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Sample records for low-energy pion-pion scattering

  1. Pion-pion scattering amplitude

    SciTech Connect

    Pelaez, J.R.; Yndurain, F.J.

    2005-04-01

    We obtain reliable {pi}{pi} scattering amplitudes consistent with experimental data, both at low and high energies, and fulfilling appropriate analyticity properties. We do this by first fitting experimental low energy (s{sup 1/2}{<=}1.42 GeV) phase shifts and inelasticities with expressions that incorporate analyticity and unitarity. In particular, for the S wave with isospin 0, we discuss in detail several sets of experimental data. This provides low energy partial wave amplitudes that summarize the known experimental information. Then, we impose Regge behavior as follows from factorization and experimental data for the imaginary parts of the scattering amplitudes at higher energy, and check fulfillment of dispersion relations up to 0.925 GeV. This allows us to improve our fits. The ensuing {pi}{pi} scattering amplitudes are then shown to verify dispersion relations up to 1.42 GeV, as well as s-t-u crossing sum rules and other consistency conditions. The improved parametrizations therefore provide a reliable representation of pion-pion amplitudes with which one can test chiral perturbation theory calculations, pionium decays, or use as input for CP-violating K decays. In this respect, we find [a{sub 0}{sup (0)}-a{sub 0}{sup (2)}]{sup 2}=(0.077{+-}0.008)M{sub {pi}}{sup -2} and {delta}{sub 0}{sup (0)}(m{sub K}{sup 2})-{delta}{sub 0}{sup (2)}(m{sub K}{sup 2})=52.9{+-}1.6{sup o}.

  2. Pion-pion scattering amplitude. III. Improving the analysis with forward dispersion relations and Roy equations

    SciTech Connect

    Kaminski, R.; Pelaez, J. R.; Yndurain, F. J.

    2008-03-01

    We complete and improve the fits to experimental {pi}{pi} scattering amplitudes, both at low and high energies, that we performed in the previous papers of this series. We then verify that the corresponding amplitudes satisfy analyticity requirements, in the form of partial wave analyticity at low energies, forward dispersion relations (FDR) at all energies, and Roy equations belowKK threshold; the first by construction, the last two, inside experimental errors. Then we repeat the fits including as constraints FDR and Roy equations. The ensuing central values of the various scattering amplitudes verify very accurately FDR and, especially, Roy equations, and change very little from what we found by just fitting data, with the exception of the D2 wave phase shift, for which one parameter moves by 1.5{sigma}. These improved parametrizations therefore provide a reliable representation of pion-pion amplitudes with which one can test various physical relations. We also present a list of low energy parameters and other observables. In particular, we find a{sub 0}{sup (0)}=0.223{+-}0.009M{sub {pi}}{sup -1}, a{sub 0}{sup (2)}=-0.0444{+-}0.0045M{sub {pi}}{sup -1}, and {delta}{sub 0}{sup (0)}(m{sub K}{sup 2})-{delta}{sub 0}{sup (2)}(m{sub K}{sup 2})=50.9{+-}1.2{sup o}.

  3. Low energy scattering with a nontrivial pion

    SciTech Connect

    Fariborz, Amir H.

    2007-12-01

    An earlier calculation in a generalized linear sigma model showed that the well-known current algebra formula for low energy pion-pion scattering held even though the massless Nambu Goldstone pion contained a small admixture of a two-quark two-antiquark field. Here we turn on the pion mass and note that the current algebra formula no longer holds exactly. We discuss this small deviation and also study the effects of a SU(3) symmetric quark mass type term on the masses and mixings of the eight SU(3) multiplets in the model. We calculate the s-wave scattering lengths, including the beyond current algebra theorem corrections due to the scalar mesons, and observe that the effect of the scalar mesons is to improve the agreement with experiment. In the process, we uncover the way in which linear sigma models give controlled corrections (due to the presence of scalar mesons) to the current algebra scattering formula. Such a feature is commonly thought to exist only in the nonlinear sigma model approach.

  4. Entanglement creation in low-energy scattering

    SciTech Connect

    Weder, Ricardo

    2011-12-15

    We study the entanglement creation in the low-energy scattering of two particles in three dimensions, for a general class of interaction potentials that are not required to be spherically symmetric. The incoming asymptotic state, before the collision, is a product of two normalized Gaussian states. After the scattering, the particles are entangled. We take as a measure of the entanglement the purity of one of them. We provide a rigorous explicit computation, with error bound, of the leading order of the purity at low energy. The entanglement depends strongly on the difference of the masses. It takes its minimum when the masses are equal, and it increases rapidly with the difference of the masses. It is quite remarkable that the anisotropy of the potential gives no contribution to the leading order of the purity, in spite of the fact that entanglement is a second-order effect.

  5. Low-energy pion-nucleon scattering

    SciTech Connect

    Gibbs, W.R.; Ai, L.; Kaufmann, W.B.

    1998-02-01

    An analysis of low-energy charged pion-nucleon data from recent {pi}{sup {plus_minus}}p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f{sup 2}=0.0756{plus_minus}0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P{sub 31} and P{sub 13} partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the {Sigma} term. Off-shell amplitudes are also provided. {copyright} {ital 1998} {ital The American Physical Society}

  6. Low-energy pion-nucleon scattering

    NASA Astrophysics Data System (ADS)

    Gibbs, W. R.; Ai, Li; Kaufmann, W. B.

    1998-02-01

    An analysis of low-energy charged pion-nucleon data from recent π+/-p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f2=0.0756+/-0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P31 and P13 partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the Σ term. Off-shell amplitudes are also provided.

  7. Low Energy Electron Scattering from Fuels

    NASA Astrophysics Data System (ADS)

    Lopes, M. Cristina A.

    2012-06-01

    We report an investigation of processes that occur during the ignition of the plasma and its consequences in post-discharge time for an internal combustion engine, in order to find the appropriate parameters to be used in cars that operate with lean mixtures air-fuel. The relevance of this theme has attracted much attention, and has been one of the subjects of collaboration between experimental and theoretical groups in the USA and Brazil. We have produced some basic information necessary to modeling spark ignition in alcohol- fuelled engines. Total cross sections of electron scattering by methanol and ethanol molecules were obtained, using the linear transmission method based on the Beer-Lambert law to first approximation. Measurements and calculations of differential cross sections for low-energy (rotationally unresolved) electron scattering were also obtained, for scattering angles of 5 --130 . The measurements were taken using the relative flow method with an aperture source, and calculations using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons. Additionally to these, computer simulation studies of electronic discharge in mixtures of ethanol were performed, using a Zero-Dimensional Plasma Kinetic solver. Previous reported models for combustion of ethanol and cross sections data for momentum transfer of electron collisions with ethanol were used. The time evolutions of the main species densities are reported and the ignition time delay discussed.

  8. Low Energy Electron Scattering from Fuels

    NASA Astrophysics Data System (ADS)

    Lopes, M. C. A.; Silva, D. G. M.; Bettega, M. H. F.; da Costa, R. F.; Lima, M. A. P.; Khakoo, M. A.; Winstead, C.; McKoy, V.

    2012-11-01

    In order to understand and optimize processes occurring during the ignition of plasma and its consequences in post-discharge for an internal combustion engine, especially considering the spark plug, we have produced in this work some basic information necessary to modeling spark ignition in alcohol- fuelled engines. Total cross sections of electron scattering by methanol and ethanol molecules in the energy range from 60 to 500 eV are reported, using the linear transmission method based on the Beer-Lambert law to first approximation. Aditionally to that, measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering were also discussed, for impact energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°-130°. The measurements were obtained using the relative flow method with an aperture source, and calculations using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons.

  9. Low-energy electron scattering from cyanamide

    NASA Astrophysics Data System (ADS)

    Wang, Kedong; Guo, Shuangcheng; Meng, Ju; Huang, Xiaotian; Wang, Yongfeng

    2016-09-01

    The low-energy electron collisions with cyanamide molecule are investigated by using the UK molecular R -matrix codes for electron energies ranging from 0.01 eV to 10 eV. Three models including static-exchange, static-exchange plus polarization, and close-coupling (CC) approximations are employed to reveal the dynamic interaction. Elastic (integrated and differential), momentum-transfer, and excitation cross sections from the ground state to the three low-lying electron excited states have been presented. Two shape resonances, two core-excited resonances, and two Feshbach resonances are detected in the CC approximation. The role of active space in the target and scattering problem including the resonances is discussed. The precise resonance parameters are found to be sensitive to the treatment of polarization effects employed. These resonances may be responsible for the fragments observed in a recent experiment of the dissociative electron attachments to cyanamide. Since the cyanamide molecule has a large permanent dipole moment, a Born closure procedure is used to account for the contribution of partial waves higher than l =4 to obtain converged cross sections.

  10. Parity violation in low-energy neutron-deuteron scattering

    SciTech Connect

    Song, Young-Ho; Gudkov, Vladimir; Lazauskas, Rimantas

    2011-01-15

    Parity-violating effects for low-energy elastic neutron deuteron scattering are calculated for Desplanques, Donoghue, and Holstein (DDH) and effective field theory types of weak potentials in a distorted-wave Born approximation, using realistic hadronic strong interaction wave functions, obtained by solving three-body Faddeev equations in configuration space. The resulting relation between physical observables and low-energy constants can be used to fix low-energy constants from experiments. Potential model dependencies of parity-violating effects are discussed.

  11. Low-energy scattering of electrons and positrons in liquids

    NASA Technical Reports Server (NTRS)

    Schrader, D. M.

    1990-01-01

    The scattering of low energy electrons and positrons is described for the liquid phase and compared and contrasted with that for the gas phase. Similarities as well as differences are noted. The loci of scattering sites, called spurs in the liquid phase, are considered in detail. In particular, their temporal and spatial evolution is considered from the point of view of scattering. Two emphases are made: one upon the stochastic calculation of the distribution of distances required for slowing down to thermal velocities, and the other upon the calculation of cross sections for energy loss by means of quantum mechanics.

  12. Scattering of low-energy neutrinos on atomic shells

    SciTech Connect

    Babič, Andrej; Šimkovic, Fedor

    2015-10-28

    We present a derivation of the total cross section for inelastic scattering of low-energy solar neutrinos and reactor antineutrinos on bound electrons, resulting in a transition of the electron to an excited state. The atomic-shell structure of various chemical elements is treated in terms of a nonrelativistic approximation. We estimate the interaction rates for modern neutrino detectors, in particular the Borexino and GEMMA experiments. We establish that in these experiments the effect can be safely neglected, but it could be accessible to future large-volume neutrino detectors with low energy threshold.

  13. Exclusive measurements of pion nucleon going to pion pion nucleon

    NASA Astrophysics Data System (ADS)

    Kermani, Mohammad Arjomand

    The pion induced pion production reactions π±p/toπ±π+n were studied at projectile incident energies of 223, 243, 264, 284, and 305 MeV. The Canadian High Acceptance Orbit Spectrometer (CHAOS) was used to detected the charged particles, which originated from the interaction of the incident pion beam with a cryogenic liquid hydrogen target. The experimental results are presented in the form of single, double and triple differential cross sections. Total cross sections obtained by integrating the differential quantities are also reported. The experimental data, namely the π-p/toπ-π+n double differential cross sections, were used as input to the Chew-Low extrapolation procedure which was utilized to determine on-shell π+π- elastic scattering cross sections in the near threshold region. The Chew-Low results (the extrapolated πpi cross sections) were then used in a dispersion analysis (Roy equations) to obtain the πpi isospin zero S-wave scattering length. We find a00=0.209/pm 0.011μ-1. In addition, the invariant mass distributions from the (π+π-) channel were fitted to determine the model parameters for the extended model of Oset and Vicente-Vacas. We find that the model parameters obtained from fitting the (π+π-) data do not describe the invariant mass distributions in the (π+π+) channel.

  14. Rashba scattering in the low-energy limit

    NASA Astrophysics Data System (ADS)

    Hutchinson, Joel; Maciejko, Joseph

    2016-06-01

    We study potential scattering in a two-dimensional electron gas with Rashba spin-orbit coupling in the limit that the energy of the scattering electron approaches the bottom of the lower spin-split band. Focusing on two spin-independent circularly symmetric potentials, an infinite barrier and a delta-function shell, we show that scattering in this limit is qualitatively different from both scattering in the higher spin-split band and scattering of electrons without spin-orbit coupling. The scattering matrix is purely off-diagonal with both off-diagonal elements equal to one, and all angular momentum channels contribute equally; the differential cross section becomes increasingly peaked in the forward and backward scattering directions; the total cross section exhibits quantized plateaus. These features are independent of the details of the scattering potentials, and we conjecture them to be universal. Our results suggest that Rashba scattering in the low-energy limit becomes effectively one-dimensional.

  15. Low-energy potential scattering in two and three dimensions

    SciTech Connect

    Khuri, N. N.; Martin, Andre; Richard, J.-M.; Wu, T. T.

    2009-07-15

    Conditions are established for the existence of a scattering length and an effective range in the low-energy expansion of the S-wave phase shift of a central potential in two and three dimensions. The behavior of the phase shift as a function of the momentum is also derived for longer-range power-law potentials which do not fulfill these conditions.

  16. Elastic positron-cadmium scattering at low energies

    SciTech Connect

    Bromley, M. W. J.; Mitroy, J.

    2010-05-15

    The elastic and annihilation cross sections for positron-cadmium scattering are reported up to the positronium-formation threshold (at 2.2 eV). The low-energy phase shifts for the elastic scattering of positrons from cadmium were derived from the bound and pseudostate energies of a very large basis configuration-interaction calculation of the e{sup +}-Cd system. The s-wave binding energy is estimated to be 126{+-}42 meV, with a scattering length of A{sub scat}=(14.2{+-}2.1)a{sub 0}, while the threshold annihilation parameter, Z{sub eff}, was 93.9{+-}26.5. The p-wave phase shift exhibits a weak shape resonance that results in a peak Z{sub eff} of 91{+-}17 at a collision energy of about 490{+-}50 meV.

  17. Virtual Compton scattering off the nucleon at low energies

    SciTech Connect

    Scherer, S.; Korchin, A.Y.; Koch, J.H.

    1996-08-01

    We investigate the low-energy behavior of the four-point Green{close_quote}s function {Gamma}{sup {mu}{nu}} describing virtual Compton scattering off the nucleon. Using Lorentz invariance, gauge invariance, and crossing symmetry, we derive the leading terms of an expansion of the operator in the four-momenta {ital q} and {ital q}{sup {prime}} of the initial and final photon, respectively. The model-independent result is expressed in terms of the electromagnetic form factors of the free nucleon, i.e., on-shell information which one obtains from electron-nucleon scattering experiments. Model-dependent terms appear in the operator at {ital O}({ital q}{sub {alpha}}{ital q}{sub {beta}}{sup {prime}}), whereas the orders {ital O}({ital q}{sub {alpha}}{ital q}{sub {beta}}) and {ital O}({ital q}{sub {alpha}}{sup {prime}}{ital q}{sub {beta}}{sup {prime}}) are contained in the low-energy theorem for {Gamma}{sup {mu}{nu}}, i.e., no new parameters appear. We discuss the leading terms of the matrix element and comment on the use of on-shell equivalent electromagnetic vertices in the calculation of {open_quote}{open_quote}Born terms{close_quote}{close_quote} for virtual Compton scattering. {copyright} {ital 1996 The American Physical Society.}

  18. Low-Energy Elastic Electron Scattering by Atomic Oxygen

    NASA Technical Reports Server (NTRS)

    Zatsarinny O.; Bartschat, K.; Tayal, S. S.

    2006-01-01

    The B-spline R-matrix method is employed to investigate the low-energy elastic electron scattering by atomic oxygen. Flexible non-orthogonal sets of radial functions are used to construct the target description and to represent the scattering functions. A detailed investigation regarding the dependence of the predicted partial and total cross sections on the scattering model and the accuracy of the target description is presented. The predicted angle-integrated elastic cross sections are in good agreement with experiment, whereas significant discrepancies are found in the angle-differential elastic cross sections near the forward direction. .The near-threshold results are found to strongly depend on the treatment of inner-core short-range correlation effects in the target description, as well as on a proper account of the target polarizability. A sharp increase in the elastic cross sections below 1 eV found in some earlier calculations is judged to be an artifact of an unbalanced description of correlation in the N-electron target structure and the (N+l)-electron-collision problems.

  19. Low-Energy Electron Scattering by Sugarcane Lignocellulosic Biomass Molecules

    NASA Astrophysics Data System (ADS)

    Oliveira, Eliane; Sanchez, Sergio; Bettega, Marcio; Lima, Marco; Varella, Marcio

    2012-06-01

    The use of second generation (SG) bioethanol instead of fossil fuels could be a good strategy to reduce greenhouse gas emissions. However, the efficient production of SG bioethanol has being a challenge to researchers around the world. The main barrier one must overcome is the pretreatment, a very important step in SG bioethanol aimed at breaking down the biomass and facilitates the extraction of sugars from the biomass. Plasma-based treatment, which can generate reactive species, could be an interesting possibility since involves low-cost atmospheric-pressure plasma. In order to offer theoretical support to this technique, the interaction of low-energy electrons from the plasma with biomass is investigated. This study was motived by several works developed by Sanche et al., in which they understood that DNA damage arises from dissociative electron attachment, a mechanism in which electrons are resonantly trapped by DNA subunits. We will present elastic cross sections for low-energy electron scattering by sugarcane biomass molecules, obtained with the Schwinger multichannel method. Our calculations indicate the formation of π* shape resonances in the lignin subunits, while a series of broad and overlapping σ* resonances are found in cellulose and hemicellulose subunits. The presence of π* and σ* resonances could give rise to direct and indirect dissociation pathways in biomass. Then, theoretical resonance energies can be useful to guide the plasma-based pretreatment to break down specific linkages of interest in biomass.

  20. Inelastic pion scattering by /sup 13/C at low energies

    SciTech Connect

    Mitchell, J.H.

    1987-03-01

    Angular distributions for inelastically scattered pions were obtained for several states in /sup 13/C at an incident energy of 65 MeV. The data include results from both ..pi../sup +/ and ..pi../sup -/ measurements. In addition, ..pi../sup -/ measurements were made at T/sub ..pi../ = 50 MeV at one angle to give a two point fixed-q excitation function. The data are compared to theory and the data of others. As might be expected, medium corrections are shown to be considerably more important at low energies than at resonance. This is true for inelastic transitions of multipolarity 0,2 and 3. Parameters derived from an analysis of elastic pion scattering and SCX data also provide an adequate description of the inelastic transitions. The charge asymmetry in the cross sections for the 9/2/sup +/ state that was seen at resonance persists at these energies. This result is consistent with an impulse approximation treatment of the spin-flip amplitude. This is true even though the incoming energy of the pions is far below the range where the validity of an impulse treatment is expected. 65 refs., 45 figs.

  1. Deconstruction and elastic {pi}{pi} scattering in Higgsless models

    SciTech Connect

    Chivukula, R. Sekhar; Simmons, Elizabeth H.; He, Hong-Jian; Kurachi, Masafumi; Tanabashi, Masaharu

    2007-02-01

    We study elastic pion-pion scattering in global linear moose models and apply the results to a variety of Higgsless models in flat and anti-de Sitter (AdS) space using the equivalence theorem. In order to connect the global moose to Higgsless models, we first introduce a block-spin transformation which corresponds, in the continuum, to the freedom to perform coordinate transformations in the Higgsless model. We show that it is possible to make an 'f-flat' deconstruction in which all of the f-constants f{sub j} of the linear moose model are identical; the phenomenologically relevant f-flat models are those in which the coupling constants of the groups at either end of the moose are small--corresponding to the global linear moose. In studying pion-pion scattering, we derive various sum rules, including one analogous to the Kawarabayashi-Suzuki-Riazuddin-Fayyazuddin (KSRF) relation, and use them in evaluating the low-energy and high-energy forms of the leading elastic partial-wave scattering amplitudes. We obtain elastic unitarity bounds as a function of the mass of the lightest KK mode and discuss their physical significance.

  2. Deconstruction and elastic ππ scattering in Higgsless models

    NASA Astrophysics Data System (ADS)

    Chivukula, R. Sekhar; Simmons, Elizabeth H.; He, Hong-Jian; Kurachi, Masafumi; Tanabashi, Masaharu

    2007-02-01

    We study elastic pion-pion scattering in global linear moose models and apply the results to a variety of Higgsless models in flat and anti-de Sitter (AdS) space using the equivalence theorem. In order to connect the global moose to Higgsless models, we first introduce a block-spin transformation which corresponds, in the continuum, to the freedom to perform coordinate transformations in the Higgsless model. We show that it is possible to make an “f-flat” deconstruction in which all of the f-constants fj of the linear moose model are identical; the phenomenologically relevant f-flat models are those in which the coupling constants of the groups at either end of the moose are small—corresponding to the global linear moose. In studying pion-pion scattering, we derive various sum rules, including one analogous to the Kawarabayashi-Suzuki-Riazuddin-Fayyazuddin (KSRF) relation, and use them in evaluating the low-energy and high-energy forms of the leading elastic partial-wave scattering amplitudes. We obtain elastic unitarity bounds as a function of the mass of the lightest KK mode and discuss their physical significance.

  3. Low-energy elastic differential scattering of He/++/ by He.

    NASA Technical Reports Server (NTRS)

    Lam, S. K.; Doverspike, L. D.; Champion, R. L.

    1973-01-01

    Experimental results are developed for the relative elastic differential scattering of He(++) by He for collision energies in the range 4 equal to or less than E equal to or less than 75 eV. In the analysis of the data, semiclassical considerations are utilized, assuming that the dynamics of the scattering is governed solely by the B and E states of He2(++). It is shown that existing ab initio calculations for the intermolecular potentials predict differential cross sections which are not in particularly good agreement with the experimental data.

  4. Bremsstrahlung from nuclear scattering at low energy near a resonance

    NASA Astrophysics Data System (ADS)

    Trail, C. C.; Lesser, P. M. S.; Liou, M. K.

    1984-04-01

    A program to contribute to the general understanding of nuclear reactions by determining as many of the off-shell properties of the proton-nucleus interaction as possible through the study of the proton-nucleus bremsstrahlung process is discussed. The limits of validity of a model independent analysis of these reactions in the neighborhood of a resonance or a breakup threshold are sought. The differences between this analysis and the data is utilized to elucidate those off-shell constraints which any valid proton-nucleus model interaction must satisfy. The bremsstrahlung process provides a method for determining the off-shell properties of the proton-nucleus potential, and the Brooklyn College program offers a unique opportunity to measure these crucial aspects of the low energy proton-nucleus interaction.

  5. Low-energy Scattering of Positronium by Atoms

    NASA Technical Reports Server (NTRS)

    Ray, Hasi

    2007-01-01

    The survey reports theoretical studies involving positronium (Ps) - atom scattering. Investigations carried out in last few decades have been briefly reviewed in this article. A brief description of close-coupling approximation (CCA), the first-Born approximation (FBA) and the Born-Oppenheimer approximation (BOA) for Ps-Atom systems are made. The CCA codes of Ray et a1 [1-6] are reinvestigated using very fine mesh-points to search for resonances. The article advocates the need for an extended basis set & a systematic study using CCAs.

  6. Elastic Scattering of Low-Energy Electrons byTetrahydrofuran

    SciTech Connect

    Trevisan, Cynthia S.; Orel, Ann E.; Rescigno, Thomas N.

    2006-05-09

    We present the results of ab initio calculations for elasticelectron scattering by tetrahydrofuran (THF) using the complex Kohnvariational method. We carried out fixed-nuclei calculations at theequilibrium geometry of the target molecule for incident electronenergies up to 20 eV. The calculated momentum transfer cross sectionsclearly reveal the presence of broad shape resonance behavior in the 8-10eV energy range, in agreement with recent experiments. The calculateddifferential cross sections at 20 eV, which include the effects of thelong-range electron-dipole interaction, are alsofound to be in agreementwith the most recent experimental findings.

  7. Low energy elastic electron scattering from CF3Br molecules.

    PubMed

    Hargreaves, L R; Brunton, J R; Maddern, T M; Brunger, M J

    2015-03-28

    CF3Br is a potentially valuable precursor molecule for generating beams of gas phase Br radicals suitable for electron collisions studies. However, the utility of CF3Br for this purpose depends critically on the availability of sound scattering cross sections to allow the contribution of the precursor to be isolated within the total scattering signal. To this end, here we present elastic differential cross section (DCS) measurements for CF3Br at incident energies between 15 and 50 eV. Comparison of these DCSs to those from the only other available experimental study [Sunohara et al., J. Phys. B: At., Mol. Opt. Phys. 36, 1843 (2003)] and a Schwinger multichannel with pseudo potentials (SMCPPs) calculation [Bettega et al., J. Phys. B: At., Mol. Opt. Phys. 36, 1263 (2003)] shows generally a very good accord. Integral elastic and momentum transfer cross sections, derived from our DCSs, are also found to be in quite good agreement with the SMCPP results. PMID:25833582

  8. Low-energy scattering of antihydrogen by helium and molecular hydrogen

    SciTech Connect

    Armour, E. A. G.; Todd, A. C.; Liu, Y.; Gregory, M. R.; Jonsell, S.; Plummer, M.

    2008-08-08

    In this paper, we describe in detail calculations that we have carried out of cross sections for rearrangement processes in very low-energy helium+antihydrogen (H-bar) scattering that result in He{sup +}p-bar+Ps or Hep-bar+e{sup +} or {alpha}p-bar+Ps{sup -}. The interaction between the leptons is taken into account very accurately. Results are presented for all three processes. A description is also given of a preliminary calculation of elastic and antiproton annihilation cross sections for very low-energy H{sub 2}+H-bar scattering.

  9. Measurements of ultra-low-energy electron scattering cross sections of atoms and molecules

    SciTech Connect

    Kitajima, M.; Shigemura, K.; Kurokawa, M.; Odagiri, T.; Kato, H.; Hoshino, M.; Tanaka, H.; Ito, K.

    2014-03-05

    A new experimental technique for the total cross section measurements of ultra-low energy electron collisions with atoms and molecules utilizing the synchrotron radiation is presented. The technique employs a combination of the penetrating field technique and the threshold photoionization of rare gas atoms using the synchrotron radiation as an electron source in order to produce a high resolution electron beam at very low energy. Absolute total cross sections for electron scattering from He, Ne, Ar, Kr, and Xe in the energy region from extremely low electron energy to 20 eV are presented.

  10. Universality of entanglement creation in low-energy two-dimensional scattering

    SciTech Connect

    Weder, Ricardo

    2013-10-15

    We prove that the entanglement created in the low-energy scattering of two particles in two dimensions is given by a universal coefficient that is independent of the interaction potential. This is strikingly different from the three dimensional case, where it is proportional to the total scattering cross section. Before the collision the state is a product of two normalized Gaussians. We take the purity as the measure of the entanglement after the scattering. We give a rigorous computation, with error bound, of the leading order of the purity at low-energy. For a large class of potentials, that are not-necessarily spherically symmetric, we prove that the low-energy behavior of the purity, P, is universal. It is given by P=1−1/((ln(σ/ħ)){sup 2}) E, where σ is the variance of the Gaussians and the entanglement coefficient, E, depends only on the masses of the particles and not on the interaction potential. There is a strong dependence of the entanglement in the difference of the masses. The minimum is when the masses are equal, and it increases strongly with the difference of the masses. -- Highlights: •The entanglement in low-energy scattering in two dimensions is universal. It is independent of the potential. •We take the purity as the measure of entanglement. •We give a rigorous computation of the leading order of the purity at low energy. •The created entanglement depends strongly on the masses of the particles. •It takes its minimum for equal masses and it increases strongly with the difference of the masses.

  11. Low-energy theorems for nucleon-nucleon scattering at Mπ=450 MeV

    NASA Astrophysics Data System (ADS)

    Baru, V.; Epelbaum, E.; Filin, A. A.

    2016-07-01

    We apply the low-energy theorems to analyze the recent lattice QCD results for the two-nucleon system at a pion mass of Mπ≃450 MeV obtained by the NPLQCD Collaboration. We find that the binding energies of the deuteron and dineutron are inconsistent with the low-energy behavior of the corresponding phase shifts within the quoted uncertainties and vice versa. Using the binding energies of the deuteron and dineutron as input, we employ the low-energy theorems to predict the phase shifts and extract the scattering length and the effective range in the S31 and S10 channels. Our results for these quantities are consistent with those obtained by the NPLQCD Collaboration from effective field theory analyses but are in conflict with their determination based on the effective-range approximation.

  12. Two-dimensional Coulomb scattering of a quantum particle: Low-energy asymptotic behavior

    NASA Astrophysics Data System (ADS)

    Pupyshev, V. V.

    2016-07-01

    We consider a charged quantum particle moving in a two-dimensional plane in the three-dimensional coordinate space and scattering on an immovable Coulomb center in the same plane. We derive and investigate expansions of the wave function and of all radial wave functions of the particle in integer powers of the wave number and in Bessel functions of a real order. We prove that finite sums of such expansions are asymptotic in the low-energy limit.

  13. Study of Low Energy Electron Inelastic Scattering Mechanisms Using Spin Sensitive Techniques

    NASA Astrophysics Data System (ADS)

    Hsu, Hongbing

    1995-01-01

    Spin sensitive electron spectroscopies were used to study low energy electron inelastic scattering from metal surfaces and thin films. In these experiments, a beam of spin polarized electrons from a GaAs source is directed on the sample surface, and the spin polarization and intensity are measured as a function of energy loss and scattering angle by a Mott electron polarimeter coupled with a concentric hemispherical energy analyzer. Systematic studies of the angular dependence of inelastically scattered electrons were conducted on a Cu(100) surface, and Mo/Cu(100), non-magnetized Fe/Cu(100), and Co/Cu(100) films. The polarization and intensity of scattered electrons were measured as function of energy loss and scattering angle. Further studies were also conducted on Ag(100) surface and amorphous Cu/Ag(100) films. From the experimental results, the angular distributions of dipole and impact scattered electrons can be determined individually and both are found to peak in the specular scattering direction. Preliminary studies were conducted on magnetized Co/Cu(100) films. The spin dependent scattering intensity asymmetry was measured, with a clearly observable peak at energy loss of ~1 eV, which coincides with the band splitting. The polarizations of secondary electrons produced by an unpolarized primary beam were also measured. The polarizations can be related to the band polarization of magnetized cobalt films.

  14. Comprehensive study of the surface peak in charge-integrated low-energy ion scattering spectra

    SciTech Connect

    Draxler, M.; Gruber, R.; Bauer, P.; Beikler, R.; Taglauer, E.; Schmid, K.; Ermolov, S. N.

    2003-08-01

    Low-energy ion scattering is very surface sensitive if scattered ions are analyzed. By time-of-flight (TOF) techniques, the neutral and the charge-integrated spectra (ions plus neutrals) are obtained, which yield information about deeper layers. It is well known that charge integrated spectra may exhibit a surface peak which is more pronounced for heavier projectiles, e.g., Ne ions. Aiming at a more profound physical understanding of this surface peak, we performed TOF experiments and computer simulations for H, He, and Ne projectiles scattered from a polycrystalline copper target. Measurements were done in the range of 1-9 keV for a scattering angle of 129 degree sign under UHV conditions. The simulations were performed using the MARLOWE code for the given experimental parameters and a polycrystalline target. In the experiments, a pronounced surface peak was observed at low energies, which fades away at higher energies. This peak is quantitatively reproduced by the simulation. Several atomic layers may contribute to the surface peak, depending on the energy. Analyzing the contributions of the individual outermost atomic layers, one finds that the binary collisions of the projectiles with atoms in the first and the second layer yield a narrow energy distribution, while the contribution from the deeper layers is dominated by multiple scattering and therefore exhibits a very broad energy spectrum. It is shown that the appearance of a more or less pronounced surface peak is due to the relative contributions of single scattering and multiple scattering and thus depends on the projectile energy and mass.

  15. Heating due to momentum transfer in low-energy positronium-antiproton scattering

    NASA Astrophysics Data System (ADS)

    Charlton, M.; Kadyrov, A. S.; Bray, I.

    2016-09-01

    We investigate the consequences of unexpectedly large elastic cross sections for the scattering of low-energy antiprotons from n ≤3 positronium (Ps) on the experimental implementation of antihydrogen formation via Ps-antiproton collisions. The integrated elastic cross sections, obtained using the two-center convergent close-coupling theory, can be up to three orders of magnitude greater than their counterparts for antihydrogen formation. The differential momentum transfer cross sections, which suppress the large cross sections at forward scattering angles, show remarkably rich behavior across all scattering angles. We discuss the implications of these findings for the heating, via momentum transfer, of clouds of trapped antiprotons that are typically used for the creation of antihydrogen.

  16. Carrier scattering processes and low energy phonon spectroscopy in hybrid perovskites crystals

    NASA Astrophysics Data System (ADS)

    Even, Jacky; Paofai, Serge; Bourges, Philippe; Letoublon, Antoine; Cordier, Stéphane; Durand, Olivier; Katan, Claudine

    2016-03-01

    Despite the wealth of research conducted the last three years on hybrid organic perovskites (HOP), several questions remain open including: to what extend the organic moiety changes the properties of the material as compared to allinorganic (AIP) related perovskite structures. To ultimately reach an answer to this question, we have recently introduced two approaches that were designed to take the stochastic molecular degrees of freedom into account, and suggested that the high temperature cubic phase of HOP and AIP is an appropriate reference phase to rationalize HOP's properties. In this paper, we recall the main concepts and discuss more specifically the various possible couplings between charge carriers and low energy excitations such as acoustic and optical phonons. As available experimental or simulated data on low energy excitations are limited, we also present preliminary neutron scattering and ultrasonic measurements obtained and freshly prepared single crystals of CH3NH3PbBr3.

  17. A phenomenological study of photon production in low energy neutrino nucleon scattering

    SciTech Connect

    Jenkins, James P; Goldman, Terry J

    2009-01-01

    Low energy photon production is an important background to many current and future precision neutrino experiments. We present a phenomenological study of t-channel radiative corrections to neutral current neutrino nucleus scattering. After introducing the relevant processes and phenomenological coupling constants, we will explore the derived energy and angular distributions as well as total cross-section predictions along with their estimated uncertainties. This is supplemented throughout with comments on possible experimental signatures and implications. We conclude with a general discussion of the analysis in the context of complimentary methodologies. This is based on a talk presented at the DPF 2009 meeting in Detroit MI.

  18. Combining dynamic and static depth profiling in low energy ion scattering

    SciTech Connect

    Veen, Rik ter; Fartmann, Michael; Kersting, Reinhard; Hagenhoff, Birgit

    2013-01-15

    The advantages of combining dynamic and static depth profiling in low energy ion scattering are demonstrated for an Si/SiO{sub x}/W/Al{sub 2}O{sub 3} ALD stack. Dynamic depth profiling can be used to calibrate static depth profiling. Energy losses of 152 and 215 eV/nm were found for 3 keV {sup 4}He{sup +} and 5 keV {sup 4}He{sup +} primary ions, respectively, for the experimental configuration used. This is in good agreement with the values used in the field. Static depth profiling can be used to recognize sputter artifacts in dynamic depth profiles.

  19. Low-energy density of states in d-wave superconductors with extended scatterers

    NASA Astrophysics Data System (ADS)

    Adagideli, I.; Sheehy, D. E.; Goldbart, P. M.

    2002-03-01

    We investigate a novel contribution to the low-energy quasiparticle density of states (DOS) of a disordered d-wave superconductor. Related work (C. Pépin and P. A. Lee, Phys. Rev. B 63), 054502 (2001). found that the DOS is singular at zero energy, but it was later argued (A.G. Yashenkin et al., Phys. Rev. Lett. 86), 5982 (2001); A. Altland, cond-mat/0108079 (unpublished). that the results of Ref. [1] are valid only in special cases requiring fine-tuning of the parameters, and that the DOS vanishes at E=0 except in these cases. A common feature of these approaches is the assumption that the disorder potential is due to pointlike scatterers. However, previous work (I. Adagideli et al., Phys. Rev. Lett. 83) 5571 (1999). showed that the presence of extended impurities in d-wave superconductors gives rise to additional low-energy quasiparticle states. Motivated by this fact, we focus on the (previously neglected) contribution to the low-energy DOS arising from a disorder potential that consists of a random collection of extended impurities. We find that the DOS is singular at zero energy, diverging as ρ_ext(E) ~ 1/\\vert E(ln \\vert E\\vert)^3 \\vert. Our calculation neglects the role of nodal quasiparticles; indeed, we expect that they will merely furnish a subdominant additive contribution to ρ_ ext. This work was supported by D.O.E.

  20. Proton-proton, pion-proton and pion-pion diffractive collisions at ultrahigh energies

    NASA Astrophysics Data System (ADS)

    Anisovich, V. V.; Nikonov, K. V.; Nikonov, V. A.; Nyiri, J.

    2014-05-01

    The LHC energies are those at which the asymptotic regime in hadron-hadron diffractive collisions (pp, πp, ππ) might be switched on. Based on results of the Dakhno-Nikonov eikonal model which is a generalization of the Good-Walker eikonal approach for a continuous set of channels, we present a picture for transformation of the constituent quark mode to the black disk one. In the black disk mode (√ {s} >= 10 TeV), we have a growth of the logarithm squared type for total and elastic cross-sections, σtot ln2 s and σel ln2 s and (τ = q⊥2&sigma_; tot)-scaling for diffractive scattering and diffractive dissociation of hadrons. The diffractive dissociation cross-section grows as σD ln s, σDD ln s, and their relative contribution tends to zero: σD/σtot → 0, σDD/σtot → 0. Asymptotic characteristics of diffractive and total cross-sections are universal, and this results in the asymptotical equality of cross-sections for all types of hadrons (the Gribov universality). The energy scale for switching on the asymptotic mode is estimated for different processes.

  1. On the importance of full-dimensionality in low-energy molecular scattering calculations.

    PubMed

    Faure, Alexandre; Jankowski, Piotr; Stoecklin, Thierry; Szalewicz, Krzysztof

    2016-01-01

    Scattering of H2 on CO is of great importance in astrophysics and also is a benchmark system for comparing theory to experiment. We present here a new 6-dimensional potential energy surface for the ground electronic state of H2-CO with an estimated uncertainty of about 0.6 cm(-1) in the global minimum region, several times smaller than achieved earlier. This potential has been used in nearly exact 6-dimensional quantum scattering calculations to compute state-to-state cross-sections measured in low-energy crossed-beam experiments. Excellent agreement between theory and experiment has been achieved in all cases. We also show that the fully 6-dimensional approach is not needed with the current accuracy of experimental data since an equally good agreement with experiment was obtained using only a 4-dimensional treatment, which validates the rigid-rotor approach widely used in scattering calculations. This finding, which disagrees with some literature statements, is important since for larger systems full-dimensional scattering calculations are currently not possible. PMID:27333870

  2. On the importance of full-dimensionality in low-energy molecular scattering calculations

    PubMed Central

    Faure, Alexandre; Jankowski, Piotr; Stoecklin, Thierry; Szalewicz, Krzysztof

    2016-01-01

    Scattering of H2 on CO is of great importance in astrophysics and also is a benchmark system for comparing theory to experiment. We present here a new 6-dimensional potential energy surface for the ground electronic state of H2-CO with an estimated uncertainty of about 0.6 cm−1 in the global minimum region, several times smaller than achieved earlier. This potential has been used in nearly exact 6-dimensional quantum scattering calculations to compute state-to-state cross-sections measured in low-energy crossed-beam experiments. Excellent agreement between theory and experiment has been achieved in all cases. We also show that the fully 6-dimensional approach is not needed with the current accuracy of experimental data since an equally good agreement with experiment was obtained using only a 4-dimensional treatment, which validates the rigid-rotor approach widely used in scattering calculations. This finding, which disagrees with some literature statements, is important since for larger systems full-dimensional scattering calculations are currently not possible. PMID:27333870

  3. Virtual Compton Scattering at low energy and the generalized polarizabilities of the nucleon

    SciTech Connect

    Helene Fonvieille

    2003-05-01

    Virtual Compton Scattering (VCS) {gamma}*p {yields} {gamma}p at low CM energy gives access to the Generalized Polarizabilities of the nucleon. These observables generalize the concept of electromagnetic polarizabilities to the case of a virtual photon. Dedicated VCS experiments have been performed at MAMI, Jefferson Lab and MIT-Bates. The experimental status is reviewed, including analysis methods and physics results. The measurement of absolute (ep {yields} ep{gamma}) cross sections allows the extraction of the two unpolarized VCS structure functions P{sub LL}-P{sub TT}/{epsilon} and P{sub LT}, which are combinations of the Generalized Polarizabilities of the proton. Future prospects in the field of VCS at low energy are also presented.

  4. Low-energy extensions of the eikonal approximation to heavy-ion scattering

    SciTech Connect

    Aguiar, C.E.; Aguiar, C.E.; Zardi, F.; Vitturi, A.

    1997-09-01

    We discuss different schemes devised to extend the eikonal approximation to the regime of low bombarding energies (below 50 MeV per nucleon) in heavy-ion collisions. From one side we consider the first- and second-order corrections derived from Wallace{close_quote}s expansion. As an alternative approach we examine the procedure of accounting for the distortion of the eikonal straight-line trajectory by shifting the impact parameter to the corresponding classical turning point. The two methods are tested for different combinations of colliding systems and bombarding energies, by comparing the angular distributions they provide with the exact solution of the scattering problem. We find that the best results are obtained with the shifted trajectories, the Wallace expansion showing a slow convergence at low energies, in particular for heavy systems characterized by a strong Coulomb field. {copyright} {ital 1997} {ital The American Physical Society}

  5. Surface structure and composition determination by low-energy electron scattering and Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Sun, Jiebing

    This thesis reports on surface and surface alloy structural and compositional determination with low-energy electron scattering and Monte Carlo simulations. Low-energy electron diffraction (LEED) technique and the newly developed low-energy electron microscopy (LEEM) IV technique are used to measure the electron scattering intensity spectra and dynamical multiple scattering analysis is performed to optimize the surface structural and non-structural parameters via comparison between the experimental spectra and calculated ones. My work focuses on the following four surface systems. (111), (110) and (001) surface structures of the semimetal bismuth are determined with LEED. The unreconstructed (1x1) structure is revealed for all three surfaces. The interlayer spacings for several outermost layers are resolved. All results agree with those obtained by first-principles calculations. The Debye temperatures for the Bi(111) and Bi(110) surface are found to be lower than that of the Bi bulk. In conjunction with the LEED technique, scanning tunneling microscopy (STM) observation is performed on the Bi(001) surface. Surface topology images show dominant bilayer steps and no single layer step. The newly developed LEEM-IV technique is used to investigate the PdCu surface alloy on the substrate Cu(001). Studies include quantifying the temporal evolution of Pd concentration on the Cu(001) terrace, mapping the 3D heterogeneous surface chemical composition, and identifying a step-overgrowth thin film growth mechanism. It is found that, at the initial deposition stages, Pd atoms reside in the second layer at the sample temperature of 473 K, and the Pd concentration increases exponentially with time. The heterogeneous structure and composition near the steps are found to be a result of the step-overgrowth. We highlight the LEEM-IV technique which provides a high lateral resolution at surfaces. We demonstrate a 3D profile of Pd concentration in the surface region by using the LEEM

  6. Low-energy positron scattering from DNA nucleobases: the effects from permanent dipoles

    NASA Astrophysics Data System (ADS)

    Franz, Jan; Gianturco, Francesco Antonio

    2014-10-01

    Ab initio quantum calculations for low-energy positron scattering from gas-phase isolated molecular nucleobases which are part of the DNA structure are presented and discussed over the range of 1 eV to 25 eV. The calculations report the integral cross sections (ICSs) and the momentum-transfer cross sections (MTCSs) for Adenine, Guanine, Thymine and Cytosine. The calculations show very clearly the important role of the dominant long-range interaction between the positron projectile and the permanent dipole-moments of the target molecules in deciding the relative sizes of the ICSs and MTCSs for the present series of molecules. Such results confirm the largely repulsive interaction between positron and DNA bases, which is nevertheless producing very large cross sections and marked deflection functions from the latter molecules. Contribution to the Topical Issue "Nano-scale Insights into Ion-beam Cancer Therapy", edited by Andrey V. Solov'yov, Nigel Mason, Paulo Limão-Vieira and Malgorzata Smialek-Telega.

  7. Surface analysis of zeolites: An XPS, variable kinetic energy XPS, and low energy ion scattering study

    NASA Astrophysics Data System (ADS)

    Bare, Simon R.; Knop-Gericke, Axel; Teschner, Detre; Hävacker, Michael; Blume, Raoul; Rocha, Tulio; Schlögl, Robert; Chan, Ally S. Y.; Blackwell, N.; Charochak, M. E.; ter Veen, Rik; Brongersma, Hidde H.

    2016-06-01

    The surface Si/Al ratio in a series of zeolite Y samples has been obtained using laboratory XPS, synchrotron (variable kinetic energy) XPS, and low energy ion scattering (LEIS) spectroscopy. The non-destructive depth profile obtained using variable kinetic energy XPS is compared to that from the destructive argon ion bombardment depth profile from the lab XPS instrument. All of the data indicate that the near surface region of both the ammonium form and steamed Y zeolites is strongly enriched in aluminum. It is shown that when the inelastic mean free path of the photoelectrons is taken into account the laboratory XPS of aluminosilicates zeolites does not provide a true measurement of the surface stoichiometry, while variable kinetic energy XPS results in a more surface sensitive measurement. A comprehensive Si/Al concentration profile as a function of depth is developed by combining the data from the three surface characterization techniques. The LEIS spectroscopy reveals that the topmost atomic layer is further enriched in Al compared to subsequent layers.

  8. Low energy scattering cross section ratios of 14N(p ,p ) 14N

    NASA Astrophysics Data System (ADS)

    deBoer, R. J.; Bardayan, D. W.; Görres, J.; LeBlanc, P. J.; Manukyan, K. V.; Moran, M. T.; Smith, K.; Tan, W.; Uberseder, E.; Wiescher, M.; Bertone, P. F.; Champagne, A. E.; Islam, M. S.

    2015-04-01

    Background: The slowest reaction in the first CNO cycle is 14N(p ,γ ) 15O , therefore its rate determines the overall energy production efficiency of the entire cycle. The cross section presents several strong resonance contributions, especially for the ground-state transition. Some of the properties of the corresponding levels in the 15O compound nucleus remain uncertain, which affects the uncertainty in extrapolating the capture cross section to the low energy range of astrophysical interest. Purpose: The 14N(p ,γ ) 15O cross section can be described by using the phenomenological R matrix. Over the energy range of interest, only the proton and γ -ray channels are open. Since resonance capture makes significant contributions to the 14N(p ,γ ) 15O cross section, resonant proton scattering data can be used to provide additional constraints on the R -matrix fit of the capture data. Methods: A 4 MV KN Van de Graaff accelerator was used to bombard protons onto a windowless gas target containing enriched 14N gas over the proton energy range from Ep=1.0 to 3.0 MeV. Scattered protons were detected at θlab=90 , 120∘, 135∘, 150∘, and 160∘ using ruggedized silicon detectors. In addition, a 10 MV FN Tandem Van de Graaff accelerator was used to accelerate protons onto a solid Adenine (C5H5N5 ) target, of natural isotopic abundance, evaporated onto a thin self-supporting carbon backing, over the energy range from Ep=1.8 to 4.0 MeV. Scattered protons were detected at 28 angles between θlab=30 .4∘ and 167 .7∘ by using silicon photodiode detectors. Results: Relative cross sections were extracted from both measurements. While the relative cross sections do not provide as much constraint as absolute measurements, they greatly reduce the dependence of the data on otherwise significant systematic uncertainties, which are more difficult to quantify. The data are fit simultaneously using an R -matrix analysis and level energies and proton widths are extracted. Even

  9. Neutron inelastic scattering measurements of low-energy phonons in the multiferroic BiFeO3

    SciTech Connect

    Schneeloch, John A.; Xu, Zhijun; Wen, Jinsheng; Gehring, P. M.; Stock, C.; Matsuda, Masaaki; Winn, Barry L.; Gu, Genda; Shapiro, Stephen M.; Birgeneau, R. J.; Ushiyama, T.; Yanagisawa, Y.; Tomioka, Y.; Ito, T.; Xu, Guangyong

    2015-02-10

    In this study, we present neutron inelastic scattering measurements of the low-energy phonons in single crystal BiFeO3. The dispersions of the three acoustic phonon modes (LA along [100], TA1 along [010], and TA2 along [110]) and two low-energy optic phonon modes (LO and TO1) have been mapped out between 300 and 700 K. Elastic constants are extracted from the phonon measurements. The energy linewidths of both TA phonons at the zone boundary clearly broaden when the system is warmed toward the magnetic ordering temperature TN=640 K. In conclusion, this suggests that the magnetic order and low-energy lattice dynamics in this multiferroic material are coupled.

  10. Neutron inelastic scattering measurements of low-energy phonons in the multiferroic BiFeO3

    DOE PAGES

    Schneeloch, John A.; Xu, Zhijun; Wen, Jinsheng; Gehring, P. M.; Stock, C.; Matsuda, Masaaki; Winn, Barry L.; Gu, Genda; Shapiro, Stephen M.; Birgeneau, R. J.; et al

    2015-02-10

    In this study, we present neutron inelastic scattering measurements of the low-energy phonons in single crystal BiFeO3. The dispersions of the three acoustic phonon modes (LA along [100], TA1 along [010], and TA2 along [110]) and two low-energy optic phonon modes (LO and TO1) have been mapped out between 300 and 700 K. Elastic constants are extracted from the phonon measurements. The energy linewidths of both TA phonons at the zone boundary clearly broaden when the system is warmed toward the magnetic ordering temperature TN=640 K. In conclusion, this suggests that the magnetic order and low-energy lattice dynamics in thismore » multiferroic material are coupled.« less

  11. Low energy excitations in iridates studied with Resonant Inelastic X-ray Scattering

    NASA Astrophysics Data System (ADS)

    Liu, Xuerong

    2013-03-01

    In the iridium oxides, the strong spin-orbit coupling (SOC) of the 5d iridium electrons entangles the orbital and spin degrees of freedom, providing opportunities for exotic magnetic states with highly anisotropic exchange interactions. At the same time, the spatially extended 5d electrons are expected to have much stronger hybridization with the oxygen 2p orbitals, comparing with that in 3d transition element compounds. Both factors make crystal symmetry and local environment crucial in determining the electronic and magnetic properties of the iridates. We present here our resonant inelastic X-ray scattering (RIXS) studies of a number of octahedrally coordinated iridates with special structures, exploring these effects. In particular, for the 1-D spin 1/2 chain compound, Sr3CuIrO6, the wavefunction of the hole in the t2g manifold was reconstructed based on the RIXS spectra. Our results show that it is significantly modified from the isotropic shape expected for Jeff = 1 / 2 states in the strong SOC limit, due to the distortion of the oxygen octahedral cage. This distortion is comparable to, or smaller than, that present in most iridates and thus this work emphasizes the importance of local symmetry for the iridate families. Further, the magnetic excitations of this material were also measured. A large gap of ~30 meV, was found, comparable to the magnetic dispersion bandwidth. This is in contrast to the gapless dispersion expected for linear chain with isotropic Heisenberg exchange interaction. We also studied Na4Ir3O8 which has a hyperkagome lattice, and is a candidate quantum spin liquid. Here, a low energy continuum is observed below the d-d excitations. Optical conductivity measurements performed on the same sample and polarization dependence of the RIXS signal suggest that these excitations are magnetic in origin, agreeing with the spin-liquid state prediction. The work at Brookhaven was supported by the U.S. Department of Energy, Division of Materials Science

  12. Improved description of the πN-scattering phenomenology at low energies in covariant baryon chiral perturbation theory

    SciTech Connect

    Alarcón, J.M.; Martin Camalich, J.; Oller, J.A.

    2013-09-15

    We present a novel analysis of the πN scattering amplitude in covariant baryon chiral perturbation theory up to O(p{sup 3}) within the extended-on-mass-shell renormalization scheme and including the Δ(1232) explicitly in the δ-counting. We take the hadronic phase shifts provided by partial wave analyses as basic experimental information to fix the low-energy constants. Subsequently, we study in detail the various observables and low-energy theorems related to the πN scattering amplitude. In particular, we discuss the results and chiral expansion of the phase shifts, the threshold coefficients, the Goldberger–Treiman relation, the pion–nucleon sigma term and the extrapolation onto the subthreshold region. The chiral representation of the amplitude in the theory with the Δ presents a good convergence from very low energies in the subthreshold region up to energies above threshold and below the Δ(1232) peak, leading also to a phenomenological description perfectly consistent with the one reported by the respective partial wave analyses and independent determinations. We conclude that a model-independent and systematic framework to analyze πN-scattering observables using directly experimental data shall be possible in covariant baryon chiral perturbation theory. -- Highlights: •The chiral series shows a better convergence than previous analyses. •Improved prediction of the πN scattering phenomenology. •This analysis connects reliably the subthreshold and physical regions for the first time using ChPT. •Extraction of an accurate value of σ{sub πN} from experimental data. •σ{sub πN} extracted is compatible with related phenomenology.

  13. Low-Energy Parameters of the Nucleon-Nucleon Scattering and Deuteron Properties, Electromagnetic Interactions with Bound Systems

    NASA Astrophysics Data System (ADS)

    Shebeko, A.; Dubovik, E.

    2013-08-01

    One more application of the method of unitary clothing transformations (UCT's) in the theory of nucleon-nucleon ( N - N) interaction has been presented. We have extended our previous analysis (Dubovik and Shebeko in Few-Body Syst 48:109-142, 2010) of the N - N scattering below the pion production threshold to treat the neutron-proton ( n - p) scattering at low energies and the deuteron static properties. Our calculations of deuteron magnetic and quadrupole moments have been carried out in the framework of a gauge independent description of electromagnetic (EM) interactions with nuclei (bound systems) using the clothed particle representation of the Hamiltonian, the boost and EM current density operators for the n-p system.

  14. Importance of resonance widths in low-energy scattering of weakly bound light-mass nuclei

    NASA Astrophysics Data System (ADS)

    Fraser, P. R.; Massen-Hane, K.; Amos, K.; Bray, I.; Canton, L.; Fossión, R.; Kadyrov, A. S.; Karataglidis, S.; Svenne, J. P.; van der Knijff, D.

    2016-09-01

    What effect do particle-emitting resonances have on the scattering cross section? What physical considerations are necessary when modeling these resonances? These questions are important when theoretically describing scattering experiments with radioactive ion beams which investigate the frontiers of the table of nuclides, far from stability. Herein, a novel method is developed that describes resonant nuclear scattering from which centroids and widths in the compound nucleus are obtained when one of the interacting bodies has particle unstable resonances. The method gives cross sections without unphysical behavior that is found if simple Lorentzian forms are used to describe resonant target states. The resultant cross sections differ significantly from those obtained when the states in the coupled channel calculations are taken to have zero width, and compound-system resonances are better matched to observed values.

  15. Oscillatory spin asymmetric scattering of low-energy He+ ions on Sn surfaces

    NASA Astrophysics Data System (ADS)

    Suzuki, T. T.; Sakai, O.

    2016-09-01

    Spin-polarized He+ ion scattering spectroscopy (SP-ISS) study on a polycrystalline Sn target surface is reported. We observed substantial spin dependent He+ ion scattering on the non-magnetic Sn target. It is not due to He+ ion neutralization, but it is attributed to spin-orbit coupling (SOC) that acts transiently on the He+ 1 s electron spin in the He+-Sn atom binary collision. We found that the spin dependent scattering quantified as the spin asymmetry exhibits periodic oscillation with the reciprocal of the He+ ion velocity. The oscillation originates from the SOC induced-slight energy difference of the [He+-Sn] and [He0-Sn+] systems which are involved in the quasi-resonant charge transfer. The oscillatory spin asymmetry shows that SOC arises from collision induced intermediate state.

  16. Elastic scattering of low energy electrons in partially ionized dense semiclassical plasma

    SciTech Connect

    Dzhumagulova, K. N. Shalenov, E. O.; Ramazanov, T. S.

    2015-08-15

    Elastic scattering of electrons by hydrogen atoms in a dense semiclassical hydrogen plasma for low impact energies has been studied. Differential scattering cross sections were calculated within the effective model of electron-atom interaction taking into account the effect of screening as well as the quantum mechanical effect of diffraction. The calculations were carried out on the basis of the phase-function method. The influence of the diffraction effect on the Ramsauer–Townsend effect was studied on the basis of a comparison with results made within the effective polarization model of the Buckingham type.

  17. Very low-energy total cross sections and the experimental scattering length for the positron-xenon system

    NASA Astrophysics Data System (ADS)

    Zecca, Antonio; Chiari, Luca; Trainotti, Emanuele; Brunger, Michael J.

    2012-04-01

    We report total cross-section (TCS) results for low-energy positron scattering from the noble gas xenon. A comparison with previous measurements shows a good level of accord with the recent results of the ANU group (2011 New J. Phys. 13 125004). Very good qualitative agreement is also found with the convergent close-coupling (CCC) calculation of Fursa and Bray (2012 New J. Phys. 14 035002) over most of the common energies. By using the shape of the CCC results as a guide, we also extrapolate our measured cross sections to very low energy. With the aid of the CCC theory, we therefore derive the first experimental estimate for the positron-xenon scattering length of a = -99.2 ± 18.4 au. This value is found to be consistent with the CCC-based estimate and also with those of some other theories. This result supports the existence of a positron-xenon virtual state at a positron energy ɛ = (1.4 ± 0.6) × 10-3 eV.

  18. Refutation of a propensity rule in low-energy electron scattering by neon atoms

    NASA Astrophysics Data System (ADS)

    Hargreaves, Leigh; Campbell, Colin; Khakoo, Murtadha A.; Zatsarinny, Oleg; Bartschat, Klaus

    2012-06-01

    Since the work of Kohmoto and Fano [1] there has been considerable interest in the sign of the `orientation' parameter Lperp, which describes the angular momentum of an excited electronic state perpendicular to the scattering plane imparted by the projectile electron. In a polarization-correlation experiment, Lperp can be related to the measurable Stokes parameter P3 (Lperp = -P3), which describes the circular polarization of the photon emitted perpendicular to the scattering plane. Of particular interest is the empirical observation that, for S to P transitions, P3 universally trends to negative values for small scattering angles, regardless of the target or incident energy. A number of studies (e.g. [1-3]) have therefore considered the generality of this `propensity rule' and its theoretical basis. Here, a recent joint experimental and theoretical study of electronic excitation of the resonant transition in neon by 25eV electrons is presented. In both the theoretical and experimental data it is observed that P3 is positive at small scattering angles, demonstrating a refutation of this propensity rule, in disagreement with the classical arguments of Kohomoto and Fano [1]. [4pt] [1] M. Kohmoto and U. Fano, J. Phys. B 14, L447 (1981)[0pt] [2] D. H. Madison and K. H. Winters, Phys. Rev. Lett. 47, 1885 (1981)[0pt] [3] K. Bartschat, N. Andersen and D. Loveall, Phys. Rev. Lett. 83, 5254 (1999)

  19. Single-collision approximation for p{sup 3}-He elastic scattering at low energy

    SciTech Connect

    Abusini, M.

    2009-06-15

    A theoretical approach to studying four-body reactions of p{sup 3}-He elastic scattering that takes consistently into account the single-collision mechanism is reported. The theoretical results obtained by this method were compared with experimental data, and the agreement is found to be quite satisfactory.

  20. Features of spectra of low-energy neon ions scattered from gallium phosphide

    NASA Astrophysics Data System (ADS)

    Tolstoguzov, A. B.; Belykh, S. F.; Gololobov, G. P.; Suvorov, D. V.

    2016-09-01

    Using mass-resolved ion scattering spectrometry, spectra of Ne+ ions scattered at an angle of 120° from the surface of GaP in the energy range of 0.4-1.96 keV have been studied in detail. In the spectra, in addition to the peaks of elastic binary Ne+/P and Ne+/Ga collisions, the peak of sputtered neon ions has been found, as well as the wide peak (a "hump"), the energy of which slightly depends on the energy of primary ions and the intensity considerably increases with an increase in this energy. In our opinion, the main contribution to this peak is made by neon ions that undergo multiple collisions with gallium and phosphorus atoms on the surface and deeper layers of the sample and keep their charge due to reionization processes.

  1. Charge exchange processes in He+/Cu scattering at low energy

    NASA Astrophysics Data System (ADS)

    Khalal-Kouache, K.; Bruckner, B.; Roth, D.; Goebl, D.; Bauer, P.

    2016-09-01

    In this paper we present results on charge exchange of He+ ions at a polycrystalline Cu surface. Monte Carlo simulations were used to calculate the trajectories of projectiles scattered by an angle Θ = 136 ° . By including Auger neutralization and charge exchange in close collisions, energy spectra of the scattered ions as well as ion fraction values were calculated for primary energies in the range 0.5-5 keV and compared to experimental results. In the simulations, the Auger neutralization rate Γ and the probabilities of resonant neutralization (PRN) and reionization (PRI) are treated as free parameters. Using well accepted values from literature for these quantities very good agreement between simulations and experimental data was achieved.

  2. Modelization For Electromagnetic Electron Scattering at Low Energies for Radiotherapy applications.

    NASA Astrophysics Data System (ADS)

    Nazaryan, Vahagn; Gueye, Paul

    2006-03-01

    Since release of the GEANT4 particle simulation toolkit in 2003, there has been a growing interest in its applications to medical physics. The applicability of GEANT4 to radiotherapy has been a subject of several investigations in recent years, and it was found to be of great use. Its low-energy model allows for electromagnetic interaction simulations down to 250 eV. The electron physics data are obtained from the Lawrence Livermore National Laboratory's Evaluated Electron Data Library (EEDL). At very lower energies (below 10 MeV), some of the tabulated data in EEDL have big uncertainties (more than 50%), and rely on various extrapolations to energy regions where there is no experimental data. We have investigated the variations of these cross-section data to radiotherapy applications. Our study suggests a strong need for better theoretical models of electron interactions with matter at these energies, and the necessity of new and more reliable experimental data. The progress towards such theoretical model will be presented.

  3. H-He elastic scattering at low energies: Contribution of nonzero partial waves

    SciTech Connect

    Sinha, Prabal K.; Ghosh, A.S.

    2005-01-01

    The present study reports the nonzero partial wave elastic cross sections together with s-wave results for the scattering of an antihydrogen atom off a gaseous helium target at thermal energies (up to 10{sup -2} a.u.). We have used a nonadiabatic atomic orbital method having different basis sets to investigate the system. The consideration of all the significant partial waves (up to J=24) reduces the oscillatory nature present in the individual partial wave cross section. The added elastic cross section is almost constant up to 10{sup -7} a.u. and then decreases steadily and very slowly with increasing energy.

