    NASA Astrophysics Data System (ADS)

    Krelina, M.; Basso, E.; Goncalves, V. P.; Nemchik, J.; Pasechnik, R.

    2016-07-01

    Using the color dipole formalism we study production of Drell-Yan (DY) pairs in proton-nucleus interactions in the kinematic region corresponding to LHC experiments. Lepton pairs produced in a hard scattering are not accompanied with any final state interactions leading to either energy loss or absorption. Consequently, dileptons may serve as more efficient and cleaner probes for the onset of nuclear effects than nclusive hadron production. We perform a systematic analysis of these effects in production of Drell-Yan pairs in pPb interaction at the LHC. We present predictions for the nuclear suppression as a function of the dilepton transverse momentum, rapidity and invariant mass which can be verified by the LHC measurements. We found that a strong nuclear suppression can be interpreted as an effective energy loss proportional to the initial energy universally induced by multiple initial state interactions. In addition, we study a contribution of coherent effects associated with the gluon shadowing affecting the observables predominantly at small and medium-high transverse momenta.

  10. Planar Hall effect bridge magnetic field sensors

    SciTech Connect

    Henriksen, A. D.; Dalslet, B. T.; Skieller, D. H.; Lee, K. H.; Okkels, F.; Hansen, M. F.

    2010-07-05

    Until now, the planar Hall effect has been studied in samples with cross-shaped Hall geometry. We demonstrate theoretically and experimentally that the planar Hall effect can be observed for an exchange-biased ferromagnetic material in a Wheatstone bridge topology and that the sensor signal can be significantly enhanced by a geometric factor. For the samples in the present study, we demonstrate an enhancement of the sensor output by a factor of about 100 compared to cross-shaped sensors. The presented construction opens a new design and application area of the planar Hall effect, which we term planar Hall effect bridge sensors.

  11. Effective field theory: A modern approach to anomalous couplings

    SciTech Connect

    Degrande, Céline; Centre for Particle Physics and Phenomenology , Université Catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve ; Greiner, Nicolas; Max-Planck-Institut für Physik, Föhringer Ring 6, 80805 München ; Kilian, Wolfgang; University of Siegen, Fachbereich Physik, D-57068 Siegen ; Mattelaer, Olivier; Mebane, Harrison; Stelzer, Tim; Willenbrock, Scott; Zhang, Cen; Centre for Particle Physics and Phenomenology , Université Catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve

    2013-08-15

    We advocate an effective field theory approach to anomalous couplings. The effective field theory approach is the natural way to extend the standard model such that the gauge symmetries are respected. It is general enough to capture any physics beyond the standard model, yet also provides guidance as to the most likely place to see the effects of new physics. The effective field theory approach also clarifies that one need not be concerned with the violation of unitarity in scattering processes at high energy. We apply these ideas to pair production of electroweak vector bosons. -- Highlights: •We discuss the advantages of effective field theories compared to anomalous couplings. •We show that one need not be concerned with unitarity violation at high energy. •We discuss the application of effective field theory to weak boson physics.

  12. Low-field nuclear magnetic resonance for the in vivo study of water content in trees.

    PubMed

    Yoder, Jacob; Malone, Michael W; Espy, Michelle A; Sevanto, Sanna

    2014-09-01

    Nuclear magnetic resonance (NMR) and magnetic resonance imaging have long been used to study water content in plants. Approaches have been primarily based on systems using large magnetic fields (~1 T) to obtain NMR signals with good signal-to-noise. This is because the NMR signal scales approximately with the magnetic field strength squared. However, there are also limits to this approach in terms of realistic physiological configuration or those imposed by the size and cost of the magnet. Here we have taken a different approach--keeping the magnetic field low to produce a very light and inexpensive system, suitable for bulk water measurements on trees less than 5 cm in diameter, which could easily be duplicated to measure on many trees or from multiple parts of the same tree. Using this system we have shown sensitivity to water content in trees and their cuttings and observed a diurnal signal variation in tree water content in a greenhouse. We also demonstrate that, with calibration and modeling of the thermal polarization, the system is reliable under significant temperature variation. PMID:25273775

  13. Field cage development for a time-projection chamber to constrain the nuclear symmetry energy

    NASA Astrophysics Data System (ADS)

    Estee, J.; Barney, J.; Chajecki, Z.; Famiano, M.; Dunn, J.; Lu, F.; Lynch, W. G.; McIntosh, A. B.; Isobe, T.; Murakami, T.; Sakurai, H.; Shane, R.; Taketani, A.; Tangwancharoen, S.; Tsang, M. B.; Yennello, S.

    2012-10-01

    The SAMURAI time-projection chamber (sTPC) is being developed for use in the dipole magnet of the newly-commissioned SAMURAI spectrometer at the RIBF facility in Japan. The main scientific objective of the sTPC is to provide constraints on the nuclear symmetry energy at supra-saturation densities. The TPC allows for tracking and identification of light charged particles such as pions, protons, tritons and ^3He. The sTPC must have a Cartesian geometry to match the symmetry of the dipole magnet. The walls of the field cage (FC) detector volume consist of sections of rigid, two-layer circuit boards. Inside and outside copper strips form decreasing equipotentials via a resistor chain, and create a uniform electric field with a maximum of 400 V/cm. The FC volume is hermetically sealed from the enclosure volume to create an insulation volume which can be filled with dry N2 to inhibit corona discharge. I will be presenting the current status of the design and assembly of the sTPC field cage.

  14. Expected near-field thermal performance for nuclear waste repositories at potential salt sites: Technical report

    SciTech Connect

    McNulty, E.G.

    1987-08-01

    Thermal analyses were made for the environmental assessments of seven potential salt sites for a nuclear waste repository. These analyses predicted that potential repository sites in domal salts located in the Gulf Coast will experience higher temperature than those in bedded salts of Paradox and Palo Duro Basins, mainly because of higher ambient temperatures at depth. The TEMPV5 code, a semi-analytical heat transfer code for finite line sources, calculated temperatures for commercial high-level waste (CHLW) and spent fuel from pressurized-water reactors (SFPWR). Benchmarks with HEATING6, THAC-SIP-3D, STEALTH, and SPECTROM-41 showed that TEMPV5 agreed closely in the very near field around the waste package and approximately in the near-field and far-field regions of the repository. The analyses used site-specific thermal conductivities that were increased by 40% to compensate for reductions caused by testing technique, salt impurities, and other heterogeneities, and sampling disturbance. Analyses showed peak salt temperatures of 236/sup 0/C (CHLW) and 134/sup 0/C (SFPWR) for the bedded salt and 296/sup 0/C (CHLW) and 180/sup 0/C (SFPWR) for the domal salt. Analyses with uncorrected laboratory thermal conductivities would increase peak salt temperatures by about 120/sup 0/C for CHLW and about 60/sup 0/C for SFPWR. These temperature increases would increase the thermally induced flow of brine and accelerate corrosion of the waste package. 30 refs., 35 figs., 48 tabs.

  15. Low-field nuclear magnetic resonance for the in vivo study of water content in trees

    SciTech Connect

    Yoder, Jacob; Malone, Michael W.; Espy, Michelle A.; Sevanto, Sanna

    2014-09-15

    Nuclear magnetic resonance (NMR) and magnetic resonance imaging have long been used to study water content in plants. Approaches have been primarily based on systems using large magnetic fields (∼1 T) to obtain NMR signals with good signal-to-noise. This is because the NMR signal scales approximately with the magnetic field strength squared. However, there are also limits to this approach in terms of realistic physiological configuration or those imposed by the size and cost of the magnet. Here we have taken a different approach – keeping the magnetic field low to produce a very light and inexpensive system, suitable for bulk water measurements on trees less than 5 cm in diameter, which could easily be duplicated to measure on many trees or from multiple parts of the same tree. Using this system we have shown sensitivity to water content in trees and their cuttings and observed a diurnal signal variation in tree water content in a greenhouse. We also demonstrate that, with calibration and modeling of the thermal polarization, the system is reliable under significant temperature variation.

  16. Macroscopic vacuum effects in an inhomogeneous and nonstationary electromagnetic field

    SciTech Connect

    Gal'tsov, D.V.; Nikitina, N.S.

    1983-04-01

    Macroscopic effects of vacuum polarization by a strong nonuniform and nonstationary fields, which are kinematically forbidden in the case of a uniform magnetic field, are considered. Calculations are perfomed for the deflection of a light beam in the field of a magnetic dipole, for the production of photon pairs by an inclined rotator, and for doubling and modulation of the frequency in scattering of low-frequency electromagnetic waves by the magnetic field of an inclined rotator.

  17. Is the effective field theory of dark energy effective?

    NASA Astrophysics Data System (ADS)

    Linder, Eric V.; Sengör, Gizem; Watson, Scott

    2016-05-01

    The effective field theory of cosmic acceleration systematizes possible contributions to the action, accounting for both dark energy and modifications of gravity. Rather than making model dependent assumptions, it includes all terms, subject to the required symmetries, with four (seven) functions of time for the coefficients. These correspond respectively to the Horndeski and general beyond Horndeski class of theories. We address the question of whether this general systematization is actually effective, i.e. useful in revealing the nature of cosmic acceleration when compared with cosmological data. The answer is no and yes: there is no simple time dependence of the free functions—assumed forms in the literature are poor fits, but one can derive some general characteristics in early and late time limits. For example, we prove that the gravitational slip must restore to general relativity in the de Sitter limit of Horndeski theories, and why it doesn't more generally. We also clarify the relation between the tensor and scalar sectors, and its important relation to observations; in a real sense the expansion history H(z) or dark energy equation of state w(z) is 1/5 or less of the functional information! In addition we discuss the de Sitter, Horndeski, and decoupling limits of the theory utilizing Goldstone techniques.

  18. Magnetic-field-tunable Kondo effect in alkaline-earth cold atoms

    NASA Astrophysics Data System (ADS)

    Isaev, Leonid; Rey, Ana Maria

    2015-05-01

    We study quantum magnetism in strongly interacting fermionic alkaline-earth atoms (AEAs). Due to the decoupling of electronic and nuclear degrees of freedom, AEAs in two lowest electronic states (1S0 and 3P0) obey an accurate SU(N 2 I + 1) symmetry in their two-body collisions (I is the nuclear spin). We consider a system that realizes the simplest SU(2) case (for atoms prepared in two nuclear-spin states) in an optical lattice with two bands: one localized and one itinerant. For the fully filled narrow band (two atoms per lattice site) we demonstrate that an applied magnetic field provides an efficient control of the local ground state degeneracy due to mixing of spin and orbital two-body states. We derive an effective low-energy model that includes this magnetic-field effect as well as atomic interactions in the two optical lattice bands, and show that it exhibits a peculiar phenomenon of a magnetic field-induced Kondo effect, so far observed only in Coulomb blockaded quantum dots. We expect that our results can be tested with ultracold 173 Yb or 87 Sr atoms. Supported by JILA-NSF-PFC-1125844, NSF-PIF-1211914, ARO, AFOSR, AFOSR-MURI.

  19. Removal of earth's magnetic field effect on magnetoelastic resonance sensors by an antisymmetric bias field

    PubMed Central

    Bergmair, Bernhard; Huber, Thomas; Bruckner, Florian; Vogler, Christoph; Suess, Dieter

    2012-01-01

    Magnetoelastic sensors are used in a wide field of wireless sensing applications. The sensing element is a low-cost magnetostrictive ribbon whose resonant frequency depends on the measured quantity. The accuracy of magnetoelastic sensors is limited by the fact that the resonant frequency is also affected by the earth's magnetic field. In this paper we present a technique to minimize this effect by applying an antisymmetric magnetic bias field to the ribbon. The ribbon's response to external perturbation fields was measured and compared to a conventional sensor design. Our results show that the influence of the earth's magnetic field could be reduced by 77%. PMID:23565035

  20. Linewidth-modulated motional Stark effect measurements of internal field structure in low-field configurations

    NASA Astrophysics Data System (ADS)

    Reinecke, E. A.; Fonck, R. J.; Thorson, T. A.

    2001-01-01

    Motional Stark effect measurements of internal field structure in low-field magnetic confinement configurations are considered for both magnitude and direction of the local magnetic field. The amplitude and phase delay of an oscillating spectral linewidth driven by a rotating polarizer provides a means of determining the magnitude and direction of the total field simultaneously while avoiding difficulties of neutral beam energy drift. Photon-noise limit estimates for a diagnostic beam on the low-field PEGASUS toroidal experiment indicate sensitivities of roughly 20 G and 0.2° for the magnitude and direction angle. These values are sufficient to provide significant constraints on magnetic equilibrium reconstructions.

  1. Linewidth-modulated motional Stark effect measurements of internal field structure in low-field configurations

    SciTech Connect

    Reinecke, E. A.; Fonck, R. J.; Thorson, T. A.

    2001-01-01

    Motional Stark effect measurements of internal field structure in low-field magnetic confinement configurations are considered for both magnitude and direction of the local magnetic field. The amplitude and phase delay of an oscillating spectral linewidth driven by a rotating polarizer provides a means of determining the magnitude and direction of the total field simultaneously while avoiding difficulties of neutral beam energy drift. Photon-noise limit estimates for a diagnostic beam on the low-field PEGASUS toroidal experiment indicate sensitivities of roughly 20 G and 0.2{sup o} for the magnitude and direction angle. These values are sufficient to provide significant constraints on magnetic equilibrium reconstructions.