  4. QED radiative corrections to low-energy Møller and Bhabha scattering

    NASA Astrophysics Data System (ADS)

    Epstein, Charles S.; Milner, Richard G.

    2016-08-01

    We present a treatment of the next-to-leading-order radiative corrections to unpolarized Møller and Bhabha scattering without resorting to ultrarelativistic approximations. We extend existing soft-photon radiative corrections with new hard-photon bremsstrahlung calculations so that the effect of photon emission is taken into account for any photon energy. This formulation is intended for application in the OLYMPUS experiment and the upcoming DarkLight experiment but is applicable to a broad range of experiments at energies where QED is a sufficient description.

  5. Low energy elastic electron scattering from CF{sub 3}Br molecules

    SciTech Connect

    Hargreaves, L. R.; Brunton, J. R.; Maddern, T. M.; Brunger, M. J.

    2015-03-28

    CF{sub 3}Br is a potentially valuable precursor molecule for generating beams of gas phase Br radicals suitable for electron collisions studies. However, the utility of CF{sub 3}Br for this purpose depends critically on the availability of sound scattering cross sections to allow the contribution of the precursor to be isolated within the total scattering signal. To this end, here we present elastic differential cross section (DCS) measurements for CF{sub 3}Br at incident energies between 15 and 50 eV. Comparison of these DCSs to those from the only other available experimental study [Sunohara et al., J. Phys. B: At., Mol. Opt. Phys. 36, 1843 (2003)] and a Schwinger multichannel with pseudo potentials (SMCPPs) calculation [Bettega et al., J. Phys. B: At., Mol. Opt. Phys. 36, 1263 (2003)] shows generally a very good accord. Integral elastic and momentum transfer cross sections, derived from our DCSs, are also found to be in quite good agreement with the SMCPP results.

  6. Low energy scatter due to in-situ irradiation of solid tumors in laboratory rats

    SciTech Connect

    Ritenour, E.R. Jr.

    1980-01-01

    A study of the pattern of scattered radiation in laboratory rat cadavers during irradiation of solid tumors on the animals' flanks was performed. The animals were wrapped in a lead shield having a circular cutout through which the tumor protruded. Irradiations were performed with a 250 kVp 15ma X-ray machine with a measured half value layer of 1.39 mmCu. Lead shielding was of sufficient thickness to attenuate essentially all of the beam. The absorbed dose measured in the animal was then due to internal scatter from the tumor. Arrays of thermoluminescent dosimeters (TLDs) were placed beneath the skin of 17 animals bearing a solid tumor (hepatoma H-4-II-E). Absorbed dose was seen to vary isotropically, decreasing as the inverse distance squared from the tumor. Analysis of experimental error played a major role in this study. A pilot study resulted in standard errors that were 35% of the mean absorbed dose measurements. A careful reassessment of methods of manipulating the animals and the dosimetry system resulted in a reduction in standard error to 14% of the mean for small groups (less than 10 animals).

  7. Elastic alpha scattering experiments and the alpha-nucleus optical potential at low energies

    SciTech Connect

    Mohr, P.; Kiss, G.G.; Fülöp, Zs.; Galaviz, D.; Gyürky, Gy.; Somorjai, E.

    2013-11-15

    High precision angular distribution data of (α,α) elastic scattering are presented for the nuclei {sup 89}Y, {sup 92}Mo, {sup 106,110,116}Cd, {sup 112,124}Sn, and {sup 144}Sm at energies around the Coulomb barrier. Such data with small experimental uncertainties over the full angular range (20–170°) are the indispensable prerequisite for the extraction of local optical potentials and for the determination of the total reaction cross section σ{sub reac}. A systematic fitting procedure was applied to the experimental scattering data presented to obtain comprehensive local potential parameter sets that are composed of a real folding potential and an imaginary potential of Woods–Saxon surface type. The potential parameters obtained were used in turn to construct a new systematic α-nucleus potential with very few parameters. Although this new potential cannot reproduce the angular distributions with the same small deviations as the local potential, the new potential is able to predict the total reaction cross sections for all cases under study.

  8. Experimental study of {sup 6}He+{sup 9}Be elastic scattering at low energies

    SciTech Connect

    Pires, K. C. C.; Lichtenthaeler, R.; Lepine-Szily, A.; Guimaraes, V.; Faria, P. N. de; Barioni, A.; Mendes Junior, D. R.; Morcelle, V.; Pampa Condori, R.; Morais, M. C.; Zamora, J. C.; Crema, E.; Moro, A. M.; Rodriguez-Gallardo, M.; Assuncao, M.; Shorto, J. M. B.; Mukherjee, S.

    2011-06-15

    New data for the {sup 6}He+{sup 9}Be reaction at E{sub lab}=16.2 and 21.3 MeV have been taken and analyzed. The effect of the collective couplings to the excited states of the target has been studied by means of coupled-channels calculations, using a double-folding potential for the bare interaction between the colliding nuclei, supplemented with a phenomenological imaginary part of Woods-Saxon type. In addition, three- and four-body continuum-discretized coupled-channels calculations have been performed to investigate the effect of the projectile breakup on the elastic scattering. Both effects, the coupling to target and projectile excited states, are found to affect significantly the elastic scattering. The trivial local polarization potential extracted from the continuum-discretized coupled-channels calculations indicates that continuum couplings produce a repulsive real part and a long-range imaginary part in the projectile-target interaction.

  9. Low-energy electron elastic scattering cross sections for excited Au and Pt atoms

    NASA Astrophysics Data System (ADS)

    Felfli, Zineb; Eure, Amanda R.; Msezane, Alfred Z.; Sokolovski, Dmitri

    2010-05-01

    Electron elastic total cross sections (TCSs) and differential cross sections (DCSs) in both impact energy and scattering angle for the excited Au and Pt atoms are calculated in the electron impact energy range 0 ⩽ E ⩽ 4.0 eV. The cross sections are found to be characterized by very sharp long-lived resonances whose positions are identified with the binding energies of the excited anions formed during the collisions. The recent novel Regge-pole methodology wherein is embedded through the Mulholland formula the electron-electron correlations is used together with a Thomas-Fermi type potential incorporating the crucial core-polarization interaction for the calculations of the TCSs. The DCSs are evaluated using a partial wave expansion. The Ramsauer-Townsend minima, the shape resonances and the binding energies of the excited Au - and Pt - anions are extracted from the cross sections, while the critical minima are determined from the DCSs.

  10. Low-energy photodetachment of Ga- and elastic electron scattering from neutral Ga

    NASA Astrophysics Data System (ADS)

    Wang, Kedong; Zatsarinny, Oleg; Bartschat, Klaus

    2016-08-01

    We present a comprehensive study of the photodetachment of the negative gallium ion and elastic electron scattering from neutral Ga for photon and electron energies ranging from threshold to 12 eV. The calculations are carried out with the B -spline R -matrix method. A multiconfiguration Hartree-Fock method with nonorthogonal term-dependent orbitals is employed to generate accurate initial- and final-state wave functions. The close-coupling expansions include the 4 s 24 p n l (k l ) bound and continuum states of Ga and the 4 s -excited autoionizing states 4 s 4 p2 . The calculated photodetachment and elastic cross sections exhibit prominent resonance features. In order to clarify the origin of these resonances, the contributions of the major ionization channels to the partial cross sections are analyzed in detail.

  11. Curve crossing for low-energy elastic scattering of He/+/ by Ne.

    NASA Technical Reports Server (NTRS)

    Bobbio, S. M.; Doverspike, L. D.; Champion, R. L.

    1973-01-01

    The perturbation seen in the experimental differential elastic-scattering cross section for the 40-eV He/+/ + Ne system has been attributed to a single crossing of two intermolecular potential-energy curves. A new theoretical treatment of the curve-crossing problem, namely, that of Delos and Thorson, is employed to obtain the crossing probabilities and phases associated with the crossing. These are determined by utilizing ab initio potentials involved in the crossing and are further used in a partial-wave calculation of the cross section, which is compared with our experiment. The origin of the oscillatory structure observed in the differential cross section is discussed in semiclassical terms by defining the problem in terms of two pseudo-deflection-functions. A rainbow effect is shown to be related to a particular feature (a maximum rather than a minimum) of these deflection functions.

  12. Higher lying resonances in low-energy electron scattering with carbon monoxide*

    NASA Astrophysics Data System (ADS)

    Dora, Amar; Tennyson, Jonathan; Chakrabarti, Kalyan

    2016-10-01

    R-matrix calculations on electron collisions with CO are reported whose aim is to identify any higher-lying resonances above the well-reported and lowest 2Π resonance at about 1.6 eV. Extensive tests with respect to basis sets, target models and scattering models are performed. The final results are reported for the larger cc-pVTZ basis set using a 50 state close-coupling (CC) calculation. The Breit-Wigner eigenphase sum and the time-delay methods are used to detect and fit any resonances. Both these methods find a very narrow 2Σ+ symmetry Feshbach-type resonance very close to the target excitation threshold of the b 3Σ+ state which lies at 12.9 eV in the calculations. This resonance is seen in the CC calculation using cc-pVTZ basis set while a CC calculation using the cc-pVDZ basis set does not produce this feature. The electronic structure of CO- is analysed in the asymptotic region; 45 molecular states are found to correlate with states dissociating to an anion and an atom. Electronic structure calculations are used to study the behaviour of these states at large internuclear separation. Quantitative results for the total, elastic and electronic excitation cross sections are also presented. The significance of these results for models of the observed dissociative electron attachment of CO in the 10 eV region is discussed. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limão-Vieira, Gustavo García, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrović.

  13. Multiple scattering of low energy H+ ions in matter: Approximation of mean energy on the Sigmund and Winterbon model

    NASA Astrophysics Data System (ADS)

    Mekhtiche, A.; Khalal-Kouache, K.

    2016-09-01

    In this paper, angular distributions of slow H+ ions transmitted through different targets (Al, Ag and Au) are calculated using the model of Sigmund and Winterbon (SW) in the multiple scattering theory. Valdés and Arista (VA) developed a method extending the SW model by including the effect of energy loss in the calculation of angular distributions of transmitted ions. Another method has been proposed for such calculations: one can consider the SW model by using an average value for the energy of the ions inside the target. In this contribution, a new expression is proposed for the mean energy which gives a better agreement with the VA model than the precedent one at low energy. Different potentials have been considered to describe the interaction projectile-target atom in this study and the new expression is found to be independent of the interaction potential.

  14. Measurement of the beam-recoil polarization in low-energy virtual Compton scattering from the proton

    NASA Astrophysics Data System (ADS)

    Doria, L.; Janssens, P.; Achenbach, P.; Ayerbe Gayoso, C.; Baumann, D.; Bensafa, I.; Benali, M.; Beričič, J.; Bernauer, J. C.; Böhm, R.; Bosnar, D.; Correa, L.; D'Hose, N.; Defaÿ, X.; Ding, M.; Distler, M. O.; Fonvieille, H.; Friedrich, J.; Friedrich, J. M.; Laveissière, G.; Makek, M.; Marroncle, J.; Merkel, H.; Mihovilovič, M.; Müller, U.; Nungesser, L.; Pasquini, B.; Pochodzalla, J.; Postavaru, O.; Potokar, M.; Ryckbosch, D.; Sánchez Majos, S.; Schlimme, B. S.; Seimetz, M.; Širca, S.; Tamas, G.; Van de Vyver, R.; Van Hoorebeke, L.; Van Overloop, A.; Walcher, Th.; Weinriefer, M.; A1 Collaboration

    2015-11-01

    Double-polarization observables in the reaction e ⃗p →e'p ⃗'γ have been measured at Q2=0.33 (GeV/c ) 2 . The experiment was performed at the spectrometer setup of the A1 Collaboration using the 855 MeV polarized electron beam provided by the Mainz Microtron (MAMI) and a recoil proton polarimeter. From the double-polarization observables the structure function PLT ⊥ is extracted for the first time, with the value (-15.4 ±3 .3(stat .)-2.4+1.5(syst.)) GeV-2 , using the low-energy theorem for virtual Compton scattering. This structure function provides a hitherto unmeasured linear combination of the generalized polarizabilities of the proton.

  15. Real-space multiple scattering theory calculations of LEED (low-energy electron diffraction) intensities for stepped surfaces

    SciTech Connect

    Zhang, X.-G.; Rous, P.J.; Van Hove, M.A. ); MacLaren, J.M. ); Gonis, A. ); Somorjai, G.A. California Univ., Berkeley, CA . Dept. of Chemistry)

    1990-07-25

    We use a newly developed real-space multiple scattering theory (RS-MST) to calculate low-energy electron diffraction (LEED) intensities from stepped surfaces. In this calculation the electron wavefunctions are expanded in terms of an angular momentum basis, utilizing the property of removal invariance of systems with semi-infinite periodicity. This strongly reduces the dependence of the calculation on the interlayer spacing and thus opens up the possibility of treating more open surfaces. This includes in particular stepped surfaces, to which conventional methods cannot be applied. Applications of the formalism to various stepped surfaces are presented. In particular, the results for Cu(311) and (331) surfaces obtained from both the layer doubling and RS-MST methods are compared. In addition, numerical techniques which can improve the convergence as well as the speed of the RS-MST approach are discussed. 6 refs., 3 figs.

  16. A computational analysis of low-energy electron scattering from gaseous cyclopropane

    NASA Astrophysics Data System (ADS)

    Curík, R.; Gianturco, F. A.

    2002-02-01

    Absolute elastic cross sections, integral and differential, are computed for electron-cyclopropane collisions at energies from 1.0 up to 15.0 eV, spanning the region where possible shape resonance structures were detected by earlier experiments and calculations. The present results confirm the above findings and locate a resonance of A2' symmetry around 6.0 eV and a broader, weaker resonance of A2'' symmetry around 8 eV. The calculations are further shown to be in good agreement with the existing measurements of the angular distributions of the scattered electrons at energies from 2.0 up to 10.0 eV. The presently computed cross sections also agree with earlier R-matrix calculations (Beyer T, Nestmann B M, Sarpal B K and Peyerimhoff S D 1997 J. Phys. B: At. Mol. Opt. Phys. 30 3431) and with the available integral cross section measurements. A model local exchange potential of very simple usage is shown to provide quite good accord with the exact calculations at the static-exchange level.

  17. Low-energy electron elastic scattering from Os atom: New electron affinity

    NASA Astrophysics Data System (ADS)

    Felfli, Z.; Kiros, F.; Msezane, A. Z.

    2013-05-01

    Bilodeau and Haugan measured the binding energies (BEs) of the ground state and the excited state of the Os- ion to be 1.07780(12) eV and 0.553(3) eV, respectively. These values are consistent with those calculated in. Here our investigation, using the recent complex angular momentum methodology wherein is embedded the crucial electron-electron correlations and the vital core polarization interaction, has found that the near threshold electron-Os elastic scattering total cross section (TCS) is characterized by three stable bound states of the Os- ion formed as resonances during the slow electron collision, with BEs of 1.910 eV, 1.230 eV and 0.224 eV. The new extracted electron affinity (EA) value from the TCS of 1.910 eV for the Os atom is significantly different from that measured in. Our calculated elastic differential cross sections (DCSs) also yield the relevant BEs for the ground and the two excited states of the Os- ion. The complex characteristic resonance structure in the TCS for the Os atom is ideal for catalysis, but makes it difficult to execute the Wigner threshold law in describing the threshold detachment behavior of complex atoms and extracting the reliable attendant EAs. Supported by U.S. DOE, AFOSR and CAU CFNM, NSF-CREST Program.

  18. Non-resonant elastic scattering of low-energy photons by atomic sodium confined in quantum plasmas

    SciTech Connect

    Ghosh, Avijit Ray, Debasis

    2015-03-15

    The non-resonant elastic scattering of low-energy photons by the bound valence electron in the ground state 3s of atomic sodium confined in quantum plasmas is investigated theoretically. The incident photon energy is assumed to be much smaller than the 3s-3p excitation energy. The alkali atom sodium is first formulated as an effective one-electron problem in which the attractive interaction between the valence electron and the atomic ion core is simulated by a spherically symmetric model potential. The Shukla-Eliasson oscillatory exponential cosine screened-Coulomb potential model is then used to mimic the effective two-body (valence-core) interaction within quantum plasmas. Non-relativistic calculations performed within the electric dipole approximation indicate that the non-resonant elastic photon scattering cross-section undergoes a dramatic growth by several orders of magnitude as the quantum wave number increases. A qualitative explanation of this phenomenon is presented. In the absence of the oscillatory cosine screening term, a similar growth is observed at larger values of the quantum wave number. Our computed relevant atomic data are in very good agreement with the experimental as well as the previous theoretical data for the zero-screening (free atom) case, and with the very limited, accurate theoretical results available for the case of exponential screened-Coulomb two-body interaction, without the cosine screening term.

  19. Sharp low-energy feature in single-particle spectra due to forward scattering in d-wave cuprate superconductors.

    PubMed

    Hong, Seung Hwan; Bok, Jin Mo; Zhang, Wentao; He, Junfeng; Zhou, X J; Varma, C M; Choi, Han-Yong

    2014-08-01

    There is an enormous interest in the renormalization of the quasiparticle (qp) dispersion relation of cuprate superconductors both below and above the critical temperature T_{c} because it enables the determination of the fluctuation spectrum to which the qp's are coupled. A remarkable discovery by angle-resolved photoemission spectroscopy (ARPES) is a sharp low-energy feature (LEF) in qp spectra well below the superconducting energy gap but with its energy increasing in proportion to T_{c} and its intensity increasing sharply below T_{c}. This unexpected feature needs to be reconciled with d-wave superconductivity. Here, we present a quantitative analysis of ARPES data from Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} (Bi2212) using Eliashberg equations to show that the qp scattering rate due to the forward scattering impurities far from the Cu-O planes is modified by the energy gap below T_{c} and shows up as the LEF. This is also a necessary step to analyze ARPES data to reveal the spectrum of fluctuations promoting superconductivity. PMID:25126930

  20. Low-energy excitations and the fast process of polystyrene thin supported films studied by inelastic and quasielastic neutron scattering

    SciTech Connect

    Inoue, Rintaro; Kanaya, Toshiji; Nishida, Koji; Tsukushi, Itaru; Shibata, Kaoru

    2006-08-15

    We studied the low-energy excitations in the meV region as well as the picosecond fast process in polystyrene thin supported films using inelastic and quasielastic neutron scattering in a temperature range from 11 to 430 K, covering the bulk glass transition temperature T{sub g}. It was found that the mean square displacement decreased with the film thickness below and above the glass transition temperature T{sub g}, suggesting that the hardening occurs with decreasing the film thickness. Corresponding to the decrease in , it was also found that the density of phonon states G({omega}) decreased with film thickness. This decrease occurs mainly in the Debye mode while the contribution of the boson peak mode also decreases with the film thickness without changing the boson peak energy. As for the fast process, which appeared above at about 150 K as a quasielastic scattering, the fraction A{sub fast}(Q) decreased with the film thickness in a similar manner with the boson peak without changing the relaxation rate, suggesting a common origin for the boson peak and the fast process. These observations showing the hardening were well explained by assuming a hard dense layer at the interface, where the numbers of the boson peak mode as well as the fast process are less than the bulk state.

  1. Sharp low-energy feature in single-particle spectra due to forward scattering in d-wave cuprate superconductors.

    PubMed

    Hong, Seung Hwan; Bok, Jin Mo; Zhang, Wentao; He, Junfeng; Zhou, X J; Varma, C M; Choi, Han-Yong

    2014-08-01

    There is an enormous interest in the renormalization of the quasiparticle (qp) dispersion relation of cuprate superconductors both below and above the critical temperature T_{c} because it enables the determination of the fluctuation spectrum to which the qp's are coupled. A remarkable discovery by angle-resolved photoemission spectroscopy (ARPES) is a sharp low-energy feature (LEF) in qp spectra well below the superconducting energy gap but with its energy increasing in proportion to T_{c} and its intensity increasing sharply below T_{c}. This unexpected feature needs to be reconciled with d-wave superconductivity. Here, we present a quantitative analysis of ARPES data from Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} (Bi2212) using Eliashberg equations to show that the qp scattering rate due to the forward scattering impurities far from the Cu-O planes is modified by the energy gap below T_{c} and shows up as the LEF. This is also a necessary step to analyze ARPES data to reveal the spectrum of fluctuations promoting superconductivity.

  2. Precise determination of the low-energy hadronic contribution to the muon g -2 from analyticity and unitarity: An improved analysis

    NASA Astrophysics Data System (ADS)

    Ananthanarayan, B.; Caprini, Irinel; Das, Diganta; Imsong, I. Sentitemsu

    2016-06-01

    The two-pion low-energy contribution to the anomalous magnetic moment of the muon, aμ≡(g -2 )μ/2 , expressed as an integral over the modulus squared of the pion electromagnetic form factor, brings a relatively large contribution to the theoretical error, since the low accuracy of experimental measurements in this region is amplified by the drastic increase of the integration kernel. We derive stringent constraints on the two-pion contribution by exploiting analyticity and unitarity of the pion electromagnetic form factor. To avoid the poor knowledge of the modulus of this function, we use instead its phase, known with high precision in the elastic region from Roy equations for pion-pion scattering via the Fermi-Watson theorem. Above the inelastic threshold we adopt a conservative integral condition on the modulus, determined from data and perturbative QCD. Additional high precision data on the modulus in the range 0.65-0.71 GeV, obtained from e+e- annihilation and τ -decay experiments, are used to improve the predictions on the modulus at lower energies by means of a parametrization-free analytic extrapolation. The results are optimal for a given input and do not depend on the unknown phase of the form factor above the inelastic threshold. The present work improves a previous analysis based on the same technique, including more experimental data and employing better statistical tools for their treatment. We obtain for the contribution to aμ from below 0.63 GeV the value (133.258 ±0.723 )×10-10 , which amounts to a reduction of the theoretical error by about 6 ×10-11 .

  3. Probing ultrathin film continuity and interface abruptness with x-ray photoelectron spectroscopy and low-energy ion scattering

    SciTech Connect

    Zhang, Wenyu; Nahm, Rambert K.; Engstrom, James R.; Ma, Paul F.

    2013-11-15

    The authors have examined ultrathin (≤10 Å) tantalum nitride (TaN{sub x}) thin films deposited by atomic layer deposition (ALD) on three surfaces relevant to interconnect layers in microelectronic devices: thermally grown SiO{sub 2}; a Cu thin film grown by physical vapor deposition, and a carbon-doped SiO{sub 2} porous low-κ thin film. The authors have employed ex situ angle-resolved x-ray photoelectron spectroscopy (ARXPS), low-energy ion scattering spectroscopy (LEISS), and atomic force microscopy (AFM) to determine the continuity of these thin films, and by implication, the abruptness of the thin film/substrate interface. On SiO{sub 2} and low-κ, the authors find similar results: both ARXPS and AFM indicate that smooth, uniform thin films are deposited, consistent with nearly layer-by-layer growth of TaN{sub x} on these surfaces. Examination of these films using LEISS reveals that while the 10 Å TaN{sub x} thin films are continuous, the 5 Å TaN{sub x} thin films are not continuous and may possess on the order of ∼10% exposed substrate in the form of small subnanometer inclusions. On Cu, the situation is quite different. The TaN{sub x} thin films on these surfaces are not continuous, and our results point to a mixed layer of TaN{sub x} and Cu forming during ALD. In all cases, if one were to rely solely on results from ARXPS, the picture would be incomplete as the results from LEISS are ultimately decisive concerning thin film continuity.

  4. Low-energy electron scattering in carbon-based materials analyzed by scanning transmission electron microscopy and its application to sample thickness determination.

    PubMed

    Pfaff, M; Müller, E; Klein, M F G; Colsmann, A; Lemmer, U; Krzyzanek, V; Reichelt, R; Gerthsen, D

    2011-07-01

    High-angle annular dark-field scanning transmission electron microscopy (HAADF STEM) at low energies (≤30 keV) was used to study quantitatively electron scattering in amorphous carbon and carbon-based materials. Experimental HAADF STEM intensities from samples with well-known composition and thickness are compared with results of Monte Carlo simulations and semiempirical equations describing multiple electron scattering. A well-defined relationship is found between the maximum HAADF STEM intensity and sample thickness which is exploited (a) to derive a quantitative description for the mean quadratic scattering angle and (b) to calculate the transmitted HAADF STEM intensity as a function of the relevant materials parameters and electron energy. The formalism can be also applied to determine TEM sample thicknesses by minimizing the contrast of the sample as a function of the electron energy.

  5. Low-energy electron scattering from CO. 2: Ab-initio study using the frame-transformation theory

    NASA Technical Reports Server (NTRS)

    Chandra, N.

    1976-01-01

    The Wigner-Eisenbud R matrix method has been combined with the frame transformation theory to study electron scattering from molecular systems. The R matrix, calculated at the boundary point of the molecular core radius, has been transformed to the space frame in order to continue the solution of the scattering equations in the outer region where rotational motion of the nuclei is taken into account. This procedure has been applied to a model calculation of thermal energy electron scattering from CO.

  6. Crossover from inelastic magnetic scattering of Cooper pairs to spin-wave dispersion produces the low-energy kink structure in the spectra of cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Das, Tanmoy; Markiewicz, R. S.; Bansil, A.

    2012-04-01

    We present GW-based-self-energy calculations for the state of the coexisting spin-density-wave and d-wave superconductivity in a series of cuprate superconductors. The spin-resonance spectrum is found to exhibit the typical “hourglass” form whose upward and downward dispersion branches come from the gapped-spin-wave and magnetic scattering, of Cooper pairs, respectively. We show that the crossover between these two different dispersion features leads to an abrupt change of slope in the quasiparticle self-energy, and hence, the low-energy kink commences in the single-particle quasiparticle spectrum. The calculated electron-boson-coupling strength agrees well with experimental data as a function of temperature, doping, and material. The results demonstrate that electronic correlations dominate the quasiparticle spectra of cuprates near the low-energy kink, suggesting a relatively smaller role for phonons in this energy range.

  7. Complementary low energy ion scattering and X-ray photoelectron spectroscopy characterization of polystyrene submitted to N 2/H 2 glow discharge

    NASA Astrophysics Data System (ADS)

    Bonatto, F.; Rovani, S.; Kaufmann, I. R.; Soares, G. V.; Baumvol, I. J. R.; Krug, C.

    2012-02-01

    Low energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS) were used to access the elemental composition and chemical bonding characteristics of polystyrene (PS) surfaces sequentially treated by corona and glow discharge (plasma) processing in N 2/H 2 ambient. The latter has shown activity as suppressor of pathogenic Staphylococcus epidermidis biofilms. LEIS indicated that oxygen from the corona discharge process is progressively replaced by nitrogen at the PS surface. XPS shows C dbnd N and N sbnd C dbnd O chemical groups as significant inhibitors of bacterial adhesion, suggesting application in medical devices.

  8. Angular and charge state distributions of highly charged ions scattered during low energy surface-channeling interactions with Au(110)

    SciTech Connect

    Meyer, F.W.; Folkerts, L.; Schippers, S.

    1994-10-01

    The authors have measured scattered projectile angular and charge state distributions for 3.75 keV/amu O{sup q+} (3 {le} q {le} 8) and 1.2 keV/amu Ar{sup 1+} (3 {le} q {le} 14) ions grazingly incident along the [110] and [100] directions of a Au(110) single crystal target. Scattered projectile angular distribution characteristic of surface channeling are observed. For both incident species, the dominant scattered charge fraction is neutral, which varies only by a few percent as a function of incident charge state. Significant O{sup {minus}} formation is observed, which manifests a distinct velocity threshold. For incident Ar projectiles with open L-shells, the positive scattered charge fractions, while always less than about 10%, increase linearly with increasing number of initial L-shell vacancies.

  9. Low-energy reactive ion scattering as a probe of surface femtochemical reaction: H+ and H- formation on ionic compound surfaces

    NASA Astrophysics Data System (ADS)

    Souda, R.; Suzuki, T.; Kawanowa, H.; Asari, E.

    1999-01-01

    Capture and loss of valence electrons during low-energy (50-500 eV) proton scattering from some alkali-halide surfaces such as LiCl, NaCl, and KF have been investigated in comparison with those from the TiO2(110) and Cs-adsorbed Si(100) surfaces. The primary H+ ion survives neutralization when scattered from the highly ionized target species existing on the surface. For H- ion formation, a close atomic encounter with individual target ions is found to be important; the H- ion is formed more efficiently on the cationic site than on the anionic site despite the fact that the valence electron is spacially localized on the latter. This is because the charge state of scattered hydrogen is determined during a transient chemisorption state and amphoteric hydrogen tends to be coordinated negatively (positively) on the cationic site (the anionic site). The final charge state of scattered hydrogen is fixed at a certain bond-breaking distance (˜5.0 a.u.) from the surface where the well-defined atomic orbital of hydrogen evolves. The competing nonlocal resonance tunneling is suppressed at the ionic-compound surfaces due to the existence of a large band gap, so that hydrogen is scattered without losing the memory of such a transient chemisorption state.

  10. Neutron Scattering Study of Low Energy Magnetic Excitation in superconducting Te-vapor annealed under-doped FeTeSe

    NASA Astrophysics Data System (ADS)

    Xu, Zhijun; Yi, Ming; Xu, Guangyong; Shneeloch, J. A.; Matsuda, Masaaki; Chi, Songxue; Gu, Genda; Tranquada, J. M.; Birgeneau, R. J.

    To study the interplay between magnetism and superconductivity, we have performed neutron scattering and magnetization measurements on a Te vapor annealed single crystal Fe1 +yTe0.8Se0.2 (Tc~13K) sample. Te vapor annealed process is found to reduce/remove the excess Fe in the as-grown sample and make the under-doped originally non-superconducting sample become good superconducting sample. Our neutron scattering studies show both spin gap and spin resonance found in the Te vapor annealed superconducting sample. Comparing to commensurate spin resonance in as-grown optimal-doped sample, the spin resonance of Te annealed sample only shows up at the clearly incommensurate positions. The temperature and energy dependence of low energy magnetic excitations are also measured in the sample. This work is supported by the Office of Basic Energy Sciences, DOE.

  11. Determination of {sup 16}O and {sup 18}O sensitivity factors and charge-exchange processes in low-energy ion scattering

    SciTech Connect

    Tellez, H.; Chater, R. J.; Fearn, S.; Symianakis, E.; Kilner, J. A.; Brongersma, H. H.

    2012-10-08

    Quantitative analysis in low-energy ion scattering (LEIS) requires an understanding of the charge-exchange processes to estimate the elemental sensitivity factors. In this work, the neutralization of He{sup +} scattered by {sup 18}O-exchanged silica at energies between 0.6 and 7 keV was studied. The process is dominated by Auger neutralization for E{sub i} < 0.8 keV. An additional mechanism starts above the reionization threshold. This collision-induced neutralization becomes the dominant mechanism for E{sub i} > 2 keV. The ion fractions P{sup +} were determined for Si and O using the characteristic velocity method to quantify the surface density. The {sup 18}O/{sup 16}O sensitivity ratio indicates an 18% higher sensitivity for the heavier O isotope.

  12. Low-energy dispersion of dynamic charge stripes in La1.75Sr0.25NiO4 observed with inelastic neutron scattering

    NASA Astrophysics Data System (ADS)

    Zhong, Ruidan; Tranquada, John; Gu, Genda; Reznik, Dmitry; Winn, Barry

    The dynamic stripe correlations have been the subject of intense research, owing to the possible links with high-Tc superconductivity. In light of a recently published, direct observation of charge-stripe fluctuations in La2-xSrxNiO4 using inelastic neutron scattering, we did a follow-up neutron experiment on a x=0.25 sample to characterize the low-energy dispersion of these dynamic charge stripes using the HYSPEC instrument at the Spallation Neutron Source. The scattering signals are collected in the vicinity of a charge-order peak with a large wave vector (4.4, 3, 0), where dynamic spin-stripe correlations are negligible. Mapping the low-energy charge-stripe fluctuations in a wide temperature range, we observe a finite dispersion along the stripe-modulation direction at T >=160K where the charge stripes become disordered, while the steep dispersion in the orthogonal direction is not resolved. Work at BNL supported by Office of Basic Energy Sciences, US DOE, under Contract No. DE-SC00112704.

  13. Adsorption of Iodine and Potassium on Bi2Sr2CaCu2O8+δ Investigated by Low Energy Alkali Ion Scattering

    SciTech Connect

    Gu, G.D.; Gann, R.D.; Cao, J.X.; Wu, R.Q.; Wen, J.; Xu, Z.; Gu, G.D.; Yarmoff, J.A.

    2010-01-01

    The adsorption of K and I on the surface of the high-T{sub c} cuprate BSCCO-2212 is investigated with low-energy (0.8 to 2 keV) Na{sup +} ion scattering and density functional theory (DFT). Samples were cleaved in ultrahigh vacuum and charge-resolved spectra of the scattered ions were collected with time-of-flight. The spectra contain a single peak representing Na scattered from Bi, as the clean surfaces are terminated by BiO. The neutralization of scattered Na depends on the local potential above the target site, and the angular dependence indicates that the clean surface has an inhomogeneous potential. Neutralization is dependent on the coverage of I, but independent of K adsorption. DFT suggests high-symmetry sites for the adsorption of both I and K, and that the potential above the Bi sites is altered by I by an amount consistent with the experimental findings, while the potential is not affected by K adsorption. DFT also enables an experimental determination of the 'freezing distance,' which is the effective point beyond which charge exchange does not occur, to be 1.6 {+-} 0.1 {angstrom} from the outermost Bi layer.

  14. Possibilities of studying the structure of halo nuclei in reactions of quasifree proton scattering at low energies

    SciTech Connect

    Zuyev, S. V. Kasparov, A. A.; Konobeevski, E. S.

    2015-07-15

    The possibility of experimentally studying the structure of halo nuclei in reactions induced by quasifree proton scattering on clusters of these nuclei is considered. Quasifree proton scattering on {sup 6}He, {sup 4}He, {sup 4}n, {sup 2}n, and n clusters in inverse kinematics is considered for the example of the {sup 8}He nucleus. Angular and energy distributions of secondaries are obtained for various representations of the cluster structure of the {sup 8}He nucleus. It is clearly shown that, in the angular and energy distributions of secondaries, one can single out regions that receive dominant contributions from reactions on specific clusters and which correspond to concrete cluster configurations of halo nuclei. Possible relevant experiments are proposed.

  15. How low-energy weak reactions can constrain three-nucleon forces and the neutron-neutron scattering length.

    PubMed

    Gårdestig, A; Phillips, D R

    2006-06-16

    We show that chiral symmetry and gauge invariance enforce relations between the short-distance physics that occurs in a number of electroweak and pionic reactions on light nuclei. Within chiral perturbation theory, this is manifested via the appearance of the same axial isovector two-body contact term in pi(-)d --> nngamma, p-wave pion production in NN collisions, tritium beta decay, pp fusion, nud scattering, and the hep reaction. Using a Gamow-Teller matrix element obtained from calculations of pp fusion as input, we compute the neutron spectrum obtained in pi(-)d --> nngamma. With the short-distance physics in this process controlled from pp --> de(=)nu(e), the theoretical uncertainty in the nn scattering length extracted from pi(-)d --> nngamma is reduced by a factor larger than 3, to approximately < or = 0.05 fm. PMID:16803373

  16. Geometries and focal properties of two electron-lens systems useful in low-energy electron or ion scattering.

    PubMed

    Chutjian, A

    1979-03-01

    Geometries and focal properties are given for two types of electron-lens systems commonly needed in electron scattering. One is an electron gun which focuses electrons from a thermionic emitter onto a fixed point (target) over a wide range of final energies. The other is an electron analyzer system which focuses scattered electrons of variable energy onto a fixed position (e.g., the entrance plane of an analyzer) at fixed energy with a zero final beam angle. Analyzer-system focusing properties are given for superelastic, elastic, and inelastically-scattered electrons. Computer calculations using recent, accurate tube-lens focal properties are used to compute lens voltages, locations and diameters of all pupils and windows, and filling factors and asymptotic rays throughout each lens system. Focus voltages as a function of electron energy and energy change are given, and limits of operation of each system discussed. Both lens systems have been in routine use for several years, and good agreement has been consistently found between calculated and operating lens voltages.

  17. Simple model of bulk and surface excitation effects to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes

    SciTech Connect

    Kyriakou, Ioanna; Emfietzoglou, Dimitris; Garcia-Molina, Rafael; Abril, Isabel; Kostarelos, Kostas

    2011-09-01

    The effect of bulk and surface excitations to inelastic scattering in low-energy electron beam irradiation of multi-walled carbon nanotubes (MWNTs) is studied using the dielectric formalism. Calculations are based on a semiempirical dielectric response function for MWCNTs determined by means of a many-pole plasmon model with parameters adjusted to available experimental spectroscopic data under theoretical sum-rule constrains. Finite-size effects are considered in the context of electron gas theory via a boundary correction term in the plasmon dispersion relations, thus, allowing a more realistic extrapolation of the electronic excitation spectrum over the whole energy-momentum plane. Energy-loss differential and total inelastic scattering cross sections as a function of electron energy and distance from the surface, valid over the energy range {approx}50-30,000 eV, are calculated with the individual contribution of bulk and surface excitations separated and analyzed for the case of normally incident and escaping electrons. The sensitivity of the results to the various approximations for the spatial dispersion of the electronic excitations is quantified. Surface excitations are shown to have a strong influence upon the shape and intensity of the energy-loss differential cross section in the near surface region whereas the general notion of a spatially invariant inelastic mean free path inside the material is found to be of good approximation.

  18. Low-energy elastic and inelastic scattering of electrons from SO{sub 2} using the R-matrix method

    SciTech Connect

    Gupta, Monika; Baluja, K. L.

    2006-04-15

    R-matrix method is used to calculate elastic differential, integral, and momentum transfer cross sections for electron-SO{sub 2} collision. The electron-impact excitation cross sections for first seven low-lying electronic excited states of SO{sub 2} molecule from the ground state of SO{sub 2} molecule have been calculated for the first time. Sixteen low-lying electronic states of SO{sub 2} molecule are included in the close coupling expansion of the wave function of the entire scattering system, which have vertical excitation energies up to 10.51 eV. Configuration-interaction (CI) wave functions are used to calculate these excitation energies. In our CI model, we keep the core 14 electrons frozen in doubly occupied molecular orbitals 1a{sub 1}, 2a{sub 1}, 3a{sub 1}, 4a{sub 1}, 1b{sub 1}, 1b{sub 2}, 2b{sub 2} and the remaining 18 electrons span the relevant active space: 5a{sub 1}, 6a{sub 1}, 7a{sub 1}, 8a{sub 1}, 9a{sub 1}, 2b{sub 1}, 3b{sub 1}, 3b{sub 2}, 4b{sub 2}, 5b{sub 2}, 6b{sub 2}, and 1a{sub 2}. Our calculated dipole moment of the ground state of SO{sub 2} at its equilibrium geometry is 0.79 a.u., which is in reasonable agreement with the corresponding experimental value 0.64 a.u. Our calculations detect one bound SO{sub 2}{sup -} state ({sup 2}B{sub 1}) at the equilibrium geometry of SO{sub 2} molecule. Both shape as well as core-excited shape resonances have been identified in the present work and are correlated with the experimental results on dissociative electron attachment study. A detailed analysis of resonances is provided. Cross sections are reported for the electron impact energy range 0-15 eV. All cross section calculations are performed in the fixed-nuclei approximation at the experimental equilibrium geometry of the ground state of SO{sub 2} molecule. We have also investigated dependence of resonances on the geometry of SO{sub 2} molecule to probe the possible pathways for dissociation of resulting negative ion upon electron attachment. We

  19. In vacuo growth studies of Ru thin films on Si, SiN, and SiO2 by high-sensitivity low energy ion scattering

    NASA Astrophysics Data System (ADS)

    Coloma Ribera, R.; van de Kruijs, R. W. E.; Sturm, J. M.; Yakshin, A. E.; Bijkerk, F.

    2016-08-01

    In vacuo high-sensitivity low energy ion scattering (HS-LEIS) has been used to investigate the initial growth stages of DC sputtered Ru on top of Si, SiN, and SiO2. The high surface sensitivity of this technique allowed an accurate determination of surface coverages and thicknesses required for closing the Ru layer on all three substrates. The Ru layer closes (100% Ru surface signal) at about 2.0, 3.2, and 4.7 nm on top of SiO2, SiN, and Si, respectively. In-depth Ru concentration profiles can be reconstructed from the Ru surface coverages when considering an error function like model. The large intermixing (4.7 nm) for the Ru-on-Si system is compared to the reverse system (Si-on-Ru), where only 0.9 nm intermixing occurs. The difference is predominantly explained by the strong Si surface segregation that is observed for Ru-on-Si. This surface segregation effect is also observed for Ru-on-SiN but is absent for Ru-on-SiO2. For this last system, in vacuo HS-LEIS analysis revealed surface oxygen directly after deposition, which suggests an oxygen surface segregation effect for Ru-on-SiO2. In vacuo XPS measurements confirmed this hypothesis based on the reaction of Ru with oxygen from the SiO2, followed by oxygen surface segregation.

  20. Theory of low energy excitations in resonant inelastic x-ray scattering for rare-earth systems: Yb compounds as typical examples

    NASA Astrophysics Data System (ADS)

    Kotani, A.

    2011-04-01

    Theoretical predictions are given for low energy excitations, such as crystal field excitations and Kondo resonance excitations, to be detected by high-resolution measurements of resonant inelastic x-ray scattering (RIXS) of rare-earth materials with Yb compounds as typical examples. Crystal field excitations in the Yb 3d RIXS of a Yb3+ ion in the cubic crystal field are formulated, and the calculation of RIXS spectra for YbN is done. Kondo resonance excitations revealed in the Yb 3d RIXS spectra are calculated for mixed-valence Yb compounds, Yb1-xLuxAl3, in the leading term approximation of the 1/Nf expansion method with a single impurity Anderson model. It is emphasized that the high-resolution RIXS with polarization dependence is a powerful tool to study the crystal field levels together with their symmetry and also the Kondo bound state in rare-earth compounds. Some in-depth discussions are given on the polarization effects of RIXS, including 4d and 2p RIXS spectra, the coherence effect of the Kondo bound states, and the importance of the high-resolution RIXS spectra for condensed matter physics under extreme conditions.

  1. Threshold photoelectron source for the study of low-energy electron scattering: Total cross section for electron scattering from krypton in the energy range from 14 meV to 20 eV

    SciTech Connect

    Kurokawa, M.; Kitajima, M.; Toyoshima, K.; Odagiri, T.; Kato, H.; Kawahara, H.; Hoshino, M.; Tanaka, H.; Ito, K.

    2010-12-15

    An experimental technique for the measurement of the total cross section for electron scattering from atoms and molecules at high resolution is described. The total cross sections for electron scattering from Kr in the energy range from 14 meV to 20 eV obtained with the technique are also reported. The present technique employs a combination of the penetrating field technique and the threshold photoionization of rare-gas atoms using synchrotron radiation as an electron source in order to produce a high-resolution electron beam at very low energy. The characteristics of the electron sources were determined by measuring the ionizing photon energy dependence of photoelectron yield. Absolute total cross sections for electron scattering are obtained by the attenuation method. The measured absolute values of the total cross sections for electron scattering from Kr agree with those obtained by other groups down to 175 meV, above which several experimental works have been reported. Below 175 meV, the present results generally agree with theoretical cross sections down to 14 meV. The resonant structures in the total cross sections due to Kr{sup -} (4p{sup 5}5s{sup 2} {sup 2}P{sub 3/2}) and the Kr{sup -} (4p{sup 5}5s{sup 2} {sup 2}P{sub 1/2}) Feshbach resonances are also reported. The resolution of the present setup has been estimated from a fit of the measured profile of the Kr{sup -} (4p{sup 5}5s{sup 2} {sup 2}P{sub 3/2}) resonance by the theoretical curve obtained from the resonant scattering theory.

  2. Localization of alkali metal ions in sodium-promoted palladium catalysts as studied by low energy ion scattering and transmission electron microscopy

    SciTech Connect

    Liotta, L.F.; Deganello, G.; Delichere, P.

    1996-12-01

    Three series of palladium-based catalysts have been studied by Low Energy Ion Scattering (LEIS) and Transmission Electron Microscopy (TEM). The first series is comprised of Na-Pd/SiO{sub 2} catalysts, obtained by addition of palladium to a silica support and by further addition of sodium ions with a Na/Pd atomic ratio (R) equal to 0,6.4 and 25.6. The second series consists of palladium catalysts supported on natural pumice, in which, due to a different loading of supported palladium, R{prime}, the (Na+K)/Pd atomic ratio, is equal to 17.0 and 39.4. The third series is represented by two palladium-based catalysts supported on {open_quotes}model pumices,{close_quotes} synthetic silico-aluminates, obtained by sol-gel techniques, with a different amount of sodium, and R equal to 2.1 and 6.1 respectively. LEIS experiments and electron microscopy demonstrate a different location of alkali metal ions in the first two series: in the Na-Pd/SiO{sub 2} catalysts sodium is distributed in a way which is not uniform on the support and on the palladium metal, which is partly decorated with Na ions, whereas in the Pd/natural-pumice series the palladium surface is sodium-free. The results on the third series of catalysts, Pd/model pumice, are not definitive on the basis of the LEIS and TEM analyses, but by FTIR study of CO and CO{sub 2} adsorption, the decoration of palladium by sodium ions could be excluded. The results confirm the importance of the alkali metal ion location in alkali-promoted palladium catalysts and open new possibilities in the design of palladium-supported catalysts by a better control of promoter location. 18 refs., 5 figs., 2 tabs.

  3. Measurement of the Generalized Polarizabilities of the Proton in Virtual Scattering at Q2=0.92 and 1.76 GeV2: I. Low Energy Expansion Analysis

    SciTech Connect

    Stephanie Jaminion; Natalie Degrande; Geraud Laveissiere; Christophe Jutier; Luminita Todor; Rachele Di Salvo; L. Van Hoorebeke

    2003-12-01

    Virtual Compton Scattering is studied at the Thomas Jefferson National Accelerator Facility at low Center-of-Mass energies, below pion threshold. Following the Low Energy Theorem for the ep {yields} ep gamma process, we obtain values for the two structure functions Pll-Ptt/epsilon and Plt at four-momentum transfer squared Q2=0.92 and 1.76 GeV2.

  4. ATOMIC AND MOLECULAR PHYSICS: High order correlation-polarization potential for vibrational excitation scattering of diatomic molecules by low-energy electrons

    NASA Astrophysics Data System (ADS)

    Feng, Hao; Sun, Wei-Guo; Zeng, Yang-Yang

    2009-11-01

    This paper introduces a correlation-polarization potential with high order terms for vibrational excitation in electron-molecule scattering. The new polarization potential generalizes the two-term approximation so that it can better reflect the dependence of correlation and polarization effects on the position coordinate of the scattering electron. It applies the new potential on the vibrational excitation scattering from N2 in an energy range which includes the 2Πg shape resonance. The good agreement of theoretical resonant peaks with experiments shows that polarization potentials with high order terms are important and should be included in vibrational excitation scattering.

  5. Inelastic neutron scattering studies on the incommensurate-to-commensurate transformation of low energy magnetic excitations in Fe1 + δ - y(Ni / Cu) y Te1 - x Sex

    NASA Astrophysics Data System (ADS)

    Xu, Zhijun; Wen, Jinsheng; Schneeloch, John; Zhao, Yang; Matsuda, Masaaki; Ku, Wei; Liu, Xuerong; Gu, Genda; Lee, D.-H.; Birgeneau, R. J.; Tranquada, J. M.; Xu, Guangyong

    2013-03-01

    We have performed a series of neutron scattering and magnetization measurements on Fe1 + δ - y(Ni / Cu) y Te1 - x Sex system to study the interplay between magnetism and superconductivity. Both non-superconducting and superconducting samples with Tc 8 ~15K are studied. The low energy magnetic excitations of all samples at T > >Tc consist of two incommensurate vertical columns. They change to a distinctly different U-shaped dispersion at T >Tc for the superconducting samples and the transition temperature depend on the composition. On the other hand, for all non-superconducting samples, there is no clear temperature dependence, and the low energy magnetic excitations remain two columns for temperatures down to 1.5 K. Work is supported by the Office of Basic Energy Sciences, DOE.

  6. Measurement of the spin-dependent asymmetry in {sup 3}H{rvec e}({ital {rvec e}},{ital e}{prime}) inelastic scattering at low energy transfer

    SciTech Connect

    Jones, C.E.; Arrington, J.; Beise, E.J.; Bray, B.; Carr, R.W.; Filippone, B.W.; Gao, H.; Lung, A.; McKeown, R.D.; Mueller, B.; Pitt, M.L.; DeSchepper, D.; Dodson, G.; Dow, K.; Ent, R.; Farkhondeh, M.; Hansen, J.; Korsch, W.; Kramer, L.H.; Lee, K.; Makins, N.C.R.; Milner, R.G.; Tieger, D.R.; Welch, T.P.; Candell, E.; Napolitano, J.; Tripp, C.; Wojtsekhowski, B.B.; Lorenzon, W.

    1995-09-01

    We present the results of a measurement of the spin-dependent asymmetry in {sup 3}H{rvec e}({ital {rvec e}},{ital e}{prime}) inelastic scattering at kinematics on the low-energy transfer side of the quasielastic peak, including the region near the breakup threshold. Comparison with existing calculations based upon the plane wave impulse approximation shows significant deviation between the data and the model near the breakup threshold. Good agreement between data and theory is seen at higher energy transfer.

  7. The calculation of the contributions to low energy e+H2 scattering from sigma u+ and Pion u symmetries using the Kohn variational method

    NASA Technical Reports Server (NTRS)

    Armour, E. A. G.; Baker, D. J.; Plummer, M.

    1990-01-01

    Above incident energies of about 2 eV, the contribution to the total cross section in positron+H2 scattering from the sigma g+ symmetry is insufficient to account for the experimental value. Calculations carried out of the lowest partial waves of sigma u+ symmetry and Pion u symmetry using the Kohn variational method are described. The contributions to the total cross section from the two equivalent partial waves of Pion u symmetry significantly reduce the discrepancy with experiment up to incident energies of 4 to 5 eV. Comparisons are made with recent R-matrix calculations performed by Danby and Tennyson.

  8. Momentum-transfer, differential and spin-exchange cross sections in the elastic scattering of low-energy electrons by heavy alkali-metal atoms.

    NASA Astrophysics Data System (ADS)

    Bahrim, Cristian; Thumm, Uwe; Fabrikant, Ilya I.

    2000-06-01

    Based on the relativistic Dirac R-matrix method, we analyze various angle-dependent cross sections for electron scattering by Rb, Cs and Fr targets at energies below 3 eV. We show our angle-dependent and total spin-exchange cross sections for scattering of non-polarized (or polarized) electrons by polarized (or non-polarized) Rb, Cs and Fr targets, and we compare them with available experimental data (B. Jaduszliwer, N.D. Bhaskar, and B. Bederson Phys.Rev. A 14), 162 (1976).. The influence of relativistic effects is discussed. From the energy and angular dependence analysis of the differential cross section, we obtain clear evidence of the Cs^-(^3F^o) shape resonance at 1.528 eV, in excellent agreement with accurate experiments (W. Gehenn and E. Reichert, J.Phys. B 10), 3105 (1977).. We compare our electron momentum-transfer cross section with available data obtained in swarm experiments for Rb (Y. Nakamura, Trans. IEE of Japan 102-A), 23 (1982). and Cs (H.T. Saelee and J. Lucas, J.Phys. D 12), 1275 (1979)..

  9. Low Energy Supersymmetry Phenomenology

    SciTech Connect

    Feng, J.

    2003-06-16

    We summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, we evaluate the capabilities of various e{sup +}e{sup -}, p{bar p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, we discuss capabilities of future facilities to dis-entangle the anticipated spectrum of super-particles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. We comment upon the complementarity of proposed hadron and e{sup +}e{sup -} machines for a comprehensive study of low energy supersymmetry.

  10. Low energy supersymmetry phenomenology

    SciTech Connect

    Baer, H.; Chen, C.H.; Bartl, A.; Feng, J.; Fujii, K.; Gunion, J.; Kamon, T.; Lopez, J.L.; Kao, C.

    1995-04-01

    The authors summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, they evaluate the capabilities of various e{sup +}e{sup {minus}}, p{bar p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, they discuss capabilities of future facilities to disentangle the anticipated spectrum of super-particles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. The authors then comment upon the complementarity of proposed hadron and e{sup +}e{sup {minus}} machines for a comprehensive study of low energy supersymmetry.

  11. Low energy supersymmetry phenomenology

    SciTech Connect

    Baer, H.; Chen, C.H.; Bartl, A.

    1995-03-01

    The authors summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, they evaluate the capabilities of various e{sup +}e{sup {minus}}, p{anti p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, they discuss capabilities of future facilities to disentangle the anticipated spectrum of superparticles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. They comment upon the complementarity of proposed hadron and e{sup +}e{sup {minus}} machines for a comprehensive study of low energy supersymmetry.

  12. LOW ENERGY COUNTING CHAMBERS

    DOEpatents

    Hayes, P.M.

    1960-02-16

    A beta particle counter adapted to use an end window made of polyethylene terephthalate was designed. The extreme thinness of the film results in a correspondingly high transmission of incident low-energy beta particles by the window. As a consequence, the counting efficiency of the present counter is over 40% greater than counters using conventional mica end windows.

  13. Low-energy positron scattering by pyrimidine

    SciTech Connect

    Barbosa, Alessandra Souza; Pastega, Diego F.; Bettega, Márcio H. F.

    2015-12-28

    This work reports elastic integral and differential cross sections for positron collisions with pyrimidine, for energies up to 20 eV. The cross sections were computed with the Schwinger multichannel method in the static plus polarization approximation. We also employed the Born closure procedure to account for the long range potential due to the permanent dipole moment of the molecule. Our results are compared with the experimental total cross section of Zecca et al. [J. Phys. B 43, 215204 (2010)], the experimental grand-total, quasi-elastic integral and differential cross section of Palihawadana et al. [Phys. Rev. A 88, 12717 (2013)]. We also compare our results with theoretical integral and differential cross sections obtained by Sanz et al. [Phys. Rev. A 88, 62704 (2013)] with the R-matrix and the independent atom model with screening-corrected additivity rule methods, and with the results computed by Franz and Gianturco [Phys. Rev. A 88, 042711 (2013)] using model correlation-polarization potentials. The agreement between the theory and the experiment is encouraging.

  14. Low-energy neutrinos

    NASA Astrophysics Data System (ADS)

    Ludhova, Livia

    2016-05-01

    There exist several kinds of sources emitting neutrinos in the MeV energy range. These low-energy neutrinos from different sources can be often detected by the same multipurpose detectors. The status-of-art of the field of solar neutrinos, geoneutrinos, and the search for sterile neutrino with artificial neutrino sources is provided here; other neutrino sources, as for example reactor or high-energy neutrinos, are described elsewhere. For each of these three fields, the present-day motivation and open questions, as well as the latest experimental results and future perspectives are discussed.

  15. Ginsparg-Wilson pions scattering in a sea of staggered quarks

    NASA Astrophysics Data System (ADS)

    Chen, Jiunn-Wei; O'Connell, Donal; van de Water, Ruth; Walker-Loud, André

    2006-04-01

    We calculate isospin 2 pion-pion scattering in chiral perturbation theory for a partially quenched, mixed action theory with Ginsparg-Wilson valence quarks and staggered sea quarks. We point out that for some scattering channels, the power-law volume dependence of two-pion states in nonunitary theories such as partially quenched or mixed action QCD is identical to that of QCD. Thus one can extract infinite-volume scattering parameters from mixed action simulations. We then determine the scattering length for both 2 and 2+1 sea quarks in the isospin limit. The scattering length, when expressed in terms of the pion mass and the decay constant measured on the lattice, has no contributions from mixed valence-sea mesons, thus it does not depend upon the parameter, CMix, that appears in the chiral Lagrangian of the mixed theory. In addition, the contributions which nominally arise from operators appearing in the mixed action O(a2mq) Lagrangian exactly cancel when the scattering length is written in this form. This is in contrast to the scattering length expressed in terms of the bare parameters of the chiral Lagrangian, which explicitly exhibits all the sicknesses and lattice spacing dependence allowed by a partially quenched mixed action theory. These results hold for both 2 and 2+1 flavors of sea quarks.

  16. Ginsparg-Wilson pions scattering in a sea of staggered quarks

    SciTech Connect

    Chen, J.-W.; O'Connell, Donal; Van de Water, Ruth; Walker-Loud, Andre

    2006-04-01

    We calculate isospin 2 pion-pion scattering in chiral perturbation theory for a partially quenched, mixed action theory with Ginsparg-Wilson valence quarks and staggered sea quarks. We point out that for some scattering channels, the power-law volume dependence of two-pion states in nonunitary theories such as partially quenched or mixed action QCD is identical to that of QCD. Thus one can extract infinite-volume scattering parameters from mixed action simulations. We then determine the scattering length for both 2 and 2+1 sea quarks in the isospin limit. The scattering length, when expressed in terms of the pion mass and the decay constant measured on the lattice, has no contributions from mixed valence-sea mesons, thus it does not depend upon the parameter, C{sub Mix}, that appears in the chiral Lagrangian of the mixed theory. In addition, the contributions which nominally arise from operators appearing in the mixed action O(a{sup 2}m{sub q}) Lagrangian exactly cancel when the scattering length is written in this form. This is in contrast to the scattering length expressed in terms of the bare parameters of the chiral Lagrangian, which explicitly exhibits all the sicknesses and lattice spacing dependence allowed by a partially quenched mixed action theory. These results hold for both 2 and 2+1 flavors of sea quarks.

  17. Low-energy electron-atom bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Gould, R. J.

    1986-01-01

    This paper extends recent work providing an elementary calculation of bremsstrahlung and opacity associated with the scattering of low-energy electrons by neutral atoms and molecules. The method applies when the scattering potential is 'hard' or when the collision time is short, applying the classical soft-photon emission probability formula for arbitrary bremsstrahlung photon energy. However, now, in addition to correcting the probability factor for finite bremsstrahlung photon energy, another factor corrects for the reduced phase space available to the outgoing electron. The bremsstrahlung cross section and opacity are then computed directly from the elastic scattering cross section, determined experimentally or calculated; a small (approximately 10 percent) correction is computed from the anisotropic term in the elastic scattering cross section. The opacity is evaluated for electron scattering by H, He, and H2 using experimentally determined values for the elastic scattering cross section, and is compared with more elaborate calculations. The agreement is good (within 10 percent), indicating an accuracy for the general method comparable to variations among the results of different elaborate theoretical computations. The agreement seems to validate the basic approximation of short collision time even at large bremsstrahlung photon energy for electron energies and temperatures up to a few eV.

  18. Correlation among low-energy four-nucleon observables

    NASA Astrophysics Data System (ADS)

    Adhikari, Sadhan K.

    1981-07-01

    We study the correlation among s-wave low-energy four-nucleon observables by using a simplified dispersion theoretic (ND) approach. We find that the triton binding energy, its asymptotic normalization parameter, the deuteron exchange left-hand cut, and the nucleon-trinucleon (N-t) scattering length control the low-energy N-t system. The isospin one channel is insensitive to the asymptotic normalization parameter of the triton. The effective range function k δ for the isospin zero spin singlet N-t system has a pole whose position and residue are strongly correlated with the N-t scattering length. In this case the four-nucleon system (in our model) has an excited state whose binding energy and asymptotic normalization parameter are also correlated with the N-t scattering length. [NUCLEAR REACTIONS s-wave nucleon-trinucleon systems, spin-isospin channels, ND approach, low-energy correlations.

  19. Electron polarimetry at low energies in Hall C at JLab

    NASA Astrophysics Data System (ADS)

    Gaskell, D.

    2013-11-01

    Although the majority of Jefferson Lab experiments require multi-GeV electron beams, there have been a few opportunities to make electron beam polarization measurements at rather low energies. This proceedings will discuss some of the practical difficulties encountered in performing electron polarimetry via Mo/ller scattering at energies on the order of a few hundred MeV. Prospects for Compton polarimetry at very low energies will also be discussed. While Mo/ller scattering is likely the preferred method for electron polarimetry at energies below 500 MeV, there are certain aspects of the polarimeter and experiment design that must be carefully considered.

  20. A low energy electron magnetometer

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Wood, G. M., Jr.; Rayborn, G. H.; White, F. A.

    1979-01-01

    The concept of a highly sensitive magnetometer based on the deflection of low energy electron beams in magnetic fields is analyzed. Because of its extremely low mass and consequently high e/m ratio, a low energy electron is easily deflected in a magnetic field, thus providing a basis for very low field measurement. Calculations for a specific instrument design indicate that a low energy electron magnetometer (LEEM) can measure magnetic fields as low as 1000 nT. The anticipated performance of LEEM is compared with that of the existing high resolution magnetometers in selected applications. The fast response time of LEEM makes it especially attractive as a potential instrument for magnetic signature analysis in large engineering systems.

  1. Beam lifetime and limitations during low-energy RHIC operation

    SciTech Connect

    Fedotov, A.V.; Bai, M.; Blaskiewicz, M.; Fischer, W.; Kayran, D.; Montag, C.; Satogata, T.; Tepikian, S.; Wang, G.

    2011-03-28

    The low-energy physics program at the Relativistic Heavy Ion Collider (RHIC), motivated by a search for the QCD phase transition critical point, requires operation at low energies. At these energies, large nonlinear magnetic field errors and large beam sizes produce low beam lifetimes. A variety of beam dynamics effects such as Intrabeam Scattering (IBS), space charge and beam-beam forces also contribute. All these effects are important to understand beam lifetime limitations in RHIC at low energies. During the low-energy RHIC physics run in May-June 2010 at beam {gamma} = 6.1 and {gamma} = 4.1, gold beam lifetimes were measured for various values of space-charge tune shifts, transverse acceptance limitation by collimators, synchrotron tunes and RF voltage. This paper summarizes our observations and initial findings.

  2. Low Energy Schools in Ireland

    ERIC Educational Resources Information Center

    Heffernan, Martin

    2004-01-01

    Out of a commitment to reducing carbon dioxide emissions, Ireland's Department of Education and Science has designed and constructed two low energy schools, in Tullamore, County Offaly, and Raheen, County Laois. With energy use in buildings responsible for approximately 55% of the CO[subscript 2] released into the atmosphere and a major…

  3. Low energy neutrinos in Super-Kamiokande

    NASA Astrophysics Data System (ADS)

    Sekiya, Hiroyuki

    2016-05-01

    Super-Kamiokande (SK), a 50 kton water Cherenkov detector, observes 8B solar neutrinos via neutrino-electron elastic scattering. The analysis threshold was successfully lowered to 3.5 MeV (recoil electron kinetic energy) in SK-IV. To date SK has observed solar neutrinos for 18 years. An analysis regarding possible correlations between the solar neutrino flux and the 11 year solar activity cycle is shown. With large statistics, SK searches for distortions of the solar neutrino energy spectrum caused by the MSW resonance in the core of the sun. SK also searches for a day/night solar neutrino flux asymmetry induced by the matter in the Earth. The Super-Kamiokande Gd (SK-Gd) project is the upgrade of the SK detector via the addition of water-soluble gadolinium (Gd) salt. This modification will enable it to efficiently identify low energy anti-neutrinos. SK-Gd will pursue low energy physics currently inaccessible to SK due to backgrounds. The most important will be the world’s first observation of the diffuse supernova neutrino background. The main R&D program towards SK-Gd is EG ADS: a 200 ton, fully instrumented tank built in a new cavern in the Kamioka mine.

  4. The Low Energy Neutrino Factory

    SciTech Connect

    Bross, Alan; Geer, Steve; Ellis, Malcolm; Fernandez Martinez, Enrique; Li, Tracey; Pascoli, Silvia; Mena, Olga

    2010-03-30

    We show that a low energy neutrino factory with a baseline of 1300 km and muon energy of 4.5 GeV has an excellent physics reach. The results of our optimisation studies demonstrate that such a setup can have remarkable sensitivity to theta{sub 13} and delta for sin{sup 2}(2theta{sub 13})>10{sup -4}, and to the mass hierarchy for sin{sup 2}(2theta{sub 13})>10{sup -3}. We also illustrate the power of the unique combination of golden and platinum channels accessible to the low energy neutrino factory. We have considered both a 20 kton totally active scintillating detector and a 100 kton liquid argon detector as possible detector technologies, finding that a liquid argon detector with very good background rejection can produce sensitivity to theta{sub 13} and delta with that of the International Design Study neutrino factory.

  5. The low energy signaling network

    PubMed Central

    Tomé, Filipa; Nägele, Thomas; Adamo, Mattia; Garg, Abhroop; Marco-llorca, Carles; Nukarinen, Ella; Pedrotti, Lorenzo; Peviani, Alessia; Simeunovic, Andrea; Tatkiewicz, Anna; Tomar, Monika; Gamm, Magdalena

    2014-01-01

    Stress impacts negatively on plant growth and crop productivity, caicultural production worldwide. Throughout their life, plants are often confronted with multiple types of stress that affect overall cellular energy status and activate energy-saving responses. The resulting low energy syndrome (LES) includes transcriptional, translational, and metabolic reprogramming and is essential for stress adaptation. The conserved kinases sucrose-non-fermenting-1-related protein kinase-1 (SnRK1) and target of rapamycin (TOR) play central roles in the regulation of LES in response to stress conditions, affecting cellular processes and leading to growth arrest and metabolic reprogramming. We review the current understanding of how TOR and SnRK1 are involved in regulating the response of plants to low energy conditions. The central role in the regulation of cellular processes, the reprogramming of metabolism, and the phenotypic consequences of these two kinases will be discussed in light of current knowledge and potential future developments. PMID:25101105

  6. The low energy signaling network.

    PubMed

    Tomé, Filipa; Nägele, Thomas; Adamo, Mattia; Garg, Abhroop; Marco-Llorca, Carles; Nukarinen, Ella; Pedrotti, Lorenzo; Peviani, Alessia; Simeunovic, Andrea; Tatkiewicz, Anna; Tomar, Monika; Gamm, Magdalena

    2014-01-01

    Stress impacts negatively on plant growth and crop productivity, caicultural production worldwide. Throughout their life, plants are often confronted with multiple types of stress that affect overall cellular energy status and activate energy-saving responses. The resulting low energy syndrome (LES) includes transcriptional, translational, and metabolic reprogramming and is essential for stress adaptation. The conserved kinases sucrose-non-fermenting-1-related protein kinase-1 (SnRK1) and target of rapamycin (TOR) play central roles in the regulation of LES in response to stress conditions, affecting cellular processes and leading to growth arrest and metabolic reprogramming. We review the current understanding of how TOR and SnRK1 are involved in regulating the response of plants to low energy conditions. The central role in the regulation of cellular processes, the reprogramming of metabolism, and the phenotypic consequences of these two kinases will be discussed in light of current knowledge and potential future developments.

  7. Diffuse Galactic low energy gamma ray continuum emission

    NASA Technical Reports Server (NTRS)

    Skibo, J. G.; Ramaty, R.

    1993-01-01

    We investigate the origin of diffuse low-energy Galactic gamma-ray continuum down to about 30 keV. We calculate gamma-ray emission via bremsstrahlung and inverse Compton scattering by propagating an unbroken electron power law injection spectrum and employing a Galactic emmissivity model derived from COSB observations. To maintain the low energy electron population capable of producing the observed continuum via bremsstrahlung, a total power input of 4 x 10 exp 41 erg/s is required. This exceeds the total power supplied to the nuclear cosmic rays by about an order of magnitude.

  8. Low-Energy Proton Testing Methodology

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Marshall, Paul W.; Heidel, David F.; Schwank, James R.; Shaneyfelt, Marty R.; Xapsos, M.A.; Ladbury, Raymond L.; LaBel, Kenneth A.; Berg, Melanie; Kim, Hak S.; Phan, Anthony; Friendlich, M.R.; Rodbell, Kenneth P.; Hakey, Mark C.; Dodd, Paul E.; Reed, Robert A.; Weller, Robert A.; Mendenhall, Marcus H.; Sierawski, B.D.

    2009-01-01

    Use of low-energy protons and high-energy light ions is becoming necessary to investigate current-generation SEU thresholds. Systematic errors can dominate measurements made with low-energy protons. Range and energy straggling contribute to systematic error. Low-energy proton testing is not a step-and-repeat process. Low-energy protons and high-energy light ions can be used to measure SEU cross section of single sensitive features; important for simulation.

  9. Low-Energy Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Wiedenbeck, M. E.; ACE/CRIS Collaboration

    2002-12-01

    Cosmic rays with energies below about 10 GeV/nucleon have been measured with high precision as a result of experiments on the HEAO, Ulysses, and ACE spacecrafts. The observations provide energy spectra, elemental abundances, and isotopic composition for elements up through Z=30. They include both stable and radioactive nuclides that are synthesized in stars or are produced by nuclear fragmentation during diffusion at high energies through interstellar medium. From these data one obtains a rather detailed picture of the origin of low-energy cosmic rays. For refractory species, the cosmic-ray source composition closely resembles that of the Sun, suggesting that cosmic rays are accelerated from a well-mixed sample of interstellar matter. A chemical fractionation process has depleted the abundances of volatile elements relative to refractories. Using various radioactive clock isotopes it has been shown that particle acceleration occurs at least 105 years after supernova nucleosynthesis and that the accelerated particles diffuse in the Galaxy for approximately 15 Myr after acceleration. Energy spectra and secondary-to-primary ratios are reasonably well accounted for by models in which particles gain the bulk of their energy in a single encounter with a strong shock. Among the large number of species that have been measured, 22Ne stands out as the only nuclide with an abundance that is clearly much different than solar. To test models proposed to account for this anomaly, the data are being analyzed for predicted smaller effects on abundances of other nuclides. In addition to providing a detailed understanding of the origin and acceleration of low-energy cosmic rays, these data are providing constraints on the chemical evolution of interstellar matter. This work was supported by NASA at Caltech (under grant NAG5-6912), JPL, NASA/GSFC, and Washington U.

  10. Low-energy photon scattering experiments of 151,153Eu, 163Dy, and 165Ho and the systematics of the M1 scissors mode in odd-mass rare-earth nuclei

    NASA Astrophysics Data System (ADS)

    Nord, A.; Enders, J.; de Almeida Pinto, A. E.; Belic, D.; von Brentano, P.; Fransen, C.; Kneissl, U.; Kohstall, C.; Linnemann, A.; von Neumann-Cosel, P.; Pietralla, N.; Pitz, H. H.; Richter, A.; Stedile, F.; Werner, V.

    2003-03-01

    Nuclear resonance fluorescence experiments were performed on the rare-earth nuclei 151,153Eu, and with considerably increased sensitivity on 163Dy and 165Ho to study the fragmentation of the M1 scissors mode in odd-mass nuclei, and to clarify the puzzle of the missing total M1 strength observed for odd-mass nuclei so far. Using the bremsstrahlung photon beam of the Stuttgart Dynamitron (end point energy 4.05 MeV) and high-resolution Ge γ-ray spectrometers, detailed information was obtained on excitation energies, decay widths, transition probabilities, and branching ratios. Whereas in 151Eu only 11 weak excitations were observed, 161 and 138 excitations could be detected in the heavier nuclei 163Dy and 165Ho, respectively. The results are compared to those observed recently at the Stuttgart facility for the neighboring odd-mass nuclei 161Dy, 155,157Gd, and 159Tb. The measured total strengths increase with the mass number A. Ascribing the same portion of the dipole strength to M1 excitations as measured in the neighboring even-even nuclei, the total M1 strength deduced from the most sensitive experiment on 163Dy is comparable to those found in the neighboring even-even nuclei. The results for 163Dy and 165Ho are compared with a fluctuation analysis of the photon scattering spectra to estimate the amount of still unresolved strength eventually hidden in the background due to the extreme fragmentation of the M1 scissors mode in odd-mass rare-earth nuclei. For 165Ho, the total derived strength of B(M1)↑=2.9(5)μ2N agrees within error bars with an earlier analysis of a different measurement of the 165Ho(γ,γ') reaction. In 163Dy the method leads to an unphysical background shape, underlining the experimental observation of a significantly reduced fragmentation pattern of the dipole modes in this nucleus, which must be traced back to structure features of the Dy isotopes.

  11. Intense low energy positron beams

    SciTech Connect

    Lynn, K.G.; Jacobsen, F.M.

    1993-12-31

    Intense positron beams are under development or being considered at several laboratories. Already today a few accelerator based high intensity, low brightness e{sup +} beams exist producing of the order of 10{sup 8} {minus} 10{sup 9} e{sup +}/sec. Several laboratories are aiming at high intensity, high brightness e{sup +} beams with intensities greater than 10{sup 9} e{sup +}/sec and current densities of the order of 10{sup 13} {minus} 10{sup 14} e{sup +} sec{sup {minus}} {sup 1}cm{sup {minus}2}. Intense e{sup +} beams can be realized in two ways (or in a combination thereof) either through a development of more efficient B{sup +} moderators or by increasing the available activity of B{sup +} particles. In this review we shall mainly concentrate on the latter approach. In atomic physics the main trust for these developments is to be able to measure differential and high energy cross-sections in e{sup +} collisions with atoms and molecules. Within solid state physics high intensity, high brightness e{sup +} beams are in demand in areas such as the re-emission e{sup +} microscope, two dimensional angular correlation of annihilation radiation, low energy e{sup +} diffraction and other fields. Intense e{sup +} beams are also important for the development of positronium beams, as well as exotic experiments such as Bose condensation and Ps liquid studies.

  12. Low-Energy Sputtering Research

    NASA Technical Reports Server (NTRS)

    Ray, P. K.; Shutthanandan, V.

    1999-01-01

    An experimental study is described to measure low-energy (less than 600 eV) sputtering yields of molybdenum with xenon ions using Rutherford backscattering spectroscopy (RBS) and secondary neutral mass spectroscopy (SNMS). An ion gun was used to generate the ion beam. The ion current density at the target surface was approximately 30 (micro)A/sq cm. For RBS measurements, the sputtered material was collected on a thin aluminum strip which was mounted on a semi-circular collector plate. The target was bombarded with 200 and 500 eV xenon ions at normal incidence. The differential sputtering yields were measured using the RBS method with 1 MeV helium ions. The differential yields were fitted with a cosine fitting function and integrated with respect to the solid angle to provide the total sputtering yields. The sputtering yields obtained using the RBS method are in reasonable agreement with those measured by other researchers using different techniques. For the SNMS measurements, 150 to 600 eV xenon ions were used at 50deg angle of incidence. The SNMS spectra were converted to sputtering yields for perpendicular incidence by normalizing SNMS spectral data at 500 eV with the yield measured by Rutherford backscattering spectrometry. Sputtering yields as well as the shape of the yield-energy curve obtained in this manner are in reasonable agreement with those measured by other researchers using different techniques. Sputtering yields calculated by using two semi-spherical formulations agree reasonably well with measured data. The isotopic composition of secondary ions were measured by bombarding copper with xenon ions at energies ranging from 100 eV to 1.5 keV. The secondary ion flux was found to be enriched in heavy isotopes at low incident ion energies. The heavy isotope enrichment was observed to decrease with increasing impact energy. Beyond 700 eV, light isotopes were sputtered preferentially with the enrichment remaining nearly constant.

  13. Low-Energy Electron Interactions with Complex Targets.

    NASA Astrophysics Data System (ADS)

    Orlando, Thomas

    2006-05-01

    We have examined low-energy electron collisions with complex targets such as pristine nanoscale ice films and water/DNA interfaces by monitoring the reactive scattering processes leading to the formation of H (H^+), H2 (H2^+), O ^3PJ, O ^1D, OH^+, H^+(H2O)n and DNA fragments. This work has shown that temperature-induced changes in the yields are due to subtle geometric and electronic structure changes brought about by changes in the interfacial hydrogen bonding structure. We have then exploited the fact that the two-hole localized states governing cation production and excitations involving a1 levels are good probes of subtle structural changes in the water network. Since low-energy electrons can cause lethal damage to DNA, understanding the role of water and the DNA constituents in the damage event has recently received wide-spread attention. We have modified our multiple scattering ``path approach'' used to describe diffraction effects in stimulated desorption to calculate the diffraction and incident electron intensity at particular sections within a DNA double-strand. This approach assumes hypothetical electron scattering paths inside the target and calculates the interference of all elastically scattered components with the initial incoming wave. Constructive interference at zones localized within the DNA may locally enhance the dissociation probability.

  14. Towards Low Energy Atrial Defibrillation.

    PubMed

    Walsh, Philip; Kodoth, Vivek; McEneaney, David; Rodrigues, Paola; Velasquez, Jose; Waterman, Niall; Escalona, Omar

    2015-01-01

    transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation. PMID:26404298

  15. Towards Low Energy Atrial Defibrillation

    PubMed Central

    Walsh, Philip; Kodoth, Vivek; McEneaney, David; Rodrigues, Paola; Velasquez, Jose; Waterman, Niall; Escalona, Omar

    2015-01-01

    transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation. PMID:26404298

  16. pi+- p differential cross sections at low energies

    SciTech Connect

    H. Denz; P. Amaudruz; J.T. Brack; J. Breitschopf; P. Camerini; J.L. Clark; H. Clement; L. Felawka; E. Fragiacomo; E.F. Gibson; N. Grion; G.J. Hofman; B. Jamieson; E.L. Mathie; R. Meier; G. Moloney; D. Ottewell; O. Patarakin; J.D. Patterson; M.M. Pavan; S. Piano; K. Raywood; R.A. Ristinen; R. Rui; M.E. Sevior; G.R. Smith; J. Stahov; R. Tacik; G.J. Wagner; F. von Wrochem; D.M. Yeomans

    2005-12-03

    Differential cross sections for pi- p and pi+ p elastic scattering were measured at five energies between 19.9 and 43.3 MeV. The use of the CHAOS magnetic spectrometer at TRIUMF, supplemented by a range telescope for muon background suppression, provided simultaneous coverage of a large part of the full angular range, thus allowing very precise relative cross section measurements. The absolute normalization was determined with a typical accuracy of 5 %. This was verified in a simultaneous measurement of muon proton elastic scattering. The measured cross sections show some deviations from phase shift analysis predictions, in particular at large angles and low energies. From the new data we determine the real part of the isospin forward scattering amplitude.

  17. Influence of Packing on Low Energy Vibrations of Densified Glasses

    NASA Astrophysics Data System (ADS)

    Carini, Giovanni, Jr.; Carini, Giuseppe; D'Angelo, Giovanna; Tripodo, Gaspare; Di Marco, Gaetano; Vasi, Cirino; Gilioli, Edmondo

    2013-12-01

    A comparative study of Raman scattering and low temperature specific heat capacity has been performed on samples of B2O3, which have been high-pressure quenched to go through different glassy phases having growing density to the crystalline state. It has revealed that the excess volume characterizing the glassy networks favors the formation of specific glassy structural units, the boroxol rings, which produce the boson peak, a broad band of low energy vibrational states. The decrease of boroxol rings with increasing pressure of synthesis is associated with the progressive depression of the excess low energy vibrations until their full disappearance in the crystalline phase, where the rings are missing. These observations prove that the additional soft vibrations in glasses arise from specific units whose formation is made possible by the poor atomic packing of the network.

  18. Low energy ghosts and the Jeans' instability

    NASA Astrophysics Data System (ADS)

    Gümrükçüoǧlu, A. Emir; Mukohyama, Shinji; Sotiriou, Thomas P.

    2016-09-01

    We show that a massless canonical scalar field minimally coupled to general relativity can become a tachyonic ghost at low energies around a background in which the scalar's gradient is spacelike. By performing a canonical transformation we demonstrate that this low energy ghost can be recast, at the level of the action, in a form of a fluid that undergoes a Jeans-like instability affecting only modes with large wavelength. This illustrates that low energy tachyonic ghosts do not lead to a catastrophic quantum vacuum instability, unlike the usual high-energy ghost degrees of freedom.

  19. Solar-assisted low energy dwellings

    SciTech Connect

    Esbensen, T V

    1980-02-01

    The Zero Energy House Group was formed as a subproject of the CCMS Solar Energy Pilot Study in 1974 by seven participating countries experimenting with solar-assisted low-energy dwellings for temperate and northern European climatic conditions. A Zero Energy House is one in which solar energy is used to meet the reduced energy needs of buildings incorporating various thermal energy conservation features. This final report of the Zero Energy House Group includes brief descriptions of 13 major low-energy dwellings in the participating CCMS countries. An overall assessment of the state-of-the-art in solar-assisted low-energy dwellings is also included.

  20. Development of multichannel low-energy neutron spectrometer

    SciTech Connect

    Arikawa, Y. Nagai, T.; Abe, Y.; Kojima, S.; Sakata, S.; Inoue, H.; Utsugi, M.; Iwasa, Y.; Sarukura, N.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.; Murata, T.

    2014-11-15

    A multichannel low-energy neutron spectrometer for down-scattered neutron (DSN) measurements in inertial confinement fusion (ICF) experiments has been developed. Our compact-size 256-channel lithium-glass-scintillator-based spectrometer has been implemented and tested in ICF experiments with the GEKKO XII laser. We have performed time calibration of the 256-channel analog-to-digital convertor system used for DSN measurements via X-ray pulse signals. We have clearly observed the DD-primary fusion neutron signal and have successfully studied the detector's impulse response. Our detector is soon to be implemented in future ICF experiments.

  1. Method and apparatus for generating low energy nuclear particles

    DOEpatents

    Powell, James R.; Reich, Morris; Ludewig, Hans; Todosow, Michael

    1999-02-09

    A particle accelerator (12) generates an input particle beam having an initial energy level above a threshold for generating secondary nuclear particles. A thin target (14) is rotated in the path of the input beam for undergoing nuclear reactions to generate the secondary particles and correspondingly decrease energy of the input beam to about the threshold. The target (14) produces low energy secondary particles and is effectively cooled by radiation and conduction. A neutron scatterer (44) and a neutron filter (42) are also used for preferentially degrading the secondary particles into a lower energy range if desired.

  2. Method and apparatus for generating low energy nuclear particles

    DOEpatents

    Powell, J.R.; Reich, M.; Ludewig, H.; Todosow, M.

    1999-02-09

    A particle accelerator generates an input particle beam having an initial energy level above a threshold for generating secondary nuclear particles. A thin target is rotated in the path of the input beam for undergoing nuclear reactions to generate the secondary particles and correspondingly decrease energy of the input beam to about the threshold. The target produces low energy secondary particles and is effectively cooled by radiation and conduction. A neutron scatterer and a neutron filter are also used for preferentially degrading the secondary particles into a lower energy range if desired. 18 figs.

  3. The Science of Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Storms, Edmund

    2007-03-01

    The large literature describing the anomalous behavior attributed to cold fusion or low energy nuclear reactions has been critically described in a recently published book. Over 950 publications are evaluated allowing the phenomenon to be understood. A new class of nuclear reactions has been discovered that are able to generate practical energy without significant radiation or radioactivity. Edmund K Storms, The Science of Low Energy Nuclear Reactions, in press (2006). Also see: http://www.lenr-canr.org/StudentsGuide.htm .

  4. Structures and Low-Energy Excitations of Amorphous Gas Hydrates

    NASA Astrophysics Data System (ADS)

    Kikuchi, Tatsuya; Inamura, Yasuhiro; Onoda-Yamamuro, Noriko; Yamamuro, Osamu

    2012-09-01

    We have prepared amorphous clathrate hydrates of Ar, CD4, Xe, and SF6 by depositing mixed vapors of water and guest molecules on a substrate at ca. 10 K. The structure and vibrational density of states were investigated by neutron diffraction and inelastic scattering techniques, respectively. The radial distribution functions of the amorphous hydrates are larger than that of pure amorphous ice in the region around 4 Å (the center-edge distance of the 12-hedral cage), indicating that a local cagelike structure is maintained even in the amorphous solids. The incorporation of the guest molecules decreases the intensity of the phonon excitation below 7 meV, which is known as a low-energy excitation characteristic of amorphous ice. This may be due to the effect that the disorder, defects and distortion producing the low-energy excitation are reduced by a hydrophobic hydration between the guest and water molecules and the resultant hydrogen-bond formation. A similar effect was also observed in the libration mode of water molecules at about 60 meV. The present work has revealed the relation among the local cage formation, hydrogen bonds, and low energy excitations in amorphous hydrates that is the simplest hydrophobic hydration system (H2O--gas mixture).

  5. Low-energy electron collisions with thiophene

    NASA Astrophysics Data System (ADS)

    da Costa, R. F.; Varella, M. T. do N.; Lima, M. A. P.; Bettega, M. H. F.

    2013-05-01

    We report on elastic integral, momentum transfer, and differential cross sections for collisions of low-energy electrons with thiophene molecules. The scattering calculations presented here used the Schwinger multichannel method and were carried out in the static-exchange and static-exchange plus polarization approximations for energies ranging from 0.5 eV to 6 eV. We found shape resonances related to the formation of two long-lived π* anion states. These resonant structures are centered at the energies of 1.00 eV (2.85 eV) and 2.82 eV (5.00 eV) in the static-exchange plus polarization (static-exchange) approximation and belong to the B1 and A2 symmetries of the C2v point group, respectively. Our results also suggest the existence of a σ* shape resonance in the B2 symmetry with a strong d-wave character, located at around 2.78 eV (5.50 eV) as obtained in the static-exchange plus polarization (static-exchange) calculation. It is worth to mention that the results obtained at the static-exchange plus polarization level of approximation for the two π* resonances are in good agreement with the electron transmission spectroscopy results of 1.15 eV and 2.63 eV measured by Modelli and Burrow [J. Phys. Chem. A 108, 5721 (2004), 10.1021/jp048759a]. The existence of the σ* shape resonance is in agreement with the observations of Dezarnaud-Dandiney et al. [J. Phys. B 31, L497 (1998), 10.1088/0953-4075/31/11/004] based on the electron transmission spectra of dimethyl(poly)sulphides. A comparison among the resonances of thiophene with those of pyrrole and furan is also performed and, altogether, the resonance spectra obtained for these molecules point out that electron attachment to π* molecular orbitals is a general feature displayed by these five-membered heterocyclic compounds.

  6. Sensitivity of low energy neutrino experiments to physics beyond the standard model

    SciTech Connect

    Barranco, J.; Miranda, O. G.; Rashba, T. I.

    2007-10-01

    We study the sensitivity of future low energy neutrino experiments to extra neutral gauge bosons, leptoquarks, and R-parity breaking interactions. We focus on future proposals to measure coherent neutrino-nuclei scattering and neutrino-electron elastic scattering. We introduce a new comparative analysis between these experiments and show that in different types of new physics it is possible to obtain competitive bounds to those of present and future collider experiments. For the cases of leptoquarks and R-parity breaking interactions we found that the expected sensitivity for most of the future low energy experimental setups is better than the current constraints.

  7. Low-energy backscattering quantum orbits in above-threshold ionization

    NASA Astrophysics Data System (ADS)

    Milošević, D. B.

    2016-09-01

    Using the quantum–orbit formalism we consider the influence of the backward-scattering quantum orbits on the low-energy above-threshold ionization spectra. It is shown that the corresponding ionization rate exhibits sharp peaks for electron energies ≲ 0.1 {U}{{P}} ({U}{{P}} is the electron ponderomotive energy) at the same places where the forward-scattering-induced low-energy structures appear. The corresponding incident rescattering electron velocities are very small. Semiclassical expressions for the positions of these peaks as functions of {U}{{P}} and the ionization potential are derived.

  8. Nuclear Astrophysics and Structure Studies Using Low-energy RI Beams at CRIB

    SciTech Connect

    Yamaguchi, H.; Hashimoto, T.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kubono, S.

    2010-05-12

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Using the RI beams at CRIB, Many measurements on proton and alpha resonance scatterings, (alpha,p) reactions, and others were peformed in recent years, mainly for studying astrophysical reactions and exotic nuclear structure. Among them, the results on the {sup 7}Be+p and {sup 7}Li+alpha resonance scatterings are presented.

  9. Nuclear Astrophysics and Structure Studies Using Low-energy RI Beams at CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Hashimoto, T.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kubono, S.

    2010-05-01

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Using the RI beams at CRIB, Many measurements on proton and alpha resonance scatterings, (α,p) reactions, and others were peformed in recent years, mainly for studying astrophysical reactions and exotic nuclear structure. Among them, the results on the 7Be+p and 7Li+α resonance scatterings are presented.

  10. Studies in Low-Energy Nuclear Science

    SciTech Connect

    Carl R. Brune; Steven M. Grimes

    2010-01-13

    This report presents a summary of research projects in the area of low energy nuclear reactions and structure, carried out between March 1, 2006 and October 31, 2009 which were supported by U.S. DOE grant number DE-FG52-06NA26187.

  11. Parity violation in low-energy

    SciTech Connect

    Martin Savage

    2001-12-01

    Parity violation in low-energy nuclear observables is included in the pionless effective field theory. The model-independent relation between the parity-violating asymmetry in polarized np -> d gamma and the non-nucleon part of the deuteron anapole moment is discussed. The asymmetry in np -> d gamma computed with KSW power-counting, and recently criticized by Desplanques, is discussed.

  12. Low-energy neutrino-nucleus interactions and beta-beam neutrino

    SciTech Connect

    Jachowicz, N.; Pandey, V.

    2015-05-15

    We present an overview of neutrino-nucleus scattering at low energies with cross sections obtained within a continuum random phase approximation (CRPA) formalism. We highlight potential applications of beta-beam neutrino experiments for neutrino astrophysics. Our calculations are compared with MiniBooNe data at intermediate energies.

  13. Materials for Low-Energy Neutron Radiation Shielding

    NASA Technical Reports Server (NTRS)

    Singleterry, Robert C., Jr.; Thibeault, Sheila A.

    2000-01-01

    Various candidate aircraft and spacecraft materials were analyzed and compared in a low-energy neutron environment using the Monte Carlo N-Particle (MCNP) transport code with an energy range up to 20 MeV. Some candidate materials have been tested in particle beams, and others seemed reasonable to analyze in this manner before deciding to test them. The two metal alloys analyzed are actual materials being designed into or used in aircraft and spacecraft today. This analysis shows that hydrogen-bearing materials have the best shielding characteristics over the metal alloys. It also shows that neutrons above 1 MeV are reflected out of the face of the slab better by larger quantities of carbon in the material. If a low-energy absorber is added to the material, fewer neutrons are transmitted through the material. Future analyses should focus on combinations of scatterers and absorbers to optimize these reaction channels and on the higher energy neutron component (above 50 MeV).

  14. Surface Coordination of Adatoms by Scanned Low Energy Photoelectron Diffraction

    NASA Astrophysics Data System (ADS)

    Asensio, M. C.

    In this article, a brief overview of the current activity in the field of low energy photoelectron diffraction is presented. Although alternatively angle and energy-scanned photoelectron diffraction can be used to obtain the surface-structural information, we limit our discussion to the low energy and energy-scanned modes and their use in connection with a new developed direct method. By the use of this most recent approach, adatom-substrate distances and adsorption sites are directly revealed from a discrete mapping of the Fourier transform of scanned energy photoelectron diffraction spectra, measured at a representative set of geometries, which depend on the symmetry of the particular studied system. In addition, a short discussion on the determination of the detailed structure of adsorbed overlayers by the traditional trial-and-error method is included, using model multiple scattering calculations. These latest developments are illustrated with a specific example of an atomic adsorbate, and comments about the capabilities and limitations of photoelectron diffraction as a structural technique in new fields.

  15. Low-energy electron-impact ionization of helium

    SciTech Connect

    Schow, E.; Hazlett, K.; Childers, J. G.; Medina, C.; Vitug, G.; Khakoo, M. A.; Bray, I.; Fursa, D. V.

    2005-12-15

    Normalized doubly differential cross sections for the electron-impact ionization of helium at low energies are presented. The data are taken at the incident electron energies of 26.3, 28.3, 30.3, 32.5, 34.3, 36.5, and 40.7 eV and for scattering angles of 10 deg. -130 deg. The measurements involve the use of the moveable target method developed at California State University Fullerton to accurately determine the continuum background in the energy-loss spectra. Normalization of experimental data is made on a relative scale to well-established experimental differential cross sections for excitation of the n=2 manifold of helium and then on an absolute scale to the well-established total ionization cross sections of Shah et al. [J. Phys. B 21, 2751 (1988)]. Comparisons are made with available experimental data and the results of the convergent close-coupling theory.

  16. Maximum Likelihood Analysis of Low Energy CDMS II Germanium Data

    SciTech Connect

    Agnese, R.

    2015-03-30

    We report on the results of a search for a Weakly Interacting Massive Particle (WIMP) signal in low-energy data of the Cryogenic Dark Matter Search experiment using a maximum likelihood analysis. A background model is constructed using GEANT4 to simulate the surface-event background from Pb210decay-chain events, while using independent calibration data to model the gamma background. Fitting this background model to the data results in no statistically significant WIMP component. In addition, we also perform fits using an analytic ad hoc background model proposed by Collar and Fields, who claimed to find a large excess of signal-like events in our data. Finally, we confirm the strong preference for a signal hypothesis in their analysis under these assumptions, but excesses are observed in both single- and multiple-scatter events, which implies the signal is not caused by WIMPs, but rather reflects the inadequacy of their background model.

  17. Maximum likelihood analysis of low energy CDMS II germanium data

    NASA Astrophysics Data System (ADS)

    Agnese, R.; Anderson, A. J.; Balakishiyeva, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Bowles, M. A.; Brandt, D.; Brink, P. L.; Bunker, R.; Cabrera, B.; Caldwell, D. O.; Cerdeno, D. G.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Fritts, M.; Godfrey, G. L.; Golwala, S. R.; Graham, M.; Hall, J.; Harris, H. R.; Hertel, S. A.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Kiveni, M.; Koch, K.; Leder, A.; Loer, B.; Lopez Asamar, E.; Mahapatra, R.; Mandic, V.; Martinez, C.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Moore, D. C.; Nelson, R. H.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Rogers, H. E.; Saab, T.; Sadoulet, B.; Sander, J.; Schneck, K.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wright, D. H.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.; SuperCDMS Collaboration

    2015-03-01

    We report on the results of a search for a Weakly Interacting Massive Particle (WIMP) signal in low-energy data of the Cryogenic Dark Matter Search experiment using a maximum likelihood analysis. A background model is constructed using geant4 to simulate the surface-event background from 210Pb decay-chain events, while using independent calibration data to model the gamma background. Fitting this background model to the data results in no statistically significant WIMP component. In addition, we perform fits using an analytic ad hoc background model proposed by Collar and Fields, who claimed to find a large excess of signal-like events in our data. We confirm the strong preference for a signal hypothesis in their analysis under these assumptions, but excesses are observed in both single- and multiple-scatter events, which implies the signal is not caused by WIMPs, but rather reflects the inadequacy of their background model.

  18. Low-energy dissociative electron attachment to CF2

    NASA Astrophysics Data System (ADS)

    Chourou, S. T.; Larson, Ã.; Orel, A. E.

    2015-08-01

    We present the results of a theoretical study of dissociative electron attachment (DEA) of low-energy electrons to CF2. We carried out electron scattering calculations using the complex Kohn variational method at the static-exchange and relaxed self-consistent field (SCF) level at the equilibrium geometry and compare our differential cross sections to other results. We then repeated these calculations as a function of the three internal degrees of freedom to obtain the resonance energy surfaces and autoionization widths. We use this data as input to form the Hamiltonian relevant to the nuclear dynamics. The multidimensional wave equation is solved using the multiconfiguration time-dependent Hartree (MCTDH) approach within the local approximation.

  19. Low energy vibrational excitations characteristic of superionic glass

    NASA Astrophysics Data System (ADS)

    Nakamura, M.; Iwase, H.; Arai, M.; Kartini, E.; Russina, M.; Yokoo, T.; Taylor, J. W.

    2006-11-01

    The mechanism of high ionic conductivity in superionic glass constitutes an unsolved problem in the field of science. Here we performed inelastic neutron scattering measurements of superionic glass system (AgI)x(Ag2S)x(AgPO3) by using MARI spectrometer at ISIS, and found that the Q-dependence of inelastic intensity in the energy region from 1 to 3 meV of superionic phase glass shows an excess intensity above Q=1.8 Å-1 compared with insulator phase. Similar phenomena were also observed in another superionic glass (AgI)0.5(AgPO3)0.5 by using NEAT spectrometer at HMI with high resolution measurement. These results clearly suggest peculiar low energy vibrational excitations should be universal features of superionic glass.

  20. Low energy ion loss at Mars

    NASA Astrophysics Data System (ADS)

    Curry, S.; Liemohn, M.; Fang, X.; Ma, Y.

    2012-04-01

    Current data observations and modeling efforts have indicated that the low-energy pick-up ions on Mars significantly contribute to the overall escape rate. Due to the lack of a dipole magnetic field, the solar wind directly interacts with the dayside upper atmosphere causing particles to be stripped away. In this study, we use a 3-D Monte Carlo test particle simulation with virtual detectors to observe low energy ions (< 50 eV) in the Mars space environment. We will present velocity space distributions that can capture the asymmetric and non-gyrotropic features of particle motion. The effect of different solar conditions will also be discussed with respect to ion fluxes at various spatial locations as well as overall loss in order to robustly describe the physical processes controlling the distribution of planetary ions and atmospheric escape.

  1. Low energy cyclotron for radiocarbon dating

    SciTech Connect

    Welch, J.J.

    1985-01-01

    The author built and tested a low energy cyclotron for radiocarbon dating similar to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity /sup 14/C measurements that are now done at accelerator facilities. The author found that no significant background is present when the cyclotron is tuned to accelerate /sup 14/C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect /sup 14/C directly at modern concentrations. The author shows how a conventional carbon negative ion source located outside the cyclotron magnet, would produce sufficient beam and provide for quick sample changing to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.

  2. Low Energy Transfer to the Moon

    NASA Astrophysics Data System (ADS)

    Koon, W. S.; Lo, M. W.; Marsden, J. E.; Ross, S. D.

    In 1991, the Japanese Hiten mission used a low energy transfer with a ballistic capture at the Moon which required less Δ V than a standard Hohmann transfer. In this paper, we apply the dynamical systems techniques developed in our earlier work to reproduce systematically a Hiten-like mission. We approximate the Sun-Earth-Moon-spacecraft 4-body system as two 3-body systems. Using the invariant manifold structures of the Lagrange points of the 3-body systems, we are able to construct low energy transfer trajectories from the Earth which execute ballistic capture at the Moon. The techniques used in the design and construction of this trajectory may be applied in many situations.

  3. PHYSICS WITH ULTRA-LOW ENERGY ANTIPROTONS

    SciTech Connect

    M. HOLZSCHEITER

    2001-02-01

    In this report the author describes the current status of the antiproton deceleration (AD) facility at CERN, and highlights the physics program with ultra-low energy antiproton at this installation. He also comments on future possibilities provided higher intensity antiproton beams become available at Fermilab, and review possibilities for initial experiments using direct degrading of high energy antiprotons in material has been developed and proven at CERN.

  4. Seesaw scale from low-energy parameters

    SciTech Connect

    He Xiaogang

    2012-07-27

    Seesaw models can provide explanations why neutrino are so much lighter than their charged partners. However, A priori, the seesaw scale is not determined. In this talk, I report work published in Ref.[1] by Law, Volkas and myself which shows that it is possible to construct theoretical models where the seesaw scale is completely determined in terms of low-energy fermion mass, mixing angles and CP-violating phases observable quantities.

  5. Targeting Low-Energy Ballistic Lunar Transfers

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.

    2010-01-01

    Numerous low-energy ballistic transfers exist between the Earth and Moon that require less fuel than conventional transfers, but require three or more months of transfer time. An entirely ballistic lunar transfer departs the Earth from a particular declination at some time in order to arrive at the Moon at a given time along a desirable approach. Maneuvers may be added to the trajectory in order to adjust the Earth departure to meet mission requirements. In this paper, we characterize the (Delta)V cost required to adjust a low-energy ballistic lunar transfer such that a spacecraft may depart the Earth at a desirable declination, e.g., 28.5(white bullet), on a designated date. This study identifies the optimal locations to place one or two maneuvers along a transfer to minimize the (Delta)V cost of the transfer. One practical application of this study is to characterize the launch period for a mission that aims to launch from a particular launch site, such as Cape Canaveral, Florida, and arrive at a particular orbit at the Moon on a given date using a three-month low-energy transfer.

  6. Low-energy electron interactions with biomolecules

    NASA Astrophysics Data System (ADS)

    Winstead, Carl

    2012-06-01

    Low-energy electron interactions with biomolecules have been the focus of sustained attention over the past decade. The demonstration by Sanche and coworkers that even subexcitation and subionization electrons can induce strand breaks in DNA opened a new frontier in understanding radiation damage to living systems. Many studies of DNA subunits and their analogues, both experimental and theoretical, have elucidated likely mechanisms by which slow electrons attach to and disrupt DNA, although the full picture is far from clear and some elements of it remain controversial. Increasing attention is also being given to low-energy electron collisions with amino acids in order to explore possible mechanisms of electron-mediated radiation damage to proteins. In a completely different context, electron-biomolecule collisions are fundamental to spark ignition and cumbustion of biofuels such as methanol and ethanol. Not to be overlooked, either, is the simplest but most ubiquitous biomolecule of all, water, whose low-energy electron cross sections remain surprisingly ill-characterized. This talk will survery recent ab initio computational studies using the Schwinger multichannel method of DNA- and protein-related molecules, alcohols, and water. Much of the work to be presented was carried out in collaboration with experimentalists who undertook complementary measurements, allowing for useful comparisons to be made. Although the primary focus will be on electronically elastic collisions relevant to dissociative attachment and electron transport, electron-impact excitation cross sections for water will be presented and discussed.

  7. Ab initio calculations on collisions of low energy electrons with polyatomic molecules

    SciTech Connect

    Rescigno, T.N.

    1991-08-01

    The Kohn variational method is one of simplest, and oldest, techniques for performing scattering calculations. Nevertheless, a number of formal problems, as well as practical difficulties associated with the computation of certain required matrix elements, delayed its application to electron--molecule scattering problems for many years. This paper will describe the recent theoretical and computational developments that have made the complex'' Kohn variational method a practical tool for carrying out calculations of low energy electron--molecule scattering. Recent calculations on a number of target molecules will also be summarized. 41 refs., 7 figs.

  8. Nonadiabatic couplings in low-energy collisions of hydrogen ground-state atoms

    SciTech Connect

    Wolniewicz, L.

    2003-10-01

    The effect of nonadiabatic couplings on low-energy s-wave scattering of two hydrogen atoms is investigated. Coupling matrix elements are computed in a wide range of internuclear distances. The resulting scattering equations are numerically unstable and therefore are integrated only approximately. Computations are performed for H, D, and T atoms. The phase shifts in the zero velocity limit are inversely proportional to the nuclear reduced mass {delta}{sub 0}{approx_equal}0.392/{mu}. This leads to infinite scattering lengths.

  9. RHIC low energy beam loss projections

    SciTech Connect

    Satogata,T.

    2009-08-01

    For RHIC low-energy operations, we plan to collide Au beams with energies of E = 2:5-10 GeV/u in RHIC. Beams are injected into collision optics, and RHIC runs as a storage ring with no acceleration. At these low energies, observed beam lifetimes are minutes, with measured beam lifetimes of 3.5 min (fast) and 50 min (slow) at E=4.6 GeV/u in the March 2008 test run. With these lifetimes we can operate RHIC as a storage ring to produce reasonable integrated luminosity. This note estimates beam losses and collimator/dump energy deposition in normal injection modes of low energy operation. The main question is whether a normal injection run is feasible for an FY10 10-15 week operations run from a radiation safety perspective. A peripheral question is whether continuous injection operations is feasible from a radiation safety perspective. In continuous injection mode, we fill both rings, then continuously extract and reinject the oldest bunches that have suffered the most beam loss to increase the overall integrated luminosity. We expect to gain a factor of 2-3 in integrated luminosity from continuous injection at lowest energies if implemented[1]. Continuous injection is feasible by FY11 from an engineering perspective given enough effort, but the required extra safety controls and hardware dose risk make it unappealing for the projected luminosity improvement. Low-energy electron cooling will reduce beam losses by at least an order of magnitude vs normal low-energy operations, but low energy cooling is only feasible in the FY13 timescale and therefore beyond the scope of this note. For normal injection low energy estimates we assume the following: (1) RHIC beam total energies are E=2.5-10 GeV/u. (Continuous injection mode is probably unnecessary above total energies of E=7-8 GeV/u.); (2) RHIC operates only as a storage ring, with no acceleration; (3) 110 bunches of about 0.5-1.0 x 10{sup 9} initial bunch intensities (50-100% injection efficiency, likely conservative

  10. Studies on Nuclear Astrophysics and Exotic Structure at the Low-Energy RI Beam Facility CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Kahl, D.; Hayakawa, S.; Sakaguchi, Y.; Nakao, T.; Wakabayashi, Y.; Hashimoto, T.; Teranishi, T.; Kubono, S.; Cherubini, S.; Mazzocco, M.; Signorini, C.; Gulino, M.; Di Pietro, A.; Figuera, P.; La Cognata, M.; Lattuada, M.; Spitaleri, C.; Torresi, D.; Lee, P. S.; Lee, C. S.; Komatsubara, T.; Iwasa, N.; Okoda, Y.; Pierroutsakou, D.; Parascandolo, C.; La Commara, M.; Strano, E.; Boiano, C.; Boiano, A.; Manea, C.; Sánchez-Benítez, A. M.; Miyatake, H.; Watanabe, Y. X.; Ishiyama, H.; Jeong, S. C.; Imai, N.; Hirayama, Y.; Kimura, S.; Mukai, M.; Kim, Y. H.; Lin, C. J.; Jia, H. M.; Yan, L.; Yang, Y. Y.; Kawabata, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. N.

    Studies on nuclear astrophysics, resonant structure, and nuclear reaction are going on at CRIB (CNS Radioactive Ion Beam separator), a low-energy RI beam separator operated by Center for Nuclear Study (CNS), the University of Tokyo. Two major methods used at CRIB to study nuclear reactions of astrophysical relevance are the resonant scattering, and direct measurements of (α,p) reactions using a thick-gas target. Several experiments for decay measurements and reaction mechanism are also performed using low-energy RI beams at CRIB. Some of the results from recent experiments at CRIB are discussed.

  11. Low-energy proton capture reactions

    SciTech Connect

    Lipoglavsek, M.; Cvetinovic, A.; Gajevic, J.; Likar, A.; Vavpetic, P.; Petrovic, T.

    2014-05-09

    An overview of experimental problems in measuring the cross sections for (p,γ) and (p,n) reactions at low energies is given with a specific emphasis on electron screening in metallic targets. Thick target γ-ray and neutron yields are compared for Ni and NiO targets, V and VO{sub 2} targets and Mn and MnO targets. The {sup 1}H({sup 7}Li,α){sup 4}He reaction was studied in inverse kinematics with hydrogen loaded into Pd and PdAg alloy foils from gas phase. Based on these results, a new approach to electron screening in nuclear reactions is suggested.

  12. Low energy fission: dynamics and scission configurations

    NASA Astrophysics Data System (ADS)

    Goutte, H.; Berger, J.-F.; Gogny, D.; Younes, W.

    2005-11-01

    In the first part of this paper we recall a recent study concerning low energy fission dynamics. Propagation is made by use of the Time Dependent Generator Coordinate Method, where the basis states are taken from self-consistent Hartree-Fock-Bogoliubov calculations with the Gogny force. Theoretical fragment mass distributions are presented and compared with the evaluation made by Wahl. In the second part of this paper, new results concerning scission configurations are shown. Deviations of the fission fragment proton numbers from the Unchanged Charge Distribution prescription and fission fragment deformations are discussed.

  13. FLSR - The Frankfurt low energy storage ring

    NASA Astrophysics Data System (ADS)

    Stiebing, K. E.; Alexandrov, V.; Dörner, R.; Enz, S.; Kazarinov, N. Yu.; Kruppi, T.; Schempp, A.; Schmidt Böcking, H.; Völp, M.; Ziel, P.; Dworak, M.; Dilfer, W.

    2010-02-01

    An electrostatic storage ring for low-energy ions with a design energy of 50 keV is presently being set up at the Institut für Kernphysik der Johann Wolfgang Goethe-Universität Frankfurt am Main, Germany (IKF). This new device will provide a basis for new experiments on the dynamics of ionic and molecular collisions, as well as for high precision and time resolved laser spectroscopy. In this article, the design parameters of this instrument are reported.

  14. The low energy booster project status

    SciTech Connect

    Tuttle, G.W.

    1993-05-01

    In order to achieve the required injection momentum, the Superconducting Super Collider (SSC) has an accelerator chain comprised of a Linear Accelerator and three synchrotrons. The Low Energy Booster (LEB) is the first synchrotron in this chain. The LEB project has made significant progress in the development of major subsystems and conventional construction. This paper briefly reviews the performance requirements of the LEB and describes significant achievements in each of the major subsystem areas. Highlighted among these achievements are the LEB foreign collaborations with the Budker Institute of Nuclear Physics (BINP) located in Novosibirsk, Russia.

  15. Low energy signatures of nonlocal field theories

    NASA Astrophysics Data System (ADS)

    Belenchia, Alessio; Benincasa, Dionigi M. T.; Martín-Martínez, Eduardo; Saravani, Mehdi

    2016-09-01

    The response of inertial particle detectors coupled to a scalar field satisfying nonlocal dynamics described by nonanalytic functions of the d'Alembertian operator □ is studied. We show that spontaneous emission processes of a low energy particle detector are very sensitive to high-energy nonlocality scales. This allows us to suggest a nuclear physics experiment (˜MeV energy scales) that outperforms the sensitivity of LHC experiments by many orders of magnitude. This may have implications for the falsifiability of theoretical proposals of quantum gravity.

  16. Low energy ion-molecule reaction dynamics and chemiionization kinetics

    NASA Astrophysics Data System (ADS)

    Farrar, J. M.

    Low energy crossed ion beam neutral beam studies of a wide spectrum of elementary chemical reactions were performed. The reactive scattering work embodies crossed beam studies of simple chemical processes under single collision conditions which elucidate reaction dynamics by measuring product branching ratios, translational energy distributions and scattering angle distributions. The studies have emphasized the proton transfer reactions of the important flame cations HCO(+) and H3O(+) with a number of neutral molecules present in flames, including H2O, CH3OH, CH3CH2OH, and (CH3)2CO, and a wide variety of reactions of the ground state carbon cation, C(+)((2)P), with neutrals, illustrating the important reactions of insertion into C-H, O-H, N-H, and C-C bonds, as well as condensation reactions in which new C-C bonds are formed, yielding significant increases in the molecular weight of the charged product. These studies represent the first crossed beam studies in which information more detailed than rate constants and energy dependent total cross sections was inferred about the reaction dynamics.

  17. The Telescope Array's Low Energy Extension: TALE

    NASA Astrophysics Data System (ADS)

    Matthews, John

    2009-05-01

    A great deal of information about the sources of ultra high energy cosmic rays exists encoded in the energy spectrum. There are three spectral features in the ultra high energy regime (the second knee, the ankle, and the GZK cut-off). An important composition change also occurs in this energy range. The Telescope Array (TA) is a large area ultra high energy cosmic ray observatory built and operated by groups from the US, Japan, Korea, and Russia. The existing part of the Telescope Array already has good efficiency above the ankle (˜10^18.5 eV). These detectors are already in the field collecting data. The TA Low Energy Extension (TALE) refers to the detectors devoted to the ``low energy'' portion of the spectrum - 10^16.5 - 10^19 eV. The aim of TA/TALE is to understand the origin of cosmic rays and to study their composition over a broad energy range. We will introduce the detector components and discuss the opportunities.

  18. Low Energy Ion-Molecule Reactions

    SciTech Connect

    James M. Farrar

    2004-05-01

    This objective of this project is to study the dynamics of the interactions of low energy ions important in combustion with small molecules in the gas phase and with liquid hydrocarbon surfaces. The first of these topics is a long-standing project in our laboratory devoted to probing the key features of potential energy surfaces that control chemical reactivity. The project provides detailed information on the utilization of specific forms of incident energy, the role of preferred reagent geometries, and the disposal of total reaction energy into product degrees of freedom. We employ crossed molecular beam methods under single collision conditions, at collision energies from below one eV to several eV, to probe potential surfaces over a broad range of distances and interaction energies. These studies allow us to test and validate dynamical models describing chemical reactivity. Measurements of energy and angular distributions of the reaction products with vibrational state resolution provide the key data for these studies. We employ the crossed beam low energy mass spectrometry methods that we have developed over the last several years.

  19. Low Energy Nuclear Reactions: 2007 Update

    NASA Astrophysics Data System (ADS)

    Krivit, Steven B.

    2007-03-01

    This paper presents an overview of low energy nuclear reactions, a subset of the field of condensed matter nuclear science. Condensed matter nuclear science studies nuclear effects in and/or on condensed matter, including low energy nuclear reactions, an entirely new branch of science that gained widespread attention and notoriety beginning in 1989 with the announcement of a previously unrecognized source of energy by Martin Fleischmann and Stanley Pons that came to be known as cold fusion. Two branches of LENR are recognized. The first includes a set of reactions like those observed by Fleischmann and Pons that use palladium and deuterium and yield excess heat and helium-4. Numerous mechanisms have been proposed to explain these reactions, however there is no consensus for, or general acceptance of, any of the theories. The claim of fusion is still considered speculative and, as such, is not an ideal term for this work. The other branch is a wide assortment of nuclear reactions that may occur with either hydrogen or deuterium. Anomalous nuclear transmutations are reported that involve light as well as heavy elements. The significant questions that face this field of research are: 1) Are LENRs a genuine nuclear reaction? 2) If so, is there a release of excess energy? 3) If there is, is the energy release cost-effective?

  20. Performance monitoring of low energy house, Macclesfield

    NASA Astrophysics Data System (ADS)

    Stephen, F. R.

    1980-01-01

    The monitoring of the energy balance of a very well insulated low-energy house in Macclesfield, England is discussed. The house is an existing dwelling which had been converted into a low-energy-requiring house by the reduction of heat loss through a high level of thermal insulation and the collection of solar energy by a water cascade solar panel with warm water storage. Measurements of house temperatures, radiation, off-peak electricity consumption and hot water and heating using were performed from January to August, 1978 and reveal that the house used less than 22,000 kWh electricity during that period, compared to 55,000 kWh expected if the house had been constructed to average insulation levels. Solar energy is found to contribute only 2% of house energy requirements, with the use of a heat pump combined with the solar panel leading to greater efficiency and thus utilization. In addition, the large thermal mass and good insulation are found to improve comfort by reducing temperature fluctuations, and the ventilation and low-temperature water return system employed provided satisfactory results.

  1. Low energy cyclotron for radiocarbon dating

    SciTech Connect

    Welch, J.J.

    1984-12-01

    The measurement of naturally occurring radioisotopes whose half lives are less than a few hundred million years but more than a few years provides information about the temporal behavior of geologic and climatic processes, the temporal history of meteoritic bodies as well as the production mechanisms of these radioisotopes. A new extremely sensitive technique for measuring these radioisotopes at tandem Van de Graaff and cyclotron facilities has been very successful though the high cost and limited availability have been discouraging. We have built and tested a low energy cyclotron for radiocarbon dating similar in size to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity /sup 14/C measurements that are now done at accelerator facilities. We found that no significant background is present when the cyclotron is tuned to accelerate /sup 14/C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect /sup 14/C directly at modern concentrations. We show how a conventional carbon negative ion source, located outside the cyclotron magnet, would produce sufficient beam and provide for quick sampling to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.

  2. Low Energy Antiproton Experiments - A Review

    SciTech Connect

    Jungmann, Klaus P.

    2005-10-19

    Low energy antiprotons offer excellent opportunities to study properties of fundamental forces and symmetries in nature. Experiments with them can contribute substantially to deepen our fundamental knowledge in atomic, nuclear and particle physics. Searches for new interactions can be carried out by studying discrete symmetries. Known interactions can be tested precisely and fundamental constants can be extracted from accurate measurements on free antiprotons (p-bar's) and bound two- and three-body systems such as antihydrogen (H-bar = p-bare-), the antprotonic helium ion (He++p-bar)+ and the antiprotonic atomcule (He++p-bare-) . The trapping of a single p-bar in a Penning trap, the formation and precise studies of antiprotonic helium ions and atoms and recently the production of H-bar have been among the pioneering experiments. They have led already to precise values for p-bar parameters, accurate tests of bound two- and three-body Quantum Electrodynamics (QED), tests of the CPT theorem and a better understanding of atom formation from their constituents. Future experiments promise more precise tests of the standard theory and have a robust potential to discover new physics. Precision experiments with low energy p-bar's share the need for intense particle sources and the need for time to develop novel instrumentation with all other experiments, which aim for high precision in exotic fundamental systems. The experimental programs - carried out in the past mostly at the former LEAR facility and at present at the AD facility at CERN - would benefit from intense future sources of low energy p-bar's. The highest possible p-bar fluxes should be aimed for at new facilities such as the planned FLAIR facility at GSI in order to maximize the potential of delicate precision experiments to influence model building. Examples of key p-bar experiments are discussed here and compared with other experiments in the field. Among the central issues is their potential to obtain

  3. Phenomenological implications of low energy supersymmetry breaking

    SciTech Connect

    Dimopoulos, S. |; Dine, M.; Raby, S.; Thomas, S.; Wells, J.D.

    1996-07-01

    The experimental signatures for low energy supersymmetry breaking are presented. The lightest standard model superpartner is unstable and decays to its partner plus a Goldstino, G. For a supersymmetry breaking scale below a few 1,000 TeV this decay can take place within a detector, leading to very distinctive signatures. If a neutralino is the lightest standard model superpartner it decays by {chi}{sub 1}{sup 0} {r_arrow} {gamma} + G, and if kinematically accessible by {chi}{sub 1}{sup 0} {r_arrow} (Z{sup 0}, h{sup 0}, H{sup 0}, A{sup 0}) + G. These decays can give rise to displaced vertices. Alternately, if a slepton is the lightest standard model superpartner it decays by {tilde l} {r_arrow} l + G. This can be seen as a greater than minimum ionizing charged particle track, possibly with a kink to a minimum ionizing track.

  4. Low energy ion-molecule reactions

    SciTech Connect

    Farrar, J.M.

    1993-12-01

    This project is concerned with elucidating the dynamics of elementary ion-molecule reactions at collision energies near and below 1 eV. From measurements of the angular and energy distributions of the reaction products, one can infer intimathe details about the nature of collisions leading to chemical reaction, the geometries and lifetimes of intermediate complexes that govern the reaction dynamics, and the collision energy dependence of these dynamical features. The author employs crossed-beam low energy mass spectrometry technology developed over the last several years, with the focus of current research on proton transfer and hydrogen atom transfer reactions of te O{sup {minus}} ion with species such as HF, H{sub 2}O, and NH{sub 3}.

  5. Low energy high pressure miniature screw valve

    DOEpatents

    Fischer, Gary J.; Spletzer, Barry L.

    2006-12-12

    A low energy high pressure screw valve having a valve body having an upper portion and a lower portion, said lower portion of said valve body defining an inlet flow passage and an outlet flow passage traversing said valve body to a valve seat, said upper portion of said valve body defining a cavity at said valve seat, a diaphragm restricting flow between said upper portion of said valve body and said lower portion, said diaphragm capable of engaging said valve seat to restrict fluid communication between said inlet passage and said outlet passage, a plunger within said cavity supporting said diaphragm, said plunger being capable of engaging said diaphragm with said valve seat at said inlet and outlet fluid passages, said plunger being in point contact with a drive screw having threads engaged with opposing threads within said upper portion of said valve body such engagement allowing motion of said drive screw within said valve body.

  6. Low-energy irradiation effects in cellulose

    SciTech Connect

    Polvi, Jussi; Nordlund, Kai

    2014-01-14

    Using molecular dynamics simulations, we determined the threshold energy for creating defects as a function of the incident angle for all carbon and oxygen atoms in the cellulose monomer. Our analysis shows that the damage threshold energy is strongly dependent on the initial recoil direction and on average slightly higher for oxygen atoms than for carbon atoms in cellulose chain. We also performed cumulative bombardment simulations mimicking low-energy electron irradiation (such as TEM imaging) on cellulose. Analyzing the results, we found that formation of free molecules and broken glucose rings were the most common forms of damage, whereas cross-linking and chain scission were less common. Pre-existing damage was found to increase the probability of cross-linking.

  7. Low-energy neutral-atom spectrometer

    SciTech Connect

    Voss, D.E.; Cohen, S.A.

    1982-04-01

    The design, calibration, and performance of a low energy neutral atom spectrometer are described. Time-of-flight analysis is used to measure the energy spectrum of charge-exchange deuterium atoms emitted from the PLT tokamak plasma in the energy range from 20 to 1000 eV. The neutral outflux is gated on a 1 ..mu..sec time scale by a slotted rotating chopper disc, supported against gravity in vacuum by magnetic levitation, and is detected by secondary electron emission from a Cu-Be plate. The energy dependent detection efficiency has been measured in particle beam experiments and on the tokamak so that the diagnostic is absolutely calibrated, allowing quantitative particle fluxes to be determined with 200 ..mu..sec time resolution. In addition to its present application as a plasma diagnostic, the instrument is capable of making a wide variety of measurements relevant to atomic and surface physics.

  8. RHIC low energy tests and initial operations

    SciTech Connect

    Satogata,T.; Ahrens, L.; Bai, M.; Brennan, J.M.; Bruno, D.; Butler, J.; Drees, A.; Fedotov, A.; Fischer, W.; Harvey, M.; Hayes, T.; Jappe, W.; Lee, R.C.; Mackay, W.W.; Malitsky, N.; Marr, G.; Michnoff, R.; Oerter, B.; Pozdeyev, E.; Roser, T.; Severino, F.; Smith, K.; Tepikian, S.; Tsoupas, N.

    2009-05-04

    Future Relativistic Heavy Ion Collider (RHIC) runs, including a portion of FY10 heavy ion operations, will explore collisions at center of mass energies of 5-50 GeV/n (GeV/nucleon). Operations at these energies is motivated by a search for the QCD phase transition critical point. The lowest end of this energy range is nearly a factor of four below the nominal RHIC injection center of mass energy of {radical} s = 20.8 GeV/n. There are several operational challenges in the RHIC low-energy regime, including harmonic number changes, small longitudinal acceptance, lowered magnet field quality, nonlinear orbit control, and luminosity monitoring. We report on the experience with some of these challenges during beam tests with gold in March 2008, including first RHIC operations at {radical}s = 9.18 GeV/n and first beam experience at {radical}s = 5 GeV/n.

  9. Detection of low energy antimatter with emulsions

    NASA Astrophysics Data System (ADS)

    Aghion, S.; Ariga, A.; Ariga, T.; Bollani, M.; Dei Cas, E.; Ereditato, A.; Evans, C.; Ferragut, R.; Giammarchi, M.; Pistillo, C.; Romé, M.; Sala, S.; Scampoli, P.

    2016-06-01

    Emulsion detectors feature a very high position resolution and consequently represent an ideal device when particle detection is required at the micrometric scale. This is the case of quantum interferometry studies with antimatter, where micrometric fringes have to be measured. In this framework, we designed and realized a new emulsion based detector characterized by a gel enriched in terms of silver bromide crystal contents poured on a glass plate. We tested the sensitivity of such a detector to low energy positrons in the range 10–20 keV . The obtained results prove that nuclear emulsions are highly efficient at detecting positrons at these energies. This achievement paves the way to perform matter-wave interferometry with positrons using this technology.

  10. Low energy consumption spintronics using multiferroic heterostructures.

    PubMed

    Trassin, Morgan

    2016-01-27

    We review the recent progress in the field of multiferroic magnetoelectric heterostructures. The lack of single phase multiferroic candidates exhibiting simultaneously strong and coupled magnetic and ferroelectric orders led to an increased effort into the development of artificial multiferroic heterostructures in which these orders are combined by assembling different materials. The magnetoelectric coupling emerging from the created interface between the ferroelectric and ferromagnetic layers can result in electrically tunable magnetic transition temperature, magnetic anisotropy or magnetization reversal. The full potential of low energy consumption magnetic based devices for spintronics lies in our understanding of the magnetoelectric coupling at the scale of the ferroic domains. Although the thin film synthesis progresses resulted into the complete control of ferroic domain ordering using epitaxial strain, the local observation of magnetoelectric coupling remains challenging. The ability to imprint ferroelectric domains into ferromagnets and to manipulate those solely using electric fields suggests new technological advances for spintronics such as magnetoelectric memories or memristors.