  2. Magnetic field control of the spin Seebeck effect

    NASA Astrophysics Data System (ADS)

    Ritzmann, Ulrike; Hinzke, Denise; Kehlberger, Andreas; Guo, Er-Jia; Kläui, Mathias; Nowak, Ulrich

    2015-11-01

    The origin of the suppression of the longitudinal spin Seebeck effect by applied magnetic fields is studied. We perform numerical simulations of the stochastic Landau-Lifshitz-Gilbert equation of motion for an atomistic spin model and calculate the magnon accumulation in linear temperature gradients for different strengths of applied magnetic fields and different length scales of the temperature gradient. We observe a decrease of the magnon accumulation with increasing magnetic field and we reveal that the origin of this effect is a field dependent change of the frequency distribution of the propagating magnons. With increasing field the magnonic spin currents are reduced due to a suppression of parts of the frequency spectrum. By comparison with measurements of the magnetic field dependent longitudinal spin Seebeck effect in YIG thin films with various thicknesses, we find qualitative agreement between our model and the experimental data, demonstrating the importance of this effect for experimental systems.

  3. Rotatable Small Permanent Magnet Array for Ultra-Low Field Nuclear Magnetic Resonance Instrumentation: A Concept Study

    PubMed Central

    Vegh, Viktor; Reutens, David C.

    2016-01-01

    Object We studied the feasibility of generating the variable magnetic fields required for ultra-low field nuclear magnetic resonance relaxometry with dynamically adjustable permanent magnets. Our motivation was to substitute traditional electromagnets by distributed permanent magnets, increasing system portability. Materials and Methods The finite element method (COMSOL®) was employed for the numerical study of a small permanent magnet array to calculate achievable magnetic field strength, homogeneity, switching time and magnetic forces. A manually operated prototype was simulated and constructed to validate the numerical approach and to verify the generated magnetic field. Results A concentric small permanent magnet array can be used to generate strong sample pre-polarisation and variable measurement fields for ultra-low field relaxometry via simple prescribed magnet rotations. Using the array, it is possible to achieve a pre-polarisation field strength above 100 mT and variable measurement fields ranging from 20–50 μT with 200 ppm absolute field homogeneity within a field-of-view of 5 x 5 x 5 cubic centimetres. Conclusions A dynamic small permanent magnet array can generate multiple highly homogeneous magnetic fields required in ultra-low field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) instruments. This design can significantly reduce the volume and energy requirements of traditional systems based on electromagnets, improving portability considerably. PMID:27271886

  4. Hints on nuclear effects from ArgoNeuT data

    SciTech Connect

    Palamara, Ornella

    2015-05-15

    Initial results from a topological analysis of CC “0 pion” muon neutrino events in LAr collected by the ArgoNeuT experiment on the NuMI LE beam at Fermilab (in the few GeV energy region) are presented and compared with predictions from MC simulations. A new analysis method, based on the reconstruction of exclusive topologies, fully exploiting the LArTPC technique capabilities, is used to analyze the events and study nuclear effects in neutrino interactions on Argon nuclei. Multiple protons accompanying the leading muon and the presence of vertex activity are clearly visible (and measured) in the events. Ratios among rates of different exclusive topologies provide indications of the size of nuclear effects in neutrino-nucleus interactions in LAr.

  5. Heat capacity of water: A signature of nuclear quantum effects

    NASA Astrophysics Data System (ADS)

    Vega, C.; Conde, M. M.; McBride, C.; Abascal, J. L. F.; Noya, E. G.; Ramirez, R.; Sesé, L. M.

    2010-01-01

    In this note we present results for the heat capacity at constant pressure for the TIP4PQ/2005 model, as obtained from path-integral simulations. The model does a rather good job of describing both the heat capacity of ice Ih and of liquid water. Classical simulations using the TIP4P/2005, TIP3P, TIP4P, TIP4P-Ew, simple point charge/extended, and TIP5P models are unable to reproduce the heat capacity of water. Given that classical simulations do not satisfy the third law of thermodynamics, one would expect such a failure at low temperatures. However, it seems that for water, nuclear quantum effects influence the heat capacities all the way up to room temperature. The failure of classical simulations to reproduce Cp points to the necessity of incorporating nuclear quantum effects to describe this property accurately.

  6. Spin field effect transistors with ultracold atoms.

    PubMed

    Vaishnav, J Y; Ruseckas, Julius; Clark, Charles W; Juzeliūnas, Gediminas; Juzelŭnas, Gediminas

    2008-12-31

    We propose a method of constructing cold atom analogs of the spintronic device known as the Datta-Das transistor (DDT), which, despite its seminal conceptual role in spintronics, has never been successfully realized with electrons. We propose two alternative schemes for an atomic DDT, both of which are based on the experimental setup for tripod stimulated Raman adiabatic passage. Both setups involve atomic beams incident on a series of laser fields mimicking the relativistic spin-orbit coupling for electrons that is the operating mechanism of the DDT. PMID:19437649

  7. Spectroscopic study of energetic helium-ion irradiation effects on nuclear graphite tiles

    NASA Astrophysics Data System (ADS)

    Kim, Do Wan; Lee, K. W.; Choi, D. M.; Noh, S. J.; Kim, H. S.; Lee, Cheol Eui

    2016-02-01

    Helium ion-irradiation effects on the nuclear graphite tiles were studied in order to understand the structural modifications and damages that can be produced by fusion reaction in tokamaks. The surface morphological changes due to increasing dose of the irradiation were examined by the field-effect scanning electron microscopy, and X-ray photoelectron spectroscopy elucidated the changes in the shallow surface bonding configurations caused by the energetic irradiation. Raman spectroscopy revealed the structural defects and diamond-like carbon sites that increased with increasing irradiation dose, and the average inter-defect distance was found from the Raman peak intensities as a function of the irradiation dose.

  8. Interplanetary stream magnetism: Kinematic effects. [solar magnetic fields and wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Barouch, E.

    1974-01-01

    The particle density, and the magnetic field intensity and direction are calculated in corotating streams of the solar wind, assuming that the solar wind velocity is constant and radial and that its azimuthal variations are not two rapid. The effects of the radial velocity profile in corotating streams on the magnetic fields were examined using kinematic approximation and a variety of field configurations on the inner boundary. Kinematic and dynamic effects are discussed.

  9. The Effects of Fringe Fields on Organic Magnetoresistance

    NASA Astrophysics Data System (ADS)

    Harmon, Nicholas; Macià, Ferran; Wang, Fujian; Wohlgenannt, Markus; Kent, Andrew; Flatté, Michael

    2013-03-01

    The importance of random hyperfine fields is now widely acknowledged as a vital ingredient for the phenomena of organic magnetoresistance (OMAR). Recent experiments (Phys. Rev. X 2 021013 (2012)) have shown that another type of random field - fringe fields due to a nearby ferromagnet - can also dramatically affect magnetoconductivity. A theoretical analysis of the fringe field OMAR is challenging due to the different properties of the fringe fields when compared to the hyperfine fields. For instance, the range of fringe field strengths is 1-2 orders of magnitude larger than that of the hyperfine couplings. The correlation length between fringe fields is also larger by the same degree. We use a recent theory of OMAR that is well-suited to numerically calculate the magnetoresistance with both hyperfine and fringe fields present. We find agreement with key features of experimental fringe-field magnetoresistance dependences on applied magnetic field, including the field values of extrema of the magnetoresistance, the region of large magnetoresistance effects from the fringe fields, and the sign of the effect. This work was supported by an ARO MURI.

  10. Health Effects of Electromagnetic Fields: A Review of Literature.

    ERIC Educational Resources Information Center

    White, George L.; And Others

    1995-01-01

    Current evidence suggests that the effects of electromagnetic fields (EMF) disturb cell homeostasis at very low intensities by influencing discrete intracellular magnetic fields. The article reviews current research about the health effects of EMF, examining historical implications, childhood studies, adult studies, and popular press reports, and…

  11. The effects on the atmosphere of a major nuclear exchange

    SciTech Connect

    Not Available

    1985-01-01

    Most of the earth's population would survive the immediate horrors of a nuclear holocaust, but what long-term climatological changes would affect their ability to secure food and shelter. This sobering report considers the effects of fine dust from ground-level detonations, of smoke from widespread fires, and of chemicals released into the atmosphere. The authors use mathematical models of atmospheric processes and data from natural situations - e.g., volcanic eruptions and arctic haze - to draw their conclusions.

  12. Effective specific impulse of external nuclear pulse propulsion systems

    NASA Technical Reports Server (NTRS)

    Reynolds, T. W.

    1972-01-01

    An investigation of a simple self-similar flow model for an external nuclear pulse propulsion system indicates that to achieve the high effective specific impulse of such a system three principal factors are required. The are (1) attaining pulses of optimum energy, (2) attaining good propellant collimation, and (3) using an ablative material for the pusher surface which has high absorptivity for radiant energy at the propellant stagnation temperature.

  13. Disordered Nuclear Pasta, Magnetic Field Decay, and Crust Cooling in Neutron Stars

    NASA Astrophysics Data System (ADS)

    Horowitz, C. J.; Berry, D. K.; Briggs, C. M.; Caplan, M. E.; Cumming, A.; Schneider, A. S.

    2015-01-01

    Nuclear pasta, with nonspherical shapes, is expected near the base of the crust in neutron stars. Large-scale molecular dynamics simulations of pasta show long lived topological defects that could increase electron scattering and reduce both the thermal and electrical conductivities. We model a possible low-conductivity pasta layer by increasing an impurity parameter Qimp . Predictions of light curves for the low-mass x-ray binary MXB 1659-29, assuming a large Qimp, find continued late time cooling that is consistent with Chandra observations. The electrical and thermal conductivities are likely related. Therefore, observations of late time crust cooling can provide insight on the electrical conductivity and the possible decay of neutron star magnetic fields (assuming these are supported by currents in the crust).

  14. Disordered nuclear pasta, magnetic field decay, and crust cooling in neutron stars

    NASA Astrophysics Data System (ADS)

    Horowitz, C. J.; Berry, D. K.; Briggs, C. M.; Caplan, M. E.; Cumming, A.; Schneider, A. S.

    2015-04-01

    Nuclear pasta, with non-spherical shapes, is expected near the base of the crust in neutron stars. Large scale molecular dynamics simulations of pasta show long lived topological defects that could increase electron scattering and reduce both the thermal and electrical conductivities. We model a possible low conductivity pasta layer by increasing an impurity parameter Qimp. Predictions of light curves for the low mass X-ray binary MXB 1659-29, assuming a large Qimp, find continued late time cooling that is consistent with Chandra observations. The electrical and thermal conductivities are likely related. Therefore observations of late time crust cooling can provide insight on the electrical conductivity and the possible decay of neutron star magnetic fields (assuming these are supported by currents in the crust). This research was supported in part by DOE Grants DE-FG02-87ER40365 (Indiana University) and DE-SC0008808 (NUCLEI SciDAC Collaboration).

  15. A A field test for extremity dose assessment during outages at Korean nuclear power plants.

    PubMed

    Kim, Hee Geun; Kong, Tae Young

    2013-05-01

    During maintenance on the water chamber of a steam generator, the pressuriser heater and the pressure tube feeder in nuclear power plants, workers are likely to receive high radiation doses due to the severe workplace conditions. In particular, it is expected that workers' hands would receive the highest radiation doses because of their contact with the radioactive materials. In this study, field tests for extremity dose assessments in radiation workers undertaking contact tasks with high radiation doses were conducted during outages at pressurised water reactors and pressurised heavy water reactors in Korea. In the test, the radiation workers were required to wear additional thermoluminescent dosemeters (TLDs) on their backs and wrists and an extremity dosemeter on the finger, as well as a main TLD on the chest while performing the maintenance tasks. PMID:23091221

  16. Features of influence of dc magnetic field pulses on a nuclear spin echo in magnets

    NASA Astrophysics Data System (ADS)

    Mamniashvili, G. I.; Gegechkori, T. O.; Akhalkatsi, A. M.; Gavasheli, C. A.

    2012-06-01

    Signal intensities of a two-pulse nuclear spin echo as a function of parameters of dc magnetic field pulses are measured in the series of materials: Li0.5Fe2.5-xZnxO4 (x < 0.25) (enriched in 57Fe isotope to 96.8%), NiMnSb, Co2MnSi, La1-хСахMnO3 (x = 0.2; 0.25) and polycrystalline Co. Two types of dependences of these signals on a supplying time of such pulses with respect to the times of the exciting RF pulses are found. The mechanisms of influence of a domain structure and a dynamic frequency shift on the observed features of the investigated signals are discussed.

  17. Electroweak Sudakov Corrections using Effective Field Theory

    SciTech Connect

    Chiu Juiyu; Golf, Frank; Kelley, Randall; Manohar, Aneesh V.

    2008-01-18

    Electroweak Sudakov corrections of the form {alpha}{sup n}log{sup m}s/M{sub W,Z}{sup 2} are summed using renormalization group evolution in soft-collinear effective theory. Results are given for the scalar, vector, and tensor form factors for fermion and scalar particles. The formalism for including massive gauge bosons in soft-collinear effective theory is developed.

  18. Tunnel and field effect carrier ballistics

    NASA Technical Reports Server (NTRS)

    Kaiser, William J. (Inventor); Bell, L. Douglas (Inventor)

    1989-01-01

    Methods and apparatus for interacting carriers with a structure of matter employ an electrode for emitting said carriers at a distance from a surface of that structure, and cause such carriers to travel along ballistic trajectories inside that structure by providing along the mentioned distance a gap for performance of a process selected from the group of carrier tunneling and field emission and injecting carriers emitted by the mentioned electrode and that process ballistically into the structure through the gap and the mentioned surface. The carriers are collected or analyzed after their travel along ballistic trajectories in the structure of matter. Pertinent information on the inside of the structure is obtained by conducting inside that structure what conventionally would have been considered external ballistics, while performing the carrier-propelling internal ballistics conversely outside that structure.

  19. Influence of oblique magnetic field on electron cross-field transport in a Hall effect thruster

    SciTech Connect

    Miedzik, Jan; Daniłko, Dariusz; Barral, Serge

    2015-04-15

    The effects of the inclination of the magnetic field with respect to the channel walls in a Hall effect thruster are numerically studied with the use of a one-dimensional quasi-neutral Particle-In-Cell model with guiding center approximation of electron motion along magnetic lines. Parametric studies suggest that the incidence angle strongly influences electron transport across the magnetic field. In ion-focusing magnetic topologies, electrons collide predominantly on the side of the magnetic flux tube closer to the anode, thus increasing the electron cross-field drift. The opposite effect is observed in ion-defocussing topology.

  20. Influence of oblique magnetic field on electron cross-field transport in a Hall effect thruster

    NASA Astrophysics Data System (ADS)

    Miedzik, Jan; Barral, Serge; Daniłko, Dariusz

    2015-04-01

    The effects of the inclination of the magnetic field with respect to the channel walls in a Hall effect thruster are numerically studied with the use of a one-dimensional quasi-neutral Particle-In-Cell model with guiding center approximation of electron motion along magnetic lines. Parametric studies suggest that the incidence angle strongly influences electron transport across the magnetic field. In ion-focusing magnetic topologies, electrons collide predominantly on the side of the magnetic flux tube closer to the anode, thus increasing the electron cross-field drift. The opposite effect is observed in ion-defocussing topology.

  1. Microbes safely, effectively bioremediate oil field pits

    SciTech Connect

    Shaw, B. ); Block, C.S. ); Mills, C.H. )

    1995-01-30

    Natural and augmented bioremediation provides a safe, environmental, fast, and effective solution for removing hydrocarbon stains from soil. In 1992, Amoco sponsored a study with six bioremediation companies, which evaluated 14 different techniques. From this study, Amoco continued using Environmental Protection Co.'s (EPC) microbes for bioremediating more than 145 sites near Farmington, NM. EPC's microbes proved effective on various types of hydrocarbon molecules found in petroleum stained soils from heavy crude and paraffin to volatiles such as BTEX (benzene, toluene, ethylbenzene, xylene) compounds. Controlled laboratory tests have shown that these microbes can digest the hydrocarbon molecules with or without free oxygen present. It is believed that this adaptation gives these microbes their resilience. The paper describes the bioremediation process, environmental advantages, in situ and ex situ bioremediation, goals of bioremediation, temperature effects, time, cost, and example sites that were treated.

  2. 10 CFR 50.65 - Requirements for monitoring the effectiveness of maintenance at nuclear power plants.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... maintenance at nuclear power plants. 50.65 Section 50.65 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... Construction Permits § 50.65 Requirements for monitoring the effectiveness of maintenance at nuclear power..., including normal shutdown operations. (a)(1) Each holder of an operating license for a nuclear power...

  3. 10 CFR 50.65 - Requirements for monitoring the effectiveness of maintenance at nuclear power plants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... maintenance at nuclear power plants. 50.65 Section 50.65 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... Construction Permits § 50.65 Requirements for monitoring the effectiveness of maintenance at nuclear power..., including normal shutdown operations. (a)(1) Each holder of an operating license for a nuclear power...

  4. 10 CFR 50.65 - Requirements for monitoring the effectiveness of maintenance at nuclear power plants.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... maintenance at nuclear power plants. 50.65 Section 50.65 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... Construction Permits § 50.65 Requirements for monitoring the effectiveness of maintenance at nuclear power..., including normal shutdown operations. (a)(1) Each holder of an operating license for a nuclear power...

  5. 10 CFR 50.65 - Requirements for monitoring the effectiveness of maintenance at nuclear power plants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... maintenance at nuclear power plants. 50.65 Section 50.65 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC... Construction Permits § 50.65 Requirements for monitoring the effectiveness of maintenance at nuclear power..., including normal shutdown operations. (a)(1) Each holder of an operating license for a nuclear power...

  6. Effective kaon masses in dense nuclear and neutron matter

    NASA Astrophysics Data System (ADS)

    Waas, T.; Kaiser, N.; Weise, W.

    1996-02-01

    The effective mass and decay width of kaonic modes in baryonic matter are studied within a coupled-channel approach based on the Chiral SU(3) Effective Lagrangian which describes all available low energy data of the coupled overlineKN, π∑, πΛ system. Including Pauli blocking and Fermi motion in the kaon dispersion relation, we find a strong non-linear density dependence of the K - effective mass and decay width in symmetric nuclear matter at densities around 0.1 times normal nuclear matter density ϱ0 due to the in-medium dynamics of the Λ(1405) resonance. At higher densities the K - effective mass decreases slowly but stays above 0.5 mK at least up to densities below 3 ϱ0. In neutron matter the K - effective mass decreases almost linearly with increasing density but remains relatively large ( m K∗ > 0.65 m K) for ϱn ≲ 3 ϱ0. The K + effective mass turns out to increase very slowly with rising density.

  7. Effect of magnetic field inhomogeneity on ion cyclotron motion coherence at high magnetic field.

    PubMed

    Vladimirov, Gleb; Kostyukevich, Yury; Hendrickson, Christopher L; Blakney, Greg T; Nikolaev, Eugene

    2015-01-01

    A three-dimensional code based on the particle-in-cell algorithm modified to account for the inhomogeneity of the magnetic field was applied to determine the effect of Z(1), Z(2), Z(3), Z(4), X, Y, ZX, ZY, XZ(2) YZ(2), XY and X(2)-Y(2) components of an orthogonal magnetic field expansion on ion motion during detection in an FT-ICR cell. Simulations were performed for magnetic field strengths of 4.7, 7, 14.5 and 21 Tesla, including experimentally determined magnetic field spatial distributions for existing 4.7 T and 14.5 T magnets. The effect of magnetic field inhomogeneity on ion cloud stabilization ("ion condensation") at high numbers of ions was investigated by direct simulations of individual ion trajectories. Z(1), Z(2), Z(3) and Z(4) components have the largest effect (especially Z(1)) on ion cloud stability. Higher magnetic field strength and lower m/z demand higher relative magnetic field homogeneity to maintain cloud coherence for a fixed time period. The dependence of mass resolving power upper limit on Z(1) inhomogeneity is evaluated for different magnetic fields and m/z. The results serve to set the homogeneity requirements for various orthogonal magnetic field components (shims) for future FT-ICR magnet design. PMID:26307725

  8. Soft theorems from effective field theory

    NASA Astrophysics Data System (ADS)

    Larkoski, Andrew J.; Neill, Duff; Stewart, Iain W.

    2015-06-01

    The singular limits of massless gauge theory amplitudes are described by an effective theory, called soft-collinear effective theory (SCET), which has been applied most successfully to make all-orders predictions for observables in collider physics and weak decays. At tree-level, the emission of a soft gauge boson at subleading order in its energy is given by the Low-Burnett-Kroll theorem, with the angular momentum operator acting on a lower-point amplitude. For well separated particles at tree-level, we prove the Low-Burnett-Kroll theorem using matrix elements of subleading SCET Lagrangian and operator insertions which are individually gauge invariant. These contributions are uniquely determined by gauge invariance and the reparametrization invariance (RPI) symmetry of SCET. RPI in SCET is connected to the infinite-dimensional asymptotic symmetries of the S-matrix. The Low-Burnett-Kroll theorem is generically spoiled by on-shell corrections, including collinear loops and collinear emissions. We demonstrate this explicitly both at tree-level and at one-loop. The effective theory correctly describes these configurations, and we generalize the Low-Burnett-Kroll theorem into a new one-loop subleading soft theorem for amplitudes. Our analysis is presented in a manner that illustrates the wider utility of using effective theory techniques to understand the perturbative S-matrix.

  9. Magnetic field evolution in white dwarfs: The hall effect and complexity of the field

    NASA Technical Reports Server (NTRS)

    Muslimov, A. G.; Van Horn, H. M.; Wood, M. A.

    1995-01-01

    We calculate the evolution of the magnetic fields in white dwarfs, taking into account the Hall effect. Because this effect depends nonlinearly upon the magnetic field strength B, the time dependences of the various multipole field components are coupled. The evolution of the field is thus significantly more complicated than has been indicated by previous investigations. Our calculations employ recent white dwarf evolutionary sequences computed for stars with masses 0.4, 0.6, 0.8, and 1.0 solar mass. We show that in the presence of a strong (up to approximately 10(exp 9) G) internal toroidal magnetic field; the evolution of even the lowest order poloidal modes can be substantially changed by the Hall effect. As an example, we compute the evolution of an initially weak quadrupole component, which we take arbitrarily to be approximately 0.1%-1% of the strength of a dominant dipole field. We find that coupling provided by the Hall effect can produce growth of the ratio of the quadrupole to the dipole component of the surface value of the magnetic field strength by more than a factor of 10 over the 10(exp 9) to 10(exp 10) year cooling lifetime of the white dwarf. Some consequences of these results for the process of magnetic-field evolution in white dwarfs are briefly discussed.

  10. p -shell carrier assisted dynamic nuclear spin polarization in single quantum dots at zero external magnetic field

    NASA Astrophysics Data System (ADS)

    Fong, C. F.; Ota, Y.; Harbord, E.; Iwamoto, S.; Arakawa, Y.

    2016-03-01

    Repeated injection of spin-polarized carriers in a quantum dot (QD) leads to the polarization of nuclear spins, a process known as dynamic nuclear spin polarization (DNP). Here, we report the observation of p-shell carrier assisted DNP in single QDs at zero external magnetic field. The nuclear field—measured by using the Overhauser shift of the singly charged exciton state of the QDs—continues to increase, even after the carrier population in the s-shell saturates. This is also accompanied by an abrupt increase in nuclear spin buildup time as p-shell emission overtakes that of the s shell. We attribute the observation to p-shell electrons strongly altering the nuclear spin dynamics in the QD, supported by numerical simulation results based on a rate equation model of coupling between electron and nuclear spin system. Dynamic nuclear spin polarization with p-shell carriers could open up avenues for further control to increase the degree of nuclear spin polarization in QDs.

  11. Modeling of radiation effects on nuclear waste package materials

    SciTech Connect

    Simonson, S.A.

    1988-09-01

    A methodology is developed for the assessment of radiation effects on nuclear waste package materials. An assessment of the current status of understanding with regard to waste package materials and their behavior in radiation environments is presented. The methodology is used to make prediction as to the chemically induced changes in the groundwater surrounding nuclear waste packages in a repository in tuff. The predictions indicate that mechanisms not currently being pursued by the Department of Energy may be a factor in the long-term performance of nuclear waste packages. The methodology embodies a physical model of the effects of radiation on aqueous solutions. Coupled to the physical model is a method for analyzing the complex nature of the physical model using adjoint sensitivity analysis. The sensitivity aid in both the physical understanding of the processes involved as well as aiding in eliminating portions of the model that have no bearing on the desired results. A computer implementation of the methodology is provided. 128 refs.

  12. Characterization of Radiation Fields in Biological Shields of Nuclear Power Plants for Assessing Concrete Degradation

    NASA Astrophysics Data System (ADS)

    Remec, Igor; Rosseel, Thomas M.; Field, Kevin G.; Le Pape, Yann

    2016-02-01

    Life extensions of nuclear power plants to 60 and potentially 80 years of operation have renewed interest in long-term material degradation. One material being considered is concrete, with a particular focus on radiation-induced effects. Based on the projected neutron fluence values (E > 0.1 MeV) in the concrete biological shields of the US pressurized water reactor fleet and the available data on radiation effects on concrete, some decrease in mechanical properties of concrete cannot be ruled out during extended operation beyond 60 years. An expansion of the irradiated concrete database and a reliable determination of relevant neutron fluence energy cutoff value are necessary to ensure reliable risk assessment for extended operation of nuclear power plants. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC0500OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

  13. SQUIDs vs. Faraday coils for ultlra-low field nuclear magnetic resonance: experimental and simulation comparison

    SciTech Connect

    Matlashov, Andrei N; Espy, Michelle A; Kraus, Robert H; Sayukov, Igor M; Schultz, Larry J; Urbaitis, Algis V; Volegov, Petr L; Wurden, Caroline J

    2010-01-01

    Nuclear magnetic resonance (NMR) methods are widely used in medicine, chemistry and industry. One application area is magnetic resonance imaging or MRI. Recently it has become possible to perform NMR and MRI in ultra-low field (ULF) regime that requires measurement field strengths only of the order of 1 Gauss. These techniques exploit the advantages offered by superconducting quantum interference devices or SQUIDs. Our group at LANL has built SQUID based MRI systems for brain imaging and for liquid explosives detection at airports security checkpoints. The requirement for liquid helium cooling limits potential applications of ULF MRI for liquid identification and security purposes. Our experimental comparative investigation shows that room temperature inductive magnetometers provide enough sensitivity in the 3-10 kHz range and can be used for fast liquid explosives detection based on ULF NMR/MRI technique. We describe an experimental and computer simulation comparison of the world's first multichannel SQUID based and Faraday coils based instruments that are capable of performing ULF MRI for liquids identification.