  11. The Superconducting Super Collider Low Energy Booster

    SciTech Connect

    York, R.C.; Funk, W.; Garren, A.; Machida, S.; Mahale, N.K.; Peterson, J.; Pilat, F.; Wu, X. ); Wienands, U. )

    1991-05-01

    In collider fill mode, the Low Energy Booster (LEB) will accelerate 10{sup 12} protons in 114 bunches from an injection momentum of 1.22 GeV/c to a final momentum of 12 Gev/c, cycling at a frequency of 10 Hz. The most significant extension of present fast-cycling synchrotron technology arises from the requirement that the normalized transverse emittance (rms) of the beam be {le}0.6 {pi} {mu}m. In an alternative mode, the LEB will accelerate five times this current with a normalized transverse emittance {le} 4 {pi} {mu}m. A general overview of the design is presented. 7 refs., 2 figs., 4 tabs.

  12. Low energy AMS of americium and curium

    NASA Astrophysics Data System (ADS)

    Christl, Marcus; Dai, Xiongxin; Lachner, Johannes; Kramer-Tremblay, Sheila; Synal, Hans-Arno

    2014-07-01

    Accelerator mass spectrometry (AMS) has evolved over the past years as one of the most sensitive, selective, and robust techniques for actinide analyses. While analyses of U and Pu isotopes have already become routine at the ETH Zurich 0.5 MV AMS system "Tandy", there is an increasing demand for highly sensitive analyses of the higher actinides such as Am and Cm for bioassay applications and beyond. In order to extend the actinide capabilities of the compact ETH Zurich AMS system and to develop new, more sensitive bioassay routines, a pilot study was carried out. The aim was to investigate and document the performance and the potential background of Am and Cm analyses with low energy AMS. Our results show that 241Am and Cm isotopes can be determined relative to a 243Am tracer if samples and AMS standards are prepared identically with regard to the matrix elements, in which the sample is dispersed. In this first test, detection limits for Cm and Am isotopes are all in the sub-femtogram range and even below 100 ag for Cm isotopes. In a systematic background study in the mass range of the Cm isotopes, two formerly unknown metastable triply charged Th molecules were found on amu(244) and amu(248). The presence of such a background is not a principal problem for AMS if the stripper pressure is increased accordingly. Based on our first results, we conclude that ultra-trace analyses of Am and Cm isotopes for bioassay are very well possible with low energy AMS.

  13. Low energy demonstration accelerator technical area 53

    SciTech Connect

    1996-04-01

    As part of the Department of Energy`s (DOE) need to maintain the capability of producing tritium in support of its historic and near-term stewardship of the nation`s nuclear weapons stockpile, the agency has recently completed a Programmatic Environmental Impact Statement for Tritium Supply and Recycling. The resulting Record of Decision (ROD) determined that over the next three years the DOE would follow a dual-track acquisition strategy that assures tritium production for the nuclear weapon stockpile in a rapid, cost effective, and safe manner. Under this strategy the DOE will further investigate and compare two options for producing tritium: (1) purchase of an existing commercial light-water reactor or irradiation services with an option to purchase the reactor for conversion to a defense facility; and (2) design, build, and test critical components of a system for accelerator production of tritium (APT). The final decision to select the primary production option will be made by the Secretary of Energy in the October 1998 time frame. The alternative not chosen as the primary production method, if feasible, would be developed as a back-up tritium supply source. This Environmental Assessment (EA) analyzes the potential environmental effects that would be expected to occur if the DOE were to design, build, and test critical prototypical components of the accelerator system for tritium production, specifically the front-end low-energy section of the accelerator, at Los Alamos National Laboratory. The Low Energy Demonstration Accelerator (LEDA) would be incrementally developed and tested in five separate stages over the next seven years. The following issues were evaluated for the proposed action: utility demands, air, human health, environmental restoration, waste management, transportation, water, threatened and endangered species, wetlands, cultural resources, and environmental justice.

  14. The Low Energy Effective Area of the Chandra Low Energy Transmission Grating Spectrograph

    NASA Technical Reports Server (NTRS)

    Pease, D.; Drake, J. J.; Johnson, C. O.; Kashya, V.; Ratzlaff, P. W.; Wargelin, B. J.; Brinkman, A. C.; Kaastra, J. S.; vanderMeer, R.; Paerels, F. B.

    2000-01-01

    The Chandra X-ray Observatory was successfully launched on July 23, 1999, and subsequently began an intensive calibration phase. We present the preliminary results from the in-flight calibration of the low energy response of the High Resolution Camera spectroscopic readout (HRC-S) combined with the Low Energy Transmission Grating (LETG) aboard Chandra. These instruments comprise the Low Energy Transmission Grating Spectrograph (LETGS). For this calibration study, we employ a pure hydrogen non-LTE white dwarf emission model (T = 25000 K and log g = 9.0) for comparison with the Chandra observations of Sirius B. The pre-flight calibration of the LETGS effective area only covered wavelengths shortward of 44 A (E less than 277 eV). Our Sirius B analysis shows that the HRC-S quantum efficiency (QE) model assumed for longer wavelengths leads to an overestimate of the effective area by an average factor of about 1.6. We derive a correction to the low energy HRC-S QE model to match the predicted and observed Sirius B spectra over the wavelength range of 44-185 A. We make an independent test of our results by the comparison of a Chandra LETGS observation of HZ 43 with pure hydrogen model atmosphere predictions and find good agreement.

  15. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  16. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  17. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  18. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  19. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  20. Nucleon Spin Structure at Low Energies

    SciTech Connect

    Krebs, H.; Bernard, V.; Meissner, Ulf-G.

    2009-07-27

    We apply chiral effective field theory with explicit DELTA-1232) degrees of freedom to study double virtual Compton scattering at the photon point. Generalized spin polarizabilities are calculated up to order epsilon{sup 3} in the covariant small scale expansion. Systematic inclusion of DELTA degrees of freedom drastically improves the theoretical predictions.

  1. Study on astrophysical reactions using low-energy RI beams

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hidetoshi

    2009-10-01

    In recent years, low-energy RI beams can be produced in a good intensity and they have been used for studying many astrophysical reactions. One of the facilities producing low-energy RI beams is CRIB (CNS Radio-Isotope Beam separator) [1,2], an RI-beam separator of Center for Nuclear Study, University of Tokyo. Taking CRIB as an example, recent improvements on the RI-beam production and experimental results on astrophysical studies are presented. Several experimental approaches have been taken for the studies on astrophysical reactions.The feature of each method are discussed based on real measurements performed at CRIB. One is the direct method, applied for measurements of reactions such as (α,p) [3]. Another is the measurement of proton/alpha resonance scattering using the thick target method in inverse kinematics, by which we can obtain information on the resonances relevant in astrophysical reactions [4,5]. A recent fruitful result was from a measurement of proton resonance scattering using a ^7Be beam [5]. The energy level structure of ^8B, revealed by the experiment, is especially of interest as it is related with the ^7Be(p,γ) ^8B reaction, responsible for the production of ^8B neutrinos in the sun. We successfully determined parameters of resonances in ^8B below 6.7 MeV, which may affect the ^7Be(p,γ)^8B reaction rate at the solar temparature. Indirect methods, such as ANC and the Trojan Horse Method, were also used in some of the measurements.[4pt] [1] S. Kubono et al., Eur. Phys. J. A13 (2002) 217.[0pt] [2] Y. Yanagisawa et al., Nucl. Instrum. Meth. Phys. Res., Sect. A 539 (2005) 74.[0pt] [3] M. Notani et al., Nucl. Phys. A 764 (2004) 113c.[0pt] [4] T. Teranishi et al., Phys. Lett. B 650 (2007) 129.[0pt] [5] H. Yamaguchi et al., Phys. Lett. B 672 (2009) 230.

  2. Experimental studies using a low-energy RI beam separator at CNS

    NASA Astrophysics Data System (ADS)

    Teranishi, T.; Kubono, S.; Shimoura, S.; Notani, M.; Yanagisawa, Y.; Michimasa, S.; Ue, K.; Iwasaki, H.; Kurokawa, M.; Satou, Y.; Morikawa, T.; Saito, A.; Baba, H.; Lee, J. H.; Lee, C. S.; Fülöp, Zs.; Kato, S.

    2003-05-01

    Radioactive-ion (RI) beams of 10C, 14O, 12N and 11C with energies low 10 A MeV were produced by using a low-energy in-flight RI beam separator newly constructed by CNS, University of Tokyo. Using the 12N and 11C beams, some resonance states were identified in the proton elastic scattering 12N+p and 11C+p, respectively.

  3. Modification of polymer (PET) surface reactivity by low energy ion bombardment

    NASA Astrophysics Data System (ADS)

    Bertrand, P.; De Puydt, Y.; Beuken, J.-M.; Lutgen, P.; Feyder, G.

    The surface of polyethylene terephtalate (PET) was studied by low energy He + ion scattering (ISS). Modifications of the surface composition induced by the He + and Ar + bombardments are observed. The ion bombardment causes surface damages with bond breaking and it results a highly activated surface for the chemisorption of nitrogen from the residual gas phase. Similar effects were observed on highly oriented pyrolytic graphite when analyzed in the same beam conditions.

  4. Alpha-induced reaction studies using low-energy RI beams at CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Kahl, D.; Hu, J.; Kubono, S.; Hayakawa, S.; Hashimoto, T.

    2012-11-01

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Studies on proton and alpha resonance scatterings, (α, p) reactions, and other types of measurements (β-decay lifetimes etc.) have been performed using RI beams at CRIB, motivated by interests on astrophysical reactions and exotic nuclear structure. Among the studies at CRIB, the measurement of 7Li+α/7Be+α resonant scatterings are presented.

  5. Alpha-induced reaction studies using low-energy RI beams at CRIB

    SciTech Connect

    Yamaguchi, H.; Kahl, D.; Hu, J.; Kubono, S.; Hayakawa, S.; Hashimoto, T.

    2012-11-12

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Studies on proton and alpha resonance scatterings, ({alpha}, p) reactions, and other types of measurements ({beta}-decay lifetimes etc.) have been performed using RI beams at CRIB, motivated by interests on astrophysical reactions and exotic nuclear structure. Among the studies at CRIB, the measurement of {sup 7}Li+{alpha}/{sup 7}Be+{alpha} resonant scatterings are presented.

  6. Coherent scattering of cosmic neutrinos

    NASA Technical Reports Server (NTRS)

    Opher, R.

    1974-01-01

    It is shown that cosmic neutrino scattering can be non-negligible when coherence effects previously neglected are taken into account. The coherent neutrino scattering cross section is derived and the neutrino index of refraction evaluated. As an example of coherent neutrino scattering, a detector using critical reflection is described which in principle can detect the low energy cosmic neutrino background allowed by the measured cosmological red shift.

  7. Studies in Low-Energy Nuclear Science

    SciTech Connect

    Brune, Carl R; Grimes, Steven M

    2006-03-30

    This report presents a summary of research projects in the area of low energy nuclear reactions and structure, carried out between 1 January 2003 and 31 December 2005 and supported by U.S. DOE grant number DE-FG03-03NA00074. Cross sections measured with high resolution have been subjected to an Ericson theory analysis to infer information about the nuclear level density. Other measurements were made of the spectral shape of particles produced in evaporation processes; these also yield level density information. A major project was the development of a new Hauser-Feshbach code for analyzing such spectra. Other measurements produced information on the spectra of gamma rays emitted in reactions on heavy nuclei and gave a means of refining our understanding of gamma-ray strength functions. Finally,reactions on light nuclei were studied and subjected to an R-matrix analysis. Cross sections fora network of nuclear reactions proceedingthrough a given compound nucleus shouldgreatly constrain the family of allowed parameters. Modifications to the formalism andcomputer code are also discussed.

  8. Low energy stable plasma calibration facility.

    PubMed

    Frederick-Frost, K M; Lynch, K A

    2007-07-01

    We have designed and fabricated a low energy plasma calibration facility for testing and calibration of rocket-borne charged-particle detectors and for the investigation of plasma sheath formation in an environment with ionospheric plasma energies, densities, and Debye lengths. We describe the vacuum system and associated plasma source, which was modified from a Naval Research Laboratory design [Bowles et al. Rev. Sci. Instrum. 67, 455 (1996)]. Mechanical and electrical modifications to this cylindrical microwave resonant source are outlined together with a different method of operating the magnetron that achieves a stable discharge. This facility produces unmagnetized plasmas with densities from 1x10(3)/cm(3) to 6x10(5)/cm(3), electron temperatures from 0.1 to 1.7 eV, and plasma potentials from 0.5 to 8 V depending on varying input microwave power and neutral gas flow. For the range of input microwave power explored (350-600 W), the energy density of the plasma remains constant because of an inverse relationship between density and temperature. This relationship allows a wide range of Debye lengths (0.3-8.4 cm) to be investigated, which is ideal for simulating the ionospheric plasma sheaths we explore.

  9. Low energy CMOS for space applications

    NASA Technical Reports Server (NTRS)

    Panwar, Ramesh; Alkalaj, Leon

    1992-01-01

    The current focus of NASA's space flight programs reflects a new thrust towards smaller, less costly, and more frequent space missions, when compared to missions such as Galileo, Magellan, or Cassini. Recently, the concept of a microspacecraft was proposed. In this concept, a small, compact spacecraft that weighs tens of kilograms performs focused scientific objectives such as imaging. Similarly, a Mars Lander micro-rover project is under study that will allow miniature robots weighing less than seven kilograms to explore the Martian surface. To bring the microspacecraft and microrover ideas to fruition, one will have to leverage compact 3D multi-chip module-based multiprocessors (MCM) technologies. Low energy CMOS will become increasingly important because of the thermodynamic considerations in cooling compact 3D MCM implementations and also from considerations of the power budget for space applications. In this paper, we show how the operating voltage is related to the threshold voltage of the CMOS transistors for accomplishing a task in VLSI with minimal energy. We also derive expressions for the noise margins at the optimal operating point. We then look at a low voltage CMOS (LVCMOS) technology developed at Stanford University which improves the power consumption over conventional CMOS by a couple of orders of magnitude and consider the suitability of the technology for space applications by characterizing its SEU immunity.

  10. Oscillations of very low energy atmospheric neutrinos

    SciTech Connect

    Peres, Orlando L. G.; Smirnov, A. Yu.

    2009-06-01

    There are several new features in the production, oscillations, and detection of the atmospheric neutrinos of low energies E < or approx. 100 MeV. The flavor ratio r of muon to electron neutrino fluxes is substantially smaller than 2 and decreases with energy, a significant part of events is due to the decay of invisible muons at rest, etc. Oscillations in a two-layer medium (atmosphere-Earth) should be taken into account. We derive analytical and semianalytical expressions for the oscillation probabilities of these 'sub-sub-GeV' neutrinos. The energy spectra of the e-like events in water Cherenkov detectors are computed, and the dependence of the spectra on the 2-3 mixing angle {theta}{sub 23}, the 1-3 mixing, and the CP-violation phase are studied. We find that variations of {theta}{sub 23} in the presently allowed region change the number of e-like events by about 15%-20% as well as lead to distortion of the energy spectrum. The 1-3 mixing and CP violation can lead to {approx}10% effects. Detailed study of the sub-sub-GeV neutrinos will be possible in future megaton-scale detectors.

  11. Low energy beam transport system developments

    NASA Astrophysics Data System (ADS)

    Dudnikov, V.; Han, B.; Stockli, M.; Welton, R.; Dudnikova, G.

    2015-04-01

    For high brightness beam production it is important to preserve the brightness in the low energy beam transport system (LEBT) used to transport and match the ion beams to the next stage of acceleration, usually an RFQ. While electrostatic focusing can be problematic for high current beam transport, reliable electrostatic LEBT operation has been demonstrated with H- beams up to 60 mA. Now, however, it is commonly accepted that an optimal LEBT for high current accelerator applications consists of focusing solenoids with space charge compensation. Two-solenoid LEBTs are successfully used for high current (>100 mA) proton beam transport. Preservation of low emittances (~0.15 π mm-mrad) requires the addition of a heavy gas (Xe, Kr), which causes ~5% of proton loss in a 1 m long LEBT. Similar Xe densities would be required to preserve low emittances of H- beams, but such gas densities cause unacceptably high H- beam losses. A short LEBT with only one short solenoid, movable for RFQ matching, can be used for reduced negative ion stripping. A strong electrostatic-focusing LEBT has been successfully adopted for transport of high current H- beams in the SNS Front End. Some modifications of such electrostatic LEBTs are expected to improve the reliable transport of intense positive and negative ion beams without greatly degrading their low emittances. We concentrate on processes that determine the beam brightness degradation and on their prevention. Proposed improvements to the SNS electrostatic LEBT are discussed.

  12. Optimal Low Energy Earth-Moon Transfers

    NASA Technical Reports Server (NTRS)

    Griesemer, Paul Ricord; Ocampo, Cesar; Cooley, D. S.

    2010-01-01

    The optimality of a low-energy Earth-Moon transfer is examined for the first time using primer vector theory. An optimal control problem is formed with the following free variables: the location, time, and magnitude of the transfer insertion burn, and the transfer time. A constraint is placed on the initial state of the spacecraft to bind it to a given initial orbit around a first body, and on the final state of the spacecraft to limit its Keplerian energy with respect to a second body. Optimal transfers in the system are shown to meet certain conditions placed on the primer vector and its time derivative. A two point boundary value problem containing these necessary conditions is created for use in targeting optimal transfers. The two point boundary value problem is then applied to the ballistic lunar capture problem, and an optimal trajectory is shown. Additionally, the ballistic lunar capture trajectory is examined to determine whether one or more additional impulses may improve on the cost of the transfer.

  13. RHIC low-energy challenges and plans

    SciTech Connect

    Satogata,T.; Ahrens, L.; Bai, M.; Brennan, J.M.; Bruno, D.; Butler, J.; Drees, A.; Fedotov, A.; Fischer, W.; Harvey, M.; Hayes, T.; Jappe, W.; Lee, R.C.; MacKay, W.W.; Malitsky, N.; Marr, G.; Michnoff, R.; Oerter, B.; Pozdeyev, E.; Roser, T.; Schoefer, V.; Severino, F.; Smith, K.; Tepikian, S.; Tsoupas, N.

    2009-06-08

    Future Relativistic Heavy Ion Collider (RHIC) runs, including a portion of FY10 heavy ion operations, will explore collisions at center of mass energies of 5-50 GeV/n (GeV/nucleon). Operations at these energies is motivated by the search for a possible QCD phase transition critical point. The lowest end of this energy range is nearly a factor of four below the nominal RHIC injection center of mass energy {radical}s = 19.6 GeV/n. There are several operational challenges in the RHIC low-energy regime, including harmonic number changes, small longitudinal acceptance, lowered magnet field quality, nonlinear orbit control, and luminosity monitoring. We report on the experience with these challenges during beam tests with gold beams in March 2008. This includes first operations at {radical}s = 9.18 GeV/n, first beam experience at {radical}s = 5 GeV/n, and luminosity projections for near-term operations.

  14. Low Energy Transfer to the Moon

    NASA Astrophysics Data System (ADS)

    Koon, W. S.; Lo, M. W.; Marsden, J. E.; Ross, S. D.

    2001-11-01

    New space missions are increasingly more complex; demand for exotic orbits to solve engineering problems has grown beyond the existing astrodynamic infrastructure based on two-body interactions. The delicate heteroclinic dynamics used by the Genesis Mission dramatically illustrate the need for a new paradigm: dynamical system study of three-body problem. Furthermore, this dynamics has much to say about the morphology and transport of materials within the Solar System. The cross-fertilization of ideas between the natural dynamics of the Solar System and applications to engineering has produced new techniques for constructing spacecraft trajectories with interesting characteristics. Specifically, these techniques are used here to produce a lunar capture mission which uses less fuel than a Hohmann transfer. We approximate the Sun-Earth-Moon-Spacecraft four-body problem as two three-body problems. Using the invariant manifold structures of the Lagrange points of the three-body systems, we are able to construct low energy transfer trajectories from the Earth which exhibit ballistic capture at the Moon. The techniques used in the design and construction of this trajectory may be applied in many situations. This is joint work with Martin W. Lo, Jerrold E. Marsden and Shane D. Ross and was partially supported by the National Science Foundation Grant No. KFI/ATM-9873133 under a contract with the Jet Propulsion Laboratory, NASA.

  15. New Cooperative Mechanisms of Low-Energy Nuclear Reactions Using Super Low-Energy External Field

    NASA Astrophysics Data System (ADS)

    Gareev, F. A.; Zhidkova, I. E.

    We propose a new mechanism of LENR: cooperative processes in the whole system, nuclei + atoms + condensed matter, can occur at a smaller threshold energies than the corresponding ones on free constituents. The cooperative processes can be induced and enhanced by low-energy external fields. The excess heat is the emission of internal energy and transmutations at LENR are the result of redistribution of inner energy of the whole system.

  16. Collisions of low-energy electrons with cyclohexane.

    PubMed

    Barbosa, Alessandra Souza; Bettega, Márcio H F

    2014-12-28

    We report calculated cross sections for elastic scattering of low-energy electrons by cyclohexane (c-C6H12). We employed the Schwinger multichannel method implemented with norm-conserving pseudopotentials in the static-exchange and static-exchange plus polarization approximations, for impact energies up to 30 eV. We compare our calculated integral cross section with experimental total cross sections available in the literature. We also compare our calculated differential cross sections (DCSs) with experimental results for benzene and experimental and theoretical results for 1,4-dioxane, in order to investigate the similarities between those molecules under electron collisions. Although benzene is a cyclic six-carbon molecule, as cyclohexane, we found that the differential cross sections of the latter are more similar to those of 1,4-dioxane than those of benzene. These similarities suggest that the geometry may play an important role in the behavior of the DCSs of these molecules. Our integral cross section displays a broad structure at around 8.5 eV, in agreement with the total cross section experimental data of 8 eV and vibrational excitation data of 7.5 eV. The present integral cross section also shows the presence of a Ramsauer-Townsend minimum at around 0.12 eV. In general, our integral cross section shows a qualitative agreement with the experimental total cross section.

  17. Maximum Likelihood Analysis of Low Energy CDMS II Germanium Data

    DOE PAGES

    Agnese, R.

    2015-03-30

    We report on the results of a search for a Weakly Interacting Massive Particle (WIMP) signal in low-energy data of the Cryogenic Dark Matter Search experiment using a maximum likelihood analysis. A background model is constructed using GEANT4 to simulate the surface-event background from Pb210decay-chain events, while using independent calibration data to model the gamma background. Fitting this background model to the data results in no statistically significant WIMP component. In addition, we also perform fits using an analytic ad hoc background model proposed by Collar and Fields, who claimed to find a large excess of signal-like events in ourmore » data. Finally, we confirm the strong preference for a signal hypothesis in their analysis under these assumptions, but excesses are observed in both single- and multiple-scatter events, which implies the signal is not caused by WIMPs, but rather reflects the inadequacy of their background model.« less

  18. Collisions of low-energy electrons with cyclohexane

    SciTech Connect

    Barbosa, Alessandra Souza; Bettega, Márcio H. F.

    2014-12-28

    We report calculated cross sections for elastic scattering of low-energy electrons by cyclohexane (c-C{sub 6}H{sub 12}). We employed the Schwinger multichannel method implemented with norm-conserving pseudopotentials in the static-exchange and static-exchange plus polarization approximations, for impact energies up to 30 eV. We compare our calculated integral cross section with experimental total cross sections available in the literature. We also compare our calculated differential cross sections (DCSs) with experimental results for benzene and experimental and theoretical results for 1,4-dioxane, in order to investigate the similarities between those molecules under electron collisions. Although benzene is a cyclic six-carbon molecule, as cyclohexane, we found that the differential cross sections of the latter are more similar to those of 1,4-dioxane than those of benzene. These similarities suggest that the geometry may play an important role in the behavior of the DCSs of these molecules. Our integral cross section displays a broad structure at around 8.5 eV, in agreement with the total cross section experimental data of 8 eV and vibrational excitation data of 7.5 eV. The present integral cross section also shows the presence of a Ramsauer-Townsend minimum at around 0.12 eV. In general, our integral cross section shows a qualitative agreement with the experimental total cross section.

  19. Structural surface investigations with low-energy backscattered electrons

    NASA Astrophysics Data System (ADS)

    De Crescenzi, Maurizio

    The development of electron spectroscopies based on inelastic scattering fine structure is driven mainly by the need for structural methods which allow the investigation of the geometrical environment of different atomic species of the surface region of the sample. The EELFS (Extended Energy Loss Fine Structure) technique, using low-kinetic-energy electrons (1000-2000 eV) in reflection geometry, has been proven a useful tool for local structural investigation of clean surfaces, thin films and chemisorbed species. The main appeal of this technique, besides its experimental accessibility, is that the data analysis follows the procedure used for EXAFS (Extended X-ray Absorption Fine Structure) spectroscopy to obtain the atomic selectivity, the radial distribution function, the coordination number and the thermal and anisotropic effects. The near-edge energy-loss feature has been used to investigate the density of empty states close to EF and it appeeal particularly sensitive for following the structural changes and for discriminating among various phases and compound formations which occur in the surface region. In this work I review some recent developments, applications and theoretical considerations of the EELFS technique to give local structural parameters and to assess the basic mechanisms which dominate the low-energy electron-surface interaction.

  20. Low-energy fusion caused by an interference

    NASA Astrophysics Data System (ADS)

    Ivlev, B.

    2013-03-01

    Fusion of two deuterons at room-temperature energy is studied. The nuclei are in vacuum with no connection to any external source (electric or magnetic field, illumination, surrounding matter, traps, etc.) which may accelerate them. The energy of the two nuclei is conserved and remains small during the motion through the Coulomb barrier. The penetration through this barrier, which is the main obstacle for low-energy fusion, strongly depends on a form of the incident flux on the Coulomb center at large distances from it. In contrast to the usual scattering, the incident wave is not a single plane wave but the certain superposition of plane waves of the same energy and various directions; for example, a convergent conical wave. As a result of interference, the wave function close to the Coulomb center is determined by a cusp caustic which is probed by de Broglie waves. The particle flux gets away from the cusp and moves to the Coulomb center providing a not negligible probability of fusion (cusp driven tunneling). Getting away from a caustic cusp also occurs in optics and acoustics.

  1. Investigation of low energy space plasma

    NASA Technical Reports Server (NTRS)

    Comfort, Richard H.; Horwitz, James L.

    1987-01-01

    An important modification was made in the method for computing ion densities from DE1/RIMS observations, based on the observed relationship between total plasma density and spacecraft potential. An iterative technique was developed to require that this relationship be preserved in all individual observations, not just in the average sense observed. Results of employing this technique were examined closely and are found to generally improve the final densities in terms of agreement with densities obtained from PWI upper hybrid frequency observations. It also has the effect of reducing scatter in the density vs. L profiles.

  2. Low energy beam transport system developments

    SciTech Connect

    Dudnikov, V.; Han, B.; Stockli, M.; Welton, R.; Dudnikova, G.

    2015-04-08

    For high brightness beam production it is important to preserve the brightness in the low energy beam transport system (LEBT) used to transport and match the ion beams to the next stage of acceleration, usually an RFQ. While electrostatic focusing can be problematic for high current beam transport, reliable electrostatic LEBT operation has been demonstrated with H{sup −} beams up to 60 mA. Now, however, it is commonly accepted that an optimal LEBT for high current accelerator applications consists of focusing solenoids with space charge compensation. Two-solenoid LEBTs are successfully used for high current (>100 mA) proton beam transport. Preservation of low emittances (~0.15 π mm-mrad) requires the addition of a heavy gas (Xe, Kr), which causes ~5% of proton loss in a 1 m long LEBT. Similar Xe densities would be required to preserve low emittances of H{sup −} beams, but such gas densities cause unacceptably high H{sup −} beam losses. A short LEBT with only one short solenoid, movable for RFQ matching, can be used for reduced negative ion stripping. A strong electrostatic-focusing LEBT has been successfully adopted for transport of high current H{sup −} beams in the SNS Front End. Some modifications of such electrostatic LEBTs are expected to improve the reliable transport of intense positive and negative ion beams without greatly degrading their low emittances. We concentrate on processes that determine the beam brightness degradation and on their prevention. Proposed improvements to the SNS electrostatic LEBT are discussed.

  3. Low-energy calculations for nuclear photodisintegration

    NASA Astrophysics Data System (ADS)

    Deflorian, S.; Efros, V. D.; Leidemann, W.

    2016-03-01

    In the Standard Solar Model a central role in the nucleosynthesis is played by reactions of the kind {}{Z_1}{A_1}{X_1} + {}{Z_2}{A_2}{X_2} to {}{Z_1 + {Z_2}}{A_1 + {A_2}}Y + γ , which enter the proton-proton chains. These reactions can also be studied through the inverse photodisintegration reaction. One option is to use the Lorentz Integral Transform approach, which transforms the continuum problem into a bound state-like one. A way to check the reliability of such methods is a direct calculation, for example using the Kohn Variational Principle to obtain the scattering wave function and then directly calculate the response function of the reaction.

  4. Low-energy positron interactions with krypton

    SciTech Connect

    Makochekanwa, C.; Machacek, J. R.; Jones, A. C. L.; Caradonna, P.; Slaughter, D. S.; McEachran, R. P.; Sullivan, J. P.; Buckman, S. J.; Bellm, S.; Lohmann, B.; Fursa, D. V.; Bray, I.; Mueller, D.W.; Stauffer, A. D.; Hoshino, M.

    2011-03-15

    Cross sections for positron scattering from krypton have been measured with an energy resolution of {approx}60 meV over the energy range 0.5-60 eV. Absolute values of the grand total ({sigma}{sub GT}), positronium formation ({sigma}{sub Ps}), and grand total minus positronium formation ({sigma}{sub GT}-{sigma}{sub Ps},) cross sections are presented. Theoretical estimations of {sigma}{sub GT} and {sigma}{sub GT}-{sigma}{sub Ps} are also performed for this target using the convergent close-coupling method and the relativistic optical potential approach. We also provide experimental and theoretical results for elastic differential cross sections, for selected energies both below and above the Ps threshold. Where available, the present results are compared to both experimental and theoretical values from the literature.

  5. Development of a Low-energy Trigger for VERITAS

    SciTech Connect

    Kildea, J.

    2008-12-24

    During the 2007/2008 observing season a low-energy trigger configuration was developed and tested for VERITAS. The configuration makes uses of the small ({approx}35 m) baseline between two of the VERITAS telescopes and employs a much lower discriminator threshold and tighter coincidence window compared to the standard VERITAS trigger. Five hours of Crab Nebula ON/OFF observations were obtained in low-energy mode and were used to test new low-energy analysis algorithms. We present some details of the VERITAS low-energy trigger and the associated data analysis.

  6. Interaction between Low Energy Ions and the Complicated Organism

    NASA Astrophysics Data System (ADS)

    Yu, Zeng-liang

    1999-12-01

    Low energy ions exist widely in natural world, but people pay a little attention on the interaction between low energy ions and matter, it is even more out of the question of studying on the relation of low energy ions and the complicated organism. The discovery of bioeffect induced by ion implantation has, however, opened a new branch in the field of ion beam application in life sciences. This paper reports recent advances in research on the role of low energy ions in chemical synthesis of the biomolecules and application in genetic modification.

  7. Low-Energy Ballistic Transfers to Lunar Halo Orbits

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.

    2009-01-01

    Recent lunar missions have begun to take advantage of the benefits of low-energy ballistic transfers between the Earth and the Moon rather than implementing conventional Hohmann-like lunar transfers. Both Artemis and GRAIL plan to implement low-energy lunar transfers in the next few years. This paper explores the characteristics and potential applications of many different families of low-energy ballistic lunar transfers. The transfers presented here begin from a wide variety of different orbits at the Earth and follow several different distinct pathways to the Moon. This paper characterizes these pathways to identify desirable low-energy lunar transfers for future lunar missions.

  8. A Germanium Detector with Optimized Compton Veto for High Sensitivity at Low Energy

    SciTech Connect

    Friedrich, S

    2011-11-30

    We have built a prototype germanium detector with a Compton veto that is optimized for high sensitivity in the low-energy range around {approx}100 keV. It is specifically designed to address the problem to directly detect plutonium gamma emissions in spent nuclear fuel by non-destructive assay. This is not possible with current detectors due to the large low-energy background of Compton-scattered high-energy radiation from the fission products, whose gamma flux is at least 6 to 7 orders of magnitude higher than the Pu signal. Our instrument is designed to assess the feasibility to selectively suppress the background in the low-energy region around {approx}100 keV with the strongest Pu X-ray and gamma emissions lines. It employs a thin Ge detector with a large Compton veto directly behind it to suppress the background from forward-scattered radiation by anti-coincidence vetoing. This report summarizes the design considerations and the performance of the instrument.

  9. Very low-energy neutrino interactions

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshio

    2015-05-01

    Neutrino-nucleus reaction cross sections are now evaluated rather accurately by shell-model (SM) or SM+RPA calculations based on recent advances in nuclear structure studies. Due to these achievements, reliable constraints on super-nova neutrino temperatures as well as neutrino oscillation parameters become possible. Supernova neutrino tempeatures are constrained from abundances of elements obtained by using new ν-nucleus reaction cross sections. A possibility of constructing supernova neutrino spectrum from beta-beam measurements is pointed out. Neutrino mass hierarchy and mixing angle θ13 can be determined from abundance ratio of 7Li/11B, which is sensitive to the MSW matter oscillation effects in supernova explosions. Inverted mass hierarchy is shown to be statistically more favored based on a recent analysis of presolar grains. Effects of neutrino-neutrino interactions are also shown to play important roles in r-process nucleosynthesis. Importance and possibilities of direct measurements of ν-induced cross sections on 40Ar and 208Pb are discussed for future supernova neutrino detections. Recent calculations of the cross sections for ν-40Ar are presented. The need for new theoretical evaluations of the cross sections for ν-208Pb is pointed out. Challenges to experiments on coherent elastic scattering are presented.

  10. Very low-energy neutrino interactions

    SciTech Connect

    Suzuki, Toshio

    2015-05-15

    Neutrino-nucleus reaction cross sections are now evaluated rather accurately by shell-model (SM) or SM+RPA calculations based on recent advances in nuclear structure studies. Due to these achievements, reliable constraints on super-nova neutrino temperatures as well as neutrino oscillation parameters become possible. Supernova neutrino tempeatures are constrained from abundances of elements obtained by using new ν-nucleus reaction cross sections. A possibility of constructing supernova neutrino spectrum from beta-beam measurements is pointed out. Neutrino mass hierarchy and mixing angle θ{sub 13} can be determined from abundance ratio of {sup 7}Li/{sup 11}B, which is sensitive to the MSW matter oscillation effects in supernova explosions. Inverted mass hierarchy is shown to be statistically more favored based on a recent analysis of presolar grains. Effects of neutrino-neutrino interactions are also shown to play important roles in r-process nucleosynthesis. Importance and possibilities of direct measurements of ν-induced cross sections on {sup 40}Ar and {sup 208}Pb are discussed for future supernova neutrino detections. Recent calculations of the cross sections for ν-{sup 40}Ar are presented. The need for new theoretical evaluations of the cross sections for ν-{sup 208}Pb is pointed out. Challenges to experiments on coherent elastic scattering are presented.

  11. Non-Gaussian beam dynamics in low energy antiproton storage rings

    NASA Astrophysics Data System (ADS)

    Resta-López, J.; Hunt, J. R.; Welsch, C. P.

    2016-10-01

    In low energy antiproton facilities, where electron cooling is fundamental, the cooling forces together with heating phenomena causing emittance blow-up, such as Intra Beam Scattering (IBS), result in highly non-Gaussian beam distributions. In these cases, a precise simulation of IBS effects is essential to realistically evaluate the long term beam evolution, taking into account the non-Gaussian characteristics of the beam. Here, we analyse the beam dynamics in the Extra Low ENergy Antiproton ring (ELENA), which is a new small synchrotron currently being constructed at CERN to decelerate antiprotons to energies as low as 100 keV. Simulations are performed using the code BETACOOL, comparing different models of IBS.

  12. Low-energy electron irradiation induced top-surface nanocrystallization of amorphous carbon film

    NASA Astrophysics Data System (ADS)

    Chen, Cheng; Fan, Xue; Diao, Dongfeng

    2016-10-01

    We report a low-energy electron irradiation method to nanocrystallize the top-surface of amorphous carbon film in electron cyclotron resonance plasma system. The nanostructure evolution of the carbon film as a function of electron irradiation density and time was examined by transmission electron microscope (TEM) and Raman spectroscopy. The results showed that the electron irradiation gave rise to the formation of sp2 nanocrystallites in the film top-surface within 4 nm thickness. The formation of sp2 nanocrystallite was ascribed to the inelastic electron scattering in the top-surface of carbon film. The frictional property of low-energy electron irradiated film was measured by a pin-on-disk tribometer. The sp2 nanocrystallized top-surface induced a lower friction coefficient than that of the original pure amorphous film. This method enables a convenient nanocrystallization of amorphous surface.

  13. What is a low-energy house and who cares?

    SciTech Connect

    Litt, B.R.

    1994-12-01

    Most energy analysts view low-energy houses as good things, yet differ in their expectations of what exactly a low energy house is. There are two intertwining threads to this report. The first is an evaluation of 50 buildings that have been claimed to be low-energy residences, for which monitored energy performance data have been collected. These data represent the preliminary effort in the ongoing update of the Buildings Energy-Use Compilation and Analysis (BECA) data base for new residences. The second thread concerns the definition of a low-energy house. After the elements of a definition are presented, their implications for actors involved in providing housing are identified. Several more tractable definitions are applied to the houses in this compilation. The outcomes illustrate ways in which different interests are served by various definitions. Different definitions can yield very different energy rankings. No single definition of a low-energy house is universally applicable.

  14. Precision measurement of quenching factors for low-energy nuclear recoils at TUNL

    NASA Astrophysics Data System (ADS)

    Rich, Grayson; Barbeau, Phil; Howell, Calvin; Karwowski, Hugon

    2014-03-01

    With detector technologies becoming increasingly sensitive to exotic events, a thorough understanding of signal yield as a function of deposited energy is required for appropriate interpretation of results from cutting edge detector systems. Elastic neutron scattering is a probe which has been used to mimic the nuclear recoils which may be produced in detection media by light-WIMP interactions or coherent neutrino-nucleus scattering (CNS). We have built at the Triangle Universities Nuclear Laboratory (TUNL) a facility which produces pulsed, collimated, low-energy, quasi-monoenergetic neutron beams using the 7Li(p,n) reaction, resulting in fluxes of ~ 1 neutrons / (s . cm2) at ~90 cm from the neutron-production target. The first precision results from this facility are reported for ultra-low-energy recoils in NaI(Tl) and CsI(Na) and future plans are outlined, including measurements on candidate materials for a CNS detector that can potentially be fielded at the Spallation Neutron Source of Oak Ridge National Laboratory as a part the Coherent Scatter Initiative (CSI). We discuss the implications of new, precise measurements of quenching factors on neutrino detectors and on current- and next-generation light-WIMP searches, particularly the DAMA experiment.

  15. Magnetic Density of States at Low Energy in Geometrically Frustrated Systems

    NASA Astrophysics Data System (ADS)

    Yaouanc, A.; de Réotier, P. Dalmas; Glazkov, V.; Marin, C.; Bonville, P.; Hodges, J. A.; Gubbens, P. C.; Sakarya, S.; Baines, C.

    2005-07-01

    Using muon-spin-relaxation measurements we show that the pyrochlore compound Gd2Ti2O7, in its magnetically ordered phase below ˜1 K, displays persistent spin dynamics down to temperatures as low as 20 mK. The characteristics of the induced muon relaxation can be accounted for by a scattering process involving two magnetic excitations, with a density of states characterized by an upturn at low energy and a small gap depending linearly on the temperature. We propose that such a density of states is a generic feature of geometrically frustrated magnetic materials.

  16. Long-Range Order and Low-Energy Spectrum of Diluted 2D Quantum Antiferromagnet

    SciTech Connect

    Chernyshev, A. L.; Chen, Y. C.; Castro Neto, A. H.

    2001-08-06

    The problem of a diluted two-dimensional quantum antiferromagnet on a square lattice is studied using spin-wave theory. The influence of impurities on static and dynamic properties is investigated and a good agreement with experiments and Monte Carlo data is found. The hydrodynamic description of spin waves breaks down at characteristic wavelengths {Lambda}{approx}>exp(const/x) , x being an impurity concentration, while the order parameter is free from anomalies. We argue that this dichotomy originates from strong scattering of the low-energy excitations in two dimensions.

  17. Integration of the low-energy particle track simulation code in Geant4

    NASA Astrophysics Data System (ADS)

    Arce, Pedro; Muñoz, Antonio; Moraleda, Montserrat; Gomez Ros, José María; Blanco, Fernando; Perez, José Manuel; García, Gustavo

    2015-08-01

    The Low-Energy Particle Track Simulation code (LEPTS) is a Monte Carlo code developed to simulate the damage caused by radiation at molecular level. The code is based on experimental data of scattering cross sections, both differential and integral, and energy loss data, complemented with theoretical calculations. It covers the interactions of electrons and positrons from energies of 10 keV down to 0.1 eV in different biologically relevant materials. In this article we briefly mention the main characteristics of this code and we present its integration within the Geant4 Monte Carlo toolkit.

  18. Past, present and future low energy antiproton facilities at CERN

    NASA Astrophysics Data System (ADS)

    Bartmann, W.; Belochitskii, P.; Breuker, H.; Butin, F.; Carli, C.; Eriksson, T.; Maury, S.; Oelert, W.; Pasinelli, S.; Tranquille, G.

    2014-05-01

    Low energy antiprotons are available for physics experiments at CERN since the 1980s and have been used by a large variety of experiments. The Low Energy Antiproton Ring LEAR has been constructed as a complementary use of antiprotons available at that time for high energy physics and delivered beam to experiments mainly using slow extraction. After completion of LEAR exploitation, the Antiproton Decelerator (AD) was constructed (adaptation of the existing Antiproton Collector, AC) to allow for a simpler low energy antiproton scheme (only one accelerator operated with Antiprotons) with fast extraction well suited for trap experiments. The Extra Low ENergy Antiproton ring ELENA is a small synchrotron presently constructed to further decelerate antiprotons from the AD in a controlled manner, and to reduce emittances with the help of an electron cooler to improve the capture efficiencies of existing experiments and allow for additional ones.

  19. Radial Flux Distribution of Low-Energy Neutrons.

    ERIC Educational Resources Information Center

    Higinbotham, J.

    1979-01-01

    Describes an experiment designed to illustrate the basic principle involved in the process of moderation of fast neutrons by water, and the monitoring of the low-energy neutron flux using indium as a probe. (GA)

  20. Biological assessments for the low energy demonstration accelerator, 1996

    SciTech Connect

    Cross, S.

    1997-03-01

    This report discusses the biological impact to the area around the Los Alamos National Laboratory of the Low Energy Demonstration Accelerator. In particular the impact to the soils, water quality, vegetation, and wildlife are discussed.

  1. Surface Passivation and Junction Formation Using Low Energy Hydrogen Implants

    NASA Technical Reports Server (NTRS)

    Fonash, S. J.

    1985-01-01

    New applications for high current, low energy hydrogen ion implants on single crystal and polycrystal silicon grain boundaries are discussed. The effects of low energy hydrogen ion beams on crystalline Si surfaces are considered. The effect of these beams on bulk defects in crystalline Si is addressed. Specific applications of H+ implants to crystalline Si processing are discussed. In all of the situations reported on, the hydrogen beams were produced using a high current Kaufman ion source.

  2. Strong flux of low-energy neutrons produced by thunderstorms.

    PubMed

    Gurevich, A V; Antonova, V P; Chubenko, A P; Karashtin, A N; Mitko, G G; Ptitsyn, M O; Ryabov, V A; Shepetov, A L; Shlyugaev, Yu V; Vildanova, L I; Zybin, K P

    2012-03-23

    We report here for the first time about the registration of an extraordinary high flux of low-energy neutrons generated during thunderstorms. The measured neutron count rate enhancements are directly connected with thunderstorm discharges. The low-energy neutron flux value obtained in our work is a challenge for the photonuclear channel of neutron generation in thunderstorm: the estimated value of the needed high-energy γ-ray flux is about 3 orders of magnitude higher than that one observed.

  3. Understanding Low Energy Gamma Emission from Fission and Capture with DANCE

    NASA Astrophysics Data System (ADS)

    Wilburn, Grey; Couture, Aaron; Mosby, Shea

    2012-10-01

    Los Alamos National Laboratory's Detector for Advanced Neutron Capture Experiments (DANCE) consists of 160 barium fluoride (BaF2) detectors in a 4π array used to study cross-section measurements from neutron capture reactions. Further, recent studies have taken advantage of DANCE to study the gamma emission from fission, which is not well characterized. Neutron capture is studied because of its relevance to nuclear astrophysics (almost all elements heavier than iron are formed via neutron capture) and nuclear energy, where neutron capture is a poison in the reactor. Gamma ray cascades following neutron capture and fission include photons with energies between 100 keV and 10 MeV. DANCE uses a ^6LiH sphere to attenuate scattered neutrons, the primary background in DANCE. Unfortunately, it also attenuates low energy gamma rays. In order to quantify this effect and validate simulations, direct measurements of low energy gammas were made with a high purity germanium (HPGe) crystal. HPGe's allow for high resolution measurements of low energy gamma rays that are not possible using the BaF2 crystals. The results and their agreement with simulations will be discussed.

  4. Potential for luminosity improvement for low-energy RHIC operation with long bunches

    SciTech Connect

    Fedotov, A.; Blaskiewicz, M.

    2012-02-10

    Electron cooling was proposed to increase luminosity of the RHIC collider for heavy ion beams at low energies. Luminosity decreases as the square of bunch intensity due to the beam loss from the RF bucket as a result of the longitudinal intra beam scattering (IBS), as well as due to the transverse emittance growth because of the transverse IBS. Both transverse and longitudinal IBS can be counteracted with electron cooling. This would allow one to keep the initial peak luminosity close to constant throughout the store essentially without the beam loss. In addition, the phase-space density of the hadron beams can be further increased by providing stronger electron cooling. Unfortunately, the defining limitation for low energies in RHIC is expected to be the space charge. Here we explore an idea of additional improvement in luminosity, on top of the one coming from just IBS compensation and longer stores, which may be expected if one can operate with longer bunches at the space-charge limit in a collider. This approach together with electron cooling may result in about 10-fold improvement in total luminosity for low-energy RHIC program.

  5. Recent results from the TwinSol low-energy RIB facility

    NASA Astrophysics Data System (ADS)

    Becchetti, F. D.; Kolata, J. J.

    2016-06-01

    We report on some of the recent developments and experimental work done at the twin-solenoid low-energy radioactive-ion-beam (RIB) facility TwinSol installed at the U Notre Dame 10 MV FN tandem accelerator. The TwinSol facility is a joint project of the University of Michigan (UM) and the University of Notre Dame (UND), and includes several U.S. and foreign collaborators. A number of significant experiments including RIB-induced transfer reactions, elastic scattering, resonant scattering, and fusion at energies near and well below the Coulomb barrier have been performed with this facility. Several of these as well as future work and upgrades planned will be described.

  6. Low-energy parameters of neutron-neutron interaction in the effective-range approximation

    SciTech Connect

    Babenko, V. A.; Petrov, N. M.

    2013-06-15

    The effect of the mass difference between the charged and neutral pions on the low-energy parameters of nucleon-nucleon interaction in the {sup 1}S{sub 0} state is studied in the effective-range approximation. On the basis of experimental values of the singlet parameters of neutron-proton scattering and the experimental value of the virtual-state energy for the neutron-neutron systemin the {sup 1}S{sub 0} state, the following values were obtained for the neutron-neutron scattering length and effective range: a{sub nn} = -16.59(117) fm and r{sub nn} = 2.83(11) fm. The calculated values agree well with present-day experimental results.

  7. Photon Strength and the Low-Energy Enhancement

    SciTech Connect

    Wiedeking, M; Bernstein, L A; Krticka, M; Bleuel, D L; Allmond, J M; Basunia, M S; Burke, J T; Fallon, P; Firestone, R B; Goldblum, B L; Hatarik, R; Lake, P T; Lee, I Y; Lesher, S R; Paschalis, S; Petri, M; Phair, L; Scielzo, N D

    2012-02-22

    The ability of atomic nuclei to emit and absorb photons with energy E{sub {gamma}} is known as the photon strength function f(E{sub {gamma}}). It has direct relevance to astrophysical element formation via neutron capture processes due to its central role in nuclear reactions. Studies of f(E{sub {gamma}}) have benefited from a wealth of data collected in neutron capture and direct reactions but also from newly commissioned inelastic photon scattering facilities. The majority of these experimental methods, however, rely on the use of models because measured {gamma}-ray spectra are simultaneously sensitive to both the nuclear level density and f(E{sub {gamma}}). As excitation energy increases towards the particle separation energies, the level density increases rapidly, creating the quasi-continuum. Nuclear properties in this excitation energy region are best characterized using statistical quantities, such as f(E{sub {gamma}}). A point of contention in studies of the quasi-continuum has been an unexpected and unexplained increase in f(E{sub {gamma}}) at low {gamma}-ray energies (i.e. below E{sub {gamma}} {approx}3 MeV) in a subset of light-to-medium mass nuclei. Ideally, a new model-independent experimental technique is required to address questions regarding the existence and origin of this low-energy enhancement in f(E{sub {gamma}}). Here such a model-independent approach is presented for determining the shape of f(E{sub {gamma}}) over a wide range of energies. The method involves the use of coupled high-resolution particle and {gamma}-ray spectroscopy to determine the emission of {gamma} rays from the quasi-continuum in a nucleus with defined excitation energy to individual discrete levels of known spins and parities. This method shares characteristics of two neutron capture-based techniques: the Average Resonance Capture (ARC) and the Two-Step Cascade analysis (TSC). The power of the new technique lies in the additional ability to positively identify primary

  8. A G/NARRLI Effort. Measuring the Ionization Yield of Low-Energy Nuclear Recoils in Liquid Argon

    SciTech Connect

    Joshi, Tenzing Henry Yatish

    2014-01-01

    Liquid argon has long been used for particle detection due to its attractive drift properties, ample abundance, and reasonable density. The response of liquid argon to lowenergy O(102 -1044 eV) interactions is, however, largely unexplored. Weakly interacting massive particles such as neutrinos and hypothetical dark-matter particles (WIMPs) are predicted to coherently scatter on atomic nuclei, leaving only an isolated low-energy nuclear recoil as evidence. The response of liquid argon to low-energy nuclear recoils must be studied to determine the sensitivity of liquid argon based detectors to these unobserved interactions. Detectors sensitive to coherent neutrino-nucleus scattering may be used to monitor nuclear reactors from a distance, to detect neutrinos from supernova, and to test the predicted behavior of neutrinos. Additionally, direct detection of hypothetical weakly interacting dark matter would be a large step toward understanding the substance that accounts for nearly 27% of the universe. In this dissertation I discuss a small dual-phase (liquid-gas) argon proportional scintillation counter built to study the low-energy regime and several novel calibration and characterization techniques developed to study the response of liquid argon to low-energy O(102 -104 eV) interactions.

  9. New insights gained on mechanisms of low-energy proton-induced SEUs by minimizing energy straggle

    SciTech Connect

    Dodds, Nathaniel Anson; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Martinez, Marino J.; Black, Jeffrey D.; Marshall, P. W.; Reed, R. A.; McCurdy, M. W.; Weller, R. A.; Pellish, J. A.; Rodbell, K. P.; Gordon, M. S.

    2015-12-01

    In this study, we present low-energy proton single-event upset (SEU) data on a 65 nm SOI SRAM whose substrate has been completely removed. Since the protons only had to penetrate a very thin buried oxide layer, these measurements were affected by far less energy loss, energy straggle, flux attrition, and angular scattering than previous datasets. The minimization of these common sources of experimental interference allows more direct interpretation of the data and deeper insight into SEU mechanisms. The results show a strong angular dependence, demonstrate that energy straggle, flux attrition, and angular scattering affect the measured SEU cross sections, and prove that proton direct ionization is the dominant mechanism for low-energy proton-induced SEUs in these circuits.

  10. New insights gained on mechanisms of low-energy proton-induced SEUs by minimizing energy straggle

    DOE PAGES

    Dodds, Nathaniel Anson; Dodd, Paul E.; Shaneyfelt, Marty R.; Sexton, Frederick W.; Martinez, Marino J.; Black, Jeffrey D.; Marshall, P. W.; Reed, R. A.; McCurdy, M. W.; Weller, R. A.; et al

    2015-12-01

    In this study, we present low-energy proton single-event upset (SEU) data on a 65 nm SOI SRAM whose substrate has been completely removed. Since the protons only had to penetrate a very thin buried oxide layer, these measurements were affected by far less energy loss, energy straggle, flux attrition, and angular scattering than previous datasets. The minimization of these common sources of experimental interference allows more direct interpretation of the data and deeper insight into SEU mechanisms. The results show a strong angular dependence, demonstrate that energy straggle, flux attrition, and angular scattering affect the measured SEU cross sections, andmore » prove that proton direct ionization is the dominant mechanism for low-energy proton-induced SEUs in these circuits.« less

  11. Inelastic cross sections for low-energy electrons in liquid water: exchange and correlation effects.

    PubMed

    Emfietzoglou, Dimitris; Kyriakou, Ioanna; Garcia-Molina, Rafael; Abril, Isabel; Nikjoo, Hooshang

    2013-11-01

    Low-energy electrons play a prominent role in radiation therapy and biology as they are the largest contributor to the absorbed dose. However, no tractable theory exists to describe the interaction of low-energy electrons with condensed media. This article presents a new approach to include exchange and correlation (XC) effects in inelastic electron scattering at low energies (below ∼10 keV) in the context of the dielectric theory. Specifically, an optical-data model of the dielectric response function of liquid water is developed that goes beyond the random phase approximation (RPA) by accounting for XC effects using the concept of the many-body local-field correction (LFC). It is shown that the experimental energy-loss-function of liquid water can be reproduced by including into the RPA dispersion relations XC effects (up to second order) calculated in the time-dependent local-density approximation with the addition of phonon-induced broadening in N. D. Mermin's relaxation-time approximation. Additional XC effects related to the incident and/or struck electrons are included by means of the vertex correction calculated by a modified Hubbard formula for the exchange-only LFC. Within the first Born approximation, the present XC corrections cause a significantly larger reduction (∼10-50%) to the inelastic cross section compared to the commonly used Mott and Ochkur approximations, while also yielding much better agreement with the recent experimental data for amorphous ice. The current work offers a manageable, yet rigorous, approach for including non-Born effects in the calculation of inelastic cross sections for low-energy electrons in liquid water, which due to its generality, can be easily extended to other condensed media.

  12. Certification of NIST Room Temperature Low-Energy and High-Energy Charpy Verification Specimens

    PubMed Central

    Lucon, Enrico; McCowan, Chris N.; Santoyo, Ray L.

    2015-01-01

    The possibility for NIST to certify Charpy reference specimens for testing at room temperature (21 °C ± 1 °C) instead of −40 °C was investigated by performing 130 room-temperature tests from five low-energy and four high-energy lots of steel on the three master Charpy machines located in Boulder, CO. The statistical analyses performed show that in most cases the variability of results (i.e., the experimental scatter) is reduced when testing at room temperature. For eight out of the nine lots considered, the observed variability was lower at 21 °C than at −40 °C. The results of this study will allow NIST to satisfy requests for room-temperature Charpy verification specimens that have been received from customers for several years: testing at 21 °C removes from the verification process the operator’s skill in transferring the specimen in a timely fashion from the cooling bath to the impact position, and puts the focus back on the machine performance. For NIST, it also reduces the time and cost for certifying new verification lots. For one of the low-energy lots tested with a C-shaped hammer, we experienced two specimens jamming, which yielded unusually high values of absorbed energy. For both specimens, the signs of jamming were clearly visible. For all the low-energy lots investigated, jamming is slightly more likely to occur at 21 °C than at −40 °C, since at room temperature low-energy samples tend to remain in the test area after impact rather than exiting in the opposite direction of the pendulum swing. In the evaluation of a verification set, any jammed specimen should be removed from the analyses. PMID:26958453

  13. Design of low energy bunch compressors with space charge effects

    NASA Astrophysics Data System (ADS)

    He, A.; Willeke, F.; Yu, L. H.; Yang, L.; Shaftan, T.; Wang, G.; Li, Y.; Hidaka, Y.; Qiang, J.

    2015-01-01

    In this paper, we explore a method to manipulate low energy electron bunches in a space charge dominated regime, and we use this method to design low energy linac bunch compressors to compress electron bunches in a space charge dominated regime. In the method, we use the space charge effects instead of avoiding them; i.e., we use the space charge forces to generate the required energy chirp instead of the ordinary method which uses the rf accelerating system to generate the chirp. We redefine the concepts of the dispersion function and beta functions in a space charge dominated regime to guide the optimization. Using this method, we study the low energy (5-22 MeV) linac bunch compressor design to produce short (˜150 fs ) and small size (˜30 μ m ) bunches for the electron beam slicing project. The low energy linac bunch compressors work in a space charge dominated regime, and the bunches at the downstream of the gun have a negative energy chirp due to the space charge effects. To provide compression for the negative energy chirped bunch, we design a positive R56 dispersive section using a four-dipole chicane with several quadrupole magnets. We have designed low energy linac bunch compressors with different photocathode rf guns. For example, one linac bunch compressor with the BNL photocathode electron rf gun has achieved a low energy bunch with the 166 fs rms bunch length, 28 and 31 μ m rms beam size in the vertical and horizontal directions, respectively, at 5 MeV with 50 pC charge. Another example with LBNL's very-high frequency gun has achieved a low energy bunch with the 128 fs rms bunch length, 42 and 25 μ m rms beam size in the vertical and horizontal directions, respectively, at 22 MeV with 200 pC charge.

  14. Prediction of background in low-energy spectrum of Phoswich detector.

    PubMed

    Arun, B; Manohari, M; Mathiyarasu, R; Rajagopal, V; Jose, M T

    2014-12-01

    In vivo monitoring of actinides in occupational workers is done using Phoswich detector by measuring the low-energy X ray and gamma rays. Quantification of actinides like plutonium and americium in the lungs is extremely difficult due to higher background in the low-energy regions, which is from ambient background as well as from the subject. In the latter case, it is mainly due to the Compton scattering of body potassium, which varies person-to-person. Hence, an accurate prediction of subject-specific background counts in the lower-energy regions is an essential element in the in vivo measurement of plutonium and americium. Empirical equations are established for the prediction of background count rate in (239)Pu and (241)Am lower-energy regions, called 'target regions', as a function of count rate in the monitoring region (97-130 keV)/(40)K region in the high-energy spectrum, weight-to-height ratio of the subject (scattering parameter) and the gender.

  15. A Compton-Vetoed Germanium Detector with Increased Sensitivity at Low Energies

    SciTech Connect

    Friedrich, S; Bates, C; Drury, O B; Burks, M; DiPrete, D

    2012-03-29

    The difficulty to directly detect plutonium in spent nuclear fuel due to the high Compton background of the fission products motivates the design of a Gamma detector with improved sensitivity at low energies. We have built such a detector by operating a thin high-purity Ge detector with a large scintillator Compton veto directly behind it. The Ge detector is thin to absorb just the low-energy Pu radiation of interest while minimizing Compton scattering of high energy radiation from the fission products. The subsequent scintillator is large so that forward scattered photons from the Ge detector interact in it at least once to provide an anti-coincidence veto for the Ge detector. For highest sensitivity, additional material in the line-of-sight is minimized, the radioactive sample is kept thin, and its radiation is collimated. We will discuss the instrument design, and demonstrate the feasibility of the approach with a prototype that employs two large CsI scintillator vetoes. Initial spectra of a thin Cs-137 calibration source show a background suppression of a factor of {approx}2.5 at {approx}100 keV, limited by an unexpectedly thick 4 mm dead layer in the Ge detector.

  16. Characterization of hydrogen binding to tungsten and beryllium surfaces using low energy ion beam analysis

    NASA Astrophysics Data System (ADS)

    Kolasinski, Robert; Whaley, Josh

    2015-11-01

    In this study, we use low energy ion beam analysis to determine how hydrogen interacts with tungsten and beryllium surfaces. The goal of this work is to provide insight into processes that contribute to recycling from plasma-facing surfaces in magnetic fusion devices. Here we have applied low energy ion scattering (LEIS) to enable detection of adsorbed hydrogen at sub-monolayer resolution and to provide isotopic sensitivity. We probe the surfaces of interest with He + and Ne + at energies less than 5 keV to determine the structure and composition of the first few atomic layers. This approach enables us to examine how hydrogen surface concentrations evolve in real time, providing insight into adsorption kinetics. In addition, we have developed a means of determining the hydrogen binding configuration at different temperatures by exploiting mechanisms of ion channeling along surfaces. Using these methods, we have been able to identify hydrogen binding configurations for the W(100) +H, W(110) +H, and Be(0001) +H adsorption systems. We also report on our efforts to more accurately and efficiently model atomic collisions during scattering, key steps needed to extract structural information from LEIS signals. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  17. Halo Nuclei in a three-body model and universal characteristics of low-energy few-body systems

    SciTech Connect

    Tomio, Lauro; Yamashita, M. T.; Frederico, T.; Delfino, A.

    2010-08-04

    Within general characteristics of low-energy few-body systems, we revise some well-known correlations found in nuclear physics, and the properties of low-mass halo nuclei in a three-body neutron-neutron-core model. In this context, near the critical conditions for the occurrence of an Efimov state, we report some results obtained for the neutron-{sup 19}C elastic scattering.

  18. Low energy availability in the marathon and other endurance sports.

    PubMed

    Loucks, Anne B

    2007-01-01

    Energy availability is the amount of dietary energy remaining after exercise training for all other metabolic processes. Excessively low energy availability impairs reproductive and skeletal health, although genetics and age may alter an individual's initial conditions and sensitivity when low energy availability is imposed. Many marathon runners and other endurance athletes reduce energy availability either (i) intentionally to modify body size and composition for improving performance; (ii) compulsively in a psychopathological pattern of disordered eating; or (iii) inadvertently because there is no strong biological drive to match energy intake to activity-induced energy expenditure. Inadvertent low energy availability is more extreme when consuming a low fat, high carbohydrate diet. Low energy availability, reproductive disorders, low bone mineral density and stress fractures are more common in female than male athletes. Functional menstrual disorders caused by low energy availability should be diagnosed by excluding diseases that also disrupt menstrual cycles. To determine energy availability (in units of kilocalories or kilojoules per kilogram of fat-free mass), athletes can record their diets and use diet analysis software to calculate energy intake, measure energy expenditure during exercise using a heart monitor and measure fat-free mass using a bioelectrical impedance body composition scale. All are commercially available at consumer prices.