  14. Determining diffusion coefficients of ionic liquids by means of field cycling nuclear magnetic resonance relaxometry.

    PubMed

    Kruk, D; Meier, R; Rachocki, A; Korpała, A; Singh, R K; Rössler, E A

    2014-06-28

    Field Cycling Nuclear Magnetic Resonance (FC NMR) relaxation studies are reported for three ionic liquids: 1-ethyl-3- methylimidazolium thiocyanate (EMIM-SCN, 220-258 K), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4, 243-318 K), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6, 258-323 K). The dispersion of (1)H spin-lattice relaxation rate R1(ω) is measured in the frequency range of 10 kHz-20 MHz, and the studies are complemented by (19)F spin-lattice relaxation measurements on BMIM-PF6 in the corresponding frequency range. From the (1)H relaxation results self-diffusion coefficients for the cation in EMIM-SCN, BMIM-BF4, and BMIM-PF6 are determined. This is done by performing an analysis considering all relevant intra- and intermolecular relaxation contributions to the (1)H spin-lattice relaxation as well as by benefiting from the universal low-frequency dispersion law characteristic of Fickian diffusion which yields, at low frequencies, a linear dependence of R1 on square root of frequency. From the (19)F relaxation both anion and cation diffusion coefficients are determined for BMIM-PF6. The diffusion coefficients obtained from FC NMR relaxometry are in good agreement with results reported from pulsed- field-gradient NMR. This shows that NMR relaxometry can be considered as an alternative route of determining diffusion coefficients of both cations and anions in ionic liquids. PMID:24985656

  15. Determining diffusion coefficients of ionic liquids by means of field cycling nuclear magnetic resonance relaxometry

    NASA Astrophysics Data System (ADS)

    Kruk, D.; Meier, R.; Rachocki, A.; Korpała, A.; Singh, R. K.; Rössler, E. A.

    2014-06-01

    Field Cycling Nuclear Magnetic Resonance (FC NMR) relaxation studies are reported for three ionic liquids: 1-ethyl-3- methylimidazolium thiocyanate (EMIM-SCN, 220-258 K), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4, 243-318 K), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6, 258-323 K). The dispersion of 1H spin-lattice relaxation rate R1(ω) is measured in the frequency range of 10 kHz-20 MHz, and the studies are complemented by 19F spin-lattice relaxation measurements on BMIM-PF6 in the corresponding frequency range. From the 1H relaxation results self-diffusion coefficients for the cation in EMIM-SCN, BMIM-BF4, and BMIM-PF6 are determined. This is done by performing an analysis considering all relevant intra- and intermolecular relaxation contributions to the 1H spin-lattice relaxation as well as by benefiting from the universal low-frequency dispersion law characteristic of Fickian diffusion which yields, at low frequencies, a linear dependence of R1 on square root of frequency. From the 19F relaxation both anion and cation diffusion coefficients are determined for BMIM-PF6. The diffusion coefficients obtained from FC NMR relaxometry are in good agreement with results reported from pulsed- field-gradient NMR. This shows that NMR relaxometry can be considered as an alternative route of determining diffusion coefficients of both cations and anions in ionic liquids.

  16. ARC: A compact, high-field, disassemblable fusion nuclear science facility and demonstration power plant

    NASA Astrophysics Data System (ADS)

    Sorbom, Brandon; Ball, Justin; Palmer, Timothy; Mangiarotti, Franco; Sierchio, Jennifer; Bonoli, Paul; Kasten, Cale; Sutherland, Derek; Barnard, Harold; Haakonsen, Christian; Goh, Jon; Sung, Choongki; Whyte, Dennis

    2014-10-01

    The Affordable, Robust, Compact (ARC) reactor conceptual design aims to reduce the size, cost, and complexity of a combined Fusion Nuclear Science Facility (FNSF) and demonstration fusion pilot power plant. ARC is a 270 MWe tokamak reactor with a major radius of 3.3 m, a minor radius of 1.1 m, and an on-axis magnetic field of 9.2 T. ARC has Rare Earth Barium Copper Oxide (REBCO) superconducting toroidal field coils with joints to allow disassembly, allowing for removal and replacement of the vacuum vessel as a single component. Inboard-launched current drive of 25 MW LHRF power and 13.6 MW ICRF power is used to provide a robust, steady state core plasma far from disruptive limits. ARC uses an all-liquid blanket, consisting of low pressure, slowly flowing Fluorine Lithium Beryllium (FLiBe) molten salt. The liquid blanket acts as a working fluid, coolant, and tritium breeder, and minimizes the solid material that can become activated. The large temperature range over which FLiBe is liquid permits blanket operation at 800-900 K with single phase fluid cooling and allows use of a high-efficiency Brayton cycle for electricity production in the secondary coolant loop.

  17. Comparative study of nuclear masses in the relativistic mean-field model

    NASA Astrophysics Data System (ADS)

    Hua, XueMin; Heng, TaiHua; Niu, ZhongMing; Sun, BaoHua; Guo, JianYou

    2012-12-01

    With experimental masses updated from AME11, the predictive power of relativistic mean-field (RMF) mass model is carefully examined and compared with HFB-17, FRDM, WS*, and DZ28 mass models. In the relativistic mean-field model, the calculation with the PC-PK1 has improved significantly in describing masses compared to the TMA, especially for the neutron-deficient nuclei. The corresponding rms deviation with respect to the known masses falls to 1.4 MeV. Furthermore, it is found that the RMF mass model better describes the nuclei with large deformations. The rms deviation for nuclei with the absolute value of quadrupole deformation parameter greater than 0.25 falls to 0.93, crossing the 1 MeV accuracy threshold for the PC-PK1, which may indicate the new model is more suitable for those largely-deformed nuclei. In addition, the necessity of new high-precision experimental data to evaluate and develop the nuclear mass models is emphasized as well.

  18. SQUIDs vs. Induction Coils for Ultra-Low Field Nuclear Magnetic Resonance: Experimental and Simulation Comparison.

    PubMed

    Matlashov, Andrei N; Schultz, Larry J; Espy, Michelle A; Kraus, Robert H; Savukov, Igor M; Volegov, Petr L; Wurden, Caroline J

    2011-01-01

    Nuclear magnetic resonance (NMR) is widely used in medicine, chemistry and industry. One application area is magnetic resonance imaging (MRI). Recently it has become possible to perform NMR and MRI in the ultra-low field (ULF) regime requiring measurement field strengths of the order of only 1 Gauss. This technique exploits the advantages offered by superconducting quantum interference devices or SQUIDs. Our group has built SQUID based MRI systems for brain imaging and for liquid explosives detection at airport security checkpoints. The requirement for liquid helium cooling limits potential applications of ULF MRI for liquid identification and security purposes. Our experimental comparative investigation shows that room temperature inductive magnetometers may provide enough sensitivity in the 3-10 kHz range and can be used for fast liquid explosives detection based on ULF NMR technique. We describe experimental and computer-simulation results comparing multichannel SQUID based and induction coils based instruments that are capable of performing ULF MRI for liquid identification. PMID:21747638

  19. Nuclear matter from effective quark-quark interaction.

    PubMed

    Baldo, M; Fukukawa, K

    2014-12-12

    We study neutron matter and symmetric nuclear matter with the quark-meson model for the two-nucleon interaction. The Bethe-Bruckner-Goldstone many-body theory is used to describe the correlations up to the three hole-line approximation with no extra parameters. At variance with other nonrelativistic realistic interactions, the three hole-line contribution turns out to be non-negligible and to have a substantial saturation effect. The saturation point of nuclear matter, the compressibility, the symmetry energy, and its slope are within the phenomenological constraints. Since the interaction also reproduces fairly well the properties of the three-nucleon system, these results indicate that the explicit introduction of the quark degrees of freedom within the considered constituent quark model is expected to reduce the role of three-body forces. PMID:25541769

  20. Psychological Effects of the Threat of Nuclear War

    PubMed Central

    Kiraly, S. J.

    1986-01-01

    Systematic studies are emerging on the prevailing harmful psychological effect of the threat of nuclear war. The most recent surveys have identified populations which are particularly vulnerable. Anxiety was found to be a factor in criminal behavior, and threat of nuclear war to be a factor in anxiety. Psychiatric morbidity has been correlated with work deprivation and threat of annihilation. Many studies have focused on children, finding that anxiety about social issues is high, but that cynicism and apathy set in rapidly. Conclusions from such studies show that denial and avoidance are some of the worst results, since they are a barrier to meaningful reaction. The most vulnerable groups are children, adolescents, the unemployed, and those responsible for the welfare of others. Appropriate action is seen to be acknowledgement of fear and disillusionment as valid feelings, education towards a stronger sense of reality, and mobilization of goal-directed activity. PMID:21274254

  1. Effect of nuclear ownership on utility bond ratings and yields

    SciTech Connect

    Nesse, R.J.

    1982-02-01

    The major objective of this study was to test the hypothesis that investors have required an additional interest rate premium before purchasing bonds of utilities with large investments in nuclear facilities. The study required several tasks. First, the literature relating to firm bankruptcy and default was reviewed. Second, the failing financial health of the electric utility industry was assessed in terms of construction problems, the impact of federal and state regulations, and the impact of Three Mile Island. Finally, data were collected on 63 electric utilities. This allowed statistical estimation of the magnitude of the risk premium associated with utility involvement in nuclear power. The effect of this involvement on a utility's bond ratings was also examined. Multiple regression was the statistical tool used for the statistical testing and estimation.

  2. Characterization of Radiation Fields in Biological Shields of Nuclear Power Plants for Assessing Concrete Degradation

    SciTech Connect

    Remec, Igor; Rosseel, Thomas M; Field, Kevin G; Pape, Yann Le

    2016-01-01

    Life extensions of nuclear power plants to 60 and potentially 80 years of operation have renewed interest in long-term material degradation. One material being considered is concrete with a particular focus on radiation-induced effects. Based on the projected neutron fluence (E > 0.1 MeV) values in the concrete biological shields of the US PWR fleet and the available data on radiation effects on concrete, some decrease in mechanical properties of concrete cannot be ruled out during extended operation beyond 60 years. An expansion of the irradiated concrete database and a reliable determination of relevant neutron fluence energy cutoff value are necessary to assure reliable risk assessment for NPPs extended operation.

  3. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: The importance of level crossings

    PubMed Central

    Thurber, Kent R.; Tycko, Robert

    2012-01-01

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T1e is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants. PMID:22938251

  4. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: the importance of level crossings.

    PubMed

    Thurber, Kent R; Tycko, Robert

    2012-08-28

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T(1e) is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants. PMID:22938251

  5. Quadrature Rotating-Frame Gradient Fields for Ultra-Low FieldNuclear Magnetic Resonance and Imaging

    SciTech Connect

    Bouchard, Louis-Serge

    2005-12-30

    Magnetic resonance imaging (MRI) in very low fields isfundamentally limited by untruncated concomitant gradients which causesevere distortions in image acquisition and volume selection if thegradient fields are strong compared to the static field. In this paper,it is shown that gradient fields oscillating in quadrature can be usedfor spatial encoding in low fields and provide substantial improvementsover conventional encoding methods using static gradients. In particular,cases where the gradient field is comparable to or higher than theexternal field, Gmax/B0>1, are examined. It is shown thatundistorted slice selection and image encoding is possible because ofsmaller geometric phase errors introduced during cyclic motions of theHamiltonian. In the low field limit (Gmax/B_0 ->infinity) sliceselection is achieved with a combination of soft pulse segments and acoherent train of hard pulses to average out concomitant fields over thefast scale of the rf Hamiltonian.

  6. Biological effects of electromagnetic fields and recently updated safety guidelines for strong static magnetic fields.

    PubMed

    Yamaguchi-Sekino, Sachiko; Sekino, Masaki; Ueno, Shoogo

    2011-01-01

    Humans are exposed daily to artificial and naturally occurring magnetic fields that originate from many different sources. We review recent studies that examine the biological effects of and medical applications involving electromagnetic fields, review the properties of static and pulsed electromagnetic fields that affect biological systems, describe the use of a pulsed electromagnetic field in combination with an anticancer agent as an example of a medical application that incorporates an electromagnetic field, and discuss the recently updated safety guidelines for static electromagnetic fields. The most notable modifications to the 2009 International Commission on Non-Ionizing Radiation Protection guidelines are the increased exposure limits, especially for those who work with or near electromagnetic fields (occupational exposure limits). The recommended increases in exposure were determined using recent scientific evidence obtained from animal and human studies. Several studies since the 1994 publication of the guidelines have examined the effects on humans after exposure to high static electromagnetic fields (up to 9.4 tesla), but additional research is needed to ascertain further the safety of strong electromagnetic fields. PMID:21441722

  7. High-Accuracy Calculation of cu Electric-Field Gradients: a Revision of the cu Nuclear Quadrupole Moment Value

    NASA Astrophysics Data System (ADS)

    Cheng, Lan; Matthews, Devin A.; Gauss, Jürgen; Stanton, John F.