  19. A New HOM Water Cooled Absorber for the PEP-II B-factory Low Energy Ring

    SciTech Connect

    Weathersby, Stephen; Kosovsky, Michael; Kurita, Nadine; Novokhatski, Alexander; Seeman, John; /SLAC

    2006-09-05

    At high currents and small bunch lengths beam line components in the PEP-II B-factory experience RF induced heating from higher order RF modes (HOMs) produced by scattered intense beam fields. A design for a passive HOM water cooled absorber for the PEP-II low energy ring is presented. This device is situated near HOM producing beamline components such as collimators and provide HOM damping for dipole and quadrupole modes without impacting beam impedance. We optimized the impedance characteristics of the device through the evaluation of absorber effectiveness for specific modes using scattering parameter and wakefield analysis. Operational results are presented and agree very well with the predicted effectiveness.

  20. Hadronic Interactions from Lattice QCD

    SciTech Connect

    Konstantinos Orginos

    2006-03-19

    In this talk I discuss a few recent results on lattice calculations of scattering lengths in hadronic processes. In particular, I present the scattering length of the pion-pion scattering in the I=2 channel and the nucleon-nucleon {sup 1}S{sub 0} channel and {sup 3}S{sub 1}-{sup 3}D{sub 1} coupled channels.

  1. EVOLUTION OF THE CRAB NEBULA IN A LOW ENERGY SUPERNOVA

    SciTech Connect

    Yang, Haifeng; Chevalier, Roger A. E-mail: rac5x@virginia.edu

    2015-06-20

    The nature of the supernova leading to the Crab Nebula has long been controversial because of the low energy that is present in the observed nebula. One possibility is that there is significant energy in extended fast material around the Crab but searches for such material have not led to detections. An electron capture supernova model can plausibly account for the low energy and the observed abundances in the Crab. Here, we examine the evolution of the Crab pulsar wind nebula inside a freely expanding supernova and find that the observed properties are most consistent with a low energy event. Both the velocity and radius of the shell material, and the amount of gas swept up by the pulsar wind point to a low explosion energy (∼10{sup 50} erg). We do not favor a model in which circumstellar interaction powers the supernova luminosity near maximum light because the required mass would limit the freely expanding ejecta.

  2. 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.

  3. Feasibility of Electron Cooling for Low-Energy RHIC Operation

    SciTech Connect

    Fedotov,A.; Ben-Zvi, I.; Chang, X.; Kayran, D.; Litvinenko, V.; Pozdeyev, E.; Satogata, T.

    2008-04-01

    A concrete interest in running RHIC at low energies in a range of 2.5-25 GeV/nucleon total energy of a single beam has recently emerged. Providing collisions in this energy range, which in the RHIC case is termed 'low-energy' operation, will help to answer one of the key questions in the field of QCD about existence and location of a critical point on the QCD phase diagram. However, luminosity projections are relatively low for the lowest energy points of interest. Luminosity improvement can be provided with electron cooling applied directly in RHIC at low energies. This report summarizes the expected luminosity improvement with electron cooling, possible technical approaches and various limitations.

  4. The problem of low energy particle measurements in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Whipple, E. C., Jr.

    1978-01-01

    The accurate measurement of low energy (less than 100 eV) particle properties in the magnetosphere has been difficult, partly because of the low density of such particles, but more particularly because of spacecraft interference effects. Some early examples of how these phenomena have affected particle measurements on an OGO spacecraft are presented. Data obtained with the UCSD particle detectors on ATS-6 are then presented showing how some of these difficulties have been partially overcome. Future measurements of low energy particles in the magnetosphere can be improved by: (1) improving the low energy resolution of detectors; (2) building electrostatically clean spacecraft; (3) controlling spacecraft potential; and (4) using auxiliary measurements, particularly wave data.

  5. Evolution of the Crab Nebula in a Low Energy Supernova

    NASA Astrophysics Data System (ADS)

    Yang, Haifeng; Chevalier, Roger A.

    2015-06-01

    The nature of the supernova leading to the Crab Nebula has long been controversial because of the low energy that is present in the observed nebula. One possibility is that there is significant energy in extended fast material around the Crab but searches for such material have not led to detections. An electron capture supernova model can plausibly account for the low energy and the observed abundances in the Crab. Here, we examine the evolution of the Crab pulsar wind nebula inside a freely expanding supernova and find that the observed properties are most consistent with a low energy event. Both the velocity and radius of the shell material, and the amount of gas swept up by the pulsar wind point to a low explosion energy (∼1050 erg). We do not favor a model in which circumstellar interaction powers the supernova luminosity near maximum light because the required mass would limit the freely expanding ejecta.

  6. IONS (ANURADHA): Ionization states of low energy cosmic rays

    NASA Technical Reports Server (NTRS)

    Biswas, S.; Chakraborti, R.; Cowsik, R.; Durgaprasad, N.; Kajarekar, P. J.; Singh, R. K.; Vahia, M. N.; Yadav, J. S.; Dutt, N.; Goswami, J. N.

    1987-01-01

    IONS (ANURADHA), the experimental payload designed specifically to determine the ionization states, flux, composition, energy spectra and arrival directions of low energy (10 to 100 MeV/amu) anomalous cosmic ray ions of helium to iron in near-Earth space, had a highly successful flight and operation Spacelab-3 mission. The experiment combines the accuracy of a highly sensitive CR-39 nuclear track detector with active components included in the payload to achieve the experimental objectives. Post-flight analysis of detector calibration pieces placed within the payload indicated no measurable changes in detector response due to its exposure in spacelab environment. Nuclear tracks produced by alpha-particles, oxygen group and Fe ions in low energy anomalous cosmic rays were identified. It is calculated that the main detector has recorded high quality events of about 10,000 alpha-particles and similar number of oxygen group and heavier ions of low energy cosmic rays.

  7. Light element production by low energy nuclei from massive stars

    NASA Technical Reports Server (NTRS)

    Vangioni-Flam, E.; Casse, M.; Ramaty, R.

    1997-01-01

    The Orion complex is a source of gamma rays attributed to the de-excitation of fast carbon and oxygen nuclei excited through interactions with ambient hydrogen and helium. This has consequences for the production and evolution of light isotopes in the Galaxy, as massive stars appear as prolific sources of C-O rich low energy nuclei. The different stages of massive star evolution are considered in relation to the acceleration of nuclei to moderate energies. It is concluded that the low energy nuclear component originating from massive stars plays a larger role than the usual Galactic cosmic rays in shaping the evolution of Li-6, Be-9, B-10 and B-11, especially in the early Galactic evolution. The enhancement of the B-11/B-10 ratio observed in meteorites and in the interstellar medium is attributed to the interaction of low energy carbon nuclei with ambient H and to a lesser degree, to neutrino spallation.

  8. Low-energy physics of high-temperature superconductors

    SciTech Connect

    Emery, V.J. . Physics Dept.); Kivelson, S.A. . Dept. of Physics)

    1992-01-01

    It is argued that the low-energy properties of high temperature superconductors are dominated by the interaction between the mobile holes and a particular class of collective modes, corresponding to local large-amplitude low-energy fluctuations in the hole density. The latter are a consequence of the competition between the effects of long-range Coulomb interactions and the tendency of a low concentration of holes in an antiferromagnet to phase separate. The low-energy behavior of the system is governed by the same fixed point as the two-channel Kondo problem, which accounts for the universality'' of the properties of the cuprate superconductors. Predictions of the optical properties and the spin dynamics are compared with experiment. The pairing resonance of the two Kondo problem gives a mechanism of high temperature superconductivity with an unconventional symmetry of the order parameter.

  9. Low-energy physics of high-temperature superconductors

    SciTech Connect

    Emery, V.J.; Kivelson, S.A.

    1992-09-01

    It is argued that the low-energy properties of high temperature superconductors are dominated by the interaction between the mobile holes and a particular class of collective modes, corresponding to local large-amplitude low-energy fluctuations in the hole density. The latter are a consequence of the competition between the effects of long-range Coulomb interactions and the tendency of a low concentration of holes in an antiferromagnet to phase separate. The low-energy behavior of the system is governed by the same fixed point as the two-channel Kondo problem, which accounts for the ``universality`` of the properties of the cuprate superconductors. Predictions of the optical properties and the spin dynamics are compared with experiment. The pairing resonance of the two Kondo problem gives a mechanism of high temperature superconductivity with an unconventional symmetry of the order parameter.

  10. Techniques and methods for the low-energy neutrino detection

    NASA Astrophysics Data System (ADS)

    Ranucci, Gioacchino

    2016-04-01

    Low-energy neutrino physics and astrophysics has been one of the most active field of particle physics research over the past two decades, achieving important and sometimes unexpected results, which have paved the way for a bright future of further exciting studies. The methods, the techniques and the technologies employed for the construction of the many experiments which acted as important players in this area of investigation have been crucial elements to reach the many accumulated physics successes. The topic covered in this review is, thus, the description of the main features of the set of methodologies at the basis of the design, construction and operation of low-energy neutrino detectors.

  11. Cluster structure of a low-energy resonance in tetraneutron

    SciTech Connect

    Lashko, Yu. A. Filippov, G. F.

    2008-02-15

    We theoretically investigate the possibility for a tetraneutron to exist as a low-energy resonance state. We explore a microscopic model based on the assumption that the tetraneutron can be treated as a compound system, where {sup 3}n + n and {sup 2}n + {sup 2}n coupled cluster configurations coexist. The influence of the Pauli principle on the kinetic energy of the relative motion of the neutron clusters is shown to result in their attraction. The strength of such attraction is high enough to ensure the existence of a low-energy resonance in the tetraneutron, provided that the oscillator length is large enough.

  12. Strong flux of low-energy neutrons produced by thunderstorms.

    PubMed

    Gurevich, A V; Antonova, V P; Chubenko, A P; Karashtin, A N; Mitko, G G; Ptitsyn, M O; Ryabov, V A; Shepetov, A L; Shlyugaev, Yu V; Vildanova, L I; Zybin, K P

    2012-03-23

    We report here for the first time about the registration of an extraordinary high flux of low-energy neutrons generated during thunderstorms. The measured neutron count rate enhancements are directly connected with thunderstorm discharges. The low-energy neutron flux value obtained in our work is a challenge for the photonuclear channel of neutron generation in thunderstorm: the estimated value of the needed high-energy γ-ray flux is about 3 orders of magnitude higher than that one observed. PMID:22540588

  13. A FORTRAN-90 Low-Energy Electron Diffraction program (LEED90 v1.1)

    NASA Astrophysics Data System (ADS)

    Blanco-Rey, Maria; de Andres, Pedro; Held, Georg; King, David A.

    2004-08-01

    We describe a FORTRAN-90 program to compute low-energy electron diffraction I(V) curves. Plane-waves and layer doubling are used to compute the inter-layer multiple-scattering, while the intra-layer multiple-scattering is computed in the standard way expanding the wavefield on a basis of spherical waves. The program is kept as general as possible, in order to allow testing different parts of multiple-scattering calculations. In particular, it can handle non-diagonal t-matrices describing the scattering of non-spherical potentials, anisotropic vibrations, anharmonicity, etc. The program does not use old FORTRAN flavours, and has been written keeping in mind the advantage for parallelism brought forward by FORTRAN-90. Program summaryTitle of program: LEED90 Catalogue number: ADUE Program summary URL:http://cpc.sc.qub.ac.uk/summaries/ADUE Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland. Computers: Alpha ev6-21264 (700 MHz) and Pentium-IV. Operating system: Digital UNIX V5.0 and Linux (Red Hat 8.0). Programming language: FORTRAN-90/95 (Compaq True64 compiler, and Intel Fortran Compiler 7.0 for Linux). High-speed storage required for the test run: minimum 64 Mbytes, it can grow to more depending on the system considered. Disk storage required: None No. of bits in a word: 64 and 32 No. of lines in distributed program, including test data, etc.: 17 953 No. of bytes in distributed program, including test data, etc.: 100 051 Distribution format: tar.gz Nature of problem: We describe the FORTRAN-90 program LEED90 (v1.1) to compute dynamical I(V) curves using layer-doubling. The program has been designed to be able to take, as an option, input from non-diagonal t-matrix, e.g., representing a molecule, temperature corrections for anisotropic/anharmonic vibrations, or non-spherical muffin-tin potentials. Method of solution: The intra-layer multiple-scattering problem is solved by adding self-consistently spherical wave amplitudes

  14. Enhanced production of low energy electrons by alpha particle impact.

    PubMed

    Kim, Hong-Keun; Titze, Jasmin; Schöffler, Markus; Trinter, Florian; Waitz, Markus; Voigtsberger, Jörg; Sann, Hendrik; Meckel, Moritz; Stuck, Christian; Lenz, Ute; Odenweller, Matthias; Neumann, Nadine; Schössler, Sven; Ullmann-Pfleger, Klaus; Ulrich, Birte; Fraga, Rui Costa; Petridis, Nikos; Metz, Daniel; Jung, Annika; Grisenti, Robert; Czasch, Achim; Jagutzki, Ottmar; Schmidt, Lothar; Jahnke, Till; Schmidt-Böcking, Horst; Dörner, Reinhard

    2011-07-19

    Radiation damage to living tissue stems not only from primary ionizing particles but to a substantial fraction from the dissociative attachment of secondary electrons with energies below the ionization threshold. We show that the emission yield of those low energy electrons increases dramatically in ion-atom collisions depending on whether or not the target atoms are isolated or embedded in an environment. Only when the atom that has been ionized and excited by the primary particle impact is in immediate proximity of another atom is a fragmentation route known as interatomic Coulombic decay (ICD) enabled. This leads to the emission of a low energy electron. Over the past decade ICD was explored in several experiments following photoionization. Most recent results show its observation even in water clusters. Here we show the quantitative role of ICD for the production of low energy electrons by ion impact, thus approaching a scenario closer to that of radiation damage by alpha particles: We choose ion energies on the maximum of the Bragg peak where energy is most efficiently deposited in tissue. We compare the electron production after colliding He(+) ions on isolated Ne atoms and on Ne dimers (Ne(2)). In the latter case the Ne atom impacted is surrounded by a most simple environment already opening ICD as a deexcitation channel. As a consequence, we find a dramatically enhanced low energy electron yield. The results suggest that ICD may have a significant influence on cell survival after exposure to ionizing radiation.

  15. Low-energy particle radiation environment at synchronous altitude

    NASA Technical Reports Server (NTRS)

    Shelley, E. G.; Lens, S. K.

    1972-01-01

    The degradation of thermal control coatings of satellites due to the effects of low energy charged particles in the space environment is discussed. Data obtained from ATS-5 satellite measurement of proton and electron fluxes are presented. The variations in electron density, proton density, and magnetic activity are presented to show correlations which exist between these space factors.

  16. Effective low-energy theory for superconducting topological insulators.

    PubMed

    Hao, Lei; Lee, Ting-Kuo

    2015-03-18

    Candidate pairings of superconducting topological insulators support interesting surface Andreev bound states (SABSs) known as Majorana fermions. As these materials are described by a two-orbital Bernevig-Hughes-Zhang type model, a general understanding of the low-energy physics such as the possible kinds of SABSs are difficult. By virtue of an analogy between a topological insulator and a time reversal invariant topological superconductor, we propose a simple and intuitive method of constructing the low-energy effective models for superconducting topological insulators like CuxBi2Se3. Depending on the value of the chemical potential and for experimentally relevant model parameters, the low-energy properties of these superconductors are shown to be determined by one copy or two copies of single-orbital effective models. If the effective pairing potential shows sign reversal upon reflection by the surface, one Kramers' pair or two Kramers' pairs of SABSs are expected to appear. Explicit analytical calculations in terms of the effective low energy model reproduce the dispersions of the numerically confirmed two pairs of SABSs for a commonly studied pairing.

  17. MEIC Proton Beam Formation with a Low Energy Linac

    SciTech Connect

    Zhang, Yuhong

    2015-09-01

    The MEIC proton and ion beams are generated, accumulated, accelerated and cooled in a new green-field ion injector complex designed specifically to support its high luminosity goal. This injector consists of sources, a linac and a small booster ring. In this paper we explore feasibility of a short ion linac that injects low-energy protons and ions into the booster ring.

  18. Nuclear phenomena in low-energy nuclear reaction research.

    PubMed

    Krivit, Steven B

    2013-09-01

    This is a comment on Storms E (2010) Status of Cold Fusion, Naturwissenschaften 97:861-881. This comment provides the following remarks to other nuclear phenomena observed in low-energy nuclear reactions aside from helium-4 make significant contributions to the overall energy balance; and normal hydrogen, not just heavy hydrogen, produces excess heat.

  19. HEAO-1 analysis of Low Energy Detectors (LED)

    NASA Technical Reports Server (NTRS)

    Nousek, John A.

    1992-01-01

    The activities at Penn State University are described. During the period Oct. 1990 to Dec. 1991 work on HEAO-1 analysis of the Low Energy Detectors (LED) concentrated on using the improved detector spectral simulation model and fitting diffuse x-ray background spectral data. Spectral fitting results, x-ray point sources, and diffuse x-ray sources are described.

  20. Physics overview of the Fermilab Low Energy Antiproton Facility Workshop

    SciTech Connect

    Chanowitz, M.S.

    1986-05-01

    A physics overview is presented of the Fermilab workshop to consider a possible high flux, low energy antiproton facility that would use cooled antiprotons from the accumulator ring of the Tevatron collider. Two examples illustrate the power of each a facility to produce narrow states at high rates. Physics topics to which such a facility may be applied are reviewed.

  1. Mirrored low-energy channel for the MiniXRD

    NASA Astrophysics Data System (ADS)

    Dutra, E. C.; MacNeil, L. P.; Compton, S. M.; Jacoby, B. A.; Raphaelian, M. L.

    2015-08-01

    X-ray Diodes (XRDs) are currently used for spectroscopic measurements, measuring X-ray flux, and estimating spectral shape of the VUV to soft X-ray spectrum. A niche exists for an inexpensive, robust X-ray diode that can be used for experiments in hostile environments on multiple platforms, including explosively driven experiments that have the potential for destroying the diode during the experiment. A multiple channel stacked filtered array was developed with a small field of view where a wider parallel array could not be used, but filtered channels for energies lower than 1000 eV were too fragile to deploy under normal conditions. To achieve both the robustness and the required low-energy detection ability, we designed a small low-energy mirrored channel with a spectral sensitivity from 30 to 1000 eV. The stacked MiniXRD X-ray diode system design incorporates the mirrored low-energy channel on the front of the stacked filtered channels to allow the system to work within a small field of view. We will present results that demonstrate this is a promising solution for low-energy spectrum measurements.

  2. Low-energy d-d excitations in MnO studied by resonant x-ray fluorescence spectroscopy

    SciTech Connect

    Butorin, S.M.; Guo, J.; Magnuson, M.

    1997-04-01

    Resonant soft X-ray emission spectroscopy has been demonstrated to possess interesting abilities for studies of electronic structure in various systems, such as symmetry probing, alignment and polarization dependence, sensitivity to channel interference, etc. In the present abstract the authors focus on the feasibility of resonant soft X-ray emission to probe low energy excitations by means of resonant electronic X-ray Raman scattering. Resonant X-ray emission can be regarded as an inelastic scattering process where a system in the ground state is transferred to a low excited state via a virtual core excitation. The energy closeness to a core excitation of the exciting radiation enhances the (generally) low probability for inelastic scattering at these wavelengths. Therefore soft X-ray emission spectroscopy (in resonant electronic Raman mode) can be used to study low energy d-d excitations in transition metal systems. The involvement of the intermediate core state allows one to use the selection rules of X-ray emission, and the appearance of the elastically scattered line in the spectra provides the reference to the ground state.

  3. Numerical simulations for width fluctuations in compound elastic and inelastic scattering at low energies

    SciTech Connect

    Kawano, Toshihiko; Talou, Patrick

    2012-09-18

    The statistical theories - the Hauser-Feshbach model with the width fluctuation correction - play a central role in studying nuclear reactions in the fast energy region, hence the statistical model codes are essential for the nuclear data evaluations nowadays. In this paper, we revisit issues regarding the statistical model calculations in the fast energy range, such as the inclusion of the direct channels, and the energy averaged cross sections using different statistical assumptions. Although they have been discussed for a long time, we need more precise quantitative investigations to understand uncertainties coming from the models deficiencies in the fast energy range. For example, the partition of compound formation cross section into the elastic and inelastic channels depends on the elastic enhancement factor calculated from the statistical models. In addition, unitarity of S-matrix constrains this partition when the direct reactions are involved. Practically some simple assumptions, which many nuclear reaction model codes adopt, may work reasonably for the nuclear data evaluations. However, the uncertainties on the evaluated cross sections cannot go lower than the model uncertainty itself. We perform numerical simulations by generating the resonances using the R-matrix theory, and compare the energy (ensemble) averaged cross sections with the statistical theories, such as the theories of Moldauer, HRTW (Hofmann, Richert, Tepel, and Weidenmueller), KKM (Kawai-Kerman-McVoy), and GOE (Gaussian orthogonal ensemble).

  4. Low-energy outer-shell photodetachment of the negative ion of boron

    NASA Astrophysics Data System (ADS)

    Wang, Kedong; Zatsarinny, Oleg; Bartschat, Klaus

    2016-04-01

    The photodetachment of the negative ion of boron, B-(2s22p2)3P, is investigated by employing the B-spline R-matrixmethod for photon energies ranging from threshold to 12 eV. A multi-configuration Hartree-Fock method with nonorthogonal, term-dependent orbitals is employed to generate accurate initial bound-state and final continuum-state wavefunctions. The close-coupling expansion includes all principal scattering channels for photodetachment from both the 2p and 2s orbitals. The calculated photodetachment cross sections are in good agreement with the available experimental data. Several prominent resonance features are predicted, thereby providing new challenges in the study of this highly correlated process. To classify the resonance structure, both the partial cross sections and the main contributions of the individual scattering channels are discussed. The presented cross sections, along with the asymmetry parameter β for the angular distribution, are believed to be the most comprehensive and accurate dataset currently available for the B- photodetachment process at low energies. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  5. Transmission of low energy (< 10 eV) oxygen ions through ultrathin xenon films

    NASA Astrophysics Data System (ADS)

    Sack, N. J.; Akbulut, M.; Madey, T. E.

    1994-05-01

    In studies of desorption induced by electronic transitions (DIET) such as electron or photon stimulated desorption, it is important to know whether the desorbing species originate solely from the outermost surface layer, or also from layers beneath the surface. In order to gain better understanding of the charge transfer, elastic scattering, and other inelastic processes involved in this issue, we are currently performing a series of experimental studies of the transmission of low energy ions (˜ 7 eV) through ultrathin films (submonolayer to multilayer) of condensed gases. Here we report on the first quantitative measurements of the yield, angle, and energy of oxygen ions after transmission through ultrathin films of xenon. In our novel approach, a focused 300 eV electron beam bombards a target at 25 K consisting of an oxidized tungsten (100) crystal with adsorbed overlayers of xenon. In the absence of the xenon, O + ions desorb in a sharp beam normal to the surface, as measured in a velocity and angle resolving ESDIAD apparatus (electron stimulated desorption ion angular distribution). When Xe layers are present, some oxygen ions penetrate several monolayers of xenon without significant change in energy and angle while others seem to be scattered by large-angle elastic scattering or to be attenuated from the O + beam. The work presented is the first experimental study of the depth of origin of desorbing ions in DIET processes.

  6. Low-energy universality and scaling of van der Waals forces

    SciTech Connect

    Calle Cordon, A.; Ruiz Arriola, E.

    2010-04-15

    At long distances, interactions between neutral ground-state atoms can be described by the van der Waals potential. In the ultracold regime, atom-atom scattering is dominated by s-waves phase shifts given by an effective range expansion in terms of the scattering length {alpha}{sub 0} and the effective range r{sub 0}. We show that while the scattering length cannot be predicted for these potentials, the effective range is given by the universal low-energy theorem r{sub 0}=A+B/{alpha}{sub 0}+C/{alpha}{sub 0}{sup 2}, where A, B, and C depend on the dispersion coefficients C{sub n} and the reduced diatom mass. We confront this formula to about 100 determinations of r{sub 0} and {alpha}{sub 0} and show why the result is dominated by the leading dispersion coefficient C{sub 6}. Universality and scaling extend much beyond naive dimensional analysis estimates.

  7. ELENA MCP detector: absolute detection efficiency for low-energy neutral atoms

    NASA Astrophysics Data System (ADS)

    Rispoli, R.; De Angelis, E.; Colasanti, L.; Vertolli, N.; Orsini, S.; Scheer, J. A.; Mura, A.; Milillo, A.; Wurz, P.; Selci, S.; Di Lellis, A. M.; Leoni, R.; D'Alessandro, M.; Mattioli, F.; Cibella, S.

    2012-09-01

    Microchannel Plates (MCP) detectors are frequently used in space instrumentation for detecting a wide range of radiation and particles. In particular, the capability to detect non-thermal low energy neutral species is crucial for the sensor ELENA (Emitted Low-Energy Neutral Atoms), part of the package SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) on board the BepiColombo mission of ESA to Mercury to be launched in 2015. ELENA is a Time of Flight (TOF) sensor, based on a novel concept using an ultra-sonic oscillating shutter (Start section), which is operated at frequencies up to 50 kHz; a MCP detector is used as a Stop detector. The scientific objective of ELENA is to detect energetic neutral atoms in the range 10 eV - 5 keV, within 76° FOV, perpendicular to the S/C orbital plane. ELENA will monitor the emission of neutral atoms from the whole surface of Mercury thanks to the spacecraft motion. The major scientific objectives are the interaction between the plasma environment and the planet’s surface, the global particle loss-rate and the remote sensing of the surface properties. In particular, surface release processes are investigated by identifying particles released from the surface, via solar wind-induced ion sputtering (< 1eV - < 100 eV) as well as Hydrogen back-scattered at hundreds eV. MCP absolute detection efficiency for very low energy neutral atoms (E < 30 eV) is a crucial point for this investigation. At the MEFISTO facility of the Physical Institute of the University of Bern (CH), measurements on three different types of MCP (with and without coating) have been performed providing the detection efficiencies in the energy range 10eV - 1keV. Outcomes from such measurements are discussed here.

  8. ELENA MCP detector: absolute efficiency measurement for low energy neutral atoms

    NASA Astrophysics Data System (ADS)

    Rispoli, R.; De Angelis, E.; Colasanti, L.; Vertolli, N.; Orsini, S.; Scheer, J.; Mura, A.; Milillo, A.; Wurz, P.; Selci, S.; Di Lellis, A. M.; Leoni, R.; D'Alessandro, M.; Mattioli, F.; Cibella, S.

    2012-04-01

    MicroChannel plates (MCP) detectors are frequently used in space instrumentation for detecting a wide range of radiation and particles. In particular, the capability to detect non-thermal low energy neutral species is crucial for the sensor ELENA (Emitted Low-Energy Neutral Atoms), part of the package SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) on board the BepiColombo mission to Mercury to be launched in 2014. ELENA is a TOF sensor, based on a novel concept ultra-sonic oscillating shutter (Start section)which is operated at frequencies up to 50 kHz; a MCP detector is used as a Stop section. It is aimed to detect neutral atoms in the range 10 eV - 5 keV, within 70° FOV, perpendicular to the S/C orbital plane. ELENA will monitor the emission of neutral atoms from the whole surface of Mercury thanks to the spacecraft motion. The major scientific objectives are the interaction between the environment and the planet, the global particle loss-rate and the remote sensing of the surface properties. In particular, surface release processes are investigated by identifying particles release from the surface, via solar wind-induced ion sputtering (<1eV and >100 eV) as well as Hydrogen back-scattered at hundreds eV. MCP absolute detection efficiency for very low energy neutral atoms (E< 30eV) is a crucial point not yet investigated. At the MEFISTO facility of the Physical Institute of University of Bern (CH), measurements on three different type of MCPs coating have been performed providing the behaviors of MCP detection efficiency in the range 10eV-1keV. Outcomes from such measurements are here discussed.

  9. Staggered magnetization and low-energy magnon dispersion in the multiferroic skyrmion host Cu2OSeO3

    NASA Astrophysics Data System (ADS)

    Marcus, Guy G.; Trump, Benjamin A.; Kindervater, Jonas; Jones, Lacy L.; Stone, Matthew B.; McQueen, Tyrel M.; Broholm, Collin L.

    We present neutron diffraction and inelastic scattering of the insulating helimagnet, Cu2OSeO3 which provide evidence for staggered magnetization and elucidate the associated low-energy magnon spectrum. The modulation wavelength of approximately λ ~ 50 nm detected at antiferromagnetic Bragg points is of the same length scale as previously reported for the skyrmion lattice. This superstructure evidences the composite nature of the spin-1 tetrahedra that form the topological magnetic structure of the material. To understand the interplay of ferrimagnetism and long wavelength modulated magnetism, we have performed inelastic neutron scattering on a co-aligned sample of chemical vapor transport grown single crystals. We shall present the low-energy magnon dispersion and infer an effective spin Hamiltonian to account for the long-wavelength, low-energy magnetism of Cu2OSeO3. The work at IQM was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Material Sciences and Engineering, under Grant No. DEFG02-08ER46544. GGM also acknowledges support from the NSF-GRFP Grant No. DGE-1232825.

  10. Measuring Neutron-Proton Radiative Capture Cross-section at Low Energy

    NASA Astrophysics Data System (ADS)

    Yu, To Chin; Kovash, Michael; Matthews, June; Yang, Hongwei; Yang, Yunjie

    2015-10-01

    The experiment aims to fill in a gap in our data for the cross-section of neutron-proton radiative capture (p(n,d γ)) at energies below 500 keV. Current measurements in this energy range are scarce and inconsistent with theoretical predictions and with each other. A well-determined cross-section of the capture reaction in the low energy range is useful in nuclear physics due to its fundamental nature. The measurement is also of interest in cosmology. Big Bang Nucleosynthesis (BBN), the process by which light elements are formed in early universe, is very sensitive to the p(n,d γ) cross-section in the low energy range. The measurement enables us to put tighter constraints on the theoretical predictions of BBN. We have conducted preliminary measurements in the van de Graaff accelerator facility at the University of Kentucky. Our array of detectors consists of three plastic scintillators to serve as proton targets and deuteron detectors, and five BGO scintillators to detect γ-rays. The combination results in an over-determination of reaction kinematics that discriminates against scattering processes and other backgrounds. We have obtained some early results which show promise for the precise measurement of the p(n,d γ) cross-section.

  11. Study of Nuclear Structure of 13C and 20Ne by Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Lombardo, I.; Campajola, L.; Dell'Aquila, D.; La Commara, M.; Ordine, A.; Rosato, E.; Spadaccini, G.; Vigilante, M.

    2014-12-01

    We report some recent experimental results on the spectroscopy of 13C and 20Ne nuclei by means of low energy nuclear reactions carried out with high resolution electrostatic accelerators. In the case of 13C we investigated the possible existence of a-cluster states above the a emission threshold by means of low energy elastic resonant scattering α+9Be in direct kinematics. Excitation functions show the presence of various resonances that have been reproduced by R-matrix fit. We studied also the structure of 20Ne by means of the 19F(p,α0) reaction at sub-barrier energies. The spectroscopy of 20Ne excited states in the region Ex ≈ 13.5-14.0 MeV can be probed by analyzing experimental angular distributions and excitation functions. This reaction plays an important role also in the CNOF cycle and is an important ingredient to describe hydrogen-induced destruction of fluorine in massive stars. For this reason we investigated the trend of S-factor, that has been compared with results previously reported in the literature.

  12. Modeling ionization and recombination from low energy nuclear recoils in liquid argon

    NASA Astrophysics Data System (ADS)

    Foxe, M.; Hagmann, C.; Jovanovic, I.; Bernstein, A.; Joshi, T. H.; Kazkaz, K.; Mozin, V.; Pereverzev, S. V.; Sangiorgio, S.; Sorensen, P.

    2015-09-01

    Coherent elastic neutrino-nucleus scattering (CENNS) is an as-yet undetected, flavor-independent neutrino interaction predicted by the Standard Model. Detection of CENNS could offer benefits for detection of supernova and solar neutrinos in astrophysics, or for detection of antineutrinos for nuclear reactor monitoring and nuclear nonproliferation. One challenge with detecting CENNS is the low energy deposition associated with a typical CENNS nuclear recoil. In addition, nuclear recoils result in lower ionization yields than those produced by electron recoils of the same energy. While a measurement of the nuclear recoil ionization yield in liquid argon in the keV energy range has been recently reported, a corresponding model for low-energy ionization yield in liquid argon does not exist. For this reason, a Monte Carlo simulation has been developed to predict the ionization yield at sub-10 keV energies. The model consists of two distinct components: (1) simulation of the atomic collision cascade with production of ionization, and (2) the thermalization and drift of ionization electrons in an applied electric field including local recombination. As an application of our results we report updated estimates of detectable ionization in liquid argon from CENNS at a nuclear reactor.

  13. Extending ion-track lithography to the low-energy ion regime

    SciTech Connect

    Musket, R G

    2005-10-14

    Ion tracking and ion-track lithography have been performed almost exclusively using ions with energies near or above the maximum in electronic stopping, which occurs at {approx}1 MeV/amu. In this paper, ion-track lithography using ions with energies well below this maximum is discussed. The results of etching ion tracks created in polycarbonate films by ions with energies just above the anticipated threshold for creating etchable latent tracks with cylindrical geometry have been examined. Low-energy neon and argon ions with 18-60 keV/amu and fluences of {approx}10{sup 8}/cm{sup 2} were used to examine the limits for producing useful, etchable tracks in polycarbonate films. By concentrating on the early stages of etching (i.e., {approx}20 nm < SEM hole diameter < {approx}100 nm), the energy deposition calculated for the incident ion was correlated with the creation of etchable tracks. The experimental results are discussed with regard to the energy losses of the ions in the polycarbonate films and to the formation of continuous latent tracks through the entire thickness of the films. The probability distributions for large-angle scattering events were calculated to assess their importance as a function of ion energy. All these results have significant implications with respect to the threshold for formation of etchable tracks and to the use of low-energy ions for lithographic applications of ion tracking.

  14. Extending ion-track lithography to the low-energy ion regime

    SciTech Connect

    Musket, R.G.

    2006-06-01

    Ion tracking and ion-track lithography have been performed almost exclusively using ions with energies near or above the maximum in electronic stopping, which occurs at {approx}1 MeV/amu. In this paper, ion-track lithography using ions with energies well below this maximum is discussed. The results of etching ion tracks created in polycarbonate films by ions with energies just above the anticipated threshold for creating etchable latent tracks with cylindrical geometry have been examined. Low-energy neon and argon ions with 18-60 keV/amu and fluences of {approx}10{sup 8} cm{sup -2} were used to examine the limits for producing useful, etchable tracks in polycarbonate films. By concentrating on the early stages of etching (i.e., {approx}20 nmscattering events were calculated to assess their importance as a function of ion energy. All these results have significant implications with respect to the threshold for formation of etchable tracks and to the use of low-energy ions for lithographic applications of ion tracking.

  15. Excitation of the lowest electronic transitions in ethanol by low-energy electrons

    NASA Astrophysics Data System (ADS)

    Hargreaves, L. R.; Khakoo, M. A.; Winstead, C.; McKoy, V.

    2016-09-01

    We report absolute differential and integral cross sections for electronic excitation of ethanol, by low-energy electron impact. Cross sections for low-lying excited states were measured at incident electron energies from 9 to 20 eV and at scattering angles from {5}\\circ through {130}\\circ . Our results include cross sections for excitation of the 1{}3A\\prime \\prime and 1{}1A\\prime \\prime states as well as for the 2{}3A\\prime \\prime + 1{}3A\\prime and 2{}1A\\prime \\prime + 2{}1A\\prime cross section sums. Corresponding calculations were also performed using the Schwinger multichannel method, within an 11-channel close-coupling scheme.

  16. Low energy properties of the Kondo chain in the RKKY regime

    DOE PAGES

    D. H. Schimmel; Tsvelik, A. M.; Yevtushenko, O. M.

    2016-05-03

    We study the Kondo chain in the regime of high spin concentration where the low energy physics is dominated by the Ruderman–Kittel–Kasuya–Yosida interaction. As has been recently shown (Tsvelik and Yevtushenko 2015 Phys. Rev. Lett. 115 216402), this model has two phases with drastically different transport properties depending on the anisotropy of the exchange interaction. In particular, the helical symmetry of the fermions is spontaneously broken when the anisotropy is of the easy plane type. This leads to a parametrical suppression of the localization effects. In the present paper we substantially extend the previous theory, in particular, by analyzing amore » competition of forward- and backward- scattering, including into the theory short range electron interactions and calculating spin correlation functions. In conclusion, we discuss applicability of our theory and possible experiments which could support the theoretical findings.« less

  17. Nuclear Astrophysical studies using low-energy RI beams at CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Wakabayashi, Y.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kurihara, Y.; Kubono, S.; Teranishi, T.; He, J. J.; Kwon, Y. K.; Nishimura, S.; Togano, Y.; Iwasa, N.; Niikura, M.; Khiem, L. H.

    2009-05-01

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo, used for various studies covering nuclear-astrophysical topics. An application of the RI beam at CRIB for the astrophysical studies is a new measurement of the proton resonance scattering on 7Be. The measurement was performed up to the excitation energy of 6.8 MeV, ans the excitation function above 3.5 MeV was successfully measured for the first time, providing important information about the reaction rate of 7Be(p,γ)8B, which is the key reaction in the solar 8B neutrino production. A preliminary result of the 7Be+p experiment is presented.

  18. The weak mixing angle from low energy neutrino measurements: A global update

    NASA Astrophysics Data System (ADS)

    Cañas, B. C.; Garcés, E. A.; Miranda, O. G.; Tórtola, M.; Valle, J. W. F.

    2016-10-01

    Taking into account recent theoretical and experimental inputs on reactor fluxes we reconsider the determination of the weak mixing angle from low energy experiments. We perform a global analysis to all available neutrino-electron scattering data from reactor antineutrino experiments, obtaining sin2 ⁡θW = 0.252 ± 0.030. We discuss the impact of the new theoretical prediction for the neutrino spectrum, the new measurement of the reactor antineutrino spectrum by the Daya Bay collaboration, as well as the effect of radiative corrections. We also reanalyze the measurements of the νe - e cross section at accelerator experiments including radiative corrections. By combining reactor and accelerator data we obtain an improved determination for the weak mixing angle, sin2 ⁡θW = 0.254 ± 0.024.

  19. Nuclear Astrophysical studies using low-energy RI beams at CRIB

    SciTech Connect

    Yamaguchi, H.; Wakabayashi, Y.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kurihara, Y.; Kubono, S.; Niikura, M.; Teranishi, T.; He, J. J.; Kwon, Y. K.; Nishimura, S.; Togano, Y.; Iwasa, N.; Khiem, L. H.

    2009-05-04

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo, used for various studies covering nuclear-astrophysical topics. An application of the RI beam at CRIB for the astrophysical studies is a new measurement of the proton resonance scattering on {sup 7}Be. The measurement was performed up to the excitation energy of 6.8 MeV, ans the excitation function above 3.5 MeV was successfully measured for the first time, providing important information about the reaction rate of {sup 7}Be(p,{gamma}){sup 8}B, which is the key reaction in the solar {sup 8}B neutrino production. A preliminary result of the {sup 7}Be+p experiment is presented.

  20. Low energy properties of the Kondo chain in the RKKY regime

    NASA Astrophysics Data System (ADS)

    Schimmel, D. H.; Tsvelik, A. M.; Yevtushenko, O. M.

    2016-05-01

    We study the Kondo chain in the regime of high spin concentration where the low energy physics is dominated by the Ruderman-Kittel-Kasuya-Yosida interaction. As has been recently shown (Tsvelik and Yevtushenko 2015 Phys. Rev. Lett. 115 216402), this model has two phases with drastically different transport properties depending on the anisotropy of the exchange interaction. In particular, the helical symmetry of the fermions is spontaneously broken when the anisotropy is of the easy plane type. This leads to a parametrical suppression of the localization effects. In the present paper we substantially extend the previous theory, in particular, by analyzing a competition of forward- and backward- scattering, including into the theory short range electron interactions and calculating spin correlation functions. We discuss applicability of our theory and possible experiments which could support the theoretical findings.

  1. A New Apparatus for Studies of Low Energy Electron Collisions with Nucleotide Molecules

    NASA Astrophysics Data System (ADS)

    Duron, Jessica; Hargreaves, Leigh

    Low-energy electrons, the most copiously produced by-product of radiation cancer therapy, have been shown to be a strong driver of DNA damage in living cells [1]. Quantitative data describing these collisions are presently rare due to technological challenges in performing electron scattering measurements from the nucleobases, e.g. uracil, thymine, guanine, etc. These challenges include the low-vapor pressure of commercial samples (which are powders at room temperature), and the difficulty in making accurate flow measurements from heated gas sources, required to establish the absolute scale of the measured data. Based on techniques pioneered in positron collision physics [2], a new apparatus is presently undergoing commissioning at the California State University Fullerton, which aims to address these issues. We will make the first cross-section measurements for slow (E0 < 30eV) electron collisions with nucleotides. We will report design parameters and ongoing progress in the commissioning of this new experiment.

  2. Low energy dynamics of slender monopoles in non-Abelian superconductor

    NASA Astrophysics Data System (ADS)

    Arai, M.; Blaschke, F.; Eto, M.; Sakai, N.

    2016-01-01

    Low energy dynamics of magnetic monopoles and anti-monopoles in the U(2)c gauge theory is studied in the Higgs (non-Abelian superconducting) phase. The monopoles in this phase are slender ellipsoids, pierced by a vortex string. We investigate scattering of monopole with anti-monopole and find that they do not always decay into radiation, contrary to our naive intuition. They can repel, make bound states (magnetic mesons) or resonances. We point out that some part of solutions in 1 + 3 dimensions can be mapped exactly onto the sine-Gordon system in 1 + 1 dimensions in the first non-trivial order of rigid-body approximation and we provide analytic formulas for such solutions there.

  3. A New Polyethylene Scattering Law Determined Using Inelastic Neutron Scattering

    SciTech Connect

    Lavelle, Christopher M; Liu, C; Stone, Matthew B

    2013-01-01

    Monte Carlo neutron transport codes such as MCNP rely on accurate data for nuclear physics cross-sections to produce accurate results. At low energy, this takes the form of scattering laws based on the dynamic structure factor, S (Q, E). High density polyethylene (HDPE) is frequently employed as a neutron moderator at both high and low temperatures, however the only cross-sections available are for T =300 K, and the evaluation has not been updated in quite some time. In this paper we describe inelastic neutron scattering measurements on HDPE at 5 and 300 K which are used to improve the scattering law for HDPE. We describe the experimental methods, review some of the past HDPE scattering laws, and compare computations using these models to the measured S (Q, E). The total cross-section is compared to available data, and the treatment of the carbon secondary scatterer as a free gas is assessed. We also discuss the use of the measurement itself as a scattering law via the 1 phonon approximation. We show that a scattering law computed using a more detailed model for the Generalized Density of States (GDOS) compares more favorably to this experiment, suggesting that inelastic neutron scattering can play an important role in both the development and validation of new scattering laws for Monte Carlo work.

  4. Si etching with reactive neutral beams of very low energy

    SciTech Connect

    Hara, Yasuhiro; Hamagaki, Manabu; Mise, Takaya; Iwata, Naotaka; Hara, Tamio

    2014-12-14

    A Si etching process has been investigated with reactive neutral beams (NBs) extracted using a low acceleration voltage of less than 100 V from CF{sub 4} and Ar mixed plasmas. The etched Si profile shows that the etching process is predominantly anisotropic. The reactive NB has a constant Si etching rate in the acceleration voltage range from 20 V to 80 V. It is considered that low-energy NBs can trigger Si etching because F radicals adsorb onto the Si surface and weaken Si–Si bonds. The etching rate per unit beam flux is 33 times higher than that with Ar NB. These results show that the low-energy reactive NB is useful for damage-free high speed Si etching.

  5. Steering continuum electron dynamics by low-energy attosecond streaking

    NASA Astrophysics Data System (ADS)

    Geng, Ji-Wei; Xiong, Wei-Hao; Xiao, Xiang-Ru; Gong, Qihuang; Peng, Liang-You

    2016-08-01

    A semiclassical model is developed to understand the electronic dynamics in the low-energy attosecond streaking. Under a relatively strong infrared (IR) pulse, the low-energy part of photoelectrons initialized by a single attosecond pulse (SAP) can either rescatter with the ionic core and induce interferences structures in the momentum spectra of the ionized electrons or be recaptured into the Rydberg states. The Coulomb potential plays essential roles in both the electron rescattering and recapturing processes. We find that by changing the time delay between the SAP and the IR pulse, the photoelectrons yield or the population of the Rydberg states can be effectively controlled. The present study demonstrates a fascinating way to steer the electron motion in the continuum.

  6. HIGH POWER OPERATIONS AT THE LOW ENERGY DEMONSTRATION ACCELERATOR (LEDA)

    SciTech Connect

    M. DURAN; V. R. HARRIS

    2001-01-01

    Recently, the Low-Energy Demonstration Accelerator (LEDA) portion of the Accelerator Production of Tritium (APT) project reached its 100-mA, 8-hr continuous wave (CW) beam operation milestone. The LEDA accelerator is a prototype of the low-energy front-end of the linear accelerator (linac) that would have been used in an APT plant. LEDA consists of a 75-keV proton injector, 6.7-MeV, 350-MHz CW radio-frequency quadrupole (RFQ) with associated high-power and low-level RF systems, a short high-energy beam transport (HEBT) and high-power (670-kW CW) beam dump. Details of the LEDA design features will be discussed along with the operational health physics experiences that occurred during the LEDA commissioning phase.

  7. Surface modification using low energy ground state ion beams

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor); Hecht, Michael H. (Inventor); Orient, Otto J. (Inventor)

    1990-01-01

    A method of effecting modifications at the surfaces of materials using low energy ion beams of known quantum state, purity, flux, and energy is presented. The ion beam is obtained by bombarding ion-generating molecules with electrons which are also at low energy. The electrons used to bombard the ion generating molecules are separated from the ions thus obtained and the ion beam is directed at the material surface to be modified. Depending on the type of ion generating molecules used, different ions can be obtained for different types of surface modifications such as oxidation and diamond film formation. One area of application is in the manufacture of semiconductor devices from semiconductor wafers.

  8. Three dimensional calculation of flux of low energy atmospheric neutrinos

    NASA Technical Reports Server (NTRS)

    Lee, H.; Bludman, S. A.

    1985-01-01

    Results of three-dimensional Monte Carlo calculation of low energy flux of atmospheric neutrinos are presented and compared with earlier one-dimensional calculations 1,2 valid at higher neutrino energies. These low energy neutrinos are the atmospheric background in searching for neutrinos from astrophysical sources. Primary cosmic rays produce the neutrino flux peaking at near E sub=40 MeV and neutrino intensity peaking near E sub v=100 MeV. Because such neutrinos typically deviate by 20 approximately 30 from the primary cosmic ray direction, three-dimensional effects are important for the search of atmospheric neutrinos. Nevertheless, the background of these atmospheric neutrinos is negligible for the detection of solar and supernova neutrinos.

  9. Low-Energy Dynamics in Ultradegenerate QCD Matter

    SciTech Connect

    Schaefer, Thomas; Schwenzer, Kai

    2006-09-01

    We study the low-energy behavior of QCD Green functions in the limit that the baryon chemical potential is much larger than the QCD scale parameter {lambda}{sub QCD}. We show that there is a systematic low-energy expansion in powers of ({omega}/m){sup 1/3}, where {omega} is the energy and m is the screening scale. This expansion is valid even if the effective quark-gluon coupling g is not small. The expansion is purely perturbative in the magnetic regime vertical bar k(vector sign) vertical bar >>k{sub 0}. If the external momenta and energies satisfy vertical bar k(vector sign) vertical bar ={approx}k{sub 0}, planar, Abelian ladder diagrams involving the full quark propagator have to be resummed but the corresponding Dyson-Schwinger equations are closed.

  10. Polarimeter for Low Energy X-ray Astrophysical Sources (PLEXAS)

    NASA Technical Reports Server (NTRS)

    Murray, Stephen S.; Pierce, David L. (Technical Monitor)

    2002-01-01

    The Polarimeter for Low Energy X-ray Astrophysical Sources (PLEXAS) is an astrophysics mission concept for measuring the polarization of X-ray sources at low energies below the C-K band (less than 277 eV). PLEXAS uses the concept of variations in the reflectivity of a multilayered X-ray telescope as a function of the orientation of an X-rays polarization vector with respect to the reflecting surface of the optic. By selecting an appropriate multilayer, and rotating the X-ray telescope while pointing to a source, there will be a modulation in the source intensity, as measured at the focus of the telescope, which is proportional to the degree of polarization in the source.

  11. Low-Energy Electron Beam Direct Writing Equipment

    NASA Astrophysics Data System (ADS)

    Fuse, Takashi; Ando, Atsushi; Kotsugi, Tadashi; Kinoshita, Hidetoshi; Sugihara, Kazuyoshi

    2007-09-01

    We proposed an electron beam direct writing (EBDW) system capable of high throughput and maskless operation based on a novel concept of using both low-energy electron beam (EB) and character projection (CP) system. We fabricated an EB optical column of low-energy EBDW equipment and obtained a resist pattern. We also investigated the beam blur and line width roughness (LWR) of lines and spaces (L/S) formed on a resist to change various EB current densities and convergence half angles. The obtained results show that a Coulomb interaction effect markedly affects the beam blur in our EB optical column. Thus, we reduce the number of sources caused by LWR and developed photoresists to obtain small LWR L/S patterns for achieving a high throughput.

  12. Semiconductor detector performance for low-energy x-rays

    SciTech Connect

    Jaklevic, J.M.; Walton, J.T.; McMurray, R.E. Jr.; Madden, N.W.; Goulding, F.S.

    1987-06-01

    Factors that limit the capabilities of semiconductor detectors at photon energies below 5 keV include energy resolution, detector efficiency, and detector-related continuum background. These properties can be controlled to a certain extent by optimal detector design and fabrication techniques. We describe measurements on the low-energy response of Si(Li) detectors obtained using a tunable, low-energy monochromatic source. Window thicknesses have been measured for a number of devices using different materials for the entry contact. The interpretation of these results in terms of existing detector window models is discussed. Results obtained using a new contact structure demonstrate that a dramatic reduction in window-related absorption in Si(Li) detectors can be achieved.

  13. Status of the Frankfurt low energy electrostatic storage ring (FLSR)

    NASA Astrophysics Data System (ADS)

    King, F.; Kruppi, T.; Müller, J.; Dörner, R.; Schmidt, L. Ph H.; Schmidt-Böcking, H.; Stiebing, K. E.

    2015-11-01

    Frankfurt low-energy storage ring (FLSR) is an electrostatic storage ring for low-energy ions up to q · 80 keV (q being the ion charge state) at Institut für Kernphysik der Goethe-Universität, Frankfurt am Main, Germany. It has especially been designed to provide a basis for experiments on the dynamics of ionic and molecular collisions in complete kinematics, as well as for high precision and time resolved laser spectroscopy. The ring has ‘racetrack’ geometry with a circumference of 14.23 m. It comprises four experimental/diagnostic sections with regions of enhanced ion density (interaction regions). First beam has successfully been stored in FLSR in summer 2013. Since then the performance of the ring has continuously been improved and an electron target for experiments on dissociative recombination has been installed in one of the experimental sections.

  14. Developments in low energy electron beam machinery and processes

    NASA Astrophysics Data System (ADS)

    Nablo, S. V.; Chrusciel, J.; Cleghorn, D. A.; Rangwalla, I.

    2003-08-01

    The engineering and development of a new generation of low energy, high power electron beam equipment is presented. Operating voltages range from 80 to 125 kV at widths to 1.65 m. At 110 kV these systems deliver 1000 Mrad m min -1 at 110 kV. Equipment operating power levels and their impact on reducing equipment size and cost are reviewed. The advantages of electron curing at these reduced operating voltages are described. The principles of the electron beam fluidized bed process for the treatment of powders and particulates in high-speed pneumatic transport are discussed. Typical system performances for polymer dissociation and crosslinking, or for agroproduct disinfestation and disinfection are presented. A process for the sterilization of polymer food containers employing the injection of low energy electrons through the open mouth has been developed. Some of its sterilization capabilities for bottles up to 2 l capacity are described.

  15. Pin diode calibration - beam overlap monitoring for low energy cooling

    SciTech Connect

    Drees, A.; Montag, C.; Thieberger, P.

    2015-09-30

    We were trying to address the question whether or not the Pin Diodes, currently installed approximately 1 meter downstream of the RHIC primary collimators, are suitable to monitor a recombination signal from the future RHIC low energy cooling section. A maximized recombination signal, with the Au+78 ions being lost on the collimator, will indicate optimal Au-electron beam overlap as well as velocity matching of the electron beam in the cooling section.

  16. Photon Strength Function at Low Energies in 95Mo

    NASA Astrophysics Data System (ADS)

    Wiedeking, M.; Bernstein, L. A.; Allmond, J. M.; Basunia, M. S.; Bleuel, D. L.; Burke, J. T.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Krtička, M.; Lake, P. T.; Larsen, A. C.; Lee, I.-Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.

    2014-05-01

    A new and model-independent experimental method has been developed to determine the energy dependence of the photon strength function. It is designed to study statistical feeding from the quasi continuum to individual low-lying discrete levels. This new technique is presented and results for 95Mo are compared to data from the University of Oslo. In particular, questions regarding the existence of the low-energy enhancement in the photon strength function are addressed.

  17. Surface conversion techniques for low energy neutral atom imagers

    NASA Technical Reports Server (NTRS)

    Quinn, J. M.

    1995-01-01

    This investigation has focused on development of key technology elements for low energy neutral atom imaging. More specifically, we have investigated the conversion of low energy neutral atoms to negatively charged ions upon reflection from specially prepared surfaces. This 'surface conversion' technique appears to offer a unique capability of detecting, and thus imaging, neutral atoms at energies of 0.01 - 1 keV with high enough efficiencies to make practical its application to low energy neutral atom imaging in space. Such imaging offers the opportunity to obtain the first instantaneous global maps of macroscopic plasma features and their temporal variation. Through previous in situ plasma measurements, we have a statistical picture of large scale morphology and local measurements of dynamic processes. However, with in situ techniques it is impossible to characterize or understand many of the global plasma transport and energization processes. A series of global plasma images would greatly advance our understanding of these processes and would provide the context for interpreting previous and future in situ measurements. Fast neutral atoms, created from ions that are neutralized in collisions with exospheric neutrals, offer the means for remotely imaging plasma populations. Energy and mass analysis of these neutrals provides critical information about the source plasma distribution. The flux of neutral atoms available for imaging depends upon a convolution of the ambient plasma distribution with the charge exchange cross section for the background neutral population. Some of the highest signals are at relatively low energies (well below 1 keV). This energy range also includes some of the most important plasma populations to be imaged, for example the base of the cleft ion fountain.

  18. Overview of Light Hydrogen-Based Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Miley, George H.; Shrestha, Prajakti J.

    This paper reviews light water and hydrogen-based low-energy nuclear reactions (LENRs) including the different methodologies used to study these reactions and the results obtained. Reports of excess heat production, transmutation reactions, and nuclear radiation emission are cited. An aim of this review is to present a summary of the present status of light water LENR research and provide some insight into where this research is heading.

  19. Low-energy gamma rays from Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Roques, J. P.; Mandrou, P.; Lebrun, F.; Paul, J.

    1985-01-01

    The Cyg X-1 was observed by the balloonborne telescope OPALE, in June 1976. The high energy spectrum of the source, which was in its superlow state, was seen to extend well beyond 1 MeV. The observed low energy gamma ray component of Cyg X-1 is compared with the predictions of recent models involving accretion onto a stellar black hole, and including a possible contribution from the pair annihilation 511 keV gamma ray line.

  20. A study of low-energy type II supernovae

    NASA Astrophysics Data System (ADS)

    Lisakov, Sergey M.; Dessart, Luc; Hillier, D. John; Waldman, Roni; Livne, Eli

    2015-08-01

    All stars with an initial mass greater than 8Msun, but not massive enough to encounter the pair-production instability, eventually form a degenerate core and collapse to form a compact object, either a neutron star or a black hole.At the lower mass end, these massive stars die as red-supergiant stars and give rise to Type II supernovae (SNe). The diversity of observed properties of SNe II suggests a range of progenitor mass, radii, but also explosion energy.We have performed a large grid simulations designed to cover this range of progenitor and explosion properties. Using MESA STAR, we compute a set of massive star models (12-30Msun) from the main sequence until core collapse. We then generate explosions with V1D to produce ejecta with a range of explosion energies and yields. Finally, all ejecta are evolved with CMFGEN to generate multi-band light curves and spectra.In this poster, we focus our attention on the properties of low-energy explosions that give rise to low-luminosity Type II Plateau (II-P) SNe. In particular, we present a detailed study of SN 2008bk, but also include other notorious low-energy SNe II-P like 2005cs, emphasising their non-standard properties by comparing to models that match well events like SN 1999em. Such low-energy explosions, characterised by low ejecta expansion rates, are more suitable for reliable spectral line identifications.Based on our models, we discuss the distinct signatures of low-energy explosions in lower and higher mass models. One important goal is to identify whether there is a progenitor-mass bias leading to such events.

  1. Heavy Meson Production at a Low-Energy Photon Collider

    SciTech Connect

    Asztalos, S

    2004-04-15

    A low-energy {gamma}{gamma} collider has been discussed in the context of a testbed for a {gamma}{gamma} interaction region at the Next Linear Collider(NLC). We consider the production of heavy mesons at such a testbed using Compton-backscattered photons and demonstrate that their production rivals or exceeds those by BELLE, BABAR or LEP where they are produced indirectly via virtual {gamma}{gamma} luminosities.

  2. Exchange and relaxation effects in low-energy radiationless transitions

    NASA Technical Reports Server (NTRS)

    Chen, M. H.; Crasemann, B.; Aoyagi, M.; Mark, H.

    1978-01-01

    The effect on low-energy atomic inner-shell Coster-Kronig and super Coster-Kronig transitions that is produced by relaxation and by exchange between the continuum electron and bound electrons was examined and illustrated by specific calculations for transitions that deexcite the 3p vacancy state of Zn. Taking exchange and relaxation into account is found to reduce, but not to eliminate, the discrepancies between theoretical rates and measurements.

  3. Study of low energy excitations of carbon nanotubes with DMRG

    NASA Astrophysics Data System (ADS)

    Struck, Alexander; Reyes, Sebastian A.; Eggert, Sebastian

    2010-03-01

    We examine the low-energy properties of impure carbon nanotubes including short-ranged electron-electron interactions. In particular, we calculate the local density of states (LDOS) close to selected impurities such as Stone-Wales defect and half-fullerene caps at the tube ends using the density matrix renormalization group (DMRG). We discuss the possibility to identify interaction strength and range from LDOS patterns, which reveal the interplay of electron interactions and impurities.

  4. Low-Energy Monte Carlo and W-Values

    NASA Astrophysics Data System (ADS)

    Grosswendt, B.

    Electrons in the low-energy range of about 1 keV or less play an important role in many fields of radiation research for two reasons: firstly, they are created in large numbers during the passage of all kinds of ionizing radiation through matter, and secondly, they have a linear energy transfer comparable to that of low-energy protons and a-particles, and accordingly they are responsible for the greater part of radiation damage observable in any material. A detailed understanding of the action of low-energy electrons in matter therefore is required in many contexts. In the fields of dosimetry, for example, the determination of the absorbed dose in water or the air kerma is great practical importance, but in most experiments only the amount of ionization produced by secondary electrons within the sensitive volume of a dosimeter can be measured. The results of ionization measurements therefore must converted to quantities based on energy absorption or energy transfer, either by calibration or numerically using an appropriate conversion factor. The most frequently used conversion factor is the so-called W-value, which is the mean energy required to produce an ion pair upon complete slowing down of a charged particle. Its relation to the primary particle kinetic energy T, and to the mean n umber N i of ionizations produced (ionization yield), is given by

  5. A Low energy neutrino factory for large theta(13)

    SciTech Connect

    Geer, Steve; Mena, Olga; Pascoli, Silvia; /Durham U., IPPP

    2007-01-01

    If the value of {theta}{sub 13} is within the reach of the upcoming generation of long-baseline experiments, T2K and NOvA, they show that a low-energy neutrino factory, with peak energy in the few GeV range, would provide a sensitive tool to explore CP-violation and the neutrino mass hierarchy. They consider baselines with typical length 1000-1500 km. The unique performance of the low energy neutrino factory is due to the rich neutrino oscillation pattern at energies between 1 and 4 GeV at baselines {Omicron}(1000) km. They perform both a semi-analytical study of the sensitivities and a numerical analysis to explore how well this setup can measure {theta}{sub 13}, CP-violation, and determine the type of mass hierarchy and the {theta}{sub 23} quadrant. A low energy neutrino factory provides a powerful tool to resolve ambiguities and make precise parameter determinations, for both large and fairly small values of the mixing parameter {theta}{sub 13}.

  6. Electron cooling for low-energy RHIC program

    SciTech Connect

    Fedotov, A.; Ben-Zvi, I.; Chang, X.; Kayran, D.; Litvinenko, V.N.; Pendzick, A.; Satogata, T.

    2009-08-31

    Electron cooling was proposed to increase luminosity of the RHIC collider for heavy ion beam energies below 10 GeV/nucleon. Providing collisions at such energies, termed RHIC 'low-energy' operation, will help to answer one of the key questions in the field of QCD about existence and location of critical point on the QCD phase diagram. The electron cooling system should deliver electron beam of required good quality over energies of 0.9-5 MeV. Several approaches to provide such cooling were considered. The baseline approach was chosen and design work started. Here we describe the main features of the cooling system and its expected performance. We have started design work on a low-energy RHIC electron cooler which will operate with kinetic electron energy range 0.86-2.8 (4.9) MeV. Several approaches to an electron cooling system in this energy range are being investigated. At present, our preferred scheme is to transfer the Fermilab Pelletron to BNL after Tevatron shutdown, and to use it for DC non-magnetized cooling in RHIC. Such electron cooling system can significantly increase RHIC luminosities at low-energy operation.

  7. Colorado School of Mines low energy nuclear physics project

    SciTech Connect

    Cecil, F.E.