    2015-06-01

    A revision of the value for the Cu nuclear quadrupole moment (NQM) is reported based on high-accuracy ab initio calculations on the Cu electric field gradients in the CuF and CuCl molecules. Electron-correlation effects have systematically been taken into account using a hierarchy of coupled-cluster methods including up to quadruple excitations. It is shown that the CCSD(T)_Λ method provides a more reliable treatment of triples corrections for Cu electric-field gradients than the ubiquitously applied CCSD(T) method, which is tentatively attributed to the importance of the wavefunction relaxation in the calculations of a core property. Augmenting large-basis-set CCSD(T)_Λ results with the remaining corrections obtained using additive schemes, including full triples contributions, quadruples contributions, zero-point vibrational corrections, spin-orbit corrections, as well as the correction from the Gaunt term, a new value of 209.7(50) mbarn for the Cu NQM has been obtained. The new value substantially reduces the uncertainty of this parameter in comparison to the standard value of 220(15) mbarn obtained from a previous muonic experiment.

  8. Double binding energy differences: Mean-field or pairing effect?

    NASA Astrophysics Data System (ADS)

    Qi, Chong

    2012-10-01

    In this Letter we present a systematic analysis on the average interaction between the last protons and neutrons in atomic nuclei, which can be extracted from the double differences of nuclear binding energies. The empirical average proton-neutron interaction Vpn thus derived from experimental data can be described in a very simple form as the interplay of the nuclear mean field and the pairing interaction. It is found that the smooth behavior as well as the local fluctuations of the Vpn in even-even nuclei with N ≠ Z are dominated by the contribution from the proton-neutron monopole interactions. A strong additional contribution from the isoscalar monopole interaction and isovector proton-neutron pairing interaction is seen in the Vpn for even-even N = Z nuclei and for the adjacent odd-A nuclei with one neutron or proton being subtracted.

  9. Graphene-based field effect transistors for radiation-induced field sensing

    NASA Astrophysics Data System (ADS)

    Di Gaspare, Alessandra; Valletta, Antonio; Fortunato, Guglielmo; Larciprete, Rosanna; Mariucci, Luigi; Notargiacomo, Andrea; Cimino, Roberto

    2016-07-01

    We propose the implementation of graphene-based field effect transistor (FET) as radiation sensor. In the proposed detector, graphene obtained via chemical vapor deposition is integrated into a Si-based field effect device as the gate readout electrode, able to sense any change in the field distribution induced by ionization in the underneath absorber, because of the strong variation in the graphene conductivity close to the charge neutrality point. Different 2-dimensional layered materials can be envisaged in this kind of device.

  10. Environmental and health effects of the nuclear industry and nuclear weapons: a current evaluation.

    PubMed

    Johnson, C J

    1982-01-01

    The nuclear weapons industry in the U.S. comprises nine major plants, supported by a network of subcontractors and grantee institutions. Weapons development progresses at the Lawrence Livermore and Los Alamos Laboratories under the auspices of the University of California. Fissionable materials and tritium are produced at the Savannah River Plant (du Pont) or at Hanford. Reprocessing of plutonium and weapons grade uranium and manufacture of components are carried out at Rocky Flats (formerly Dow, now Rockwell Int.). Large amounts of radionuclides are generated or involved in operations at most of the nine plants. Internal reports of surveillance efforts by weapons plant personnel to monitor emissions of radioactive gases and particulates have now been released by several of the plants (in one case through litigation). Those reports document major releases of radioactive gases and particulates to the environment in the past, and continuing routine releases of some importance. Few investigations have been made of effects from these potent carcinogens in local populations. There have been several preliminary reports (Rocky Flats, Los Alamos and Savannah River) and one comprehensive report [Ambio 10: 176 (1981)]. Evidence of significantly increased rates of cancer of the more radiosensitive organs has been demonstrated. Adequate cancer registry and vital statistics data are essential for the comprehensive investigations of somatic and genetic effects which should be carried out around all nuclear installations near population centres. PMID:6765303

  11. Some Nuclear Techniques in Experimental Magnetism: Mössbauer Effect, Neutron Scattering and Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Piecuch, Michel

    The goal of this chapter is to present three traditional methods for the study of magnetic properties : Mössbauer effect, neutron diffraction and nuclear magnetic resonance. It begins by recalling the basic properties of atomic nuclei and describing the hyperfine interactions between the nucleus and its surrounding. Then, the recoilless absorption of γ-rays by crystal, the Mössbauer effect is presented, we discuss the main parameters measured and show one example of application. Next we present neutron interactions with matter, the interaction of neutrons with the atomic nucleus and the interaction of the neutron magnetic moment with the magnetic moment of electrons. The use of polarized neutron and the inelastic scattering of neutrons are also discussed. The comparison between neutron experiments and synchrotron radiation techniques is briefly reviewed. One example of the use of neutron scattering in the domain of thin film magnetism is shown. Finally, we present the basic theory of nuclear magnetic resonance and one application of this technique to the study of Co/Cu multilayers.

  12. Diamond nitrogen vacancy electronic and nuclear spin-state anti-crossings under weak transverse magnetic fields

    NASA Astrophysics Data System (ADS)

    Clevenson, Hannah; Chen, Edward; Dolde, Florian; Teale, Carson; Englund, Dirk; Braje, Danielle

    2016-05-01

    We report on detailed studies of electronic and nuclear spin states in the diamond nitrogen vacancy (NV) center under moderate transverse magnetic fields. We numerically predict and experimentally verify a previously unobserved NV ground state hyperfine anti-crossing occurring at magnetic bias fields as low as tens of Gauss - two orders of magnitude lower than previously reported hyperfine anti-crossings at ~ 510 G and ~ 1000 G axial magnetic fields. We then discuss how this regime can be optimized for magnetometry and other sensing applications and propose a method for how the nitrogen-vacancy ground state Hamiltonian can be manipulated by small transverse magnetic fields to polarize the nuclear spin state. Acknowlegement: The Lincoln Laboratory portion of this work is sponsored by the Assistant Secretary of Defense for Research & Engineering under Air Force Contract #FA8721-05-C-0002. Opinions, interpretations, conclusions and recommendations are those of the authors and are not necessarily endorsed by the United States Government.

  13. Radiation effects on organic materials in nuclear plants. Final report

    SciTech Connect

    Bruce, M B; Davis, M V

    1981-11-01

    A literature search was conducted to identify information useful in determining the lowest level at which radiation causes damage to nuclear plant equipment. Information was sought concerning synergistic effects of radiation and other environmental stresses. Organic polymers are often identified as the weak elements in equipment. Data on radiation effects are summarized for 50 generic name plastics and 16 elastomers. Coatings, lubricants, and adhesives are treated as separate groups. Inorganics and metallics are considered briefly. With a few noted exceptions, these are more radiation resistant than organic materials. Some semiconductor devices and electronic assemblies are extremely sensitive to radiation. Any damage threshold including these would be too low to be of practical value. With that exception, equipment exposed to less than 10/sup 4/ rads should not be significantly affected. Equipment containing no Teflon should not be significantly affected by 10/sup 5/ rads. Data concerning synergistic effects and radiation sensitization are discussed. The authors suggest correlations between the two effects.

  14. Effective field theory of broken spatial diffeomorphisms

    NASA Astrophysics Data System (ADS)

    Lin, Chunshan; Labun, Lance Z.

    2016-03-01

    We study the low energy effective theory describing gravity with broken spatial diffeomorphism invariance. In the unitary gauge, the Goldstone bosons associated with broken diffeomorphisms are eaten and the graviton becomes a massive spin-2 particle with 5 well-behaved degrees of freedom. In this gauge, the most general theory is built with the lowest dimension operators invariant under only temporal diffeomorphisms. Imposing the additional shift and SO(3) internal symmetries, we analyze the perturbations on a FRW background. At linear perturbation level, the observables of this theory are characterized by five parameters, including the usual cosmological parameters and one additional coupling constant for the symmetry-breaking scalars. In the de Sitter and Minkowski limit, the three Goldstone bosons are supermassive and can be integrated out, leaving two massive tensor modes as the only propagating degrees of freedom. We discuss several examples relevant to theories of massive gravity.

  15. Calculation of Radiofrequency Electromagnetic Fields and Their Effects in MRI of Human Subjects

    PubMed Central

    Collins, Christopher M.; Wang, Zhangwei

    2011-01-01

    Radiofrequency magnetic fields are critical to nuclear excitation and signal reception in Magnetic Resonance Imaging (MRI). The interactions between these fields and human tissues in anatomical geometries results in a variety of effects regarding image integrity and safety of the human subject. In recent decades numerical methods of calculation have been used increasingly to understand the effects of these interactions and aid in engineering better, faster, and safer equipment and methods. As MRI techniques and technology have evolved through the years, so too have the requirements for meaningful interpretation of calculation results. Here we review the basic physics of RF electromagnetics in MRI and discuss a variety of ways RF field calculations are used in MRI in engineering and safety assurance from simple systems and sequences through advanced methods of development for the future. PMID:21381106

  16. Summarizing lecture: factors influencing enzymatic H-transfers, analysis of nuclear tunnelling isotope effects and thermodynamic versus specific effects

    PubMed Central

    Marcus, R.A

    2006-01-01

    In the articles in this Discussion, a wide variety of topics are treated, including reorganization energy, initially introduced for electron transfers (‘environmentally assisted tunnelling’), nuclear tunnelling, H/D and C12/C13 kinetic isotope effects (KIEs), the effect of changes of distal and nearby amino acid residues using site-directed mutagenesis, and dynamics versus statistical effects. A coordinate-free form of semi-classical theory is used to examine topics on data such as tunnelling versus ‘over-the-barrier’ paths and temperature and pressure effects on KIEs. The multidimensional semi-classical theory includes classically allowed and classically forbidden transitions. More generally, we address the question of relating kinetic to thermodynamic factors, as in the electron transfer field, so learning about specific versus thermodynamic effects in enzyme catalysis and KIEs. PMID:16873131

  17. Effects of a scalar scaling field on quantum mechanics

    NASA Astrophysics Data System (ADS)

    Benioff, Paul

    2016-07-01

    This paper describes the effects of a complex scalar scaling field on quantum mechanics. The field origin is an extension of the gauge freedom for basis choice in gauge theories to the underlying scalar field. The extension is based on the idea that the value of a number at one space time point does not determine the value at another point. This, combined with the description of mathematical systems as structures of different types, results in the presence of separate number fields and vector spaces as structures, at different space time locations. Complex number structures and vector spaces at each location are scaled by a complex space time dependent scaling factor. The effect of this scaling factor on several physical and geometric quantities has been described in other work. Here the emphasis is on quantum mechanics of one and two particles, their states and properties. Multiparticle states are also briefly described. The effect shows as a complex, nonunitary, scalar field connection on a fiber bundle description of nonrelativistic quantum mechanics. The lack of physical evidence for the presence of this field so far means that the coupling constant of this field to fermions is very small. It also means that the gradient of the field must be very small in a local region of cosmological space and time. Outside this region, there are no restrictions on the field gradient.

  18. Effects of a scalar scaling field on quantum mechanics

    NASA Astrophysics Data System (ADS)

    Benioff, Paul

    2016-04-01

    This paper describes the effects of a complex scalar scaling field on quantum mechanics. The field origin is an extension of the gauge freedom for basis choice in gauge theories to the underlying scalar field. The extension is based on the idea that the value of a number at one space time point does not determine the value at another point. This, combined with the description of mathematical systems as structures of different types, results in the presence of separate number fields and vector spaces as structures, at different space time locations. Complex number structures and vector spaces at each location are scaled by a complex space time dependent scaling factor. The effect of this scaling factor on several physical and geometric quantities has been described in other work. Here the emphasis is on quantum mechanics of one and two particles, their states and properties. Multiparticle states are also briefly described. The effect shows as a complex, nonunitary, scalar field connection on a fiber bundle description of nonrelativistic quantum mechanics. The lack of physical evidence for the presence of this field so far means that the coupling constant of this field to fermions is very small. It also means that the gradient of the field must be very small in a local region of cosmological space and time. Outside this region, there are no restrictions on the field gradient.

  19. Solar modulation and nuclear fragmentation effects in galactic cosmic ray transport through shielding

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.; Cucinotta, C. F.; Wilson, J. W.; Shinn, J. L.; Badhwar, G.

    1994-01-01

    Crews of manned interplanetary missions may accumulate significant radiation exposures from the Galactic Cosmic Ray (GCR) environment in space. Estimates of how these dose levels are affected by the assumed temporal and spatial variations in the composition of the GCR environment, and by the effects of the spacecraft and body self-shielding on the transported fields are presented. In this work, the physical processes through which shielding alters the transported radiation fields are described. We then present estimates of the effects on model calculations of (1) nuclear fragmentation model uncertainties, (2) solar modulation, (3) variations between solar cycles, and (4) proposed changes to the quality factors which relate dose equivalent to absorbed dose.

  20. IMMUNOLOGIC EFFECTS OF ELECTROMAGNETIC FIELDS (1981-1983)

    EPA Science Inventory

    In vitro studies provide evidence that support and EM field induced thermal mechanism for immune effects. When proper control of culture temperatures has been achieved during in vitro exposure to EM fields, no alterations have been observed for a variety of immune cell functions....

  1. Effects of Radial Electric Fields on ICRF Waves

    SciTech Connect

    C.K. Phillips; J.C. Hosea; M. Ono; J.R. Wilson

    2001-06-18

    Equilibrium considerations infer that large localized radial electric fields are associated with internal transport barrier structures in tokamaks and other toroidal magnetic confinement configurations. In this paper, the effects of an equilibrium electric field on fast magnetosonic wave propagation are considered in the context of a cold plasma model.

  2. Utilizing Field-Based Instruction as an Effective Teaching Strategy

    ERIC Educational Resources Information Center

    Kozar, Joy M.; Marcketti, Sara B.

    2008-01-01

    The purpose of this study was to examine the effectiveness of field-based instruction on student learning outcomes. Researchers in the past have noted the importance of engaging students on a deeper level through the use of active course designs. To investigate the outcomes of active learning, two field assignments created for two separate…

  3. Approximate analytical solution for nuclear matter in a mean-field Walecka model and Coester line behavior

    SciTech Connect

    Delfino, A.; Silva, J.B.; Malheiro, M.

    2006-03-15

    We study nuclear matter, at the mean-field approximation, by considering as equal the values of the scalar and the vector density in the Walecka model, which is a very reasonable approximation up to the nuclear matter saturation density. It turns out that the model has an analytical solution for the scalar and vector couplings as functions only of the nuclear matter density and binding energy. The nuclear matter properties are very close to the original version of the model. This solution allows us to show that the correlation between the binding energy and the saturation density is Coester line like. The liquid-gas phase transition is also studied and the critical and flash temperatures are again very similar to the original ones.

  4. Spatial aspects of nuclear magnetic resonance spectroscopy: Static and radio-frequency magnetic field gradients in principle and practice

    NASA Astrophysics Data System (ADS)

    Sodickson, Aaron David

    All nuclear magnetic resonance (NMR) measurements are influenced by the spatial distribution of spin properties across the sample volume. This thesis presents a general theoretical treatment of spatial phenomena in NMR along with a number of experimental explorations. A generalized k space formalism is described which lends physical insight into the spatial modulations underlying a wide variety of NMR experiments. The approach involves a Fourier decomposition of spin coherences into a set of basis functions that most naturally describes the evolution of the system under field gradients and RF pulses. It provides a straightforward physical interpretation of the sample's spatial behavior while simplifying the calculation of analytical results for any signal pathway of interest. The formalism is applied to a diverse range of NMR experiments, including imaging, echo experiments, flow and diffusion measurements, selective excitation sequences, and multiple quantum coherence pathway selection techniques. A modification of the BIRD and TANGO sequences is presented which incorporates RF gradients to eliminate the net magnetization from uncoupled spins, while completely preserving magnetization with the proper scalar-coupling constant. The spatial variation of the B1 field strength-here due to the residual field inhomogeneity of a nominally homogeneous coil-causes dephasing of the uncoupled line while refocussing the desired magnetization in a rotary echo. The sequence is demonstrated for selective excitation of the satellites in a chloroform sample, yielding suppression of the uncoupled magnetization by a factor of approximately 800. A simplified approach to shimming for a high resolution magic angle spinning (MAS) probe is developed. Correction fields of the desired symmetry about the sample's spinning axis are derived as linear combinations of the usual lab-frame spherical harmonic shim-field geometries. The effects of sample spinning are incorporated which further

  5. Nuclear magnetic resonance-paramagnetic relaxation enhancements: Influence of spatial quantization of the electron spin when the zero-field splitting energy is larger than the Zeeman energy

    NASA Astrophysics Data System (ADS)

    Abernathy, S. M.; Miller, J. C.; Lohr, L. L.; Sharp, R. R.

    1998-09-01

    Dissolved paramagnetic ions generally provide an efficient mechanism for the relaxation of nuclear spins in solution, a phenomenon called the nuclear magnetic resonance-paramagnetic relaxation enhancement (NMR-PRE). Metal ions with electron spins S⩾1 exhibit rich NMR relaxation phenomena originating in the properties of the zero-field splitting (zfs) interaction, which vanishes for spin-1/2 ions but which is nonzero for S⩾1 ions in site symmetry lower than cubic. For S⩾1 ions in the vicinity of the zfs-limit, i.e., at magnetic-field strengths low enough that the zfs energy exceeds the Zeeman energy, the NMR-PRE depends strongly on the detailed structure of the electron spin energy levels as well as on the spatial quantization of the spin motion. It is shown theoretically and experimentally that the NMR-PRE produced by integer spins can be influenced strongly by the small intradoublet zero-field splittings, i.e., the splittings between the components of the non-Kramers doublets, which are produced by noncylindrical components of the crystal field potential. These small splittings produce relatively low-frequency oscillations in the dipolar field associated with (the spin component along the molecule-fixed ẑ axis). These motions decouple the nuclear spin from the electron spin, thereby depressing, in some cases very strongly, the NMR-PRE. The presence of a relatively small Zeeman field, comparable in magnitude to the intradoublet spacing but small compared to the larger interdoublet zfs splittings, causes a major change in the spin wave functions which has profound effects on the motions of the electron spin. When the Zeeman energy exceeds the small zfs splitting, the oscillatory motion of damps out, with the result that the electron spin couples more effectively to the nuclear spin, providing a more efficient NMR relaxation pathway. NMR-PRE data are presented for the S=1 complex Ni(II)(o-pda)2Cl2 (o-pda=ortho-phenylenediamine) which confirm the

  6. Effects of an electric field on interaction of aromatic systems.

    PubMed

    Youn, Il Seung; Cho, Woo Jong; Kim, Kwang S

    2016-04-30

    The effect of uniform external electric field on the interactions between small aromatic compounds and an argon atom is investigated using post-HF (MP2, SCS-MP2, and CCSD(T)) and density functional (PBE0-D3, PBE0-TS, and vdW-DF2) methods. The electric field effect is quantified by the difference of interaction energy calculated in the presence and absence of the electric field. All the post-HF methods describe electric field effects accurately although the interaction energy itself is overestimated by MP2. The electric field effect is explained by classical electrostatic models, where the permanent dipole moment from mutual polarization mainly determines its sign. The size of π-conjugated system does not have significant effect on the electric field dependence. We found out that PBE0-based methods give reasonable interaction energies and electric field response in every case, while vdW-DF2 sometimes shows spurious artifact owing to its sensitivity toward the real space electron density. © 2015 Wiley Periodicals, Inc. PMID:26696236

  7. Gate protective device for insulated gate field-effect transistors

    NASA Technical Reports Server (NTRS)

    Sunshine, R. A.

    1972-01-01

    Device, which protects insulated gate field-effect transistors, improves reliability through utilization of layers of conductive material on top of each alternating semiconductor material region. Separation of layers is necessary to prevent shorting out junctions between alternating regions.

  8. A Field-Effect Transistor (FET) model for ASAP

    NASA Technical Reports Server (NTRS)

    Ming, L.

    1965-01-01

    The derivation of the circuitry of a field effect transistor (FET) model, the procedure for adapting the model to automated statistical analysis program (ASAP), and the results of applying ASAP on this model are described.

  9. Magnetoreception in birds: the effect of radio-frequency fields.

    PubMed

    Wiltschko, Roswitha; Thalau, Peter; Gehring, Dennis; Nießner, Christine; Ritz, Thorsten; Wiltschko, Wolfgang

    2015-02-01

    The avian magnetic compass, probably based on radical pair processes, works only in a narrow functional window around the local field strength, with cryptochrome 1a as most likely receptor molecule. Radio-frequency fields in the MHz range have been shown to disrupt the birds' orientation, yet the nature of this interference is still unclear. In an immuno-histological study, we tested whether the radio-frequency fields interfere with the photoreduction of cryptochrome, but this does not seem to be the case. In behavioural studies, birds were not able to adjust to radio-frequency fields like they are able to adjust to static fields outside the normal functional range: neither a 2-h pre-exposure in a 7.0 MHz field, 480 nT, nor a 7-h pre-exposure in a 1.315 MHz field, 15 nT, allowed the birds to regain their orientation ability. This inability to adjust to radio-frequency fields suggests that these fields interfere directly with the primary processes of magnetoreception and therefore disable the avian compass as long as they are present. They do not have lasting adverse after-effects, however, as birds immediately after exposure to a radio-frequency field were able to orient in the local geomagnetic field. PMID:25540238

  10. Magnetoreception in birds: the effect of radio-frequency fields

    PubMed Central

    Wiltschko, Roswitha; Thalau, Peter; Gehring, Dennis; Nießner, Christine; Ritz, Thorsten; Wiltschko, Wolfgang

    2015-01-01

    The avian magnetic compass, probably based on radical pair processes, works only in a narrow functional window around the local field strength, with cryptochrome 1a as most likely receptor molecule. Radio-frequency fields in the MHz range have been shown to disrupt the birds' orientation, yet the nature of this interference is still unclear. In an immuno-histological study, we tested whether the radio-frequency fields interfere with the photoreduction of cryptochrome, but this does not seem to be the case. In behavioural studies, birds were not able to adjust to radio-frequency fields like they are able to adjust to static fields outside the normal functional range: neither a 2-h pre-exposure in a 7.0 MHz field, 480 nT, nor a 7-h pre-exposure in a 1.315 MHz field, 15 nT, allowed the birds to regain their orientation ability. This inability to adjust to radio-frequency fields suggests that these fields interfere directly with the primary processes of magnetoreception and therefore disable the avian compass as long as they are present. They do not have lasting adverse after-effects, however, as birds immediately after exposure to a radio-frequency field were able to orient in the local geomagnetic field. PMID:25540238

  11. Disentangling Effects of Nuclear Structure in Heavy Element Formation

    SciTech Connect

    Hinde, D. J.; Thomas, R. G.; Rietz, R. du; Diaz-Torres, A.; Dasgupta, M.; Brown, M. L.; Evers, M.; Gasques, L. R.; Rafiei, R.; Rodriguez, M. D.

    2008-05-23

    Forming the same heavy compound nucleus with different isotopes of the projectile and target elements allows nuclear structure effects in the entrance channel (resulting in static deformation) and in the dinuclear system to be disentangled. Using three isotopes of Ti and W, forming {sup 232}Cm, with measurement spanning the capture barrier energies, alignment of the heavy prolate deformed nucleus is shown to be the main reason for the broadening of the mass distribution of the quasifission fragments as the beam energy is reduced. The complex, consistently evolving mass-angle correlations that are observed carry more information than the integrated mass or angular distributions, and should severely test models of quasifission.

  12. Research on the climatic effects of nuclear winter: Final report

    SciTech Connect

    Dickinson, R.E.

    1986-12-03

    The National Center for Atmospheric Research (NCAR) has undertaken a series of research efforts to develop and implement improvements to the Community Climate Model (CCM) needed to make the model more applicable to studies of the climatic effects of nuclear war. The development of the model improvements has reached a stage where implementation may proceed, and several of the developed routines are being incorporated into the next approved version of the CCM (CCM1). Formal documentation is being completed describing the specific model improvements that have been successfully implemented. This final report includes the series of annual proposals and progress reports that have guided the project.

  13. Climate and chemistry effects of a regional scale nuclear conflict

    NASA Astrophysics Data System (ADS)

    Stenke, A.; Hoyle, C. R.; Luo, B.; Rozanov, E.; Gröbner, J.; Maag, L.; Brönnimann, S.; Peter, T.

    2013-05-01

    Previous studies have highlighted the severity of detrimental effects for life on Earth after an assumed regionally limited nuclear war. These effects are caused by climatic, chemical and radiative changes persisting for up to one decade. However, so far only a very limited number of climate model simulations have been performed, giving rise to the question how realistic previous computations have been. This study uses the coupled chemistry climate model (CCM) SOCOL, which belongs to a different family of CCMs than previously used, to investigate the consequences of such a hypothetical nuclear conflict. In accordance with previous studies, the present work assumes a scenario of a nuclear conflict between India and Pakistan, each applying 50 warheads with an individual blasting power of 15 kt ("Hiroshima size") against the major population centers, resulting in the emission of tiny soot particles, which are generated in the firestorms expected in the aftermath of the detonations. Substantial uncertainties related to the calculation of likely soot emissions, particularly concerning assumptions of target fuel loading and targeting of weapons, have been addressed by simulating several scenarios, with soot emissions ranging from 1 to 12 Tg. Their high absorptivity with respect to solar radiation leads to a tremendous self-lofting of the soot particles into the strato- and mesosphere, where they remain for several years. Consequently, the model suggests Earth's surface temperatures to drop by several degrees Celsius due to the shielding of solar irradiance by the soot, indicating a major global cooling. In addition, there is a substantial reduction of precipitation lasting 5 to 10 yr after the conflict, depending on the magnitude of the initial soot release. Extreme cold spells associated with massive sea ice formation are found during Northern Hemisphere winter, which expose the continental land masses of Northern America and Eurasia to chilling coldness. In the

  14. [Radiation-related health effects of major nuclear events].

    PubMed

    Orgiazzi, Jacques

    2015-01-01

    Three major nuclear events, the Hirosima and Nagasaki bombings and the Chernobyl and Fukushima catastrophes, have been selected to Illustrate the health consequences, observed or anticipated, of irradation of populations. Differences in doses and modalities of irradiation, with the combination of clinical epidemiology and dose estimates, recently revisited, allow for more accurate dose-effect relationship models of the risks. However, extrapolation to the low-doses (< 0.1 Gy) or very low-doses of these models obtained with doses ≥ 0.2 Gy remains hazardous. PMID:25842445

  15. Biological effects and exposure criteria for radiofrequency electromagnetic fields

    SciTech Connect

    Not Available

    1986-01-01

    This report, which begins with a discussion of fundamental studies at the molecular level, presents a review of the subject matter covered in NCRP Report No. 67 on mechanisms of interaction of radiofrequency electromagnetic (RFEM) fields with tissue. The discussion continues to progressively larger scales of interaction, beginning with macromolecular and cellular effects, chromosomal and mutagenic effects, and carcinogenic effects. The scope of the subject matter is then expanded to include systemic effects such as those on reproduction, growth, and development, hematopoiesis and immunology, endocrinology and autonomic nervous function, cardiovascular effects and cerebrovascular effects. The interaction of electromagnetic fields with the central nervous system and special senses is also discussed. Also included are epidemiological studies, a discussion of thermoregulation, and a history of therapeutic applications of RFEM fields. The report concludes with human exposure criteria and rationale.