    1991-01-02

    A major accomplishment of this project in the past year is the completion of a fairly comprehensive paper describing the survey of radiative capture reactions of protons on light nuclei at low energies. In addition we have completed a preliminary set of measurements of (d,p)/(d,{alpha}) cross section ratios on the charge symmetric nuclei {sup 6}Li and {sup 10}B as a test of the Oppenheimer-Phillips effect. While the {sup 6}Li data remain inconclusive, the {sup 10}B data show solid evidence for the Oppenheimer-Phillips enhancement of the (d,p) reaction relative to the (d,{alpha}) reaction for deuteron bombarding energies below about 100 keV. We have continued our investigation of fusion reaction products from deuterium-metal systems at room temperatures with the startling observation of intense burst of energetic charged particles from deuterium gas loaded thin titaium foils subject to non-equilibrium thermal and electrical conditions. We have completed two projects involving the application of the low energy particle accelerator to material science problems; firstly a study of the transformation of crystalline to amorphous Fe-Zr systems by proton irradiation and secondly the effects of ion bombardment on the critical temperature of YBCO high-temperature superconductors. Finally we have made progress in several instrumentation projects which will be used in some of the up-coming measurements of nuclear cross sections at very low energies.

  8. Can inflation be connected to low energy particle physics?

    SciTech Connect

    Hertzberg, Mark P.

    2012-08-01

    It is an interesting question whether low energy degrees of freedom may be responsible for early universe inflation. To examine this, here we present a simple version of Higgs-inflation with minimal coupling to gravity and a quadratic inflationary potential. This quantitatively differs from the popular non-minimally coupled models, although it is qualitatively similar. In all such models, new heavy fields must enter in order for the theory to be well behaved in the UV. We show that in all cases the Higgs self coupling λ must be quite small in order to integrate out the heavy fields and use the resulting low energy effective field theory of the Higgs to describe inflation. For moderately sized λ, the UV completion is required and will, in general, determine the inflationary regime. We discuss the important issue of the arbitrariness of the Lagrangians used in all these setups by presenting a new class of such models, including a supergravity version. This suggests that the inflationary potential is disconnected from low energy physics.

  9. Low energy description of quantum gravity and complementarity

    NASA Astrophysics Data System (ADS)

    Nomura, Yasunori; Varela, Jaime; Weinberg, Sean J.

    2014-06-01

    We consider a framework in which low energy dynamics of quantum gravity is described preserving locality, and yet taking into account the effects that are not captured by the naive global spacetime picture, e.g. those associated with black hole complementarity. Our framework employs a "special relativistic" description of gravity; specifically, gravity is treated as a force measured by the observer tied to the coordinate system associated with a freely falling local Lorentz frame. We identify, in simple cases, regions of spacetime in which low energy local descriptions are applicable as viewed from the freely falling frame; in particular, we identify a surface called the gravitational observer horizon on which the local proper acceleration measured in the observer's coordinates becomes the cutoff (string) scale. This allows for separating between the "low-energy" local physics and "trans-Planckian" intrinsically quantum gravitational (stringy) physics, and allows for developing physical pictures of the origins of various effects. We explore the structure of the Hilbert space in which the proposed scheme is realized in a simple manner, and classify its elements according to certain horizons they possess. We also discuss implications of our framework on the firewall problem. We conjecture that the complementarity picture may persist due to properties of trans-Planckian physics.

  10. On the idea of low-energy nuclear reactions in metallic lattices by producing neutrons from protons capturing "heavy" electrons

    NASA Astrophysics Data System (ADS)

    Tennfors, Einar

    2013-02-01

    The present article is a critical comment on Widom and Larsens speculations concerning low-energy nuclear reactions (LENR) based on spontaneous collective motion of protons in a room temperature metallic hydride lattice producing oscillating electric fields that renormalize the electron self-energy, adding significantly to the effective electron mass and enabling production of low-energy neutrons. The frequency and mean proton displacement estimated on the basis of neutron scattering from protons in palladium and applied to the Widom and Larsens model of the proton oscillations yield an electron mass enhancement less than one percent, far below the threshold for the proposed neutron production and even farther below the mass enhancement obtained by Widom and Larsen assuming a high charge density. Neutrons are not stopped by the Coulomb barrier, but the energy required for the neutron production is not low.

  11. Low-energy electron-induced reactions in condensed matter

    NASA Astrophysics Data System (ADS)

    Arumainayagam, Christopher R.; Lee, Hsiao-Lu; Nelson, Rachel B.; Haines, David R.; Gunawardane, Richard P.

    2010-01-01

    The goal of this review is to discuss post-irradiation analysis of low-energy (≤50 eV) electron-induced processes in nanoscale thin films. Because electron-induced surface reactions in monolayer adsorbates have been extensively reviewed, we will instead focus on low-energy electron-induced reactions in multilayer adsorbates. The latter studies, involving nanoscale thin films, serve to elucidate the pivotal role that the low-energy electron-induced reactions play in high-energy radiation-induced chemical reactions in condensed matter. Although electron-stimulated desorption (ESD) experiments conducted during irradiation have yielded vital information relevant to primary or initial electron-induced processes, we wish to demonstrate in this review that analyzing the products following low-energy electron irradiation can provide new insights into radiation chemistry. This review presents studies of electron-induced reactions in nanoscale films of molecular species such as oxygen, nitrogen trifluoride, water, alkanes, alcohols, aldehydes, ketones, carboxylic acids, nitriles, halocarbons, alkane and phenyl thiols, thiophenes, ferrocene, amino acids, nucleotides, and DNA using post-irradiation techniques such as temperature-programmed desorption (TPD), reflection-absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), gel electrophoresis, and microarray fluorescence. Post-irradiation temperature-programmed desorption, in particular, has been shown to be useful in identifying labile radiolysis products as demonstrated by the first identification of methoxymethanol as a reaction product of methanol radiolysis. Results of post-irradiation studies have been used not only to identify radiolysis products, but also to determine the dynamics of electron-induced reactions. For example, studies of the radiolysis yield as a function of incident electron energy have shown that dissociative

  12. Construction of a new type of low-energy scanning electron microscope with atomic resolution

    NASA Astrophysics Data System (ADS)

    Eastham, D. A.; Edmondson, P.; Donnelly, S.; Olsson, E.; Svensson, K.; Bleloch, A.

    2009-05-01

    energies the elastic backscattering is sensitive to the atomic species and so these can be identified directly without any energy discrimination on the detector. Furthermore it is also possible to use the microscope to do low energy electron diffraction which, because the scattering cross-section is large, can be carried out on single molecules. If these are biological samples such as DNA, proteins and viruses then the low energy means that the radiation damage is minimised. Some possibilities for mounting these samples, which can reduce radiation damage, are discussed. Finally we show a system for producing holograms of single protein molecules.

  13. Developing effective rockfall protection barriers for low energy impacts

    NASA Astrophysics Data System (ADS)

    Mentani, Alessio; Giacomini, Anna; Buzzi, Olivier; Govoni, Laura; Gottardi, Guido; Fityus, Stephen

    2016-04-01

    Recently, important progresses have been made towards the development of high capacity rockfall barriers (100 kJ - 8000 kJ). The interest of researchers and practitioners is now turning to the development of fences of minor capacity, whose use becomes essential in areas where rockfall events generally have low intensity and the use of high capacity barriers would be accompanied by excessive costs and high environmental impact. Low energy barriers can also provide a cost-effective solution even in areas where high energies events are expected. Results of full-scale tests are vital to any investigation on the behaviour of these structures. An experimental set-up has been developed at The University of Newcastle (AUS), to investigate the response of low energy rockfall barrier prototypes to low energy impacts. The Australian territory, and in particular New South Wales, is in fact characterised by rockfall events of low-to-medium intensity (50 kJ - 500 kJ) and the need of protection structures working within such energy range, is particularly felt [1]. The experiments involved the impact of a test block onto three spans, low energy barrier prototypes, made of steel structural posts, fully fixed at the base, side cables and a steel meshwork constituted by a double twist hexagonal wire net [2]. Test data enabled the development, calibration and assessment of FE models [3], on which non-linear and dynamic analyses have been performed addressing the effect of the block size. Results have shown that the response of the structure is strongly governed by the net. Data from tests conducted on the sole net and on the entire barrier showed in fact a similar trend, different to what typically observed for high capacity barriers, whose behaviour is also led by the presence of uphill cables and brakes. In particular, the numerical analyses have demonstrated a dependence of the net performance on the block size. In particular, a loss of capacity in the order of 50% occurred as the

  14. Low-energy tetrahedral polymorphs of carbon, silicon, and germanium

    NASA Astrophysics Data System (ADS)

    Mujica, Andrés; Pickard, Chris J.; Needs, Richard J.

    2015-06-01

    Searches for low-energy tetrahedral polymorphs of carbon and silicon have been performed using density functional theory computations and the ab initio random structure searching approach. Several of the hypothetical phases obtained in our searches have enthalpies that are lower or comparable to those of other polymorphs of group 14 elements that have either been experimentally synthesized or recently proposed as the structure of unknown phases obtained in experiments, and should thus be considered as particularly interesting candidates. A structure of P b a m symmetry with 24 atoms in the unit cell was found to be a low-energy, low-density metastable polymorph in carbon, silicon, and germanium. In silicon, P b a m is found to have a direct band gap at the zone center with an estimated value of 1.4 eV, which suggests applications as a photovoltaic material. We have also found a low-energy chiral framework structure of P 41212 symmetry with 20 atoms per cell containing fivefold spirals of atoms, whose projected topology is that of the so-called Cairo-type two-dimensional pentagonal tiling. We suggest that P 41212 is a likely candidate for the structure of the unknown phase XIII of silicon. We discuss P b a m and P 41212 in detail, contrasting their energetics and structures with those of other group 14 elements, particularly the recently proposed P 42/n c m structure, for which we also provide a detailed interpretation as a network of tilted diamondlike tetrahedra.

  15. Low energy electrons in the inner Earth's magnetosphere

    NASA Astrophysics Data System (ADS)

    Ganushkina, Natalia; Sillanpaa, Ilkka; Dugyagin, Stepan; Pitchford, David; Rodriguez, Juan; Runov, Andrei

    2016-04-01

    The fluxes of electrons with energies < 100 keV are not usually analyzed and modeled in details when studying the electron radiation belts. These fluxes constitute the low energy part of the seed population, which is critically important for radiation belt dynamics. Moreover, energetic electrons with energies less than about 100 keV are responsible for hazardous space-weather phenomena such as surface charging. The electron flux at these energies varies highly with geomagnetic activity and even during quiet-time periods. Significant variations in the low-energy electrons can be seen during isolated substorms, not related to any storm periods. Moreover, electron flux variations depend on the electron energy. Statistical analysis of AMC 12 CEASE II ESA instrument data (5-50 keV) and GOES MAGED data (40, 75, 150 keV) have revealed that electron fluxes increase by the same order of magnitude during isolated substorms with 200 nT of AE index and storm-time substorms with 1200 nT of AE index. If substorms are represented as electromagnetic pulses which transport and accelerate electrons additionally, how are their amplitudes determined, if not related directly to a substorm's strength? Another factor of crucial importance is the specification of boundary conditions in the electron plasma sheet. We developed a new model for electron number density and temperature in the plasma sheet as dependent on solar wind and IMF conditions based on THEMIS data analysis. We present observational and modeling results on low energy electrons in the inner magnetosphere with newly-developed, time-dependent boundary conditions with a special focus on the role of substorms for electron transport and acceleration.

  16. Low Energy Electrons in the Mars Plasma Environment

    NASA Technical Reports Server (NTRS)

    Link, Richard

    2001-01-01

    The ionosphere of Mars is rather poorly understood. The only direct measurements were performed by the Viking 1 and 2 landers in 1976, both of which carried a Retarding Potential Analyzer. The RPA was designed to measure ion properties during the descent, although electron fluxes were estimated from changes in the ion currents. Using these derived low-energy electron fluxes, Mantas and Hanson studied the photoelectron and the solar wind electron interactions with the atmosphere and ionosphere of Mars. Unanswered questions remain regarding the origin of the low-energy electron fluxes in the vicinity of the Mars plasma boundary. Crider, in an analysis of Mars Global Surveyor Magnetometer/Electron Reflectometer measurements, has attributed the formation of the magnetic pile-up boundary to electron impact ionization of exospheric neutral species by solar wind electrons. However, the role of photoelectrons escaping from the lower ionosphere was not determined. In the proposed work, we will examine the role of solar wind and ionospheric photoelectrons in producing ionization in the upper ionosphere of Mars. Low-energy (< 4 keV) electrons will be modeled using the two-stream electron transport code of Link. The code models both external (solar wind) and internal (photoelectron) sources of ionization, and accounts for Auger electron production. The code will be used to analyze Mars Global Surveyor measurements of solar wind and photoelectrons down to altitudes below 200 km in the Mars ionosphere, in order to determine the relative roles of solar wind and escaping photoelectrons in maintaining plasma densities in the region of the Mars plasma boundary.

  17. Conserved vector current test using low energy beta beams

    SciTech Connect

    Balantekin, A.B.; Jesus, J.H. de; Lazauskas, R.; Volpe, C.

    2006-04-01

    We discuss the possibility of testing the weak currents and, in particular, the weak magnetism term through the measurement of the {nu}{sub e}+p{yields}e{sup +}+n reaction at a low energy beta-beam facility. We analyze the sensitivity using both the total number of events and the angular distribution of the positrons emitted in a water Cerenkov detector. We show that the weak magnetism form factor might be determined with better than several percent accuracy using the angular distribution. This offers a new way of testing the conserved vector current hypothesis.

  18. First experimental research in low energy proton radiography

    NASA Astrophysics Data System (ADS)

    Wei, Tao; Yang, Guo-Jun; Li, Yi-Ding; Long, Ji-Dong; He, Xiao-Zhong; Zhang, Xiao-Ding; Jiang, Xiao-Guo; Ma, Chao-Fan; Zhao, Liang-Chao; Yang, Xing-Lin; Zhang, Zhuo; Wang, Yuan; Pang, Jian; Li, Hong; Li, Wei-Feng; Zhou, Fu-Xin; Shi, Jin-Shui; Zhang, Kai-Zhi; Li, Jin; Zhang, Lin-Wen; Deng, Jian-Jun

    2014-08-01

    Proton radiography is a new scatheless diagnostic tool providing a potential development direction for advanced hydrotesting. Recently a low energy proton radiography system has been developed at the Chinese Academy of Engineering Phyiscs (CAEP). This system has been designed to use an 11 MeV proton beam to radiograph thin static objects. This system consists of a proton cyclotron coupled to an imaging beamline, which is the first domestic beamline dedicated to proton radiography experiments. Via some demonstration experiments, the radiography system is confirmed to provide clear pictures with spatial resolution ~100 μm within 40 mm field-of-view.

  19. GEANT4 simulations for low energy proton computerized tomography.

    PubMed

    Milhoretto, Edney; Schelin, Hugo R; Setti, João A P; Denyak, Valery; Paschuk, Sergei A; Evseev, Ivan G; de Assis, Joaquim T; Yevseyeva, O; Lopes, Ricardo T; Vinagre Filho, Ubirajara M

    2010-01-01

    This work presents the recent results of computer simulations for the low energy proton beam tomographic scanner installed at the cyclotron CV-28 of IEN/CNEN. New computer simulations were performed in order to adjust the parameters of previous simulation within the first experimental results and to understand some specific effects that affected the form of the final proton energy spectra. To do this, the energy and angular spread of the initial proton beam were added, and the virtual phantom geometry was specified more accurately in relation to the real one. As a result, a more realistic view on the measurements was achieved.

  20. Study on electron beam in a low energy plasma focus

    SciTech Connect

    Khan, Muhammad Zubair; Ling, Yap Seong; San, Wong Chiow

    2014-03-05

    Electron beam emission was investigated in a low energy plasma focus device (2.2 kJ) using copper hollow anode. Faraday cup was used to estimate the energy of the electron beam. XR100CR X-ray spectrometer was used to explore the impact of the electron beam on the target observed from top-on and side-on position. Experiments were carried out at optimized pressure of argon gas. The impact of electron beam is exceptionally notable with two different approaches using lead target inside hollow anode in our plasma focus device.

  1. Fast self-attenuation determination of low energy gamma lines.

    PubMed

    Haddad, Kh

    2016-09-01

    Linear correlation between self-attenuation factor of 46.5keV ((210)Pb) and the 1764keV, 46.5 counts ratio has been developed in this work using triple superphosphate fertilizer samples. Similar correlation has been also developed for 63.3keV ((238)U). This correlation offers simple, fast, and accurate technique for self-attenuation determination of low energy gamma lines. Utilization of 46.5keV in the ratio has remarkably improved the technique sensitivity in comparison with other work, which used similar concept. The obtained results were used to assess the validity of transmission technique. PMID:27337648

  2. Low energy sputtering of cobalt by cesium ions

    NASA Technical Reports Server (NTRS)

    Handoo, A.; Ray, Pradosh K.

    1989-01-01

    An experimental facility to investigate low energy (less than 500 eV) sputtering of metal surfaces with ions produced by an ion gun is described. Results are reported on the sputtering yield of cobalt by cesium ions in the 100 to 500 eV energy range at a pressure of 1 times 10(exp -6) Torr. The target was electroplated on a copper substrate. The sputtered atoms were collected on a cobalt foil surrounding the target. Co-57 was used as a tracer to determine the sputtering yield.

  3. Mariner-Jupiter-Saturn Low Energy Charged Particle Experiment

    NASA Technical Reports Server (NTRS)

    Peletier, D. P.; Gary, S. A.; Hogrefe, A. F.

    1977-01-01

    The Low Energy Charged Particle Experiment will be launched on the Mariner-Jupiter-Saturn spacecraft in August 1977. The experiment has been designed to perform particle measurements in the intense radiation belts of the Jovian and Saturnian environments, and to provide detailed spectral analysis of both solar and galactic particles in interplanetary space. A single instrument uses 23 solid-state detectors configured in two distinct detector subsystems: one optimized for interplanetary and interstellar measurements, the other for specific particle species, energies, and intensities expected near the planets.

  4. Validation of GPUMCD for low-energy brachytherapy seed dosimetry

    SciTech Connect

    Hissoiny, Sami; Ozell, Benoit; Despres, Philippe; Carrier, Jean-Francois

    2011-07-15

    Purpose: To validate GPUMCD, a new package for fast Monte Carlo dose calculations based on the GPU (graphics processing unit), as a tool for low-energy single seed brachytherapy dosimetry for specific seed models. As the currently accepted method of dose calculation in low-energy brachytherapy computations relies on severe approximations, a Monte Carlo based approach would result in more accurate dose calculations, taking in to consideration the patient anatomy as well as interseed attenuation. The first step is to evaluate the capability of GPUMCD to reproduce low-energy, single source, brachytherapy calculations which could ultimately result in fast and accurate, Monte Carlo based, brachytherapy dose calculations for routine planning. Methods: A mixed geometry engine was integrated to GPUMCD capable of handling parametric as well as voxelized geometries. In order to evaluate GPUMCD for brachytherapy calculations, several dosimetry parameters were computed and compared to values found in the literature. These parameters, defined by the AAPM Task-Group No. 43, are the radial dose function, the 2D anisotropy function, and the dose rate constant. These three parameters were computed for two different brachytherapy sources: the Amersham OncoSeed 6711 and the Imagyn IsoStar IS-12501. Results: GPUMCD was shown to yield dosimetric parameters similar to those found in the literature. It reproduces radial dose functions to within 1.25% for both sources in the 0.5< r <10 cm range. The 2D anisotropy function was found to be within 3% at r = 5 cm and within 4% at r = 1 cm. The dose rate constants obtained were within the range of other values reported in the literature.Conclusion: GPUMCD was shown to be able to reproduce various TG-43 parameters for two different low-energy brachytherapy sources found in the literature. The next step is to test GPUMCD as a fast clinical Monte Carlo brachytherapy dose calculations with multiple seeds and patient geometry, potentially providing

  5. Low-energy rotational bands in the nucleus155Eu

    NASA Astrophysics Data System (ADS)

    Katajanheimo, R.; Liljavirta, H.; Siivola, A.; Hammarén, E.; Liukkonen, E.

    1984-02-01

    Excited states in the nucleus155Eu have been produced during in-beam bombardments of a154Sm target with3He beams at 22 and 27 MeV. Decay gamma rays were detected using coincidence equipment optimized for low-energy photons. The level scheme is based on the observed γγ-coincidence relationships combined with the information on relative intensities. Tentatively suggested spin assignments follow from the apparent rotational character of the nucleus. Experimental observations are compared with predictions calculated from a particle-rotor model with a nonspheroidal Woods-Saxon potential.

  6. Experimental limit on low energy antiprotons in the cosmic radiation

    NASA Technical Reports Server (NTRS)

    Streitmatter, R. E.; Stochaj, S. J.; Ormes, J. F.; Golden, R. L.; Stephens, S. A.

    1989-01-01

    Results are reported from the Low Energy Antiproton Experiment (LEAP), a balloon-borne instrument which was flown in August, 1987. No evidence of antiproton fluxes is found in the kinetic energy range of 120 MeV to 360 MeV, at the top of the atmosphere. The 90-percent is found confidence upper limit on the antiproton/proton ratio in this energy range is 3.5 x 10 to the -5th. In particular, this new experiment places an upper limit on the flux almost an order of magnitude below the reported flux of Buffington et al. (1981).

  7. RHIC RF Harmonic Numbers for Low Energy Operations

    SciTech Connect

    Satogata,T.

    2008-05-01

    There have been several test runs of RHIC operations to explore the feasibility of luminosity production at low energies. There is considerable international interest in the possible existence of a QCD phase diagram critical point in the RHIC gold-gold collision energy range of {radical}s{sub NN} = 5-50 GeV[l, 2, 3]. This paper reviews the RF harmonic number constraints for RHIC gold-gold collisions in this energy range, and concludes that optimal simultaneous collisions at both experiments are only feasible when the harmonic number is divisible by 9.

  8. Targeting Low-Energy Transfers to Low Lunar Orbit

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.; Anderson, Rodney L.

    2011-01-01

    A targeting scheme is presented to build trajectories from a specified Earth parking orbit to a specified low lunar orbit via a low-energy transfer and up to two maneuvers. The total transfer delta V (velocity) is characterized as a function of the Earth parking orbit inclination and the departure date for transfers to each given low lunar orbit. The transfer delta V (velocity) cost is characterized for transfers constructed to low lunar polar orbits with any longitude of ascending node and for transfers that arrive at the Moon at any given time during a month.

  9. HgI2 low energy beta particle detector

    NASA Technical Reports Server (NTRS)

    Shah, K. S.; Squillante, M. R.; Entine, G.

    1990-01-01

    An HgI2 device structure was designed and tested which allows HgI2 to be used to make low-energy beta-particle detectors. The devices detected tritium beta particles with an efficiency of about 25 percent. A protective encapsulant has been developed which should protect the devices for up to 20 years and will attenuate only a small fraction of the beta particles. It is noted that the devices hold significant promise to provide a practical alternative to liquid scintillation counters and gas flow-through proportional counters.

  10. Shock waves in water at low energy pulsed electric discharges

    NASA Astrophysics Data System (ADS)

    Pinchuk, M. E.; Kolikov, V. A.; Rutberg, Ph G.; Leks, A. G.; Dolinovskaya, R. V.; Snetov, V. N.; Stogov, A. Yu

    2012-12-01

    Experimental results of shock wave formation and propagation in water at low energy pulsed electric discharges are presented. To study the hydrodynamic structure of the shock waves, the direct shadow optical diagnostic device with time resolution of 5 ns and spatial resolution of 0.1 mm was designed and developed. Synchronization of the diagnostic and electrodischarge units by the fast optocouplers was carried out. The dependences of shock wave velocities after breakdown of interelectrode gap for various energy inputs (at range of <=1 J) into discharge were obtained. Based on the experimental results the recommendations for the adjustment parameters of the power supply and load were suggested.

  11. Low energy threshold corrections to neutrino masses and mixing angles

    NASA Astrophysics Data System (ADS)

    Chankowski, P. H.; Wąsowicz, P.

    2002-03-01

    We compute the low energy threshold corrections to neutrino masses and mixing in the standard model (SM) and its minimal supersymmetric version, using the effective theory technique. We demonstrate that they stabilize the results for neutrino masses and mixing with respect to the choice of the scale to which the renormalization group (RG) equation is integrated. (This confirms the correctness of the recent re-derivation of the RGE for the SM in hep-ph/0108005.) Since, as is known, those corrections are potentially very important for phenomenology we derive for them the explicit formulae that can be applied to specific models of neutrino masses and mixing.

  12. Low Energy Lorentz Violation from Modified Dispersion at High Energies.

    PubMed

    Husain, Viqar; Louko, Jorma

    2016-02-12

    Many quantum theories of gravity propose Lorentz-violating dispersion relations of the form ω=|k|f(|k|/M⋆), with recovery of approximate Lorentz invariance at energy scales much below M⋆. We show that a quantum field with this dispersion predicts drastic low energy Lorentz violation in atoms modeled as Unruh-DeWitt detectors, for any f that dips below unity somewhere. As an example, we show that polymer quantization motivated by loop quantum gravity predicts such Lorentz violation below current ion collider rapidities.

  13. Bosonization of the low energy excitations of Fermi liquids

    SciTech Connect

    Castro Neto, A.H.; Fradkin, E. )

    1994-03-07

    We bosonize the low energy excitations of Fermi liquids in any number of dimensions in the limit of long wavelengths. The bosons are a coherent superposition of electron-hole pairs and are related with the displacements of the Fermi surface in some arbitrary direction. A coherent-state path integral for the bosonized theory is derived and it is shown to represent histories of the shape of the Fermi surface. The Landau theory of Fermi liquids can be obtained from the formalism in the absence of nesting of the Fermi surface and singular interactions. We show that the Landau equation for sound waves is exact in the semiclassical approximation for the bosons.

  14. Straight low energy beam transport for intense uranium beams

    NASA Astrophysics Data System (ADS)

    Xiao, C.; Groening, L.; Vormann, H.; Mickat, S.; Hollinger, R.; Adonin, A.; Orzhekhovskaya, A.; Maier, M.; Al-Omari, H.; Barth, W.; Kester, O. K.; Yaramyshev, S.

    2015-07-01

    A new high current uranium ion source and dedicated Low Energy Beam Transport (LEBT) will be built at the GSI High Current Injector (HSI). This LEBT will be integrated into the existing complex which already comprises two branches. The paper presents the design and dynamics simulation using the TRACE-3D and TRACK code. The simulation results illustrate that this straight LEBT can transport uranium beams over a wide range of space-charge compensation, and can provide 15.4 (14.2) mA U4+ inside of the effective acceptance of the subsequent RFQ assuming the space-charge is compensated to 100% (95%).

  15. Low-Energy Hot Plasma and Particles in Saturn's Magnetosphere.

    PubMed

    Krimigis, S M; Armstrong, T P; Axford, W I; Bostrom, C O; Gloeckler, G; Keath, E P; Lanzerotti, L J; Carbary, J F; Hamilton, D C; Roelof, E C

    1982-01-29

    The low-energy charged particle instrument on Voyager 2 measured low-energy electrons and ions (energies greater, similar 22 and greater, similar 28 kiloelectron volts, respectively) in Saturn's magnetosphere. The magnetosphere structure and particle population were modified from those observed during the Voyager 1 encounter in November 1980 but in a manner consistent with the same global morphology. Major results include the following. (i) A region containing an extremely hot ( approximately 30 to 50 kiloelectron volts) plasma was identified and extends from the orbit of Tethys outward past the orbit of Rhea. (ii) The low-energy ion mantle found by Voyager 1 to extend approximately 7 Saturn radii inside the dayside magnetosphere was again observed on Voyager 2, but it was considerably hotter ( approximately 30 kiloelectron volts), and there was an indication of a cooler ( < 20 kiloelectron volts) ion mantle on the nightside. (iii) At energies greater, similar 200 kiloelectron volts per nucleon, H(1), H(2), and H(3) (molecular hydrogen), helium, carbon, and oxygen are important constituents in the Saturnian magnetosphere. The presence of both H(2) and H(3) suggests that the Saturnian ionosphere feeds plasma into the magnetosphere, but relative abundances of the energetic helium, carbon, and oxygen ions are consistent with a solar wind origin. (iv) Low-energy ( approximately 22 to approximately 60 kiloelectron volts) electron flux enhancements observed between the L shells of Rhea and Tethys by Voyager 2 on the dayside were absent during the Voyager 1 encounter. (v) Persistent asymmetric pitch-angle distributions of electrons of 60 to 200 kiloelectron volts occur in the outer magnetosphere in conjunction with the hot ion plasma torus. (vi) The spacecraft passed within approximately 1.1 degrees in longitude of the Tethys flux tube outbound and observed it to be empty of energetic ions and electrons; the microsignature of Enceladus inbound was also observed. (vii

  16. Study of energy delivery and mean free path of low energy electrons in EUV resists

    NASA Astrophysics Data System (ADS)

    Bhattarai, Suchit; Neureuther, Andrew R.; Naulleau, Patrick P.

    2016-03-01

    The relative importance of secondary electrons in delivering energy in photoresist films was assessed by performing large area exposures and by quantifying the inelastic mean free path of electrons in a leading chemically amplified positive tone EUV resist. A low energy electron microscope was used to directly pattern large (~15μm x 20μm) features with 15-80 eV electrons followed by analyzing the resulting dissolution rate contrast curve data. In the 40 to 80 eV regime the energy delivery was found to scale roughly proportionally with electron energy. In 15 to 30 eV regime however, this energy scaling did not explain the resist thickness loss data. The dose required to lower the resist thickness down to 20 nm was found to be 2-5X larger for 15 eV electrons than for 20, 25 and 30 eV electrons. Using scattering models from the literature including phonon scattering and optical data deduced electron energy loss spectroscopy and optical reflectometry, the inelastic mean free path values at energies between 10 eV and 92 eV range between about 2.8 and 0.6 nm respectively.

  17. Experimental Approach to High-Temperature Stellar Reactions with Low-Energy RI Beams

    NASA Astrophysics Data System (ADS)

    Kubono, S.; Yamaguchi, H.; Amadio, G.; Hayakawa, S.; Wakabayashi, Y.; Kurihara, Y.; He, J. J.; Saito, A.; Fujikawa, H.; Khiem, Le Hong; Niikura, M.; Teranishi, T.; Nishimura, S.; Kato, S.; Lee, C. S.; Kwon, Y. K.; Hahn, I. S.; Kim, A.

    2008-04-01

    The experimental efforts for the stellar reactions under high-temperature and high densities have been made as the major program using the RI beams from the CNS low-energy in-flight RI beam separator (CRIB) of University of Tokyo, in order to understand the evolution of the universe as well as various stellar phenomena. Specifically, two subjects of hydrogen burning are discussed here. One is a reaction study of the pp-chain and the second is of the explosive hydrogen burning, the rp-process. Some s-wave resonances have been identified by the thick target method in the crucial reaction processes in the hydrogen burning. The resonant scattering with the thick target method also succeeded in identifying inelastic resonant scattering, giving proton widths for the first excited state of the target nucleus. This provides very efficiently the reaction rate estimate for the process under high-temperature equilibrium condition. Possibilities of the CRIB facility in near future are also briefly discussed.

  18. Studying astrophysical reactions with low-energy RI beams at CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Kahl, D.; Hayakawa, S.; Sakaguchi, Y.; Wakabayashi, Y.; Hashimoto, T.; Cherubini, S.; Gulino, M.; Spitaleri, C.; Rapisarda, G. G.; La Cognata, M.; Lamia, L.; Romano, S.; Kubono, S.; Iwasa, N.; Teranishi, T.; Kawabata, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. N.; Kato, S.; Komatsubara, T.; Coc, A.; De Sereville, N.; Hammache, F.; Kiss, G.; Bishop, S.

    2016-05-01

    Studies on nuclear astrophysics, nuclear structure, and other interests have been performed using the radioactive-isotope (RI) beams at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study (CNS), the University of Tokyo. A typical measurement performed at CRIB is the elastic resonant scattering with the inverse kinematics. One recent experiment was on the α resonant scattering with 7Li and 7Be beams. This study is related to the astrophysical 7Li/7Be(α,γ) reactions, important at hot p-p chain and νp-process in supernovae. There have also been measurements based on other experimental methods. The first THM measurement using an RI beam has been performed at CRIB, to study the 18F(p, α)15O reaction at astrophysical energies via the three body reaction 2H(18F, α15O)n. The 18F(p, α) 15O reaction rate is crucial to understand the 511-keV γ-ray production in nova explosion phenomena, and we successfully evaluated the reaction cross section at novae temperature and below experimentally for the first time.

  19. Elastic electron scattering by ethyl vinyl ether

    NASA Astrophysics Data System (ADS)

    Khakoo, M. A.; Hong, L.; Kim, B.; Winstead, C.; McKoy, V.

    2010-02-01

    We report measured and calculated results for elastic scattering of low-energy electrons by ethyl vinyl ether (ethoxyethene), a prototype system for studying indirect dissociative attachment processes that may play a role in DNA damage. The integral cross section displays the expected π* shape resonance. The agreement between the calculated and measured cross sections is generally good.

  20. Recent advances in Multi-Channel Algebraic Scattering

    SciTech Connect

    Karataglidis, S.; Fraser, P. R.; Amos, K.; Canton, L.; Pisent, G.; Svenne, J. P.; Knijff, D. van der

    2011-10-28

    For coupled-channel descriptions of low-energy nucleon-induced interactions involving nuclei with particle-unstable exited states, it is necessary to include the widths of the target states. How those widths may affect the elastic scattering cross sections is examined within the framework of the Multi-Channel Algebraic Scattering (MCAS) method.

  1. Low-energy control of electrical turbulence in the heart

    NASA Astrophysics Data System (ADS)

    Luther, Stefan; Fenton, Flavio H.; Kornreich, Bruce G.; Squires, Amgad; Bittihn, Philip; Hornung, Daniel; Zabel, Markus; Flanders, James; Gladuli, Andrea; Campoy, Luis; Cherry, Elizabeth M.; Luther, Gisa; Hasenfuss, Gerd; Krinsky, Valentin I.; Pumir, Alain; Gilmour, Robert F.; Bodenschatz, Eberhard

    2011-07-01

    Controlling the complex spatio-temporal dynamics underlying life-threatening cardiac arrhythmias such as fibrillation is extremely difficult, because of the nonlinear interaction of excitation waves in a heterogeneous anatomical substrate. In the absence of a better strategy, strong, globally resetting electrical shocks remain the only reliable treatment for cardiac fibrillation. Here we establish the relationship between the response of the tissue to an electric field and the spatial distribution of heterogeneities in the scale-free coronary vascular structure. We show that in response to a pulsed electric field, E, these heterogeneities serve as nucleation sites for the generation of intramural electrical waves with a source density ρ(E) and a characteristic time, τ, for tissue depolarization that obeys the power law τ~Eα. These intramural wave sources permit targeting of electrical turbulence near the cores of the vortices of electrical activity that drive complex fibrillatory dynamics. We show in vitro that simultaneous and direct access to multiple vortex cores results in rapid synchronization of cardiac tissue and therefore, efficient termination of fibrillation. Using this control strategy, we demonstrate low-energy termination of fibrillation in vivo. Our results give new insights into the mechanisms and dynamics underlying the control of spatio-temporal chaos in heterogeneous excitable media and provide new research perspectives towards alternative, life-saving low-energy defibrillation techniques.

  2. Low energy charged particles interacting with amorphous solid water layers.

    PubMed

    Horowitz, Yonatan; Asscher, Micha

    2012-04-01

    The interaction of charged particles with condensed water films has been studied extensively in recent years due to its importance in biological systems, ecology as well as interstellar processes. We have studied low energy electrons (3-25 eV) and positive argon ions (55 eV) charging effects on amorphous solid water (ASW) and ice films, 120-1080 ML thick, deposited on ruthenium single crystal under ultrahigh vacuum conditions. Charging the ASW films by both electrons and positive argon ions has been measured using a Kelvin probe for contact potential difference (CPD) detection and found to obey plate capacitor physics. The incoming electrons kinetic energy has defined the maximum measurable CPD values by retarding further impinging electrons. L-defects (shallow traps) are suggested to be populated by the penetrating electrons and stabilize them. Low energy electron transmission measurements (currents of 0.4-1.5 μA) have shown that the maximal and stable CPD values were obtained only after a relatively slow change has been completed within the ASW structure. Once the film has been stabilized, the spontaneous discharge was measured over a period of several hours at 103 ± 2 K. Finally, UV laser photo-emission study of the charged films has suggested that the negative charges tend to reside primarily at the ASW-vacuum interface, in good agreement with the known behavior of charged water clusters.

  3. Low energy charged particles interacting with amorphous solid water layers

    NASA Astrophysics Data System (ADS)

    Horowitz, Yonatan; Asscher, Micha

    2012-04-01

    The interaction of charged particles with condensed water films has been studied extensively in recent years due to its importance in biological systems, ecology as well as interstellar processes. We have studied low energy electrons (3-25 eV) and positive argon ions (55 eV) charging effects on amorphous solid water (ASW) and ice films, 120-1080 ML thick, deposited on ruthenium single crystal under ultrahigh vacuum conditions. Charging the ASW films by both electrons and positive argon ions has been measured using a Kelvin probe for contact potential difference (CPD) detection and found to obey plate capacitor physics. The incoming electrons kinetic energy has defined the maximum measurable CPD values by retarding further impinging electrons. L-defects (shallow traps) are suggested to be populated by the penetrating electrons and stabilize them. Low energy electron transmission measurements (currents of 0.4-1.5 μA) have shown that the maximal and stable CPD values were obtained only after a relatively slow change has been completed within the ASW structure. Once the film has been stabilized, the spontaneous discharge was measured over a period of several hours at 103 ± 2 K. Finally, UV laser photo-emission study of the charged films has suggested that the negative charges tend to reside primarily at the ASW-vacuum interface, in good agreement with the known behavior of charged water clusters.

  4. New Mechanism of Low Energy Nuclear Reactions Using Superlow

    NASA Astrophysics Data System (ADS)

    Gareev, F. A.; Zhidkova, I. E.

    2006-03-01

    We proposed a new mechanism of LENR (low energy nuclear reactions) cooperative processes in the whole system - nuclei+atoms+condensed matter can occur at smaller threshold than the corresponding ones assoiciated with free constituents. The cooperative processes can be induced and enhanced by (``superlow energy'') external fields. The excess heat is the emission of internal energy, and transmutations from LENR are the result of redistribution of the internal energy of the whole system. A review of possible stimulation mechanisms of LENR is presented. We have concluded that transmutation of nuclei at low energies and excess heat are possible in the framework of the known fundamental physical laws: The universal resonance synchronization principle, and based on it, different enhancement mechanisms of reaction rates are responsible for these processes. The excitation and ionization of atoms may play the role of a trigger for LENR. F.A. Gareev, I.E. Zhidkova, E-print arXiv Nucl-th/0511092 v1 30 Nov 2005. F.A. Gareev, In: FPB-98, Novosibirsk, June 1998, p.92; F.A.Gareev, G.F. Gareeva, in: Novosibirsk, July 2000, p.161. F.A. Gareev, I.E. Zhidkova and Yu.L. Ratis, Preprint JINR P4-2004-68, Dubna, 2004. F.A. Gareev, I.E. Zhidkova, E-print arXiv Nucl-th/0505021 9 May 2005.

  5. MARLEY: Model of Argon Reaction Low Energy Yields

    NASA Astrophysics Data System (ADS)

    Gardiner, Steven; Bilton, Kyle; Grant, Christopher; Pantic, Emilija; Svoboda, Robert

    2015-10-01

    Core-collapse supernovae are sources of tremendous numbers of neutrinos with energies of up to about 50 MeV. In recent years, there has been growing interest in building detectors that are sensitive to supernova neutrinos. Such detectors can provide information about the initial stages of stellar collapse, early warning signals for light emission from supernovae, and opportunities to study neutrino oscillation physics over astronomical distances. In an effort to enable supernova neutrino detection in next-generation experiments like DUNE, the CAPTAIN collaboration plans to make the first direct measurement of cross sections for neutrino interactions on argon in the supernova energy regime. To help predict neutrino event signatures in the CAPTAIN liquid argon time projection chamber (LArTPC), we have developed a first-of-its-kind Monte Carlo event generator called MARLEY (Model of Argon Reaction Low Energy Yields). This generator attempts to model the complicated nuclear structure dependence of low-energy neutrino-nucleus reactions in sufficient detail for use in LArTPC simulations. In this talk we present some preliminary results calculated using MARLEY and discuss how the current version of the generator may be improved and expanded.

  6. Science Considerations for the NPOESS Low Energy Particle Sensor (LEPS)

    NASA Astrophysics Data System (ADS)

    Redus, R.; McGarity, J.; Mullen, E.; Dichter, B.; Evans, D.; Holeman, E.

    2005-12-01

    The Low Energy Particle Sensor (LEPS) to be developed as part of the Space Environment Sensor Suite (SESS) for the NPOESS Spacecraft is a continued enhancement of the SSJ Sensors flown on the Defense Meteorological Satellite Program (DMSP)Spacecraft since 1973. In addition to meeting the operational requirements of the DoD and civilian communities under the oversight of the USAF, NOAA and NASA, the LEPS will continue to provide the science quality data that have been used in hundreds of scientific publications and presentations. An overview of the LEPS instrument will be presented concentrating on the continued requirements for auroral oval boundary determination and auroral energy deposition and auroral particle fluxes over the energy range from 30 eV to 50 keV. Some long-term trend data and selected results of previous investigations from the USAF DMSP and NOAA POES low energy particle data will also be presented. [The science related work is sponsored in part by AFRL under contract F1962802C0086.

  7. TOPICAL REVIEW: RBE of low energy electrons and photons

    NASA Astrophysics Data System (ADS)

    Nikjoo, Hooshang; Lindborg, Lennart

    2010-05-01

    Relative biological effectiveness (RBE) compares the severity of damage induced by a radiation under test at a dose D relative to the reference radiation Dx for the same biological endpoint. RBE is an important parameter in estimation of risk from exposure to ionizing radiation (IR). The present work provides a review of the recently published data and the knowledge of the RBE of low energy electrons and photons. The review presents RBE values derived from experimental data and model calculations including cell inactivation, chromosome aberration, cell transformation, micronuclei formation and induction of double-strand breaks. Biophysical models, including physical features of radiation track, and microdosimetry parameters are presented, analysed and compared with experimental data. The biological effects of low energy electrons and photons are of particular interest in radiation biology as these are strongly absorbed in micrometer and sub-micrometer layers of tissue. RBE values not only depend on the electron and photon energies but also on the irradiation condition, cell type and experimental conditions.

  8. Einstein - Cartan - Dirac theory in the low-energy limit

    NASA Astrophysics Data System (ADS)

    Singh, P.; Ryder, L. H.

    1997-12-01

    We look for manifestations of the effects of torsion in the low-energy limit in the context of Einstein - Cartan - Dirac theory (or any theory of gravity in which the torsion tensor is purely axial). To proceed, we introduce the mathematical law governing the transport of orthonormal bases or tetrads in a spacetime with torsion. This law is applied to compute the metric and connection in a rotating and accelerating frame, or laboratory. A spin-0264-9381/14/12/031/img1 particle is placed in this rotating and accelerating frame and the low-energy limit of the Dirac equation is taken by means of the Foldy - Wouthuysen transformation. In addition to obtaining the Bonse - Wroblewski phase shift due to acceleration, Sagnac-type effects, rotation - spin couplings of the Mashhoon type, redshift of the kinetic energy and the spin - orbit coupling term of Hehl and Ni, we also obtain several interesting and significant terms as a consequence of introducing torsion into spacetime. We give a detailed interpretation of these additional terms and discuss their observability in the light of current well-known experimental techniques.

  9. Radiative neutralino production in low energy supersymmetric models

    SciTech Connect

    Basu, Rahul; Sharma, Chandradew; Pandita, P. N.

    2008-06-01

    We study the production of the lightest neutralinos in the radiative process e{sup +}e{sup -}{yields}{chi}-tilde{sub 1}{sup 0}{chi}-tilde{sub 1}{sup 0}{gamma} in low energy supersymmetric models for the International Linear Collider energies. This includes the minimal supersymmetric standard model as well as its extension with an additional chiral Higgs singlet superfield, the nonminimal supersymmetric standard model. We compare and contrast the dependence of the signal cross section on the parameters of the neutralino sector of the minimal and nonminimal supersymmetric standard model. We also consider the background to this process coming from the standard model process e{sup +}e{sup -}{yields}{nu}{nu}{gamma}, as well as from the radiative production of the scalar partners of the neutrinos (sneutrinos) e{sup +}e{sup -}{yields}{nu}-tilde{nu}-tilde*{gamma}, which can be a background to the radiative neutralino production when the sneutrinos decay invisibly. In low energy supersymmetric models radiative production of the lightest neutralinos may be the only channel to study supersymmetric partners of the standard model particles at the first stage of a linear collider, since heavier neutralinos, charginos, and sleptons may be too heavy to be pair produced at a e{sup +}e{sup -} machine with {radical}(s)=500 GeV.

  10. NOSTOS: a spherical TPC to detect low energy neutrinos

    SciTech Connect

    Aune, S.; Colas, P.; Ribas, E. Ferrer; Giomataris, Y.; Irastorza, I. G.; Dolbeau, J.; Gorodetzky, P.; Patzak, T.; Salin, P.; Fanourakis, G.; Geralis, T.; Kousouris, K.; Gounaris, G. J.; Savvidis, I.; Lepeltier, V.; Paschos, E.A.; Vergados, J.D.

    2005-09-08

    A novel low-energy ({approx}few keV) neutrino-oscillation experiment NOSTOS, combining a strong tritium source and a high pressure spherical Time Projection Chamber (TPC) detector 10 m in radius has been recently proposed. The oscillation of neutrinos of such energies occurs within the size of the detector itself, potentially allowing for a very precise (and rather systematics-free) measure of the oscillation parameters, in particular, of the smaller mixing angle {theta}13, which value could be determined for the first time. This detector could also be sensitive to the neutrino magnetic moment and be capable of accurately measure the Weinberg angle at low energy. The same apparatus, filled with high pressure Xenon, exhibits a high sensitivity as a Super Nova neutrino detector with extra galactic sensitivity. The outstanding benefits of the new concept of the spherical TPC will be presented, as well as the issues to be demonstrated in the near future by an ongoing R and D. The very first results of small prototype in operation in Saclay are shown.

  11. Low-energy QCD in the delta regime

    NASA Astrophysics Data System (ADS)

    Matzelle, Matthew E.; Tiburzi, Brian C.

    2016-02-01

    We investigate properties of low-energy QCD in a finite spatial volume, but with arbitrary temperature. In the limit of small temperature and small cube size compared to the pion Compton wavelength, Leutwyler has shown that the effective theory describing low-energy QCD reduces to that of quantum mechanics on the coset manifold, which is the so-called delta regime of chiral perturbation theory. We solve this quantum mechanics analytically for the case of a U (1 )L×U (1 )R subgroup of chiral symmetry, and numerically for the case of S U (2 )L×S U (2 )R . We utilize the quantum mechanical spectrum to compute the mass gap and chiral condensate, and investigate symmetry restoration in a finite spatial volume as a function of temperature. Because we obtain the spectrum for nonzero values of the quark mass, we are able to interpolate between the rigid rotor limit, which emerges at vanishing quark mass, and the harmonic approximation, which is referred to as the p regime. We find that the applicability of perturbation theory about the rotor limit largely requires lighter-than-physical quarks. As a stringent check of our results, we raise the temperature to that of the inverse cube size. When this condition is met, the quantum mechanics reduces to a matrix model. The condensate we obtain in this limit agrees with that determined analytically in the epsilon regime.

  12. Development of Low Energy Gap and Fully Regioregular Polythienylenevinylene Derivative

    DOE PAGES

    David, Tanya M. S.; Zhang, Cheng; Sun, Sam-Shajing

    2014-01-01

    Low energy gap and fully regioregular conjugated polymers find its wide use in solar energy conversion applications. This paper will first briefly review this type of polymers and also report synthesis and characterization of a specific example new polymer, a low energy gap, fully regioregular, terminal functionalized, and processable conjugated polymer poly-(3-dodecyloxy-2,5-thienylene vinylene) or PDDTV. The polymer exhibited an optical energy gap of 1.46 eV based on the UV-vis-NIR absorption spectrum. The electrochemically measured highest occupied molecular orbital (HOMO) level is −4.79 eV, resulting in the lowest unoccupied molecular orbital (LUMO) level of −3.33 eV based on optical energy gap. The polymer wasmore » synthesized via Horner-Emmons condensation and is fairly soluble in common organic solvents such as tetrahydrofuran and chloroform with gentle heating. DSC showed two endothermic peaks at 67°C and 227°C that can be attributed to transitions between crystalline and liquid states. The polymer is thermally stable up to about 300°C. This polymer appears very promising for cost-effective solar cell applications.« less

  13. Low Energy Laser Biostimulation: New Prospects For Medical Applications

    NASA Astrophysics Data System (ADS)

    Castel, John C.; Abergel, R. Patrick; Willner, Robert E.; Baumann, James G.

    1987-03-01

    The therapeutic benefits of light-energy is not a new concept to the modern world. Documented applications from ancient times tell of the therapeutic effects of ordinary sun-light to treat such common ailments as painful body joints, wounds, compound fractures and tetanus. The discovery of laser light in the 1960's, opened up new prospects for the medical use of light. Laser light differs from other forms of electromagnetic spectrum in that a single wavelength rather than a spectrum of wavelengths is emitted. Since the early 1970's, low-energy laser radiation has been reported to enhance wound healing rates, reduce edema, and relieve musculoskeletal pain. There is no detectable thermal effect of this laser on the tissue being treated. The effects are considered to occur as a result of photochemical, non thermal effects of the laser beam. Photons are absorbed by the tissue being treated and, in turn, produce positive therapeutic effects such as reduction of pain and edema. Pre-clinical and clinical evaluations are, presently, underway to document the safety and efficacy of low energy laser therapy, which represents a significant advance in the non-invasive treatment of pain.

  14. Very low energy supernovae and their resulting transients

    NASA Astrophysics Data System (ADS)

    Lovegrove, Elizabeth

    Core-collapse supernovae play a key role in many of astrophysical processes, but the details of how these explosive events work remain elusive. Many questions about the CCSN explosion mechanism and progenitor stars could be answered by either detecting very-low-energy supernovae (VLE SNe) or alternately placing a tight upper bound on their fraction of the CCSN population. However, VLE SNe are by definition dim events. Many VLE SNe result from the failure of the standard CCSN explosion mechanism, meaning that any observable signature must be created by secondary processes either before or during the collapse. In this dissertation I examine alternate means of producing transients in otherwise-failed CCSNe and consider the use of shock breakout flashes to both detect VLE SNe and retrieve progenitor star information. I begin by simulating neutrino-mediated mass loss in CCSNe progenitors to show that a dim, unusual, but still observable transient can be produced. I then simulate shock breakout flashes in VLE SNe for both the purposes of detection as well as extracting information about the exploding star. I discuss particular challenges of modeling shock breakout at low energies and behaviors unique to this regime, in particular the behavior of the spectral temperature. All simulations in this dissertation were done with the CASTRO radiation-hydrodynamic code.

  15. Formation of a high intensity low energy positron string

    NASA Astrophysics Data System (ADS)

    Donets, E. D.; Donets, E. E.; Syresin, E. M.; Itahashi, T.; Dubinov, A. E.

    2004-05-01

    The possibility of a high intensity low energy positron beam production is discussed. The proposed Positron String Trap (PST) is based on the principles and technology of the Electron String Ion Source (ESIS) developed in JINR during the last decade. A linear version of ESIS has been used successfully for the production of intense highly charged ion beams of various elements. Now the Tubular Electron String Ion Source (TESIS) concept is under study and this opens really new promising possibilities in physics and technology. In this report, we discuss the application of the tubular-type trap for the storage of positrons cooled to the cryogenic temperatures of 0.05 meV. It is intended that the positron flux at the energy of 1-5 eV, produced by the external source, is injected into the Tubular Positron Trap which has a similar construction as the TESIS. Then the low energy positrons are captured in the PST Penning trap and are cooled down because of their synchrotron radiation in the strong (5-10 T) applied magnetic field. It is expected that the proposed PST should permit storing and cooling to cryogenic temperature of up to 5×109 positrons. The accumulated cooled positrons can be used further for various physics applications, for example, antihydrogen production.

  16. Low energy charged particles interacting with amorphous solid water layers

    SciTech Connect

    Horowitz, Yonatan; Asscher, Micha

    2012-04-07

    The interaction of charged particles with condensed water films has been studied extensively in recent years due to its importance in biological systems, ecology as well as interstellar processes. We have studied low energy electrons (3-25 eV) and positive argon ions (55 eV) charging effects on amorphous solid water (ASW) and ice films, 120-1080 ML thick, deposited on ruthenium single crystal under ultrahigh vacuum conditions. Charging the ASW films by both electrons and positive argon ions has been measured using a Kelvin probe for contact potential difference (CPD) detection and found to obey plate capacitor physics. The incoming electrons kinetic energy has defined the maximum measurable CPD values by retarding further impinging electrons. L-defects (shallow traps) are suggested to be populated by the penetrating electrons and stabilize them. Low energy electron transmission measurements (currents of 0.4-1.5 {mu}A) have shown that the maximal and stable CPD values were obtained only after a relatively slow change has been completed within the ASW structure. Once the film has been stabilized, the spontaneous discharge was measured over a period of several hours at 103 {+-} 2 K. Finally, UV laser photo-emission study of the charged films has suggested that the negative charges tend to reside primarily at the ASW-vacuum interface, in good agreement with the known behavior of charged water clusters.

  17. High field - low energy muon ionization cooling channel

    NASA Astrophysics Data System (ADS)

    Kamal Sayed, Hisham; Palmer, Robert B.; Neuffer, David

    2015-09-01

    Muon beams are generated with large transverse and longitudinal emittances. In order to achieve the low emittances required by a muon collider, within the short lifetime of the muons, ionization cooling is required. Cooling schemes have been developed to reduce the muon beam 6D emittances to ≈300 μ m -rad in transverse and ≈1 - 1.5 mm in longitudinal dimensions. The transverse emittance has to be further reduced to ≈50 - 25 μ m -rad with an upper limit on the longitudinal emittance of ≈76 mm in order to meet the high-energy muon collider luminosity requirements. Earlier studies of the transverse cooling of low energy muon beams in high field magnets showed a promising performance, but did not include transverse or longitudinal matching between the stages. In this study we present the first complete design of the high field-low energy ionization cooling channel with transverse and longitudinal matching. The channel design was based on strong focusing solenoids with fields of 25-30 T and low momentum muon beam starting at 135 MeV /c and gradually decreasing. The cooling channel design presented here is the first to reach ≈50 micron scale emittance beam. We present the channel's optimized design parameters including the focusing solenoid fields, absorber parameters and the transverse and longitudinal matching.

  18. Deep absorbing porphyrin small molecule for high-performance organic solar cells with very low energy losses.

    PubMed

    Gao, Ke; Li, Lisheng; Lai, Tianqi; Xiao, Liangang; Huang, Yuan; Huang, Fei; Peng, Junbiao; Cao, Yong; Liu, Feng; Russell, Thomas P; Janssen, René A J; Peng, Xiaobin

    2015-06-17

    We designed and synthesized the DPPEZnP-TEH molecule, with a porphyrin ring linked to two diketopyrrolopyrrole units by ethynylene bridges. The resulting material exhibits a very low energy band gap of 1.37 eV and a broad light absorption to 907 nm. An open-circuit voltage of 0.78 V was obtained in bulk heterojunction (BHJ) organic solar cells, showing a low energy loss of only 0.59 eV, which is the first report that small molecule solar cells show energy losses <0.6 eV. The optimized solar cells show remarkable external quantum efficiency, short circuit current, and power conversion efficiency up to 65%, 16.76 mA/cm(2), and 8.08%, respectively, which are the best values for BHJ solar cells with very low energy losses. Additionally, the morphology of DPPEZnP-TEH neat and blend films with PC61BM was studied thoroughly by grazing incidence X-ray diffraction, resonant soft X-ray scattering, and transmission electron microscopy under different fabrication conditions.

  19. Four-nucleon potential due to exchange of pions

    SciTech Connect

    Robilotta, M.R.

    1985-03-01

    A four-body force due to the exchange of pions has been derived by means of It includes effects corresponding to pion-pion scattering, pion production, and pion-nucleon rescattering. The strength parameters of this four-body potential are typically one order of magnitude smaller than those of the two-pion-exchange three-body force.

  20. Tissue modeling schemes in low energy breast brachytherapy.

    PubMed

    Afsharpour, Hossein; Landry, Guillaume; Reniers, Brigitte; Pignol, Jean-Philippe; Beaulieu, Luc; Verhaegen, Frank

    2011-11-21

    Breast tissue is heterogeneous and is mainly composed of glandular (G) and adipose (A) tissues. The proportion of G versus A varies considerably among the population. The absorbed dose distributions in accelerated partial breast irradiation therapy with low energy photon brachytherapy sources are very sensitive to tissue heterogeneities. Current clinical algorithms use the recommendations of the AAPM TG43 report which approximates the human tissues by unit density water. The aim of this study is to investigate various breast tissue modeling schemes for low energy brachytherapy. A special case of breast permanent seed implant is considered here. Six modeling schemes are considered. Uniform and non-uniform water breast (UWB and NUWB) consider the density but neglect the effect of the composition of tissues. The uniform and the non-uniform G/A breast (UGAB and NUGAB) as well the age-dependent breast (ADB) models consider the effect of the composition. The segmented breast tissue (SBT) method uses a density threshold to distinguish between G and A tissues. The PTV D(90) metric is used for the analysis and is based on the dose to water (D(90(w,m))). D(90(m,m)) is also reported for comparison to D(90(w,m)). The two-month post-implant D(90(w,m)) averaged over 38 patients is smaller in NUWB than in UWB by about 4.6% on average (ranging from 5% to 13%). Large average differences of G/A breast models with TG43 (17% and 26% in UGAB and NUGAB, respectively) show that the effect of the chemical composition dominates the effect of the density on dose distributions. D(90(w,m)) is 12% larger in SBT than in TG43 when averaged. These differences can be as low as 4% or as high as 20% when the individual patients are considered. The high sensitivity of dosimetry on the modeling scheme argues in favor of an agreement on a standard tissue modeling approach to be used in low energy breast brachytherapy. SBT appears to generate the most geometrically reliable breast tissue models in this

  1. Variations of Low-energy Ion Distributions Measured in the Heliosheath

    SciTech Connect

    Decker, R. B.; Roelof, E. C.; Hill, M. E.; Krimigis, S. M.

    2010-12-30

    This report is an update of low-energy ion intensities and angular distributions measured recently by the Low Energy Charged Particle instruments on the Voyager 1 and 2 spacecraft in the inner heliosheath.

  2. Summary of low-energy aspects of QCD and medium-energy hadron parallel sessions

    SciTech Connect

    McClelland, J.B.

    1991-01-01

    Two sessions were organized dealing with low energy aspects of QCD. The first dealt with the issue of QCD dibaryons. The second session centered on mostly low-energy tests of QCD. This report discusses experiments dealing with these sessions.

  3. Low-energy inelastic collisions of OH radicals with He atoms and D{sub 2} molecules

    SciTech Connect

    Kirste, Moritz; Scharfenberg, Ludwig; Meijer, Gerard; Meerakker, Sebastiaan Y. T. van de; Klos, Jacek; Lique, Francois; Alexander, Millard H.

    2010-10-15

    We present an experimental study on the rotational inelastic scattering of OH (X {sup 2}{Pi}{sub 3/2},J=3/2,f) radicals with He and D{sub 2} at collision energies between 100 and 500 cm{sup -1} in a crossed beam experiment. The OH radicals are state selected and velocity tuned using a Stark decelerator. Relative parity-resolved state-to-state inelastic scattering cross sections are accurately determined. These experiments complement recent low-energy collision studies between trapped OH radicals and beams of He and D{sub 2} that are sensitive to the total (elastic and inelastic) cross sections [Sawyer et al., Phys. Rev. Lett. 101, 203203 (2008)], but for which the measured cross sections could not be reproduced by theoretical calculations [Pavlovic et al., J. Phys. Chem. A 113, 14670 (2009)]. For the OH-He system, our experiments validate the inelastic cross sections determined from rigorous quantum calculations.

  4. Ionization efficiency study for low energy nuclear recoils in germanium

    NASA Astrophysics Data System (ADS)

    Barker, D.; Wei, W.-Z.; Mei, D.-M.; Zhang, C.

    2013-08-01

    We used the internal conversion (E0 transition) of germanium-72 to indirectly measure the low energy nuclear recoils of germanium. Together with a reliable Monte Carlo package, in which we implement the internal conversion process, the data was compared to the Lindhard (k = 0.159) and Barker-Mei models. A shape analysis indicates that both models agree well with data in the region of interest within 4%. The most probable value (MPV) of the nuclear recoils obtained from the shape analysis is 17.5 ± 0.12 (sys) ±0.035 (stat) keV with an average path-length of 0.014 μm.

  5. Xantusiid lizards have low energy, water, and food requirements.

    PubMed

    Mautz, W J; Nagy, K A

    2000-01-01

    Lizards in the family Xantusiidae (the night lizards) are known to have resting metabolic rates that are only half those of other lizards of comparable size. We evaluated whether xantusiids also have low field metabolic rates (FMR) and food requirements by measuring FMR and water flux rates with doubly labeled water in three xantusiid species in their natural habitats. Free-living Xantusia vigilis, Xantusia henshawi, and Xantusia riversiana processed energy and water very slowly, about one-third as fast as do other reptiles of similar size. Xantusiid lizards have a distinctive life history that is characterized by very slow growth and low reproductive rates, and they are intensely reclusive. This general lifestyle is also found in some species that live in environments with scarce food resources, such as in caves and in arid habitats, and these species may also have relatively low energy requirements.

  6. [Low-energy laser therapy in medial tibial stress syndrome].

    PubMed

    Nissen, L R; Astvad, K; Madsen, L

    1994-12-01

    The effect of low-energy laser therapy on shin splints was examined in a randomized study with an unblinded design. Constripts from the Jutland Dragoon regiment with shin splints were given either active laser treatment (40 mW in 60 sec per cm tender tibia edge) or placebo laser. All patients were exempted from normal duty concerning activities like running and march. Forty-nine patients participated in the study, 23 in the laser group and 26 in the control group. From the start the study was designed to be double-blind, but by accident the code was broken towards the end of the study. We found no significant differences between the groups regarding pain visual analog score and readiness to return to active duty after 14 days.