  16. Isotopic Effects in Nuclear Fragmentation and GCR Transport Problems

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.

    2002-01-01

    Improving the accuracy of the galactic cosmic ray (GCR) environment and transport models is an important goal in preparing for studies of the projected risks and the efficiency of potential mitigations methods for space exploration. In this paper we consider the effects of the isotopic composition of the primary cosmic rays and the isotopic dependence of nuclear fragmentation cross sections on GCR transport models. Measurements are used to describe the isotopic composition of the GCR including their modulation throughout the solar cycle. The quantum multiple-scattering approach to nuclear fragmentation (QMSFRG) is used as the data base generator in order to accurately describe the odd-even effect in fragment production. Using the Badhwar and O'Neill GCR model, the QMSFRG model and the HZETRN transport code, the effects of the isotopic dependence of the primary GCR composition and on fragment production for transport problems is described for a complete GCR isotopic-grid. The principle finding of this study is that large errors ( 100%) will occur in the mass-flux spectra when comparing the complete isotopic-grid (141 ions) to a reduced isotopic-grid (59 ions), however less significant errors 30%) occur in the elemental-flux spectra. Because the full isotopic-grid is readily handled on small computer work-stations, it is recommended that they be used for future GCR studies.

  17. Effects of persistent insecticides on beneficial soil arthropod in conventional fields compared to organic fields, puducherry.

    PubMed

    Anbarashan, Padmavathy; Gopalswamy, Poyyamoli

    2013-07-15

    The usage of synthetic fertilizers/insecticides in conventional farming has dramatically increased over the past decades. The aim of the study was to compare the effects of bio-pesticides and insecticides/pesticides on selected beneficial non targeted arthropods. Orders Collembola, Arachinida/Opiliones, Oribatida and Coleoptera were the main groups of arthropods found in the organic fields and Coleoptera, Oribatida, Gamasida and Collembola in conventional fields. Pesticides/insecticides had a significant effect on non-targeted arthropods order- Collembola, Arachinida/Opiliones, Hymenoptera and Thysonoptera were suppressed after pesticides/insecticides spraying. Bio-insecticides in organic fields had a non-significant effect on non targeted species and they started to increase in abundance after 7 days of spraying, whereas insecticide treatment in conventional fields had a significant long-term effect on non targeted arthropods and short term effect on pests/insects, it started to increase after 21 days of the spraying. These results indicate that insecticide treatment kept non targeted arthropods at low abundance. In conclusion, organic farming does not significantly affected the beneficial-non targeted arthropods biodiversity, whereas preventive insecticide application in conventional fields had significant negative effects on beneficial non targeted arthropods. Therefore, conventional farmers should restrict insecticide applications, unless pest densities reach the thresholds and more desirably can switch to organic farming practices. PMID:24505991

  18. Effects of Electromagnetic Fields on Fish and Invertebrates

    SciTech Connect

    Schultz, Irvin R.; Woodruff, Dana L.; Marshall, Kathryn E.; Pratt, William J.; Roesijadi, Guritno

    2010-10-13

    In this progress report, we describe the preliminary experiments conducted with three fish and one invertebrate species to determine the effects of exposure to electromagnetic fields. During fiscal year 2010, experiments were conducted with coho salmon (Onchrohychus kisutch), California halibut (Paralicthys californicus), Atlantic halibut (Hippoglossus hippoglossus), and Dungeness crab (Cancer magister). The work described supports Task 2.1.3: Effects on Aquatic Organisms, Subtask 2.1.3.1: Electromagnetic Fields.

  19. Effective field theory from modified gravity with massive modes

    NASA Astrophysics Data System (ADS)

    Capozziello, Salvatore; de Laurentis, Mariafelicia; Paolella, Mariacristina; Ricciardi, Giulia

    2015-10-01

    Massive gravitational modes in effective field theories can be recovered by extending General Relativity and taking into account generic functions of the curvature invariants, not necessarily linear in the Ricci scalar R. In particular, adopting the minimal extension of f(R) gravity, an effective field theory with massive modes is straightforwardly recovered. This approach allows to evade shortcomings like ghosts and discontinuities if a suitable choice of expansion parameters is performed.

  20. Diffraction patterns in ferrofluids: Effect of magnetic field and gravity

    NASA Astrophysics Data System (ADS)

    Radha, S.; Mohan, Shalini; Pai, Chintamani

    2014-09-01

    In this paper, we report the experimental observation of diffraction patterns in a ferrofluid comprising of Fe3O4 nanoparticles in hexane by a 10 mW He-Ne laser beam. An external dc magnetic field (0-2 kG) was applied perpendicular to the beam. The diffraction pattern showed a variation at different depths of the sample in both zero and applied magnetic field. The patterns also exhibit a change in shape and size as the external field is varied. This effect arises due to thermally induced self-diffraction under the influence of gravity and external magnetic field.

  1. Novel electric field effects on Landau levels in graphene.

    PubMed

    Lukose, Vinu; Shankar, R; Baskaran, G

    2007-03-16

    A new effect in graphene in the presence of crossed uniform electric and magnetic fields is predicted. Landau levels are shown to be modified in an unexpected fashion by the electric field, leading to a collapse of the spectrum, when the value of electric to magnetic field ratio exceeds a certain critical value. Our theoretical results, strikingly different from the standard 2D electron gas, are explained using a "Lorentz boost," and as an "instability of a relativistic quantum field vacuum." It is a remarkable case of emergent relativistic type phenomena in nonrelativistic graphene. We also discuss few possible experimental consequence. PMID:17501075

  2. The effect of temperature and pairing on nuclear pseudospin symmetry

    SciTech Connect

    Malheiro, M.; Lisboa, R.; Carlson, B. V.; Alberto, P.

    2009-06-03

    We study the effects of temperature andpairing on pseudospin symmetry in spherical and deformed nucleus using the Dirac-Hartree-Bogoliubov (DHB) formalism. We include temperature in the DHB equation using the Matsubara formalism and analyze changes in the neutron single particle levels with the temperature. We show that the effect of temperature on the pseudospin energy splitting is small. We find that this splitting decreases at high temperatures and that pseudospin partners are almost degenerate in deformed hot nuclei, indicating the dependence of pseudospin symmetry on the nuclear surface. Furthermore, for reasonable values of the pairing interaction, we also show that pairing does not affect the pseudospin symmetry in deformed nuclei. Finally, we find that the effect of temperature on pseudospin doublets is more pronounced in spherical nuclei than in deformed ones.

  3. Endocrinological effects of strong 60-Hz electric fields on rats

    SciTech Connect

    Free, M.J.; Kaune, W.T.; Phillips, R.D.; Cheng, H.C.

    1981-01-01

    Adult male rats were exposed or sham-exposed to 60-Hz electric fields without spark discharges, ozone, or significant levels or other secondary variables. No effects were discharges, ozone, or significant levels of other secondary variables. No effects were observed on body weights or plasma hormone levels after 30 days of exposure at an effective field strength of 68 kV/m. After 120 days of exposure (effective field strength = 64 kV/m), effects were inconsistent, with signficant reductions in body weight and plasma levels of follicle-stimulating hormone and corticosterone occurring in one replicate experiment but not in the other. Plasma testosterone levels were significantly reduced after 120 days of exposure in one experiment, with a similar but not statistically significant reduction in a replicate experiment. Weanling rats, exposed or sham-exposed in electric fields with an effective field strength of 80 kV/m from 20 to 56 days of age, exhibited identical or closely similar growth trends in body and organ weights. Hormone levels in exposed and sham-exposed groups were also similar. However, there was an apparent phase shift between the two groups in the cyclic variations of concentrations of hormones at different stages of development, particularly with respect to follicle-stimulating hormone and corticosterone. We concluded that 60-Hz electric fields may bring about subtle changes in the endocrine system of rats, and that these changes may be related to alterations in episodic rhythms.

  4. Induced magnetic-field effects in inductively coupled plasmas

    SciTech Connect

    Cohen, R.H.; Rognlien, T.D.

    1995-11-04

    In inductive plasma sources, the rapid spatial decay of the electric field arising from the skin effect produces a large radio frequency (RF) magnetic field via Faraday`s law. We previously determined that this magnetic field leads to a reduction of the electron density in the skin region, as well as a reduction in the collisionless heating rate. The electron deficit leads to the formation of an electrostatic potential which pulls electrons in to restore quasineutrality. Here we calculate the electron density including both the induced and electrostatic fields. If the wave frequency is not too low, the ions respond only to the averaged fields, and hence the electrostatic field is oscillatory, predominantly at the second harmonic of the applied field. We calculate the potential required to establish a constant electron density, and compare with numerical orbit-code calculations. For times short compared to ion transit times, the quasineutral density is just the initial ion density. For timescales long enough that the ions can relax, the density profile can be found from the solution of fluid equations with an effective (ponderomotive-like) potential added. Although the time-varying electrostatic potential is an extra source of heating, the net effect of the induced magnetic and electrostatic fields through trapping, early turning, and direct heating is a significant reduction in collisionless heating for parameters of interest.

  5. Topological magnetoelectric effects in microwave far-field radiation

    NASA Astrophysics Data System (ADS)

    Berezin, M.; Kamenetskii, E. O.; Shavit, R.

    2016-07-01

    Similar to electromagnetism, described by the Maxwell equations, the physics of magnetoelectric (ME) phenomena deals with the fundamental problem of the relationship between electric and magnetic fields. Despite a formal resemblance between the two notions, they concern effects of different natures. In general, ME-coupling effects manifest in numerous macroscopic phenomena in solids with space and time symmetry breakings. Recently, it was shown that the near fields in the proximity of a small ferrite particle with magnetic-dipolar-mode (MDM) oscillations have the space and time symmetry breakings and the topological properties of these fields are different from the topological properties of the free-space electromagnetic fields. Such MDM-originated fields—called magnetoelectric (ME) fields—carry both spin and orbital angular momenta. They are characterized by power-flow vortices and non-zero helicity. In this paper, we report on observation of the topological ME effects in far-field microwave radiation based on a small microwave antenna with a MDM ferrite resonator. We show that the microwave far-field radiation can be manifested with a torsion structure where an angle between the electric and magnetic field vectors varies. We discuss the question on observation of the regions of localized ME energy in far-field microwave radiation.

  6. Effect of external fields in Axelrod's model of social dynamics

    NASA Astrophysics Data System (ADS)

    Peres, Lucas R.; Fontanari, José F.

    2012-09-01

    The study of the effects of spatially uniform fields on the steady-state properties of Axelrod's model has yielded plenty of counterintuitive results. Here, we reexamine the impact of this type of field for a selection of parameters such that the field-free steady state of the model is heterogeneous or multicultural. Analyses of both one- and two-dimensional versions of Axelrod's model indicate that the steady state remains heterogeneous regardless of the value of the field strength. Turning on the field leads to a discontinuous decrease on the number of cultural domains, which we argue is due to the instability of zero-field heterogeneous absorbing configurations. We find, however, that spatially nonuniform fields that implement a consensus rule among the neighborhood of the agents enforce homogenization. Although the overall effects of the fields are essentially the same irrespective of the dimensionality of the model, we argue that the dimensionality has a significant impact on the stability of the field-free homogeneous steady state.

  7. Determining diffusion coefficients of ionic liquids by means of field cycling nuclear magnetic resonance relaxometry

    SciTech Connect

    Kruk, D.; Meier, R.; Rössler, E. A.; Rachocki, A.; Korpała, A.; Singh, R. K.

    2014-06-28

    Field Cycling Nuclear Magnetic Resonance (FC NMR) relaxation studies are reported for three ionic liquids: 1-ethyl-3- methylimidazolium thiocyanate (EMIM-SCN, 220–258 K), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF{sub 4}, 243–318 K), and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF{sub 6}, 258–323 K). The dispersion of {sup 1}H spin-lattice relaxation rate R{sub 1}(ω) is measured in the frequency range of 10 kHz–20 MHz, and the studies are complemented by {sup 19}F spin-lattice relaxation measurements on BMIM-PF{sub 6} in the corresponding frequency range. From the {sup 1}H relaxation results self-diffusion coefficients for the cation in EMIM-SCN, BMIM-BF{sub 4}, and BMIM-PF{sub 6} are determined. This is done by performing an analysis considering all relevant intra- and intermolecular relaxation contributions to the {sup 1}H spin-lattice relaxation as well as by benefiting from the universal low-frequency dispersion law characteristic of Fickian diffusion which yields, at low frequencies, a linear dependence of R{sub 1} on square root of frequency. From the {sup 19}F relaxation both anion and cation diffusion coefficients are determined for BMIM-PF{sub 6}. The diffusion coefficients obtained from FC NMR relaxometry are in good agreement with results reported from pulsed- field-gradient NMR. This shows that NMR relaxometry can be considered as an alternative route of determining diffusion coefficients of both cations and anions in ionic liquids.

  8. Low-field nuclear magnetic resonance characterization of organic content in shales

    USGS Publications Warehouse

    Washburn, Kathryn E.; Birdwell, Justin E.; Seymour, Joseph D.; Kirkland, Catherine; Vogt, Sarah J.

    2013-01-01

    Low-field nuclear magnetic resonance (LF-NMR) relaxometry is a non-invasive technique commonly used to assess hydrogen-bearing fluids in petroleum reservoir rocks. Longitudinal T1 and transverse T2 relaxation time measurements made using LF-NMR on conventional reservoir systems provides information on rock porosity, pore size distributions, and fluid types and saturations in some cases. Recent improvements in LF-SNMR instrument electronics have made it possible to apply these methods to assess highly viscous and even solid organic phases within reservoir rocks. T1 and T2 relaxation responses behave very differently in solids and liquids, therefore the relationship between these two modes of relaxation can be used to differentiate organic phases in rock samples or to characterize extracted organic materials. Using T1-T2 correlation data, organic components present in shales, such as kerogen and bitumen, can be examined in laboratory relaxometry measurements. In addition, implementation of a solid-echo pulse sequence to refocus some types of T2 relaxation during correlation measurements allows for improved resolution of solid phase photons. LF-NMR measurements of T1 and T2 relaxation time correlations were carried out on raw oil shale samples from resources around the world. These shales vary widely in mineralogy, total organic carbon (TOC) content and kerogen type. NMR results were correlcated with Leco TOC and geochemical data obtained from Rock-Eval. There is excellent correlation between NMR data and programmed pyrolysis parameters, particularly TOC and S2, and predictive capability is also good. To better understand the NMR response, the 2D NMR spectra were compared to similar NMR measurements made using high-field (HF) NMR equipment.

  9. Field Demonstration of Slim-hole Borehole Nuclear Magnetic Resonance (NMR) Logging Tool for Groundwater Investigations

    NASA Astrophysics Data System (ADS)

    Walsh, D.; Turner, P.; Frid, I.; Shelby, R.; Grunewald, E. D.; Magnuson, E.; Butler, J. J.; Johnson, C. D.; Cannia, J. C.; Woodward, D. A.; Williams, K. H.; Lane, J. W.

    2010-12-01

    Nuclear magnetic resonance (NMR) methods provide estimates of free and bound water content and hydraulic conductivity, which are critically important for groundwater investigations. Borehole NMR tools have been available and widely used in the oil industry for decades, but only recently have been designed for small diameter boreholes typical of groundwater investigations. Field tests of an 89-mm-diameter borehole NMR logging tool are presented. This borehole NMR logging tool was developed for economical NMR logging of 100- to 200-mm-diameter boreholes, and specifically for characterizing hydraulic properties in the top 200 m of the subsurface. The tool has a vertical resolution of 0.5 m, a minimum echo spacing of 2.0 ms, and a radial depth of investigation of 178 to 203 mm, which typically is beyond the annulus of observation wells. It takes about 15 minutes to collect a data sample for each 0.5-m interval. The borehole NMR logging tool was field tested during spring 2010, in PVC-cased wells at sites in East Haddam and Storrs, Connecticut; Cape Cod, Massachusetts; Lexington, Nebraska; Lawrence, Kansas; and Rifle, Colorado. NMR logging yielded estimates of bound water, free water, and total-water content, as well as continuous distributions of water content versus transverse relaxation time (T2) at all depth levels. The derived water-content data were compared to the available ground-truth hydrogeologic data from each well, including drilling logs, neutron and other geophysical logs, and direct measurements of hydraulic conductivity. The results indicate that the borehole NMR logging tool provides information on porosity, pore-size distribution, and estimated hydraulic conductivity that cannot be duplicated by any other single geophysical logging tool.

  10. Effects of a magnetic field on the germination of plants

    NASA Astrophysics Data System (ADS)

    Hirota, Noriyuki; Nakagawa, Jun; Kitazawa, Koichi

    1999-04-01

    The effects of a nonuniform magnetic field on the germination of plants were studied. When a 10 T magnetic field was applied at the center of a superconducting magnet, a cucumber shoot germinating in a horizontal bore leaned towards the field center. In contrast, the root grew in the direction opposite the shoot. The observed result seemed to have occurred as a result of the magnetic force influencing the geotaxis of the cucumber. This idea was supported qualitatively by analysis results of the experimental data. Knowledge obtained in this study will be helpful for the evaluation of the effect of the magnetic field on living bodies and suggests the possibility of applying magnetic fields in other areas of research.

  11. TOPICAL REVIEW: Polarization effects in molecular mechanical force fields

    NASA Astrophysics Data System (ADS)

    Cieplak, Piotr; Dupradeau, François-Yves; Duan, Yong; Wang, Junmei

    2009-08-01

    The focus here is on incorporating electronic polarization into classical molecular mechanical force fields used for macromolecular simulations. First, we briefly examine currently used molecular mechanical force fields and the current status of intermolecular forces as viewed by quantum mechanical approaches. Next, we demonstrate how some components of quantum mechanical energy are effectively incorporated into classical molecular mechanical force fields. Finally, we assess the modeling methods of one such energy component—polarization energy—and present an overview of polarizable force fields and their current applications. Incorporating polarization effects into current force fields paves the way to developing potentially more accurate, though more complex, parameterizations that can be used for more realistic molecular simulations.

  12. Heavy nuclei confinement effect in a pulsed light field

    NASA Astrophysics Data System (ADS)

    Starodub, S. S.; Roshchupkin, S. P.

    2011-04-01

    It is a model theoretical work of the applied character in which: "Outside the framework of the dipole approximation (with an accuracy of about v/c) the effective interaction force between stripped uranium nuclei in the presence pulsed field of two laser waves extending towards each other is theoretically studied. It is shown that the effective interaction force between uranium nuclei, can become an attractive force on certain time intervals in the presence of the pulsed laser field. As a result the pulsed laser field can slow down backward motion of nuclei in 7 times."

  13. Effects of solar magnetic field on cosmic rays

    NASA Technical Reports Server (NTRS)

    Goncher, G. A.; Kolomeets, E. V.; Lyakhova, A. K.; Slyunyaeva, N. V.; Stekolnikov, N. V.

    1985-01-01

    Aspects of the problem of galactic cosmic ray propagation, including inversion of the solar total magnetic field and an analysis of data related to the heliomagnetic cycle are discussed. It is noted that the global structure of the solar magnetic field results in an additional flux of galactic cosmic rays generated by curvature and gradient drifts. An analysis of heliomagnetic cycle data shows that the latitudinal gradient results in a N-S asymmetry, with the amplitude of the effect growing with depth in the atmosphere. The inversion of the solar total magnetic field, drift effects, and other space distributions are found to contribute to a 22-year cycle of solar activity.

  14. Sandwich double gate vertical tunneling field-effect transistor

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Zhang, Wen-hao; Yu, Cheng-hao; Cao, Fei

    2016-05-01

    In this work, a sandwich vertical tunnel field effect transistor (SDG-VTFET) is presented and studied. Since the dominant carrier tunneling of SDG-VFET occurs in a direction that is in line with the gate field, high ON-state current and steep subthreshold slope are observed. Comparisons between SDG-VFET and double gate tunnel field effect transistor are made to clarify advantages of SDG-VTFET. The simulation results of our work show that SDG-VTFET has stronger gate control, steeper subthreshold slope and higher ON-state current. The device plays a promising candidate for future low power circuit applications.

  15. Effects of Magnetic Fields on Bar Substructures in Barred Galaxies

    NASA Astrophysics Data System (ADS)

    Kim, Woong-Tae

    2015-03-01

    To study the effects of magnetic fields on the properties of bar substructures, we run two-dimensional, ideal MHD simulations of barred galaxies under the influence of a non-axisymmetric bar potential. In the bar regions, magnetic fields reduce density compression in the dust-lane shocks, while removing angular momentum further from the gas at the shocks. This evidently results in a smaller and more distributed ring, and a larger mass inflows rate to the galaxy center in models with stronger magnetic fields. In the outer regions, an MHD dynamo due to the combined action of the bar potential and background shear operates, amplifying magnetic fields near the corotation resonance. In the absence of spiral arms, the amplified fields naturally shape into trailing magnetic arms with strong fields and low density. The reader is refereed to Kim & Stone (2012) for a detailed presentation of the simulation outcomes.

  16. Lattice Study of Magnetic Catalysis in Graphene Effective Field Theory

    NASA Astrophysics Data System (ADS)

    Winterowd, Christopher; Detar, Carleton; Zafeiropoulos, Savvas

    2016-03-01

    The discovery of graphene ranks as one of the most important developments in condensed matter physics in recent years. As a strongly interacting system whose low-energy excitations are described by the Dirac equation, graphene has many similarities with other strongly interacting field theories, particularly quantum chromodynamics (QCD). Graphene, along with other relativistic field theories, have been predicted to exhibit spontaneous symmetry breaking (SSB) when an external magnetic field is present. Using nonperturbative methods developed to study QCD, we study the low-energy effective field theory (EFT) of graphene subject to an external magnetic field. We find strong evidence supporting the existence of SSB at zero-temperature and characterize the dependence of the chiral condensate on the external magnetic field. We also present results for the mass of the Nambu-Goldstone boson and the dynamically generated quasiparticle mass that result from the SSB.

  17. Study of the effects of guide field on Hall reconnection

    SciTech Connect

    Tharp, T. D.; Yamada, M.; Ji, H.; Lawrence, E.; Dorfman, S.; Myers, C.; Yoo, J.; Huang, Y.-M.; Bhattacharjee, A.

    2013-05-15

    The results from guide field studies on the Magnetic Reconnection Experiment (MRX) are compared with results from Hall magnetohydrodynamic (HMHD) reconnection simulation with guide field. The quadrupole field, a signature of two-fluid reconnection at zero guide field, is modified by the presence of a finite guide field in a manner consistent with HMHD simulation. The modified Hall current profile contains reduced electron flows in the reconnection plane, which quantitatively explains the observed reduction of the reconnection rate. The present results are consistent with the hypothesis that the local reconnection dynamics is dominated by Hall effects in the collisionless regime of the MRX plasmas. While very good agreement is seen between experiment and simulations, we note that an important global feature of the experiments, a compression of the guide field by the reconnecting plasma, is not represented in the simulations.

  18. Magnetic Field Effect on the Stability of Flow Induced by a Rotating Magnetic Field

    NASA Technical Reports Server (NTRS)

    Mazuruk, K.; Volz, M. P.; Gillies, D. C.

    1999-01-01

    A linear stability analysis has been performed for the flow induced by a rotating magnetic field in a cylindrical column filled with electrically conducting fluid. The first transition is time- independent and results in the generation of Taylor vortices. The critical value of the magnetic Taylor number has been examined as a function of the strength of the transverse rotating magnetic field, the strength of an axial static magnetic field, and thermal buoyancy. Increasing the transverse field increases the critical magnetic Taylor number and decreases the aspect ratio of the Taylor vortices at the onset of instability. An increase in the axial magnetic field also increases the critical magnetic Taylor number but increases the aspect ratio of the Taylor vortices. Thermal buoyancy is found to have only a negligible effect on the onset of instability.

  19. Magnetic Field Effect on the Stability of Flow Induced by a Rotating Magnetic Field

    NASA Technical Reports Server (NTRS)

    Mazuruk, K.; Gillies, D. C.; Volz, M. P.

    1999-01-01

    A linear stability analysis has been performed for the flow induced by a rotating magnetic field in a cylindrical column filled with electrically conducting fluid. The first transition is time-independent and results in the generation of Taylor vortices. The critical value of the magnetic Taylor number has been examined as a function of the strength of the transverse rotating magnetic field, the strength of an axial static magnetic field, and thermal buoyancy. Increasing the transverse field increases the critical magnetic Taylor number and decreases the aspect ratio of the Taylor vortices at the onset of instability. An increase in the axial magnetic field also increases the critical magnetic Taylor number but increases the aspect ratio of the Taylor vortices. Thermal buoyancy is found to have only a negligible effect on the onset of instability.

  20. Effect of the interactions and environment on nuclear activity

    NASA Astrophysics Data System (ADS)

    Sabater, J.; Best, P. N.; Argudo-Fernández, M.

    2013-03-01

    We present a study of the prevalence of optical and radio nuclear activity with respect to the environment and interactions in a sample of the Sloan Digital Sky Survey (SDSS) galaxies. The aim is to determine the independent effects of distinct aspects of source environment on the triggering of different types of nuclear activity. We defined a local density parameter and a tidal force estimator and used a cluster richness estimator from the literature to trace different aspects of environment and interaction. The possible correlations between the environmental parameters were removed using a principal component analysis. By far, the strongest trend found for the active galactic nuclei (AGN) fractions, of all AGN types, is with galaxy mass. We therefore applied a stratified statistical method that takes into account the effect of possible confounding factors like the galaxy mass. We found that (at fixed mass) the prevalence of optical AGN is a factor of 2-3 lower in the densest environments, but increases by a factor of ˜2 in the presence of strong one-on-one interactions. These effects are even more pronounced for star-forming nuclei. The importance of galaxy interactions decreases from star-forming nuclei to Seyferts to low-ionization nuclear emission-line regions to passive galaxies, in accordance with previous suggestions of an evolutionary time-sequence. The fraction of radio AGN increases very strongly (by nearly an order of magnitude) towards denser environments, and is also enhanced by galaxy interactions. Overall, the results agree with a scenario in which the mechanisms of accretion into the black hole are determined by the presence and nature of a supply of gas, which in turn is controlled by the local density of galaxies and their interactions. A plentiful cold gas supply is required to trigger star formation, optical AGN and radiatively efficient radio AGN. This is less common in the cold-gas-poor environments of groups and clusters, but is enhanced by