  7. Contamination control and plume assessment of low-energy thrusters

    NASA Technical Reports Server (NTRS)

    Scialdone, John J.

    1993-01-01

    Potential contamination of a spacecraft cryogenic surface by a xenon (Xe) ion generator was evaluated. The analysis involves the description of the plume exhausted from the generator with its relative component fluxes on the spacecraft surfaces, and verification of the conditions for condensation, adsorption, and sputtering at those locations. The data describing the plume fluxes and their effects on surfaces were obtained from two sources: the tests carried out with the Xe generator in a small vacuum chamber to indicate deposits and sputter on monitor slides; and the extensive tests with a mercury (Hg) ion thruster in a large vacuum chamber. The Hg thruster tests provided data on the neutrals, on low-energy ion fluxes, on high-energy ion fluxes, and on sputtered materials at several locations within the plume.

  8. Low-Energy Ions from Laser-Cooled Atoms

    NASA Astrophysics Data System (ADS)

    Shayeganrad, G.; Fioretti, A.; Guerri, I.; Tantussi, F.; Ciampini, D.; Allegrini, M.; Viteau, M.; Fuso, F.

    2016-05-01

    We report the features of an ion source based on two-color photoionization of a laser-cooled cesium beam outsourced from a pyramidal magneto-optical trap. The ion source operates in continuous or pulsed mode. At acceleration voltages below 300 V, it delivers some ten ions per bunch with a relative energy spread Δ Urms/U ≃0.032 , as measured through the retarding field-energy-analyzer approach. Space-charge effects are negligible thanks to the low ion density attained in the interaction volume. The performances of the ion beam in a configuration using focused laser beams are extrapolated on the basis of the experimental results. Calculations demonstrate that our low-energy and low-current ion beam can be attractive for the development of emerging technologies requiring the delivery of a small amount of charge, down to the single-ion level and its eventual focusing in the 10-nm range.

  9. Ignitor with stable low-energy thermite igniting system

    DOEpatents

    Kelly, Michael D.; Munger, Alan C.

    1991-02-05

    A stable compact low-energy igniting system in an ignitor utilizes two components, an initiating charge and an output charge. The initiating charge is a thermite in ultra-fine powder form compacted to 50-70% of theoretical maximum density and disposed in a cavity of a header of the ignitor adjacent to an electrical ignition device, or bridgewire, mounted in the header cavity. The initiating charge is ignitable by operation of the ignition device in a hot-wire mode. The output charge is a thermite in high-density consoladated form compacted to 90-99% of theoretical maximum density and disposed adjacent to the initiating charge on an opposite end thereof from the electrical ignition device and ignitable by the initiating charge. A sleeve is provided for mounting the output charge to the ignitor header with the initiating charge confined therebetween in the cavity.

  10. ULTRA-LOW-ENERGY HIGH-CURRENT ION SOURCE

    SciTech Connect

    Anders, Andre; Yushkov, Georgy Yu.; Baldwin, David A.

    2009-11-20

    The technical objective of the project was to develop an ultra-low-energy, high-intensity ion source (ULEHIIS) for materials processing in high-technology fields including semiconductors, micro-magnetics and optics/opto-electronics. In its primary application, this ion source can be incorporated into the 4Wave thin-film deposition technique called biased target ion-beam deposition (BTIBD), which is a deposition technique based on sputtering (without magnetic field, i.e., not the typical magnetron sputtering). It is a technological challenge because the laws of space charge limited current (Child-Langmuir) set strict limits of how much current can be extracted from a reservoir of ions, such as a suitable discharge plasma. The solution to the problem was an innovative dual-discharge system without the use of extraction grids.

  11. Status report on the Low Energy Neutron Source for 2015

    NASA Astrophysics Data System (ADS)

    Baxter, D. V.; Rinckel, T.

    2016-11-01

    The Low Energy Neutron Source at Indiana University first produced cold neutrons in April of 2005. Ten years after first reaching this milestone, the facility has three instruments in operation on its cold target station, and a second target station is devoted to thermal and fast neutron physics offers capabilities in radiation effects research (single-event effects in electronics) and radiography. Key elements in our success over these last ten years have been the diversity of activities we have been able maintain (which often involves using each of our instruments for multiple different activities), the close relationship we have developed with a number of major sources, and the focus we have had on innovation in neutron instrumentation. In this presentation, we will introduce some of the highlights from our most recent activities, provide an update on some of our technical challenges, and describe some of our ideas for the future.

  12. Molecular ion sources for low energy semiconductor ion implantation (invited)

    NASA Astrophysics Data System (ADS)

    Hershcovitch, A.; Gushenets, V. I.; Seleznev, D. N.; Bugaev, A. S.; Dugin, S.; Oks, E. M.; Kulevoy, T. V.; Alexeyenko, O.; Kozlov, A.; Kropachev, G. N.; Kuibeda, R. P.; Minaev, S.; Vizir, A.; Yushkov, G. Yu.

    2016-02-01

    Smaller semiconductors require shallow, low energy ion implantation, resulting space charge effects, which reduced beam currents and production rates. To increase production rates, molecular ions are used. Boron and phosphorous (or arsenic) implantation is needed for P-type and N-type semiconductors, respectively. Carborane, which is the most stable molecular boron ion leaves unacceptable carbon residue on extraction grids. A self-cleaning carborane acid compound (C4H12B10O4) was synthesized and utilized in the ITEP Bernas ion source resulting in large carborane ion output, without carbon residue. Pure gaseous processes are desired to enable rapid switch among ion species. Molecular phosphorous was generated by introducing phosphine in dissociators via 4PH3 = P4 + 6H2; generated molecular phosphorous in a pure gaseous process was then injected into the HCEI Calutron-Bernas ion source, from which P4+ ion beams were extracted. Results from devices and some additional concepts are described.

  13. Effects of heavy sea quarks at low energies.

    PubMed

    Bruno, Mattia; Finkenrath, Jacob; Knechtli, Francesco; Leder, Björn; Sommer, Rainer

    2015-03-13

    We present a factorization formula for the dependence of light hadron masses and low energy hadronic scales on the mass M of a heavy quark: apart from an overall mass-independent factor Q, ratios such as r_{0}(M)/r_{0}(0) are computable in perturbation theory at large M. The perturbation theory part is stable concerning different loop orders. Our nonperturbative Monte Carlo results obtained in a model calculation, where a doublet of heavy quarks is decoupled, match quantitatively to the perturbative prediction. Upon taking ratios of different hadronic scales at the same mass, the perturbative function drops out and the ratios are given by the decoupled theory up to M^{-2} corrections. We verify-in the continuum limit-that the sea quark effects of quarks with masses around the charm mass are very small in such ratios.

  14. Analysis of a QCD Hamiltonian in the low energy regime.

    NASA Astrophysics Data System (ADS)

    Yépez-Martínez, T.; Amor Quiroz, D. A.; Hess, P. O.; Civitarese, O.

    2016-07-01

    We present a QCD motivated Hamiltonian for the light quark sector. Inspired from self-consistent analysis of the Coulomb interaction, we implement an interaction of the form (-a/r + br) between color sources, which already consider gluonic dynamics by the linear potential contribution. A prediagonalization of the kinetic energy term followed by the implementation of the Tamm-Dancoff method are used to obtain the eigenvalues of the Hamiltonian. A variational analysis is implemented to obtain the optimized basis for the low energy meson spectrum. The potential parameter is compared to the reported lattice string tension with relatively good agreement. The obtained energies are located close to the experimental values and further improvements are discussed.

  15. HIGH INTENSITY LOW-ENERGY POSITRON SOURCE AT JEFFERSON

    SciTech Connect

    Serkan Golge, Bogdan Wojtsekhowski, Branislav Vlahovic

    2012-07-01

    We present a novel concept of a low-energy e{sup +} source with projected intensity on the order of 10{sup 10} slow e{sup +}/s. The key components of this concept are a continuous wave e{sup -} beam, a rotating positron-production target, a synchronized raster/anti-raster, a transport channel, and extraction of e{sup +} into a field-free area through a magnetic plug for moderation in a cryogenic solid. Components were designed in the framework of GEANT4-based (G4beamline) Monte Carlo simulation and TOSCA magnetic field calculation codes. Experimental data to demonstrate the effectiveness of the magnetic plug is presented.

  16. Molecular ion sources for low energy semiconductor ion implantation (invited).

    PubMed

    Hershcovitch, A; Gushenets, V I; Seleznev, D N; Bugaev, A S; Dugin, S; Oks, E M; Kulevoy, T V; Alexeyenko, O; Kozlov, A; Kropachev, G N; Kuibeda, R P; Minaev, S; Vizir, A; Yushkov, G Yu

    2016-02-01

    Smaller semiconductors require shallow, low energy ion implantation, resulting space charge effects, which reduced beam currents and production rates. To increase production rates, molecular ions are used. Boron and phosphorous (or arsenic) implantation is needed for P-type and N-type semiconductors, respectively. Carborane, which is the most stable molecular boron ion leaves unacceptable carbon residue on extraction grids. A self-cleaning carborane acid compound (C4H12B10O4) was synthesized and utilized in the ITEP Bernas ion source resulting in large carborane ion output, without carbon residue. Pure gaseous processes are desired to enable rapid switch among ion species. Molecular phosphorous was generated by introducing phosphine in dissociators via 4PH3 = P4 + 6H2; generated molecular phosphorous in a pure gaseous process was then injected into the HCEI Calutron-Bernas ion source, from which P4(+) ion beams were extracted. Results from devices and some additional concepts are described.

  17. The low energy spectra of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Bussard, R. W.; Lamb, F. K.

    1982-01-01

    The implications of observed gamma-ray burst spectra for the physical conditions and geometries of the sources are examined. It is noted that an explanation of the continua in terms of optically thin thermal bremsstrahlung requires a relatively large area but a fairly shallow depth. On the other hand, a spectrum similar to that observed could be produced by rapid flickering of sources with less extreme geometries if each flicker emits a Comptonized thermal spectrum. Either field inhomogeneities or plasma motions are required to interpret the low energy features as cyclotron extinction. An alternative explanation is photoelectric absorption by heavy atoms; this requires a field strength high enough to make one-photon electron positron annihilation possible. Observational tests of these possibilities are proposed

  18. A New Instrument Design for Imaging Low Energy Neutral Atoms

    NASA Technical Reports Server (NTRS)

    Keller, John W.; Collier, Michael R.; Chornay, Dennis; Rozmarynowski, Paul; Getty, Stephanie; Cooper, John F.; Smith, Billy

    2007-01-01

    The MidSTAR-2 satellite, to be built at the US Naval Academy as a follow-on to the successful MidSTAR-1 satellite (http://web.ew.usna.edu/midstar/), will launch in 2011 and carry three Goddard Space Flight Center (GSFC) experiments developed under Goddard's Internal Research and Development (IRAD) program. One of these GSFC instruments, the Miniature Imager for Neutral Ionospheric atoms and Magnetospheric Electrons (MINI-ME) builds on the heritage of the Goddard-developed Low-Energy Neutral Atom (LENA) imager launched on the IMAGE spacecraft in 2000. MINI-ME features a Venetian-blind conversion surface assembly that improves both light rejection and conversion efficiency in a smaller and lighter package than LENA making this an highly effective instrument for viewing solar wind charge exchange with terrestrial and planetary exospheres. We will describe the MINI-ME prototyping effort and its science targets.

  19. Modeling of human movement monitoring using Bluetooth Low Energy technology.

    PubMed

    Mokhtari, G; Zhang, Q; Karunanithi, M

    2015-01-01

    Bluetooth Low Energy (BLE) is a wireless communication technology which can be used to monitor human movements. In this monitoring system, a BLE signal scanner scans signal strength of BLE tags carried by people, to thus infer human movement patterns within its monitoring zone. However to the extent of our knowledge one main aspect of this monitoring system which has not yet been thoroughly investigated in literature is how to build a sound theoretical model, based on tunable BLE communication parameters such as scanning time interval and advertising time interval, to enable the study and design of effective and efficient movement monitoring systems. In this paper, we proposed and developed a statistical model based on Monte-Carlo simulation, which can be utilized to assess impacts of BLE technology parameters in terms of latency and efficiency, on a movement monitoring system, and can thus benefit a more efficient system design.

  20. Bluetooth low energy: wireless connectivity for medical monitoring.

    PubMed

    Omre, Alf Helge

    2010-03-01

    Electronic wireless sensors could cut medical costs by enabling physicians to remotely monitor vital signs such as blood pressure, blood glucose, and blood oxygenation while patients remain at home. According to the IDC report "Worldwide Bluetooth Semiconductor 2008-2012 Forecast," published November 2008, a forthcoming radio frequency communication ("wireless connectivity") standard, Bluetooth low energy, will link wireless sensors via radio signals to the 70% of cell phones and computers likely to be fitted with the next generation of Bluetooth wireless technology, leveraging a ready-built infrastructure for data transmission. Analysis of trends indicated by this data can help physicians better manage diseases such as diabetes. The technology also addresses the concerns of cost, compatibility, and interoperability that have previously stalled widespread adoption of wireless technology in medical applications.

  1. Advanced satellite sensors: Low Energy Neutral Atom (LENA) imager

    SciTech Connect

    Funsten, H.O.; McComas, D.J.

    1996-09-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Imaging of low energy neutral atoms (LENDs) created by electron capture by magnetospheric plasma ions from interactions with cold geocoronal neutrals promises to be a revolutionary technique for providing unprecedented information about the global structure and dynamics of the terrestrial magnetosphere. This has significant implications in space weather forecasting, weather-induced satellite upset diagnostics, and revolutionary insights into global magnetospheric physics. The Los Alamos Space and Atmospheric Sciences Group has completed extensive neutral atom simulations and detailed instrument definition, and we designed a proof-of-concept demonstration prototype and have obtained externally- funded programs for full instrument development

  2. Linac4 low energy beam measurements with negative hydrogen ions

    NASA Astrophysics Data System (ADS)

    Scrivens, R.; Bellodi, G.; Crettiez, O.; Dimov, V.; Gerard, D.; Granemann Souza, E.; Guida, R.; Hansen, J.; Lallement, J.-B.; Lettry, J.; Lombardi, A.; Midttun, Ø.; Pasquino, C.; Raich, U.; Riffaud, B.; Roncarolo, F.; Valerio-Lizarraga, C. A.; Wallner, J.; Yarmohammadi Satri, M.; Zickler, T.

    2014-02-01

    Linac4, a 160 MeV normal-conducting H- linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H- beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.

  3. Low energy electron magnetometer using a monoenergetic electron beam

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Wood, G. M.; Rayborn, G. H.; White, F. A. (Inventor)

    1983-01-01

    A low energy electron beam magnetometer utilizes near-monoenergetic electrons thereby reducing errors due to electron energy spread and electron nonuniform angular distribution. In a first embodiment, atoms in an atomic beam of an inert gas are excited to a Rydberg state and then electrons of near zero energy are detached from the Rydberg atoms. The near zero energy electrons are then accelerated by an electric field V(acc) to form the electron beam. In a second embodiment, a filament emits electrons into an electrostatic analyzer which selects electrons at a predetermined energy level within a very narrow range. These selected electrons make up the electron beam that is subjected to the magnetic field being measured.

  4. Low-energy ion implantation: Large mass fractionation of argon

    NASA Technical Reports Server (NTRS)

    Ponganis, K. V.; Graf, TH.; Marti, K.

    1993-01-01

    The isotropic signatures of noble gases in the atmospheres of the Earth and other planets are considerably evolved when compared to signatures observed in the solar wind. The mechanisms driving the evolution of planetary volatiles from original compositions in the solar accretion disk are currently poorly understood. Modeling of noble-gas compositional histories requires knowledge of fractionating processes that may have operated through the evolutionary stages. Since these gases are chemically inert, information on noble-gas fractionation processes can be used as probes. The importance of understanding these processes extends well beyond 'noble-gas planetology.' Trapped argon acquired by low-energy implantation (approximately less than 100 eV) into solids is strongly mass fractionated (approximately greater than or equal to 3 percent/amu). This has potential implications for the origin and evolution of terrestrial planet atmospheres.

  5. The nuclear structure and low-energy reactions (NSLER) collaboration

    NASA Astrophysics Data System (ADS)

    Dean, D. J.; NSLER Collaboration

    2006-09-01

    The long-term vision of the Nuclear Structure and Low-Energy Reactions (NSLER) collaboration is to arrive at a comprehensive and unified description of nuclei and their reactions that is grounded in the interactions between the constituent nucleons. For this purpose, we will develop a universal energy density functional for nuclei and replace current phenomenological models of nuclear structure and reactions with a well-founded microscopic theory that will deliver maximum predictive power with minimal uncertainties that are well quantified. Nuclear structure and reactions play an essential role in the science to be investigated at rare isotope facilities, and in nuclear physics applications to the Science-Based Stockpile Stewardship Program, next-generation reactors, and threat reduction. We anticipate an expansion of the computational techniques and methods we currently employ, and developments of new treatments, to take advantage of petascale architectures and demonstrate the capability of the leadership class machines to deliver new science heretofore impossible.

  6. Low-energy antinucleon-nucleus interaction revisited

    NASA Astrophysics Data System (ADS)

    Friedman, E.

    2015-08-01

    Annihilation cross sections of antiprotons and antineutrons on the proton between 50 and 400 MeV/c show Coulomb focusing below 200 MeV/c and almost no charge-dependence above 200 MeV/c. Similar comparisons for heavier targets are not possible for lack of overlap between nuclear targets studied with and beams. Interpolating between -nucleus annihilation cross sections with the help of an optical potential to compare with -nucleus annihilation cross sections reveal unexpected features of Coulomb interactions in the latter. Direct comparisons between -nucleus and -nucleus annihilations at very low energies could be possible if cross sections are measured on the same targets and at the same energies as the available cross sections for . Such measurements may be feasible in the foreseeable future.

  7. Oxidation of nickel surfaces by low energy ion bombardment

    NASA Astrophysics Data System (ADS)

    Saric, Iva; Peter, Robert; Kavre, Ivna; Badovinac, Ivana Jelovica; Petravic, Mladen

    2016-03-01

    We have studied formation of oxides on Ni surfaces by low energy oxygen bombardment using X-ray photoemission spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Different oxidation states of Ni ions have been identified in XPS spectra measured around Ni 2p and O 1s core-levels. We have compared our results with thermal oxidation of Ni and shown that ion bombardment is more efficient in creating thin oxide films on Ni surfaces. The dominant Ni-oxide in both oxidation processes is NiO (Ni2+ oxidation state), while some Ni2O3 contributions (Ni3+ oxidation state) are still present in all oxidised samples. The oxide thickness of bombarded Ni samples, as determined by SIMS, was shown to be related to the penetration depth of oxygen ions in Ni.

  8. Modeling of human movement monitoring using Bluetooth Low Energy technology.

    PubMed

    Mokhtari, G; Zhang, Q; Karunanithi, M

    2015-01-01

    Bluetooth Low Energy (BLE) is a wireless communication technology which can be used to monitor human movements. In this monitoring system, a BLE signal scanner scans signal strength of BLE tags carried by people, to thus infer human movement patterns within its monitoring zone. However to the extent of our knowledge one main aspect of this monitoring system which has not yet been thoroughly investigated in literature is how to build a sound theoretical model, based on tunable BLE communication parameters such as scanning time interval and advertising time interval, to enable the study and design of effective and efficient movement monitoring systems. In this paper, we proposed and developed a statistical model based on Monte-Carlo simulation, which can be utilized to assess impacts of BLE technology parameters in terms of latency and efficiency, on a movement monitoring system, and can thus benefit a more efficient system design. PMID:26737430

  9. Space charge effects in the SSC Low Energy Booster

    SciTech Connect

    Machida, S.; Bourianoff, G.; Mahale, N.K.; Mehta, N.; Pilat, F.; Talman, R.; York, R.C.

    1991-05-01

    By means of multi-particle tracking, we explore space charge effects in the Low Energy Booster (LEB) which has a strong requirement for small transverse emittance. Macro-particles are tracked in a self-consistent manner in six dimensional phase space with transverse space charge kicks so that the emittance evolution as well as the particle distribution are simulated as a function of time. Among recent improvements of the code, the longitudinal motion, i.e. synchrotron oscillations as well as acceleration, makes it possible to simulate the capture process of linac microbunches. The code was calibrated by comparing with the experimental results at the Fermilab Booster. Preliminary results of the LEB show slow emittance growth due to the space charge. 5 refs., 5 figs., 1 tab.

  10. Linac4 low energy beam measurements with negative hydrogen ions

    SciTech Connect

    Scrivens, R. Bellodi, G.; Crettiez, O.; Dimov, V.; Gerard, D.; Granemann Souza, E.; Guida, R.; Hansen, J.; Lallement, J.-B.; Lettry, J.; Lombardi, A.; Midttun, Ø.; Pasquino, C.; Raich, U.; Riffaud, B.; Roncarolo, F.; Valerio-Lizarraga, C. A.; Wallner, J.; Yarmohammadi Satri, M.; Zickler, T.

    2014-02-15

    Linac4, a 160 MeV normal-conducting H{sup −} linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H{sup −} beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.

  11. Linac4 low energy beam measurements with negative hydrogen ions.

    PubMed

    Scrivens, R; Bellodi, G; Crettiez, O; Dimov, V; Gerard, D; Granemann Souza, E; Guida, R; Hansen, J; Lallement, J-B; Lettry, J; Lombardi, A; Midttun, Ø; Pasquino, C; Raich, U; Riffaud, B; Roncarolo, F; Valerio-Lizarraga, C A; Wallner, J; Yarmohammadi Satri, M; Zickler, T

    2014-02-01

    Linac4, a 160 MeV normal-conducting H(-) linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H(-) beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.

  12. Hierarchical fuzzy control of low-energy building systems

    SciTech Connect

    Yu, Zhen; Dexter, Arthur

    2010-04-15

    A hierarchical fuzzy supervisory controller is described that is capable of optimizing the operation of a low-energy building, which uses solar energy to heat and cool its interior spaces. The highest level fuzzy rules choose the most appropriate set of lower level rules according to the weather and occupancy information; the second level fuzzy rules determine an optimal energy profile and the overall modes of operation of the heating, ventilating and air-conditioning system (HVAC); the third level fuzzy rules select the mode of operation of specific equipment, and assign schedules to the local controllers so that the optimal energy profile can be achieved in the most efficient way. Computer simulation is used to compare the hierarchical fuzzy control scheme with a supervisory control scheme based on expert rules. The performance is evaluated by comparing the energy consumption and thermal comfort. (author)

  13. A low energy beam transport system for proton beam

    SciTech Connect

    Yang, Y.; Zhang, Z. M.; Wu, Q.; Zhang, W. H.; Ma, H. Y.; Sun, L. T.; Zhang, X. Z.; Liu, Z. W.; He, Y.; Zhao, H. W.; Xie, D. Z.

    2013-03-15

    A low energy beam transport (LEBT) system has been built for a compact pulsed hadron source (CPHS) at Tsinghua University in China. The LEBT, consisting of two solenoids and three short-drift sections, transports a pulsed proton beam of 60 mA of energy of 50 keV to the entrance of a radio frequency quadrupole (RFQ). Measurement has shown a normalized RMS beam emittance less than 0.2 {pi} mm mrad at the end of the LEBT. Beam simulations were carried out to compare with the measurement and are in good agreement. Based on the successful CPHS LEBT development, a new LEBT for a China ADS projector has been designed. The features of the new design, including a beam chopper and beam simulations of the LEBT are presented and discussed along with CPHS LEBT development in this article.

  14. Scanning ion microscopy with low energy lithium ions.

    PubMed

    Twedt, Kevin A; Chen, Lei; McClelland, Jabez J

    2014-07-01

    Using an ion source based on photoionization of laser-cooled lithium atoms, we have developed a scanning ion microscope with probe sizes of a few tens of nanometers and beam energies from 500eV to 5keV. These beam energies are much lower than the typical operating energies of the helium ion microscope or gallium focused ion beam systems. We demonstrate how low energy can be advantageous in ion microscopy when detecting backscattered ions, due to a decreased interaction volume and the potential for surface sensitive composition analysis. As an example application that demonstrates these advantages, we non-destructively image the removal of a thin residual resist layer during plasma etching in a nano-imprint lithography process.

  15. Quantifying Low Energy Proton Damage in Multijunction Solar Cells

    NASA Technical Reports Server (NTRS)

    Messenger, Scott R.; Burke, Edward A.; Walters, Robert J.; Warner, Jeffrey H.; Summers, Geoffrey P.; Lorentzen, Justin R.; Morton, Thomas L.; Taylor, Steven J.

    2007-01-01

    An analysis of the effects of low energy proton irradiation on the electrical performance of triple junction (3J) InGaP2/GaAs/Ge solar cells is presented. The Monte Carlo ion transport code (SRIM) is used to simulate the damage profile induced in a 3J solar cell under the conditions of typical ground testing and that of the space environment. The results are used to present a quantitative analysis of the defect, and hence damage, distribution induced in the cell active region by the different radiation conditions. The modelling results show that, in the space environment, the solar cell will experience a uniform damage distribution through the active region of the cell. Through an application of the displacement damage dose analysis methodology, the implications of this result on mission performance predictions are investigated.

  16. Tierra concrete homes: Low-energy residential building design

    SciTech Connect

    Hayter, S.J.; Torcellini, P.A.; Neimeyer, J.

    1997-12-31

    Using a whole building design concept, Tierra Concrete Homes, a home builder in Pueblo, Colorado, created low-energy, passive solar home designs. Passive solar features incorporated into the designs include house orientation, high-mass walls for thermal storage, exterior insulation, appropriate glazing type combined with overhangs to prevent summer overheating, open interior spaces to maximize daylighting potential, and high efficiency lighting. These ranch-style homes require no cooling and minimum heating equipment to maintain comfortable indoor conditions. They are economically competitive to build, consume little fossil fuel, and produce virtually no construction waste. This paper discusses how the design of one of these homes was optimized to further minimize energy consumption while maintaining an attractive livable environment. It also describes monitoring activities that are currently underway to verify predicted energy consumption.

  17. Low energy ion beam induced changes in ETFE polymer

    NASA Astrophysics Data System (ADS)

    Parada, M. A.; Delalez, N.; de Almeida, A.; Muntele, C.; Muntele, I.; Ila, D.

    2006-01-01

    Low energy ion beam bombardment of ethylenetetrafluoroethylene (ETFE) modifies the physical and chemical properties of the polymer surface in ways that enhance or compromise applications in the technological and medical physics fields. When a material is exposed to ionizing radiation, its changes depends on the type, energy and intensity of the applied radiation. In order to determine the nature of the induced radiation changes, ETFE films were bombarded with fluences from 1012 up to 1015 ions/cm2 of keV N and protons. The emission of gaseous species during the bombardments was monitored with a residual gas analyser (RGA). The bombarded films were analysed with optical absorption photospectrometry (OAP), Fourier transform infrared (FTIR) and micro-Raman spectrometries that determine the chemical nature of the structural changes caused by ions bombardment.

  18. Milagro: A low energy threshold extensive air shower array

    SciTech Connect

    Sinnis, G.

    1992-01-01

    Milagro is a proposed extensive air shower (EAS) array with a large water Cerenkov detector at its center. It will have a low energy threshold, {approximately} 500 GeV, and good angular resolution, {approximately} 0.4{degrees}. With the large aperture and duty factor of an EAS array, and the energy threshold of an atmospheric Cerenkov telescope, it will be ideally poised to discover new, steady sources of very high energy gamma radiation similar to the Crab nebula, and transient phenomena analogous to the gamma ray bursts seen at lower energies. Here we describe the Milagro detector and give results of tests performed at the CYGNUS array that demonstrate the capabilities of the water Cerenkov technique in detecting and reconstructing extensive air showers.

  19. Milagro: A low energy threshold extensive air shower array

    SciTech Connect

    Sinnis, G.; CYGNUS and MILAGRO Collaborations

    1992-10-01

    Milagro is a proposed extensive air shower (EAS) array with a large water Cerenkov detector at its center. It will have a low energy threshold, {approximately} 500 GeV, and good angular resolution, {approximately} 0.4{degrees}. With the large aperture and duty factor of an EAS array, and the energy threshold of an atmospheric Cerenkov telescope, it will be ideally poised to discover new, steady sources of very high energy gamma radiation similar to the Crab nebula, and transient phenomena analogous to the gamma ray bursts seen at lower energies. Here we describe the Milagro detector and give results of tests performed at the CYGNUS array that demonstrate the capabilities of the water Cerenkov technique in detecting and reconstructing extensive air showers.

  20. Low energy ion beam dynamics of NANOGAN ECR ion source

    NASA Astrophysics Data System (ADS)

    Kumar, Sarvesh; Mandal, A.

    2016-04-01

    A new low energy ion beam facility (LEIBF) has been developed for providing the mass analyzed highly charged intense ion beams of energy ranging from a few tens of keV to a few MeV for atomic, molecular and materials sciences research. The new facility consists of an all permanent magnet 10 GHz electron cyclotron resonance (ECR) ion source (NANOGAN) installed on a high voltage platform (400 kV) which provides large currents of multiply charged ion beams. Higher emittance at low energy of intense ion beam puts a tremendous challenge to the beam optical design of this facility. The beam line consists of mainly the electrostatic quadrupoles, an accelerating section, analyzing cum switching magnet and suitable beam diagnostics including vacuum components. The accelerated ion beam is analyzed for a particular mass to charge (m/q) ratio as well as guided to three different lines along 75°, 90° and 105° using a large acceptance analyzing cum switching magnet. The details of transverse beam optics to all the beam lines with TRANSPORT and GICOSY beam optics codes are being described. Field computation code, OPERA 3D has been utilized to design the magnets and electrostatic quadrupoles. A theoretical estimation of emittance for optimized geometry of ion source is given so as to form the basis of beam optics calculations. The method of quadrupole scan of the beam is used to characterize the emittance of the final beam on the target. The measured beam emittance increases with m/q ratios of various ion beams similar to the trend observed theoretically.

  1. Low-Energy Impacts onto Lunar Regolith Simulant

    NASA Astrophysics Data System (ADS)

    Seward, Laura M.; Colwell, J.; Mellon, M.; Stemm, B.

    2012-10-01

    Low-Energy Impacts onto Lunar Regolith Simulant Laura M. Seward1, Joshua E. Colwell1, Michael T. Mellon2, and Bradley A. Stemm1, 1Department of Physics, University of Central Florida, Orlando, Florida, 2Southwest Research Institute, Boulder, Colorado. Impacts and cratering in space play important roles in the formation and evolution of planetary bodies. Low-velocity impacts and disturbances to planetary regolith are also a consequence of manned and robotic exploration of planetary bodies such as the Moon, Mars, and asteroids. We are conducting a program of laboratory experiments to study low-velocity impacts of 1 to 5 m/s into JSC-1 lunar regolith simulant, JSC-Mars-1 Martian regolith simulant, and silica targets under 1 g. We use direct measurement of ejecta mass and high-resolution video tracking of ejecta particle trajectories to derive ejecta mass velocity distributions. Additionally, we conduct similar experiments under microgravity conditions in a laboratory drop tower and on parabolic aircraft with velocities as low as 10 cm/s. We wish to characterize and understand the collision parameters that control the outcome of low-velocity impacts into regolith, including impact velocity, impactor mass, target shape and size distribution, regolith depth, target relative density, and crater depth, and to experimentally determine the functional dependencies of the outcomes of low-velocity collisions (ejecta mass and ejecta velocities) on the controlling parameters of the collision. We present results from our ongoing study showing the positive correlation between impact energy and ejecta mass. The total ejecta mass is also dependent on the packing density (porosity) of the regolith. We find that ejecta mass velocity fits a power-law or broken power-law distribution. Our goal is to understand the physics of ejecta production and regolith compaction in low-energy impacts and experimentally validate predictive models for dust flow and deposition. We will present our

  2. Transcanalicular laser dacryocystorhinostomy using low energy 810 nm diode laser

    PubMed Central

    Gupta, Sanjiv K.; Kumar, Ajai; Agarwal, Swati; Pandey, Paritosh

    2012-01-01

    Background: Hypertrophic scarring may be a cause of failure after transcanalicular laser dacryocystorhinostomy (DCR) surgery. This hypertrophic scarring results from tissue charring and excessive coagulation, which may be caused by the high laser energy. We have evaluated the use of low energy settings to prevent hypertrophic scarring, for a successful outcome. Aims: To perform and evaluate transcanalicular laser DCR using low energy 810 nm diode laser. Design: Interventional, non-comparative, case series. Materials and Methods: Patients with nasolacrimal duct obstruction and chronic dacryocystitis, who needed DCR, and were fit for surgery under local anesthesia, were recruited to undergo transcanalicular laser DCR using a 810 nm diode laser. The outcome was measured by the patency of the lacrimal passage, as indicated by the relief in the symptoms and the patency on syringing at the last follow-up. The surgical time and surgical complications were noted. Statistical Analysis Used: Descriptive analysis. Results: The study included 94 patients. The average age was 30.1 years (range 15 - 69 years). Seventy (74.4%) patients were female. Eight patients had failed external DCR. Per-operative patency of the passage was obtained in all the patients. Average surgical time was seven minutes (5 – 18 minutes). At the end of the study period of one year, a successful outcome was seen in 85 patients (90.5%). There were eight patients of previous failed DCR surgeries, and six of them achieved a cure at the end of follow-up. Conclusions: Transcanalicular Laser DCR can be safely performed using a low power 810 nm diode laser. The surgery is elegant, minimally invasive, allows fast rehabilitation, and has an excellent success rate. PMID:23439888

  3. Trapping low-energy antiprotons in an ion trap

    SciTech Connect

    Fei, Xiang.

    1990-01-01

    A fraction of antiprotons from the Low Energy Antiproton Ring (LEAR) of CERN are slowed from 5.9 MeV to below 3 keV as they pass through thin foils. Transmitted particle energy distribution and low energy antiproton yield are measured by a time-of-flight technique. The difference in the range of protons and antiprotons (known as the Barkas effect) is observed. While still in flight, up to 1.3 {times} 10{sup 5} antiprotons with energies between 0 eV to 3 keV are stored in an ion trap from a single pulse of 5.9 MeV antiprotons leaving LEAR, thus a trapping efficiency exceeding of 4 {times} 10{sup {minus}4} is established. Trapped antiprotons maintain their initial energy distribution unless allowed to collide with a cloud of trapped electrons, whereupon they slow and cool below 1 meV in 10 s, and fall into a harmonic potential well suited for precision mass measurements. The slowing, trapping and cooling of antiprotons are the main focus of this thesis. The stored antiprotons are in thermal equilibrium at 4.2 K. In this ion trap, the antiproton cyclotron frequency is measured and compared with the proton (or electron) cyclotron frequency. The new measured ratio of the antiproton and proton inertial masses, with its 4 {times} 10{sup {minus}8} uncertainty, is more than three orders of magnitude more accurate than previous measurements using exotic atoms. This is a most precise test of CPT invariance with baryons. The antiproton lifetime in an ion trap was measured to be more than 103 days by trapping a cloud of antiprotons for 59 days. The indicates the number density of atoms is less than 100/cm{sup 3} which corresponds to the pressure in the vacuum chamber being less than 5 {times} 10{sup {minus}17} Torr at 4.2 K if we apply the ideal gas law.

  4. Low-energy photons in high-energy photon fields--Monte Carlo generated spectra and a new descriptive parameter.

    PubMed

    Chofor, Ndimofor; Harder, Dietrich; Willborn, Kay; Rühmann, Antje; Poppe, Björn

    2011-09-01

    The varying low-energy contribution to the photon spectra at points within and around radiotherapy photon fields is associated with variations in the responses of non-water equivalent dosimeters and in the water-to-material dose conversion factors for tissues such as the red bone marrow. In addition, the presence of low-energy photons in the photon spectrum enhances the RBE in general and in particular for the induction of second malignancies. The present study discusses the general rules valid for the low-energy spectral component of radiotherapeutic photon beams at points within and in the periphery of the treatment field, taking as an example the Siemens Primus linear accelerator at 6 MV and 15 MV. The photon spectra at these points and their typical variations due to the target system, attenuation, single and multiple Compton scattering, are described by the Monte Carlo method, using the code BEAMnrc/EGSnrc. A survey of the role of low energy photons in the spectra within and around radiotherapy fields is presented. In addition to the spectra, some data compression has proven useful to support the overview of the behaviour of the low-energy component. A characteristic indicator of the presence of low-energy photons is the dose fraction attributable to photons with energies not exceeding 200 keV, termed P(D)(200 keV). Its values are calculated for different depths and lateral positions within a water phantom. For a pencil beam of 6 or 15 MV primary photons in water, the radial distribution of P(D)(200 keV) is bellshaped, with a wide-ranging exponential tail of half value 6 to 7 cm. The P(D)(200 keV) value obtained on the central axis of a photon field shows an approximately proportional increase with field size. Out-of-field P(D)(200 keV) values are up to an order of magnitude higher than on the central axis for the same irradiation depth. The 2D pattern of P(D)(200 keV) for a radiotherapy field visualizes the regions, e.g. at the field margin, where changes of

  5. Small angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Cousin, Fabrice

    2015-10-01

    Small Angle Neutron Scattering (SANS) is a technique that enables to probe the 3-D structure of materials on a typical size range lying from ˜ 1 nm up to ˜ a few 100 nm, the obtained information being statistically averaged on a sample whose volume is ˜ 1 cm3. This very rich technique enables to make a full structural characterization of a given object of nanometric dimensions (radius of gyration, shape, volume or mass, fractal dimension, specific area…) through the determination of the form factor as well as the determination of the way objects are organized within in a continuous media, and therefore to describe interactions between them, through the determination of the structure factor. The specific properties of neutrons (possibility of tuning the scattering intensity by using the isotopic substitution, sensitivity to magnetism, negligible absorption, low energy of the incident neutrons) make it particularly interesting in the fields of soft matter, biophysics, magnetic materials and metallurgy. In particular, the contrast variation methods allow to extract some informations that cannot be obtained by any other experimental techniques. This course is divided in two parts. The first one is devoted to the description of the principle of SANS: basics (formalism, coherent scattering/incoherent scattering, notion of elementary scatterer), form factor analysis (I(q→0), Guinier regime, intermediate regime, Porod regime, polydisperse system), structure factor analysis (2nd Virial coefficient, integral equations, characterization of aggregates), and contrast variation methods (how to create contrast in an homogeneous system, matching in ternary systems, extrapolation to zero concentration, Zero Averaged Contrast). It is illustrated by some representative examples. The second one describes the experimental aspects of SANS to guide user in its future experiments: description of SANS spectrometer, resolution of the spectrometer, optimization of spectrometer

  6. Local orbitals in electron scattering calculations*

    NASA Astrophysics Data System (ADS)

    Winstead, Carl L.; McKoy, Vincent

    2016-05-01

    We examine the use of local orbitals to improve the scaling of calculations that incorporate target polarization in a description of low-energy electron-molecule scattering. After discussing the improved scaling that results, we consider the results of a test calculation that treats scattering from a two-molecule system using both local and delocalized orbitals. Initial results are promising. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  7. Development of deterministic transport methods for low energy neutrons for shielding in space

    NASA Technical Reports Server (NTRS)

    Ganapol, Barry

    1993-01-01

    Transport of low energy neutrons associated with the galactic cosmic ray cascade is analyzed in this dissertation. A benchmark quality analytical algorithm is demonstrated for use with BRYNTRN, a computer program written by the High Energy Physics Division of NASA Langley Research Center, which is used to design and analyze shielding against the radiation created by the cascade. BRYNTRN uses numerical methods to solve the integral transport equations for baryons with the straight-ahead approximation, and numerical and empirical methods to generate the interaction probabilities. The straight-ahead approximation is adequate for charged particles, but not for neutrons. As NASA Langley improves BRYNTRN to include low energy neutrons, a benchmark quality solution is needed for comparison. The neutron transport algorithm demonstrated in this dissertation uses the closed-form Green's function solution to the galactic cosmic ray cascade transport equations to generate a source of neutrons. A basis function expansion for finite heterogeneous and semi-infinite homogeneous slabs with multiple energy groups and isotropic scattering is used to generate neutron fluxes resulting from the cascade. This method, called the FN method, is used to solve the neutral particle linear Boltzmann transport equation. As a demonstration of the algorithm coded in the programs MGSLAB and MGSEMI, neutron and ion fluxes are shown for a beam of fluorine ions at 1000 MeV per nucleon incident on semi-infinite and finite aluminum slabs. Also, to demonstrate that the shielding effectiveness against the radiation from the galactic cosmic ray cascade is not directly proportional to shield thickness, a graph of transmitted total neutron scalar flux versus slab thickness is shown. A simple model based on the nuclear liquid drop assumption is used to generate cross sections for the galactic cosmic ray cascade. The ENDF/B V database is used to generate the total and scattering cross sections for neutrons in

  8. Rearrangement and annihilation in antihydrogen-atom scattering

    SciTech Connect

    Jonsell, Svante

    2008-08-08

    I review some results for annihilation and rearrangement processes in low-energy antihydrogen-hydrogen and antihydrogen-helium scattering. For the strong nuclear force results using a {delta}-function potential are compared to a scattering length approach. It is found that the {delta}-function potential does not give correct annihilation cross sections in the case of antihydrogen-helium scattering. Problem associated with the use of the Born-Oppenheimer approximation for rearrangement calculations are reviewed.

  9. Coupled-channels density-matrix approach to low-energy nuclear collision dynamics: A technique for quantifying quantum decoherence effects on reaction observables

    SciTech Connect

    Diaz-Torres, Alexis

    2010-11-15

    The coupled-channels density-matrix technique for nuclear reaction dynamics, which is based on the Liouville-von Neumann equation with Lindblad dissipative terms, is developed with the inclusion of full angular momentum couplings. It allows a quantitative study of the role and importance of quantum decoherence in nuclear scattering. Formulas of asymptotic observables that can reveal effects of quantum decoherence are given. A method for extracting energy-resolved scattering information from the time-dependent density matrix is introduced. As an example, model calculations are carried out for the low-energy collision of the {sup 16}O projectile on the {sup 154}Sm target.

  10. Absolute calorimetric calibration of low energy brachytherapy sources

    NASA Astrophysics Data System (ADS)

    Stump, Kurt E.

    In the past decade there has been a dramatic increase in the use of permanent radioactive source implants in the treatment of prostate cancer. A small radioactive source encapsulated in a titanium shell is used in this type of treatment. The radioisotopes used are generally 125I or 103Pd. Both of these isotopes have relatively short half-lives, 59.4 days and 16.99 days, respectively, and have low-energy emissions and a low dose rate. These factors make these sources well suited for this application, but the calibration of these sources poses significant metrological challenges. The current standard calibration technique involves the measurement of ionization in air to determine the source air-kerma strength. While this has proved to be an improvement over previous techniques, the method has been shown to be metrologically impure and may not be the ideal means of calbrating these sources. Calorimetric methods have long been viewed to be the most fundamental means of determining source strength for a radiation source. This is because calorimetry provides a direct measurement of source energy. However, due to the low energy and low power of the sources described above, current calorimetric methods are inadequate. This thesis presents work oriented toward developing novel methods to provide direct and absolute measurements of source power for low-energy low dose rate brachytherapy sources. The method is the first use of an actively temperature-controlled radiation absorber using the electrical substitution method to determine total contained source power of these sources. The instrument described operates at cryogenic temperatures. The method employed provides a direct measurement of source power. The work presented here is focused upon building a metrological foundation upon which to establish power-based calibrations of clinical-strength sources. To that end instrument performance has been assessed for these source strengths. The intent is to establish the limits of

  11. Suppression of Quantum Scattering in Strongly Confined Systems

    SciTech Connect

    Kim, J. I.; Melezhik, V. S.; Schmelcher, P.

    2006-11-10

    We demonstrate that scattering of particles strongly interacting in three dimensions (3D) can be suppressed at low energies in a quasi-one-dimensional (1D) confinement. The underlying mechanism is the interference of the s- and p-wave scattering contributions with large s- and p-wave 3D scattering lengths being a necessary prerequisite. This low-dimensional quantum scattering effect might be useful in 'interacting' quasi-1D ultracold atomic gases, guided atom interferometry, and impurity scattering in strongly confined quantum wire-based electronic devices.

  12. Atom-molecule scattering with the average wavefunction method

    NASA Astrophysics Data System (ADS)

    Singh, Harjinder; Dacol, Dalcio K.; Rabitz, Herschel

    1987-08-01

    The average wavefunction method (AWM) is applied to atom-molecule scattering. In its simplest form the labor involved in solving the AWM equations is equivalent to that involved for elastic scattering in the same formulation. As an initial illustration, explicit expressions for the T-matrix are derived for the scattering of an atom and a rigid rotor. Results are presented for low-energy scattering and corrections to the Born approximation are clearly evident. In general, the AWM is particularly suited to polyatom scattering due to its reduction of the potential in terms of a separable atom-atom potential.

  13. Testing SO(10)-inspired leptogenesis with low energy neutrino experiments

    SciTech Connect

    Bari, Pasquale Di; Riotto, Antonio E-mail: Antonio.Riotto@cern.ch

    2011-04-01

    We extend the results of a previous analysis of ours showing that, when both heavy and light flavour effects are taken into account, successful minimal (type I + thermal) leptogenesis with SO(10)-inspired relations is possible. Barring fine tuned choices of the parameters, these relations enforce a hierarchical RH neutrino mass spectrum that results into a final asymmetry dominantly produced by the next-to-lightest RH neutrino decays (N{sub 2} dominated leptogenesis). We present the constraints on the whole set of low energy neutrino parameters. Allowing a small misalignment between the Dirac basis and the charged lepton basis as in the quark sector, the allowed regions enlarge and the lower bound on the reheating temperature gets relaxed to values as low as ∼ 10{sup 10} GeV. It is confirmed that for normal ordering (NO) there are two allowed ranges of values for the lightest neutrino mass: m{sub 1} ≅ (1−5) × 10{sup −3} eV and m{sub 1} ≅ (0.03−0.1) eV. For m{sub 1}∼<0.01 eV the allowed region in the plane θ{sub 13}-θ{sub 23} is approximately given by θ{sub 23}∼<49°+0.65 (θ{sub 13}−5°), while the neutrinoless double beta decay effective neutrino mass falls in the range m{sub ee} = (1−3) × 10{sup −3} eV for θ{sub 13} = (6°−11.5°). For m{sub 1}∼>0.01 eV, one has quite sharply m{sub ee} ≅ m{sub 1} and an upper bound θ{sub 23}∼<46°. These constraints will be tested by low energy neutrino experiments during next years. We also find that inverted ordering (IO), though quite strongly constrained, is not completely ruled out. In particular, we find approximately θ{sub 23} ≅ 43°+12° log (0.2 eV/m{sub 1}), that will be fully tested by future experiments.

  14. Sensitizing DNA Towards Low-Energy Electrons with 2-Fluoroadenine.

    PubMed

    Rackwitz, Jenny; Kopyra, Janina; Dąbkowska, Iwona; Ebel, Kenny; Ranković, MiloŠ Lj; Milosavljević, Aleksandar R; Bald, Ilko

    2016-08-22

    2-Fluoroadenine ((2F) A) is a therapeutic agent, which is suggested for application in cancer radiotherapy. The molecular mechanism of DNA radiation damage can be ascribed to a significant extent to the action of low-energy (<20 eV) electrons (LEEs), which damage DNA by dissociative electron attachment. LEE induced reactions in (2F) A are characterized both isolated in the gas phase and in the condensed phase when it is incorporated into DNA. Information about negative ion resonances and anion-mediated fragmentation reactions is combined with an absolute quantification of DNA strand breaks in (2F) A-containing oligonucleotides upon irradiation with LEEs. The incorporation of (2F) A into DNA results in an enhanced strand breakage. The strand-break cross sections are clearly energy dependent, whereas the strand-break enhancements by (2F) A at 5.5, 10, and 15 eV are very similar. Thus, (2F) A can be considered an effective radiosensitizer operative at a wide range of electron energies. PMID:27481662

  15. Low energy, high power hydrogen neutral beam for plasma heating

    SciTech Connect

    Deichuli, P.; Davydenko, V.; Ivanov, A. Mishagin, V.; Sorokin, A.; Stupishin, N.; Korepanov, S.; Smirnov, A.

    2015-11-15

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  16. ELISA - an electrostatic storage ring for low-energy ions

    NASA Astrophysics Data System (ADS)

    Pape Moeller, Soeren

    1997-05-01

    The design of a new type of storage ring for low-energy ions using electrostatic deflection and focusing devices is described. Electrostatic bends and quadrupoles are used since they are more efficient than magnetic ones for low-velocity heavy ions. Furthermore, electrostatic devices are more compact and easier to construct than magnetic devices. In comparison to an electromagnetic trap, one important advantage of the elecrostatic ring is the easy access to the circulating beam and its decay products. These and other features, e.g. no magnetic fields, makes such storage devices attractive for many atomic-physics experiments. Also neigboring fields as chemistry and biology might benefit from such an relatively inexpensive device. One important difference between an electrostatic and a magnetic ring is, that the longitudinal energy is not conserved for the electrostatic ring. The actual ring will have a race-track shape as defined by two straight sections each with two quadrupole doublets connected by 180-degrees bends. The bends will consist of 160-degrees spherical deflection plates surrounded by two parallel plate 10-degrees bends. The storage ring ELISA, currently being built, will have a circumference of 6 meters. The first beam tests will take place during summer 1996.

  17. Vacancy-Induced Low-Energy States in Undoped Graphene.

    PubMed

    Sanyal, Sambuddha; Damle, Kedar; Motrunich, Olexei I

    2016-09-01

    We demonstrate that a nonzero concentration n_{v} of static, randomly placed vacancies in graphene leads to a density w of zero-energy quasiparticle states at the band center ε=0 within a tight-binding description with nearest-neighbor hopping t on the honeycomb lattice. We show that w remains generically nonzero in the compensated case (exactly equal number of vacancies on the two sublattices) even in the presence of hopping disorder and depends sensitively on n_{v} and correlations between vacancy positions. For low, but not-too-low, |ε|/t in this compensated case, we show that the density of states ρ(ε) exhibits a strong divergence of the form ρ_{Dyson}(ε)∼|ε|^{-1}/[log(t/|ε|)]^{(y+1)}, which crosses over to the universal low-energy asymptotic form (modified Gade-Wegner scaling) expected on symmetry grounds ρ_{GW}(ε)∼|ε|^{-1}e^{-b[log(t/|ε|)]^{2/3}} below a crossover scale ε_{c}≪t. ε_{c} is found to decrease rapidly with decreasing n_{v}, while y decreases much more slowly. PMID:27661714

  18. [Progress of low-energy shockwave therapy in clinical application].

    PubMed

    Xin, Zhong-cheng; Liu, Jing; Wang, Lin; Li, Hui-xi

    2013-08-18

    A shock wave is a transient pressure disturbance that propagates rapidly in three-dimensional space. It is associated with a sudden rise from ambient pressure to its maximum pressure. Shock wave therapy in urology is primarily used to disintegrate urolithiasis. Recently, low-energy shock wave therapy (LESWT), which is a novel convenient and cost-effective therapeutic modality, is extended to treat other pathological conditions including coronary heart disease, musculoskeletal disorders and erectile dysfunction. However, the exact therapeutic mechanisms and clinical safety and efficacy of LESWT remain to be investigated. Based on the results of previous studies, it is suggested that LESWT could regulate angiogenesis-related growth factors expression including endothelial nitric oxide synthase (eNOS), vessel endothelial growth factor (VEGF) and proliferating cell nuclear antigen (PCNA), which might induce the ingrowth of neovascularization that improves blood supply and increases cell proliferation and eventual tissue regeneration for restore pathological changes. The further studies on cellular and molecular biological changes by LESWT for clarification its mechanism and clinical safety and efficacy studies are recommended.

  19. Options for Production Staging for a Low Energy Neutrino Factory

    SciTech Connect

    Berg J. S.

    2011-10-26

    A low energy neutrino factory (LENF) is defined, for the purpose of this report, to accelerate a muon beam to a total energy in the range of 10-14 GeV, and store it in a decay ring directing a resulting neutrino beam to a detector 2200-2300 km distant. The machine should be ultimately capable of producing 10{sup 21} decays toward that detector per year of 10{sup 7} s. We consider such a neutrino factory to be the accelerator defined in the Interim Design Report (IDR) of the International Design Study for the Neutrino Factory (IDS-NF), modified to remove the final stage of acceleration, possibly modifying the remaining acceleration stages to adjust the final energy, and replacing the decay ring with one designed for the lower energy and shorter baseline. We discuss modifications to that design which would reduce the cost of the machine at the price of a reduction in neutrino production, down to as low as 10{sup 20} decays per year. These modifications will not preclude eventually upgrading the machine to the full production of 10{sup 21} decays per year. The eventual cost of a machine which achieves the full production through a series of lower-production stages should not exceed the cost of a machine which is immediately capable of the full production by more than a small fraction of the cost difference between the full production machine and the lowest production stage.

  20. Addressing Kitchen Contaminants for Healthy, Low-Energy Homes

    SciTech Connect

    Stratton, J. Chris; Singer, Brett C.

    2014-01-01

    Cooking and cooking burners emit pollutants that can adversely affect indoor air quality in residences and significantly impact occupant health. Effective kitchen exhaust ventilation can reduce exposure to cooking-related air pollutants as an enabling step to healthier, low-energy homes. This report identifies barriers to the widespread adoption of kitchen exhaust ventilation technologies and practice and proposes a suite of strategies to overcome these barriers. The recommendations have been vetted by a group of industry, regulatory, health, and research experts and stakeholders who convened for two web-based meetings and provided input and feedback to early drafts of this document. The most fundamental barriers are (1) the common misconception, based on a sensory perception of risk, that kitchen exhaust when cooking is unnecessary and (2) the lack of a code requirement for kitchen ventilation in most US locations. Highest priority objectives include the following: (1) Raise awareness among the public and the building industry of the need to install and routinely use kitchen ventilation; (2) Incorporate kitchen exhaust ventilation as a requirement of building codes and improve the mechanisms for code enforcement; (3) Provide best practice product and use-behavior guidance to ventilation equipment purchasers and installers, and; (4) Develop test methods and performance targets to advance development of high performance products. A specific, urgent need is the development of an over-the-range microwave that meets the airflow and sound requirements of ASHRAE Standard 62.2.

  1. Addressing Kitchen Contaminants for Healthy, Low-Energy Homes

    SciTech Connect

    Stratton, J. Chris; Singer, Brett C.

    2014-01-01

    Cooking and cooking burners emit pollutants that can adversely affect indoor air quality in residences and significantly impact occupant health. Effective kitchen exhaust ventilation can reduce exposure to cooking-related air pollutants as an enabling step to healthier, low-energy homes. This report by Lawrence Berkeley National Laboratory identifies barriers to the widespread adoption of kitchen exhaust ventilation technologies and practice and proposes a suite of strategies to overcome these barriers. The recommendations have been vetted by a group of industry, regulatory, health, and research experts and stakeholders who convened for two meetings and provided input and feedback to early drafts of this document. The most fundamental barriers are (1) the common misconception, based on a sensory perception of risk, that kitchen exhaust when cooking is unnecessary and (2) the lack of a code requirement for kitchen ventilation in most U.S. locations. Highest priority objectives include the following: (1) Raise awareness among the public and the building industry of the need to install and routinely use kitchen ventilation; (2) Incorporate kitchen exhaust ventilation as a requirement of building codes and improve the mechanisms for code enforcement; (3) Provide best practice product and use-behavior guidance to ventilation equipment purchasers and installers, and; (4) Develop test methods and performance targets to advance development of high performance products. A specific, urgent need is the development of an over-the-range microwave that meets the airflow and sound requirements of ASHRAE Standard 62.2.

  2. A compact, versatile low-energy electron beam ion source

    SciTech Connect

    Zschornack, G.; König, J.; Schmidt, M.; Thorn, A.

    2014-02-15

    A new compact Electron Beam Ion Source, the Dresden EBIT-LE, is introduced as an ion source working at low electron beam energies. The EBIT-LE operates at an electron energy ranging from 100 eV to some keV and can easily be modified to an EBIT also working at higher electron beam energies of up to 15 keV. We show that, depending on the electron beam energy, electron beam currents from a few mA in the low-energy regime up to about 40 mA in the high-energy regime are possible. Technical solutions as well as first experimental results of the EBIT-LE are presented. In ion extraction experiments, a stable production of low and intermediate charged ions at electron beam energies below 2 keV is demonstrated. Furthermore, X-ray spectroscopy measurements confirm the possibility of using the machine as a source of X-rays from ions excited at low electron energies.

  3. Theories of Variable Mass Particles and Low Energy Nuclear Phenomena

    NASA Astrophysics Data System (ADS)

    Davidson, Mark

    2014-02-01

    Variable particle masses have sometimes been invoked to explain observed anomalies in low energy nuclear reactions (LENR). Such behavior has never been observed directly, and is not considered possible in theoretical nuclear physics. Nevertheless, there are covariant off-mass-shell theories of relativistic particle dynamics, based on works by Fock, Stueckelberg, Feynman, Greenberger, Horwitz, and others. We review some of these and we also consider virtual particles that arise in conventional Feynman diagrams in relativistic field theories. Effective Lagrangian models incorporating variable mass particle theories might be useful in describing anomalous nuclear reactions by combining mass shifts together with resonant tunneling and other effects. A detailed model for resonant fusion in a deuterium molecule with off-shell deuterons and electrons is presented as an example. Experimental means of observing such off-shell behavior directly, if it exists, is proposed and described. Brief explanations for elemental transmutation and formation of micro-craters are also given, and an alternative mechanism for the mass shift in the Widom-Larsen theory is presented. If variable mass theories were to find experimental support from LENR, then they would undoubtedly have important implications for the foundations of quantum mechanics, and practical applications may arise.

  4. Resonant Electromagnetic Interaction in Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Chubb, Scott

    2008-03-01

    Basic ideas about how resonant electromagnetic interaction (EMI) can take place in finite solids are reviewed. These ideas not only provide a basis for conventional, electron energy band theory (which explains charge and heat transport in solids), but they also explain how through finite size effects, it is possible to create many of the kinds of effects envisioned by Giuliano Preparata. The underlying formalism predicts that the orientation of the external fields in the SPAWAR protocolootnotetextKrivit, Steven B., New Energy Times, 2007, issue 21, item 10. http://newenergytimes.com/news/2007/NET21.htm^,ootnotetextSzpak, S.; Mosier-Boss, P.A.; Gordon, F.E. Further evidence of nuclear reactions in the Pd lattice: emission of charged particles. Naturwissenschaften 94,511(2007)..has direct bearing on the emission of high-energy particles. Resonant EMI also implies that nano-scale solids, of a particular size, provide an optimal environment for initiating Low Energy Nuclear Reactions (LENR) in the PdD system.

  5. A high intensity dc H- source for low energy injection

    NASA Astrophysics Data System (ADS)

    Kuo, T.; Baartman, R.; Dutto, G.; Hahto, S.; ńrje, J.; Liukkonen, E.

    2002-02-01

    While a 20 mA dc H- source system at 25-30 keV beam energy has been developed at TRIUMF several years ago, another recent demand on the system is to provide a 4 to 5 mA H- at the 4-6 keV energy range. We found that at this low energy range, the existing source/extraction system can only give ˜1 mA with poor emittance due to strong space-charge effect. Fortunately, a very special source/extraction mechanism together with the use of neutralization was discovered and developed to overcome this difficulty. Up to 4 mA with a normalized rms emittance of 0.15 π mm mr has been achieved at 6 keV. This performance finds its usefulness for injection systems where lower beam energy and higher beam intensity are required. A copy of the TRIUMF system was constructed and successfully tested in the summer of 2000 for the "H- Acceleration Project" for the K130 cyclotron at Jyväskylä University, Finland.

  6. Low energy booster radio frequency cavity structural analysis

    SciTech Connect

    Jones, K.

    1993-04-01

    The structural design of the Superconducting Super Collider Low Energy Booster (LEB) Radio Frequency (RF) Cavity is very unique. The cavity is made of three different materials which all contribute to its structural strength while at the same time providing a good medium for magnetic properties. Its outer conductor is made of thin walled stainless steel which is later copper plated to reduce the electrical losses. Its tuner housing is made of a fiber reinforced composite laminate, similar to G10, glued to stainless steel plating. The stainless steel of the tuner is slotted to significantly diminish the magnetically-induced eddy currents. The composite laminate is bonded to the stainless steel to restore the structural strength that was lost in slotting. The composite laminate is also a barrier against leakage of the pressurized internal ferrite coolant fluid. The cavity`s inner conductor, made of copper and stainless steel, is subjected to high heat loads and must be liquid cooled. The requirements of the Cavity are very stringent and driven primarily by deflection, natural frequency and temperature. Therefore, very intricate finite element analysis was used to complement conventional hand analysis in the design of the cavity. Structural testing of the assembled prototype cavity is planned to demonstrate the compliance of the cavity design to all of its requirements.

  7. Rydberg phases of Hydrogen and low energy nuclear reactions

    NASA Astrophysics Data System (ADS)

    Olafsson, Sveinn; Holmlid, Leif

    2016-03-01

    For over the last 26 years the science of cold fusion/LENR has been researched around the world with slow pace of progress. Modest quantity of excess heat and signatures of nuclear transmutation and helium production have been confirmed in experiments and theoretical work has only resulted in a large flora of inadequate theoretical scenarios. Here we review current state of research in Rydberg matter of Hydrogen that is showing strong signature of nuclear processes. In the presentation experimental behavior of Rydberg matter of hydrogen is described. An extensive collaboration effort of surface physics, catalysis, atomic physics, solid state physics, nuclear physics and quantum information is need to tackle the surprising experimental results that have so far been obtained. Rydberg matter of Hydrogen is the only known state of matter that is able to bring huge collection of protons to so short distances and for so long time that tunneling becomes a reasonable process for making low energy nuclear reactions. Nuclear quantum entanglement can also become realistic process at theses conditions.

  8. Low energy electrons and swift ion track structure in PADC

    DOE PAGES

    Fromm, Michel; Quinto, Michele A.; Weck, Philippe F.; Champion, Christophe

    2015-05-27

    The current work aims at providing an accurate description of the ion track-structure in poly-allyl dyglycol carbonate (PADC) by using an up-to-date Monte-Carlo code-called TILDA-V (a French acronym for Transport d’Ions Lourds Dans l’Aqua & Vivo). In this simulation the ion track-structure in PADC is mainly described in terms of ejected electrons with a particular attention done to the Low Energy Electrons (LEEs). After a brief reminder of the most important channels through which LEEs are prone to break a chemical bond, we will report on the simulated energetic distributions of LEEs along an ion track in PADC for particularmore » incident energies located on both sides of the Bragg-peak position. Lastly, based on the rare data dealing with LEEs interaction with polymers or organic molecules, we will emphasise the role played by the LEEs in the formation of a latent track in PADC, and more particularly the one played by the sub-ionization electrons.« less

  9. Heliosphere Instrument for Spectra, Composition and Anisotropy at Low Energies

    NASA Technical Reports Server (NTRS)

    Lanzerotti, L. J.; Gold, R. E.; Anderson, K. A.; Armstrong, T. P.; Lin, R. P.; Krimigis, S. M.; Pick, M.; Roelof, E. C.; Sarris, E. T.; Simnett, G. M.

    1992-01-01

    The Heliosphere Instrument for Spectra, Composition, and Anisotropy at Low Energies (HI-SCALE) is designed to make measurements of interplanetary ions and electrons throughout the entire Ulysses mission. The ions (E(i) greater than about 50 keV) and electrons (E(e) greater than about 30 keV) are identified uniquely and detected by five separate solid-state detector telescopes that are oriented to give nearly complete pitch-angle coverage from the spinning spacecraft. Ion elemental abundances are determined by Delta E vs E telescope using a thin (5 microns) front solid state detector element in a three-element telescope. Experimental operation is controlled by a microprocessor-based data system. Inflight calibration is provided by radioactive sources mounted on telescope covers which can be closed for calibration purposes and for radiation protection during the course of the mission. Ion and electron spectral information is determined using both broad-energy-range rate channels and a 32 channel pulse-height analyzer for more detailed spectra. Some initial in-ecliptic measurements are presented which demonstrate the features of the instrument.

  10. Effects of low-energy shock waves on oral bacteria.

    PubMed

    Novak, K F; Govindaswami, M; Ebersole, J L; Schaden, W; House, N; Novak, M J

    2008-10-01

    We have recently demonstrated that extracorporeal shock-wave therapy (ESWT) is effective in promoting the healing of dermal wounds and in regenerating alveolar bone lost through periodontal disease. The objective of the present study was to determine any antibacterial effect of ESWT on oral bacteria. Monoculture suspensions of 6 bacterial species were treated with 100 to 500 pulses of ESWT at energy flux densities (EFD) of 0.12 mJ/mm(2), 0.22 mJ/mm(2), and 0.3 mJ/mm(2). Following treatment, aliquots were plated for viability determination and compared with untreated controls. ESWT showed a significant microbicidal effect for Streptococcus mutans and an unencapsulated strain of Porphyromonas gingivalis following as few as 100 pulses at 0.3 mJ/mm(2) (p 0.05). These findings suggest that low-energy ESWT may be bactericidal for selected oral bacteria.

  11. Low-energy gamma ray attenuation characteristics of aviation fuels

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Shen, Chih-Ping; Sprinkle, Danny R.

    1990-01-01

    Am241 (59.5 keV) gamma ray attenuation characteristics were investigated in 270 aviation fuel (Jet A and Jet A-1) samples from 76 airports around the world as a part of world wide study to measure the variability of aviation fuel properties as a function of season and geographical origin. All measurements were made at room temperature which varied from 20 to 27 C. Fuel densities (rho) were measured concurrently with their linear attenuation coefficients (mu), thus providing a measure of mass attenuation coefficient (mu/rho) for the test samples. In 43 fuel samples, rho and mu values were measured at more than one room temperature, thus providing mu/rho values for them at several temperatures. The results were found to be independent of the temperature at which mu and rho values were measured. It is noted that whereas the individual mu and rho values vary considerably from airport to airport as well as season to season, the mu/rho values for all samples are constant at 0.1843 + or - 0.0013 cu cm/gm. This constancy of mu/rho value for aviation fuels is significant since a nuclear fuel quantity gauging system based on low energy gamma ray attenuation will be viable throughout the world.

  12. Photon strength and the low-energy enhancement

    NASA Astrophysics Data System (ADS)

    Wiedeking, M.; Bernstein, L. A.; Krtička, M.; Bleuel, D. L.; Allmond, J. M.; Basunia, M. S.; Burke, J. T.; Fallon, P.; Firestone, R. B.; Goldblum, B. L.; Hatarik, R.; Lake, P. T.; Lee, I.-Y.; Lesher, S. R.; Paschalis, S.; Petri, M.; Phair, L.; Scielzo, N. D.

    2014-08-01

    Several measurements in medium mass nuclei have reported a low-energy enhancement in the photon strength function. Although, much effort has been invested in unraveling the mysteries of this effect, its physical origin is still not conclusively understood. Here, a completely model-independent experimental approach to investigate the existence of this enhancement is presented. The experiment was designed to study statistical feeding from the quasi-continuum (below the neutron separation energy) to individual low-lying discrete levels in 95Mo produced in the (d, p) reaction. A key aspect to successfully study gamma decay from the region of high-level density is the detection and extraction of correlated particle-gamma-gamma events which was accomplished using an array of Clover HPGe detectors and large area annular silicon detectors. The entrance channel excitation energy into the residual nucleus produced in the reaction was inferred from the detected proton energies in the silicon detectors. Gating on gamma-transitions originating from low-lying discrete levels specifies the state fed by statistical gamma-rays. Any particle-gamma-gamma event in combination with specific energy sum requirements ensures a clean and unambiguous determination of the initial and final state of the observed gamma rays. With these requirements the statistical feeding to individual discrete levels is extracted on an event-by-event basis. The results are presented and compared to 95Mo photon strength function data measured at the University of Oslo.

  13. Photon strength and the low-energy enhancement

    SciTech Connect

    Wiedeking, M.; Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Hatarik, R.; Lesher, S. R.; Scielzo, N. D.; Krtička, M.; Allmond, J. M.; Basunia, M. S.; Fallon, P.; Firestone, R. B.; Lake, P. T.; Lee, I-Y.; Paschalis, S.; Petri, M.; Phair, L.; Goldblum, B. L.

    2014-08-14

    Several measurements in medium mass nuclei have reported a low-energy enhancement in the photon strength function. Although, much effort has been invested in unraveling the mysteries of this effect, its physical origin is still not conclusively understood. Here, a completely model-independent experimental approach to investigate the existence of this enhancement is presented. The experiment was designed to study statistical feeding from the quasi-continuum (below the neutron separation energy) to individual low-lying discrete levels in {sup 95}Mo produced in the (d, p) reaction. A key aspect to successfully study gamma decay from the region of high-level density is the detection and extraction of correlated particle-gamma-gamma events which was accomplished using an array of Clover HPGe detectors and large area annular silicon detectors. The entrance channel excitation energy into the residual nucleus produced in the reaction was inferred from the detected proton energies in the silicon detectors. Gating on gamma-transitions originating from low-lying discrete levels specifies the state fed by statistical gamma-rays. Any particle-gamma-gamma event in combination with specific energy sum requirements ensures a clean and unambiguous determination of the initial and final state of the observed gamma rays. With these requirements the statistical feeding to individual discrete levels is extracted on an event-by-event basis. The results are presented and compared to {sup 95}Mo photon strength function data measured at the University of Oslo.

  14. Seeking to Improve Low Energy Neutral Atom Detection in Space

    NASA Technical Reports Server (NTRS)

    Shappirio, M.; Coplan, M.; Chornay, D.; Collier, M.; Herrero, F.; Ogilvie, K.; Williams, E.

    2007-01-01

    The detection of energetic neutral atoms allows for the remote examination of the interactions between plasmas and neutral populations in space. Before these neutral atoms can be measured, they must first be converted to ions. For the low energy end of this spectrum, interaction with a conversion surface is often the most efficient method to convert neutrals into ions. It is generally thought that the most efficient surfaces are low work functions materials. However, by their very nature, these surfaces are highly reactive and unstable, and therefore are not suitable for space missions where conditions cannot be controlled as they are in a laboratory. We therefore are looking to optimize a stable surface for conversion efficiency. Conversion efficiency can be increased either by changing the incident angle of the neutral particles to be grazing incidence and using stable surfaces with high conversion efficiencies. We have examined how to increase the angle of incidence from -80 degrees to -89 degrees, while maintaining or improving the total active conversion surface area without increasing the overall volume of the instrument. We are developing a method to micro-machine silicon, which will reduce the volume to surface area ratio by a factor of 60. We have also examined the material properties that affect the conversion efficiency of the surface for stable surfaces. Some of the parameters we have examined are work function, smoothness, and bond structure. We find that for stable surfaces, the most important property is the smoothness of the surface.

  15. Analysis of latency performance of bluetooth low energy (BLE) networks.

    PubMed

    Cho, Keuchul; Park, Woojin; Hong, Moonki; Park, Gisu; Cho, Wooseong; Seo, Jihoon; Han, Kijun

    2014-12-23

    Bluetooth Low Energy (BLE) is a short-range wireless communication technology aiming at low-cost and low-power communication. The performance evaluation of classical Bluetooth device discovery have been intensively studied using analytical modeling and simulative methods, but these techniques are not applicable to BLE, since BLE has a fundamental change in the design of the discovery mechanism, including the usage of three advertising channels. Recently, there several works have analyzed the topic of BLE device discovery, but these studies are still far from thorough. It is thus necessary to develop a new, accurate model for the BLE discovery process. In particular, the wide range settings of the parameters introduce lots of potential for BLE devices to customize their discovery performance. This motivates our study of modeling the BLE discovery process and performing intensive simulation. This paper is focused on building an analytical model to investigate the discovery probability, as well as the expected discovery latency, which are then validated via extensive experiments. Our analysis considers both continuous and discontinuous scanning modes. We analyze the sensitivity of these performance metrics to parameter settings to quantitatively examine to what extent parameters influence the performance metric of the discovery processes.

  16. Review of lattice results concerning low-energy particle physics

    DOE PAGES

    Aoki, S.; Aoki, Y.; Bernard, C.; Blum, T.; Colangelo, G.; Della Morte, M.; Dürr, S.; El-Khadra, A. X.; Fukaya, H.; Horsley, R.; et al

    2014-09-01

    We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle physics community. More specifically, we report on the determination of the light-quark masses, the form factor f+(0), arising in semileptonic K -> pi transition at zero momentum transfer, as well as the decay constant ratio fK/fpi of decay constants and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)LxSU(2)R and SU(3)LxSU(3)R Chiral Perturbation Theory and review the determination ofmore » the BK parameter of neutral kaon mixing. The inclusion of heavy-quark quantities significantly expands the FLAG scope with respect to the previous review. Therefore, for this review, we focus on D- and B-meson decay constants, form factors, and mixing parameters, since these are most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. In addition we review the status of lattice determinations of the strong coupling constant alpha_s.« less

  17. Low-energy theory of transport in Majorana wire junctions

    NASA Astrophysics Data System (ADS)

    Zazunov, A.; Egger, R.; Levy Yeyati, A.

    2016-07-01

    We formulate and apply a low-energy transport theory for hybrid quantum devices containing junctions of topological superconductor (TS) wires and conventional normal (N) or superconducting (S) leads. We model TS wires as spinless p -wave superconductors and derive their boundary Keldysh Green's function, capturing both the Majorana end state and continuum quasiparticle excitations in a unified manner. We also specify this Green's function for a finite-length TS wire. Junctions connecting different parts of the device are described by the standard tunneling Hamiltonian. Using this Hamiltonian approach, one also has the option to include many-body interactions in a systematic manner. For N-TS junctions, we provide the current-voltage (I -V ) characteristics at arbitrary junction transparency and give exact results for the shot-noise power and the excess current. For TS-TS junctions, analytical results for the thermal noise spectrum and for the I -V curve in the high-transparency low-bias regime are presented. For S-TS junctions, we compute the entire I -V curve and clarify the conditions for having a finite Josephson current.

  18. Low energy, high power hydrogen neutral beam for plasma heating.

    PubMed

    Deichuli, P; Davydenko, V; Ivanov, A; Korepanov, S; Mishagin, V; Smirnov, A; Sorokin, A; Stupishin, N

    2015-11-01

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  19. Sparse + low-energy decomposition for viscous conservation laws

    NASA Astrophysics Data System (ADS)

    Hou, Thomas Y.; Li, Qin; Schaeffer, Hayden

    2015-05-01

    For viscous conservation laws, solutions contain smooth but high-contrast features, which require the use of fine grids to properly resolve. On coarse grids, these high-contrast jumps resemble shocks rather than their true viscous profiles, which could lead to issues in the numerical approximation of their underlying dynamics. In many cases, the equations of motion emit traveling wave solutions which can be used to represent the viscous profiles analytically. The traveling wave solutions can be thought of as a lower dimensional representation of the motion, since they contain information from the evolution equation, but are constant along certain time-space curves. Using a parameterized basis involving the traveling waves, along with the sparse + low-energy decompositions found in imaging sciences, we propose an approximation to viscous conservation laws which separates the coarse smooth component from the sharp fine one. Our method provides an appropriate approximation to the solution on a coarse grid, thereby accurately under-resolving the viscous profile. This is similar to the philosophy of shock capturing methods, in the sense that we want to capture the viscous front without needing to resolve the profile. Theoretical results on the consistency of our method are shown in general. We provide several computational examples for convex and non-convex fluxes.

  20. Low energy, high power hydrogen neutral beam for plasma heating

    NASA Astrophysics Data System (ADS)

    Deichuli, P.; Davydenko, V.; Ivanov, A.; Korepanov, S.; Mishagin, V.; Smirnov, A.; Sorokin, A.; Stupishin, N.

    2015-11-01

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  1. Ultra-low-energy analog straintronics using multiferroic composites

    NASA Astrophysics Data System (ADS)

    Roy, Kuntal

    2014-03-01

    Multiferroic devices, i.e., a magnetostrictive nanomagnet strain-coupled with a piezoelectric layer, are promising as binary switches for ultra-low-energy digital computing in beyond Moore's law era [Roy, K. Appl. Phys. Lett. 103, 173110 (2013), Roy, K. et al. Appl. Phys. Lett. 99, 063108 (2011), Phys. Rev. B 83, 224412 (2011), Scientific Reports (Nature Publishing Group) 3, 3038 (2013), J. Appl. Phys. 112, 023914 (2012)]. We show here that such multiferroic devices, apart from performing digital computation, can be also utilized for analog computing purposes, e.g., voltage amplification, filter etc. The analog computing capability is conceived by considering that magnetization's mean orientation shifts gradually although nanomagnet's potential minima changes abruptly. Using tunneling magnetoresistance (TMR) measurement, a continuous output voltage while varying the input voltage can be produced. Stochastic Landau-Lifshitz-Gilbert (LLG) equation in the presence of room-temperature (300 K) thermal fluctuations is solved to demonstrate the analog computing capability of such multiferroic devices. This work was supported in part by FAME, one of six centers of STARnet, a Semiconductor Research Corporation program sponsored by MARCO and DARPA.

  2. Biophysics behavior of acupuncture points irradiated with low energy lasers.

    PubMed

    Moldovan, C

    2007-01-01

    This work describes the Low Energy Laser (LEL) coherent light interaction with the skin cover on acupuncture loci for the purpose of detecting and measuring the spatial and temporal alteration of the thermal, electric and optical properties of the LI4 (HEGU) acupoint, irradiated with a 685 nm, 30 mW, III.B Laser. Novel electrostatic imaging technique, an original Acupuncture 3-D Thermal and Electric Mapping Technique and an original Method for Laser-Skin Reflectance, were used in the study. The results indicate that the visible laser light, with low frequency and low power, specifically modify the 3-D pattern of the temperature, electric potential and electric impedance outline of an acupuncture point, meanwhile with a significant decrease of the laser reflectance index, all measured on a 27 apparently healthy subject lot (48 years mean age, 54% male), when comparing with a non-active, non-acupunctural skin area, placed on the volar side of the same hand. The biophysical method presented, combines in a complex way and reproducible the electro stasis exploration (bioelectric homeostasis), with cutaneous thermodynamic exploration and photo-optical exploration of the derma and provides information that can be appreciated in dynamics and compared depending on the exploration target.

  3. Review of lattice results concerning low-energy particle physics

    SciTech Connect

    Aoki, S.; Aoki, Y.; Bernard, C.; Blum, T.; Colangelo, G.; Della Morte, M.; Dürr, S.; El-Khadra, A. X.; Fukaya, H.; Horsley, R.; Jüttner, A.; Kaneko, T.; Laiho, J.; Lellouch, L.; Leutwyler, H.; Lubicz, V.; Lunghi, E.; Necco, S.; Onogi, T.; Pena, C.; Sachrajda, C. T.; Sharpe, S. R.; Simula, S.; Sommer, R.; Van de Water, R. S.; Vladikas, A.; Wenger, U.; Wittig, H.

    2014-09-01

    We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle physics community. More specifically, we report on the determination of the light-quark masses, the form factor f+(0), arising in semileptonic K -> pi transition at zero momentum transfer, as well as the decay constant ratio fK/fpi of decay constants and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)LxSU(2)R and SU(3)LxSU(3)R Chiral Perturbation Theory and review the determination of the BK parameter of neutral kaon mixing. The inclusion of heavy-quark quantities significantly expands the FLAG scope with respect to the previous review. Therefore, for this review, we focus on D- and B-meson decay constants, form factors, and mixing parameters, since these are most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. In addition we review the status of lattice determinations of the strong coupling constant alpha_s.

  4. Projectile - Mass asymmetry systematics for low energy incomplete fusion

    NASA Astrophysics Data System (ADS)

    Singh, Pushpendra P.; Yadav, Abhishek; Sharma, Vijay R.; Sharma, Manoj K.; Kumar, Pawan; Sahoo, Rudra N.; Kumar, R.; Singh, R. P.; Muralithar, S.; Singh, B. P.; Bhowmik, R. K.; Prasad, R.

    2015-06-01

    In the present work, low energy incomplete fusion (ICF) in which only a part of projectile fuses with target nucleus has been investigated in terms of various entrance channel parameters. The ICF strength function has been extracted from the analysis of experimental excitation functions (EFs) measured for different projectile-target combinations from near- to well above- barrier energies in 12C,16O(from 1.02Vb to 1.64Vb)+169Tm systems. Experimental EFs have been analysed in the framework statistical model code PACE4 based on the idea of equilibrated compound nucleus decay. It has been found that the value of ICF fraction (FICF) increases with incident projectile energy. A substantial fraction of ICF (FICF ≈ 7 %) has been accounted even at energy as low as ≈ 7.5% above the barrier (at relative velocity νrel ≈0.027) in 12C+169Tm system, and FICF ≈ 10 % at νrel ≈0.014 in 16O+169Tm system. The probability of ICF is discussed in light of the Morgenstern's mass-asymmetry systematics. The value of FICF for 16O+169Tm systems is found to be 18.3 % higher than that observed for 12C+169Tm systems. Present results together with the re-analysis of existing data for nearby systems conclusively demonstrate strong competition of ICF with CF even at slightly above barrier energies, and strong projectile dependence that seems to supplement the Morgenstern's systematics.

  5. MOS Circuitry Would Detect Low-Energy Charged Particles

    NASA Technical Reports Server (NTRS)

    Sinha, Mahadeva; Wadsworth, Mark

    2003-01-01

    Metal oxide semiconductor (MOS) circuits for measuring spatially varying intensities of beams of low-energy charged particles have been developed. These circuits are intended especially for use in measuring fluxes of ions with spatial resolution along the focal planes of mass spectrometers. Unlike prior mass spectrometer focal-plane detectors, these MOS circuits would not be based on ion-induced generation of electrons, and photons; instead, they would be based on direct detection of the electric charges of the ions. Hence, there would be no need for microchannel plates (for ion-to-electron conversion), phosphors (for electron-to-photon conversion), and photodetectors (for final detection) -- components that degrade spatial resolution and contribute to complexity and size. The developmental circuits are based on linear arrays of charge-coupled devices (CCDs) with associated readout circuitry (see figure). They resemble linear CCD photodetector arrays, except that instead of a photodetector, each pixel contains a capacitive charge sensor. The capacitor in each sensor comprises two electrodes (typically made of aluminum) separated by a layer of insulating material. The exposed electrode captures ions and accumulates their electric charges during signal-integration periods.

  6. Selection rules in low energy string effective lagrangians

    NASA Astrophysics Data System (ADS)

    Dolan, L.; Lau, S.

    1992-01-01

    Selection rules which restrict elementary particle interactions are derived as the low-energy limit of superstring theory. A general mechanism is demonstrated, in four-dimensional string tree-amplitudes, whereby the supersymmetric trilinear Yukawa-like couplings in the effective lagrangian which violate lepton number vanish, terms which otherwise occur naturally in supersymmetric versions of the standard model. Explicit expressions for the vertex operators, and all cubic bosonic couplings involving the Yang-Mills gauge bosons and the graviton, together with the scalar and anti-symmetric tensor components of gravity are given. There are no √2 α' corrections to the three-point string tree-amplitudes, a result which eliminates any higher derivative trilinear couplings among these fields in the effective action. In this four-dimensional string theory, expressions are derived for the gravitational coupling constant κ and the Yang-Mills coupling constant gYM in terms of the two string parameters: the universal Regge slope parameter which is the origin of the length scale √2 α', and the dimensionless string coupling constant g. We find κ = {1}/{2}g√2α' and g YM = g .

  7. Low energy electrons and swift ion track structure in PADC

    SciTech Connect

    Fromm, Michel; Quinto, Michele A.; Weck, Philippe F.; Champion, Christophe

    2015-05-27

    The current work aims at providing an accurate description of the ion track-structure in poly-allyl dyglycol carbonate (PADC) by using an up-to-date Monte-Carlo code-called TILDA-V (a French acronym for Transport d’Ions Lourds Dans l’Aqua & Vivo). In this simulation the ion track-structure in PADC is mainly described in terms of ejected electrons with a particular attention done to the Low Energy Electrons (LEEs). After a brief reminder of the most important channels through which LEEs are prone to break a chemical bond, we will report on the simulated energetic distributions of LEEs along an ion track in PADC for particular incident energies located on both sides of the Bragg-peak position. Lastly, based on the rare data dealing with LEEs interaction with polymers or organic molecules, we will emphasise the role played by the LEEs in the formation of a latent track in PADC, and more particularly the one played by the sub-ionization electrons.

  8. Mutual neutralization in low-energy H+ +F- collisions

    NASA Astrophysics Data System (ADS)

    Mezei, J. Zs.; Roos, J. B.; Shilyaeva, K.; Elander, N.; Larson, Å.

    2011-07-01

    The cross section for mutual neutralization in collisions between H+ and F- ions at low energies (E⩽10 eV) is calculated using a molecular close-coupling approach. Two different representations of the quasidiabatic potentials and couplings of HF are used. The effect of autoionization on the cross section is investigated. The coupled Schrödinger equation for the nuclear motion is solved using a numerical integration of the corresponding matrix Riccati equation and the cross section for mutual neutralization is computed from the asymptotic value of the logarithmic derivative of the radial wave function. The magnitude of the cross section for mutual neutralization in this reaction is small compared to other systems. This can be understood by the lack of avoided crossings at large internuclear distances. Resonant structures are found in the cross section and these are assigned with dominant angular momentum quantum number. The cross section for mutual neutralization in collisions of D+ and F- ions is also calculated.

  9. Performance of the Versatile Array of Neutron Detectors at Low Energy (VANDLE)

    NASA Astrophysics Data System (ADS)

    Peters, W. A.; Ilyushkin, S.; Madurga, M.; Matei, C.; Paulauskas, S. V.; Grzywacz, R. K.; Bardayan, D. W.; Brune, C. R.; Allen, J.; Allen, J. M.; Bergstrom, Z.; Blackmon, J.; Brewer, N. T.; Cizewski, J. A.; Copp, P.; Howard, M. E.; Ikeyama, R.; Kozub, R. L.; Manning, B.; Massey, T. N.; Matos, M.; Merino, E.; O'Malley, P. D.; Raiola, F.; Reingold, C. S.; Sarazin, F.; Spassova, I.; Taylor, S.; Walter, D.

    2016-11-01

    The Versatile Array of Neutron Detectors at Low Energy (VANDLE) is a new, highly efficient plastic-scintillator array constructed for decay and transfer reaction experimental setups that require neutron detection. The versatile and modular design allows for customizable experimental setups including beta-delayed neutron spectroscopy and (d,n) transfer reactions in normal and inverse kinematics. The neutron energy and prompt-photon discrimination is determined through the time of flight technique. Fully digital data acquisition electronics and integrated triggering logic enables some VANDLE modules to achieve an intrinsic efficiency over 70% for 300-keV neutrons, measured through two different methods. A custom GEANT4 simulation models aspects of the detector array and the experimental setups to determine efficiency and detector response. A low detection threshold, due to the trigger logic and digitizing data acquisition, allowed us to measure the light-yield response curve from elastically scattered carbon nuclei inside the scintillating plastic from incident neutrons with kinetic energies below 2 MeV.

  10. ON THE CORRELATION OF LOW-ENERGY SPECTRAL INDICES AND REDSHIFTS OF GAMMA-RAY BURSTS

    SciTech Connect

    Geng, J. J.; Huang, Y. F.

    2013-02-10

    It was found by Amati et al. in 2002 that for a small sample of nine gamma-ray bursts (GRBs), more distant events appear to be systematically harder in the soft gamma-ray band. Here, we have collected a larger sample of 65 GRBs, whose time-integrated spectra are well established and can be well fitted with the so-called Band function. It is confirmed that a correlation between the redshifts (z) and the low-energy indices ({alpha}) of the Band function does exist, though it is a bit more scattered than the result of Amati et al. This correlation cannot be simply attributed to the effect of photon reddening. Furthermore, correlations between {alpha} and E {sub peak} (the peak energy in the {nu}F {sub {nu}} spectrum in the rest frame), {alpha} and E {sub iso} (the isotropic energy release), and {alpha} and L {sub iso} (the isotropic luminosity) are also found, which indicate that these parameters are somehow connected. The results may provide useful constraints on the physics of GRBs.

  11. Low-energy electron diffraction investigation of epitaxial growth: Pt and Pd on Pd(100)

    SciTech Connect

    Flynn-Sanders, D.

    1990-09-21

    We investigate the epitaxial growth of Pt and Pd and Pd(100) via spot profile analysis using conventional low-energy electron diffraction (LEED). We resolve a central-spike and diffuse component in the spot profiles, reflecting the layer-occupations and pair-correlations, respectively. Kinetic limitations inhibit layer-by-layer growth at low temperatures. Our data suggest diffusion switches on at ca. 150 K for Pt and ca. 170 K for Pd indicating activation barriers to surface diffusion of ca. 10 and ca. 13 kcal/mol, respectively. To clarify the role of diffusion in determining the resulting film morphology, we develop a growth model that incorporates the adsorption-site requirement and predicts intensity oscillations. We present a new procedure to experimentally determine out-of-phase scattering conditions. At these energies, ring-structure is evident in the profiles during Pd growth between ca. 200 and 400 K. We report ring intensity oscillations as a function of coverage, which demonstrate the filling of individual layers.

  12. Low-energy spin dynamics of the s = 1/2 kagome system herbertsmithite.

    PubMed

    Nilsen, G J; de Vries, M A; Stewart, J R; Harrison, A; Rønnow, H M

    2013-03-13

    The low-energy (ε = ħω < 1 meV), low-temperature (T = 0.05 K) spin dynamics of the s = 1/2 kagome candidate herbertsmithite are probed in the presence of magnetic fields up to 2.5 T. The zero-field spectra reveal a very weak continuum of scattering at T = 10 K and a broad inelastic peak centred at ε(max) = 0.2 meV at lower temperatures, T < 1 K. The broad peak is found to be strongly damped, with a liquid-like structure factor implying correlations at length scales up to r = 6 Å. The field dependence of the peak appears to follow the Zeeman splitting of s = 1/2 excitations, consistent with the weakly split 'doublets' observed in low-temperature specific heat. A possible explanation of these observations is a short-range correlated state involving defect spins between the kagome planes and moments in the kagome layers.

  13. Low energy (e,2e) measurements of CH4 and neon in the perpendicular plane.

    PubMed

    Nixon, Kate L; Murray, Andrew James; Chaluvadi, Hari; Amami, Sadek; Madison, Don H; Ning, Chuangang

    2012-03-01

    Low energy experimental and theoretical triple differential cross sections for the highest occupied molecular orbital of methane (1t(2)) and for the 2p atomic orbital of neon are presented and compared. These targets are iso-electronic, each containing 10 electrons and the chosen orbital within each target has p-electron character. Observation of the differences and similarities of the cross sections for these two species hence gives insight into the different scattering mechanisms occurring for atomic and molecular targets. The experiments used perpendicular, symmetric kinematics with outgoing electron energies between 1.5 eV and 30 eV for CH(4) and 2.5 eV and 25 eV for neon. The experimental data from these targets are compared with theoretical predictions using a distorted-wave Born approximation. Reasonably good agreement is seen between the experiment and theory for neon while mixed results are observed for CH(4). This is most likely due to approximations of the target orientation made within the model.

  14. Chandra Low Energy Transmission Grating Spectrum of SS Cygni in Outburst

    NASA Astrophysics Data System (ADS)

    Mauche, Christopher W.

    2004-07-01

    We have fitted the Chandra Low Energy Transmission Grating (LETG) spectrum of SS Cygni in outburst with a single-temperature blackbody suffering the photoelectric opacity of a neutral column density and the scattering opacity of an outflowing wind. We find that this simple model is capable of reproducing the essential features of the observed spectrum with the blackbody temperature Tbl~250+/-50 kK, hydrogen column density NH~5.0+2.9-1.5×1019cm-2, fractional emitting area f~5.6+60-4.5×10-3, boundary layer luminosity Lbl~5+18-3×1033ergss-1, wind velocity v~2500kms-1, wind mass-loss rate Mw~1.1×1016gs-1, and arbitrary values of the wind ionization fractions of 20 ions of O, Ne, Mg, Si, S, and Fe. Given that in outburst the accretion disk luminosity Ldisk~1×1035ergss-1, Lbl/Ldisk~0.05+0.18-0.03, which can be explained if the white dwarf (or an equatorial belt thereon) is rotating with an angular velocity Ωwd~0.7+0.1-0.2 Hz, hence Vrotsini~2300kms-1. This paper is dedicated to the memory and accomplishments of my colleague and friend Janet Akyüz Mattei, who died on 2004 March 22 after a long battle with acute myelogenous leukemia. Her passing is a great loss to the astronomical community, both amateur and professional.

  15. Molecular-beam scattering

    SciTech Connect

    Vernon, M.F.

    1983-07-01

    The molecular-beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces. Chapter 1 reports results of a low-energy (0.2 kcal/mole) elastic-scattering study of the He-Ar pair potential. The purpose of the study was to accurately characterize the shape of the potential in the well region, by scattering slow He atoms produced by expanding a mixture of He in N/sub 2/ from a cooled nozzle. Chapter 2 contains measurements of the vibrational predissociation spectra and product translational energy for clusters of water, benzene, and ammonia. The experiments show that most of the product energy remains in the internal molecular motions. Chapter 3 presents measurements of the reaction Na + HCl ..-->.. NaCl + H at collision energies of 5.38 and 19.4 kcal/mole. This is the first study to resolve both scattering angle and velocity for the reaction of a short lived (16 nsec) electronic excited state. Descriptions are given of computer programs written to analyze molecular-beam expansions to extract information characterizing their velocity distributions, and to calculate accurate laboratory elastic-scattering differential cross sections accounting for the finite apparatus resolution. Experimental results which attempted to determine the efficiency of optically pumping the Li(2/sup 2/P/sub 3/2/) and Na(3/sup 2/P/sub 3/2/) excited states are given. A simple three-level model for predicting the steady-state fraction of atoms in the excited state is included.

  16. Molecular-beam scattering

    NASA Astrophysics Data System (ADS)

    Vernon, M. F.

    1983-07-01

    The molecular-beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces. Chapter 1 reports results of a low-energy (0.2 kcal/mole) elastic-scattering study of the He-Ar pair potential. The purpose of the study was to accurately characterize the shape of the potential in the well region, by scattering slow He atoms produced by expanding a mixture of He in N2 from a cooled nozzle. Chapter 2 contains measurements of the vibrational predissociation spectra and product translational energy for clusters of water, benzene, and ammonia. The experiments show that most of the product energy remains in the internal molecular motions. Chapter 3 presents measurements of the reaction Na + HC1 (FEMALE) NAC1 + H at collision energies of 5.38 and 19.4 kcal/mole. This is the first study to resolve both scattering angle and velocity for the reaction of a short lived (16 nsec) electronic excited state. Descriptions are given of computer programs written to analyze molecular-beam expansions to extract information characterizing their velocity distributions, and to calculate accurate laboratory elastic-scattering differential cross sections accounting for the finite apparatus resolution. Experimental results which attempted to determine the efficiency of optically pumping the Li(2(2)P/sub 3/2/) and Na(3(2)P/sub 3/2) excited states are given. A simple three-level model for predicting the steady-state fraction of atoms in the excited state is included.

  17. Low-energy Charged Particle Measurements in the Heliosheath

    NASA Astrophysics Data System (ADS)

    Decker, R. B.

    2011-12-01

    This talk will focus on recent measurements from the LECP instruments on Voyager 1 and Voyager 2. Voyager 1 (118 AU, N34 deg.) crossed the termination shock at 94.0 AU in Dec. 2004 and is roughly 24 AU into the inner heliosheath. Voyager 2 (96 AU, S30 deg) crossed the shock at 83.5 AU in Sep. 2007 and is roughly 13 AU into the heliosheath. Large variations in the intensities, energy spectra, and angular distributions of low-energy heliosheath ions and electrons have occurred during the past year, evidently in response to an increase in the number of solar active regions in January 2010. For example, starting around 2010.8, ion intensities at Voyager 1 began a two-step exponential decrease. The intensities of ions below 0.5 MeV fell by 40%, reaching minima around 2011.5 that were the lowest measured since mid-2005. During the intensity drop at Voyager 1 the ion energy spectrum evolved to a single power-law with an index -1.5. Similar intensity drops began somewhat earlier at Voyager 2, and the intensity minima of the low-energy ions occurred on 2011.2, one-third of a year earlier than at Voyager 1. In addition, after the ion intensities had recovered at Voyager 2, they were deficient at lower energies compared to the pre-drop levels, causing the energy spectrum to flatten with decreasing energy. During the intensity drop at Voyager 2, ion angular distributions evolved from convective-like, consistent with the measured plasma flow velocity, to azimuthal, more consistent with unidirectional streaming along the mean magnetic field. We will also summarize the heliosheath plasma flow velocity in the R-T (instrument scan) plane that is estimated using angular data from the three lowest energy Voyager 1 LECP ion channels, which cover 40-139 keV. The estimated radial component of flow decreased from about 60 km/s to about 0 km/s at a rate of -19 km/s/yr during 2008.7-2010.3, was consistent with 0 km/s from 2010.3-2011.0, and then went negative, averaging about -13 km

  18. Sleep inducing effect of low energy emission therapy.

    PubMed

    Reite, M; Higgs, L; Lebet, J P; Barbault, A; Rossel, C; Kuster, N; Dafni, U; Amato, D; Pasche, B

    1994-01-01

    The sleep inducing effect of a 15 min treatment with either an active or an inactive Low Energy Emission Therapy (LEET) device emitting amplitude-modulated electromagnetic (EM) fields was investigated in a double-blind cross-over study performed on 52 healthy subjects. All subjects were exposed to both active and inactive LEET treatment sessions, with an interval of at least 1 week between the two sessions. LEET consists of 27.12 MHz amplitude-modulated (sine wave) EM fields emitted intrabuccally by means of an electrically conducting mouthpiece in direct contact with the oral mucosa. The estimated local peak SAR is less than 10 W/kg in the oral mucosa and 0.1 to 100 mW/kg in brain tissue. No appreciable sensation is experienced during treatment, and subjects are therefore unable to tell whether they are receiving an active or an inactive treatment. In this study the active treatment consisted of EM fields intermittently amplitude-modulated (sine wave) at 42.7 Hz for 3 s followed by a pause of 1 s during which no EM fields were emitted. During the inactive treatment no EM fields were emitted. Baseline EEGs were obtained and 15 min post-treatment EEGs were recorded and analyzed according to the Loomis classification. A significant decrease (paired t test) in sleep latency to stage B2 (-1.78 +/- 5.57 min, P = 0.013), and an increase in the total duration of stage B2 (1.15 +/- 2.47 min, P = 0.0008) were observed on active treatment as compared with inactive treatment.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8155071

  19. Low-energy electric dipole response of Sn isotopes

    NASA Astrophysics Data System (ADS)

    Papakonstantinou, P.; Hergert, H.; Ponomarev, V. Yu.; Roth, R.

    2014-03-01

    We study the low-energy dipole (LED) strength distribution along the Sn isotopic chain in both the isoscalar (IS) and the isovector (IV, or E1) electric channels, to provide testable predictions and guidance for new experiments with stable targets and radioactive beams. We use the self-consistent quasi-particle random-phase approximation (QRPA) with finite-range interactions and mainly the Gogny D1S force. We analyze also the performance of a realistic two-body interaction supplemented by a phenomenological three-body contact term. We find that from N =50 and up to the N =82 shell closure (132Sn) the lowest-energy part of the IS-LED spectrum is dominated by a collective transition whose properties vary smoothly with neutron number and which cannot be interpreted as a neutron-skin oscillation. For the neutron-rich species this state contributes to the E1 strength below particle threshold, but much more E1 strength is carried by other, weak but numerous transitions around or above threshold. We find that strong structural changes in the spectrum take effect beyond N =82, namely increased LED strength and lower excitation energies. Our results with the Gogny interaction are compatible with existing data. On this basis we predict that (a) the summed IS strength below particle threshold shall be of the same order of magnitude for N =50-82, (b) the summed E1 strength up to approximately 12 MeV shall be similar for N =50-82 MeV, while (c) the summed E1 strength below threshold shall be of the same order of magnitude for N ≈64-82 and much weaker for the lighter, more-symmetric isotopes. We point out a general agreement of our results with other nonrelativistic studies, the absence of a collective IS mode in some of those studies, and a possibly radical disagreement with relativistic models.

  20. Screening in Low Energy Nuclear Reactions of Importance to Astrophysics

    NASA Astrophysics Data System (ADS)

    Miley, George H.; Hora, Heinz; Luo, Nie

    2004-05-01

    Recent experiments in the LUNAR (Laboratory for Underground Nuclear Astrophysics) project have shown anonymously high electron screening may occur during acceleration driven low energy (<400 kV) ion bombardment of solid targets [1]. These effects become particularly important for E/ Ue < 100 (here E= ion energy and Ue = electron-screening potential energy). Thus these effects become significant for the understanding of reactions involved in nucleosynthesis of the elements and the interpretation of astrophysical data [1]. Another example of the behavior is the surprising threshold behavior near 18 keV for deuterons stopping in 3He gas at energies below the Bragg peak [2]. As pointed out in ref [1], the theoretical explanation for these effects is still under debate. Several researchers have proposed variations of the Trojan Horse Method (THM) to explain these effects [3]. In this paper, we propose an alternate mechanism associated with electron charge accumulation around the target atoms arising from the solid-state structure of the host. This concept will be explained in terms of density functional calculations of charge density profiles in a target undergoing ion dynamic effects [4]. REFERENCES [1] F. Strieder, et al., Naturwissenschaften (2000)88:461-467 [2] A. Formicola, et al., (2000) Eur Phys J. A 8:443-446 [3] S. Typel and H H Wolter, (2000) Few-Body System 29:75-93 [4] G. Miley and H. Hora, (2000) Nuclear Reactions in Solids, APS mtg. Lansing, MI [5] G. Miley, A. Lipson, N. Luo, and H. Hora, (2003) IEEE NSS/MIC Conf., Portland, OR

  1. Low-energy deuteron-induced reactions on 93Nb

    NASA Astrophysics Data System (ADS)

    Avrigeanu, M.; Avrigeanu, V.; Bém, P.; Fischer, U.; Honusek, M.; Koning, A. J.; Mrázek, J.; Šimečková, E.; Štefánik, M.; Závorka, L.

    2013-07-01

    The activation cross sections of (d,p), (d,2n), (d,2np+nd+t), (d,2nα), and (d,pα) reactions on 93Nb were measured in the energy range from 1 to 20 MeV using the stacked-foil technique. Then, within a simultaneous analysis of elastic scattering and reaction data, the available elastic-scattering data analysis was carried out in order to obtain the optical potential for reaction cross-section calculations. Particular attention was paid to the description of the breakup mechanism and direct reaction stripping and pick-up, followed by pre-equilibrium and compound-nucleus calculations. The measured cross sections as well as all available deuteron activation data of 93Nb were compared with results of local model calculations carried out using the codes fresco and stapre-h and both default and particular predictions of the code talys-1.4 and tendl-2012-evaluated data.

  2. Low energy electron elastic reflection from solid surfaces

    NASA Astrophysics Data System (ADS)

    Starý, Vladimír.; Zemek, Josef

    2004-09-01

    Using our Monte-Carlo (MC) code, we calculated the ratio of the coefficients of elastic reflection of electrons from Si, SiO 2 and Au to those of Cu and Al in the electron energy range 0.2-1.0 and 1.5 keV (Au-Cu), respectively. The electron scattering was simulated by a single scattering model. For the MC calculations, we compared the elastic differential cross-sections calculated using a static field approximation with relativistic partial wave analysis on either the Thomas-Fermi-Dirac potential of free atoms (TFD model) or the Hartree-Fock-Wigner-Seitz (muffin-tin) potential of atoms in the solid state (HFWS model). The MC data were compared with the experimental values. For both models, reasonably good agreement for Si-Cu and SiO 2-Cu systems was found. In the Au-Cu system, better agreement was achieved using the TFD model. The addition of C in a surface interaction layer of 2-5 nm improves the agreement between simulated and experimental values for the Si-Al and Si-SiO 2 systems.

  3. Model independence of scattering of three identical bosons in two dimensions

    SciTech Connect

    Adhikari, S.K. ); Delfino, A. Departamento de Fisica, Universidade Federal Fluminense, Niteroi, Rio de Janeiro ); Frederico, T. ); Tomio, L. )

    1993-02-01

    Within the framework of scattering integral equations in momentum space, we present numerical results of scattering of three identical bosons at low energies in two dimensions for short-range separable potentials. An analysis of the present numerical results reveals the three-particle scattering observables to be independent of potential shape provided the low-energy two-particle binding energy and scattering length are held fixed throughout the investigation. We think that the present conclusion of model independence will be valid for any potential, local or nonlocal, whose range is much smaller than the size of the two-particle bound state.

  4. Beam dynamics in an ultra-low energy storage rings (review of existing facilities and feasibility studies for future experiments)

    NASA Astrophysics Data System (ADS)

    Papash, A. I.; Smirnov, A. V.; Welsch, C. P.

    2014-03-01

    Storage rings operating at ultra-low energies and in particular electrostatic storage rings have proven to be invaluable tools for atomic and molecular physics. Due to the mass independence of the electrostatic rigidity, these machines are able to store a wide range of different particles, from light ions to heavy singly charged bio-molecules. However, earlier measurements showed strong limitations on beam intensity, fast decay of ion current, reduced life time etc. The nature of these effects was not fully understood. Also a large variety of experiments in future generation ultra-low energy storage and decelerator facilities including in-ring collision studies with a reaction microscope require a comprehensive investigation of the physical processes involved into the operation of such rings. In this paper, we present review of non-linear and long term beam dynamics studies on example of the ELISA, AD Recycler, TSR and USR rings using the computer codes BETACOOL, OPERA-3D and MAD-X. The results from simulations were benchmarked against experimental data of beam losses in the ELISA storage ring. We showed that decay of beam intensity in ultra-low energy rings is mainly caused by ion losses on ring aperture due to multiple scattering on residual gas. Beam is lost on ring aperture due to small ring acceptance. Rate of beam losses increases at high intensities because of the intra-beam scattering effect adds to vacuum losses. Detailed investigations into the ion kinetics under consideration of the effects from electron cooling and multiple scattering of the beam on a supersonic gas jet target have been carried out as well. The life time, equilibrium momentum spread and equilibrium lateral spread during collisions with this internal gas jet target were estimated. In addition, the results from experiments at the TSR ring, where low intensity beam of CF+ ions at 93 keV/u has been shrunk to extremely small dimensions have been reproduced. Based on these simulations

  5. THERMAL: A routine designed to calculate neutron thermal scattering

    SciTech Connect

    Cullen, D.E.

    1995-02-24

    THERMAL is designed to calculate neutron thermal scattering that is isotropic in the center of mass system. At low energy thermal motion will be included. At high energies the target nuclei are assumed to be stationary. The point of transition between low and high energies has been defined to insure a smooth transition. It is assumed that at low energy the elastic cross section is constant in the center of mass system. At high energy the cross section can be of any form. You can use this routine for all energies where the elastic scattering is isotropic in the center of mass system. In most materials this will be a fairly high energy.

  6. Monthly Variations of Low-Energy Ballistic Transfers to Lunar Halo Orbits

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.

    2010-01-01

    The characteristics of low-energy transfers between the Earth and Moon vary from one month to the next largely due to the Earth's and Moon's non-circular, non-coplanar orbits in the solar system. This paper characterizes those monthly variations as it explores the trade space of low-energy lunar transfers across many months. Mission designers may use knowledge of these variations to swiftly design desirable low-energy lunar transfers in any given month.

  7. The Marshall Space Flight Center Low-Energy Ion Facility: A preliminary report

    NASA Technical Reports Server (NTRS)

    Biddle, A. P.; Reynolds, J. W.; Chisholm, W. L., Jr.; Hunt, R. D.

    1983-01-01

    The Low-Energy Ion Facility (LEIF) is designed for laboratory research of low-energy ion beams similar to those present in the magnetosphere. In addition, it provides the ability to develop and calibrate low-energy, less than 50 eV, plasma instrumentation over its full range of energy, mass, flux, and arrival angle. The current status of this evolving resource is described. It also provides necessary information to allow users to utilize it most efficiently.

  8. Low-energy Coulomb excitation of radioactive ^70Se

    NASA Astrophysics Data System (ADS)

    Hurst, Aaron

    2007-10-01

    An isobarically pure beam of ^70Se ions was post accelerated to an energy of 206 MeV using REX-ISOLDE. Coulomb-excitation yields for states in the beam and target nuclei were deduced by recording de-excitation γ rays in the highly segmented MINIBALL γ-ray spectrometer in coincidence with scattered particles in a silicon detector. At these energies, the Coulomb-excitation yield for the 2^+1 state in ^70Se is expected to be strongly sensitive to the sign of the spectroscopic quadrupole moment through the nuclear reorientation effect. Experimental evidence is presented here for a prolate shape for this state, using an earlier published lifetime measurement, reopening the question over whether there are deformed oblate shapes close to the ground state in the neutron-deficient selenium isotopes.

  9. Low-energy vibrational dynamics of cesium borate glasses.

    PubMed

    Crupi, C; D'Angelo, G; Vasi, C

    2012-06-01

    Low-temperature specific heat and inelastic light scattering experiments have been performed on a series of cesium borate glasses and on a cesium borate crystal. Raman measurements on the crystalline sample have revealed the existence of cesium rattling modes in the same frequency region where glasses exhibit the boson peak (BP). These localized modes are supposed to overlap with the BP in cesium borate glasses affecting its magnitude. Their influence on the low frequency vibrational dynamics in glassy samples has been considered, and their contribution to the specific heat has been estimated. Evidence for a relation between the changes of the BP induced by the increased amount of metallic oxide and the variations of the elastic medium has been provided.

  10. Low Energy Electrons as Probing Tool for Astrochemical Reaction Mechanisms

    NASA Astrophysics Data System (ADS)

    Hendrik Bredehöft, Jan; Swiderek, Petra; Hamann, Thorben

    hitting anything solid, they will create secondary electrons. These electrons are in fact the energy source needed to run interstellar chemistry. Slow electrons can in principle trigger three different primary processes in a molecule. The first is ionisation by electron impact (EI), which is used to create ions in mass spectrometry. In this process an electron hits a molecule M and knocks an outer shell electron to create a cation. This occurs whenever the electron energy is above the ionisation threshold of the target molecule. Another possibility is the attachment of a slow electron to a molecule to create an anion. This can occur at sharply defined resonance energies specific to the molecule M. A third possibility is to excite the molecule M to a neutral state M∗ .[9] M + e- -> M+ + 2 e- (Electron impact ionisation) M + e- -> M- (Electron attachment) M + e- -> M∗ + e- (Neutral excitation) The created states M+ , M- and M∗ are usually not stable states so they very often dissociate into ions and radicals, which can then further react with neighbouring molecules to form new chemical species. In these chemical reactions some products can be formed even at very low temperatures that would otherwise require a lot of thermal energy and/or special catalysts. The formation of ethylamine from ethylene and ammonia by hydroamination is one such example. The reaction is characterized by a high activation barrier caused by the electronic repulsion between the electron density rich C=C double bound and the lone pair electrons of ammo-nia. The reaction also has a highly negative entropy, so it becomes less favourable at higher temperatures, ruling out heat as a means to facilitate the reaction. In classical chemistry this problem is overcome by the use of catalysts. Unfortunately there still is no general catalyst for this kind of reaction. Recently it was shown that the reaction can efficiently be induced by low energy electron radiation.[10] One of the reaction partners is

  11. Smartphone-Based Indoor Localization with Bluetooth Low Energy Beacons.

    PubMed

    Zhuang, Yuan; Yang, Jun; Li, You; Qi, Longning; El-Sheimy, Naser

    2016-01-01

    Indoor wireless localization using Bluetooth Low Energy (BLE) beacons has attracted considerable attention after the release of the BLE protocol. In this paper, we propose an algorithm that uses the combination of channel-separate polynomial regression model (PRM), channel-separate fingerprinting (FP), outlier detection and extended Kalman filtering (EKF) for smartphone-based indoor localization with BLE beacons. The proposed algorithm uses FP and PRM to estimate the target's location and the distances between the target and BLE beacons respectively. We compare the performance of distance estimation that uses separate PRM for three advertisement channels (i.e., the separate strategy) with that use an aggregate PRM generated through the combination of information from all channels (i.e., the aggregate strategy). The performance of FP-based location estimation results of the separate strategy and the aggregate strategy are also compared. It was found that the separate strategy can provide higher accuracy; thus, it is preferred to adopt PRM and FP for each BLE advertisement channel separately. Furthermore, to enhance the robustness of the algorithm, a two-level outlier detection mechanism is designed. Distance and location estimates obtained from PRM and FP are passed to the first outlier detection to generate improved distance estimates for the EKF. After the EKF process, the second outlier detection algorithm based on statistical testing is further performed to remove the outliers. The proposed algorithm was evaluated by various field experiments. Results show that the proposed algorithm achieved the accuracy of <2.56 m at 90% of the time with dense deployment of BLE beacons (1 beacon per 9 m), which performs 35.82% better than <3.99 m from the Propagation Model (PM) + EKF algorithm and 15.77% more accurate than <3.04 m from the FP + EKF algorithm. With sparse deployment (1 beacon per 18 m), the proposed algorithm achieves the accuracies of <3.88 m at 90% of the

  12. Smartphone-Based Indoor Localization with Bluetooth Low Energy Beacons.

    PubMed

    Zhuang, Yuan; Yang, Jun; Li, You; Qi, Longning; El-Sheimy, Naser

    2016-04-26

    Indoor wireless localization using Bluetooth Low Energy (BLE) beacons has attracted considerable attention after the release of the BLE protocol. In this paper, we propose an algorithm that uses the combination of channel-separate polynomial regression model (PRM), channel-separate fingerprinting (FP), outlier detection and extended Kalman filtering (EKF) for smartphone-based indoor localization with BLE beacons. The proposed algorithm uses FP and PRM to estimate the target's location and the distances between the target and BLE beacons respectively. We compare the performance of distance estimation that uses separate PRM for three advertisement channels (i.e., the separate strategy) with that use an aggregate PRM generated through the combination of information from all channels (i.e., the aggregate strategy). The performance of FP-based location estimation results of the separate strategy and the aggregate strategy are also compared. It was found that the separate strategy can provide higher accuracy; thus, it is preferred to adopt PRM and FP for each BLE advertisement channel separately. Furthermore, to enhance the robustness of the algorithm, a two-level outlier detection mechanism is designed. Distance and location estimates obtained from PRM and FP are passed to the first outlier detection to generate improved distance estimates for the EKF. After the EKF process, the second outlier detection algorithm based on statistical testing is further performed to remove the outliers. The proposed algorithm was evaluated by various field experiments. Results show that the proposed algorithm achieved the accuracy of <2.56 m at 90% of the time with dense deployment of BLE beacons (1 beacon per 9 m), which performs 35.82% better than <3.99 m from the Propagation Model (PM) + EKF algorithm and 15.77% more accurate than <3.04 m from the FP + EKF algorithm. With sparse deployment (1 beacon per 18 m), the proposed algorithm achieves the accuracies of <3.88 m at 90% of the

  13. Smartphone-Based Indoor Localization with Bluetooth Low Energy Beacons

    PubMed Central

    Zhuang, Yuan; Yang, Jun; Li, You; Qi, Longning; El-Sheimy, Naser

    2016-01-01

    Indoor wireless localization using Bluetooth Low Energy (BLE) beacons has attracted considerable attention after the release of the BLE protocol. In this paper, we propose an algorithm that uses the combination of channel-separate polynomial regression model (PRM), channel-separate fingerprinting (FP), outlier detection and extended Kalman filtering (EKF) for smartphone-based indoor localization with BLE beacons. The proposed algorithm uses FP and PRM to estimate the target’s location and the distances between the target and BLE beacons respectively. We compare the performance of distance estimation that uses separate PRM for three advertisement channels (i.e., the separate strategy) with that use an aggregate PRM generated through the combination of information from all channels (i.e., the aggregate strategy). The performance of FP-based location estimation results of the separate strategy and the aggregate strategy are also compared. It was found that the separate strategy can provide higher accuracy; thus, it is preferred to adopt PRM and FP for each BLE advertisement channel separately. Furthermore, to enhance the robustness of the algorithm, a two-level outlier detection mechanism is designed. Distance and location estimates obtained from PRM and FP are passed to the first outlier detection to generate improved distance estimates for the EKF. After the EKF process, the second outlier detection algorithm based on statistical testing is further performed to remove the outliers. The proposed algorithm was evaluated by various field experiments. Results show that the proposed algorithm achieved the accuracy of <2.56 m at 90% of the time with dense deployment of BLE beacons (1 beacon per 9 m), which performs 35.82% better than <3.99 m from the Propagation Model (PM) + EKF algorithm and 15.77% more accurate than <3.04 m from the FP + EKF algorithm. With sparse deployment (1 beacon per 18 m), the proposed algorithm achieves the accuracies of <3.88 m at 90% of the

  14. Meta-analysis on intravascular low energy laser therapy

    NASA Astrophysics Data System (ADS)

    Zhao, Shu-Dong; Liu, Timon Cheng-Yi; Wang, Yan-Fang; Liu, Song-Hao

    2008-12-01

    Intravascular low energy laser therapy (ILELT) was put forward for cardiocirculatory diseases in USA in 1982, was popular in Russia in 1980s, and then in China in 1990s. The therapeutic effects of ILELT and drugs in comparison with drugs only on Chinese patients and their blood parameters were analyzed with meta-analyses and reported as (OR, 95%CI) for patient improvement and (WMD, 95% CI) for blood parameter improvement, where 95%CI, OR and WMD denoted 95% confidence intervals, odds ratio and weighted mean difference, respectively. It was found that the patients of cerebral infarction (2.39, 2.09~2.74) and cerebrovascular diseases (2.97, 1.69~2.53) were cured, respectively, (P < 0.01), and the symptom improvement of patients of cerebral infarction, cerebrovascular diseases and diabetes were significant (3.13, 2.79~3.51), (4.92, 3.39~7.14) , and (3.80, 2.79~5.18), and mild (3.66, 3.15~4.24), (4.95, 2.77~8.84), and (7.11, 4.54~11.13), respectively, (P < 0.01). It was also found that the blood parameters such as cholesterol (-0.78, -1.32~-0.24), total cholesterol (-1.08, -1.80~-0.36), low density lipoprotein cholesterol (-0.6, -1.01~-0.19), triacylglycerol (0.63, -0.83~-0.42), high density lipoprotein (0.34, 0.10~0.59), erythrocyte aggregation index (-0.24, -0.27~-0.21), erythrocyte Sedimentation Rate (-4.57, -7.26~-1.89), fibrinogen (-0.76, -1.31~-0.21), whole blood contrast viscosity (-0.40, -0.69~-0.12), low cut blood viscosity (-1.2, -1.93~-0.48), high cut blood viscosity (-0.62, -0.92~-0.32), whole blood viscosity(-1.2, -1.85~-0.54) and plasma blood contrast viscosity(-0.07, -0.12~-0.03) were found improved (P < 0.05). It is concluded that the patients of cerebral infarction, cerebrovascular diseases and diabetes might be improved with ILELT, which might be mediated by blood parameter improvement.

  15. Random-matrix approach to the statistical compound nuclear reaction at low energies using the Monte-Carlo technique

    SciTech Connect

    Kawano, Toshihiko

    2015-11-10

    This theoretical treatment of low-energy compound nucleus reactions begins with the Bohr hypothesis, with corrections, and various statistical theories. The author investigates the statistical properties of the scattering matrix containing a Gaussian Orthogonal Ensemble (GOE) Hamiltonian in the propagator. The following conclusions are reached: For all parameter values studied, the numerical average of MC-generated cross sections coincides with the result of the Verbaarschot, Weidenmueller, Zirnbauer triple-integral formula. Energy average and ensemble average agree reasonably well when the width I is one or two orders of magnitude larger than the average resonance spacing d. In the strong-absorption limit, the channel degree-of-freedom ν a is 2. The direct reaction increases the inelastic cross sections while the elastic cross section is reduced.

  16. Investigation of the mechanism of impurity assisted nanoripple formation on Si induced by low energy ion beam erosion

    SciTech Connect

    Koyiloth Vayalil, Sarathlal; Gupta, Ajay; Roth, Stephan V.; Ganesan, V.

    2015-01-14

    A detailed mechanism of the nanoripple pattern formation on Si substrates generated by the simultaneous incorporation of pure Fe impurities at low energy (1 keV) ion beam erosion has been studied. To understand and clarify the mechanism of the pattern formation, a comparative analysis of the samples prepared for various ion fluence values using two complimentary methods for nanostructure analysis, atomic force microscopy, and grazing incidence small angle x-ray scattering has been done. We observed that phase separation of the metal silicide formed during the erosion does not precede the ripple formation. It rather concurrently develops along with the ripple structure. Our work is able to differentiate among various models existing in the literature and provides an insight into the mechanism of pattern formation under ion beam erosion with impurity incorporation.

  17. Time-of-flight analyzer system to detect reflected particles from a solid surface following low-energy particle injection

    SciTech Connect

    Yamaoka, H.; Tanaka, N.; Tsumori, K.; Nishiura, M.; Kenmotsu, T.; Hirouchi, T.; Kisaki, M.; Shinto, K.; Sasao, M.; Matsumoto, Y.; Wada, M.

    2008-02-15

    We have developed a time-of-flight analyzer to measure energy distributions of reflected particles from solid surfaces bombarded by low-energy (1-2 keV) ions. The analyzer yields energy distributions of neutrals which can be compared with the energy distributions of charged particles measured by a magnetic deflection-type momentum analyzer. We have tested the system to measure the angular dependence of energy and intensity for neutrals reflected from a polycrystalline W target. The energies of the reflected neutrals are much smaller than the incident ion energies, suggesting multiple scattering in the target. No angular dependence is observed under the condition that the sum of the incident and reflected angles is constant. The intensity of the reflected neutrals takes the maximum around the mirror angle. We compare these characteristics of neutral particle reflections with those of reflected ions.

  18. Long-time stability of a low-energy electron diffraction spin polarization analyzer for magnetic imaging.

    PubMed

    Lofink, F; Hankemeier, S; Frömter, R; Kirschner, J; Oepen, H P

    2012-02-01

    The time stability of a polarization analyzer that is used for imaging of magnetic structures in a scanning electron microscope with spin polarization analysis (spin-SEM or SEMPA) is investigated. The detector is based on the diffraction of low-energy electrons at a W(100) crystal at 104.5 eV (LEED detector). Due to the adsorption of hydrogen from residual gas, a change of the scattering conditions is found that causes an angular shift of the LEED beams as well as changes of intensity. The quality factor, which describes the efficiency of the detector in SEMPA application, however, is found to be almost constant up to a hydrogen coverage of θ ≈ 0.25. This gives stable working conditions within roughly 1 h at vacuum conditions of 10(-10) mbar.

  19. Interatomic Coulombic decay as a new source of low energy electrons in slow ion-dimer collisions.

    PubMed

    Iskandar, W; Matsumoto, J; Leredde, A; Fléchard, X; Gervais, B; Guillous, S; Hennecart, D; Méry, A; Rangama, J; Zhou, C L; Shiromaru, H; Cassimi, A

    2015-01-23

    We provide the experimental evidence that the single electron capture process in slow collisions between O^{3+} ions and neon dimer targets leads to an unexpected production of low-energy electrons. This production results from the interatomic Coulombic decay process, subsequent to inner-shell single electron capture from one site of the neon dimer. Although pure one-electron capture from the inner shell is expected to be negligible in the low collision energy regime investigated here, the electron production due to this process overtakes by 1 order of magnitude the emission of Auger electrons by the scattered projectiles after double-electron capture. This feature is specific to low charge states of the projectile: similar studies with Xe^{20+} and Ar^{9+} projectiles show no evidence of inner-shell single-electron capture. The dependence of the process on the projectile charge state is interpreted using simple calculations based on the classical over the barrier model. PMID:25658997

  20. Incoherent scatterer in a Luttinger liquid: a new paradigmatic limit.

    PubMed

    Altland, Alexander; Gefen, Yuval; Rosenow, Bernd

    2012-03-30

    We address the problem of a Luttinger liquid with a scatterer that allows for both coherent and incoherent scattering channels. The asymptotic behavior at zero temperature is governed by a new stable fixed point: A Goldstone mode dominates the low energy dynamics, leading to universal behavior. This limit is marked by equal probabilities for forward and backward scattering. Notwithstanding this nontrivial scattering pattern, we find that the shot noise as well as cross-current correlations vanish. We thus present a paradigmatic picture of an impurity in the Luttinger model, alternative to the Kane-Fisher picture.